...A serial dilution is a series of sequential dilutions used to reduce a dense culture of cells to a more usable concentration. Each dilution will reduce the concentration of bacteria/yeast by a specific amount. So, by calculating the total dilution over the entire series, it is possible to know how many bacteria/yeast it was started with. Procedure: test tube A is filled with 10 milliliters (mL) of a solution. The second test tube B is filled with 9 mL of a buffer. This buffer will serve to dilute the original solution. The buffer is frequently distilled water, but this actually depends on the composition of the solution in test tube A. The solution is then diluted. 1 mL of solution from test tube A is drawn out with a pipette and transferred to test tube B and mix thoroughly. The solution that originally had a volume of 10 ml now has a volume of 1 mL in test tube B. The solution, therefore, has been diluted by a factor of 10. 1 mL of the solution in test tube B is moved to test tube C using the technique described previously and thoroughly mix the contents of test tube C. The solution in test tube C has been diluted by a factor of 100. The solution in test tube B has 1/10 the concentration of the solution in test tube A and the solution in test tube C has 1/10 the concentration of the solution in test tube B. The solution in test tube C, therefore, has 1/100 (1/10 x 1/10 = 1/100) the concentration of the solution in test tube A. This process may be repeated as many times as...
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...WORKING DILUTION PROBLEMS It is a common practice to determine microbial counts for both liquid and solid specimens--suspensions of E. coli in nutrient broth all the way to soil samples and hamburger meat. Most specimens have high enough numbers of microorganisms that the specimen has to be serially diluted to quantitate effectively. The following is a step-by-step procedure to working dilution problems, and includes some practice problems at the end. The purpose can be determination of bacterial, fungal, or viral counts (indirectly). This protocol is specific for bacterial counts (colony-forming units, CFUs), but can be modified for fungi (CFUs) and viruses (plaque-forming units, PFUs for viral counts). A set of serial dilutions is made, a sample of each is placed into a liquefied agar medium, and the medium poured into a petri dish. The agar solidifies, with the bacterial cells locked inside of the agar. Colonies grow within the agar, as well as on top of the agar and below the agar (between the agar and the lower dish). The procedure described above produces a set of pour plates from many dilutions, but spread plates (sample spread on top of solidified agar) can be used also. The agar plate allows accurate counting of the microorganisms, resulting from the equal distribution across the agar plate. This cannot be done with a fluid solution since 1) one cannot identify purity of the specimen, and 2) there is no way to enumerate the cells in a liquid. Bacterial colonies Viral...
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...Gustavo Duran Per#5 Making Dilutions of Concentrated Solutions Purpose: To make dilutions of concentrated solutions and report their concentration in different ways. Hypothesis: I predict that at least one of the tubes will not change color because of the little concentration it has. Materials: Balance, analytical Balance, tabletop milligram weigh paper, 7.6x7.6 cm weigh boat, 3.5”x3.5” Lab scoops cupric sulfate 5-hydrate Tubes, 15 mL, capped Tube racks for 15mL tubes Deionized water Permanent lab marker pens Tubes, glass, 13x100mm Peg racks for 13x100 mm tubes pipets, 5mL pipet pump, green Spectrophotometer, spectronic 20 D+ Procedure: ● In matrixes similar to those shown in table 3.21 and 3.22, record all your calculations and diagrams. Confirm your calculations with another person’s calculations before you begin. Draw a diagram to show how each sample is diluted. Use the equation to make the calculations. Be sure to make the columns te appropriate width for the material they will contain. ● Label all tubes with the name and concentration of the sample, your initials, and the date. Table 3.21 Dilutions of the 300x stock CuSO4 volume to be made (mL) concentration to be made (x) 5 150x 7 30x 5 15x 5 3x 4 Calculations Volume of stock to use Solution preparation diagram 1x 1. Prepare 25mL of 300-mg/mL CuSO4 solution. Mix well. Do not use previously made solutions. consider this a 300x...
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...particular substance and the quantity of the substance present in the sample or samples, as in this case I have 5 test tubes. The absorption spectrum for cobalt(II)chloride with the color red has a wavelength of 680nm(nanometers). This means that the solution did not absorb a lot of the color red. From the graph we can see that green was absorbed the most which had a maximum wavelength of 551nm(nanometers). Since the green was mostly absorbed, it was not reflected through the sample when hit with light. The absorbance of the cobalt(II)chloride is found first because with that we are able to find out the concentration level by using the formula M1V1=M2V2. For each test tube the concentration levels were different since they each had varying dilutions. After finding the concentration for all 5 test tubes we used logger pro on the computer to create a beer’s law graph. Logger pro then...
