bluuebunny/crossref_metadata_2025 huggingface dataset:
Selection of new health technologies for assessment aimed at informing decision making: A survey among horizon scanning systems
Authors: Douw Karla , Vondeling Hindrik
Published: April 2008

Objectives:Uncertainty is pervasive in decision making on new health technologies; therefore, some countries have put systems in place to support decision makers with timely information. An important, but as yet undocumented, determinant of the potential value for decision making of these so-called horizon scanning systems (HSSs) is how the most significant health technologies are selected.

Methods:All thirteen member organizations of EuroScan, a collaborative network for HSSs, were surveyed and interviewed on how they prioritize technologies for assessment.

Results:The majority of HSSs directly serves a customer. Some customers actively request early assessments of new health technologies, thereby diminishing the need for priority setting for the HSSs. All systems express a concern to miss an important technology and/or to select an unimportant technology. Almost all HSSs use explicit selection criteria, but these criteria hardly ever are operationalized. The number of criteria used varies, but costs and health benefit of the technology are always taken into account. The process of reaching a final decision is implicit, undocumented in all but one system, and is based on agreement by consensus.

Conclusions:The process of making the final decision on which technologies to assess can be improved by applying existing criteria more consistently and transparently. Current practice does not safeguard against missing an important technology. This finding is probably most important to act upon for systems with customers that do not actively request assessment of specific technologies.
Diffusion of diagnostic medical devices and policy implications for India
Authors: Mahal Ajay , Varshney Anil , Taman Srinivas
Published: April 2008

Objectives:This study describes the diffusion of advanced diagnostic devices in India and assess implications for efficiency in resource use and equity.

Methods:Commodity-level import statistics, household survey data, and interviews with medical device sellers are used to assess the spread of diagnostic devices. Published qualitative evidence, case studies of diagnostic service providers, and cross-country analyses are used to identify the reasons underlying the spread of medical devices in India. Case studies of public and private providers and data from 150 hospitals in one Indian state are used to assess efficiency in resource use and the distributive impacts of diagnostic devices.

Results:High-end medical device inflows rose during the 1990s, with both supply- and demand-side factors influencing this trend. Although our results suggest that the overall quantity of advanced diagnostics in India is not excessive, there is some evidence of inefficiency in public facilities and possibly unethical practices in private diagnostic facilities. The unequal geographical distribution of magnetic resonance imaging facilities, coupled with inefficient use of medical devices in public facilities suggests inequality in access.

Conclusions:The study points to major regulatory gaps and health system inefficiencies and suggests ways in which these gaps can be addressed.
Evaluation of the ambulatory and home care record: Agreement between self-reports and administrative data
Authors: Guerriere Denise N. , Ungar Wendy J. , Corey Mary , Croxford Ruth , Tranmer Jennifer E. , Tullis Elizabeth , Coyte Peter C.
Published: April 2008

Objectives:Although measuring the utilization of ambulatory and home-based healthcare resources is an essential component of economic analyses, very little methodological attention has been devoted to the development and evaluation of resource costing tools. This study evaluated a newly developed tool, the Ambulatory and Home Care Record (AHCR), which comprehensively evaluates costs incurred by the health system and care recipients and their unpaid caregivers.

Methods:The level of agreement between self-reports from 110 cystic fibrosis care recipients and administrative data was assessed for four categories of health services: home-based visits with healthcare professionals, ambulatory visits with healthcare professionals, laboratory and diagnostic tests, and prescription medications.

Results:Agreement between care recipients' reports on the AHCR and administrative data ranged from moderate (kappa=0.41; 95 percent confidence interval, 0.16–0.61) for physician specialist visits to perfect (kappa=1.0) for physiotherapy visits.

Conclusions:By evaluating and standardizing a resource and costing tool, such as the AHCR, economic evaluations may be improved and comparisons of the resource implications for different services and for diverse populations are possible.
Investigating patients' preferences for cardiac rehabilitation in Denmark
Authors: Kjær Trine , Gyrd-Hansen Dorte , Willaing Ingrid
Published: April 2008

Objectives:The objective of this study was to analyze preferences for activities comprised in comprehensive cardiac rehabilitation programs among former cardiac patients from three different hospitals in Copenhagen County, Denmark.

Methods:A discrete choice experiment was applied to elicit the preferences for the offer of participation in various cardiac rehabilitation program activities: smoking cessation course, physical exercise program, personal meetings with cardiac nurse, group meetings managed by cardiac nurses, and nutritional counseling guidance. The questionnaire was sent to 742 former cardiac patients. We had a response rate of 69 percent.

Results:We found that preferences differed with respect to gender and age and that the offer of participation in cardiac rehabilitation activities was not highly valued by older patients, in particular among older men.

