Water Transitions Essay Example For Students

Water Transitions Essay Water TransitionsBrackish water is a genuinely salty blend of freshwater and ocean water. It isunique from multiple points of view and is a nurturing biological system. To comprehend whatbrackish water is, a foundation ought to be thought about its sources. As a matter of first importance, there is freshwater. Out of all the water on the planet, just threepercent of it is new, and just a single fiftieth of one percent is promptly accessible. Freshwater isn't unadulterated in that it contains minerals and different particles. There arenumerous plants and creatures that rely upon freshwater for their lives. People areone of them. 70% of the human body is comprised of freshwater (744Headlam). Next, there is saltwater, or seawater. Seawater comprises of fifty-five percentchlorine, and thirty-one percent sodium (Groliers). It makes up approximatelyninety-seven and two tenths percent of the complete volume of the universes water, andcovers in excess of 70% of the earths surface (Groliers). Ocean waterdoesnt simply contain hydrogen, oxygen, sodium, and chlorine; it likewise contains everynaturally happening component. Despite the fact that seawater has a genuinely consistent proportion of majorelements, saltiness and seawater can vary. Regular ly, the saltiness is thirty-four tothirty-seven sections for each thousand (ppt.), yet on an especially stormy morning, the salinitymay reduction to something as low as thirty-two ppt. (Stuller 29). The blending of freshwater and ocean water shapes a third kind of water, known asbrackish water. Harsh water can be found in an assortment of blending zones such asriver deltas, freshwater title bogs, estuaries, fjords, and in theocean(Stuller 30). In any case, freshwater going towards the ocean conveys suspendedparticles. As the particles reach saltwater, an electrochemical reactioncalled flocculation happens. The dirt with a positive charge, and the sodiumchloride with a negative charge, consolidate and structure a heavier molecule that descendsto the base of the blending zone and makes a layer of mud (Stuller 28). This is oneof the reasons that a blending zone is a flourishing environment. A salt wedge estuary isone of these transitional zones. The water nearest to the surface has a l ower salinitycontent than the water closest to the estuarys floor in light of the fact that the water is notthoroughly blended and saltwater has a higher thickness than freshwater (Stuller 31). Another zone is a completely blended zone which is obvious in fjords. Likewise, there are zonesin the center of the sea called either submarine springs, or leaks. These arewhere freshwater from under the ground leaks through the sea floor. There isalso an equal circumstance, where salt water can saturate a freshwater ecosystem,but this can be lethal to numerous creatures (Stuller 31). Transitional zones are homes forall sorts of marine life, for example, manatees in Charlotte Harbor. We will compose a custom exposition on Water Transitions explicitly for you for just $16.38 $13.9/page Request now The most predominant blending zones are estuaries. Estuaries are drownedcostal stream valleys where salt and freshwater are available to frame saline water(Groliers). The course in estuaries is delineated with waterway water streaming above seawater with some vertical blending occurring (Groliers). As demonstrated earlier,sediments aggregate at the upper scopes of estuaries due to flocculation. This thus spikes diatom development, diatoms are eaten by possum shrimp, andpossum shrimp are eaten by striped bass. Some other normal fish, present inbrackish water biological systems are mullet and silversides (Groliers). In this manner, the foodcycle proceeds. Salty water has some exceptionally intriguing characteristics. It speaks to solidarity of twovery different biological systems. The blending of seawater and freshwater is extremelybeneficent at the correct time in the perfect spot, yet in the past it might have beenharmful. Researchers estimate that an ice age may have been activated by freshwateroccupying an area where saltwater should have been. There is a deepocean ebb and flow of exceptionally salty water underneath the inlet stream going from the tropicsto the North Atlantic. As it arrives at the North, it upsets surface water, the saltywater rises and releases warmth, and afterward it cycles back to the tropics. What couldhave set off an ice age, a flood of freshwater (Stuller 33). .uf278341500bdb50d74045566fd9c7407 , .uf278341500bdb50d74045566fd9c7407 .postImageUrl , .uf278341500bdb50d74045566fd9c7407 .focused content territory { min-stature: 80px; position: relative; } .uf278341500bdb50d74045566fd9c7407 , .uf278341500bdb50d74045566fd9c7407:hover , .uf278341500bdb50d74045566fd9c7407:visited , .uf278341500bdb50d74045566fd9c7407:active { border:0!important; } .uf278341500bdb50d74045566fd9c7407 .clearfix:after { content: ; show: table; clear: both; } .uf278341500bdb50d74045566fd9c7407 { show: square; change: foundation shading 250ms; webkit-progress: foundation