bluuebunny/crossref_metadata_2025 huggingface dataset:
Theory of Damage Detection Using Constrained Vibration Deflection Shapes
Authors: Schulz Mark J. , Ghoshal Anindya , Sundaresan Mannur J. , Pai P. Frank , Chung Jaycee H.
Published: April 2009

Various techniques have been developed that use changes in the mode shapes, Ritz vectors, or the operational deflection shapes of a structure to detect damage. These techniques generally have been applied using single excitation forces at low frequencies. This paper shows that the frequency range and number of simultaneous excitation forces used significantly affects the sensitivity of damage detection. Based on this idea, a model independent method of damage detection using measured constrained vibration deflection shapes (VDS) and predamage data is presented. The constrained VDS are the vibration shapes of the structure that occur when the forcing vector contains elements that cause the structure to vibrate in a desired pattern. The method is analytically tested using a finite-element model of a fixed-fixed beam wherein simulations are performed using one and two rotational excitations, and then a prescribed excitation vector that is comprised of the rotational degrees-of-freedom (DOFS) of one of the mode shapes of the healthy structure. The rotational excitation is used because it is convenient to apply at a large number of locations on the structure using thin piezoceramic patches. The translational vibration of the beam is used in the damage detection algorithm because the translational DOFs are convenient to measure using a scanning laser vibrometer. The simulations show that small damage can be located using distributed high frequency excitation applied as a symmetric mode shape at the rotational DOFs of the beam.
Damage Detection Using Optical Measurements and Wavelets
Authors: Patsias S. , Staszewskiy W. J.
Published: April 2009

The paper presents an application of the wavelet transform for damage detection based on optical measurements. A number of important issues that need to be considered when image sequences are used for vibration analysis are discussed. These include: correspondence of image features from image to image, image calibration and spatial resolution. The principles of image edge detection are discussed and a comparison between the wavelet approach and the classical method is presented. A novel damage detection method based on optically measured mode-shape data is proposed. The method is illustrated using a simple cantilever beam experiment. The major advantage of the method is the significantly increased number of discrete points used to describe mode shapes. This is in contrast to classical techniques where in practice a small number of measurement points are obtained from a limited number of sensors.
Piezoelectric Wafer Embedded Active Sensors for Aging Aircraft Structural Health Monitoring
Authors: Giurgiutiu Victor , Zagrai Andrei , Jing Bao Jing
Published: April 2009

Piezoelectric wafer active sensors may be applied on aging aircraft structures to monitor the onset and progress of structural damage such as fatigue cracks and corrosion. The state of the art in piezoelectric-wafer active sensors structural health monitoring and damage detection is reviewed. Methods based on (a) elastic wave propagation and (b) the Electro-Mechanical (E/M) impedance technique are cited and briefly discussed. For health monitoring of aging aircraft structures, two main detection strategies are considered: the E/M impedance method for near field damage detection, and wave propagation methods for far-field damage detection. These methods are developed and verified on simple-geometry specimens and on realistic aging aircraft panels with seeded cracks and corrosion. The experimental methods, signal processing, and damage detection algorithms are tuned to the specific method used for structural interrogation. In the E/M impedance method approach, the high-frequency spectrum, representative of the structural resonances, is recorded. Then, overall-statistics damage metrics can be used to compare the impedance signatures and correlate the change in these signatures with the damage progression and intensity. In our experiments, the (1 R2)3 damage metric was found to best fit the results in the 300-450 kHz band. In the wave propagation approach, the pulse-echo and acousto-ultrasonic methods can be utilized to identify the additional reflections generated from crack damage and the changes in transmission phase and velocity associated with corrosion damage. The paper ends with a conceptual design of a structural health monitoring system and suggestions for aging aircraft installation utilizing active-sensor arrays, data concentrators, wireless transmission, and a health monitoring and processing unit.
Detection of Defects in Circular Plates using a Scanning Laser Vibrometer
Authors: Pai P. Frank , Oh Yunje , Lee Seung-Yoon
Published: April 2009

This paper investigates dynamic characteristics (mode shapes and natural frequencies) and defect detection of circular plates using a scanning laser vibrometer. Analytical dynamic characteristics of a circular aluminum plate having a clamped inner rim and a free outer rim are obtained using two methods; one uses Bessel functions and the other uses a multiple shooting method. An in-house finite element code GESA is also used to analyze the circular plate using the DKT plate element. Numerical results show that high-frequency Operational Deflection Shapes (ODSs) are needed in order to locate small defects. Detection of two defects in the circular aluminum plate is experimentally studied using the distributions of RMS velocities under broadband periodic chirp excitations, RMS velocities of ODSs, symmetry breaking of ODSs, splitting of natural frequencies and ODSs, and a Boundary Effect Detection (BED) method. The BED method is a dynamics-based non-destructive method; it processes experimental ODSs to reveal extra local boundary effects caused by defects to reveal locations of defects. Experimental results show that small defects in circular plates can be pinpointed by these approaches. Moreover, a new concept of using the balance of elastic and kinetic energies within a mode cell for detecting defects in two-dimensional structures of irregular shapes is proposed.
Successive Free Listing: Using Multiple Free Lists to Generate Explanatory Models
Authors: Ryan Gery W. , Nolan Justin M. , Yoder P. Stanley
Published: April 2009

