Learn More About the History of Lasers

Learn More About the History of Lasers The name LASER is an acronym for Light Amplification by the Stimulated Emission of Radiation. It is is a device that emits a beam of light through a process called optical amplification. It distinguishes itself from other sources of light by emitting light in a spatially and temporally coherent manner. Spatial coherence keeps the beam within a narrow and tight path over long disances. This allows the energy generated to be used in applications such as laser cutting and laser pointing. Having temporal coherence means that can emit light within a narrow spectrum to generate a light beam of a specific color. In 1917, Albert Einstein first theorized about the process which makes lasers possible called Stimulated Emission. He detailed his theory in a paper titled Zur Quantentheorie der Strahlung (On the Quantum Theory of Radiation). Today, lasers are used in a wide range of technologies including optical disk drives, laser printers and barcode scanners. They are also used in laser surgery and skin treatments as well as cutting and welding. Before the Laser In 1954, Charles Townes and Arthur Schawlow invented the maser (microwave amplification by stimulated emission of radiation) using ammonia gas and microwave radiation. The maser was invented before the (optical) laser. The technology is very similar but does not use visible light. On March 24, 1959, Townes and Schawlow were granted a patent for the maser. The maser was used to amplify radio signals and as an ultra sensitive detector for space research. In 1958, Townes and Schawlow theorized and published papers about a visible laser, an invention that would use infrared and/or visible spectrum light. However, they did not proceed with any research at the time. Many different materials can be used as lasers. Some, like the ruby laser, emit short pulses of laser light. Others, like helium-neon gas lasers or liquid dye lasers, emit a continuous beam of light. The Ruby Laser In 1960, Theodore Maiman invented the ruby laser considered to be the first successful optical or light laser. Many historians claim that Maiman invented the first optical laser. However, there is some controversy due to claims that Gordon Gould was the first and there is good evidence backing that claim. The Gordon Gould Laser Gould was the first person to use the word laser. Gould was a doctoral student at Columbia University under Townes, the inventor of the maser. Gould was inspired to build his optical laser starting in 1958. He failed to file for a patent his invention until 1959. As a result, Goulds patent was refused and his technology was exploited by others. It took until 1977 for Gould to finally win his patent war and receive his first patent for the laser. The Gas Laser The first gas laser (helium-neon) was invented by Ali Javan in 1960. The gas laser was the first continuous-light laser and the first to operate on the principle of converting electrical energy to a laser light output. It has been used in many practical applications. Hall's Semiconductor Injection Laser In 1962, inventor Robert Hall created a revolutionary type of laser that is still used in many of the electronic appliances and communications systems that we use every day. Patel's Carbon Dioxide Laser The carbon dioxide laser was invented by Kumar Patel in 1964. Walker's Laser Telemetry Hildreth Walker invented laser telemetry and targeting systems. Laser Eye Surgery New York City ophthalmologist Steven Trokel made the connection to the cornea and performed the first laser surgery on a patients eyes in 1987. The next ten years were spent perfecting the equipment and the techniques used in laser eye surgery. In 1996, the first Excimer laser for ophthalmic refractive use was approved in the United States. Trokel patented the Excimer laser for vision correction. The Excimer laser was originally used for etching silicone computer chips in the 1970s. Working in the IBM research laboratories in 1982, Rangaswamy Srinivasin, James Wynne and Samuel Blum saw the potential of the Excimer laser in interacting with biological tissue. Srinivasin and the IBM team realized that you could remove tissue with a laser without causing any heat damage to the neighboring material. But it took the observations of Dr. Fyodorov in a case of eye trauma in the 1970s to bring about the practical application of refractive surgery through radial keratotomy.

Evaluating Change Essay Example | Topics and Well Written Essays - 1250 words - 1

Evaluating Change - Essay Example From this study it is clear that the role of change masters in guiding the change process is to examine the present situation alongside the desired future state and to establish the strategic plan towards achieving that objective; however, the most daunting task for change masters is to get others to buy into the change vision and to support it. Most importantly, honoring the past while moving boldly towards the future is imperative for the success of organizational transformation; nonetheless, it is not uncommon for many organizations to be insensitive to, and to disregard their past in the change process by thinking that the old is bad while the new is good. This paper outlines that during the reform initiative at our workplace, the organizational transformation process was sensitive to, and honored all the past organizational successes and accomplishments, which were all attributed to the smoothness and efficiency of the previous work processes. The change agents were careful not to discard everything about the old processes as bad, especially because they are the firm foundation on which the present position of the organization was built. In this respect, past work designs and task allocation among the staff were hailed as the building blocks upon which the previous successes and accomplishments of our organization were found; as such, the change initiative started off by chatting a way forward from the existing organizational work design. The change masters observed that the prevailing work design was effective and only needed minor adjustments to make it water tight in view of the shifting global business environment because of emerg ing challenges and threats to business survival and profitability.  

