Biography of a Race Essay Example for Free

Biography of a Race Essay It may be hard for biographers to win prize for his work. Therefore, for this to happen, it would take an exceptional skill paired with devoted attitude towards the craft. Such award as Pulitzer Prize requires these and David Levering Lewis apparently has these as proven in his biography about the civil rights leader William Edward Burghart Du Bois. The book is called ‘Biography of a Race’ which shows a remarkable manner of tackling of the life of Du Bois. It shows with clarity the picture of the environment in which the struggles set for the purpose of an endeavor. The complexity of this civil right leader’s involvement in socio political movements was carefully drawn with a structure that is outlined according to significant key points. The life of Du Bois revolves around his contribution with the condition of the present American society. He tried to escape the stereotypical position of blacks as subject class. Du Bois strived to gain social reform and have equity among the people regardless of race and color. He pushed the belief that blacks should also have access on all essential community benefits such as education. His life story is indeed challenging for any biographer to write. The whole context of the book is particularly exquisite although there are some parts of the first five of eleven chapters that may seem a little bit confusing. The length of the passages may require some reader to go over it again to get the key points but otherwise, they are precise. It is given that the life of Du Bois is complex and that can be the reason for this. The choice of the right approach is the true mark of Lewis’s skill in telling story and history. His book is a comprehensive study of a life story and succeeded in its purpose to reflect the life that made a huge contribution in the history. Thus, an award is nothing but deserved. Reference Lewis, D. L. (1993). W. E. B. Du Bois, 1868-1919: Biography of a Race. ON: Henry Holt and Company, LLC

How much sympathy do you have for the woman in Tony Kytes arch :: English Literature

How much sympathy do you have for the woman in Tony Kytes arch deceiver’ and Tickets please ? In this essay I am going to argue about how much sympathy I have for woman in the 2 stories that I have studied. The two stories I have studied are ‘Tony Kytes arch-deceiver’ and ‘Tickets please’. "Tony Kytes: arch deceiver" was set at the end of the nineteenth century in a rural community which seems unaffected by the Industrial Revolution, remaining traditional in both the way of life and the attitudes of the people. The members of the community are very relaxed in the way that they live, riding around in the carts, being very leisurely, especially the women who did hardly any work other than in the house. "Tickets Please", set 25 years later, has a much more urban setting with a tougher, faster lifestyle, with all the danger and excitement of the tramlines shown in the assertive and self-assured behaviour of the women who work on them. The men were away at war and the women were doing jobs which had previously been thought suitable only for men. They had been given freedom and were empowered and able to take liberties giving them confidence and making them examine their own lives and ambitions. They were beginning to believe that they were equal in status to men, and therefore were no longer acting in such a traditional, gentle, delicate and soft manner. Both stories tell us, that men at this time like to be able to have the prettiest girl, and enjoy being able to choose from several. In "Tony Kytes" it appears very important for the women to be good looking, as they are all mentioned in terms of their looks, being described as "dashing" or "handsome". The women are aware that looks are important and even think that this alone will enable them to find a husband. Tony Kytes the Arch Deceiver" is a funny story of an afternoon when Tony was driving home from the market in his wagon. A pretty girl called Unity to who he was quite close before he met his present fiancà © stopped him and asked him to give her a lift home. They were riding along, having a flirtatious conversation, when Tony saw Milly, his fiancà ©. Fearing her displeasure on seeing Unity riding with him on the wagon, he manages to persuade Unity to hide at the back of the wagon. ‘avoid all unpleasantness, which I know ye can't bear any more than I, will ye lie down in the back part of the wagon, and let me

Optical Computing Essay

Jainam Shah Kalol Institute Of Technology, Kalol, Gujarat, India. jainam_8888@yahoo.co.in Abstract—Optics has been used in computing for a number of years but the main emphasis has been and continues to be to link portions of computers, for communications, or more intrinsically in devices that have some optical application or component (optical pattern recognition, etc). Optical digital computers are still some years away, however a number of devices that can ultimately lead to real optical computers have already been manufactured, including optical logic gates, optical switches, optical interconnections, and optical memory. The most likely near-term optical computer will really be a hybrid composed of traditional architectural design along with some portions that can perform some functional operations in optical mode. Computing applications as a consequence of faster processing speed, as