A microscope: An overview

A microscope: An overview 1. Introduction A microscope is an instrument used to investigate tiny objects which cannot be seen by naked eyes. There exist three types of microscopes which are optical microscopes, electron microscopes, and scanning probe microscopes. (1) Six types of microscopes talked in this report are reflected and transmitted light microscope, scanning electron microscopes (SEM), transmission electron microscopes (TEM), focused ion beam (FIB), and atomic force microscope (AFM). 1.1 Reflected light microscopes Reflected light microscope is a type of microscope using visible light and a system of lenses to magnify images of small samples. It is used to examine opaque specimens which will not transmit light and other materials such as ceramics.The reflected light travels through the objective lens, which in this arrangement acts as both a condenser and an objective, and strikes the specimen.It is then reflected off the specimen back up through the objective lens, the head, the eyepieces, and finally to the eye.(2) 1.2 Transmitted light microscope Transmitted light microscope is a type of microscope where the light transmits from a source on the opposite side of the specimen from the objective. Usually the light is passed through a condenser to focus it on the specimen to get very high illumination. (3)After the light passes through the specimen, the image of the specimen goes through the objective lens and to the oculars where the enlarged image is viewed. 1.3 Scanning electron microscope The scanning electron microscope (SEM) is one kind of electron microscope. The SEM utilizes a very fine probing beam of electrons scanning over the specimen to emit a variety of radiations. The signal which is proportional to the amount of radiation leaves an individual point of the sample at any time. The signal obtained from one point will display the information of that point. In practice, the points follow one another with very high speed so that the image of each point becomes an image of a line, and the line move down the screen so rapidly that the naked eye sees a complete image on the computer. SEMs are patterned after reflecting light microscopes and will yield similar information 1.4 Transmission electron microscope A transmission electron microscope (TEM) works much like a slide projector. A projector shines a beam of light through the slide, as the light passes through it is affected by the structures and objects on the slide. These effects result in only certain parts of the light beam being transmitted through certain parts of the slide. This transmitted beam is then projected onto the viewing screen, forming an enlarged image of the slide. TEMs work the same way except that they shine a beam of electrons through the specimen. Whatever part is transmitted is projected onto a screen for the user to see. TEMs are patterned after transmission light microscopes and will yield similar information. 1.5 Focused ion beam A focused ion beam system (FIB) is a relatively new tool that has a high degree of analogy with a focused electron beam system such as a scanning electron microscope or a transmission electron microscope. In SEM and TEM the electron beam is directed towards the sample generating signals that are used to create high magnification images of the sample. The major difference with a focused ion beam system is the use of a different particle to create the primary beam that interacts with the sample. A highly focused ion beam is used instead of electrons in FIB. As the beam scans the surface of the sample, a highly magnified image is created, which allows the system operator to view the samples microscopic features clearly. 1.6 Atomic force microscope The AFM is one of the foremost tools for imaging, measuring and manipulating matter at the nanoscale. The information is gathered by feeling the surface with a mechanical probe. To achieve atomic scale resolution, a sharp stylus (radius ~1-2 nm) attached to a cantilever is used in the AFM to scan an object point by point and contouring it while a constant small force is applied to the stylus. Piezoelectric elements that facilitate tiny but accurate and precise movements enable the very precise scanning. (4) 2. Study of comparison among six kinds of microscopes 2.1 Optical microscopes Optical microscopes, which use visible wavelengths of light, are the simplest and most used. Both transmitted light microscopy and reflected light microscopy need low energy and the microscope itself is much cheaper and smaller than electron microscopes. Compared to electron microscopes, the optical microscopes have another advantage that the image obtained from them is in color. Comparing to reflected light microscope, the transmitted light microscope only works on light transparent specimens but not metal, ceramics and some polymers such as rubber. However sample preparation of transmitted light microscope is relatively complicated. As it requires sample thin enough for the light to go through. This can be done by using a microtome to slice at lower temperature; as well the distortion of the section due to the sample preparation is a problem for observing. (5) 2.2 SEM The SEM has allowed researchers to examine a much bigger variety of specimens no matter it is bulk or thin layer. The scanning electron microscope has many advantages over optical microscopes.The SEM has a large depth of field, which allows more of a specimen to be in focus at one time.The SEM has much higher resolution (~1-5nm). (5)Because the SEM uses electromagnets rather than lenses, much more control in the degree of magnification can be done.All of these advantages, as well as the actual strikingly clear images, make the scanning electron microscope one of the most useful instruments in research today. However, materials that can be examined in the SEM must be vacuum compatible, clean and electrically conducting such as metal. But for non-conducting materials such as ceramic and polymers, gold or carbon coating on the surface of the sample is essential. 