“There was a footpath leading across the fields to New Southgate, and I used to go there alone to watch the sunset and contemplate suicide. I did not, however, commit suicide, because I wished to know more about mathematics.”
-Bertrand Russell, Nobel Laureate and Mathematician

It is mystical when you step outside on a snowy morning. Snowflakes are swirling around the vast sky and falling and blanketing the ground. If a snowflake lands on you, it is like a winter angel. There are no flowers around, for they cannot survive the cold; yet what lies before your eyes is an incredible beauty. And it’s remarkable, you come to realize, that no two snowflakes are alike. It is as if the uniqueness of a snowflake is controlled by a divine force. The individuality of a snowflake’s structure draws a parallel to human life. Like snowflakes, everyone has a unique story to tell.

I am not the only one who ponders about snowflakes; many mathematicians do the same. Actually, they think about the characteristics of snowflakes because they are particularly important for three basic mathematical principles: pattern, symmetry, and symmetry breaking.

A little-known scientist, Wilson Bentley, a.k.a. “the Snowflake Man” took pictures of snowflakes almost every day and observed them until he died. You can buy his book about his work on Amazon. If you wish to know why he did it, read about it at snowflakebentley.com.

“Under the microscope, I found that snowflakes were miracles of nature; and it seemed a shame that this beauty should not be seen and appreciated by others. Every crystal was a masterpiece of design and no one design was ever repeated. When a snowflake melted, that design was forever lost. That beauty was gone, without leaving any record behind.”
-Wilson Bentley

When I checked the Oxford dictionary, there were 3 definitions for the word “pattern.” Two of these definitions [listed below] are important for this article.

Pattern: 1. A repeated decorative design; 2. An example for others to follow.

When we check the pictures and delve deeper into each snowflake, we will see that the structures of the snowflakes are totally different. However, they have something in common: symmetry and a hexagonal structure.

These perfect ice crystals are genuine, even though it is hard to believe they are not fake.

When I take a close look at a snowflake, the beauty of the combination of ice molecules fascinates me every time; each flake is unique. However, uniqueness is not the point here. The things that make snowflakes important objects for mathematicians are their symmetry and their hexagonal structure. Math-loving people have a lot of interest in transformations. They love moving objects. And, surprisingly, if an object is symmetric, transformations are not even noticed by many.

To be more precise, when you have a hexagonal symmetric snowflake, or any other symmetrical object, when you rotate it in any direction, 60°, 120°, 180°, 240°, 300°, or 360°, people watching you wouldn’t realize it. If you check the images below, you will see rotated shapes but no difference. It appears to be the same shape in exactly the same place.

1- Counterclockwise rotation by 120°

2- Reflection through a vertical axis

3- Reflection axes of a snowflake[1]

Snowflakes also possess reflectional symmetry. If we stand in front of a mirror, our reflection looks exactly the same. Hence, if we put a mirror in the middle of a snowflake, there will be a reflection. For a snowflake, we can put a mirror 6 different ways. Thus, we can say that a snowflake has 12 symmetries: 6 from reflections, and 6 from rotations.[2]

Now we can define symmetry as a transformation that leaves things unchanged. We can also claim that a combination of any of the transformations will give us exactly the same shape. For instance, we can rotate our snowflake 60° two or three times in a row and flip it over, and it will remain unchanged.

At this point, you might ask the question: “You have all these fancy symmetries for this particular snowflake. But, does every snowflake possess the same symmetries?”

Snow is a molecular structure of an ice crystal. And ice is a structured substance. It is a different form of water. When the water cools down, the molecules move more slowly, and this begins to impact how the molecules line up. Hydrogen atoms of one water molecule bond with two oxygen atoms. As the water freezes, the molecules arrange into hexagonal patterns. They prefer to stay as far away from each other as possible, and that makes them take up more space. The large space affects density. The density of ice becomes less dense than water. This is why ice floats. Almost all other liquids have a higher density when they freeze.

When we examine an ice crystal carefully under normal conditions, we always see a combination of molecules with six-fold symmetry. Snowflake molecules make a honeycomb structure. This results in an inordinate amount of hexagonal symmetry in these molecular three-dimensional structures.

Okay, we saw the structure of a snowflake under normal conditions. But, what if we changed those conditions? Johannes Kepler answered this question after his experiments and wrote a book about snowflakes, particularly The Six-Cornered Snowflake.

There are two key elements which affect the structure of a snowflake: temperature and moisture. Each time the temperature or the amount of moisture change, the structure of a snowflake changes. If you check the snow crystal morphology diagram below, you will see that when the temperature nears 0° and humidity is high, the structure of a snowflake will be flowery. Flowery structures are called dendrites. When you make it a little bit colder, the structure will be fancy hexagonal plates. We can apply many combinations and get varying structures.

The Snow Crystal Morphology Diagram. Source: Snow Crystals – http://www.snowcrystals.com/science/science.html

Professor of physics Kenneth G. Libbrecht is the owner of the diagram below. In a PBS interview, he said, “It’s a mystery as to why snowflake shapes go from plates to columns to plates to columns as the temperature lowers. That’s one of the things I’ve been trying to understand. It has been a mystery for about 75 years, and it’s still unsolved.”[3]

The Shapes of Snowflakes | Source

In the end, although the structure of (almost) all snowflakes are the same, some of them are not completely hexagonal. For instance, there are some snowflakes that have tree structures. Some snowflakes have branches, and each branch has tiny branches.

But, why is the structure of some snowflakes not hexagonal?

So far, we have talked about pictures which were taken at a particular instant. We have seen the pictures of the motion of the snowflakes for the smallest amount of time that can be measured. However, a snowflake never stops spinning in the air. They tend to oscillate. That means the shape of the snowflake is changing all the time. But how? When you see a snowflake in the air, it changes its place after a second because it would be whirled about, and it will be under different conditions at that time. This process will occur up until the snowflake lands on the ground. We know from the diagram that the temperature and amount of moisture always affect the shape of a snowflake. While small-scale conditions are almost the same, on a larger-time scale, conditions will differ. And these differences will change every corner of a hexagonal snowflake, resulting in a different structure. This is the main reason behind the variety of snowflake structures and uniqueness.

In conclusion, we can say that a snowflake can preserve its six-fold symmetry at all times. I think we have another reason to love mathematics! I want to finish my piece with Hermann Hankel’s words:

“In most sciences one generation tears down what another has built, and what one has established another undoes. In mathematics alone, each generation adds a new story to the old structure.”

Thermostats are devices that keep temperature at the desired level. They are used in refrigerators, dishwashers, electric ovens, water heaters, washing machines, and central heating. Without a properly functioning thermostat, the devices or machines are likely to break down.

Did you know that there is also a thermostat in our body that comes with a lifelong guarantee? How about the fact that each is customized for each body? The thermostat in our body is so durable and dependable that it continues to regulate our body temperature for a life time, through illness and health, and good and bad weather.

Hypothermia and hyperthermia

When you are alive and kicking, your thermostat works within a temperature range of one degree (36.5 °C–37.5 °C). If your body temperature taken in your mouth is above or below this range, it means that your body is signaling certain problems. Temperatures below 35°C lead to hypothermia, while those above 39°C cause an opposite problem called hyperthermia.

Hypothermia is a drop in body temperature, generally due to such factors as rain, wind, snow, or cold water. Prolonged hypothermia first causes shivering and blackout, then death. People who fall into water in shipwrecks die more of hypothermia than of drowning.

Hyperthermia, on the other hand, is a condition in which the body temperature rises to high levels because of factors such as inflammatory diseases and prolonged exposure to sunlight. If it continues for long, hyperthermia causes fatigue, dizziness, nausea and problems in blood pressure. It may lead to seizures or death, especially in children, unless immediate aid is provided.

Where is our thermostat?

Whether you inhabit Siberian taigas or African deserts, your body temperature is kept within the normal range. Our thermostat, called the thermoregulation center, takes up a small place in the hypothalamus of our brain. Assigned the task of balancing our body temperature, the center activates the system to decrease the temperature when it rises and to increase it when it drops. The center is composed of two parts, one in the front of the hypothalamus and the other in the middle. The former is in charge of decreasing our temperature, while the latter of increasing it.