well as better connectivity and higher bandwidth. II. NEED FOR OPTICAL COMPUTING The pressing need for optical technology stems from the fact that today’s computers are limited by the time response of electronic circuits. A solid transmission medium limits both the speed and volume of signals, as well as building up heat that damages components. One of the theoretical limits on how fast a computer can function is given by Einstein’s principle that signal cannot propagate faster than speed of light. So to make computers faster, their components must be smaller and there by decrease the distance between them. This has resulted in the development of very large scale integration (VLSI) technology, with smaller device dimensions and greater complexity. The smallest dimensions of VLSI nowadays are about 0.08mm. Despite the incredible progress in the development and refinement of the basic technologies over the past decade, there is growing concern that these technologies may not be capable of solving the computing problems of even the current millennium. The speed of computers was achieved by miniaturizing electronic components to a very small micron-size scale, but they are limited not only by the speed of electrons in matter but also by the increasing density of interconnections necessary to link the electronic gates on microchips. The optical computer comes as a solution of miniaturization problem. Optical data processing can perform several operations in parallel much faster and easier than electrons. This parallelism helps in staggering computational power. For example a calculation that takes a conventional electronic computer more than 11 years to complete could be performed by an optical computer in a single hour. Any way we can realize that in an optical computer, electrons are rep laced by photons, the subatomic bits of electromagnetic radiation that make up light. I. INTRODUCTION With the growth of computing technology the need of high performance computers (HPC) has significantly increased. Optics has been used in computing for a number of years but the main emphasis has been and continues to be to link portions of computers, for communications, or more intrinsically in devices that have some optical application or component (optical pattern recognition etc.) Optical computing was a hot research area in 1980’s.But the work tapered off due to materials limitations that prevented opt chips from getting small enough and cheap enough beyond laboratory curiosities. Now, optical computers are back with advances in self-assembled conducting organic polymers that promise super-tiny of all optical chips. Optical computing technology is, in general, developing in two directions. One approach is to build computers that have the same architecture as present day computers but using optics that is Electro optical hybrids. Another approach is to generate a completely new kind of computer, which can perform all functional operations in optical mode. In recent years, a number of devices that can ultimately lead us to real optical computers have already been manufactured. These include optical logic gates, optical switches, optical interconnections and optical memory. Current trends in optical computing emphasize communications, for example the use of free space optical interconnects as a potential solution to remove ‘Bottlenecks’ experienced in electronic architectures. Optical technology is one of the most promising, and may eventually lead to new III. SOME KEY OPTICAL COMPONENTS FOR COMPUTING The major breakthroughs on optical computing have been centered on the development of micro-optic devices for data input. A. VCSEL (Vertical Cavity Surface Emitting Laser) VCSEL (pronounced ‘vixel’) is a semiconductor vertical cavity surface emitting laser diode that emits light in a cylindrical beam vertically from the surface of a fabricated wafer, and offers significant advantages when compared to the edge-emitting lasers currently used in the majority of fiber optic communications devices. The principle involved in the operation of a VCSEL is very similar to those of regular lasers. Fig. 2. Optical Interconnection Of Circuit Boards Using Vcsel And Photodiode VCSEL convert the electrical signal to optical signal when the light beams are passed through a pair of lenses and micromirrors. Micromirrors are used to direct the light beams and this light rays is passed through a polymer waveguide which serves as the path for transmitting data instead of copper wires in electronic computers. Then these optical beams are again passed through a pair of lenses and sent to a photodiode. This photodiode convert the optical signal back to the electrical signal. B. SLM (Spatial Light Modulators) SLM play an important role in several technical areas where the control of light on a pixel-by-pixel basis is a key element, such as optical processing and displays. 