Conclusions:The discrete choice experiment proved a valuable instrument for the measurement of preferences for cardiac rehabilitation. The study provides important information on patients' preferences for cardiac rehabilitation for healthcare professionals and decision makers.
Use of quality-adjusted life years for the estimation of effectiveness of health care: A systematic literature review
Authors: Räsänen Pirjo , Roine Eija , Sintonen Harri , Semberg-Konttinen Virpi , Ryynänen Olli-Pekka , Roine Risto
Published: April 2008

Objectives:The objectives of this study were to identify, in a systematic literature review, published studies having used quality-adjusted life years (QALYs) based on actual measurements of patients' health-related quality of life (HRQoL) and to determine which HRQoL instruments have been used to calculate QALYs. Furthermore, the aims were to characterize studies with regard to medical specialty, intervention studied, results obtained, quality, country of origin, QALY gain observed, and interpretation of results regarding cost-effectiveness.

Methods:Systematic searches of the literature were made using the MEDLINE, Embase, CINAHL, SCI, and Cochrane Library electronic databases. Initial screening of identified articles was based on abstracts read independently by two of the authors; full-text articles were again evaluated by two authors, who made the final decision on which articles should be included.

Results:The search identified 3,882 articles; 624 were obtained for closer review. Of the reviewed full-text articles, seventy reported QALYs based on actual before–after measurements using a valid HRQoL instrument. The most frequently used instrument was EuroQol HRQoL instrument (EQ-5D, 47.5 percent). Other instruments used were Health Utilities Index (HUI, 8.8 percent), the Rosser–Kind Index (6.3 percent), Quality of Well-Being (QWB, 6.3 percent), Short Form-6D (SF-6D, 5.0 percent), and 15D (2.5 percent). The rest (23.8 percent) used a direct valuation method: Time Trade-Off (10.0 percent), Standard Gamble (5.0 percent), visual analogue scale (5.0 percent), or rating scale (3.8 percent). The most frequently studied medical specialties were orthopedics (15.5 percent), pulmonary diseases (12.7 percent), and cardiology (9.9 percent). Ninety percent of the studies came from four countries: United Kingdom, United States, Canada, the Netherlands. Approximately half of the papers were methodologically high quality randomized trials. Forty-nine percent of the studied interventions were viewed by the authors of the original studies as being cost-effective; only 13 percent of interventions were deemed not to be cost-effective.

Conclusions:Although QALYs gained are considered an important measure of effectiveness of health care, the number of studies in which QALYs are based on actual measurements of patients' HRQoL is still fairly limited.
Importance of appropriateness of empiric antibiotic therapy on clinical outcomes in intra-abdominal infections
Authors: Baré Marisa , Castells Xavier , Garcia Angel , Riu Marta , Comas Mercè , Egea Maria José Gil
Published: April 2008

Objectives:The objective of this study is to describe the frequency of inappropriate empirical antibiotic therapy in secondary intra-abdominal infection and to identify the possible relationship between inappropriateness and some clinical outcomes.

Methods:A retrospective descriptive multicenter study was conducted using hospital secondary databases developed at two university hospitals located in northeast Spain. Participants were patients 18 years of age or older who were diagnosed with community-acquired intra-abdominal infections between January 1, 1998, and December 31, 2000, identified through computerized patient records using ICD-9 codes. Appropriateness of empirical treatment was defined according to the recommendations of the literature. The clinical outcome of each patient was classified as one of the following: (i) resolved with initial therapy, (ii) required second-line antibiotics, (iii) required re-operation, or (iv) in-hospital death. The Fisher's exact test or the Chi-squared test for categorical variables and thet-test or Mann–Whitney test for continuous variables were used for comparing groups. Conditional logistic and linear regression analyses were also applied.

Results:Of 376 cases, 51 cases (13.6 percent, 95 percent confidence interval, 10–17 percent) received inappropriate empirical antibiotic therapy according to the scientific literature. Inappropriate initial empirical treatment was significantly associated with the need for a second line of antibiotics (p<.001), although not with re-operation, mortality, or length of hospitalization.

Conclusions:Approximately 14 percent of the patients received inappropriate empirical antibiotic treatment. Worse clinical outcomes consistently were observed in the group of patients receiving inappropriate empirical treatment. The appropriateness of antibiotic treatment for a given infection, in light of the availability of clearly defined clinical guidelines is an easily evaluated aspect of the quality of care.
Managing urgent surgery as a process: Case study of a trauma center
Authors: Torkki Paulus Mikael , Alho Antti Ilmari , Peltokorpi Antti Veikko , Torkki Markus Ilmari , Kallio Pentti Ensio
Published: April 2008

Objectives:Industrial management principles could be used to improve the quality and efficiency of health care. In this study, we have evaluated the effects of a process management approach to trauma patient care. The major objective was to reduce the waiting times and increase the efficiency of the hospital.

Methods:Urgent surgery care was analyzed as an overall process. The process development followed the Plan-Do-Check-Act (PDCA) cycle and was based on statistical analysis of certain performance metrics. Data were collected from hospital databases and by personnel interviews. To develop the process, the anesthesia induction was performed outside the operating room, better process guidance was developed, and patient flow was reorganized. The transition time for these changes was 1 year (2002 to 2003).

Results:Waiting times decreased by 20.5 percent (p<.05), nonoperative times in the operating room were reduced by 23.1 percent (p<.001), and efficiency was increased by 9.7 percent (p<.001) after reengineering of the care process. Overtime hours decreased by 30.9 percent.