It is the receptors beneath our skin that activate the center. The receptors have two types of heat sensors, one for warmth and the other for cold. A change in temperature, even in an extremity like the toes, is immediately reported to the center, which switches the system on. If the body temperature needs to fall, then the perspiration mechanism is switched on. To do this, the temperature inside the body is first transferred to the skin. The most important process at this point is the expansion of blood vessels, which induces a heat transfer. If the body temperature needs to be raised, the vessels are contracted and shivering is induced.

Adjusted for all conditions

Our thermostat is programmed to make maximum use of our body temperature and make adjustments depending on our age, whether we are asleep, hungry, ill, and according to weather. The required amount of energy is different for babies, children, teenagers, and the elderly. The human body needs energy less during sleep and more during an illness.

No one’s body temperature remains at the same level at all times. Our body temperature is unique to us, just like our fingerprints, and it can be measured through precise measurements. The factors that affect our body temperature may be as diverse as what we eat, what we do, what we wear, our mood, our hormones, and the environment. The increase in an adult’s body temperature due to activity is less than that of babies and children.

Our body has a temperature cycle which changes throughout the day. When we wake up in the morning, for example, our body temperature is 0.5 degrees lower than it is during the day. It is at its lowest in the second half of the night. It is highest between 16:00-18:00. We have greater heat exchange in cold weather than in hot weather. The heat regulation center adjusts temperature in response to all these changes, and thus saves energy.

Our temperature changes according to our gender, too. Body temperatures obtained from mouth measurements have shown that they may change by ±1.4 degrees in women and by ±1.2 in men. Hormones also play a role in this difference. For example, women have unique body temperatures during their period and pregnancy.

The temperature of the organs

Some parts of our body and some of our organs require different temperatures. The warmest organs are at the inside: the liver is 41.3 degrees on average, for example. Our skin is 33 degrees, and the parts near the skin have relatively lower temperatures. The temperature of the inside of our mouth, for example, is lower than that of our skin. The temperatures in the armpit and in the ears are likewise different. The thermoregulation center also has an impact on the rates of the chemical reactions taking place at the cellular level, as it keeps every one of the organs working at optimum temperatures.

There is incredible wisdom in how our body is heated (or not). Body parts that interact with the outside world have lower temperatures. One of the advantages of this is that it maintains optimum energy consumption. The higher the temperature difference between two objects, the easier the heat exchange. If our skin were as warm as our average temperature, i.e. 37°C, we would lose more heat at higher rates.

Furthermore, our eyes are granted a very special mechanism. The eyes, almost 90% of which are water and whose surface must be kept moist, are in constant contact with the outside world. However, the eyes of people who live in cold climates, where the temperature can reach -50°C, do not freeze because the eyes are placed in a protective shelter and wrapped in muscles, lipid layers, and eyelids. What’s more, capillaries, which are extensions of the ophthalmic arteries that encircle the eyes like a web, carry warm blood to the eyes regularly. Additionally, the fact that tears are salty lowers their freezing point.

Temperature balance in other living things

Animals also have body temperatures ideally programmed for their functions. The hedgehog, for example, has a body temperature of 36°C, but it is dropped to 6°C during hibernation. The body temperatures of most mammals are kept at about 37°C.

Animals are similarly endowed with systems of temperature cycles as required by the climatic and environmental conditions in which they live. For example, the body temperature of the oryx, an African antelope, can rise to 45°C when it is on the run. It can withstand such a deadly temperature thanks to the perfect system that protects its brain. The oryx has a peculiar network of vessels at the lower side of the brain which decreases the body temperature due to heat loss caused by evaporation. The carotid artery separates into smaller veins in the sinus cavity before it carries the blood to the brain, which causes the blood to lose heat. When the blood reaches the brain, it is already cool enough for the brain to function properly.

The creation of such systems certainly are miraculous, and yet we never think about them. All of our needs are met without our knowing about it.  

Are cities the same as water? It’s possible to look at chemistry for new understandings of social dynamics.

The universe is a field where existence is transformed from state to state. The transformation of matter from one state to another is generally called a “phase transition” and each phase has its own characteristics. A phase transition is possible via the alteration of some parameters and variables. For instance, heat is one of the parameters required for the transition of ice (solid) into water (liquid) and later into vapor (gas); the increased heat causes ice to change states. The characteristic feature of each phase (ice, water, and vapor) is unique. For example, ice has a certain volume; however water and vapor take the shapes of their containers. In contrast to ice, water and vapor have flowing properties.

In a similar way, if the temperature of a ferromagnetic material displaying magnetic properties is elevated, at a certain temperature, it is observed to lose its magnetism; this is called the “Curie point.” In some materials, such as some solutions, the transition into different phases can be achieved by adding solvents.

Seasons can also be considered different phases. Each season has its own specific traits and features. Seasons are generated by the alteration of the angle between the axis of earth and its orbital plane.

As these examples show, the universe resembles an erase board where continuous transitions are taking place, new sentences are being written, and existing writings are dismissed to form new sentences with new meanings.

In a recently completed academic study, a new definition of a phase transition encountered in social life has been made and this phase transition is called “freezing by heating” [1]. It is well known in daily life that the less individuals are informed about their temper and the direction they are headed, the weaker the efficiency of cooperation among individuals. If people in a unit or group behave irregularly, a dead end or bottleneck could occur. Solving dead-end problems and bottleneck situations, or preventing them before they happen, is among the topics scientists study today. In Figure 1, cases showing the traffic stream of people moving in opposite directions obtained in this study are displayed.

It is stated that there is less “noise” in situations in which there is a reduced amount of irregular behavior taking place. The term “noise” is used to define concepts that can be disruptive human relations. The higher the noise, the more the degradation of human relationships, and as a result, a disruption or even an arrest (freezing) may happen regarding social events. The elevated temperature of a melting solid material provides it with the properties of a fluid, whereas in social events, an increase in temperature ends up with a jam and freeze in social life. In Figure 1a, a pedestrian traffic flow in which there is less noise present – in other words, a situation that characterizes ideal relations among people – is displayed. Here, it is observed that people with yellow marks have a stable flow towards the left and those with red marks move towards the right side. They do so via lanes of people going towards both directions. A stable flow indicates that the system is not frozen (not in an arrest), or free of a bottleneck. In such a flow, relations work in such a way that fluidity results.

Figure 1

An intermediate noise level causes an increase of irregular behaviors (in other terms, unpredictable human behavior) and shows the presence of serious problems that are experienced regarding the relationships among people. The corresponding situation for this case is shown on Figure 1b. Here, the pedestrian traffic is now jammed and the flow is almost halted. It is impossible for lanes to form since irregular behaviors are above a certain critical level. For a system to be rescued out of this state, oscillations of sufficient magnitude are necessary.

If the situation in Figure 1c occurs, forming a vertical interface (please note the vertical interface that separates people going left and right), this case is called a “frozen state” and much bigger oscillations are required to get out of this state. Figures 1a, 1b, and 1c exhibit before our eyes how elevated noise affects pedestrian traffic: an increase of the noise in the system (for instance, an increase in the number of people who do not stop at red lights and do not continue on green) changes it from a fluid phase to a frozen one, resulting in gridlock. It is possible to compare the increased noise of the pedestrian traffic to an increase in temperature; the elevation of temperature also causes an abundance of irregular movements inside matter. Just like that, the rise of heat in a society due to a particular issue (like turmoil or other problems) may generate an increase in chaotic behaviors. Let’s try to explain this with certain events happening right now.

Let’s think about motor vehicle traffic in any city. If every individual driver observes the rules of the road, this means a low temperature – less noise, and little traffic. Fluidity is present here. On the contrary, if there is not any consensus in terms of traffic rules among the citizens – in other terms, if majority of the people are failing to abide the rules – there will be “heat”; the noise will be high, and there will be a traffic jam. If drivers cannot assess the rules at a four way intersections, or if people with no knowledge of red, yellow, or green lights are driving, a city will have a major problem with traffic.

When a freezing event takes place, waiting becomes inevitable. Unfortunately, most people don’t like waiting. Thus, such “freezing” events should be avoided, so as to keep citizens happy. For example, public announcements of road closures due to scheduled road works limit the reactions against traffic problems on certain routes. However, if traffic is announced and no reason is given, people might still be very unhappy.