Theory of contract law Essay Example | Topics and Well Written Essays - 2250 words

Theory of contract law - Essay Example The primary object of courts while construction of a contract is to determine and give effect to the intention of the parties. This fact is elucidated by the eminent judges such as Chief Justice Brian in 1478 held 'that the intention of a man cannot be tried, for the Devil himself knows not the intent of a man'1. And nineteenth century judges such as Lord Eldon who in kennedy v Lee said that it was not the task of his 'to see that both parties really meant the same thing, but only that both gave their assent to that proposition which, be it what it may, defacto arises out the terms of their corresondence.2 And Austin said that 'when we speak of the intention of contracting parties, we mean the intention of the promissor or the intention of the promisee' and he also added that 'the sense in which it is to be inferred from the words used or from the transaction or from both that the one party gave and the other received it'3.Before essaying the subject it is significant to discuss conc isely on other prime factors of a valid contract to which intention of the parties is related to, such as Offer and acceptance and consideration.Offer: Consensus ad idem is the maxim on the offer and acceptance, which means meeting of minds. A contract is made out of an agreement and an agreement is made out of offer and acceptance that means in an agreement one party makes an offer and the other party accepts it. An offer may be an advertisement or a definite offer either to a particular person or to public at large. The law is settled in this respect in Carlill v Carbolic Smoke Ball Co4 in which the company made an offer through an advertisement offering 100 to any person who is affected with influenza after using smoke balls. The plaintiff Carlill has claimed for 100 from the company since she was effected influenza. The company defended that (i) the transaction was only a bet with in the meaning of gaming acts (ii) the advertisement was not intended to create a binding obligatio n (iii) there was no offer to any particular person (iv) no acceptance is notified by the plaintiff. The court of appeal has rejected the grounds taken by the defendant and allowed in favour of the plaintiff. The court while allowing held that there was an offer to the world at large, an offer can be made to the world at large and it also held that by making an offer to the world a contract is made with a limited parties who perform the conditions. Here we can observe that the intention of the advertisement was with an intention to create a legal obligation that is the reason the court has come to a conclusion of existence contract. Offer and an invitation to treat - Intention: The law of contract makes a distinction between offer and an invitation to treat. An invitation to treat does not make a binding contract. When a person responds to an invitation to treat makes an offer. The courts have made distinction between offer and an invitation to treat in auction sale and advertisements. In offer the intention of the parties to create legal obligation where as the in invitation to treat this intention to create legal obligation is premature. Harris v Nickerson5 In this case it was held that an advertisement specifying that goods will be sold by auction do not constitute a promise or offer. It is settled law that an advertisement without further qualification is not an offer to sell the goods but it is only an invitation to treat. The court observed the fact that the intention of the party making an advertisement is to receive the offers from the willing parties and he would select the best offer and intends to withdraw his invitation if he is not receiving the offer he is anticipating or he could accept, therefore there is no legal relationship exists at that particular point of time. The distinction between the offer and invitation to treat was clearly illustrated in Gibson v Manchester City of Council6. Acceptance: When one person makes an offer and such offer is accepted then becomes an agreement. Acceptance is an

Love for Scrambled Tofu Essay Example | Topics and Well Written Essays - 1000 words

Love for Scrambled Tofu - Essay Example Based on the fact that being from an African American origin, the reporter feels more like tofu. This paper outlines how tofu can be related to real life practices and lifestyle. Tofu is the result of the interaction of different cultures in different generations. Having originated from parts of Asia, it has spread to other parts of the world where it is preferred by vegetarians. The spread of tofu is believed to have coincided with the spread of Buddhism since the diet was an excellent source of proteins required in the vegetarian diet of those that followed Buddha. Just like tofu, am dedicated to accomplishing my work. Am loyal to all those around me and have the undying compassion for everyone in my circle. Like tofu is the source of many minerals in our lives, am enthusiastic in learning new things so that I may get the required knowledge to reach my career. Like tofu has essential minerals, he believes in straight-forward lifestyle in order to succeed in life. Tofu’s low-calorie count is what gives it the large amounts of proteins. Also, it has high iron content due to coagulants used during its manufacturing accompanied by high calcium contents. This ensures that tofu is one complete meal for people of all ages. Similarly, my origins have instilled life virtues in him. Am an honest person and have come to learn that being honest costs nothing but can cost one heavily. Also, am a person full of integrity and hate to associate with people who are not straight-forward and live a short-cut free life. Notably, tofu is made from different coagulants that originated from different places and were brought together to form tofu in Asia and my different origins brought me to where he currently lives and instilled the virtues in me. The essay shows that tofu is an origin of different ethnicities coming together to create one cuisine. Mongolians contributed to making of tofu by use of cheese.