Successive free listing is a data collection technique that links multiple free lists together in a single interview. The technique can be incorporated into naturally occurring conversations and is readily understood by informants. It also generates more information about the similarity between items than do standard free-listing tasks and allows investigators to better describe intracultural variation among informants. Data from Yoder's ethnomedical study of childhood diarrhea in Zaire are used to demonstrate how the technique works and how the data can be analyzed. The authors warn that successive free listing is not a substitute for more formal frame substitute techniques, and investigators may wish to use the technique early in the research process to systematically explore and describe the multiple relationships between items in a domain.
Uses of a Fish-Eye Lens
Authors: Werner Oswald
Published: April 2009

Most wide-angle lenses are not wide enough to show an entire room with material possessions in context. However, such wide coverage can be accomplished with a fish-eye lens. Recently, fish-eye auxiliary lenses have become available at low cost, making them affordable for most ethnographers. The author demonstrates the usefulness of a fish-eye lens with a photograph of his living room in Albuquerque. The limitations of standard lenses are shown with Vicos (Peru) photographs by John Collier, Jr. Fish-eye lenses can also be used to document the personnel present at meetings.
Application of General Utility Theory for Estimating Value in Non-Western Societies
Authors: Kuznar Lawrence A.
Published: April 2009

Understanding value and being able to monitor it is crucial to many anthropological theories of economy. The author presents a method, developed in economics, of evaluating peoples' subjective values. While this method is derived from neoclassical economics, its assumptions are minimal and its use is not necessarily tied to any particular economic paradigm. Therefore, the method may be useful to anthropologists working within neoclassical, ecological, Marxist, or interpretive paradigms.
Using Guttman Scaling to Rank Wealth: Integrating Quantitative and Qualitative Data
Authors: Guest Greg
Published: April 2009

Wealth ranking in given field sites can be problematic for a number of reasons. This article explores the usefulness of Guttman Scaling and AnthroPac software in such contexts, using a small fishing community on the northern coast of Ecuador as an example. The author provides a step-by-step description of procedures for implementing and analyzing Guttman Scale methodology and discusses the issue of construct validity. The complementary relationship between qualitative and quantitative data is highlighted throughout.
Can Qualitative Research Produce Reliable Quantitative Findings?
Authors: Green Edward C.
Published: April 2009

This article asks whether qualitative anthropological research using rapid methods can produce results as reliable and valid as those derived from expensive sample surveys, at least under certain circumstances. The discussion focuses on nonformal sampling or informant selection techniques on which anthropologists rely. To help answer the question, the author describes two relatively low-cost, rapid, qualitative studies in applied medical anthropology in Swaziland and in the Palestinian Territories. Although random sample surveys have become the gold standard for most policy makers dealing with KAP (knowledge, attitudes, and practices) data, qualitative research can form the basis of policy or program decisions under certain conditions.
Using Electronic Scanning Forms for Data Entry
Authors: Weller Susan C. , Baer Roberta D.
Published: April 2009

This article describes a technique for data entry of information obtained from interviews and questionnaires. Often, investigators have someone type information into an electronic computer database. This article describes the use of electronic scanning forms for data entry. Forms and equipment used for grading examinations may be used to record responses from questionnaires. This method of data entry is compatible with field research and can be quicker than hand entry of data.
A Case in Case Study Methodology
Authors: Meyer Christine Benedichte
Published: April 2009

The purpose of this article is to provide a comprehensive view of the case study process from the researcher's perspective, emphasizing methodological considerations. As opposed to other qualitative or quantitative research strategies, such as grounded theory or surveys, there are virtually no specific requirements guiding case research. This is both the strength and the weakness of this approach. It is a strength because it allows tailoring the design and data collection procedures to the research questions. On the other hand, this approach has resulted in many poor case studies, leaving it open to criticism, especially from the quantitative field of research. This article argues that there is a particular need in case studies to be explicit about the methodological choices one makes. This implies discussing the wide range of decisions concerned with design requirements, data collection procedures, data analysis, and validity and reliability. The approach here is to illustrate these decisions through a particular case study of two mergers in the financial industry in Norway.
Consensus Analysis for the Measurement and Validation of Personality Traits
Authors: Webster Cynthia M. , Iannucci Anita L. , Romney A. Kimball
Published: April 2009