shading 250ms; width: 100%; murkiness: 1; change: haziness 250ms; webkit-progress: darkness 250ms; foundation shading: #95A5A6; } .uf278341500bdb50d74045566fd9c7407:active , .uf278341500bdb50d74045566fd9c7407:hover { obscurity: 1; progress: mistiness 250ms; webkit-change: haziness 250ms; foundation shading: #2C3E50; } .uf278341500bdb50d74045566fd9c7407 .focused content region { width: 100%; position: relat ive; } .uf278341500bdb50d74045566fd9c7407 .ctaText { outskirt base: 0 strong #fff; shading: #2980B9; text dimension: 16px; textual style weight: striking; edge: 0; cushioning: 0; content design: underline; } .uf278341500bdb50d74045566fd9c7407 .postTitle { shading: #FFFFFF; text dimension: 16px; textual style weight: 600; edge: 0; cushioning: 0; width: 100%; } .uf278341500bdb50d74045566fd9c7407 .ctaButton { foundation shading: #7F8C8D!important; shading: #2980B9; fringe: none; outskirt sweep: 3px; box-shadow: none; text dimension: 14px; text style weight: intense; line-tallness: 26px; moz-fringe range: 3px; content adjust: focus; content enhancement: none; content shadow: none; width: 80px; min-stature: 80px; foundation: url(https://artscolumbia.org/wp-content/modules/intelly-related-posts/resources/pictures/basic arrow.png)no-rehash; position: supreme; right: 0; top: 0; } .uf278341500bdb50d74045566fd9c7407:hover .ctaButton { foundation shading: #34495E!important; } .uf278341500bdb50 d74045566fd9c7407 .focused content { show: table; tallness: 80px; cushioning left: 18px; top: 0; } .uf278341500bdb50d74045566fd9c7407-content { show: table-cell; edge: 0; cushioning: 0; cushioning right: 108px; position: relative; vertical-adjust: center; width: 100%; } .uf278341500bdb50d74045566fd9c7407:after { content: ; show: square; clear: both; } READ: Civil rights development EssayCategory: English

The Net Neutrality Laws - Free Essay Example

Kang In early March of 2018, an email service called Tutanota was unavailable for customers of Comcast. Once customers tried to connect to Tutanota with a different ISP (Internet Service Provider) it seemed to work. Consumers began to speculate, and as they thought Comcast had blocked traffic through the site, breaking the net neutrality laws. The FCC (Federal Communications Commission) wants to remove these laws and make it so ISPs can begin to discriminate any data they want, which could mean your favorite apps/websites will potentially be inaccessible. (Whittaker) The Net Neutrality laws should not be repealed because it could affect the internet for Americans negatively forever because your favorite apps or sites such as Netflix, Instagram, and Youtube can be blocked by your internet service provider. Also, these changes will affect anyone who uses the internet for anything. Anything done on the internet is tracked in data types called packets, with repealing net neutrality ISPs can track these packets, and see what sites you are visiting and what you are doing. I should not need to explain how this violates your privacy on many levels. So, you may be wondering, why in the heck would anyone want to get rid of these laws? There are two reasons, the first being that the internet service providers want to make a lot of money, and secondly, people think it will actually help make internet cheaper. People think it will make internet cheaper because the net neutrality laws violate the free market. The free market is a term commonly used in economics that describes the concept that the government has no regulation on how businesses charge their customers. For example, if pizza place #1 sells their pizzas for $10, pizza place #2 will sell theres for $5 so that more people will buy pizzas because they are much cheaper. Its basic economics, the more heavily you regulate something, the less of it youre likely to get. Says Ajit Pai So, in theory, the prices of the internet could go down, because ISPs like Comcast and Verizon will compete, but there is one flaw. That flaw is monopolies, not the fun board game, but rather a problem in economics. A monopoly is when there is only one provider of certain goods or services. Pseudo monopolies are a common thing, and it is when there is one provider to a certain community, like a town. Pseudo monopolies rule the community in their department, whether that be cable, power, or internet. So, how is this a flaw in the free market? Well, the point of the free market is for business to compete, and reduce their prices to gain more customers, in a monopoly, there is no competition, and ISPs will charge as much as they please because consumers will have no competitor to go to. So, imagine if there was one grocery store or restaurant in your area, they would charge very unreasonable amounts due to the supply and demand. So, in conclusion, the repealing of the net neutrality laws put in place by Obama in 2015 will make internet potentially cost more, and it will violate consumers privacy crucially. Even though these new laws are being put in place, it is not too late, Americans need to stand up for their freedom and rule against the laws the FCC is beginning to put in place.