1) SLM For Display Purposes Fig. 1. Two semiconductor materials sandwiching an active layer There are two special semiconductor materials sandwiching an active layer where all the action takes place. But rather than reflective ends, in a VCSEL there are several layers of partially reflective mirrors above and below the active layer. Layers of semiconductors with differing compositions create these mirrors, and each mirror reflects a narrow range of wavelengths back in to the cavity in order to cause light emission at just one wavelength. For display purposes the desire is to have as many pixels as possible in as small and cheap a device as possible. For such purposes designing silicon chips for use as spatial light modulators has been effective. The basic idea is to have a set of memory cells laid out on a regular grid. These cells are electrically connected to metal mirrors, such that the voltage on the mirror depends on the value stored in the memory cell. A layer of optically active liquid crystal is sandwiched between this array of mirrors and a piece of glass with a conductive coating. The voltage between individual mirrors and the front electrode affects the optical activity of liquid crystal in that neighborhood. Hence by being able to individually program the memory locations one can set up a pattern of optical activity in the liquid crystal layer. C. Smart Pixel Technology Smart pixel technology is a relatively new approach to integrating electronic circuitry and optoelectronic devices in a common framework. The purpose is to leverage the advantages of each individual technology and provide improved performance for specific applications. Here, the electronic circuitry provides complex functionality and programmability while the optoelectronic devices provide high-speed switching and compatibility with existing optical media. Arrays of these smart pixels leverage the parallelism of optics for interconnections as well as computation. A smart pixel device, a light emitting diode under the control of a field effect transistor can now be made entirely out of organic materials on the same substrate for the first time. In general, the benefit of organic over conventional semiconductor electronics is that they should lead to cheaper, lighter, circuitry that can be printed rather than etched. D. WDM (Wavelength Division Multiplexing) Wavelength division multipl exing is a method of sending many different wavelengths down the same optical fiber. Using this technology, modern networks in which individual lasers can transmit at 10 gigabits per second through the same fiber at the same time. which interact with light and modulate its properties. Several of the optical components require efficient-nonlinear materials for their operations. What in fact restrains the widespread use of all optical devices is the in efficiency of currently available nonlinear materials, which require large amount of energy for responding or switching. Organic materials have many features that make them desirable for use in optical devices such as 1) High nonlinearities 2) Flexibility of molecular design 3) Damage resistance to optical radiations Some organic materials belonging to the classes of phthalocyanines and polydiacetylenes are promising for optical thin films and wave guides. These compounds exhibit strong electronic transitions in the visible region and have high chemical and thermal stability up to 400 degree Celsius. Polydiacetylenes are among the most widely investigated class of polymers for nonlinear optical applications. Their subpicosecond time response to laser signals makes them candidates for high-speed optoelectronics and information processing. To make thin polymer film for electro-optic applications, NASA scientists dissolve a monomer (the building block of a polymer) in an organic solvent. This solution is then put into a growth cell with a quartz window, shining a laser through the quartz can cause the polymer to deposit in specific pattern. V. ADVANCES IN PHOTONIC SWITCHES Logic gates are the building blocks of any digital system. An optical logic gate is a switch that controls one light beam by another; it is ON when the device transmits light and it is OFF when it blocks the light. Fig. 3. a. Wave length division multiplexing b. A WDM System WDM can transmit up to 32 wavelengths through a single fiber, but cannot meet the bandwidth requirements of the present day communication systems. So nowadays DWDM (Dense wavelength division multiplexing) is used. This can transmit up to 1000 wavelengths through a single fiber. That is by using this we can improve the bandwidth efficiency. IV. ROLE OF NLO IN OPTICAL COMPUTING The role of nonlinear materials in optical computing has become extremely significant. Non-linear materials are those, Fig. 4. Optical AND-logic gate To demonstrate the AND gate in the phthalocyanine film, two focused collinear laser beams are wave guided through a thin film of phthalocyanine. Nanosecond green pulsed Nd:YAG laser was used together with a red continuous wave (cw) He-Ne beam. At the output a narrow band filter was set to block the green beam and allow only the He-Ne beam. Then the transmitted beam was detected on an oscilloscope. It was found that the transmitted He-Ne cw beam was pulsating with a nanosecond duration and in synchronous with the input Nd:YAG nanosecond pulse. This demonstrated the characteristic table of an AND logic gate. A. Optical and Gate In an optical NAND gate the phthalocyanine film is replaced by a hollow fiber filled with polydiacetylene. Nd:YAG green picoseconds laser pulse was sent collinearly with red cw He-Ne laser onto one end of the fiber. At the other end of the fiber a lens was focusing the output on to the narrow slit of a monochromatic with its grating set for the red He-Ne laser. When both He-Ne laser and Nd:YAG laser are present there will be no output at the oscilloscope. If either one or none of the laser beams are present we get