For a second example, let’s consider a judiciary system. Just like the example of motor vehicle traffic, the presence of irregular moves independent from rules can lock a legal system. If laws are insufficient, or existing laws are not universally implemented nationwide, or the laws are executed and interpreted differently according to individuals, it is inevitable for a bottleneck or a freeze in the legal system. Actors within the system may anticipate a “freeze” about to happen. People in a state of anticipation need to be convinced and satisfied pertaining to legal practices. Otherwise, they may not enforce the laws properly, and legal chaos may ensue.

Freezing by heating may also apply for certain economic processes. Some economic uncertainties or some actions of unknown cause can be considered as noise by elements of the economy, thus enforcing a behavioral change that is able to affect the entire economy. Therefore, any applied change is followed carefully by the actors of the market and these actors must be satisfied about the changes taking place. Higher noise levels and dissatisfaction of members who are waiting affects the liquidity of the market and can lead to the withdrawal of funds. Withdrawal of money negatively impacts the parties who are in need of cash in various ways and the economic system gains momentum towards a “frozen state.” Negative factors are not the only reason for a bottle neck. Conservation of balance and the fluidity of the economic system are considered as the essence of this issue.

The principles briefly given above can also be applied to socio-psychological events. It is impossible not to encounter a bottleneck for a society consisting of members who are aggressive, stressed, or have less knowledge of their destinations. If a decision can be made with a peaceful state of mind and there is no doubt present regarding current practices, patience becomes the most important parameter. Hence, until a state of balance is established, it is advised to wait with understanding and patience. Patience is a healing aid that plays a role in reducing the temperature in all bottleneck situations.

Fasting prayer is very important for people in terms of gaining this habit. Even for a person who observes fasting one day or two in a week, it becomes more possible to deal positively with any bottleneck situations encountered that week. Another way to lessen the impact of a bottleneck is living to be aware of the fact that each event may serve a purpose. As Nursi stated, each negative or positive event that has been experienced has a purpose. Every event will be over once its purpose is reached. For a sincere believer who is aware of this, realizing that patience also means to appreciate time; thus, it is possible for him to disperse the negative elements that this waiting will bring.

It is possible to expand the “freezing by heating” phase transition to various different mediums across many other disciplines. However, the only necessary element in all of them to prevent such freezes, or to break present freezes, is the reduction of noise (temperature). It’s possible to find guidance by acknowledging that this world is a place of wisdom and service, and rewards do not always come in this life.

References

1. Dirk Helbing, Illes J. Farkas, Tamas Vicsek, “Freezing by Heating in a Driven Mesoscopic System,” Physical Review Letters 84, 1240-1243 (2000).
2. H.Eugene Stanley, “Non-equilibrium Physics: Freezing by Heating,” Nature 404, 718-719 (2000).

Fuel cells are very promising chemical energy conversion devices. Though the first fuel cell was made by William Grove in 1839, they’re just now being explored as a real energy alternative (1). Let’s take a look at how they work: in a fuel cell, electricity is generated by the reaction of hydrogen and oxygen, which forms water. They are similar to batteries and internal combustion engines (ICEs): just as in a combustion engine, where fuel is oxidized, the oxidization of hydrogen generates energy. They’ll work as long as fuel is provided.

Despite these similarities there are some differences that make fuel cells more attractive than batteries and ICEs. A fuel cell works more efficiently and quietly than engines do. When hydrogen is used as fuel, power and drinking water are produced as by-products (2). Having safe by-products answers our concerns regarding older power sources. A battery is dead if it is not re-chargeable; however a fuel cell can be continually reused.

Fuel cells are generally defined by the type of electrolyte used in the cell, and they operate at different temperatures. Alkaline fuel cells (AFCs), proton exchange membrane fuel cells (PEMFCs), and direct methanol fuel cells (DMFCs) are called low-temperature fuel cells. Phosphoric acid fuel cells (PAFCs) are an intermediate-temperature fuel cell. Molten carbonate fuel cells (MCFCs) and solid oxide fuel cells (SOFCs) are called high-temperature fuel cells (3, 4).

They have been mainly used for stationary, transportation, and portable applications. Since the need for electricity in daily life has dramatically increased, reliable and efficient power supplies have become necessary. Over 2,000 stationary fuel cell systems have been built in hotels, schools, and hospitals. Stationary power generation is considered more commercialized among the other fuel cell applications. Today, these systems have reached an efficiency of 40% when a hydrocarbon is used as fuel. Fuel cell systems are also used in telecommunication systems, and these cells provide power between 1 and 5 kW (5).

Fuel cells have been identified as the most probable alternative power source for transportation applications in place of internal combustion engines (ICEs). There are two distinct features of fuel cells that make them a better choice than ICEs. First, their carbon dioxide gas emissions are nearly zero. Second, fuel cells are much more efficient than ICEs – about two to three times (6). Ballard Power Systems have been developing zero-emission-vehicles by using PEMFCs, which have low operating temperatures and a higher power density.

NASA decided to use fuel cells on American spacecrafts in the 1960s. The advantage of using them in spacecraft was that while they were generating electric power, they produced drinkable water for the astronauts. A fuel cell was used as an integral part of the power supply PEMFCs (1kW) in the Gemini crafts and AFCs (1kW) in the Apollo crafts, both of which were a part of NASA’s human spaceflight programs (6).

Portable applications of fuel cells offer electrical power when reaching the electrical grid is not possible. When they are used as power sources outdoors, they help to avoid air and noise pollution (4). Because these portable fuel cells are lighter and more durable than batteries, they have been considered as alternative power sources for mobile phones, laptop computers, and some electronic devices (5). They are also used by the military in battle. A 4 kW PEM generator was built for the U.S. military by Intelligent Energy Ltd., out of Europe (7). Since direct methanol fuel cell systems are much lighter than the indirect systems, they are mostly used as portable power systems.

Although fuel cells have benefits when compared to other power sources, they are not widely used because of their high cost. In 2010, the Energy Information Administration released that the cost of fuel cells is $6.83 per installed watt, which is almost 7 times more expensive than a natural-gas turbine generator plant (8). In 2008, the Honda Clarity produced one of the first hydrogen-powered automobiles; these require very expensive catalysts: platinum (9). A catalyst makes the chemical reactions occur faster. Platinum is still the best catalyst, so this explains the prohibitive cost. A cheaper substitute for platinum is needed for use in automobiles. Another problem is that hydrogen is widely used as fuel for transportation applications. Until there is a sufficient hydrogen infrastructure, car manufacturers will find it hard to mass produce cars that use fuel cells.

Cetin is a freelance science writer.

References

1. Grove, W. R. (1839). On voltaic series and the combination of gases by platinum. Philosophical Magazine and Journal of Science, Series 3,14, 127-130.
2. Hoogers, G. (2003). Fuel Cell Technology Handbook. Boca Raton, FL: CRC Press.
3. Mekhilef, S., Saidur, R., Safari, A. (2012). Comparative study of different fuel cell technologies. Renewable and Sustainable Energy Reviews 16, 981-989.
4. Gencoglu, M. T., Ural, Z. (2009). Design of a PEM fuel cell system for residential application. International Journal of Hydrogen Energy 34, 5242-5248.
5. Andujar, J., Segura, F. (2009). Fuel cells: History and updating. A walk along two centuries. Renewable and Sustainable Energy Reviews 13, 2309-2322.
6. Iovine, John. “Fuel Cells.(composition, energy-generating processes and industry developments and innovations).” Poptronics. Poptronix, Inc. 2001. Retrieved May 17, 2012 from High Beam Research: http://www.highbeam.com/doc/1G1-69015426.html
7. Cowey, K., Green, K., Mepsted, G., Reeve, R. (2004). Portable and military fuel cells. Current Opinion in Solid State and Materials Science 8, 367-371.
8. Administration, U. E. (2010, November). Updated Capital Cost Estimates for Electricity Generation Plants. Retrieved from http://205.254.135.24/oiaf/beck_plantcosts.
9. Muller, R. A. (2012). Energy for Future Presidents: The Science Behind The Headlines. New York: W.W. Norton Company, Inc.

We tend to overlook our skin, but it performs many vital functions for our bodies – including coming to our rescue in emergencies.

Since it is designed to function within very precise limits, our body is very susceptible to small temperature changes. Since abnormalities in these changes occur, the body has various mechanisms to keep its temperature constant. One of these mechanisms works by changing the amount of blood in the veins underneath the skin. When talking about body temperature, it is important to distinguish between the internal and external body temperature. The internal temperature is the temperature of the brain and internal organs, while the external body temperature is the temperature of the skin.