Conclusions:Managing urgent surgical care as a process can improve the productivity and quality of care without a need to increase personnel resources. The focus should be on reducing waiting times and waste times.
Noninferiority testing in cost-minimization studies: Practical issues concerning power analysis
Authors: Span Mark M. , TenVergert Elisabeth M. , van der Hilst Christian S. , Stolk Ronald P.
Published: April 2008

Objectives:In cost-minimization studies, it is important to establish noninferiority in the clinical effect of the treatments under investigation. The relationship between the proportion of patients reaching the end point in a study, equivalence limit (δ), and power is investigated in the context of cost-minimization studies with dichotomous clinical end points. Two formulations of the null-hypothesis, absolute and relative formulations of δ, will be explored.

Methods:Sensitivity analysis was performed, in which the effect of the predicted proportions and δ on the power in a noninferiority setting was investigated. The patterns found are discussed in terms of the practical relevance within the cost-minimization framework.

Results:Sensitivity analyses show different patterns of results for both null-hypotheses. The differences in these results originate from the way δ is expressed. By expressing δ as absolute difference, power grows quite fast when sample proportions are smaller than expected. In the case of a proportional δ at small sample proportions, the power to establish noninferiority remains low.

Conclusions:To obtain valid results from a cost-minimization study, care has to be taken to adapt the correct methodology for noninferiority testing in clinical outcomes. Defining δ in terms of absolute differences between treatments can lead to obscured results. Although conservative, the expression of δ as a proportion of the effectiveness of the treatment as usual is found to be closer to clinical practice. The inflated δ, resulting from smaller clinical effects than expected when absolute formulation is applied, thus can be avoided.
Author contacts for retrieval of data for a meta-analysis on exercise and diet restriction
Authors: Gibson Cheryl A. , Bailey Bruce Wayne , Carper Michael J. , LeCheminant James D. , Kirk Erik Paul , Huang Guoyuan , DuBose Katrina Drowatzky , Donnelly Joseph E.
Published: April 2008

Objectives: The mode of contact and response levels of authors who had been asked to provide missing or incomplete data for a systematic review on diet and exercise interventions for weight loss was examined.

Methods: We contacted authors by electronic mail, letter, or both. Survival analyses were performed with the Kaplan–Meier method to determine differences in the proportion of responders over time among the different modes of contact and to determine whether response rates differed between authors from the United States and those from other countries. Logistic regression was used to determine whether the number of items requested and publication date influenced the likelihood of response.

Results: Two hundred forty-one (39.9 percent) studies had missing or incomplete data (e.g., sample size, age, caloric restriction, exercise amount, and so on). We were unable to locate ninety-five authors (39.4 percent). Of the remaining authors, forty-six authors (31.5 percent) responded to information requests. Time to respond differed by contact method (p<.05): e-mail (3 ± 3 days), letter (27 ± 30 days), and both (13 ±12 days). Response rates from U.S. authors did not differ from those of other countries.

Conclusions: Our study suggests poor success in the acquisition of essential information. Given considerable time and resources, weight loss studies require improved reporting standards to minimize the relatively unsuccessful attempt to contact authors for important and necessary information.
THE BOOTSTRAP OF THE MEAN FOR DEPENDENT HETEROGENEOUS ARRAYS
Authors: Gonçalves Sílvia , White Halbert
Published: April 2008

Presently, conditions ensuring the validity of bootstrap methods
for the sample mean of (possibly heterogeneous) near epoch
dependent (NED) functions of mixing processes are unknown. Here
we establish the validity of the bootstrap in this context,
extending the applicability of bootstrap methods to a class
of processes broadly relevant for applications in economics
and finance. Our results apply to two block bootstrap methods:
the moving blocks bootstrap of Künsch (1989, Annals
of Statistics 17, 1217–1241) and Liu and Singh (1992,
in R. LePage & L. Billiard (eds.), Exploring the Limits
of the Bootstrap, 224–248) and the stationary bootstrap
of Politis and Romano (1994a, Journal of the American
Statistical Association 89, 1303–1313). In particular,
the consistency of the bootstrap variance estimator for the
sample mean is shown to be robust against heteroskedasticity
and dependence of unknown form. The first-order asymptotic validity
of the bootstrap approximation to the actual distribution of
the sample mean is also established in this heterogeneous NED
context.
NON- AND SEMIPARAMETRIC IDENTIFICATION OF SEASONAL NONLINEAR
AUTOREGRESSION MODELS
Authors: Yang Lijian , Tschernig Rolf
Published: April 2008

Non- or semiparametric estimation and lag selection methods are proposed
for three seasonal nonlinear autoregressive models of varying seasonal
flexibility. All procedures are based on either local constant or local
linear estimation. For the semiparametric models, after preliminary
estimation of the seasonal parameters, the function estimation and lag
selection are the same as nonparametric estimation and lag selection for
standard models. A Monte Carlo study demonstrates good performance of all
three methods. The semiparametric methods are applied to German real gross
national product and UK public investment data. For these series our
procedures provide evidence of nonlinear dynamics.
OBJECT LANGUAGE AND THE LANGUAGE SUBJECT: ON THE MEDIATING ROLE OF APPLIED LINGUISTICS
Authors: Widdowson Henry G.
Published: April 2008