Maths Level Internal Assessment Elimination Of Drug From...

MATHS STANDARD LEVEL INTERNAL ASSESSMENT ELIMINATION OF DRUG FROM THE BODY So, the other day I was watching a show named Grey’s anatomy; it revolves around a medical perspective, this show basically premiers how a hospital works and its base that lies on the ground rule of saving people’s life. This somehow inspired me to study science in high school so that I could pursue some career in medical field and save someone’s life. Having thought of this I sat down wondering what I could possibly do for this assignment, and as I turned around , gazing at the T.V I saw that the nurse was giving some kind of a drug to the patient to relive the pain. This struck me and that’s how I came to a point of utilizing mathematical procedure in pharmacokinetics (the branch of pharmacology concerned with the movements of drugs within the body i.e. the study of elimination and absorption of drugs by the body).I will be evaluating how the drug that is administered to a patient is metabolised and eliminated? More concerns will lie towards the path ways the drug chooses to lose its concentration and I will even be looking at the rate of reactions of these drugs in the body. There are usually five steps in the process of pharmacokinetics: Liberation: Firstly the drug that is administered to the patient is released from the formulation. Absorption: The drug is then absorbed by the body. Distribution: The plasma helps in the distribution of the drug throughout the body. Metabolism: The drug isShow MoreRelatedMedicare Policy Analysis447966 Words   |  1792 PagesSubtitle A—Health Insurance Exchange Subtitle B—Public Health Insurance Option Subtitle C—Individual Affordability Credits TITLE IV—SHARED RESPONSIBILITY Subtitle A—Individual Responsibility Subtitle B—Employer Responsibility TITLE V—AMENDMENTS TO INTERNAL REVENUE CODE OF 1986 Subtitle A—Shared Responsibility Subtitle B—Credit for Small Business Employee Health Coverage Expenses Subtitle C—Disclosures To Carry Out Health Insurance Exchange Subsidies Subtitle D—Other Revenue Provisions rmajetteRead MoreHuman Resources Management150900 Words   |  604 Pagesworkers, most of whom are hourly workers. Making the transition in HR management required going from seven to three levels of management, greatly expanding the use of crossfunctional work teams, and significantly increasing training. 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No part of this publication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the priorRead MoreStephen P. Robbins Timothy A. Judge (2011) Organizational Behaviour 15th Edition New Jersey: Prentice Hall393164 Words   |  1573 Pages10.5/12 ITC New Baskerville Std Credits and acknowledgments borrowed from other sources and reproduced, with permission, in this textbook appear on the appropriate page within text. Copyright  © 2013, 2011, 2009, 2007, 2005 by Pearson Education, Inc., publishing as Prentice Hall. All rights reserved. Manufactured in the United States of America. This publication is protected by Copyright, and permission should be obtained from the publisher prior to any prohibited reproduction, storage in a retrievalRead MoreContemporary Issues in Management Accounting211377 Words   |  846 Pagesof the first to call the British audit profession to account with his questioning of ‘who shall audit the auditors?’ The subsequent institutional response has most likely gained as much from the likes of Professors Harold Edey, Bryan Carsberg, Ken Peasnell, Geoffrey Whittington, and  ´ David Tweedie as it has from the eminence grise of the profession itself. And even in auditing, significant roles have been played by Pro fessors Peter Bird, David Flint, and Peter Moizer amongst others. 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Mau Lo Business Expansion - 1569 Words

Mau Loa – Business Expansion Funding opportunities should be explored and increased for small businesses and entrepreneurs doing business in Atlanta, GA (Fulton County). Georgia State Legislators should use their influence to broaden funding opportunities in the City of Atlanta similar to the funding opportunities enjoyed by start-ups in Silicon Valley (Southern San Francisco Bay area). More specifically, State politicians should consider using their influence to assist young entrepreneurs (under the age of 20 years old) with funding for their small business ventures. There are a few successful business incubators and/or other business initiatives to provide education, training, business mentoring and bank financing in Atlanta, GA. However, a lot of these programs target more established businesses. Younger entrepreneurs find it extremely difficult to find the kind of support to truly launch a viable business concept. Mau Loa, LLC Mau Loa, LLC needs to raise business capital to expand its brand into other markets. For expansion efforts to be successful, Mau Loa needs funding totaling $10,000+. I am an eighteen year old, without