What possible similarities could there exist between a human and a tree? Interestingly, the open wounds of human beings and trees are subject to the same laws and are healed in similar ways.

Have you ever wondered what kinds of similarities exist between human skin and the bark of a tree?

Trees are subject to major and minor injuries just like humans are. These injuries could be the result of a broken branch, insect infestation, animal damage, fire and human related damages. These kinds of injuries can lead to the infection of a plant which can cause rotting and damage to the transport tissues like phloem (nutrients) and xylem (water) by microorganisms and insects (bacteria, fungi, parasites).

Fluid excretion in wounds and development of scar tissue

Blood serum is secreted in human wounds, whereas gum and resin type fluids are secreted in various trees (Figure 2 and 3). Serum plays an important role in sterilization of the wound, along with blood coagulation. Defense mechanisms in trees involve excretion of different fluids (resin in needle-leaf trees, gum in broadleaf trees) that are synthesized via composition of various chemicals. The most important feature of these fluids is that with their special chemical make up, they can protect the wound from organisms like bacteria, fungi, and insects that are potentially harmful to the tree. These fluids also feature coagulation like the human serum; they congeal and solidify after excretion and trigger a biological healing process while physically covering the wounded area.

Wounds are repaired with new connective tissue cells (fibroblasts) in humans and by callus in trees. Healing of the wound following the coagulation takes place with proliferation of cells in this region (epithelialization). First, epithelial cells wrap the wound via proliferation. New transport tissue is developed during this process. Next, fibroblasts that are in charge of wound repair are transferred into coagulate via this transport tissue. Fibroblasts synthesize collagen protein of the required fiber structure needed for the wound repair. Injured area is woven with these, and recovers its former shape in time depending on the size of the wound.

Healing is granted through timely reproduction, transformation and maturation of paranchimatic cells that make up the callus, when only a portion of tree bark is damaged. Paranchimatic cells are fused side by side and they form a thick elevation of callus tissue around the wound (Figure 4). At the end, these are activated for the development of a new, healthy cambium and bark. Cambium tissue is responsible for vertical and lateral growth of a tree therefore it is vitally important that it does not suffer any damage. This tissue in growth season proceeds from the perimeter of the wound towards the center for a complete healing. The productive efficiency of the tree medium can speed up or slow down the curing process similar to humans.

The reality is that all living things are created with a dress suited for their environments so that their bodies can be protected from negative elements from the outside world. Organisms are armored from many harmful physical (mechanical, extreme temperatures, light etc.) and chemical effects with this perfectly bestowed dress as a manifestation of the divine compassion in the universe just as in the case of the wounds of humans, animals and plants which are subject to the similar laws found in nature.

They are tiny, and there are billions of them inside you. Tiny machines, one thousand times thinner than a hair strand but strong enough to carry all kinds of material within your cells. Yes, there is a complex army of tiny machines inside your body performing an amazing array of functions while you sit at home sipping your tea.

Your heart is beating. Its lifelong duty is to pump blood to tissues to deliver essential nutrients. Transportation of nutrients continues from blood vessels to cells and then into subcellular compartments. Inside of a cell, there is a need for sophisticated biomachines which are responsible for transport. Did you know that you were equipped with minuscule motors that transported cargos in your cells? Or about cellular highways where molecular cargos are transported?

There are various proteins called “motors” in the cell. They can convert chemical energy to mechanical energy to produce force and motion in the cellular highways.¹ Amazingly, molecular motors are much superior to man-made motors in terms of energetic efficiency by hydrolyzing ATP to fuel enzymatic reactions. These molecular motors include rotary motors, polymerization motors, nucleic acid motors and cytoskeletal motors.

Rotary motors

Bacterial flagellum, used for swimming, acts as a propeller and uses a rotary motor. It has been suggested that this motor is similar to Fo motor found in FoF1-ATP synthase. FoF1-ATP synthase takes part in the conversion of chemical energy in ATP to proton gradient, or vice versa. This chemical reaction involves mechanical rotation of parts of the complex.

Polymerization and nucleic acid motors

Polymerization motors take role in polymerizations and these polymerizations generate forces for repulsion (Actin or microtubule polymerization), or separation of clathrin buds from plasma membrane (Dynamin).