Analytical Techniques for DNA Extraction

Analytical Techniques for DNA Extraction Development of DNA sensors for highly sensitive detection of sequence specific DNA has become crucial due to their extensive applications in clinical diagnosis, pathogen detection, gene expression studies, and environmental monitoring.ref Along with complementary base-pair hybridization between long oligonucleotide for DNA detection, several DNA sensors employ short oligonucleotide (à ¢Ã¢â‚¬ °Ã‚ ¤10 base pair) to this goal. Ref Easley and co-workers constructed the electrochemical proximity assay (ECPA) for highly sensitive and highly selective quantitative detection of protein, where target-induced DNA hybridization between 5, 7, or 10 complementary base system brings redox tag close to the sensor surface resulting direct electrochemical readout. To date, numerous analytical techniques have been established for DNA detection, such as electrochemistry, fluorescence, surface plasmon resonance, chemiluminiscence, quartz crystal microbalance and so on. Ref Among these methods, electrochemical DNA (E-DNA) sensors have attracted much attention owing to their reliability, simplicity, rapid response, low cost and portability, low sample consumption, ability to work in complex-multicomponent samples and remarkably high sensitivity and selectivity.ref The basic principle of E-DNA sensor is based on immobilization of single stranded DNA probe, a selective biological recognition element, on a sensor surface followed by incubation with sample containing the target biomolecules. When a target-induced molecular recognition event (hybridization) takes place the sensor translates that to a measurable electrochemical signal which is directly correlated to the target concentration. In recent years, numerous research groups have studied the perf ormance of these sensors by investigating the effect of immobilized probe structure and probe surface density, nature of the redox reporter used, target length, ionic strength of buffer and modifying the frequency of the square-wave voltammetry employed. ref Nevertheless, distance dependence of the redox tag relative to the electrode surface to achieve maximum signal has never been explored. As solid-phase hybridization is very distinct from that in solution-phase in terms of kinetics and thermodynamics, ref sensor performance may be sensitive to the location of the redox reporter because surface charge would likely alter the hybridization rate of negatively charged DNA which, in turn, alters the signaling properties of E-DNA sensors. Especially for short oligonucleotide (à ¢Ã¢â‚¬ °Ã‚ ¤10 base pair) hybridization near surface the effect may lead to very à ¢Ã¢â€š ¬Ã‚ ¦ due to their low binding energy which is not sufficient to overcomeà ¢Ã¢â€š ¬Ã‚ ¦. Here, we describe a detailed s tudy of the extent to which the location of the redox reporter can be varied to achieve maximum signal within shorter response time in effort to design efficient E-DNA sensors with improved sensitivity. Prior to this work, these electrochemical DNA (E-DNA) and electrochemical, aptamer based (E-AB) sensors have been reported against specific DNA and RNA sequences,2 proteins,3,4 small molecules,5-7 and inorganic ions.8,9 Because all of the sensing components in the E-DNA/EAB platform are covalently attached to the interrogating electrode, the approach requires neither exogenous reagents nor labeling of the target. Likewise, because their signaling is linked to specific, binding-induced changes in the dynamics of the probe DNA (rather than changes in adsorbed mass, charge, etc.), these sensors function well when challenged with complex, contaminant-ridden samples such as blood serum, soil extracts, and foodstuffs.5,7,9,10 These attributes render the E-DNA/E-AB platform an appealing approach for the specific detection of oligonucleotides and other targets that bind DNA or RNA.11-13 In the above methods, electrochemical biosensors are much popular because of their simple instrumentation setup, low sample and reagent consumption as well as high sensitivity and selectivity (Wenetal.,2012; Lu etal.,2012; Wenetal.,2011; Farjamietal.,2011; Xia etal.,2010; Xiang andLu, 2012; Pei etal.,2011; Farjamietal.,2013; Liu etal.,2013b). Electrochemical methods,1,11 being simple, portable and low-cost, are particularly attractive for DNA detection.12à ¢Ã‹â€ Ã¢â‚¬â„¢16 Electrochemical methods have been used extensively in DNA detection assays, as summarized in recent review articles.15,16 Among these protocols, the electrochemical biosensors have attracted particular attention in different fields owing to its small dimensions, easy operation, rapid response, low cost, high sensitivity and selectivity [10,11]. Among these techniques, the electrochemical techniques have received great interests owing to its superior characteristics of rapid response, low-cost, small-size, simple operation, and good selectivity [13-16]. Among these approaches, electrochemical methods have been shown to be superior over the other existing measurement systems,11 because electrochemical transduction