established credit, running a business that is grossing under a $2,500 in revenue. I need to secure traditional or non-traditional funding for the expansion of the Mau Loa brand. Background The major issue experienced in the fashion industry is a lack of innovation. The CEO and Founder of Mau Loa, LLC, will function as a positive andShow MoreRelatedOne Significant Change That Has Occurred in the World Between 1900 and 2005. Explain the Impact This Change Has Made on Our Lives and Why It Is an Important Change.163893 Words   |  656 Pagestwenty-four hours and â€Å"not more than one consecutive WORLD MIGRATION IN THE LONG TWENTIETH CENTURY †¢ 11 year for leisure, business or other purposes,† as tourists are described by the World Tourism Organization.5 Much of this mobility is a continuation and expansion of practices that have been going on for centuries: travel for trade and business, the colonization of agricultural lands, the movement of soldiers and sailors, and the constant ebb and flow of forced and free labor

Electrical Submersible Pump Survival Analysis free essay sample

Petroleum Engineer, Chevron Corp. Masters Degree Candidate Advisor Dr. Jianhua Huang With help from PHD Candidate Sophia Chen Department of Statistics, Texas AM, College Station MARCH 2011 ABSTRACT A common metric in Petroleum Engineering is â€Å"Mean Time Between Failures† or â€Å"Average Run Life†. It is used to characterize wells and artificial lift types, as a metric to compare production conditions, as well as a measure of the performance of a given surveillance monitoring program. Although survival curve analysis has been in existence for many years, the more rigorous analyses are relatively new in the area of Petroleum Engineering. We will write a custom essay sample on Electrical Submersible Pump Survival Analysis or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page This paper describes the basic theory behind survival analysis and the application of those techniques to the particular problem of Electrical Submersible Pump (ESP) Run Life. In addition to the general application of these techniques to an ESP data set, this paper also attempts to answer: Is there a significant difference between the survival curves of an ESP system with and without emulsion present in the well? Although survival curve analysis has been in existence for many years, the more rigorous analyses are relatively new in the area of Petroleum Engineering. As an example of the growth of these analysis techniques in the petroleum industry, Electrical Submersible Pump (ESP) survival analysis has been sparsely documented in technical journals for the last 20 years: ? ? ? First papers on the fitting of Weibull Exponential curves to ESP run life data in 1990 (Upchurch) 1993 (Patterson) Papers discussing the inclusion of censored data in 1996 (Brookbank) 1999 (Sawaryn) Paper discussing the use of Cox Regression in 2005 (Bailey) Unfortunately, the papers applying these techniques did little to transfer the knowledge to the practicing Petroleum Engineers. They shared the technical concepts and equations, but not the practical knowledge of how to apply them to real life problems or why these analyses improved upon the â€Å"take the average of the run life of failed wells† technique most commonly used. THEORY OF SURVIVAL ANALYSIS Survival analysis models the time it takes for events to occur and focuses on the distribution of the survival times. It can be used in many fields of study where survival time can indicate anything from time to death (medical studies) to time to equipment failure (reliability metrics). This paper will present three methodologies for estimating survival distributions as well as a technique for modeling the relationship between the survival distribution and one or more predictor variables (both covariates and factors). Appendix A has a list of important definitions relevant to survival analysis. KAPLAN MEIER (NON-PARAMETRIC) Non-parametric survival analysis characterizes survival functions without assuming an underlying distribution. The analysis is limited to reliability estimates for the failure times included in the data set (not prediction outside the range of data values) and comparison of survival curves one factor at a time (not multiple explanatory variables). A common non-parametric analysis is Kaplan Meier (KM). KM is characterized by a decreasing step function with jumps at the observed event times. The size of the jump depends on the number of events at that time t and the number of survivors prior to time t. The KM estimator provides the ability to estimate survival functions for right censored data. ti is the time at which a â€Å"death† occurs. i is the number of deaths that occur at time ti. When there is no censoring, ni is the number of survivors just prior to time ti. With censoring, ni is the number of survivors minus the number of censored units. The resulting curve, as noted, is a decreasing step function with jumps at the times of â€Å"death† ti. The MTBF is the area under th e resulting curve; the P50 (median) time to failure is (t) 0. 