Normally, arteries that transport clean blood, and veins that carry dirty blood, are not connected; therefore clean and dirty blood never mix. However, as a consequence of some illnesses or birth defects, an abnormal bridge between arteries and veins may be present. This kind of condition is usually called arteriovenous shunts, or arteriovenous fistula. In these kinds of situations, blood is pumped directly from arteries to veins. In other words, clean blood flows towards dirty blood. Normally, the clean blood has to travel the body, providing oxygen and other supplements to cells, while collecting carbon dioxide and returning to the heart to be cleaned again.

An incredible network for the transportation of substances from the blood in arteries and veins has been created. If this system, known as the “capillary network,” did not exist, none of our organs could be fed, and the circulatory system would not be able to provide its vital function.

The system is necessary for two reasons. The speed of the blood in the arteries and veins is too fast for anything to be transported to the organs, and their walls are too thick to allow transportation of substances. Therefore, the blood travels from the arteries to the capillaries, and after the trading of oxygen and other substances with carbon dioxide is completed, it flows to the veins. If any kind of abnormalities exist, the blood flows directly from the arteries to the veins, therefore skipping the capillaries. As a consequence, the organs aren’t fed and the blood gathers in the veins without fulfilling its purpose. Naturally, the oxygen and nutrition balance of the organs gets messed up. The blood is pumped out of the heart with no purpose and heart failure becomes inevitable.

The capillary network has been assigned the task of communication between arteries and veins. The skins is our only organ where the blood flows directly from arteries to veins; AV shunts accomplish a very important duty in this function.

There is a network of veins underneath the skin. The number of veins in this network is so many that if they were completely filled up, they could hold up to two liters of blood in the skin. Blood is pumped to the skin for two purposes: to provide oxygen and nutrients to the cells, and to collect carbon dioxide and waste products in the cells, as is done with every organ; and to monitor the internal temperature of the body by sending blood to the skin if the temperature gets too high, similar to what radiators in cars do when the engine gets too hot.

There is also the subcutaneous fat tissue underneath the skin which acts as an insulator. The vein network mentioned above is inside this fat tissue. There is a continuous flow of blood from the capillaries that feed the skin towards this network of veins. Moreover, especially in areas where the skin is exposed – such as the hands, feet, face and ears – there is a blood flow from the small arteries towards this network of veins. Contrary to other organs in the body, blood flows directly from the arteries to the veins. If this direct blood flow did not exist, the amount of blood in the skin’s veins would be close to zero, because the amount of blood necessary for skin nutrition is very little. However when the internal temperature rises too much, the amount of blood, which is normally close to zero, can suddenly increase to as much as 30% of the blood pumped by the heart. In this case, the body’s internal temperature is being transported to the skin. This is an incredibly efficient cooling system. However, if the weather is cold, the AV shunt veins are switched off and the skin’s blood flow is decreased until close to zero, therefore maintaining internal temperature. The fat tissue underneath the skin also has a very important function, as it acts as insulation, helping maintain temperature.

Body temperature and the body’s systems work in perfect coordination with each other. We can observe a very simplified version of this system in computer based air conditioners. However, when we reflect upon the incredibly sophisticated cooling system of the human body, we come to the conclusion that no other system is as perfect as that.

The hypothalamus, which has various vital duties for the brain, was also given the very important mission of controlling the body’s temperature. There are hot and cold heat receptors in various parts of the hypothalamus. When body temperature increases, these receptors are activated. As a consequence of this warning, skin veins all over the body expand. Simultaneous with the expansion of the veins, sweat is excreted.

The hypothalamus also has the duty of suppressing the mechanisms that produce heat throughout the body. For example, trembling is stopped and general metabolism is slowed down to decrease body temperature. As metabolism slows down, the production of heat becomes minimal, and cooling takes place. In conditions where the body temperature is too cold, some hormones secreted in the hypothalamus trigger the pituitary, and then the thyroid, hormones. Since thyroid hormones are responsible for increasing metabolism, body temperature increases. However if body temperature increases above normal, the control of the hypothalamus on the thyroid is reversed, and thyroid hormones are decreased, therefore decreasing body temperature.

There is one more reason for placing so many veins in the perfect and miraculous body’s skin: except for extremely cold weather conditions, quite a large amount of blood exists in these veins that are not used for nutritional purposes. Some of our organs act as storage for blood; two of the most important ones are the spleen and liver. Another one is the skin. In the course of losing blood, or an illness that increases the need for blood, the spleen and liver shrink. As a consequence of this shrinkage, the blood inside them is sent to the heart, through veins, and distributed to the areas in need of blood. This increases the heart rate.

A similar scenario occurs in the skin. The veins responsible for cooling shrink, and the blood they contain is sent to the heart with the help of the main veins, therefore helping the heart pump. During heavy loss of blood, the blood in the skin comes to the rescue. Patients who are losing blood have incredibly cold and pale skin. This is because the blood in the skin has reduced to a minimum.

The obverse of this happens in an illness called erythromelalgia, where more blood than normal flows from the arteries to the veins in the skin. This is mostly seen in the hands, feet, nose, and ears, since AV shunts are more prevalent in these areas of the skin. The symptom of this illness is burning pain, which is triggered by heat and soothed by cool temperatures. The nutrition of the skin decreases and some substances produced because of the absence of oxygen increases redness, heat, and pain, since some of the capillaries feeding the skin shut down and all of the blood flows from arteries to veins with the AV shunts.

Our skin protects our muscles and bones, and contributes to the beautiful aesthetic of our body. It provides our sense of touch, and is therefore a means for us to experience the material world, as well as providing temperature control for our bodies. It can clearly be seen that the relationship between the skin and the veins could not have evolved by the consequence of coincidence.

By examining the heart of a crocodile, researchers have discovered how it is that an air-breathing land animal can manage to glide through murky waters for several hours without the need to surface.

There is that one scene in documentaries that we often come across on television: Crocodiles gliding gracefully inside the water, waiting for hours for the perfect time to pounce and snatch their prey from their necks and into the water. But how do these animals manage to stay underwater for almost two hours without surfacing for air even though they, just like human beings and other land animals, live on pulmonary respiration and are in need of the free oxygen in the air?

A member of the reptiles class, crocodiles do not have gill nor can they have skin respiration since their skin is covered with a thick and airtight keratin armor. Just as every living organism are provided with a suitable anatomic and physiological character for their survival, crocodiles are also granted with a system that facilitates their long stay in the water.

Crocodiles are bestowed with a special heart anatomy different to other reptiles like lizards, tortoises, and snakes. The hearts of other reptiles are designed to contain three sections including two atriums and one ventricle. The right atrium, which collects the returned oxygen-deprived (deoxygenated) blood and the left atrium which collects the oxygen-rich (oxygenated) blood retrieved from pulmonary arteries of the lung, transports the blood to one common ventricle. Because there is only one ventricle to receive and combine oxygenated and deoxygenated blood, a mixture of less oxygenated blood is pumped to their body. Depending on outside temperature, the body temperature of a reptile increases or decreases. Their metabolism slows down, almost to a halt, while their body temperature decreases when outside temperature drops near or beyond freezing conditions. Hibernation begins as a result. Frogs and reptiles stop hibernating as soon as their body temperature increases depending on the outside temperature when the weather gets warm. These organisms are called cold blooded animals (with variable body temperatures) because of this feature.

The heart of a crocodile is different to other reptiles in that it has four chambers just like birds and mammals. Blood is sent to the lungs for gas exchange from the right, and from the left ventricle it is pumped to the body. Thus the two types of blood do not mix in the heart. However, what is interesting is that blood is mixed as soon as it leaves the heart via a valve (foramen of panizza) placed in between the right and left aorta.

What could be the purpose of blood, which does not normally mix in the heart, mixing through the medium of a hole? Does this opening in between two aortas indicate a flaw? It is understood after some research that this hole in fact is not a flaw or an anomaly; on the contrary, it is a necessity for a metabolism suited perfectly to the lifestyle of the crocodile.

Warm blooded vertebrates like birds and mammals with a four chamber heart have faster metabolic speeds and higher blood pressures. For these organisms can only supply the energy they consume during their daily activities via such a fast metabolism and a high level of oxygen provided with oxygenated blood.