The authors apply the cultural consensus model to the domain of personality and investigate (1) the level of consensus among informants' judgments on two traits, sociability and responsibility, and (2) the extent to which their judgments are veridical in that they measure differences among people that correspond to independent and external criteria. Two scales, responsibility and sociability from the California Personality Inventory (CPI) and the Eysenck Personality Questionnaire (EPQ) extraversion scale, were the external criteria used. Results show that informants exhibit consistent consensus in judging both traits for people they know. Similar to previous studies, informants tended to overrate rather than underrate themselves. Personality test scores in part support the validity of the peer ranking results. The responsibility consensus ranking and the CPI responsibility scale showed moderate association, whereas the associations between the sociability consensus ranking and the EPQ extraversion scale were moderate to weak. There was at best a weak association between the sociability consensus ranking and the CPI sociability scale.
When Recording Is Impossible
Authors: Werner Oswald
Published: April 2009

Whenever possible, ethnographers should record conversation (interviews) with the “natives.” This Short Take deals with mnemonic procedures that an ethnographer can use when recording is impossible for external reasons. The author recommends two methods: (1) memory training and (2) recalling of the interview “in your mind’s eye” three times, each with increasing recall of detail.
Complexity Theory: An Exploration and Overview Based on John Holland’s Work
Authors: Agar Michael
Published: April 2009

Complexity theory, developed primarily at the Santa Fe Institute in the 1980s, attracts increasing attention from social researchers. Complexity departs from the tradition of static linear models to focus on nonlinear dynamic systems, difficult to predict, with emergent properties not reducible to their elements. The author is currently working on a project to explain heroin trends. This article explores complexity theory, as reflected in the work of John Holland, to evaluate it as a candidate formal system after which to model this work. After reviewing some of the basic characteristics of the theory, an example is presented to evaluate the fit of theory to case and to outline the kinds of data necessary. At the metaphorical level, the evaluation is a positive one. How well the details of the formalism will fit the details of the case remains an open question.
Ivy League Athletic Performance
Authors: Kotlyarenko Dmitry , Ehrenberg Ronald G.
Published: April 2009

This article analyzes the determinants of undergraduate varsity athletic teams’ success in the Ivy League, a conference that prohibits athletic scholarships and holds its varsity athletes to high academic standards. The theoretical model suggests that the same factors that determine the enrollment decisions of all students who attend these institutions, namely, the institutions’ perceived academic quality and the generosity of their financial aid programs, should determine athletic performance success. In addition, the authors hypothesize that institutions whose athletes’ academic credentials are close to those of their class as a whole should have poorer records than those that accept scholar athletes whose credentials are relatively weaker as compared with their classmates. The empirical analyses use data for the 1981-1982 to 1996-1997 academic years on the number of male and female titles each institution in the conference won and the number of league games each won in men’s basketball, football, and hockey. The authors find strong support for the first two hypotheses and mixed support for the third.
The Bosman Case
Authors: Ericson Thomas
Published: April 2009

A league benefits from signing a contract that makes compensation compulsory to a team that loses its player on the expiry of his contract. This article analyzes the consequences of impeding such contracts between teams, as in the Bosman case, settled by the European Court of Justice in 1995. It is argued that smaller teams will sell their talent before the expiry of their contracts with the players to be able to bargain for a transfer fee from the recruiting team. Consequently, the quality of the leagues decreases.
The Demise of African American Baseball Leagues
Authors: Fort Rodney , Maxcy Joel
Published: April 2009

Organized African American baseball (AAB), the longest lived rival to Major League Baseball (MLB) in history, thrived from the 1920s through the early 1940s. Although integration in 1947 focused attention on MLB and the American experience, the impact on AAB receives only passing, somewhat wistful notice. From the economic perspective, the unabashed talent raiding by MLB killed AAB a couple of years after integration began. The authors show that AAB did pose an economic threat to MLB. Given this, the theory and history of MLB behavior toward rival leagues would have predicted actions by MLB to end the threat posed by AAB and a better economic outcome for at least some of the AAB owners and players than actually occurred. Although the former occurred, the latter never materialized for AAB. Competitive baseball was lost to countless thousands of fans throughout the South and Midwest, profitable businesses were lost to African American and White AAB team owners, and hundreds of African American players were denied a “big league” livelihood as the result of integration. The general perception is that integration was a positive thing but costly to many.
Efficient Markets? Don’t Bet on It
Authors: Osborne Evan
Published: April 2009

This article tests the efficient-markets hypothesis by looking at profits in National Football League (NFL) betting markets. The author tests whether successful betting strategies exist when points scored and allowed earlier in a season can outperform the betting line in predicting the margin of victory in NFL games and finds that profitable strategies exist. In addition, the author finds that over the course of a season, bettors do imperfectly incorporate information about team strength and that NFL victory margins are a highly variable process.
Is the Reward System in NASCAR Efficient?
Authors: Von Allmen Peter
Published: April 2009