5. Upper and lower confidence intervals can be calculated for the KM curve using statistical software. A back-of-the-envelope calculation for the confidence interval is the KM estimator +/2 standard deviations. Greenwood’s formula can be used to estimate the variance for nonparametric data (Cran. R-project): Figure 1: Example Kaplan Meier survival curve showing estimate, 95% confidence interval, and censored data points When comparing two survival curves differing by a factor, a visual inspection of the null hypothesis Ho: survival curves are equal, can be conducted by plotting two survival curves and their confidence intervals. If the confidence intervals do not overlap, there is significant evidence that the survival curves are different (with alpha lt; 0. 05%) COX PROPORTIONAL HAZARD (SEMI-PARAMETRIC) Semi-Parametric analysis enables more insight than the Non-Parametric method. It can estimate the survival curve from a set of data as well as account for right censoring, but it also conducts regression based on multiple factors/covariates as well a judge the contribution of a given factor/covariate to a survival curve. CPH is not as efficient as a parametric model (Weibull or Exponential), but the proportional hazards assumption is less restrictive than the parametric assumptions (Fox). Instead of assuming a distribution, the proportional hazards model assumes that the failure rate (hazard rate) of a unit is the product of: ? a baseline failure rate (which doesn’t need to be specified and is only a function of time) and a positive function which incorporates the effects of factors covariates xi1 – xik (independent of time) This model is called semi-parametric because while the baseline hazard can take any form, the covariates enter the model linearly. Given two obser vations i i’ with the same baseline failure rate function, but that differ in their x values (ie two wells with different operating parameters xk), the hazard ratio for these two observations are independent of time: The above ratio is why the Cox model is a proportional-hazards model; even though the baseline failure rate h0(t) is unspecified, the ? parameters in the Cox model can still be estimated by the method of partial likelihood. After fitting the Cox model, it is possible to get an estimate of the baseline failure rate and survival function (Fox). A result of the regression is an estimate for the various ? coefficients and an R-square value describing the amount of variability explained in the hazard function by fitting this model. Relative contributions of factors/covariates can be interpreted as: ? ? ? gt;0, covariate decreases the survival time as value increases, by factor of exp(? ) ? 0 scale; kgt;0 shape ?(ln(2))1/k The Weibull shape parameter, k, is also known as the Weibull slope. Values of k less than 1 indicate that the failure rate is decreasing with time (infant failures). Values of k equal to 1 indicate a failure rate that does not vary over time (random failures). Values of k greater than 1 indicate that the failure rate is increasing with time (mechanical wear out) (Weibull). A change in the scale parameter, ? , has the same effect on the distribution as a change of the X axis scale. Increasing the value of the scale parameter, while holding the shape parameter constant, has the effect of stretching out the PDF and survival curve (Weibull). Figure 2: Example Weibull curves with varying shape scale parameters The Weibull regression model is the same as the Cox regression model with the Weibull distribution as the baseline hazard. The proportional hazards assumption used by the CPH method, when applied to a survival curve with a Weibull function baseline hazard, only holds if two survival curves vary by a difference in the scale parameter (? ) not by a difference in the shape parameter (k). If goodness of fit to the Weibull distribution can be achieved, a confidence interval can be calculated for the curve, the median value and its confidence interval can be calculated, and a comparison of the differences in two survival curves can be conducted. Goodness of fit can be tested in R using an Anderson Darling calculation and verified with a Weibull probability plot. Poor fit in the tails of the Weibull distribution is a common occurrence for reliability data due to infant mortality and longer than expected wear out time. STEPWISE COX W EIBULL REGRESSION Given a large number of explanatory variables and the larger number of potential interactions, not all of those variables may be necessary to develop a model that characterizes the survival curve. One way of determining a model is by using Stepwise model selection through minimization of AIC (Akaike Information Criterion). This model selection technique allows variables to enter/exit the model using their impact on the AIC calculated at that step. AIC is an improvement