the output at the oscilloscope showing NAND function. faster read-out rates. This research is expected to lead to compact, high capacity, rapid-and random-access, and low power and low cost data storage devices necessary for future intelligent spacecraft. The SLMs are used in optical data storage applications. These devices are used to write data into the optical storage medium at high speed. Fig. 6. Optical Disk More conventional approaches to holographic storage use ion doped lithium niobate crystals to store pages of data. For audio recordings ,a 150MBminidisk with a 2.5- in diameter has been developed that uses special compression to shrink a standard CD’s640-MB storage capacity onto the smaller polymer substrate. It is rewritable and uses magnetic field modulation on optical material. The mini disc uses one of the two methods to write information on to an optical disk. With the mini disk a magnetic field placed behind the optical disk is modulated while the intensity of the writing laser is held constant. By switching the polarity of the magnetic field while the laser creates a state of flux in the optical material digital data can be recorded on a single layer. As with all optical storage media a read laser retrieves the data. A. Working The 780nm light emitted from AlGaAs/GaAs laser diodes is collimated by a lens and focused to a diameter of about 1micrometer on the disk. If the re is no pit where the light is incident, it is reflected at the Al mirror of the disk and returns to the lens, the depth of the pit is set at a value such that the difference between the path of the light reflected at a pit and the Fig. 5. Optical NAND-logic gate VI. OPTICAL MEMORY In optical computing two types of memory are discussed. One consists of arrays of one-bit-store elements and other is mass storage, which is implemented by optical disks or by holographic storage systems. This type of memory promises very high capacity and storage density. The primary benefits offered by holographic optical data storage over current storage technologies include significantly higher storage capacities and path of light reflected at a mirror is an integral multiple of halfwavelength consequently, if there is a pit where light is incident, the amount of reflected light decreases tremendously because the reflected lights are almost cancelled by interference. The incident and reflected beams pass through the quarter wave plate and all reflected light is introduced to the photodiode by the beam splitter because of the polarization rotation due to the quarter wave plate. By the photodiode the reflected light, which as a signal whether, a pit is on the disk or not is changed into an electrical signal. VII. APPLICATIONS 1) High speed communications: The rapid growth of internet, expanding at almost 15% per month, demands faster speeds and larger bandwidth than electronic circuits can provide. Terabits speeds are needed to accommodate the growth rate of internet since in optical computers data is transmitted at the speed of light which is of the order of 3.10*8 m/sec hence terabit speeds are attainable. 2) Optical crossbar interconnects are used in asynchronous transfer modes and Shared memory multiprocessor systems. 3) Process satellite data. VIII. MERITS 1) Optical computing is at least 1000 to 100000 times faster than today’s silicon machines. 2) Optical storage will provide an extremely optimized way to store data, with space requirements far lesser than today’s silicon chips. 3) Super fast searches through databases. 4) No short circuits, light beam can cross each other without interfering with each other’s data 5) Light beams can travel in parallel and no limit to number of packets that can travel in the photonic circuits. 6) Optical computer removes the bottleneck in the present day Communication system IX. DRAWBACKS 1) Today’s materials require much high power to work in consumer products, coming up with the right materials may take five years or more. 2) Optical computing using a coherent source is simple to compute and understand, but it has many drawbacks like any imperfections or dust on the optical components will create unwanted interference pattern due to scattering effects. Incoherent processing on the other hand cannot store phase information. X. SOME CURRENT RESEARCH High performance computing has gained momentum in recent years, with efforts to optimize all the resources of electronic computing and researcher brain power in order to increase computing throughput. Optical computing is a topic of current support in many places, with private companies as well as governments in several countries encouraging such research work. A group of researchers from the University of Southern California, jointly with a team from the University of California, los angles, have developed an organic polymer with a switching frequency of 60 GHz. This is three times faster than the current industry standard, lithium niobate crystal based device. Another group at brown university and the IBM, Alma den research center has used ultrafast laser pulses to build ultra fast data storage devices. This group was able to achieve ultra fast switching down to 100 picoseconds. In Japan , NEC has developed a method for interconnecting circuit boards optically using VCSEL arrays .Another researchers at NTT have designed an optical backplane with free-space optical interconnects using tunable beam deflectors