2.3 TEM TEM is a technology using a high energy (80-200kV) beam of electrons to transmit through an ultra thin specimen (50-200nm). High resolution (~0.2nm) is the most significant advantage of TEM. (5) However, there are a number of drawbacks to the TEM technique. Many materials require extensive sample preparation to produce a sample thin enough to be electron transparent, which makes TEM analysis a relatively time consuming process. The structure of the sample may be changed during the preparation process. Also the field of view is relatively small, which leads to the region analyzed may not be characteristic of the whole sample. There is potential that the sample may be damaged by the electron beam, particularly in the case of biological materials. 2.4 FIB FIB is usually used to examine metal surfaces. If the sample is non-conductive, a low energy electron flood gun can be used to provide charge neutralization. FIB is inherently destructive to the specimen because when the high-energy gallium ions strike the sample, they will sputter atoms from the surface. Ga atoms will also be implanted into the top few nanometers of the surface making the surface amorphous. (6) These limitations produce noticeable effects when using techniques such as high-resolution lattice imaging TEM or electron energy loss spectroscopy. 2.5 AFM The AFM is a very high-resolution type of scanning probe microscope, with demonstrated resolution of fractions of 1 nm. (4) AFM provides a true three-dimensional surface profile. Additionally, samples viewed by AFM do not require any special treatments such as coating. Most AFM modes can work perfectly in air or even a liquid environment without a need of vacuum. This makes it possible to study not only metal, ceramic, polymer but also biological macromolecules and even living organisms. In principle, AFM can provide higher resolution than SEM. It has been shown to give true atomic resolution in ultra-high vacuum and in liquid environments. High resolution AFM is comparable in resolution to TEM. A disadvantage of AFM compared with the scanning electron microscope (SEM) is the image size. The AFM can only image a maximum height on the order of 10-20 micrometers and a maximum scanning area of around 150 by 150 micrometers. (4) Another inconvenience is that the AFM could not scan images as fast as an SEM, requiring several minutes for a typical scan, while a SEM is capable of scanning at near real-time after the chamber is evacuated. The relatively slow rate of scanning during AFM imaging often leads to thermal drift in the image making the AFM microscope less suited for measuring accurate distances between topographical features on the image. (4) 2.6 Competition 3. Example of applications 3.1 Reflected light microscope Normally, reflected light microscope is used to image metal, ceramic and rubber. Thats the reason why it is also called metallurgical microscope. Nowadays it becomes a fast growing interest; especially in regard to its increasing usefulness in the fluorescence microscopy as well as the rapidly growing semiconductor industry had also led to an increase in the use of reflected light microscopes. (7) 3.2 Transmitted light microscope Polymers can commonly be looked at under the transmitted light microscope, because most of them are transparent or translucent. It can also analyze cell slices obtained from organism. Most of the lab can afford a transmitted light microscope since it is relatively cheap. 3.3 SEM About any scientific field can use an SEM as a research tool. It can be used to look at the crystalline structures of chemical compounds and how their bonds form. A scanning electron microscope is especially useful for looking at the surfaces of materials at an atomic level. 3.4 TEM TEM can do diffraction analysis of small areas by selected area diffraction. High resolution x-ray microanalysis and analysis of crystal defects such as dislocations, stacking faults using diffraction contrast can also be done by using TEM. Another important application is it can image lattice of crystalline materials. (8) 3.5 FIB FIB can be used as Ion beam imaging. The FIB also offers the ability to perform nanopatterning and micromachining respectively, and by instructing the machine to add or remove pertinent features, operator can design and prototype a new micro or nanostructure, modify integrated circuits and cross section specific features to allow failure analysis even in the 3D (TEM sample preparation). FIB is also used for Secondary ion mass spectrometry (SIMS). (7) The ejected secondary ions are collected and analyzed after the surface of the specimen has been sputtered with a primary focused ion beam. 3.6 AFM The atomic force microscope (AFM) is one of the most powerful tools for determining the surface topography of native biomolecules at subnanometer resolution. AFM allows biomolecules to be imaged not only under physiological conditions, but also while biological processes are at work. The AFM can also provide insight into the binding properties of biological systems. 4. Summary Characteristics of six different types of microscopes are compared in this article, including sample preparation and technique limitations. Each one has its advantage and disadvantage, so it is necessary to consider comprehensively before choosing, for example, the type of the material, needed information, vacuum compatible, conductivity and sample preparation, etc. References Microscopy and Analysis. [Online] http://www.microscopy-analysis.com/. Reflected Light Microscopes. [Online] http://reflectedlightmicroscopes.com/. Wikipidia. Optical microscope. [Online] http://en.wikipedia.org/wiki/optical Microscope. W. Richard Bowen, Nidal Hilal. Atomic force microscopy in process engineering : introduction to AFM for improved processes and products. 2009. Geoff West, John Bates, David Ross, D Grandy, J Perkins. MPP242 Microscopy Handouts. Loughborough: The department of materials, 2009. Peter J. Goodhew, Richard Beanland, John Humphreys. Electron microscopy and analysis. s.l.: Taylor Francis Ltd, 2000. The Royal Microscope socieity. [Online] http://www.rms.org.uk/. Brent Fultz, James Howe. Transmission electron microscopy and diffractometry of materials . 2008.