over maximizing the R-Square in that it’s a criterion that rewards goodness of fit while penalizing for model complexity. APPLICATION TO AN ESP DATA SET As stated previously, these survival analysis techniques can be applied to many types of data in many industries ranging from survival data for people in a medical study to survival data for equipment in a reliability study. These methodologies have many uses in the petroleum industry; from surface equipment system and component reliability used by facility and reliability engineers, to well and downhole system and component reliability used by petroleum and production engineers. As an example, this paper illustrates the use of these techniques on the run life of Electrical Submersible Pumps (ESP). ESPs are a type of artificial lift for bringing produced liquids to the surface from within a wellbore. Appendix B includes a diagram of an ESP. For this paper, the run life will refer to the run life of an ESP system, not the individual components within the ESP system. While this paper focuses on ESP systems, these same techniques could be applied to other areas of Petroleum Engineer interests including run life of individual ESP components, other types of artificial lift, entire well systems, etc. DATA DESCRIPTION ESP-RIFTS JIP (Electrical Submersible Pump Reliability Information and Failure Tracking System Joint Industry Project) is a group of 14 international oilfield operators who have joined efforts to gain a better understanding of circumstances that lead to a success or failure in a specific ESP application. The JIP includes access to a data set of 566 oil fields, 27861 wells, 89232 ESP installations, and 182 explanatory factors/covariates related to either the description of the ESP application or the description of the ESP failure. For the analysis described in this paper, a subset of the data has been used, restricted to: ? ? ? ? ? ? Observations related to Chevron operated fields observations with no conflicting information (as defined by the JIP’s data validation techniques) factors that were related to the description of the ESP application (excluded 27) factors not confounded with or multiples of other factors (excluded 30) factors with a large number (gt;90%) of non-missing data points (excluded 78) factors that were not free-form comment fields (excluded 27) Appendix C has a list of the original 182 variables with comments on why they were removed from the analyzed data set, below is a table of the 20 remaining explanatory variables included in this analysis. SUMMARY TABLE OF DATA INCLUDED IN THE CPH/REGRESSION ANALYSIS: OBSERVATIONS: 1588 DESCRIPTION RunLife Censor Country Offshore Oil Water Gas Scale CO2 Emulsion CtrlPanelType NoPumpHouse PumpVendor NoPumpStage NoSealHouse NoMotorHouse MotorPowerRating NoIntakes NoCableSys CableSize DHMonitorInstalled DeployMethod COVARIATE/FACTOR # OF LEVELS Response Censor Flag (0, 1) Factor (7 levels) Factor (2 levels) Covariate Covariate Covariate Factor (5 levels) Covariate Factor (3 levels) Factor (2 levels) Covariate Factor (2levels) Covariate Covariate Covariate Covariate Covariate Covariate Covariate Factor (2 levels) Factor (2 levels) DESCRIPTION Time between date put on production and date stopped or censored 1 if ESP failure 0 if still running or stopped for a different reason Country Field in which the ESP is operated Indication of whether the ESP was an onshore or offshore installation Estimated average surface oil rate (m3/day) Estimated average surface water rate (m3/day) Estimated average surface gas rate (1000m3/day) Qualitative level of scaling present in the well % of CO2 present in the well Qualitative level of emulsion present in the well Type of surface control panel used Number of pump housing s Pump Vendor Number of pump stages Number of seal housings Number of motor housings Motor rated power at 60Hz (HP) Number of intakes Number of cable systems Size of cable Flag for installation of a downhole monitor Method of ESP deployment into the well FINDING THE P50 TIME TO FAILURE FOR A DATASET Example 1: Using the entire data set, what is the P50 estimate for the runtime of a Chevron ESP? The answers differ considerably for the 4 calculation types: METHODOLOGY Mean or Median Kaplan Meier Median CPH Median INCLUDES CENSORED? No Yes Yes P50 ESTIMATE (DAYS) Mean: 563 Median: 439 1044 1043 ASSUMPTION None None None (as no comparison of levels/covariates, essentially same results as KM) Anderson Darling GOF for Weibull Distribution N/A N/A N/A ASSUMPTIONS MET ? Weibull Median Yes 1067 NO (rejected the null hypothesis of good fit, due to poor fit in the tails) In this example, the biggest impact on the difference between the methods is the inclusion of censored data. A large number of the ESPs in this data set have been running for gt;3000 days without a failure and were excluded in the often used calculation of the average run life of all failed ESPs. Given that the Weibull distribution did not pass the