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...3 Basic plate count techniques for the enumeration of microorganisms 3.1 Introduction Most of the recommendations and guidelines contained in this chapter are taken from American Public Health Association (APHA), as described in the Chapter 6 of the 4th Edition of the Compendium of Methods for the Microbiological Examination of Foods (Swanson et al., 2001). When different from or complementary to those of the Compendium, they were complemented with information and recommendations from ISO 6887-1:1999 and ISO 7218:2007, recommended for performing tests using methods developed by the International Organization for Standardization. Microbiological examination of foods is predominantly based on culturing techniques, to detect and enumerate living microorganisms. In view of the huge variety and multiplicity of groups, genera and species that may be present, a great number of tests are used, and which can be of one of two types: qualitative tests, which are aimed at detecting the presence or absence of the target microorganism(s), without quantifying, and quantitative tests which determine the quantity of the target microorganism(s) in the sample, generally per unit of weight or volume. Each of these tests follow differentiated procedures, which in turn depend on the target microorganism(s), but most of them utilize the same basic microbiological culturing techniques. These techniques are the detection of presence/absence (Chapter 5), the Most-Probable-Number counts (MPN)...
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...Title: Counting the Number of Yeast Cells in a Suspension using Haemocytometer Objective: To estimate the number of cells of yeast per mm3 in five different dilutions of yeast suspension. Introduction: Biologists often need to count the density of cells in a liquid. “Density of cells” means “the number of cells per unit volume of liquid”. For example, they might want to find out the density of red blood cells in blood plasma, the density of bacteria in milk, or the population of Paramecium sp. (a protozoan) in water from a pond. The simplest, most convenient and cheapest means of accurately determining the number of cells in a sample is to use a haemocytometer and a microscope. A haemocytometer is a specialised slide that has a counting chamber with a known volume of liquid. The haemocytometer is a device originally designed for the counting of blood cells. It is now also used to count other types of cells as well as other microscopic particles. The haemocytometer was invented by Louis-Charles Malassez and consists of a thick glass microscope slide with a rectangular indentation that creates a chamber. This chamber is engraved with a laser-etched grid of perpendicular lines. The device is carefully crafted so that the area bounded by the lines is known, and the depth of the chamber is also known. It is therefore possible to count the number of cells or particles in a specific volume of fluid, and thereby calculate the concentration of cells in the fluid overall. The haemocytometer...
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..."Buyer"). Buyer and Seller shall collectively be known herein as "the Parties". BACKGROUND WHEREAS, Seller desires to sell the vehicle described below, known herein as the "Acquired Vehicle", under the terms and conditions set forth below; WHEREAS, Buyer desires to purchase the Acquired Vehicle offered for sale by Seller under the terms and conditions set forth below; and, therefore, TERMS AND CONDITIONS IN CONSIDERATION of the mutual promises and other valuable consideration exchanged by the Parties as set forth herein, the Parties, intending to be legally bound, hereby agree as follows: A. Description of Acquired Vehicle. 1. Make: HYUNDAI PORTER 2. Model: 1997 3. Serial No.: LMC94-00228-C 4. Motor No.: D4BXL248555 5. Plate No.: UND512 6. File: 1304-00000118567 B. Consideration. 1. Purchase Price. The total purchase price to be paid by Buyer to Seller for the Acquired Vehicle is ONE HUNDRED FORTY THOUSAND PESOS (P140,000.00) (hereinafter "Purchase Price") consisting of the following components: i. Down-payment: P40,000.00 (Due to Seller on or before execution of this agreement.) ii. Remaining balance worth P80,000 payable within one year on installment basis. IN WITNESS WHEREOF and acknowledging acceptance and agreement of the foregoing, Seller and Buyer affix their signatures hereto. SELLER BUYER _______________________________...