This article provides an overview of compensation and reward schemes in professional automobile racing (NASCAR). Data from the 1998 and 1999 racing seasons show that although end-of-season rewards are highly nonlinear, individual races offer rewards that are more linear. Given that the general conditions for a rank order tournament do exist, this may indicate that the reward scheme is inefficient. Several hypotheses are suggested to explain why NASCAR would create such a reward structure. Vital to the investigation is the fact that teams attempt to maximize a profit function more complex than those in other individual sports. In addition, drivers may exhibit excessively aggressive behavior that would be exacerbated by nonlinear compensation, as described by Lazear. Analysis shows that the need to maintain sponsorship exposure, combined with drivers’ willingness to take risks (and the possible catastrophic result of negative outcomes), creates a competitive environment where winner-take-all would be inefficient.
Improvement by Spreading the Wealth
Authors: Yilmaz Mustafa R. , Chatterjee Sangit , Habibullah Mohamed
Published: April 2009

This study focuses on individual home run hitting in Major League Baseball. It is observed that the distribution of the rate of home run hitting is highly right skewed, but it is becoming discernibly less so over time. Frequencies of the lowest rates have been decreasing, whereas the frequencies of the higher rates are increasing. As a result, the mean rate as well as the standard deviation have both been increasing. On the other hand, relative variability as measured by the coefficient of variation has been decreasing over time. These observations lend support to an improvement in home run hitting in the sense that (a) more players are hitting a higher number of home runs, and (b) there is a more even distribution of home run hitting rates among players.
Baseball’s Blue Ribbon Economic Report
Authors: Eckard E. Woodrow
Published: April 2009

In July 2000, Major League Baseball published a report claiming a recent marked decline in competitive balance. The alleged cause is growing disparities in team revenues and payrolls driven ultimately by market size. Consequently, sweeping changes in the game’s economic structure are necessary, mainly composed of new labor market restrictions. The report, however, fails to present evidence of a decline in competitive balance or of a significant link between market size and winning. The present study seeks to provide the missing analysis. Although competitive balance might have declined in the American League (AL), it improved in the National League (NL). The difference is important, as both leagues are subject to the same governance structure—that is, the AL decline is likely due to idiosyncratic causes. Also, there is (at most) a weak relation between winning and market size that has not worsened in recent years.
Winner Take All in the NFL
Authors: Leeds Michael A. , Kowalewski Sandra
Published: April 2009

In an earlier paper, Kowalewski and Leeds showed that free agency and the salary cap brought profound changes to the level and nature of players’ salaries in the National Football League (NFL). Their study is limited, however, by the fact that—unlike most other professional athletes—football players are evaluated by position-specific statistics. The authors improve on their earlier work by performing quantile regressions on data for specific positions to show how free agency and the salary cap affected compensation. They show that the new bargaining regime greatly increased the reward to performance.
Differing Rates of Return to Performance
Authors: Rishe Patrick James
Published: April 2009

Recent academic literature has argued that there is no gender discrimination in professional golf and that the gender earnings gap is due to differences in average skill levels. This article examines whether the earnings gap between Professional Golf Association (PGA) and Senior Tour golfers is due to differences in average skill levels or the rates of return to these skills. Data used are from the 1999 professional golf season. OLS estimation, interaction terms, Oaxaca’s decomposition procedure, and gap analysis are employed to investigate this question. The results suggest that the primary source of the earnings gap between PGA and Senior Tour golfers is differences in the rates of return to performance. Although there are plausible explanations for why these differences in coefficients exist, the presence of age discrimination cannot be dismissed.
Home Run or Wild Pitch?
Authors: Baade Robert A. , Matheson Victor A.
Published: April 2009

Major League Baseball has rewarded cities that build new baseball stadiums with the chance to host the All-Star Game. Although the league asserts a significant boost to metropolitan economies due to the game, are these economic impact estimates published by the league credible? In two separate economic impact models, the authors find that All-Star Games since 1973 are actually associated with worse than expected economic performance in host cities.
The Pricing of a Round of Golf
Authors: Mulligan James G.
Published: April 2009

This article argues that the use of membership fees at shared facilities, such as private golf courses, is not per se evidence of inefficient pricing as implied by the club theory literature on variable usage. The author reconciles the inconsistency between the predictions of existing models and empirical evidence by accounting for members’ opportunity cost of time and the effect of congestion on members’ utility. In particular, this research shows that the simplified nature of congestion assumed in the literature ignores the positive externalities that members receive from a members-only club.
Economic Return on Schooling for Soccer Players
Authors: Barros Carlos Pestana
Published: April 2009