Anderson Darling goodness of fit test, the most appropriate calculation would have been the KM or CMH. Appendix E has the output from the various methodologies. The interpretation of these results is that the P50 estimate of run life for an ESP installation in Chevron is ~ 1044 days. Additional, output from the KM analysis sets the 95% confidence interval at 952 to 1113 days. Figure 3: Comparison of estimation methods for full data survival curve. Note the deviation of the Weibull in the tails of the data. COMPARING TWO SURVIVAL CURVES DIFFERING BY A FACTOR Example 2: Using the 2 level factor emulsion, does the presence of emulsion in the well make a significant difference in the P50 run life of an ESP system? METHODOLOGY Mean or Median Kaplan Meier Median CPH Median INCLUDE CENSOR? No Yes Yes EMULSION P50 (DAYS) Mean 600 Median 458 606 533 NO EMULSION P50 (DAYS) Mean 536 Median 424 1508 1408 SIGNIFICANT DIFFERENCE? Don’t know Yes (visual Inspection of CI) Yes, with a Likelihood ratio test and a pvalue of 0, reject that B’s are the same. Yes, with a z test statistic and a pvalue of 0, reject that the scale values are the same. INTERPRETATION Well performance is about the same Wells without emulsion perform much better Wells without emulsion survive longer. Exp(B) indicates 2. 5 times increased survival time for no emulsion. Wells without emulsion survive longer. Scale parameter value indicates 2. 75 times increased survival time for no emulsion. ASSUMPTIONS MET ? No. (Reject null hypothesis of prop. hazards with a p value of 0. 01. ) No. Reject null hypothesis of good of fit due to poor fit in the tails) Weibull Median Yes 531 1463 The more complex the methodology used, the more information is available to interpret the results. Again, the addition of censored data resulted in a very different interpretation of the data than just using the mean/median value of all failed ESPs; not just in the order of magnitude of the results, but also determination of which condition resulted in a longer run life. The results of both the CPH Weibull methodologies are suspect due to their failure to meet the prerequisite assumptions. Looking at the plots, it is apparent that the fit is poor in the tails. Appendix F has the output from the various methodologies The interpretation of these results is that wells without emulsion have gt; a 2x increase in their P50 run life than wells with emulsion. It should be noted that given the other factors that differ in the operation of these ESPs, this difference may not be fully attributed only to the difference in emulsion, but this interpretation should lead to further investigation. Figure 4: KM estimated survival curves for ESPs with and without emulsion with confidence interval Figure 5: Comparison of estimation methods (KM, CPH, Weibull) for ESPs with and without emulsion CHOOSING THE VARIABLES THAT CHARACTERIZE A SURVIVAL CURVE Example 3: Of the variables collected by the JIP, which most describe the survival function? Do the variables collected in the dataset capture the variation in the survival function? As stated previously, both Weibull Cox regression fit a model using explanatory variables. The introduction of Stepwise variable selection to that regression allows the preferential fitting of the model by minimizing the AIC. As Weibull regression is a special case of Cox regression with a Weibull baseline hazard function, and as Cox regression has less restrictive assumptions than parametric regression, this example will focus solely on Cox regression using Stepwise

Sylvia Plaths Novel, The Bell Jar Is Often Considered A Literary Clas

Sylvia Plath's novel, The Bell Jar is often considered a literary classic for its description of the protagonist's angst ridden journey through depression. In the autobiographical novel, Esther Greenwood, Plath's protagonist, sinks into a profound depression after her third year at college during the 1950's. Esther battles not only a deteriorating mental stability, but also a lack of a sense of individuality, which leads to her major depressive disorder. Esther is a sensitive and intelligent woman who feels oppressed by the obvious social restrictions placed upon her, along with the pressure she feels regarding her future. Esther feels overwhelmed and powerless to break free of the emotional burdens of her inner world of alienation and depression. Her story of the overcoming of depression leads the reader through a story of dependency, self-criticism, and inefficacy all to become healthy once again. The novel begins in New York City, during the summer after Esther Greenwood's third year at college. Esther spends the month of June interning at a ladies' fashion magazine in Manhattan, after winning a scholarship for her writing. During her time as an intern, she becomes uninterested in the work, despite her initial expectations, and increasingly unsure of her own prospects. Esther shows the beginning signs of depression, with self-doubt along with paranoia, when