If the metabolism of a crocodile was fast like mammals all throughout the year, it would have to continuously be nourished and use oxygen. Furthermore, because crocodiles do not have much predators, they could have also lead to the extinctions of some species by overpopulating if they featured a faster metabolism. The low ratio of heart-body mass in crocodiles (0.15%) compared to mammals and birds (0.40%-0.50%) cause the movements of crocodiles to be relatively slower. The Almighty, who creates everything with his wisdom, lowers the blood oxygen ratio and the metabolic speed of crocodiles by creating a valve that combines the two aortas. Thus eliminating the possibility of crocodile overpopulation.

Crocodiles have two aortic arches whereas mammals only have a left, and birds have one right aortic arch. The left aortic arch, despite some contact with the returned blood via foramen of panizza, delivers the oxygenated blood towards intestines, stomach, spleen and the liver after receiving it from the left ventricle of the heart. This is because the digestive system of a crocodile requires oxygen-rich blood. Deoxygenated blood while exiting the right ventricle goes towards the pulmonary arteries of the lung for exchange and mixes with oxygenated blood coming from the right aorta, feeding other organs that are instrumental for its slow metabolism.

Under the water, separated oxygen-rich and oxygen-poor blood mixes when exiting the heart and switches route, thus making oxygenated blood vessels start to carry oxygen poor blood. So what is the reason behind this switch in the direction of the bloodstream under the water? See at this point, the extraordinary features of the crocodile blood circulation system kick in. The two anatomical features belonging only to only crocodile hearts is what enables them to stay under water without breathing. Because of little or no lung use under the water, a big portion of the blood stream is diverted away from lungs; therefore oxygen poor blood is pumped back to the body. As one feature of the two, foramen of panizza restricts (does not close) upon signals coming from nostril sensors under the water but expands and remains open on land. The two aortic arches connects with each other via foramen of panizza as soon as they leave the heart but merge completely in the lower parts of the body away from the heart (anastomosis).

The second feature stems from a serrated valve. Refilling of pumped blood is stopped via a passive, thin leaf-shaped valve which is located at the tip of the pulmonary artery exiting the right ventricle. Thus, one-way direction of blood flow in the heart is maintained. These valves, which carry nodules made of connective tissue, constrict during the dive and blood flow to the lungs is reduced greatly. Therefore blood rejoins the systemic circulation from the right aortic arch.

The blood circulation of crocodiles is similar to birds, mammals, and humans while they are active on land. Oxygen-deprived blood is sent to lungs for gas exchange. The only difference is the turning of the right aorta to the left and the left aorta to the right. Oxygen rich blood not only flows through the left aorta but also through the right aorta via foramen of the panizza as well causing distribution via two channels into the body. However, the foramen of the panizza being open is not sufficient for these two channels to be used. At the same time, the pressure of the blood within the left ventricle needs to be higher as well. This way, high pressure oxygenated blood flows into the right aorta through the opening of the panizza, applying pressure to the valve at the tip of the right aorta to close it in order to prevent the mixing of the oxygen-poor blood into this route. As a result, oxygenated blood gets distributed quickly by each aortic arch without mixing with the used blood. Thus, oxygen-poor and oxygen-rich blood follows the following route on land

* Deoxygenated blood: Body – superior and inferior pulmonary veins – right atrium – right ventricle – lung pulmonary artery – lungs.

* Oxygenated blood: Lung pulmonary vein – left atrium – left ventricle – right aorta and left aorta via panizza valve (both aortas are active) and body.

The opening of the panizza narrows with the help of signals coming from the nostrils when crocodiles submerge. At the same time serrated valves at the tip of pulmonary artery that transports the blood to the lungs also constrict. While this serrated valve is at work, a majority of the blood returning from the body is not sent to the lungs because they are not functioning at the time. This serrated valve also increases the pressure of the right ventricle. This pressure, along with elevated resistance in pulmonary circulation and lowered pressure of systemic circulation, leads to the opening of normal valves at the tip of the left aorta. In the end, the left aorta which normally carries oxygenated blood on land starts carrying oxygen deprived blood, and there is a route switch.

The most beneficial part of this switch is to re-route the deprived blood back to the body via a different route, that is, the left aorta. This by-passes the lungs and prevents time loss. Despite the fact that blood of the left aorta mixes with the oxygenated blood of the right aorta to some degree via the panizza valve, the main function of this opening while submerged is to supply blood flow to the arteries feeding the heart and brain through the transfer of some poor blood from the left aorta into the right aorta; this way vital organs are not left without blood.

Blood returning from the body is not sent to the lungs for gas exchange when crocodiles are under the water. However, existing oxygen in the blood can be delivered to the tissues quickly by a route switch. The amount of bicarbonate ions that is important in the transport of CO2 in the blood increases when oxygen pressure in the tissues drop. Anaerobic respiration of tissues increases. This leads to an increase in lactic acid levels and reduces pH. Eventually, it facilitates the release of oxygen carried by hemoglobin. In the end, oxygen that is bonded with hemoglobin is used more efficiently. In the meantime, the body temperature of a crocodile submerged under water decreases and slows down its metabolism, reducing the need for oxygen. Oxygen stored in the blood can be sufficient up to two hours under the water. However when these reserves are consumed, crocodiles have to resurface to breathe even though it may cost a prey to escape.

Crocodiles can live on land and in the water and adapt to their environments with ease and efficiency thanks to the ponderous working of their mechanisms under water, the change in blood circulation, slow blood flow, reduced body temperature and metabolic speed bestowed upon them. Just like humans in sleep, crocodiles can remain submerged for long periods (4-6 minutes in usual dives; up to 2 hours when pressed) with this perfect system granted to them. Crocodiles use these mechanisms not only when under water, but also while resting or for periods after heavy feeding.

If we try to fill a glass of soda without letting it overflow, we usually notice the bubbles or froth of the drink. As we fill the glass, bubbles form on the surface and these tiny bubbles grow. Reaching a certain size, the bubbles escape from the liquid surface, and vanish into the air. If we put our finger, or a straw into the soda-as most of us did as children- we immediately notice that tiny bubbles of gas form on the object immersed in the glass. Just like in the freezing of water or in the escape of gas from soda, a precise energy exchange occurs at the initial stage of any phase transformation. Completion of any phase transformation – freezing or condensation (clouds transforming to rain)- is impossible without such precise energy exchange. The fact that all these phase transformation occur with precise energy calculations in the best possible temperature ranges to support life is a clear proof that nothing in the universe was created by mere coincidence, and that everything occurs by the command of the Almighty.

We know that everything in the universe obeys the minimum energy principle. If we want to freeze water, all we have to do is to cool it to a temperature below 0°C, and the transition from water to ice begins. Water molecules tend to gather together to form clusters. When five to ten of these molecules bond together, however, a difficulty is encountered. The formation of solid-liquid, solid-gas, or liquid-gas interfaces requires a specific amount of energy. In the beginning, the surfaces of these clusters are quite large as compared to their volumes such that the energy they receive to form an interface is much greater than the energy they release; therefore the state of minimum energy is not reached. To explain this to you in another way: let us assume that we manufacture beads for the production of costume jewelry and garments, and the surface of the beads requires treatment. If the beads we manufacture are smaller than the specific size, they will be more expensive to treat, and therefore will not cover the costs, so only producing beads exceeding the specific size will be profitable to the manufacturer. The main aspect here is actually the size of the beads, so if manufacturing beads which exceed the specific size is simpler and more profitable, rejecting the beads smaller than these specifications would be inevitable.

As in this example, because of their high energy value, the molecular clusters formed initially (embryos) return to a liquid form. Then once again the particles begin to bond, but again the result is the same. An embryo must grow to a certain size for its surface area to decrease in comparison to its volume and thus reduce its energy. This is only feasible when many atoms bond, for only when a sufficient number of atoms join together does the embryo transform into a nucleus, and then begin to crystallize and eventually become solid. The process called homogeneous nucleation is only possible under certain conditions: the liquid must be at a temperature of around –40 C^o for both the transition in the balance of energy, and for the water molecules and atoms to become solid and bond to form a nucleus. If we contain pure water totally motionless in the deepfreeze at approximately –8 C^o, we will have supercooled water that has not yet transformed into ice; the temperature between the nucleation and the freezing points, is called supercooling. Supercooling is a metastable condition where liquid or gas remains supercooled without actually becoming frozen, but the slightest intervention or movement can cause the substance to transform into a solid. The tiny bubbles of carbon dioxide in soda is also in a metastable condition, for as soon as the bubbles have the opportunity, they escape from the liquid and vanish into the air. If we immerse a straw or finger into a glass of soda, this forms an added surface, which also facilitates a solid-gas interface, and if we add a teaspoon of sugar to the soda, this induces the drink to froth and bubble at great speed. Water boiled in a saucepan actually nucleates on the wall of the container.