This article tests the relationship between earnings and schooling for male footballers of the Portuguese Football League, using data from a questionnaire carried out in the Lisbon area between January and April 2000. The author verifies that the sports market barely compensates the cost of education in accordance with the theory on the economic return on schooling; rather, it rewards talent in accordance with the theory on stardom. This finding is consistent with all currently available international evidence on the issue. Moreover, the article finds a significant positive association between earnings and professional status, union membership, the division in which the club competes, and the player’s performance.
Property Rights and Unilateral Player Transfers in a Multiconference Sports League
Authors: Marburger Daniel R.
Published: April 2009

According to the invariance hypothesis, the allocation of players in sports leagues is the same, regardless of who owns their property rights. However, when a player moves to a new team, the absolute quality of the new team increases while the absolute quality of the former team decreases. This implies that intraconference teams will be willing to bid more for players than interconference teams. However, the asking price for player sales to intraconference teams will be higher than for interconference clubs. If clubs own player property rights, the intraconference effects are built into the ask/bid price. When players own property rights, however, the effect of the transfer on the former club’s revenue stream is ignored. This suggests that free agency should result in a higher percentage of intraconference player transfers than player sales. Player sale data from 1964-1975 and free agency data between 1976-1992 reveal evidence consistent with theory.
Playing for Celebrity
Authors: Couldry Nick
Published: April 2009

If we are to understand series such as the first U.K. version of Big Brother as events, rather than just as texts or production processes, we need to draw on anthropological theory, for example, Dayan and Katz's theory of media events. This article develops an anthropologically informed argument about the status of Big Brother as event, its ambiguous claims to present social “reality,” and the connection of those claims with its other claim to offer “liveness” in a new web-enhanced form. These ambiguities can be traced not only in the discourse of the program but also in the discourses by producers and others that surrounded it, ambiguities that are ideological in the same way that “myth” was for Roland Barthes.
Big Brother
Authors: Hill Annette
Published: April 2009

In this article, the author focuses on Big Brother in relation to audience attraction. I outline the context of factual entertainment and its audience, and the specific experience of watching Big Brother. Seen in relation to factual entertainment as a whole, Big Brother is one of the least popular examples of “documentary as diversion.” Seen in relation to gamedocs, Big Brother is one of the most popular examples of new factual entertainment. The author's research, which uses quantitative and qualitative audience studies, indicates that attraction to Big Brother is based on the social and performative aspects of the program. The focus on the degree of actuality, on real people's improvised performances in the program, leads to a particular viewing practice: audiences look for the moment of authenticity when real people are “really” themselves in an unreal environment. This, the author argues, is the popularity of the gamedoc, evident in its early incarnation, and writ large in Big Brother spin-offs and sub-sequent series.
Pyoderma Gangrenosum
Authors: Mani Venk
Published: April 2009

Pyoderma Gangrenosum is cutaneous manifestation of a systemic problem that should be systematically diagnosed and managed with care. When such lesions appear on legs, it is important to study and treat the systematic problem.
A Comparison of Plantar Pressure in Patients With Diabetic Foot Ulcers Using Different Hosiery
Authors: Blackwell Byron , Aldridge Roy , Jacob Shirley
Published: April 2009

Abnormally high plantar pressure has been associated with the development of foot ulcers in populations with diabetes. Improved foot care includes the use of hosiery (socks) as well appropriate footwear. In this study, the Parotec System ® , an in-shoe plantar pressure measurement device, was used to measure the plantar pressure of the forefoot of 21 participants. All patients were diagnosed with diabetes and were assessed while wearing a combination of either a diabetic sock, a dress sock, or no sock and the participant’s own shoe or slipper. There were no statistically significant differences between combinations of socks and footwear.
Optical Measurement of Tissue Oxygen Saturation
Authors: Harrison David K. , Habil Med
Published: April 2009

Advances in opto-electronic systems have meant that optical spectroscopy can now be used for noninvasive measurements in tissue in patients. A number of techniques have evolved over the last 15 years that make use of the characteristic differences in the absorption spectrum of deoxygenated and oxygenated hemoglobin to measure oxygen saturation. This article summarizes, in particular, those techniques that may prove to be applicable to measurements relating to lower extremity wounds. A short introduction is given about existing electrode methods before describing applications of near infrared and visible wavelength spectroscopy to measurements in tissue. The advantages and limitations of these methods are discussed. An example of an area where tissue spectroscopy is now in routine clinical use for tissue healing viability assessment is presented.
The Political Impact of New Information Sources and Technologies in Indonesia
Authors: Winters Jeffrey A.
Published: April 2009