faced with the possibilities of career and success as a writer. Essentially an outcast among the other 12 girls who won scholarships, Esther's numerous attempts at social conformity fail, as her image of herself is incomplete and contradictory. When returning home to the suburbs of Boston, her mother tells her she did not make a writing course she applied to, a devastating blow to Esther also grows disenchanted with her boyfriend, Buddy Willard. Her sleep and eating patterns decrease and become irregular as she falls deepe r into the stages of depression. She goes to see a psychiatrist, Dr. Gordon but he proves to be not much help to Esther's condition and advises shock therapy, which she comes to hate. Meanwhile, Esther is obsessively contemplating suicide. She decides to overdose on sleeping pills, but her death is prevented. She is taken to a city hospital and then, through the financial intervention of a benefactor, to a private psychiatric institution. She is treated by Dr. Nolan, a female psychiatrist whom Esther grows close to. . Esther undergoes a more successful procedure of shock therapy, after which she feels the bell jar of depression lifting. Esther's therapy allows her to recover from depression, and she leaves the hospital patched, retreaded and approved for the road. Esther, along with the reader, is aware of her mood disorder throughout the whole novel. She suffers from the psychological disorder of major depression. Her recurrent depression lasts until her treatment in the hospital, towards the end of the book. Esther's symptoms begin with anxiety, fatigue, and agitated behavior. Her disorder interferes with her sleep patterns along with the ability to concentrate and interact with others. Esther's emotions increase and seriously threaten her health and life when it leads to suicide attempts. Depression often leaves its victims with the sense that it will go on forever and they are helpless, but luckily for Esther, she receives therapy to overcome it. Her first psychiatrist diagnoses Esther as depressive, and he recommends electrical shock therapy to help her. This proves to be ineffective, and she comes to loathe it. After attempting suicide, she is placed in a private mental hospital under the care of Dr. Nolan. Dr. Nolan prescribes anti-depr essive medicine along with the discussing Esther's problems and a different type of shock therapy. Slowly, Esther's condition begins to become better. The novel ends with Esther happily describing herself as ready to enter the world freely. The novel of Esther?s triumph over her depression is both an informative book on depression along as entertaining and intriguing. The emotional burdens she faces at the time result not only in Esther's social and intellectual isolation, but also her impending mental breakdown. The classic provides the reader with a revealing look into the disorder of depression through the year in the life of Esther Greenwood. I would recommend this novel for any mature reader.

Locations as Metaphors in The Great Gatsby essays

Locations as Metaphors in The Great Gatsby essays F. Scott's Fitzgerald's novel The Great Gatsby often uses locations as metaphors for the qualities of the characters and for the themes of the novel. This occurs with West Egg and East Egg, where the distance between the two sides represents Gatsby's distance from Daisy, his longing for his dream, and the fact that the dream may not be attainable. West Egg and East Egg also represent the differences in the characters of Gatsby and Daisy, especially communicating that Gatsby's attempts to reinvent himself can only take him so far. The valley of ashes is also important because it contributes to the theme of the novel by showing the result of wealth. The all-seeing eyes of the billboard looking over the valley of ashes also represents that the characters cannot escape judgement. These metaphors all contribute to the theme of how money is not the solution to life, but The first metaphor occurs with West Egg and East Egg, two egg-shaped islands lying opposite each other and separated by a bay. West Egg is the island where Gatsby lives and also the less fashionable of the two islands. While West Egg is less fashionable, it is also the more real of the two islands. This includes that it is the island where the narrator Nick lives in a small rented bungalow. West Egg still has its share of mansions but there is also a sense of reality to the place. In contrast, East Egg is all mansions, with the sense of elite making it the least real of the two islands. The first reason this location is relevant is because it represents Gatsby's physical separation from Daisy and his longing for her. Gatsby lives on West Egg and Daisy lives on East Egg. This makes Gatsby quite close to her, yet he remains separated by the body of water. His longing is captured by the way he gazes across the bay at the green light "that burns all night at the end of your dock" (Fitzgerald 94). Nick ...