possesses a potential allowing the development of rapid, simple, low-cost, and portable devices.12-14 As an alternative to conventional techniques, electrochemical DNA biosensors have attracted considerable interest owing to their intrinsic advantages, including good portability, fast response, and remarkably high sensitivity (Sun etal.,2010). More importantly, a number of DNA biosensors have been developed and extensively applied for the determination of biomarkers (Huang etal.,2014). Microfabrication technology has enabled the development of electrochemical DNA biosensors with the capacity for sensitive and sequence-specific detection of nucleic acids.1-5 The ability of electrochemical sensors to directly identify nucleic acids in complex mixtures is a significant advantage over approaches such as polymerase chain reaction (PCR) that require target purification and amplification. Electrochemical DNA sensors are reliable, fast, simple, and cost- effective devices that convert the hybridization occurring on an electrode surface into an electrical signal by means of direct or indirect methods. the electrochemical DNA (E-DNA) sensor is one of them. This sensor platform, the electrochemical equivalent of optical molecular beacons, exhibits notable sensitivity, specificity and operational convenience whilst also being fully electronic, reusable and able to work in complex, contaminant-rich samples [4-6]. Compared with other transducers, electrochemical ones received particular interest due to a rapid detection and great sensitivity. Combining the characteristics of DNA probes with the capacity of direct and label-free electrochemical detection represents an attractive solution in many different fields of application, such as rapid monitoring of pollutant agents or metals in the environment, investigation and evaluation of DNA-drug interaction mechanisms, detection of DNA base damage in clinical diagnosis, or detection of specific DNA sequences in human, viral, and bacterial nucleic acids [2-8]. The determination using electrochemical biosensor methods has attracted much interest because of their simple instrumentation, high specificity, sensitivity, rapid, and is inexpensive with potential for applications in molecular sensing devices. Amongst the electrochemical transducers, carbon electrodes such as glassy carbon, carbon fibre, graphite, or carbon black exhibit several unique properties. Recent engineering advances have enabled the development of electrochemical DNA biosensors with molecular diagnostic capabilities (2, 8, 18, 33, 47). Electrochemical DNA biosensors offer several advantages compared to alternative molecular detection approaches, including the ability to analyze complex body fluids, high sensitivity, compatibility with microfabrication technology, a low power requirement, and compact instrumentation compatible with portable devices (18, 48). Electrochemical DNA sensors consist of a recognition layer containing oligonucleotide probes and an electrochemical signal transducer. A well-established electrochemical DNA sensor strategy involves sandwich hybridization of target nucleic acids by capture and detector probes (5, 7, 46, 50). First reported in 2003, electrochemical DNA (E-DNA) biosensors are reagentless, single-step sensors comprised of a redox-reporter-modified nucleic acid probe attached to an interrogating electrode.1 Originally used for the detection of DNA2à ¢Ã‹â€ Ã¢â‚¬â„¢9 and RNA10 targets, the platform has since been expanded to the detection of a wide range of small molecules,11,12 inorganic ions,13,14 and proteins,12,15à ¢Ã‹â€ Ã¢â‚¬â„¢17 including antibodies,18,19 via the introduction of aptamers and nucleic-acid-small molecule and nucleic-acid-peptide conjugates as recognition elements (reviewed in refs 20 and 21). Irrespective of their specific target, all of these sensors are predicated on a common mechanism: binding alters the efficiency with which the attached redox reporter approaches the electrode due to either the steric bulk of the target or the changes in the conformation of the probe.1,12,18 Given this mechanism, these sensors are quantitative, single-step (washfree), and selective enough to perform well even in complex clinical samples.12,15 They are likewise supported on micrometer- scale electrodes22 and require only inexpensive, handheld driving electronics (analogous to the home glucose meter23), suggesting they are well suited to applications at the point-of-care. Among these, the electrochemical detection of DNA hybridization appears promising due to its rapid response time, low cost, and suitability for mass production.11,12 The E-DNA sensor,13-16 which is the electrochemical equivalent of an optical molecular beacon,17-20 appears to be a particularly promising approach to oligonucleotide detection because it is rapid, reagentless, and operationally convenient.21,22 The E-DNA sensor is comprised of a redox-modified stemloop probe that is immobilized on the surface of a gold electrode via self-assembled monolayer chemistry. In the absence of a target, the stem-loop holds the redox moiety