DNA and RNA synthesis also involves the use of molecular motors such as RNA polymerase (RNA synthesis from DNA), DNA polymerase (DNA synthesis), Helicases (separation of double stranded DNA prior to DNA or RNA synthesis), Topoisomerases (removal of supercoiling of DNA), RSC, SWI/SNF, and SMC proteins (Chromatin remodeling and chromosome condensation). Moreover, there are specific viral DNA packaging motors that pack tightly viral DNA into capsids. separation of double stranded DNA prior to DNA or RNA synthesis), Topoisomerases (removal of supercoiling of DNA), RSC, SWI/SNF, and SMC proteins (Chromatin remodeling and chromosome condensation). Moreover, there are specific viral DNA packaging motors that pack tightly viral DNA into capsids.

Cytoskeletal motors

Dyneins, kinesins and myosins denote the three major classes of molecular motor that moves along cytoskeletal structures. Myosin is among the most prominent of motor proteins that takes role in muscle contraction. Kinesin operates on microtubules (long tubes composed of dimers of the protein tubulin, arranged to form 13 parallel tracks) to move cargos inside the cells away from the nucleus (toward positive end of microtubules) and play essential roles in the formation of spindle apparatus and axonal transport. Dynein is also known to transport cargo but in the opposite direction to Kinesin, towards the cell nucleus (toward minus end of microtubules). In addition, dynein is required to beat cilia and flagella.

How molecular motors move

Myosin and kinesin are structurally similar in terms of being dimeric with two motor heads, two legs, and a common stalk. The head regions control the forward movement by binding itself to actin or microtubule filaments. Movement is facilitated by the consumption of ATP by ATPase sites. It is fascinating how these motors translate chemical energy into motion and still be different to the movement of cars. There are different proposals as to how molecular motors move, such as walking (hand-over-hand model), inchworm model, and biased diffusion model.

The-hand-over-hand model suggests that ATP binding induces a conformational change in the forward head movements and keeps fixed, thus leading to the movement of the rear head forward and vice versa. This model, which is also known as the walking model, is similar to upright walking where one foot moves forward while other stay fixed, and vice versa. On the other hand, the inchworm model suggests that only forward head movements use ATP and leads while the other head follows. Studies on the Myosin VI with shorter legs suggested a biased diffusion model. In the diffusion model, the motor moves randomly to the next binding site in a forward direction. In order to find out which mechanism used by molecular motors, scientists measured how much of the head moves following staining with a fluorescent dye. Since molecular motor movements are so small (5-10 nM), optical traps and cantilever probes (>100 μm) were not useful to watch head movements. By increasing both photostability and brightness of organic dyes, Dr. Yildiz at UC Berkeley was able to measure head movements down to 1.5nM scale.

Kinesin: A molecular motor that walks

Kinesins are among microtubule-based motors recently shown to walk like a mountain climber by swapping its two motor units (analogous to feet) in a hand-over-hand mechanism rather than an inchworm mechanism. This recent discovery sheds light on how kinesin moves its cargos such as membrane components, messenger RNA, signaling moleculers, and others along microtubules. In addition, as suggested by findings of Dr. Yildiz, kinesin demonstrates an asymmetric walking where motor heads alternate with slow and fast steps. Further studies using advanced microscopy techniques (called FIONA) which allow nano scale detection of movement down to 2nM resolution demonstrated delicately that processive kinesin motor takes about 8 nM steps (eight-billionths of a meter) for each ATP molecule consumption with alternating 16-nm and 0-nm steps. Furthermore, kinesin is attached to the microtubule while it waits for ATP between steps. Since kinesin is used for long distance cargo transport on relatively big highways of a cell, it elegantly demonstrates a processive motor that reliably travels in a coordinated manner. Of course, not all motors will be moving like kinesin.

Dynein moves through uncoordinated stepping of ring domains

Another motor protein involved in long distance cargo transport is dynein. Dynein is a staggering giant which is much bigger and complex than kinesin and myosin motors. There are about 15 types of dyneins known to take role in cilia and flagella movement and 2 cytoplasmic forms. Cytoplasmic dynein is a homodimeric AAA+ (ATPases associated with cellular activities) motor that transports toward the microtubule minus end, acting opposite to kinesin. FIONA assay demonstrated that the heads moving processively but independently. This mechanism is quite different from the hand-over-hand stepping of kinesin and myosin, for dynein’s steps are not strictly coordinated and highly variable. Most of the time, dynein heads move alternatively with variable head-to-head distance of about 5-50nM. Each head of dynein mostly does not pass each other.