As linguistics has extended its scope over the past thirty years from an exclusive concern with knowledge of the abstract code, what Chomsky referred to as Internalized (I) language, to a consideration of the way this knowledge is actualized in Externalized (E) language (Chomsky 1988), so it has inevitably gained in face validity as an area of inquiry relevant to practical life. A linguistics that deals with real, as distinct from ideal, speaker-listeners has a more obvious applicability to the problems real people actually have with language. Nevertheless, one cannot just assume a direct correspondence between the E externalized language the linguist describes and the E experienced language that is a reality for the user. The applicability of linguistic descriptions is a potential that has to be realized, and this is where applied linguistics comes in.
LSP IN NORTH AFRICA: STATUS, PROBLEMS AND, CHALLENGES
Authors: Daoud Mohamed
Published: April 2008

This chapter presents a survey of recent developments in teaching Languages for Specific Purposes (LSP) in North Africa and discusses current issues and future challenges. It devotes more space to ESP in this francophone environment given the greater demand for English, as opposed to other languages, and the more abundant ESP activity in terms of practice, research, and publications.
WRITING, LITERACY, AND APPLIED LINGUISTICS
Authors: Leki Ilona
Published: April 2008

The first charge to the contributors to this volume was to consider applied linguistics from the point of view of the subfield each of us represents. Such a formulation constructs writing and literacy research as subordinate to the super-ordinate domain of applied linguistics and this was not one that corresponded well with my own sense of my work in relation to applied linguistics. To investigate this issue further, I informally questioned other writing researchers about whether or not they consider themselves applied linguists and what they do to be applied linguistics.
SLA AND FIRST LANGUAGE ACQUISITION
Authors: Foster–Cohen Susan
Published: April 2008

In a brief article published some years ago (Foster-Cohen 1993), I suggested that fruitful collaboration between the fields of first and second language acquisition was underexploited. I also suggested that second language researchers were, in general, better at keeping themselves informed of developments in first language studies than first language researchers were at paying attention to second language issues. I think it fair to say that there are some signs this is changing. One is the now established existence of the journal Language Acquisition (Lawrence Erlbaum Associates), started in 1990, which publishes work in both first and second language acquisition with a view to understanding the nature of language acquisition in general. Its preference for papers that address issues in formal linguistic theory complements well Applied Psycholinguistics (Cambridge University Press), which has always published material relevant to both fields, but which also goes well beyond acquisition issues in its brief. A second factor seems to be a gentle but insistent re-examination of issues in bilingualism and a growing awareness that bilingual studies, second language studies, and first language studies overlap in important ways in the study of the bilingual individual. One key indicator of this shift is the appearance of a new journal Bilingualism: Language and Cognition (Cambridge University Press).
PSYCHOLINGUISTIC APPROACHES TO SLA
Authors: Segalowitz Norman , Lightbown Patsy M.
Published: April 2008

These are exciting times for research into the psychological processes underlying second language acquisition (SLA). In the 1970s, SLA emerged as a field of inquiry in its own right (Brown 1980), and in the 1980s, a number of different approaches to central questions in the field began to develop in parallel and in relative isolation (McLaughlin and Harrington 1990). In the 1990s, however, these different approaches began to confront one another directly. Now we are entering a period reminiscent, in many ways, of the intellectually turbulent times following the Chomskyan revolution (Chomsky 1957; 1965). Now, as then, researchers are debating basic premises of a science of mind, language, and learning. Some might complain, not entirely without reason, that we are still debating the same issues after 30–40 years. However, there are now new conceptual and research tools available to test hypotheses in ways previously thought impossible. Because of this, many psychologists believe there will soon be significant advancement on some SLA issues that have resisted closure for decades. We outline some of these developments and explore where the field may be heading. More than ever, it appears possible that psychological theory and SLA theory are converging on solutions to common issues.
LANGUAGE AND EDUCATION: RECONCEPTUALIZING EDUCATION AS DIALOGUE
Authors: Wells Gordon
Published: April 2008

In a review of this length, it is impossible to do justice to the many ways in which language is used in and about education. This article therefore presents only a personal view of some of the key issues. Chief among these, in my opinion, is the lack of a concensual view about the role that language plays in education and, in particular, about the importance of dialogue in learning and teaching. This state of affairs is hampering the many efforts that are being made to reform public education so that it can provide an equitable and effective induction of students into the ways of knowing and acting necessary for life in the post-industrial “information age”; it is also confusing, to say the least, for the teachers who have the responsibility for engaging students in the processes of knowledge construction. As will become apparent, I do not adopt an impartial stance, for I am convinced that students' interests are best served when they are actively involved in a dialogue in which their voices contribute, along with those of teachers and recognized “authorities,” to the continuing attempt to make sense of the human predicament and our relationship with our physical and social environment. The key question, then, is: How can this dialogue be extended?
LANGUAGE AND POLITICS
Authors: Chimombo Moira
Published: April 2008