in proximity to the electrode, producing a large Faradic current. Upon target hybridization, the stem is broken and the redox moiety moves away from the electrode surface. This produces a readily measurable reduction in current that can be related to the presence and concentration of the target sequence. Both E-DNA sensors13-16 and related sensors based on th e binding-induced folding of DNA aptamers23-28 have been extensively studied in recent years. Nevertheless, key issues in their fabrication and use have not yet been explored in detail. Electrochemical biosensors, combining the sensitivity of electroanalytical methods with the inherent bio-selectivity of the biological component, have found extensive application in diverse fields because of their high sensitivity with relatively simple and low-cost measurement systems.1 For example, by assembling artful target-responsive DNA architectures on the electrode surface, a series of electrochemical bioanalysis methods have been proposed for the sensing of specific biomarkers, such as DNA and proteins.2-5 The typical sensing schemes of these designs involve the immobilization of an efficient probe on the electrode surface, incubation with target biomolecules, and measurement of the output electrochemical signal.6,7 A wide variety of nanomaterials including metal nanoparticles, oxide nanoparticles, quantum dots, carbon nanotubes, graphene and even hybrid nanomaterials have found attractive application in electrochemical biosensing, such as detection of DNA, proteins and pathogens and the design of biological nanodevices (bacteria/cells).14,15 Electrochemical transducers offer broad opportunities in DNA sensor design due to simple experiment protocols, inexpensive and mostly commercially available equipment. Among various detection methods, the electrochemical approach attracted much attention due to its rapidness, low cost, high sensitivity and compatibility with portability [10,11]. The E-DNA sensor [12,13], an electrochemical method derived from the optical molecular beacon[14,15], is particularly promising because it is reagentlessness andoperation convenience. In brief, the E-DNA sensor is composed of a redox-modified hairpin-like stem-loop DNA probe that is immobilized on the electrode surface. Without a target, the stem-loop structure holds the redox probe close to the electrode surface, pro-ducing a large current. Upon hybridization with a target, the stem is opened and the redox label moves away from the electrode surface and the current is decreased. This current change is directly related to the target DNA concentration. Many different versions of the E-DNA sensor have been reported to date [7-9]. A popular construct of this type of sensors is a folding-based E-DNA sensor comprised of a redox-labeled DNA stem-loop probe covalently attached to a gold disk electrode. In the absence of a target, the stem-loop conformation holds the redox label in close proximity to the electrode, facilitating electron transfer. In the presence of and binding to a complementary DNA target, hybridization forces the redox tag farther from the electrode, impeding electron transfer and producing an observable reduction in redox current [4-6]. In this approach, a single-stranded DNA (ssDNA) probe is immobilized on a surface and exposed to a sample containing the specific complementary target sequence, which is captured by forming a double-stranded DNA(dsDNA) molecule. This recognition event (hybridization) is then transduced into a readable signal. In this strategy, the target is anchored to the sensor surface by the capture probe and detected by hybridization with a detector probe linked to a reporter function. Detector probes coupled to oxidoreductase reporter enzymes allow amperometric detection of redox signals by the sensor electrodes (28, 34). When a fixed potential is applied between the working and reference electrodes, enzyme-catalyzed redox activity is detected as a measurable electrical current (11, 16, 27). The current amplitude is a direct reflection of the number of target-probe-reporter enzyme complexes anchored to the sensor surface. Because the initial step in the electrochemical detection strategy is nucleic acid hybridization rather than enzyme-based target amplification, electrochemical sensors are able to directly detect target nucleic acids in clinical specimens, an advantage over nucleic acid amplification techniques, such as PCR. Electrochemical methods are typically inexpensive and rapid methods that allow distinct analytes to be detected in a highly sensitive and selective manner [22-25]. Although electrochemical DNA sensors exploit a range of distinct chemistries, they all take advantage of the nanoscale interactions among the target present in solution, the recognition layer, and the solid electrode surface. This has led to the development of simple signal transducers for the electrochemical detection of DNA hybridization by using an inexpensive analyzer. DNA hybridization can be detected electrochemically by using various strategies that exploit the electrochemistry of the