Elegant design, efficiency in transportation and being part of the living system makes molecular motors in the cells superior to man-made motors. Molecular motors travel on cellular highways in the cellular microcosm in the manner of dutiful officials of a king traveling in his domain in security via the fastest modes of transportation and easily cross provincial boundaries, demonstrating more evidently that the Sovereignty of the Eternal King is limitless. Indeed, the signs of His Dominion are reflected by each and every entity from the microcosmic world to macrocosmic universe.

Note

1 Cellular highways are composed of microtubules, microfilaments and actin filaments. Myosin moves along microfilaments through interaction with actin, but dynein and kinesin move along microtubules through interaction with tubulin

References

• DeWitt MA et al. Cytoplasmic dynein moves through uncoordinated stepping of the AAA+ ring domains. Science. 2012 Jan 13;335(6065):221-5. Epub 2011 Dec 8.
• King SM. AAA domains and organization of the dynein motor unit. J Cell Sci. 2000 Jul;113 ( Pt 14):2521-6.
• Wilhelm J. Walter & Stefan Diez. A staggering giant. Nature. Vol 482. 2 February 2012.
• Molecular motors and Motor proteins. Retrieved from Wikipedia on 3/31/2012.
• Yildiz et al. Myosin V Walks Hand-Over-Hand: Single Fluorophore Imaging with 1.5-nm Localization. Science 27 June 2003:Vol. 300 no. 5628 pp. 2061-2065
• Yildiz et al. Kinesin Walks Hand-Over-Hand. Science 30 January 2004: Vol. 303 no. 5658 pp. 676-678

Driver Information

The most recent applications sought to complement the driver’s ability by targeting such “hands-off, feet-off” driving systems (Fig. 1) as PATH (Partners for Advanced Transit and Highways) and PROMETHEUS (Program for European Traffic with Highest Efficiency and Unprecedented Safety).

For transportation, IT generally can be classified into four groups: Driver Information and Route Guidance, Traffic Flow and Parking Control, Public Transport and Fleet Management, and Automatic Debiting. Only the first item will be discussed in this article.

Driver Information and Route Guidance

Driver Information (DI) and Route Guidance (RG) systems help drivers navigate unfamiliar roads or find the quickest route. The information, especially that given by more advanced systems, consists of advice that drivers can accept or ignore, or a directive with which they are expected to comply. DI and RG can help them reduce or curtail poor route choice as well as excess distance and travel times. The most likely information requested is shortest recommended path, state of the road and weather conditions, unexpected incidents ahead, and the general traffic situation (to estimate travel time).

Disseminating Information

Roadside displays, consisting of fixed road signs and variable message signs, are the simplest DI systems (Fig. 2). The relevant technology is quite basic, as the goal is to give all drivers general information about existing roadway conditions. Variable message signs are used mainly on highways. In urban areas, they are particularly well-suited for providing information about roadway conditions and parking lot availability.

The second method, cellular-radio networks such as the Radio Data System-Traffic Message Channel (RDS-TMC) proposed by the European Broadcasting Union, enable digital information to be superimposed on normal VHF/FM broadcasts. Information can be filtered (drivers call up only what they need and when they need it), updated any time, and broadcast in different languages.

Also, there is no need to lay cables, as is the case with beacon-based RG techniques.

The third (and most sophisticated) method is the electronic RG system, which consists of in-vehicle units, roadside equipment, and control centers (Fig. 3 ). It is usually difficult to start installing the ground infrastructure before ensuring the wide use of onboard systems. Onboard equipment for dynamic navigation comprises a transceiver, a router with a display, a locator with sensors, dead-reckoning devices, and a map memory. The usual indicators of route selection criterion are shorter distance, minimum cost, less traffic, fewer stops, and greater safety. The result of route optimization is the recommendation of how to reach a destination from a given starting point. This can be done by calculating the optimum route for an origin-destination, and by determining the turning directions from the vehicle’s route and position.

Some Examples in Use

CARIN (CAR Information and Navigation System) is an autonomous (static) navigation system used in route planning and guidance. A simplified digital map, stored on a CD, shows the best route. It also offers verbal guidance via a speech synthesizer and gives general tourist information. Other in-vehicle equipment consists of a sensor (magnetic compass) and a navigation computer that carries out the main task. Data collection, in terms of positioning and directing, is implemented by the moving vehicle’s sensors. This information, updated every 3 seconds, is used for map-matching.