Supercooling is a metastable form of the substance. Every substance or solution has a specific temperature value for cooling. For instance, liquid copper transforms into a solid at 1083 C^o. Homogeneous nucleation requires the bonding of 310 atoms, and supercooling to approximately 236 C^o.

Under normal conditions, substances which have more than one type of molecule undergo phase transformation known as heterogeneous nucleation. In this case, the atoms form primarily on the walls of a container on particles of impurity, or minute solid particles in the liquid, and this significantly reduces the surface energy barrier for nucleation. So for a moment let us return to the bead example. We have discovered that instead of directly manufacturing smaller beads, it would reduce the costs of decorating the surface of the beads to coat and treat larger beads, so the beads are being produced in this way, thus reducing losses.

Supercooling can occur at temperatures even as high as 2–3 C^o, and this is very important. The condensation of water or supercooled water droplets in clouds must reach a specific size and weight in order to fall to the earth as raindrops. Here, the solid microscopic particles combine to form nuclei. Even if the clouds are much lower in temperature, rain cannot form without nuclei. Particles of salt which escape from the sea, sand that rises from the desert, the sulphate released from the ashes of volcanic activity or minute atoms of dimethyl sulphate emitted by certain planktons are driven into the atmosphere by the wind and form nuclei. As the Almighty, the Creator of the universe revealed in Al-Hijr, verse 22 of the Qur’an: “And We send the winds to fertilize, and so We send down water from the sky, and give it to you to drink (and use in other ways)” indicating that one of the duties of the wind is fertilization. Even the particles in smoke released irresponsibly by humans from industrial chimneys, or from car exhausts form nuclei that eventually transform into rain.

During the foundry process, solid substances are added to liquid metals for certain purposes, such as enabling metal to set more rapidly, or increasing the metal’s durability. When liquid metal is cooled, its atoms form nuclei on microscopic solid impurities. These nuclei increase in size and assemble into groups called grains. The irregular zone between these groups is known as the grain boundary. The grain boundary forces the compressed atoms to move and weld, thus increasing the durability of the metal. This method known as infusion or grain contraction ensures an increase in the formation of nuclei, and also in the durability of the metal. Cloud seeding, a topic which mainly comes to light when there is a lack of rain, is actually inducing the clouds to form artificial nuclei that will in turn produce rain.

Some creatures on earth protect themselves with mechanisms bestowed by their Creator, and one of these creatures is the wood frog. As the water in its cells begins to freeze, the antigel protein found in its blood surrounds the formation of nuclei, and prevents the nuclei from increasing in size. The frog remains frozen and motionless until the temperature increases. If we touched a wood frog in this condition, its cells too would freeze suddenly, and the frog would die. It is impossible for a frog to know how to cool to the point of freezing, and nucleate. It is also impossible for a frog to adapt to such a mechanism because this would require practice and experience, which would of course be deadly. Therefore, is the frog’s ability to freeze, and its process of nucleation not a clear indication of the providence and blessing of God the Almighty?

I am the barrier between your body and the outer world and I am responsible for this area. I can sense every change in the outer world, including heat, cold, humidity, pressure, various radiations, and the effects of many harmful chemicals and physical phenomena. When I become aware of the presence of something that is harmful, I warn your organs to act according to these changing conditions. That is why everybody knows me primarily as a sense organ.

However, in addition to being a sense organ, I have many other important duties; however, if I were to list them here, this article would take up the entire magazine. In order to ensure your good health I have to carry out my duties, be they aesthetic, protective or metabolic, perfectly. Even if you only examine my appearance, you will see how beautiful I am. You should visit an anatomy laboratory one day and watch the medical students performing an autopsy. Examine the cadaver whose skin has been pulled back to allow the students to study the internal organs. Look, if you can! Although the body is miracle, if the skin is not present, it would lose its splendor and become ugly and horrible. The beauty and meaningful existence of all the other organs are only complete with me. Our Lord God Almighty has created me and dressed you with me as a garment that fits each part of your body. He has lined your palms and soles with a thick outer lining made of keratin; this enables you to walk and use some hand tools easily. If on the foot or hand I were as thin as I am in the lip area, then I would easily get punctured and injured while walking or using a tool. God has created special joints where your fingers and toes join the feet and hands. These joints allow your fingers, hands and feet to move in many different ways. In order to protect your head from the sun and cold God has changed some of my cells into hair and has given it the ability to grow constantly. God also protects your eyes with special hairs that we call eyelashes and eyebrows. With these He also completes the beauty of your face. However, these do not grow constantly like the hair on our heads. Just think, otherwise you would have to trim both your eyebrows and eyelashes everyday in order to see. The special hairs in your nose and ears help prevent the entry of harmful particles, like dust or harmful microorganisms. You may think “How important is that? Just a few strands of hair?” Of course, hair is not the most important thing of all, but is life nothing more than staying alive? Of course not! There is also an aesthetic aspect to life. We can understand this if we look at a person who has no eyebrows or eyelashes! Certainly, God has made human beings beautiful creations and the hair is an important part of this beauty. As with everything He does, the significance of the hair is much more meaningful than when first seen.

In addition to my aesthetic beauty, I should also tell you about my protective functions. My first and most vital job is to balance the level of liquid in your body and to prevent its loss. The liquid level and the amount of minerals inside your body are very important. If it were not for me your kidneys would not be able to regulate the level of these liquids. It is for this reason that people who have burns that take up two-thirds of their skin or more cannot live; the water loss in their bodies is too great. In burn care centers, they try to control the loss of liquids using very sensitive devices; however, with serious burns this is usually unsuccessful. My protective functions are not limited to liquids; I also protect your body from all kinds of bacteria, funguses and viruses. As you know, your skin can get inflamed and infected from even a thorn. If the skin becomes damaged or broken over a large area you could face serious infections. This is because if I am not present many microorganisms will invade your body and make you ill.

Your body is very sensitive to heat and cold. The temperature of your inner body normally should be between 370C and 38 0C (96.8 0F and 98.6 0F); if it increases above this temperature, then you are unwell. If you remain for a long time in cold conditions and your inner body temperature falls off, many of your organs, especially the lungs, stomach, and kidneys are damaged and cannot work properly. You could die if the temperature is too low for too long. And in contrast, if you stay too long in the heat and your inner body temperature increases, your nervous system can be damaged, as the brain is very sensitive. Then your heart and other organs will start to fail, which eventually results in death. Indeed, human beings live everywhere, from the deserts to the poles and everywhere people are able to maintain an inner core temperature that is constant between 96.8 0F and 98.6 0F. I play a very important part in this system. Although the main control center is the brain, it acts according to stimuli that I send and I carry out important functions when the brain responds to these stimuli. Later, I will tell you how I can both warm and cool you.

Before telling you about my other functions, I would also like to tell you about my structure, which appears quite basic from the outside. Of course, I am not simply a cover that wraps your flesh. First of all, I am a living organ that is being nourished, that grows, that is repaired and which is very flexible. As I get rid of dead cells, I replace them with new ones; I am aware of everything that happens in my surroundings and I allow you to feel the world around you. I consist of two major layers: the epidermis (outmost layer) and the dermis (the inner level). The visible layer, the epidermis, consists of cells that gradually die off and stiffen. Those cells are toughened with a protein called keratin which is absorbed inside their structure; everyday I shed dead skin cells. This is part of the “dirt” that is removed from your body with every shower. This outer layer contains bacteria, funguses or other parasites that have been transmitted from the outside world and which may cause diseases. These parasites are removed as the dead skin cells are shed. The innermost layer (stratum germinativum) of the epidermis has a great capacity for cell division and it constantly produces new cells from the bottom to the outermost level. These cells start out life as cylinders, but as they move towards the outer surface they become cubical and then flatten out. At the same time keratin is being produced in those cells, and as a result they stiffen and start to die off. When the cells arrive at the outermost level, they are already dead. Some of those dead cells do not fall off. They accumulate and combine to make up the structures that we call nails and calluses. In this way the cells protect those areas that are most sensitive or most often used.