redox reaction of reporters [26] and enzymes immobilized onto an electrode surface [27], direct or catalytic oxidation of DNA bases [28-31], electrochemistry of nanoparticles [32-35], conducting polymers (CPs) [35-37], and quantum dots [38]. E-DNA sensors, the electrochemical analog of optical molecular beacons [e.g.,1-4], are based on the hybridization-induced folding of an electrode-bound, redox-tagged DNA probe. In their original implementation, the concentration of a target oligonucleotide is recorded when it hybridizes to a stem-loop DNA probe, leading to the formation of a rigid, double stranded duplex that sequesters the redox tag from the interrogating electrode [1]. Follow-on E-DNA architectures have dispensed with the stem-loop probe in favor of linear probes, leading to improved binding thermodynamics and, thus, improved gain [5], as well as strand-invasion, hairpin and pseudoknot probes producing signal-on sensors [6-8]. Because E-DNA sensors are reagentless, electronic (electrochemical) and highly selective (they perform well even when challenged directly in complex, multicomponent samples such as blood serum or soil) [e.g., 9], E-DNA sensors appear to be a promising and appealing approach for the sequence-s pecific detection of DNA and RNA [see, e.g., 10,11]. E-DNA signaling arises due to hybridization-linked changes in the rate, and thus efficiency, with which the redox moiety collides with the electrode and transfers electrons. To design efficient DNA-electrochemical biosensors, it is essential to know the structure and to understand the electrochemical characteristics of DNA molecules. Motivated by the potential advantages of the E-DNA sensing platform, numerous research groups have explored their fabrication and optimization over the past decade. Specifically, efforts have been made to improve the platforms signal gain (change in signal upon the addition of saturating target) by optimizing the frequency of the square-wave potential rampemployed,11 the density with which the target-recognizing probes packed onto the electrode,11,24 probe structure,25 the redox reporter employed,26 and the nature of the monolayer coating the electrode.25 Contributing to these studies, we describe here a more comprehensive study of the extent to which the square-wave voltammetric approach itself can be optimized to achieve maximum signal gain. Specifically, we have investigated the effect of varying the square-wave frequency, amplitude, and potential step-size on the gain of E-DNA sensors, evaluating each parameter as a function of the others as well as of the structure of the E-DNA probe, its packing density, the nature of its redox-reporter, and the monolayer chemistry used to coat the sensing electrode. E-DNA sensors are a reagentless, electrochemical oligonucleotide sensing platform based on a redox-tag modified, electrode-bound probe DNA. Because E-DNA signaling is linked to hybridization-linked changes in the dynamics of this probe, sensor performance is likely dependent on the nature of the self-assembled monolayer coating the electrode. We have investigated this question by characterizing the gain, specificity, response time and shelf-life of E-DNA sensors fabricated using a range of co-adsorbates, including both charged and neutral alkane thiols. The signaling mechanism of E-DNA sensors is linked to a bindingspecific change in the flexibility of the redox-tagged probe; upon hybridization, the relatively rigid target/probe duplex hampers the collision of the electrochemical tag thus decreasing the observable amperometric signal [5,12]. This, in turn, suggests that E-DNA signaling may be sensitive to changes in surface chemistry which, due to surface charge and steric bulk effects, would likely alter the dynamics of a negatively charged DNA probe. However, despite rapid growth in the E-DNA literature [reviewed in 13] the extent to which surface chemistry affects E-DNA signaling has not been established; all previous E-DNA sensors were fabricated using hydroxyl-terminated alkane thiol self-assembled monolayers (SAMs) [e.g.,1,3,5,7,9]. Here we address this question and describe a study of E-DNA sensors fabricated using co-adsorbates of various lengths and charges in an effort to further optimize E-DNA performance. For example, while it is likely that the signaling properties of these sensors depend sensitively on the density of immobilized probe DNA molecules on the sensor surface (measured in molecules of probe per square centimeter) [see, e.g., refs 5 and 29-36], no systematic study of this effect has been reported. Similarly, while it appears that the size of the target and the location of the recognition element within the target sequence affect signal suppression,24 this effect, too, has seen relatively little study. Here we detail the effects of probe surface density, target length, and other aspects of molecular crowding on the signaling properties, specificity, and response time of the E-DNA sensor. However, the sensitivity is one of the most important limiting factors for the development of electrochemical DNA biosensors.