and mirrors. The project achieved 1000 interconnections per printed circuit board; with a throughput ranging from 1 to 10 Tb/s. XI. FUTURE TRENDS The Ministry of Information Technology has initiated a photonic development program. Under this program some funded projects are continuing in fiber optic high-speed network systems. Research is going on for developing Fig.7. Use of optical devices in future New laser diodes, photo detectors, and nonlinear material studies for faster switches. Research efforts on an particle thin film or layer studies for display devices are also in progress. At the Indian Institute of Technology (IIT), Mumbai, efforts are in progress to generate a white light source from a diode case based fiber amplifier system in order to provide WDM communication channels. XII. CONCLUSION Research in optical computing has opened up new possibilities in several fields related to high performance computing, high-speed communications. To design algorithms that execute applications faster, the specific properties of optics must be considered, such as their ability to exploit massive parallelism, and global interconnections. As optoelectronic and smart pixel devices mature, software development will have a major impact in the future and the ground rules for the computing may have to be rewritten. XIII. REFERENCES [1] [2] See for example: Chemical and Engineering ews, â€Å"Photonic Crystals. Assembled on Chip†, 79(47), 31 (2001). P. Boffi, D. Piccinin, M.C. Ubaldi, (Eds.), Infrared Holography for Optical Communications— echniques,MaterialsandDevices,SpringerTopics in Applied Physics: Vol 86, July 2002. Alain Goulet, Makoto Naruse, and Masatoshi Ishikawa, â€Å"Simple integration technique to realize parallel optical interconnects: implementation of a pluggable two-dimensional optical data link†, Applied Optics 41, 5538 (2002) Tushar Mahapatra, Sanjay Mishra, Oracle Parallel Processing, O’Reilly & Associates, Inc., Sebastopol, California, USA, 2000. S. J. van Enk, J. McKeever, H. J. Kimble, and J. Ye, â€Å"Cooling of a single atom in an optical trap inside a resonator,† Phys. Rev. A 64, 013407 (2001). A. Dodabalapur, Z. Bao, A. Makhija, J. G. Laquindanum, V. R. Raju, Y. Feng, H. E. Katz, and J. Rogers, â€Å"Organic smart pixels†, Appl. Phys. Lett. 73 , 142 (1998). Henning Sirringhaus, Nir Tessler, and Richard H. Friend, â€Å"Integrated Optoelectronic Devices Based on Conjugated Polymers†, Science 280, 1741 (1988).

7th Grade Science Fair Projects

Seventh grade and middle school, in general, are a big time for science fairs because its a wonderful educational level for students to come up with ideas to explore using the scientific method and ways to investigate their questions. Parents and teachers still provide direction, especially helping students devise manageable experiments and appropriate work technology to present their results. However, the actual experiment should be done by the 7th grader. The student should record data and analyze it to determine whether or not the hypothesis is supported. Here are some ideas appropriate for the 7th-grade level. 7th Grade Science Project Ideas and Questions Use a prism to show the spectrum of visible light on a sheet of paper. Mark the endpoints, which is how far into infrared and ultraviolet you can see. Compare your visual range with that of other family members or other students. Is there a difference in range between genders? Do family members have a similar range? See if you can draw any conclusions ​using the scientific method.Composting is a great way to reduce waste and recycle nutrients, yet some household products and foods are contaminated with heavy metals and organic chemicals. Devise a test to measure one of these chemicals and compare the concentration in compost versus that in the ordinary soil in your yard.Houseplants can absorb and detoxify indoor pollution. Do research to identify which houseplants are best at cleaning the air in a home, office, or classroom. Now, take the project to the next level and determine which plants are most practical, affordable, and useful. Make a chart of the chemicals the plants cl ean, whether the plants are toxic to children and pets, whether they can live in low-light conditions or require bright light or special care, how much the plants cost, and whether they are readily available.Which brand of ibuprofen (or the student could test another type of pain reliever) dissolves the most quickly?Does the pH of juice change over time?Insects can sense light and dark. Can they still see light if its only red or blue, etc.?How well does a football helmet really protect against impact? You could use a skating helmet or any other protective gear, depending on what you have available.How does the concentration of chlorine in water affect the rate or percentage of seed germination?What is the effect of watering schedules on the germination (or growth rate) of seeds from a certain plant?How does the presence of a given medication in water affect the survivability of Daphnia?Does the presence of de-icer salt affect the movement behavior of earthworms?Does the bounciness of a golf ball relate to its ability to be hit long-distance?Does the species of wood affect the rate at which it burns? Its heat output?Does the mass of a baseball bat relate to the distance the baseball travels?Is the paper towel brand that absorbs the most water the same as the brand that absorbs the most oil?