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...One Life to Live is a soap opera that was shown on ABC for over 40 years. The show began in 1968 it was created to rival NBC’s popular soap Another World. The Soap’s first sponsor was Colgate-Palmolive. The writer wanted to have less restraint so as to have a wider scope in the story telling. This drama gave the audience a diverse group of characters both ethnically as well as financially showing more than one segment of the population. The show also presented many hard hitting social issues in an accessible manner. One Life to Live followed the Lord family. Actress Erika Slezak played Victoria Lord from March 1971 continuously for the show's entire run. One Life to Live was the last American daytime soap opera taped in New York City. The show was canceled in 2011. The show has been trying for a relaunch but has had some legal issues. Crystal Hunt played the character of Stacy Morasco from 2009 to 2012. The character was a stripper that followed her sister to Llanview after spotting her and Rex Balsom in Vegas. She decided to take rex from her sister because of a misguided obsession. Going through several convoluted plots to make rex hers before she was abducted while pregnant. Through a series of events she ended up dying by falling through ice into a lake. She was survived by her sister Gigi her nephew and her daughter Sierra rose. The actress Crystal Hunt has worked in many daytime shows in addition to her other acting credits. She joined Guiding Light at the age of 17. In...
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...cases people who commit crimes were fatalities of other types of crimes before. There are different types of crimes, but I am going to centre on one type of contemporary crime, which is serial murder, and I will also not forget to look at the incidence, nature, causes and lessening and prevention measures also of serial murder. Understanding Serial Murder/ conceptualisation “South African criminal law defines murder as the unlawful and intentional killing of another person”, Bezuidenhout (2011). In other words the killing must be unlawful in order to be defined as murder. The perpetrator may not be found guilty of murder if she/he claims it was self-defence. Bezuidenhout (2011) , also emphasis that the killing also has to be intentional in order to be labelled as murder. For example if sixteen people die in a car accident. The tax driver may be guilty for not driving like he is expected but he the killing may not be defined a murder. There are many different types of murder, but I will focus on Serial murder. “Serial Murder is defined as the killing of multiple victims over the period of time ranging from days or weeks to months” Adler et al (1996). Adler et al, also emphasis that Serial murders have a minimum of three to four victims. All serial murders turn to have many things in common.“Serial murders tend to be highly mobile in order to minimise the likelihood of establishing links between the murder they commit between various geographic”, Addler (1996). It has been argued...
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...Even though he was not the first serial killer, he was the first killer to strike on a metropolis setting. Jack the Ripper was in his prime at a time when the media had a strong control over society and society had as a whole was becoming much more literate. Jack started his killing campaign at a time of political controversy between the liberals and social reformers along with the Irish Home rule partisans. The reports of Jack the Ripper were collected and reported by the police, but then the different newspapers with their political influences slightly distorted the stories to give them their own effect. It has been more the one hundred years since the last murder and there is no longer any more original evidence, and the "facts" about the stories have changed over time due to different writers or differing sources. The press changed Jack the Ripper from being a depressed killer of prostitutes to one of the most romantic figures seen throughout history. One fact that most sources agreed upon was that the Ripper was a killer who wanted nothing more than to strike fear into the entire city by horribly mutilating his victims and then leaving them in locations where they were sure to be seen. Jack was the type of killer that wants fame and loved the fact that his "name" was on everyone's lips and was able to strike fear into anyone and everyone's heart. In the late 1800's "Jack the Ripper" began his rampage of killings. He was a serial killer who murdered several prostitutes...
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...Gary Leon Ridgway was born in Salt Lake City, Utah and after a string of killings that extended roughly 20 years he was dubbed, by local police, as the Green River Killer. He had admitted to killing over 90 prostitutes and had “lost count because it was so many”. Despite his IQ of 82, he had this serial killing down to a science and evaded police for quite sometime before a DNA test eventually convicted him of a murder and tied him to the whole string of murders that he had committed over the past decade. One has to ask themselves, “What makes a person such a monster?”, in this paper I will attempt to explain what may or may not have contributed to these horrific murders. However it is important to keep in mind that these are theories and not actual factual explanations for these acts of violence. Neurosis is defined as various forms of mental disorders of less violent nature. Now you think how could I have chosen this, “less violent behavior”, when the man killed prostitutes by strangling them, one of the more violent things a person is capable of. I chose it because it includes anxiety disorders which I believe Ridgway must have had that stemmed into his adult life, I based this theory off the fact that his mother would embarrass him in front of family and friends because he had a bed wetting problem later into life than most. Also the list of disorders that neurosis had, one stood out to me, Post traumatic stress disorder or PTS. He did serve in the military during Vietnam...