Power Play in Samuel Beckett’s Endgame Essay -- Samuel Beckett Endgame

Power Play in Samuel Beckett’s Endgame In a shelter devoid of sunlight and laughter, the family in Samuel Beckett’s Endgame all struggle to find their niches within their world. Central to the play physically and emotionally, Hamm has the ability to make the others revolve around him. Clov, physically the healthiest in the family, has a power that even Hamm could not define until very late in the play. Nagg and Nell, the elderly parents of Hamm, hold the power of memories. Although some characters may appear weaker than the others at times, Hamm, Clov, Nagg and Nell all hold a source of power, resulting in a weak type of mutualism in the family dynamics. Hamm is blind and unable to stand. However, sitting in a chair at the centre of the room, he is the axis of power in the family. Hamm repeatedly says, â€Å"Outside of here it’s death† (2475) and, according to Clov’s observations, the world outside has indeed been forsaken by nature and is awash in desolation. Therefore, as the owner of the shelter, Hamm has the power to protect Clov, Nagg, and Nell. Hamm makes the house rules even though he does not have the physical ability to enforce the rules: â€Å"I’ll give you just enough to keep you from dying. You’ll be hungry all the time† (2474). There is nowhere else to go, so in order to survive, everyone abides by Hamm’s commands. Clov humours Hamm, because it is Hamm who took him into the shelter when Clov was a child. With a paternal power over Clov, Hamm has the power to make Clov suffer. He controls Clov like a puppeteer, telling the latter to withdraw or to go close to him. Using Clov as a physical extension of himself, Hamm is able to â€Å"bottle† his father Nagg when the latter complains he is unable to eat the hard bisc... ...dysfunctional family, amidst their painful existence, manages balance their powers and to mutually co-exist. Words have much power, and Hamm retains his grip on his family by his commands. However, Clov – Hamm’s eyes and limbs – has power that matches Hamm’s, because if Clov leaves, no one will be able to physically support them. Nagg and Nell have the power of words and memories, as well as that of listening skills. They are the perfect audience for Hamm, who feels that dialogue is his main reason for living. Without them, Hamm will have no more reasons to continue living. Precariously balanced, the power play in Beckett’s play is like that of its title: an endgame fraught with dangers and overshadowed with doom. Works Cited Beckett, Samuel. Endgame. 1958. Norton Anthology of English Literature. 7th ed. 2 vols. New York: Norton, 2000, 2: 2472-2500.