This article focuses on the explosion of international media coverage of Indonesia and the role of the Internet as two major factors in the unfolding of Indonesian politics at home and abroad during the last years of the New Order. Both international media coverage of Indonesia and the Internet had their primary impact at the level of elite politics, with the effect on the remainder of society being highly mediated by the local elites and the domestic mass media. The Internet served not only as a source of information, but also as a tool for activism and coordination among an increasingly disenchanted opposition.
The Suharto Regime and Its Fall Through the Eyes of the Local Media
Authors: Gazali Effendi
Published: April 2009

The first part of this article elaborates on the content and media management dynamics in local newspapers and radio stations during the period leading up to the fall of the New Order in Indonesia. The latter part deals with the early reform period after the downfall of Suharto. In-depth interviews were conducted with editorial policy-makers of the newspapers and with various radio station staff members in four cities where media consumption and other data had rarely been documented. The findings in the first part reveal omnipresent political control at two levels — local and central government. Because of this control, the local media personnel acknowledge their limitations, but strove for as much freedom as possible within the system. The second part shows that in this historical context, changes are taking place in both agency and structure. Both parts support the thesis that there is an interplay between agency and structure as opposed to the instrumentalist and structuralist orthodoxies.
What Does Government Regulation Really Mean?
Authors: Wilson Michelle , Wilson Amy
Published: April 2009

The terminology used to describe healthcare's regulatory environment can be daunting and often confusing. Idioms such as accreditation, certification, registration, and licensure are often erroneously interchanged and used in the wrong context. While standardized language within individual states is an important first step, standardization would be even more effective if it were incorporated in every state for the regulation and licensure of all health professions. The lack of uniformity in language between different healthcare professions limits effective professional practice and mobility, as well as adding confusion to legislators, professionals, and the public. This article will define and analyze the close nexus between the terminology used in regulating the healthcare field and how these terms specifically apply to the profession of sonography.
Congenital Mesoblastic Nephroma
Authors: Celik Handan , Kefeli Mehmet , Tosun Migraci , Çetinkaya Mehmet B. , Alper Tayfun , Yildiz Levent
Published: April 2009

Congenital mesoblastic nephroma is a rare renal tumor of early infancy with a favorable outcome after complete surgical removal. It consists of a heterogeneous group of spindle cell tumors. Early and accurate prenatal diagnosis of the renal tumor may improve the outcome of affected pregnancies by implementing the best strategy for prenatal management and delivery. But detection of congenital mesoblastic nephroma in a fetus is rare. To the authors' knowledge, there are fewer than 30 reports of a prenatal diagnosis of a mesoblastic nephroma in the literature. This case describes the prenatal sonographic diagnosis of cellular congenital mesoblastic nephroma.
Hodgkin lymphoma in the Swiss HIV Cohort Study
Authors: Clifford Gary M. , Rickenbach Martin , Lise Mauro , Dal Maso Luigino , Battegay Manuel , Bohlius Julia , Boffi El Amari Emmanuelle , Karrer Urs , Jundt Gernot , Bordoni Andrea , Ess Silvia , Franceschi Silvia ,   for the Swiss HIV Cohort Study
Published: April 2009

Hodgkin lymphoma (HL) risk is elevated among persons infected with HIV (PHIV) and has been suggested to have increased in the era of combined antiretroviral therapy (cART). Among 14 606 PHIV followed more than 20 years in the Swiss HIV Cohort Study (SHCS), determinants of HL were investigated using 2 different approaches, namely, a cohort and nested case-control study, estimating hazard ratios (HRs) and matched odds ratios, respectively. Forty-seven incident HL cases occurred during 84 611 person-years of SHCS follow-up. HL risk was significantly higher among men having sex with men (HR vs intravenous drug users = 2.44, 95% confidence interval [CI], 1.13-5.24) but did not vary by calendar period (HR for 2002-2007 vs 1995 or earlier = 0.65, 95% CI, 0.29-1.44) or cART use (HR vs nonusers = 1.02, 95% CI, 0.53-1.94). HL risk tended to increase with declining CD4+ cell counts, but these differences were not significant. A lower CD4+/CD8+ ratio at SHCS enrollment or 1 to 2 years before HL diagnosis, however, was significantly associated with increased HL risk. In conclusion, HL risk does not appear to be increasing in recent years or among PHIV using cART in Switzerland, and there was no evidence that HL risk should be increased in the setting of improved immunity.
A Continuous-Time Approach to Robbins' Problem of Minimizing the Expected Rank
Authors: Bruss F. Thomas , Swan Yvik C.
Published: April 2009