Growth for the Future: Biofuels Essay -- Economics Economy Papers

Growth for the Future: Biofuels The internal combustion engine, so vital for sustaining America's burgeoning economy, is omnipresent in most vehicles from the greatest semis to the smallest economy cars. The combustion engine is also a mode of transportation that is fraught with problems, both costing billions of U.S. dollars to fuel and causing enormous air pollution problems. Iowa, the nation's largest producer of corn and a leading agricultural state, may have the solution to the problems caused by the enormous burden of gasoline and diesel powered engines, biofuel. Biofuels coming out of Iowa include biodiesel, a diesel fuel additive, and ethanol, a gasoline additive. Both are locally produced products that reduce domestic dependence on volatile foreign oil prices, decrease polluting emissions and stimulate the local economy. Every internal combustion engine is built the same. It is composed of a varying number of fuel-saturated gas-filled chambers called cylinders. Each cylinder is expanded and compressed by a piston, driven by a rotating arm called a crankshaft. Every time the piston is pushed into the cylinder, gas inside is compressed to nearly 6 to 10 times atmospheric pressure. At this instant of maximum pressure, the gasoline-saturated air is ignited by a spark and the mixture literally explodes, causing the gas to expand rapidly and force the piston back down, then to come back up again to repeat the process20. When the piston is pushed back down, the crankshaft rotates and performs work which can be harnessed to drive the vehicle. This process, unfortunately, does not capture all of the energy contained in the gasoline, in fact it only uses about one-fifth of the available chemical energy20. Diesel engine... ...hew, "A New Breed of Fuel," Canadian Business. (2002). 14Paulos, Bentham, "Renewable Energy Proposals Are Inadequate, Say Environmental Groups," American Wind Energy Association. (2000). 15Stipp, David, "Why Ethanol Is No Longer a Punch Line," Fortune. (2000). 16Iowa Department of Natural Resources, Energy Bureau, "Switch grass and Other Energy Crops." http://www.sate.ea.us/dnr/energy/pubs/irerg/switchgrass.htm 17Economagic.com, "Unemployment Rate: Iowa." http://www.economagic.com. (2003). 18Iowa Corn, "Where Does America's (Iowa's) Corn Go?" Educational Information. http://www.iowacorn.org/consumption.htm. (2002). 19Renewable Fuels Association, "U.S. Ethanol Industry Today." http://www.ethanolRFA.org. (2002). 20Kraushaar, Jack J. and Ristinen, Robert A., Energy and the Environment, John Wiley and Sons, Inc., New York, 2002), pp. 73-77, 293-299.

Gatsby: Nature of Romantic Love Essay

The Great Gatsby is a story about a man, Gatsby, who is stuck in alternate reality. He is stuck in a past life and wants to remain in it forever. The Great Gatsby reflects a story about the great American dream and, as some may view, a beautiful love story. The Great Gatsby is not a story about perfect love. In fact, it actually mocks the notion that love having no flaws. Fitzgerald writes about the corruption of love and illustrates the obstacles and dangers of corrupted love. The â€Å"love† presented in The Great Gatsby is unethical. Fitzgerald depicts the nature of love in the novel to revolve around obsession, self-destruction, and greed. The Great Gatsby lacks true love and affection to make it a perfect love story. Gatsby is a character with an unrealistic conscience. He is blinded by an idea of love that only he can see. The love he sees is not true love, but in fact an obsession with lust. Helen Fisher, an anthropologist who studies human behavior states in â€Å"The Brain In Love†, â€Å"Romantic love is an addiction†¦a perfectly horrible addiction when it’s going poorly. And indeed it has all the characteristics of an addiction. You focus on the person, you obsessively think about them, you crave them.† This quote taken from a TED Talk portrays Gatsby’s nature of love perfectly. He is addicted to the idea of Daisy. The addiction is horrible because all he does is focus on her and only her. Even though he has not spoken to her in years after the war, he still craves her. It is very clear that Fitzgerald wanted the audience to notice Gatsby’s frightening obsession with Daisy. He follows her every move. He becomes rich for her and buys a mansion for he and holds countless outrageous parties, all because of her. Gatsby says, â€Å"Look at this. Here is a lot of clippings-about you† (Fitzgerald 90). Gatsby documents Daisy’s life. He creates a scrapbook with countless pages regarding Daisy’s life. He collects every possible thing that relates to Daisy. He alters his life to make Daisy love him. â€Å"Infatuation then develops in a specific  psychobiological pattern†¦beginning with intrusive thinking† (The Nature of Romantic Love). This applies directly to Gatsby’s behavior. He consumes his time thinking about Daisy and planning his life accordingly to Daisy’s likes, dislikes, and interests. And after being rejected, the obsession worsens. Daisy has countless flaws including being indecisive, cowardly, and materialistic. She is not the type of person someone would typically fall in love with. But once again, the element of Gatsby’s obsession comes into play. His obsession causes blindness