Consumer Behavior Case Study Do Our Avatars Learn Essay

1) According to the text, classical conditioning occurs when a stimulus that elicits a response is paired with another stimulus that initially does not elicit a response on its own. As time passes, the second stimulus is able to cause a similar response because of the fact that we associate it with the first stimulus. An example of classical conditioning would be one that was demonstrated by Russian physiologist Ivan Pavlov. He conducted research on digestion in dogs. Pavlov was able to induce classically conditioned learning when he paired a neutral stimulus (a bell) with a stimulus that was known to cause a salivation response in dogs (he squirted dried meat powder into their mouths). The powder represented an unconditioned stimulus due to the fact that it was naturally capable of causing the response. As time passed, the bell represented a conditioned stimulus. Initially, the bell didn’t cause salivation. However, the dogs learned to associate it with the meat powder and began to salivate at the sound of the bell only. The drooling of these canine consumers because of a sound, now linked to feeding time, represented a conditioned response. Pavlov demonstrated a basic form of classical conditioning that primarily applies to the responses that the autonomic (e.g., salivation) and nervous (e.g., eye blink) systems control. Meaning, it focuses on visual and olfactory cues that induce hunger, thirst, and other basic drives. When marketers are able to consistently pair these cues with conditioned stimuli, such as brand names, consumers may learn to feel hungry or thirsty when they encounter these brand cues at a later point. This is an example of how classical conditioning can operate for a consumer who visits a new tutoring Web site and is greeted by the Web site’s avatar who resembles Albert Einstein. The individual might not pick of the olfactory cues the first time he visits the Web site, but over a period of time he/she will. 2) According to an online source, instrumental conditioning (also known as operant conditioning) is a form of learning in which an individual modifies the occurrence and form of its own behavior due to the consequences of the behavior. The difference between instrumental conditioning and classical conditioning is that instrumental conditioning deals with the modification of â€Å"voluntary behavior† or operant behavior. Operant behavior â€Å"operates† on the environment and is maintained by its consequences. On the other hand, classical conditioning deals with the conditioning of reflexive behaviors which are elicited by antecedent conditions. Behaviors that are conditioned via a classical conditioning procedure are not maintained by consequences. This is a learning process that we most closely associate with the psychologist B.F. Skinner. Skinner demonstrated the effects of instrumental conditioning by teaching pigeons and other animals to dance, play Ping-Pong, and perform other activities when he systematically rewarded them for desired behaviors. Due to the fact that responses in classical conditioning are involuntary and fairly simple, we make those in instrumental conditioning deliberately to obtain a goal, and these may be more complex. The desired behavior might be learned over a period of time as a shaping process rewards our intermediate actions. From all of this research about instrumental conditioning, we conclude that a consumer who purchases a new outfit for his avatar on a virtual world would be modifying the occurrence and form of the avatar’s behavior due to the consequences of the behavior. 3)I believe that consumers do build associative networks through their avatar’s experience just as they would with any other product or service. The text states that we each have organized systems of concepts that relate to brands, manufacturers, and stores stored in our memories. The contents, however, depend on our own unique experiences. We should think of these knowledge structures, or storage units, as complex spider webs filled with pieces of data. Any information that is incoming gets put into nodes that connect to one another. When separate pieces of information are viewed as similar, we chunk them together under some more abstract category. Then, we are able to interpret new, incoming information to be consistent with the structure we just created. This helps to explain why we are better able to remember brands or stores that we believe â€Å"go together.† Recent research has indicated that people can recall brands that are not as obviously linked. However, in these cases, marketers have to work harder to justify why the two things go together. I do believe that this network is part of the consumer’s overall associative network for that brand. This is because in the associative network, links form between nodes. For instance, the text states that a consumer might have a network for â€Å"perfumes.† Each node correlates to a concept related to the category. This can be an attribute, a specific brand, or a related product. When the consumer is asked to list perfumes, she only recalls those brands that show up in the appropriate category.