This is an exciting time to be surveying the interrelationship between language and politics, both for political and linguistic reasons. The past decade, as everyone knows, has been witness to dramatic changes in the political map of the world, reflected most noticeably in the west in the fall of the Berlin Wall in November 1989, but also, more quietly in some cases, more violently in others, in countries physically and politically as far apart as South Africa and China. Moves toward democracy in many areas of the world coincided with or followed on the end of the Cold War. These moves came about due to a return to democracy of postcolonial states that had become totalitarian and the granting of independence to most of the few remaining colonies. Through such changes we have come to see that “the language of democracy was mobilised against regimes that, in however perverted a way, were speaking the language of Marxism and socialism” (Schwarzmantel 1998:183), colonialism, and other totalitarianisms. Between 1989 and 1994, although later in some countries, the vast majority of newly (re)democratized peoples experienced for the first time in their lives the opportunity to express freely their political voice in democratic general elections, reflecting a move from bullets to ballots that appeared to be a “virtual miracle” (Joseph 1998:3). Since 1994, in many places, the optimism has faded as the “illusory nature of [the new regimes'] democratic institutions and practices” has become evident (Joseph 1998:3). Even in the long–established democracies, a disturbing rise in hate speech leading to violence has served to emphasize that speech can, and often does, provoke action (Owen 1998), while in certain particularly troubled areas, discourse, especially media discourse, has even been linked to genocide (e.g., Lemarchand 1994).
RECENT DEVELOPMENTS IN LANGUAGE TESTING
Authors: Kunnan Antony John
Published: April 2008

In an earlier review for the Annual Review of Applied Linguistics, Douglas (1995) wrote, “the year 1990 represented a watershed in language testing” (p. 167). This decade, though by no means over, has taken the field even further in terms of theoretical and practical developments. A few examples should illustrate this point: For test theoreticians and researchers, models of communicative language ability have challenged the traditional skills–and–components models (Bachman 1990, Bachman and Palmer 1996); applications of Messick's (1989) expanded view of validation have balanced arguments previously made solely by measurement experts (Kunnan 1998a); discussions of policy and social considerations (McNamara 1998), fairness (Kunnan 1996; in press), critical language testing (Shohamy 1997a) and ethics and professionalism (Davies 1997a; 1997b) have added new beveled angles for debates; structural equation modeling has successfully asserted its role as useful quantitative methodology (Kunnan 1995; 1998b); and verbal protocol analysis has proved to be a viable qualitative methodology (Green 1997).
COMPUTER ADAPTIVE TESTING IN SECOND LANGUAGE CONTEXTS
Authors: Chalhoub–Deville Micheline , Deville Craig
Published: April 2008

The widespread accessibility to large, networked computer labs at educational sites and commercial testing centers, coupled with fast-paced advances in both computer technology and measurement theory, along with the availability of off-the-shelf software for test delivery, all help to make the computerized assessment of individuals more efficient and accurate than assessment using traditional paper-and-pencil (P&P) tests. Computer adaptive testing (CAT) is a form of computerized assessment that has achieved a strong foothold in licensure and certification testing and is finding greater application in many other areas as well, including education. A CAT differs from a straightforward, linear test in that an item(s) is selected for each test taker based on his/her performance on previous items. As such, assessment is tailored online to accommodate the test taker's estimated ability and confront the examinee with items that best measure that ability.
Locating Therapeutic Vaccines in Nineteenth-Century History
Authors: Gradmann Christoph
Published: April 2008

Argument

This essay places some therapeutic vaccines, including particularly the diphtheria antitoxin, into their larger historical context of the late nineteenth century. As industrially produced drugs, these vaccines ought to be seen in connection with the structural changes in medicine and pharmacology at the time. Given the spread of industrial culture and technology into the field of medicine and pharmacology, therapeutic vaccines can be understood as boundary objects that required and facilitated communication between industrialists, medical researchers, public health officials, and clinicians. It was in particular in relation to evaluation and testing for efficacy in animal models that these medicines became a model for twentieth-century medicine. In addition, these medicines came into being as a parallel invention in two very distinct local cultures of research: the Institut Pasteur in Paris and the Institut für Infektionskrankheiten in Berlin. While their local cultural origins were plainly visible, the medicines played an important role in the alignment of the methods and objects that took place in bacteriology research in France and Germany in the 1890s. This article assesses the two locally specific regimes for control in France and in Imperial Germany. In France the Institut Pasteur, building on earlier successful vaccines, enjoyed freedom from scrutinizing control. The tight and elaborate system of control that evolved in Imperial Germany is portrayed as being reliant on experiences that were drawn from the dramatic events that surrounded the launching of a first example of so-called “bacteriological medicine,” tuberculin, in 1890.
Enacting Cultural Boundaries in French and German Diphtheria Serum Research
Authors: Klöppel Ulrike
Published: April 2008