Let X1, X2, …, Xn be independent random variables uniformly distributed on [0,1]. We observe these sequentially and have to stop on exactly one of them. No recall of preceding observations is permitted. What stopping rule minimizes the expected rank of the selected observation? What is the value of the expected rank (as a function of n) and what is the limit of this value when n goes to ∞? This full-information expected selected-rank problem is known as Robbins' problem of minimizing the expected rank, and its general solution is unknown. In this paper we provide an alternative approach to Robbins' problem. Our model is similar to that of Gnedin (2007). For this, we consider a continuous-time version of the problem in which the observations follow a Poisson arrival process on ℝ+ × [0,1] of homogeneous rate 1. Translating the previous optimal selection problem in this setting, we prove that, under reasonable assumptions, the corresponding value function w(t) is bounded and Lipschitz continuous. Our main result is that the limiting value of the Poisson embedded problem exists and is equal to that of Robbins' problem. We prove that w(t) is differentiable and also derive a differential equation for this function. Although we have not succeeded in using this equation to improve on bounds on the optimal limiting value, we argue that it has this potential.
State-Dependent Utility
Authors: Londoño Jaime A.
Published: April 2009

We propose a new approach to utilities in (state) complete markets that is consistent with state-dependent utilities. Full solutions of the optimal consumption and portfolio problem are obtained in a very general setting which includes several functional forms for utilities used in the current literature, and consider general restrictions on allowable wealths. As a secondary result, we obtain a suitable representation for straightforward numerical computations of the optimal consumption and investment strategies. In our model, utilities reflect the level of consumption satisfaction of flows of cash in future times as they are (uniquely) valued by the market when the economic agents are making their consumption and investment decisions. The theoretical framework used for the model is the one proposed in Londoño (2008). We develop the martingale methodology for the solution of the problem of optimal consumption and investment in this setting.
An Optimal Dividends Problem with a Terminal Value for Spectrally Negative Lévy Processes with a Completely Monotone Jump Density
Authors: Loeffen R. L.
Published: April 2009

We consider a modified version of the classical optimal dividends problem of de Finetti in which the objective function is altered by adding in an extra term which takes account of the ruin time of the risk process, the latter being modeled by a spectrally negative Lévy process. We show that, with the exception of a small class, a barrier strategy forms an optimal strategy under the condition that the Lévy measure has a completely monotone density. As a prerequisite for the proof, we show that, under the aforementioned condition on the Lévy measure, the q-scale function of the spectrally negative Lévy process has a derivative which is strictly log-convex.
Bounds for the Ruin Probability of a Discrete-Time Risk Process
Authors: Diasparra Maikol A. , Romera Rosario
Published: April 2009

We consider a discrete-time risk process driven by proportional reinsurance and an interest rate process. We assume that the interest rate process behaves as a Markov chain. To reduce the risk of ruin, we may reinsure a part or even all of the reserve. Recursive and integral equations for ruin probabilities are given. Generalized Lundberg inequalities for the ruin probabilities are derived given a stationary policy. To illustrate these results, a numerical example is included.
Exponential Random Graphs as Models of Overlay Networks
Authors: Draief M. , Ganesh A. , Massoulié L.
Published: April 2009

In this paper we give an analytic solution for graphs withnnodes andE=cnlognedges for which the probability of obtaining a given graphGisµn(G) = exp (-β∑i=1ndi2), wherediis the degree of nodei. We describe how this model appears in the context of load balancing in communication networks, namely peer-to-peer overlays. We then analyse the degree distribution of such graphs and show that the degrees are concentrated around their mean value. Finally, we derive asymptotic results for the number of edges crossing a graph cut and use these results (i) to compute the graph expansion and conductance, and (ii) to analyse the graph resilience to random failures.
The APC/C E3 ligase remains active in most post-mitoticArabidopsiscells and is required for proper vasculature development and organization
Authors: Marrocco Katia , Thomann Alexis , Parmentier Yves , Genschik Pascal , Criqui Marie Claire
Published: April 2009

Selective protein degradation via the ubiquitin-26S proteasome is a major mechanism underlying DNA replication and cell division in all eukaryotes. In particular, the APC/C (anaphase promoting complex or cyclosome) is a master ubiquitin protein ligase (E3) that targets PDS1/SECURIN and cyclin B for degradation allowing sister chromatid separation and exit from mitosis,respectively. Interestingly, it has been found that the APC/C remains active in differentiated neurons in which the E3 ligase regulates axon growth,neuronal survival and synaptic functions. However, despite these recent findings, the role of APC/C in differentiated cells and the regulation of its activity beyond cell division is still poorly understood. Here, we investigate the activity and function of APC/C in the model plant Arabidopsis thaliana. We used cyclin reporter constructs to follow APC/C activity during plant development and found that this E3 ligase remains active in most post-mitotic plant cells. Strikingly, hypomorphic mutant lines, in which the APC/C activity is reduced, exhibited several developmental abnormalities,including defects in cotyledon vein patterning and internode elongation leading to a characteristic broomhead-like phenotype. Histological analyses revealed an increased amount of vascular tissue, most notably xylem and lignified sclerenchyma, indicating a role for APC/C in plant vasculature development and organization.
Adhesion signaling – crosstalk between integrins, Src and Rho
Authors: Huveneers Stephan , Danen Erik H. J.
Published: April 2009