Winter Storm essays

Winter Storm essays The white storm that I was caught in happened twenty-seven years ago. The natural disaster I refer to struck on Friday, January 28, 1977, The Blizzard of 77", or as author Erno Rossi, M.A. termed it White Death. What happened on that Friday so long ago was actually a winter hurricane. It had been such a cold, brutal winter. Lake Erie had been frozen solid by Christmas. With extreme temperature and record snowfall, the snow had piled up on top of the ice. So as the 50 mile an hour wind swept across Lake Erie, it blew the powdery snow off the lake, and into Buffalo and the surrounding counties. Into my county it came with a vengeance. I was working as an office clerk at a local linen factory. At that time I did not have my license to drive, so I had to depend on others for my transportation. On this particular day it was my Dad who drove me to work, and who would also drive me home. As we went to work that day it had been snowing heavily. Note enough for us hearty Upstate New Yorkers to stay home though. As the morning had progressed, so had the snow and the wind. My Dad had called me to let me know that he was leaving work early, everyone was being sent home. My Dad came and picked me up at about 12:00 noon. At which point the winds were even stronger and visibility was zero. There we were my Dad and I leaving the city of Batavia to make our six mile trek home in the storm. As we inched our way out of the city we were headed north to our home in Oakfield New York. When I say inched I mean it literally. The windshield wipers couldnt work fast enough to keep the snow off the windshield, the wind was howling around us. We couldnt see. I would roll my window down and pop my head out to see if we were still on the road, but that did little good. So we crept on. It seemed we were alone in this white vacuum. ...

Free Essays on Summary Of “The Scar“

and decides to ... Free Essays on Summary Of â€Å"The Scarâ€Å" Free Essays on Summary Of â€Å"The Scarâ€Å" â€Å"The Scar† is a short story written by Margaret Biggs. The story focuses on fourteen-year-old Chris who struggles hard to face the reality of his damaged arm. Throughout the story, you will get a clear view of what he is thinking about and how he approaches daily difficulties. Chris wakes up early on a Wednesday morning, delighted to be able to see his beautiful English teacher, Mrs. Chadwick whom Chris likes a lot. Just then, he notices the deep, permanent scar on his arm as he recalls the unforgettable car accident four years ago. Since then, Chris’s arm looks so awkward that he wishes it weren’t there. On his way to school, he reflects on his relationship with his best friend Pete; and how he has to give up playing sports because of his injuries. Surprisingly, he meets Mrs. Chadwick somewhere near the school gates. She mentions a drama production she is planning for the class and persuades Chris to audition later in the day. When Chris tells Pete about the issue, Phil Carter interrupts and mocks at Chris’s bad arm. This has made Chris feels desperately miserable. After Science lesson, he finds a seat at the back of the English classroom, still hesitating whether to audition or not. After the scripts are passed around, Pete and Carter have their turns, and Chris gets a chance as well. As soon as it’s two in the afternoon, everybody gathers at the notice board where a list of chosen actors and actresses is posted. Janetta has the part for Lady Treazle and Chris, Sir Peter, the main character. Phil is very unhappy with that and says nasty things to discourage Chris. After giving a thought, Chris decides to give up his role as Sir Peter. Twice in that day, Chris bumps into Mrs. Chadwick. He tells her his decision to quit the drama, but Mrs. Chadwick reassures him by telling him that she was also in an accident years ago and lost one of her legs. Startled by her confession, he ponders over her words and decides to ...

The Unconscious Patient Essay Example | Topics and Well Written Essays - 1500 words