Argument

The experimental development of a therapeutic serum against diphtheria between 1891 and 1894 was characterized by a scientific competition that pitted Emil Behring from the Institute for Infectious Diseases in Berlin against Émile Roux and Elie Metschnikoff from the Pasteur Institute in Paris. In general, their competition can be regarded as an extension of the fundamental differences that separated the research schools of Robert Koch and Louis Pasteur. However, to characterize the competition for a diphtheria-serum as “national rivalry” fails to account adequately for the mutual adoption of experimental practices by the Berlin and Parisian protagonists, whose contributions to the development of a therapeutic serum were intertwined in complex ways. Nor can it be characterized as “cooperation,” given their fierce public disputes over scientific concepts and the fact that these disputes also shaped the peculiarities of the experimental procedures in Berlin and Paris. A close analysis reveals a complex picture of the dynamic interaction between the conceptual and experimental activities of Behring, Roux, and Metschnikoff – interaction that defined as well as bridged the “French” and “Prussian” experimental systems of diphtheria-serum research.
Packaging BCG: Standardizing an Anti-Tuberculosis Vaccine in Interwar Europe
Authors: Bonah Christian
Published: April 2008

Argument

Using the example of the anti-tuberculosis vaccine BCG during the 1920s and 1930s, this article asks how a labile laboratory-modified bacteria was transformed into a genuine standard vaccine packaged and commercialized as a pharmaceutical product. At the center of the analysis lies the notion of standardization inquiring why and how a local laboratory process with standard operating procedures (SOPs) reached its limits and was transformed when the product faced international distribution. Moving from Paul Ehrlich's initial technological notion ofWertbestimmungreferring to a practice physiologically testing the effects of ill-defined antitoxins, the concept of standardization is extended to pharmaceutical and economical meanings implying quality control for biological therapeutic agents produced by a variety of industrial entrepreneurs. Following the request for product uniformity, two ways to maintain levels of compatibility and commonality are depicted opposing SOPs and end-product control. Furthermore, standardization is understood as a spiral, never ending process where progressive transformation of the vaccine in its production and medical uses periodically recreated the necessity of standardization. Developments analyzed are thus understood as a stabilization process aligning laboratory settings, products, and practices with medical theories and practices through technical, bureaucratic, and organizational systems. A paradox of the analysis is that standardization as a historical phenomenon and moment in the history of drug development was initially linked to a problem of under-determination of what was to be standardized and to a knowledge gap before it could become a central concept for quality control.
WHEN ARE ON–OFF SOURCES SIS?: CONDITIONS AND APPLICATIONS
Authors: Vanichpun Sarut , Makowski Armand M.
Published: April 2008

Recent advances from the theory of multivariate stochastic orderings
can be used to formalize the “folk theorem” that positive
correlations lead to larger buffer levels at a discrete-time infinite
capacity multiplexer queue. In particular, it is known that if the
input traffic is larger than its independent version in the
supermodular (sm) ordering, then their corresponding buffer contents
are similarly ordered in the increasing convex (icx) ordering.

A
sufficient condition for the aforementioned sm comparison is the
stochastic increasingness in sequence (SIS) property of the input
traffic. In this article, we provide conditions for the stationary
on–off source to be SIS. We then use this result to find
conditions under which the superposition of independent on–off
sources and the M|G|∞ input model
are each sm greater than their respective independent version. Similar
but weaker SIS conditions are also obtained for renewal on–off
processes.
THE TIME-TO-EMPTY FOR TANDEM JACKSON NETWORKS
Authors: Zazanis Michael A.
Published: April 2008

We derive the distribution of the time-to-empty for an open tandem
Jackson network assuming that while in equilibrium at time 0, the
arrival stream is suddenly shut off. The analysis is based on analogous
results regarding the distribution of the time-to-empty for the
corresponding closed tandem Jackson network. The results obtained are
used in the analysis of a two-class tandem Jackson network with FIFO
discipline in which customers of the second class have negligible
service times.
LIKELIHOOD RATIO ORDERING OF THE INSPECTION PARADOX
Authors: Hu Taizhong , Zhuang Weiwei
Published: April 2008

In this article, some results on stochastic comparisons of the
inspection paradox introduced by Ross [Probability in the
Engineering and Informational Sciences 17: 47–51
(2003)] are established in the sense of the likelihood ratio
order.
HOW TO OBTAIN BATHTUB-SHAPED FAILURE RATE MODELS FROM NORMAL
MIXTURES
Authors: Navarro Jorge , Hernandez Pedro J.
Published: April 2008

We obtain some techniques to study the shape of reliability functions
(failure rate, mean residual life, etc.) by using the s-equilibrium
distribution of a renewal process defined by Fagiuoli and Pellerey
(Naval Res. Logist., 1993). We apply these techniques to study how to
obtain distributions with bathtub shaped failure rate (BFR) from
mixtures of two positive truncated normal distributions.
A NOTE ON THE INCREASING DIRECTIONALLY CONCAVE MONOTONICITY IN
QUEUES
Authors: Rolski Tomasz
Published: April 2008