You will be surprised to see what great biological activities take place in the epidermis. Even when a person dies, this layer does not die right away. After death the nails and beard continue to grow. This occurs because of the activities in the germinative epithelium, which makes up the basal layer of the epidermis.

Beneath the epidermis is the dermis, a relatively thick layer. This is the layer which keeps the skin lively and firm and which produces the color. Many works of arts are present in this layer to complete my splendid structure. This layer consists of connective tissue with fiber bundles that is made of collagen protein. As people get older, their skin dries up and starts to lose its collagen proteins. Once the fibers start to decrease, I lose my firmness, and then I start to wrinkle. Although people are not happy with wrinkles, which are inevitable, I don’t think this is something to worry about; wrinkles are also a sign of maturity and experience. In the structure of my dermis there are other parts that have very important functions: The sweat glands, which are in the shape of coiled tubes, spread throughout the body act as ventilators; in addition, the hair follicles, the sebaceous gland, which helps to nourish and moisturize the hair, the chromatophores (pigment-containing cells) that determine the skin color, the hair muscles that give your hair flexibility and the blood vessels that nourish me are all important. I also have special receptor cells that can sense temperature, pressure and pain and there are nerve endings scattered among these cells.

In different parts of the body I am more sensitive to particular sensations. My sense receptors (corpuscles) vary in shape and you human beings have named them after the scientists who discovered them. There is Pacini’s corpuscle, Meissner’s corpuscle, Ruffini’s corpuscle and Krause’s corpuscle. Each of those receptors is thought to be receiving independent stimuli, but this has not been proven by experiment yet.

Do you ever wonder why you and your friends have so many different skin tones? This is the result of the work of the chromatophores (cells that contain pigment) which are located in the dermis, at the point closest to the epidermis. These cells, which have a number of branches, move in relation to the intensity of the light, and their branches can stretch and shrink back. These movements cause the pigment granules (melanin granules) to disperse within the cell or aggregate towards the center. This is how they can lighten or darken the skin color, causing you to get a “tan.” The seasons, the length of the day and the intensity and duration of the sunlight all affect the movement of these cells. These cells darken your skin color during the summer and lighten it during the winter. But, why is this necessary? This is a wonderful physiologic mechanism that has so many amazing purposes and meanings. I am sure you have noticed that people who live in Northern Europe and North America have a lighter complexion than those who live in the more southerly regions of the earth. This is because the countries in these northern regions are exposed to a less intense sunlight for a shorter time. The further north you go the more rainy and cloudy it is. However, sunlight also plays a very important role in the synthesizing of vitamin D in your body. The molecule known as 7-dehydrocholesterol can be converted into vitamin D only with sunlight. Vitamin D is a fat-soluble vitamin that is highly important for calcium absorption and bone metabolism. If you do not have enough exposure to the sun, then vitamin D cannot be produced; this could result in disorders like rickets (most common), as well as several other bone diseases and skeletal complications. However, it is interesting that sunlight is a two-edged sword. Neither too much nor too little sunlight is good for you. Too much exposure to the sunlight damages my health, causing such diseases as skin cancer and eye disorders. Our Lord God Almighty has made all parts of the earth suitable for human life. He knows well, of course, what people need in order to be able to live in places that have less sunlight and in other places that have a great deal of sunlight. In order to allow people to benefit from the sunlight everywhere, He has given the necessary qualities to my chromotaphores and the melanin granules that they contain. In places that have less sunlight, my chromotaphores synthesize less melanin. The melanin disperses throughout the cells or the cells move downwards, and my color lightens. This allows more sun absorption and this sunlight is used for vitamin D production. In sunny places, however, people are more exposed to the ultraviolet rays of the sun as well as other forms of radiation. This is why the risk of my cells becoming mutant and cancerous is greatly increased. In order to avoid such a situation, more melanin is synthesized in people who live in sunny places. The melanin in the chrotaphores gathers towards the center of the cell and my color darkens. Thus, excess sunlight is absorbed by my melanin pigments thanks to their special structure and function. This prevents other sensitive cells from becoming damaged and cancerous.

During hot weather, in order to balance your inner body temperature, the blood vessels that pass through the skin expand and more blood is carried through the skin. I give off the water in my blood through my sweat glands. While this warm water called “sweat” spreads over my surface and evaporates, an important amount of heat is released into the air. Thus, your inner body temperature does not increase and you remain cool inside. Thanks to the work of my sweat glands, I can also get rid of some nitrogenous waste and thus support your kidneys. During cold weather, however, the activities of my sweat glands decrease, and this helps you to stay warm. The blood vessels narrow so that the blood in me is reduced. More warm blood is channeled into your body so that your important inner organs do not become cold. The muscles of my hairs contract and the hairs straighten, thickening the layer of hair that covers me. It feels like you are covered with a blanket. If your body temperature falls off significantly, my receptors stimulate the muscles that lie under me and these muscles produce heat by vibrating. That is why you shiver from cold! Women have fewer hairs on their body. Do you think this is unfair? Of course not! Unlike men, women’s bodies are created in such a way that they can store a greater percentage of fat among the tissues under the skin. This hypodermic fatty tissue not only protects women from cold, but it is also used as extra storage for nutrients that they use when breastfeeding. It also helps protect women’s muscles and bones against bumps and shocks from the outside. So, this tissue works both as a temperature isolator and as a “shock absorber.” There is nothing unfair about this. And, it proves that God gives each of His creation exactly what they need and deserve.

Some people say that the skin is a mirror of the body’s health; this is true. The fact that I am visible and can be examined easily makes me the first organ to display symptoms of many diseases that lie below. Abnormalities that appear on me are usually a sign of metabolism disorders, ulcers and other glandular disorders in the body. For example, if your liver is being affected by a poisonous substance, this shows up as red spots on the hands. But not only physical ailments affect, me; I am also affected by your spiritual condition. Of course, the opposite can happen, too. That is, diseases on the skin can affect your inner organs.

I have mentioned before that my ability to renew and repair myself is very great. God willing, I can repair mild burns, bruises and cuts easily under normal circumstances. However, if the bruise goes as deep as my basal layer, there might be a scare there to remind you in the future and to give thanks to God for your health. In addition, in diseases like diabetes, my ability to renew and repair myself is weakened and I cannot easily heal. In such cases, you have to take the utmost care to keep me clean so that I do not get infected.

Well Peter, I think that I have said enough about myself. I will not continue to go on about the many symptoms of diseases that can be seen on me, including, allergies, itchiness, and infections. However, it is important for you to know that I can demonstrate hundreds of different conditions that are caused by a great range of factors, such as genetically transmitted diseases, immune system disorders, and bacterial, viral, and fungal infections. But don’t worry! As you can see, the majority of people live a healthy life despite these risks. The Creator has provided your body with a protective mechanism and has taught you how to take care of yourself. My job here is to indicate the Creator and how He has made me a flawless work of art that demonstrates deep meanings behind its complexity. Rather than continuing to give you a lecture on dermatology, it would be better if you were to live according to God’s consent. If you do so, you will be protected from diseases; even if you do become ill, you will have greater patience and moral strength. You will also be more thankful to God for your health.

Open heart surgery is performed after putting the patient to sleep under a general anesthetic. The chest is then opened by the surgeon, and the heart is temporarily bypassed or deactivated for the duration of surgery (although in some new techniques like beating heart surgery or minimal invasion heart surgery, the operation is possible without deactivation of the heart) During this period the functions of the heart are performed by an artificial lung mechanism called the heart-lung machine (cardiopulmonary bypass machine). Performing surgery on a working heart cases where there is no facility for beating heart surgery would be like trying to repair the engine of a car while it is in motion. This is why it is necessary to temporarily prevent the functions of the heart during the operation, which requires great care and accuracy.

Stopping the heart

During this procedure the patient is connected to the machine, thin pipes called cannulae are inserted into the main veins which lead to the heart, and thus the blood which goes to the heart is directed into the heart-lung pump, fed with oxygen, and then redirected into the body. Preventing the function of the heart is not a very difficult process. When the heart-lung machine is activated and the blood is cooled and redirected into the blood vessels, the body temperature is reduced to below 30°C, and this lowers the heart rate and assists the heart to stop functioning. The actual stopping of the heart is performed by feeding a serum containing a concentrated solution of potassium ions into the coronary artery, which feeds the heart muscle. Potassium ions are normally found in the human body but in a fixed proportion; potassium is an electrolyte which, if increased, causes a defect in the heart’s rhythm and can lead to ceasing of the heart function. Feeding the coronary artery rapidly with a rich potassium solution causes the heart to stop within a few seconds and allows the surgeon to perform the operation on a non-functioning, motionless heart.