and he is unable to see Daisy’s flaws. In Helen Fisher’s â€Å"The Nature of Romantic Love she states, â€Å"But the limerent casts these flaws aside and fixates on those characteristics that he or she finds unique and charming† (The Nature of Romantic Love). Gatsby’s fixation on Daisy obliges him to only see the good in Daisy that was barely even there anymore. She doesn’t have the best qualities. She has the power to leave Tom, yet she doesn’t. Why? Because she has everything she needs by staying with him. He supplies her with money, luxuries, and lives a comfortable life with him. Daisy puts her wants before the feelings and regards of others. Gatsby is sightless when it comes to pointing out Daisy’s negative qualities. The love presented in The Great Gatsby is self-destructive. It breaks Gatsby and forces him to partake in illegal activities to impress his significant other. The terrible obsession Gatsby has for Daisy causes him to not see the real Daisy. He is in love with the Daisy from the past. This essentially ruins him. He is not in love with the cowardly, shallow Daisy, but the sweet, comforting one from the past. Gatsby’s reality distorts after Daisy leaves him. Helen Fisher states in her TED talk, â€Å"You distort reality. Your willingness to take enormous risks to win this person.† Gatsby does just this. He corrupts and endangers his life because of his willingness to do anything for Daisy. He misrepresents his reality and does not see any harm in part icipating in illegal things. Gatsby takes risks for Daisy. In Helen Fishers TED talk she explains that this is a factor of love. Fitzgerald illustrates this factor in his novel by developing Jay Gatsby’s character into someone who will take massive risks. He is willing to jeopardize his own life to impress Daisy. Tom Buchanan says, â€Å"That’s one of his little stunts. I picked him for a bootlegger the first time I saw him, and I wasn’t far wrong† (Fitzgerald 134). In this statement, Tom is reflecting his opinions on Gatsby, believing that Gatsby  contributes to unjust acts. Tom was correct. Gatsby does partake in illegal activities and slowly destroys his reputation by doing so. People know of Gatsby’s misdemeanors. This is just another example of how unethical the love that exists in the novel really is. The love depicted in The Great Gatsby revolves around greed. The environment Daisy was raised in caused her to only view a materialistic life. Helen Fisher writes, â€Å"Culture, for example, plays an essential role in one’s choice of partner and the timing and process of courting.† Daisy grows up in a very luxurious environment, where money is a factor that contributes to a person’s personality. Why does Daisy suddenly fall back in â€Å" love† with Gatsby when he finally acquires a lot of money? Daisy’s idea of love is blinded with greed. For many years, she forgets about Gatsby when he goes to war and focuses and devotes her life to Tom Buchanan. Tom, a man of wealth, gives Daisy all she need, except love. Tom has multiple affairs with other mistresses, yet this does not bother Daisy. She is content living her life with Tom until Gatsby reveals himself. She falls back in love with Gatsby due to the amount of money he has. Only then does she decide to pursue a relationship with him. Daisy acts like a coward in the novel. Greed is what she has fallen in love with, not Gatsby nor Tom. Dais y’s greed gets in the way of the love that could have been between Gatsby and herself. Daisy’s importance in life orbits around material comforts. She says, â€Å"They’re such beautiful shirts it makes me sad because I have never seen such beautiful shirts† (Fitzgerald 89). The stunning silk shirts represent all of the material luxuries Daisy obsesses over. She has fallen in love with the idea of Gatsby, but not him. Both Daisy and Gatsby confuse greed with love. They long for money and material possessions and corrupt love to fulfill their American Dreams. He believes money will bring him anything, even Daisy’s love. Fitzgerald writes in his novel, â€Å"Gatsby bought that house so that Daisy would be just across the bay. He had waited five years and bought a mansion where he dispensed starlight to casual moths — so that he could ‘come over’ some afternoon to a stranger’s garden† (78). Gatsby spends hundreds of thousands buying a mansion out of greed. He is ravenous for Daisy’s attention. Daisy represents a life filled with luxuries and money and essentially, the Am erican Dream. Gatsby was never able to let that idea go so he devotes the majority of his time to Daisy. Fitzgerald’s novel represents a life full of corruption and mimics the idea of love. It intertwines the ideas of obsession, destruction, and greed among the characters. Gatsby and Daisy’s relationship focuses on the materialism of the era. Instead of truly falling in love with one another, they fell in love with the idea of each other. Gatsby fell in love with the Daisy that no longer existed and Daisy fell in love with what Gatsby represented; greed, money, corruption, and luxuries. The love presented in The Great Gatsby was not love, but an unhealthy infatuation of obsession and greed. Fitzgerald describes the nature of love to be unscrupulous. The characters were not in love, but rather in love with a perfect idea of one another that did not exist.