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...A Reasonably Sane Killer Jeffrey Lionel Dahmer was born may 21st 1960, in West Allis, Wisconsin. He was the son of Joyce Annette and Lionel Herbert Dahmer, and an older brother to David Dahmer. By all accounts he was born into a seemingly normal family, in a middle class white neighborhood. He attended and completed Revere High School, and then attended Ohio State University for a short period of time, but was asked to leave due to his drinking habits. Dahmer underwent Hernia surgery when he was eight years old, and it is said to have changed his personality from that point on. Growing up, Dahmer realized at a young age his fascination with dead creatures. He would patrol his neighborhood for dead animals and then bring them back to his home or the woods and dissect them. Although Dahmer did not torture or kill animals, he had pets of his own at home; he was interested in seeing what was inside of them. At the age of thirteen, Dahmer also had the realization that he was homosexual, causing him major confusion, and sexual frustration. After the age of thirteen he began to distance himself from reality more and more. He suffered from being the victim of bullying all through his school years, due to his strange uncommunicative personality. He was also suffering from loneliness and rejection from his peers and family. Dahmer severely lacked social skills in his teenage and childhood years. At this point in his life he was starting to have very impulsive fantasies and...
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...religion; not everybody who is Muslim is also tied into al-Qaeda. Just because woman/man wear head gear also make them an extremist who is out to bomb something. But because of this tragedy, we have done just that, accused and damned their religion and beliefs; because they are not like us and well because of 9/11. “The Chaser” The movie I chose was “The Chaser”; a movie filmed in South Korea about an ex-detective turned pimp who finds himself in financial trouble because two of his girls disappeared. After sending his last girl, he finds out that the customer is also the last customer of the other two girls who just went missing; in his quest of finding the where about of those two other girls he unfolds the truth. This customer is a serial killer! The reason I chose this movie was first because it was filmed in South Korea, second because I would be able to see how their laws were and how they lived in South Korea. Many stereotypes I have heard over the years: political corruption, violent sex crimes,...
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...Ocpar, Inc. Proposal Bill Johnson Strayer University April 29, 2012 Statement of Need Ocper, Inc. currently has 20 Windows peer-to-peer client computers which are all connected via coax cabling. The president also indicates that the company plans to double in size over the next two years, but she is leery about drastically altering the computer environment. They have indicated that they will possibly be expanding from 20 to 40 users over the next few years. The president has indicated that she would prefer to hold the costs down thought she has indicated that this upgrade is an investment for the future.. My proposal consists of the following: First of all I have proposed to her that they upgrade their PC’s to an Ethernet network which will add more speed and stability to their network. I have suggested that Ocpar buy a total of (20) twenty Intel Gigabit CT PCI Desktop Network adapters at $31.99 per for a total of $639.80. I am also proposing they upgrade their network to a scalable distributed backbone network centralized around a Cisco Small Business 300 Series Managed Switch SF300-24 (24 ports) at a cost of $224.99. The one large item I am proposing to change their network is the purchase of one (1) Dell PowerEdge T310 Server at $3,643.00. This server will suffice what their work is now but it is also something they can grow into. The PowerEdge T310 includes the following: Hard Drives 500GB 7.2K RPM SATA 3.5in Cabled Hard Drive plus one (1) 1TB 7.2K RPM SATA...
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...“The Virtual PC Build” When building a performance PC the first step is to carefully pick the power supply and case it is of upmost importance in a build. It is the very foundation of the computer itself. Without these components you cannot have a functional PC. The Power Supply is very important itself as it delivers the power needed to run all the computer’s components and also provides all the power cables I will need to supply the expansion components that will be installed later in this build. Different devices in the computer and on the motherboard all need different levels of power so to speak so the power supply also reduces and converts the raw electricity into the exact amounts needed by each component by using capacitors and resistors etc. built within the power supply itself. The Case is also very important in this build as I will need a case that can support the motherboard form factor and power supply design I have chosen. The case must also have the needed expansion slots built in and the correct amount of expansion bays for my optical drives. For the power supply I have chosen the OCZ ModXStream Pro 700W Modular High Performance Power Supply, this power supply has everything I need to power all the devices and expansions I will be adding to the computer its specifications are as follow: “Model number OCZ700MXSP, Type ATX12V V2.2 / EPS12V, Maximum Power 700W, 1 x 135mm Fan, Main Connector 20+4Pin, PCI-Express Connector 1 x 6-Pin, 1 x 6+2-Pin, SATA Power Connector...
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