The heart should not be stopped from functioning for a long period, even if the heart-lung pump is performing the function of the heart successfully. Under normal conditions the pump cannot perform the whole duty of the actual heart and lungs. When the body temperature is reduced, there is a reduction of functioning in many organs of the body to such an extent that they almost stop working, especially the brain. This means that every organ freezes and if the patient’s pulse were taken within this period, they would be assessed as dead.

Restarting the heart

To restart the heart following the operation a reversal of the procedure performed at the beginning of surgery is necessary; the temperature of the body is increased to 36.5–37°C again with the help of the heart-lung pump, and at the same time the amount of potassium in the blood is reduced to a normal level. This is usually executed by ensuring the normal function of the kidneys which discard the potassium from the body. This is when the function of the heart is monitored closely because there is a reversal in the process of inducing low body temperature and the excess of potassium which caused the heart to stop. In other words, the barrier which stopped the flowing river is removed; therefore, according to the laws of physics, the trapped fluid should flow again at great speed, and although following surgery the majority of hearts do begin to function again when these procedures are performed, there is unfortunately no actual guarantee. There may be certain complications or even causes which we have not yet discovered, in which case an electric shock of 10–20 joules is delivered directly to the heart muscle to encourage it to function normally. If this is unsuccessful, medication such as adrenalin, which induces the functioning of the heart, is given to the patient. If, following these repeated procedures, there is no effect, and, regardless of all the effort, the heart does not function, then everything is performed again from the beginning, including the operation. But there is always the possibility that the desired result may not be achieved. Human beings always face the prospect of death in daily life, and although there is a very slim chance of death, with such a big operation there is always the possibility.

The result

We are normally totally unaware of the rhythmic incidents, a combination of great harmony, occurring within our bodies. Even breathing, a necessity for every living creature to stay alive, is not an action which we activate and continue of our own will. Sight, hearing, hunger and senses are acts of nature over which we have little direct will or power. Nevertheless, they are all events which we can only describe as divine miracles and what a great blessing it is that none of these complex functions of our bodies have been left to us humans.

The sun radiates an enormous amount of energy-at a rate of 3.9×1026 Joule per second. This is roughly equivalent to the energy of a 10 billion megaton TNT bomb every second. This huge amount of energy has been maintained for several billion years and will continue for several more. The fusion reaction of the Sun is a process in which hydrogen burns, transforming into helium, which is then followed by thermonuclear explosions. Isotopes of hydrogen, such as deuterium and tritium, are fused to form heavier helium. During this process the released energy can be as high as 17.6 MeV. The energy released from a 17 lbs deuterium fusion is equal to 1,000 kilotons of TNT. Every second the Sun fuses 675,000,000 tons of hydrogen into 653,000,000 tons of helium.

Scientists have attempted to make fusion work on the earth to make larger amounts of energy, thus solving our energy problems for the future. The first nuclear fusion trials were carried out for nuclear weapons. The released energy from the fusion trials was 500 times higher than that from the fission reactions of nuclear weapons¹. The energy released was equal to that of approximately 12 million tons of TNT. The civilian applications for energy production began in the early 1950s, and we are still trying to solve how to control this amount of energy in reactors.

In nuclear fusion, the negative and positive ions of hydrogen, called plasma, reach temperatures of 100 million degrees. To achieve the plasma parameters of the Sun, for example, the same temperature and density, the plasma must be heated to 100 million degrees Celsius and be kept dense and confined for at least 1 second.

Plasmas are mostly heated by Ohmic (resistive) heating, beam injection, or radio frequency heating. Ohmic heating is the result of an induced current being passed through the plasmas. This mechanism is also used to make electric bulbs and heaters work. Ohmic heating cannot attain plasma temperatures; such heating does not rise above 20-30 million degrees Celsius. When the temperature increases, the resistivity of the plasma decreases. Natural beam injection is one of the mechanisms used to obtain higher energy temperatures. Injecting a high-energy beam of neutral atoms into the plasma causes more collisions and increases the plasma temperature by transferring the atoms’ energy to the plasma. Radio frequency heating is another collision mechanism that increases the plasma temperature. Radio waves generated by oscillators transfer their energy at appropriate frequencies to ions or electrons, thus increasing the plasma temperature. Scientists have managed to get to high enough temperatures; however, these plasmas cannot be contained by the reactor walls easily and the reactions cannot be sustained. To prevent a loss of reaction control and to make the plasmas denser, magnetic confinement mechanisms have been developed such as TOKAMAK, Z-PINCH and ICF.

The TOKAMAK (Toroidal Chamber) device was invented in the late 1950s by the Russian physicists Igor Tam and Andrei Sakharov. In this system, mixtures of deuterium and tritium plasmas, confined by doughnut-shaped magnetic fields, are produced by the toroidal coils, which are then heated to very high temperatures. The temperature achieved by the Princeton Labs is 510 million degrees-almost 30 times greater than the temperature of the Sun. One of the major problems in TOKAMAK is that superconducting magnetic coils are needed for the electricity demand, but the superconducting magnets only operate at cold temperatures. So, a space between the plasma and coils must be maintained to avoid the plasma reaching the coils and damaging them. This mechanism is still assumed to be the best for the confinement of plasmas².

Another confinement system is the Z-pinch (Zeta-Pinch) pulse power device. The current flow of experimental devices is in the Z-axis, so the device was called the Z-pinch by the British scientists in the late 1950s. In this mechanism, very tiny wires, thinner than a human hair, are positioned in different configurations, such as cylindrical or nested geometries, and are then placed in an anode cathode gap.

Applying high voltage on the system causes the energetic plasmas to compress and heat the deuterium or tritium fuel in small pellets. The current flows through these wires axially, generating magnetic fields that confine the plasma. The temperature achieved is about 1.6 billion degrees; this result, reported by the Sandia National Labs, is almost 250 times higher than the interior of the Sun. Z-pinches produce the most powerful plasmas, but the generated plasmas are very unstable³.

Lasers were invented in 1962, and have been applied in many areas. Lasers were used in infusion research to confine the plasma in the late 1960s by scientists at Lawrence Livermore. This laser-based process is called ICF (Inertial Confinement Fusion). In this mechanism, laser light is used to compress and heat the pellet. The temperature achieved is about 100 million degrees Celsius and the plasma is compressed almost 1,000 times its liquid density. However, this confinement occurs in less than in a microsecond, which is not enough time to allow the ions to build on the energy of their own inertia.

Today, many countries have invested millions of dollars in confinement and ignition systems to create fusion power. ITER is an International TOKAMAK fusion project that will be built in France (for more information: http://www.iter.org/). Its participants have agreed to provide funding of $13.1 billion. When it is completed, the ITER will be one of the most expensive scientific projects in the world. However, despite the high cost, there are good reasons why scientists insist on the use of fusion. One of these is that no CO2 is produced during the process. Everyone is aware that CO2 has negative effects; for example, it leads to increased pollution and global warming. Another reason is the abundance of hydrogen available for fusion in seawater and on the earth’s crust. Another important reason is that fusion is safer than fission or other energy sources: There are no nuclear accidents, and in case of malfunction, the plasma is absorbed and cooled by the reactor walls. Also, the generated amount of radioactive particles is fewer than those generated by fission.

If everything goes well, scientists expect that fusion will be used as a source of energy in a couple of decades. If fusion is successful, it can provide clean, safe, reliable, sustainable, and widely applicable energy.

M. Fatih Yilmaz is a graduate researcher at Physics Department, University of Nevada.

Notes

1. Frisch O. R.: “The Discovery of Fission – How It All Began.” Physics Today 20 (1967), 11, pp. 43-48; http://en.wikipedia.org/wiki/Nuclear_fission.

2. http://en.wikipedia.org/wiki/Tokamak; http://www.ppdl.gov.

3. James Glanz, Science 18 July 1997:Vol. 277. no. 5324, p. 306 DOI: 10.1126/science.277.5324.306.