The system’s basic advantage is that it does not rely on any external sources, like expensive beacon infrastructures. The route planner algorithm determines the best route for minimizing travel time and distance. However, as CARIN cannot receive current network and traffic situation reports, it is being modernized so that it can receive external information via the car radio with the introduction of RDS-TMC. Moreover, in the future CARIN will offer a fully interactive traffic management opportunity using the European D-net telephone system.

TrafficMaster was one of the first in-vehicle information systems introduced. It was applied first to the M25 London orbital highway, and then to the whole UK highway network. Data is obtained through sensors installed on highway bridges. In case of congestion, messages (such as locations and types of traffic jams and average traffic speed) are generated and transmitted by the control center. The in-vehicle unit displays the current status of the roadway network covered by the sensors. This dissemination is performed minute-by-minute. enabling the driver to make convenient route choices.

In Euro-Scout, the driver enters a destination into a small in-vehicle computer. As the vehicle moves, the in-vehicle navigation equipment determines its position. Whenever it passes a beacon, the user receives the best route, generated by the central computer, for all destinations.

Communication is performed through a two-way infrared link. Beacons located next to the signal heads can use existing cables when they are mounted with traffic lights. Guided vehicles can measure link travel times, which are then returned to the central computer via the beacons in a so-called vehicle telegram. This information is updated continually by the center. The system, therefore, is characterized by its centralized feature: The main data process is carried out in the control office rather than in-vehicle units.

The system has been introduced in Stuttgart by installing 130 beacon heads on traffic lights. A second system of 340 beacons is located in Berlin, and a third one is in Oakland county, Michigan, with 100 beacons and 1,000 equipped vehicles. Start-up costs are high, but in-vehicle equipment costs and the cost of increasing users are low.

In comparison, SOCRATES’ start-up costs are much lower, while the costs of equipping each vehicle and adding additional users are high. This system does have some weak points, though:

The routing algorithm does not take multi-destination users into account, the system is heavily dependent of roadside infrastructure, and a breakdown in the center may cause a system-wide failure.

SOCRATES (System Of Cellular RAdio for Traffic Efficiency and Safety), a two-way communication system, is based on the Global System for Mobile Communications (GSM) cellular radio network. SOCRATES measures the travel times of all guided vehicles from point to point, and uses this information to determine the best routes. In-vehicle units, an odometer, a compass for dead reckoning, and a map pass information to and from roadside units, which are connected to the central computer over telephone lines that allow medium-range communication.

The downlink from the base station to the vehicle is operated in a broadcast mode for disseminating traffic information. The uplink to the base station allows multiple access by floating cars in order to collect travel time patterns. The system’s main disadvantage is the cost of using the mobile phone network. However, a significant benefit is that using the cellular radio requires no additional infrastructure investment because of the introduction of GSM.

The Need for Such Systems

Transport enables socioeconomic relationships to be developed and sustained. This is clear in the continuous dependence on various means of transport to move goods and people. Neglecting transport would bring society to standstill, literally and metaphorically. The introduction of the car put personal transport on the top and increased the need for more roads. The greater the demand for individual mobility, and hence roads, the more complex road transport problems become.

The number of cars per mile of road grows daily. At the same time, lack of space, budgetary priorities, and environmental considerations restrict the extent to which new road construction and increased capacity can be undertaken. But people still want to travel as smoothly as possible.

Therefore, the central idea is that traffic information and communication systems will offer effective solutions-especially where physical changes to the existing infrastructure, such as constructing new links or widening roads, are almost impossible. Closer following distances between intelligent vehicles on automated highways will eventually increase road network capacity.

The Advantages of RG Systems

The main appeal of dynamic RC systems is their ability to recommend paths based on current traffic conditions. Recent research and systems development have focused mainly on dynamic RC systems, which are superior to static systems. Dynamic RC is particularly well-suited for tackling urban congestion, and has advantages over other technological measures, such as vehicle-actuated traffic signals or a system of dynamically updated VMS.

