Contrast introduction. How to Start a Compare and Contrast Essay: Build the Framework 2022-10-28
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A contrast introduction is a type of introduction that is used to introduce two or more subjects that have some significant differences or contrasts. This type of introduction is often used in academic writing or persuasive writing to help the reader understand the main points of the essay and to clearly establish the purpose of the writing.
There are several ways to structure a contrast introduction, but one common method is to start by introducing the two subjects that will be compared and then providing some background information about each. This can be followed by a statement of the main contrast or difference between the two subjects. For example, you might start by saying "Comparing apples and oranges is a common saying, but what do these two fruits really have in common? On the surface, they may seem quite different, with apples being round and firm with a red or green skin and oranges being oval and softer with a bright orange peel. However, upon closer examination, there are also some significant similarities between these two fruits."
Another way to structure a contrast introduction is to begin with a general statement about the two subjects and then provide specific examples or details to illustrate the contrast. For example, you might say "While on the surface, it may seem that cats and dogs are very different animals, there are also many similarities in their behavior and characteristics. Cats are often seen as more independent and aloof, while dogs are known for their loyalty and affection. However, both cats and dogs are intelligent and can be trained to perform a variety of tasks, and they both have the ability to form strong bonds with their owners."
Regardless of how you choose to structure your contrast introduction, it is important to clearly and concisely establish the purpose of your essay and the main points you will be discussing. By providing context and background information about the two subjects you are comparing, you can help the reader understand the significance of the contrast and why it is important to consider.
Compare and Contrast Essay Introduction Example
In order to avoid confusion regarding bright and dark contrast in phase contrast images, the optical path differences occurring within the specimen preparation should be carefully considered. How to Compare and Contrast Two Stories? It would normally be expected that the image of a large phase specimen having a constant optical path length across the diameter would appear uniformly dark or light in the microscope. I will provide a short supplemental video to help further explain. Therefore, it is imaged at a brightness corresponding to the inclination of the refractive index of the sample, and the refractive index distribution of the sample looks three dimensional Figure 2d. Be Creative Try to be as original as possible in your work. As such, the methodology is utilized to examine living cells, tissues, and microorganisms that are transparent under brightfield illumination. And in the conclusion, the thesis statement should be restated and the summary of your points must be presented.
List of 30+ Useful Contrast Transition Words for Writing Essay
It is a way of indicating both the similarity and dissimilarity that go along with two different things. Positive phase contrast plates left-hand side of Figure 6 advance the surround wave by a quarter-wavelength due to the etched ring in the glass plate that reduces the physical path taken by the waves through the high refractive index plate. Other commercial products scrutinized by phase contrast optical techniques include clays, fats, oils, soaps, paints, pigments, foods, drugs, textiles, and other fibers. Yes, you will have to use all of these tips for all papers of this kind you write, and there must be no exception. Compare and Contrast: Basic Features 1. Other than the introduction for compare and contrast essay, your conclusion is the most important part of your paper. Because the rear focal plane usually resides near an internal lens element, some phase contrast objectives are produced by actually etching into the surface of a lens.
Thick specimens are not suitable for this method because the halo appears too strongly. In effect, the absence of destructive interference between low spatial frequency wavefronts diffracted by the specimen and undeviated light waves produces a localized contrast reversal manifested by the halo surrounding the specimen. Interpretation of Phase Contrast Images Images produced by phase contrast microscopy are relatively simple to interpret when the specimen is thin and distributed evenly on the substrate as is the case with living cells grown in monolayer tissue culture. Conclusions Phase contrast is an excellent method for enhancing the contrast of thin, transparent specimens without loss of resolution, and has proven to be a valuable tool in the study of dynamic events in living cells. Wavefronts passing through the annulus illuminate the specimen and either pass through undeviated or are diffracted and retarded in phase by structures and phase gradients present in the specimen.
How to Start a Compare and Contrast Essay: Build the Framework
This section should also comprise your own knowledge on both subjects, and should reaffirm that your thesis statement has been proven. The optical path difference results from the product of two terms: the thickness of the specimen, and its difference in refractive index with the surrounding medium. As a result, the intensity of the central specimen region remains essentially identical to that of the background. In many biological experiments, conditions that produce a shrinking or swelling of cells or organelles can result in significant contrast variations. It is always important to keep the structure of your essay in mind. Observation method Phase contrast method Differential interference contrast method Modulation contrast method Gradient contrast method Thick specimens Bad Good Good Good Can be used with a plastic Petri dish Good Bad Good Good Can observe through a Petri dish with the lid on Bad Good Bad Good Resolution Good Good Passable Good Dedicated objective Required Required Required Not rrequired Switching condenser elements when converting objectives Required Required Required Not required Cost Low High Low Low Table 1.