Interactions between cells and the extracellular matrix coordinate signaling pathways that control various aspects of cellular behavior. Integrins sense the physical properties of the extracellular matrix and organize the cytoskeleton accordingly. In turn, this modulates signaling pathways that are triggered by various other transmembrane receptors and augments the cellular response to growth factors. Over the past years, it has become clear that there is extensive crosstalk between integrins, Src-family kinases and Rho-family GTPases at the heart of such adhesion signaling. In this Commentary, we discuss recent advances in our understanding of the dynamic regulation of the molecular connections between these three protein families. We also discuss how this signaling network can regulate a range of cellular processes that are important for normal tissue function and disease, including cell adhesion, spreading, migration and mechanotransduction.
Knockout of GARPs and the β-subunit of the rod cGMP-gated channel disrupts disk morphogenesis and rod outer segment structural integrity
Authors: Zhang Youwen , Molday Laurie L. , Molday Robert S. , Sarfare Shanta S. , Woodruff Michael L. , Fain Gordon L. , Kraft Timothy W. , Pittler Steven J.
Published: April 2009

Ion flow into the rod photoreceptor outer segment (ROS) is regulated by a member of the cyclic-nucleotide-gated cation-channel family; this channel consists of two subunit types, α and β. In the rod cells, the Cngb1 locus encodes the channel β-subunit and two related glutamic-acid-rich proteins (GARPs). Despite intensive research, it is still unclear why the β-subunit and GARPs are coexpressed and what function these proteins serve. We hypothesized a role for the proteins in the maintenance of ROS structural integrity. To test this hypothesis, we created a Cngb1 5′-knockout photoreceptor null (Cngb1-X1). Morphologically, ROSs were shorter and, in most rods that were examined, some disks were misaligned, misshapen and abnormally elongated at periods when stratification was still apparent and degeneration was limited. Additionally, a marked reduction in the level of channel α-subunit, guanylate cyclase I (GC1) and ATP-binding cassette transporter (ABCA4) was observed without affecting levels of other ROS proteins, consistent with a requirement for the β-subunit in channel assembly or targeting of select proteins to ROS. Remarkably, phototransduction still occurred when only trace levels of homomeric α-subunit channels were present, although rod sensitivity and response amplitude were both substantially reduced. Our results demonstrate that the β-subunit and GARPs are necessary not only to maintain ROS structural integrity but also for normal disk morphogenesis, and that the β-subunit is required for normal light sensitivity of the rods.
Heterodimerization controls localization of Duox-DuoxA NADPH oxidases in airway cells
Authors: Luxen Sylvia , Noack Deborah , Frausto Monika , Davanture Suzel , Torbett Bruce E. , Knaus Ulla G.
Published: April 2009

Duox NADPH oxidases generate hydrogen peroxide at the air-liquid interface of the respiratory tract and at apical membranes of thyroid follicular cells. Inactivating mutations of Duox2 have been linked to congenital hypothyroidism, and epigenetic silencing of Duox is frequently observed in lung cancer. To study Duox regulation by maturation factors in detail, its association with these factors, differential use of subunits and localization was analyzed in a lung cancer cell line and undifferentiated or polarized lung epithelial cells. We show here that Duox proteins form functional heterodimers with their respective DuoxA subunits, in close analogy to the phagocyte NADPH oxidase. Characterization of novel DuoxA1 isoforms and mispaired Duox-DuoxA complexes revealed that heterodimerization is a prerequisite for reactive oxygen species production. Functional Duox1 and Duox2 localize to the leading edge of migrating cells, augmenting motility and wound healing. DuoxA subunits are responsible for targeting functional oxidases to distinct cellular compartments in lung epithelial cells, including Duox2 expression in ciliated cells in an ex vivo differentiated lung epithelium. As these locations probably define signaling specificity of Duox1 versus Duox2, these findings will facilitate monitoring Duox isoform expression in lung disease, a first step for early screening procedures and rational drug development.
Continuity of Health Care and the Pharmacist: Let's Keep It Simple
Authors: (Mick) Murray Michael D
Published: April 2009

Pharmacists are a cornerstone of quality medication management. High-quality continuity of care involves patient-centered medication therapy management, which could be bolstered for 26 million Part D Medicare beneficiaries. Yet, many patients do not receive sufficient instruction about their prescription medications. Patient-centered aspects are important because of the heterogeneity in patient types and severity of disease, varying treatment requirements, lifestyle factors, and differences in health literacy. Although time constraints for all health professionals are apparent, a simple but crucial contribution by pharmacists to the continuity of care is to increase the emphasis on patient-centered medication instruction.