Drivers normally reach their destination by following a route based on previous experience, maps, street signs, and radio traffic bulletins. However, studies show that drivers are unable to select the shortest route, leading to some 6 to 8 percent errors. Preventing this by even static RG could save millions of dollars per year. Driver misperceptions, due to the absence or scanty amount of information about travel time and alternative routes, as well as about specific route incidents, lead to delay and wasted mileage. In Orlando, tourists driving RC-equipped vehicles made 30 percent fewer wrong turns and shortened their travel times by 20 percent, compared to drivers who used paper maps.

Research indicates that applying dynamic RG systems shows great potential for improving travel times, safety, and environmental effects. This is based on the assumption that more drivers will opt to use the services. Other benefits could include satisfaction derived from choosing the best route and being better informed, reduction in the total distance travelled, and incident detection and warning. The real benefit will depend largely on the quality of information provided. With more computing power becoming available and increased technological advancement, more high-quality information is available to drivers.

RG not only guides vehicles through unfamiliar areas, but also increases roadway safety. For example, research indicates that 60 percent of crashes at intersections, and about 30 percent of head-on collisions, could be avoided if drivers had an additional half-second to react. Systems like automatic collision notification (not readily available yet) immediately signal for help if a vehicle’s airbag deploys. In addition, drowsy-driver warning systems keep drivers from falling asleep at the wheel.

The Shape of Things To Come

The discussion so far has focused on the present state of intelligent transport systems. In-vehicle information systems provide information on road conditions and offer advice. They also can provide information about a city’s hotels, catering, theater, cinemas, and even the entire yellow pages. In-vehicle systems can function as hand-held car locators, whether in a busy parking lot or in the remote countryside.

The future of such systems already is taking shape. Dual-purpose and hand-held in-vehicle systems can be used as personal security guards that send a discrete message to a control center when a user is in danger. They could sound an alarm to scare off potential attackers and draw attention to oneself. They also could be built into a car’s security system to prevent theft and send messages in case of an accident.

Hands-free cars are being developed to navigate the road network by the use of a button relying on in-built computers. In addition, car prototypes are being developed that do not require roads-they will fly from origin to destination. All of these require intelligent navigation through a combination of computing and communication. The merging of computing and communication is the bedrock of a revolution to unify all technologies. Journeying intelligently will be at the forefront of this revolution.

Conclusion

Applying these systems, both vehicle- or network-based, depend heavily on the society’s living standards and the country’s economic level of development. Variable message signs and TMCs are the most convenient systems for developing countries, due to their simplicity and cheapness. A typical variable message sign only costs about $200,000, while more sophisticated systems requiring computer centers, roadside equipment like beacons and in-vehicle units, are more expensive. However, in cities with high traffic levels, authorities may consider establishing electronic navigation and information systems with the cooperation of private investors and vehicle manufacturers.

People tomorrow will be more mobile than ever. To provide better transportation systems for the twenty-first century requires the integration of people, vehicles, and network, as well as the improved safety and efficiency of transport systems. Therefore, dynamic DI systems should be able to offer improved mobility for travelers, reduced travel times and operation costs, reduced transportation infrastructure costs, improved highway safety, and reduced transportation energy consumption, transport-generated pollution, and noise.

References

• Barco Visual Systems. Traffic Technology International ‘98 (Feb/ March 1998): 18.
• Benz, D. “PROMETHEUS.” High Tech Report (April 1994).
• Catling, I. “SOCRATES.” Advanced Technology for Road Transport: IVHS and ATT. Ed. I. Catling. Boston: Artech House, 1994, 65-78.
• Georg, L. and F. Steinkohl. “Driver Assistance Concepts and Systems.” Traffic Technology International ‘98 (Oct-Nov. 1997): 66
• Hypower Inc. Traffic Technology International December ‘97 – January ‘98 (1997): 10.
• Intellimotion. Research Updates in Intelligent Transportation Systems. 6(4), (1997): 1.
• Jeffery, D. “Route Guidance and In-Vehicle Information Systems.” Information Technology Applications in Transport. Eds. P. Bonsall and M. C. H. Bell. Utrecht, The Netherlands, 1986, 319-51.
• Kontron Elektronik. Traffic Technology International ‘98 (Annual Review 1998): 232.
• Little, C. “The Intelligent Vehicle Initiative.” Public Roads (Sept.- Oct. 1997): 18-25.
• Siemens. The Power of Integration; Traffic Management; Driver Information. France: Siemens Automotive S.A., 1994.