Below, you will find methods to start writing your college-level compare and contrast essay. Are you going to have four paragraphs — an introduction, a paragraph on the first subject, a paragraph on the second subject, and a conclusion? Since polarization is not used in the modulation contrast method, plastic containers like Petri dishes can be used. In phase contrast microscopy, the intensity of an image does not bear a simple linear relationship to the optical path difference produced by the specimen for the entire thickness and refractive index range. Phase contrast halos are especially prominent and noticeable around large, low spatial frequency objects such as nuclei, diatoms, and entire cells. The diagram is ideal when comparing two subjects, and you want to make things easier and more effective. In optical terminology, phase plates that alter the phase of surround light relative to diffracted light by 90 degrees either positive or negative are termed quarter wavelength plates because of their effect on the optical path difference.
In the central regions of a specimen, both the relative angles and the amount of diffracted light are dramatically reduced when compared to the edges. If someone is going to pick up an essay on the similarities and differences between city and country, chances are they already have a lot of background knowledge on the subject. And the conclusion must be the summarized section of the whole essay, which also includes your own findings. The cell is surrounded by a nutrient medium having a refractive index of 1. At the same time, an allegedly similar Google Glass does not have such entertaining and training possibilities. In contrast, when the refractive index of the surrounding medium exceeds that of the specimen, the wave is advanced in phase upon exiting the specimen. In contrast, the condenser annulus size increases with objective magnification.
4.1: Introduction to Comparison and Contrast Essay
Phase contrast optics differentially enhance the contrast near the edges surrounding extended specimens, such as the boundary between a cellular membrane and the bathing nutrient medium, and produce overall high-contrast images that can be roughly interpreted as density maps. The easiest remedy for removing or attenuating the intensity of halos is to modify the refractive index of the observation medium with higher refractive index components, such as glycerol, mannitol, dextran, or serum albumin. The intensity profile recorded across a central region of the specimen is illustrated in Figure 8 b. Add Some Facts or Humor In the intro, you should provide a 6. Prior to the invention of phase contrast techniques, transmitted brightfield illumination was one of the most commonly utilized observation modes in optical microscopy, especially for fixed, stained specimens or other types of samples having high natural absorption of visible light. There is also considerable interest in development of advanced phase contrast systems that provide accurate measurements of phase specimens having large optical path differences, as well as combined observations with other contrast-enhancing techniques. Or maybe your four paragraphs will be an introduction, the similarities between the two subjects, the differences between the two subjects, and a conclusion? Despite the fact that both of these technologies have somewhat similar approaches, their functional differences are essential.
For a particular phase objective either positive or negative , the optical path difference and specimen size, shape, and structure have significant influence on the severity of halo and shade-off effects. It should be noted that many texts describe the illumination emergent from the condenser of a phase contrast microscope as a hollow cone of light with a dark center. These objectives are designed to furnish positive contrast in specimens having a significant difference in refractive index from the surrounding medium, such as tissue culture cells. It particularly concerns devices of an augmented and virtual reality. Figure 5 - Objective Apertures and Phase Contrast Optics A typical series of phase contrast objectives having increasing magnification, and their corresponding condenser annuli, are presented in Figure 5. In some phase contrast objectives, the thin phase plate contains a ring etched into the glass that has reduced thickness in order to differentially advance the phase of the surround S wave by a quarter-wavelength.
In positive phase contrast Figure 8 c , the specimen image exhibits a distinctively bright halo and demonstrates a dramatic shade-off effect, which is manifested by progressively increasing intensity when traversing from the edges to the central region of the specimen see the intensity profile in Figure 8 d. Take part in community volunteer programs a. For that, you need actual sources and accurate ones. The difference in width between the phase plate ring and surround wavefront is usually around 25 to 40 percent, but is necessary due to restrictions and requirements of the optical design. For most specimens, only a small portion of the incident light waves are diffracted, and a majority of the light passes through undeviated to eventually illuminate the entire image plane. By conducting a more thorough comparison of features of augmented and virtual realities, the most effective application of both technologies can be determined, what will ultimately contribute to their proper development.
Bright medium phase contrast objectives produce bright images on a medium gray background. The shade-off phenomenon is also commonly termed the zone-of-action effect, because central zones having uniform thickness in the specimen diffract light differently than the highly refractive zones at edges and boundaries. Through this process, the essay reveals insights that are interesting to the reader. The differential interference contrast method Figure 1b is a polarized shearing interferometer with complementary Wollaston prisms at the condenser pupil and the objective pupil positions. By utilizing the tips, tricks, and hacks for writing essays in this article, you are sure to have a much easier time writing your compare and contrast essay.