In this article, we study comparison theorems for stochastic
functionals like V(∞;C) =
sup0≤t {M(t) −
C(t)} or V(T;C) =
sup0≤t≤T {M(t)
− C(t)}, where {M(t)} and
{C(t)} are two independent nondecreasing processes
with stationary increments. We will tacitly assume that the considered
stochastic functionals are proper random variables. We prove that
V(T;C′) ≤icxV(T;C) ≤icxV(T;C′′), where

and C′′(dt) = c(0) dt,
provided dC(t) is absolute continuous with density
c(t). Similarly, we show that
V(∞;C′) ≤icxV(∞;C) ≤icxV(∞;C′′). For proofs, we develop
the theory of the ≤idcv ordering defined by increasing
directionally concave functions. We apply the theory to
M/G/1 priority queues and
M/G/1 queues with positive and negative
customers.
OPTIMALITY OF FOUR-THRESHOLD POLICIES IN INVENTORY SYSTEMS WITH CUSTOMER RETURNS AND BORROWING/STORAGE OPTIONS
Authors: Feinberg Eugene A. , Lewis Mark E.
Published: April 2008

Consider a single-commodity inventory system in which the demand is modeled by a sequence of independent and identically distributed random variables that can take negative values. Such problems have been studied in the literature under the namecash managementand relate to the variations of the on-hand cash balances of financial institutions. The possibility of a negative demand also models product returns in inventory systems. This article studies a model in which, in addition to standard ordering and scrapping decisions seen in the cash management models, the decision-maker can borrow and store some inventory for one period of time. For problems with back orders, zero setup costs, and linear ordering, scrapping, borrowing, and storage costs, we show that an optimal policy has a simple four-threshold structure. These thresholds, in a nondecreasing order, are order-up-to, borrow-up-to, store-down-to, and scrap-down-to levels; that is, if the inventory position is too low, an optimal policy is to order up to a certain level and then borrow up to a higher level. Analogously, if the inventory position is too high, the optimal decision is to reduce the inventory to a certain point, after which one should store some of the inventory down to a lower threshold. This structure holds for the finite and infinite horizon discounted expected cost criteria and for the average cost per unit time criterion. We also provide sufficient conditions when the borrowing and storage options should not be used. In order to prove our results for average costs per unit time, we establish sufficient conditions when the optimality equations hold for a Markov decision process with an uncountable state space, noncompact action sets, and unbounded costs.
TRANSMISSION RATE CONTROL OVER RANDOMLY VARYING CHANNELS
Authors: Rajadhyaksha Gauresh , Borkar Vivek S.
Published: April 2008

The problem of controlling transmission rate over a randomly varying
channel is cast as a Markov decision process wherein the channel is
modeled as a Markov chain. The objective is to minimize a cost that
penalizes both buffer occupancy (equivalently, delay) and power. The
nature of the optimal policy is characterized using techniques adapted
from classical inventory control.
STOCHASTIC COMPARISONS OF GENERALIZED ORDER STATISTICS
Authors: Belzunce Félix , Mercader José-Angel , Ruiz José-María
Published: April 2008

In this article, we give several results on (multivariate and univariate) stochastic comparisons of generalized order statistics. We give conditions on the underlying distributions and the parameters on which the generalized order statistics are based, to obtain stochastic comparisons in the stochastic, dispersive, hazard rate, and likelihood ratio orders. Our results generalize some recent results for order statistics, record values, and generalized order statistics and provide some new results for other models such ask-record values and order statistics under multivariate imperfect repair.
COMPUTATIONAL ANALYSIS OF STATIONARY WAITING-TIME DISTRIBUTIONS OF
GIX/R/1 AND
GIX/D/1 QUEUES
Authors: Chaudhry Mohan L. , Choi Dae W. , Chae Kyung C.
Published: April 2008

In this article, we obtain, in a unified way, a closed-form analytic
expression, in terms of roots of the so-called characteristic equation
of the stationary waiting-time distribution for the
GIX/R/1 queue, where
R denotes the class of distributions whose
Laplace–Stieltjes transforms are rational functions (ratios of a
polynomial of degree at most n to a polynomial of degree
n). The analysis is not restricted to generalized
distributions with phases such as Coxian-n
(Cn) but also covers nonphase-type
distributions such as deterministic (D). In the latter case,
we get approximate results. Numerical results are presented only for
(1) the first two moments of waiting time and (2) the probability that
waiting time is zero. It is expected that the results obtained from the
present study should prove to be useful not only for practitioners but
also for queuing theorists who would like to test the accuracies of
inequalities, bounds, or approximations.
CONTROL POLICIES FOR INVENTORY SYSTEMS WITH PERISHABLE ITEMS:
OUTSOURCING AND URGENCY CLASSES
Authors: Bar-Lev Shaul K. , Perry David , Stadje Wolfgang
Published: April 2008

We consider control policies for perishable inventory systems with
random input whose purpose is to mitigate the effects of unavailability.
In the basic uncontrolled system, the arrival times of the items to be
stored and the ones of the demands for those items form independent
Poisson processes. The shelf lifetime of every item is finite and
deterministic. Every demand is for a single item and is satisfied by the
oldest item on the shelf, if available. The first controlled model
excludes the possibility of unsatisfied demands by introducing a second
source of fresh items that is completely reliable and delivers without
delay whenever the system becomes empty. In the second model, there is no
additional ordering option by outsourcing. However, to avoid the most
adverse effects of unavailability, the demands are classified into
different categories of urgency. An incoming demand is satisfied or not
according to its category and the current state of the system. For both
models, we determine the steady-state distribution of the virtual
outdating process, which is then used to derive the relevant cost
functionals: the steady-state distribution and expected value of the
number of items in the system, the rate of outdatings, as well as, for
model 1, the rate of special orders from the external source and, for
model 2, the rate of unsatisfied demands.
THE MX/D/c
BATCH ARRIVAL QUEUE
Authors: Franx Geert Jan
Published: April 2008