The Unconscious Patient - Essay Example In the case study, Spencer had a GCS of 7/15 and did not respond to verbal commands. However, he responded centrally to painful stimuli. This score is usually associated with a state of coma. Research shows that patients with GCS scores between the range of 3 and 8 are often comatose, or are unconscious such that they cannot interact with their immediate environments. From these information, it is clear that the verbal response on the patient failed and thus some stimuli was needed to obtain a response from him. He was therefore not aware of the surroundings. The Trapezium squeeze was used to twist Spencer’s muscle so that Julia could assess his response to painful stimuli (Sternbach, 2000). I would recommend that Julia also try to observe the patient’s motor response by giving some commands such as â€Å"lift your legs from the bed†,   so that his weaknesses can be noted. In addition, inconsistent and inaccurate recordings could have a harmful effect on the pa tient’s comfort and may affect his care plan. I recommend that Julia or any other nurse handling the patient be educated on how to use the tool correctly so that potential irregularities could be addressed. QN.3. deteriorating changes that may occur as a result of the collapse and how the patient will respond to those changes in his GCS status The patient in this context may experience deterioration in his consciousness provided that there is an underlying problem with his brain due to head injury. When the patient loses consciousness, the tongue often fall back in his pharynx and blocks the airway. He loses the cough reflex, and regurgitated stomach contents or blood are aspirated into his lungs. The patient should therefore have his airway supported by slanting the head and lifting... Factors that can lead to secondary brain injuries include hypercapnia, intracranial hypertension, hypotension, and hypoxia. To prevent these factors, interventions need to begin in the pre-hospital care phase and go on into the critical care unit. Recognizing these factors in the early stages as well as timely intervention can enhance the neurologic effect of the patient with brutal head injuries. One of the oral medications prescribed to treat patients with Diabetes 2 is Glyburide. conventionally used as antiglycemic medication, this drug is meant to block entrà ©e to the sulphonylurea receptors, thus effectively drain edema, intracranial pressure, and swelling brought about by secondary brain injury; consequences that can come about in the days after the initial injury. However, research in animals indicate that glyburide is effective in preventing the adverse effects of secondary brain injury, though it works more effectively if the patient takes it prior to the second injury.

Mobile Computing and Social Networking Essay Example | Topics and Well Written Essays - 1000 words

Mobile Computing and Social Networking - Essay Example For the same reason, health industry has always been a hot spot for research and development thereby attracting lots of investment and renovation. Monitoring of Patient Vital Signs Technology has revolutionized the health care sector to such an extent that one’s blood pressure, blood sugar levels, oxygen levels or respiratory levels all can be measured using mobile technology. Thus the perils of a patient travelling to a doctor’s office for these physiological states to be tested, manual documentation of the readings by a nurse or a clinician and the occurrence of errors while recording the readings etc can be avoided. Above all the greatest advantage is saving the most valuable resource- time. A scenario resembling a science fiction movie where sensors implanted under ones skin detects ones blood sugar level and alerts the doctor is not very far if technological explosion happens at this pace. Today’s technology has made patient’s care very effective. Sma rt phones and broad band enabled devices has allowed patients to do their own monitoring of vital signs and body functions and upload them to their medical provider’s clinical servers. Videoconferencing with their doctor via phones is possible. Not only the patients but also the hospitals are benefitted by the technology. Devices like ECG machines, ventilators, oxygen sensors, blood pressure sensors are connected to the hospital server that records and transmits to the doctor or the nurse to ensure the best care possible. As Shahriyar, Bari, Kundu, Ahamed and Akbar (2010) point out, the use of bio sensor based mobile monitoring system collects data from the patients, mines the data, predicts the patient’s health status, and provides feed back through their mobile phones. So they can access their health information anywhere and anytime. This monitoring system is called Intelligent Mobile Health Monitoring System (pp. 5-6). Advantages As Smith (2011) points out, enhanced patient doctor interaction, accessibility of health care to geographically remote patient, greater exchange of information, increased accuracy of patient records, saving time with diagnosis and treatment of illness, freedom of patience from smoldering hospital rooms and cumbersome medical devices are some of the advantages of monitoring vital signs using mobile computing technology. Wireless networking enables the transmission of signals from the monitor of an ambulance to the emergency room so that the staff is alert to treat the patient as soon as they arrive. The use of mobile technology informs the doctor about the early symptoms of his patients before acute attacks occurs. This is a boon to patients who are reserved in nature as they can express their problems without face to face interaction with the doctor. Doctors also can provide more assistance regarding the treatment and medication which otherwise would have been shortened due to lack of time. Doctors are benefitted in a way that they can focus more on priority tasks. These technologies make the health care system personalized and thereby improve its quality. Disadvantages This technological advancement may not be always an easy task for not so technologically savvy people, especially the older generation. The chances of going offline can cause unprecedented delay in communication between the doctor and the patient. There is a high risk of patient