A surprisingly simple and explicit expression for the waiting time
distribution of the
MX/D/c batch
arrival queue is derived by a full probabilistic analysis, requiring
neither generating functions nor Laplace transforms. Unlike the solutions
known so far, this expression presents no numerical complications, not
even for high traffic intensities.
MULTIVARIATE DISPERSION ORDER AND THE NOTION OF COPULA APPLIED TO
THE MULTIVARIATE t-DISTRIBUTION
Authors: Arias-Nicolás J. P. , Fernández-Ponce J. M. , Luque-Calvo P. , Suárez-Llorens A.
Published: April 2008

We study the concept of multivariate dispersion order, defined as the
existence of an expansion function that maps a random vector to another
one, for multivariate distributions with the same dependence structure. As
a particular case, we can order the multivariate t-distribution
family in dispersion sense. Finally, we use these results in the problem
of detection and characterization of influential observations in
regression analysis. This problem can often be used to compare two
multivariate t-distributions.
SOME NEW BOUNDS FOR THE RENEWAL FUNCTION
Authors: Politis Konstadinos , Koutras Markos V.
Published: April 2008

In the literature, most of the bounds for the renewal function
U(x) corresponding to a lifetime distribution F
are given in terms of the first two moments of F only. The best
general upper bound of this type is the one given in Lorden (1970). In the
present article, we show that improved bounds can be obtained if one
exploits the specific form of the distribution F. We derive a
bound that improves upon Lorden's, at least on an interval
[0,a) with a ≤ ∞, and we give both
sufficient and necessary conditions for this improvement to hold uniformly
for x ≥ 0. Refined upper as well as lower bounds are given for
the case where F belongs to a class of distributions with
monotone aging or when the renewal density is monotone.
MOVE-FORWARD RULES AND f-SWAP RULES APPLIED TO A
COMMUNICATION PROBLEM
Authors: Chong King Sing , Lam Kin
Published: April 2008

In a communication network, one might attempt to route calls from an
origin to a destination through n paths that will be tried one by
one, each having a success probability pi
∈ (0,1), i = 1,2,…,n. The order of trying is
controlled by a routing table. The number of attempts made is defined as
the cost of the routing table. Move-forward self-organizing rules are
applied to the routing table and comparisons of expected equilibrium costs
are performed when p2 = p3 =
… = pn. Stationary distributions for a
subset of f-swap rules are obtained for general
pi's.
OPTIMIZATION AND OPTIMALITY OF (s,S) STOCHASTIC
INVENTORY SYSTEMS WITH NON-QUASICONVEX COSTS
Authors: Chen Frank Y. , Feng Y.
Published: April 2008

This article considers the optimization and optimality of
single-item/location, infinite-horizon, (s,S)
inventory models. Departing from the conventional approach, we do not
assume the loss function describing holding and shortage costs per period
to be quasiconvex. As the existing optimization algorithms have been
established on the condition of quasiconvexity, our goal in this article
is to develop a computational procedure for obtaining optimal
(s,S) policies for models with general loss functions.
Our algorithm is based on the parametric method commonly used in
fractional programming and is intuitive, exact, and efficient. Moreover,
this method allows us to extend the optimality of (s,S)
policies to a broader class of loss functions that can be
non-quasiconvex.
REGRESSION DEPENDENCE IN LATENT VARIABLE MODELS
Authors: Hu Taizhong , Chen Jing , Xie Chaode
Published: April 2008

Three new notions of positive dependence (positive regression
dependence, positive left-tail regression dependence, and positive
right-tail regression dependence) are studied in this article. Consider a
latent variable model where the manifest random variables
T1,T2,…,Tn
given latent random variable/vector
(Θ1,…,Θm) are conditional
independent. Conditions are identified under which
T1,…,Tn possesses
the new dependence notions for different types of latent variable model.
Applications of the results are also provided.
CORRECTION TO “DEPENDENCE, DISPERSIVENESS, AND MULTIVARIATE
HAZARD RATE ORDERING”
Authors: Khaledi Baha-Eldin , Kochar Subhash
Published: April 2008

In the article published last year, three inequalities should be in
the opposite direction.
ON THE OUTCOME OF A CASCADING FAILURE MODEL
Authors: Lefèvre Claude
Published: April 2008

This article is concerned with a loading-dependent model of cascading
failure proposed recently by Dobson, Carreras, and Newman [6]. The central problem is to determine the
distribution of the total number of initial components that will have
finally failed. A new approach based on a closed connection with epidemic
modeling is developed. This allows us to consider a more general failure
model in which the additional loads caused by successive failures are
arbitrarily fixed (instead of being constant as in [6]). The key mathematical tool is provided by the
partial joint distributions of order statistics for a sample of
independent uniform (0,1) random variables.