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Selected AbstractsGROWTH AND MEASUREMENT UNCERTAINTY IN AN UNREGULATED FISHERYNATURAL RESOURCE MODELING, Issue 3 2009ANNE B. JOHANNESEN Abstract Complete information is usually assumed in harvesting models of marine and terrestrial resources. In reality, however, complete information never exists. Fish and wildlife populations often fluctuate unpredictably in numbers, and measurement problems are frequent. In this paper, we analyze a time-discrete fishery model that distinguishes between uncertain natural growth and measurement error and in which exploitation takes place in an unregulated manner. Depending on the parameterization of the model and at which point of time uncertainty is resolved, it is shown that expected harvest under ecological uncertainty may be below or above that of the benchmark model with no uncertainty. On the other hand, when stock measurement is uncertain, expected harvest never exceeds the benchmark level. We also demonstrate that the harvesting profit, or rent, under uncertainty may be above that of the benchmark situation of complete information. In other words, less information may be beneficial for the fishermen. [source] Empowering Automated Trading in Multi-Agent EnvironmentsCOMPUTATIONAL INTELLIGENCE, Issue 4 2004David W. Ash Trading in the financial markets often requires that information be available in real time to be effectively processed. Furthermore, complete information is not always available about the reliability of data, or its timeliness,nevertheless, a decision must still be made about whether to trade or not. We propose a mechanism whereby different data sources are monitored, using Semantic Web facilities, by different agents, which communicate among each other to determine the presence of good trading opportunities. When a trading opportunity presents itself, the human traders are notified to determine whether or not to execute the trade. The Semantic Web, Web Services, and URML technologies are used to enable this mechanism. The human traders are notified of the trade at the optimal time so as not to either waste their resources or lose a good trading opportunity. We also have designed a rudimentary prototype system for simulating the interaction between the intelligent agents and the human beings, and show some results through experiments on this simulation for trading of the Chicago Board Options Exchange (CBOE) options. [source] No Smoking Gun: Findings From a National Survey of Office-Based Cosmetic Surgery Adverse Event ReportingDERMATOLOGIC SURGERY, Issue 11 2003Rajesh Balkrishnan PhD Background. Because of recent press reports of adverse outcomes, office-based cosmetic surgery has come under intense scrutiny and associated legislative regulatory action. Objective. To assess the safety of office-based cosmetic surgery through a national survey of state agencies that collect information on adverse patient outcomes. Methods. Medical boards or other responsible authorities were contacted in 48 states to obtain records on adverse outcomes from cosmetic surgery procedures performed in an office-based setting. Results. Five states were able to provide complete information regarding 13 cases of adverse outcomes that resulted from office-based cosmetic surgery procedures. Thirteen states had incomplete information or were unable to provide information. The remaining states reported no adverse outcomes. Information collected by state agencies varies greatly and is inadequate to define the safety of office-based cosmetic surgery practice. Conclusions. The need to regulate physician office surgery on the basis of hospital privileges and office certification is not supported by current data. Mandatory reporting of adverse outcomes from office-based surgery is warranted to identify modifiable risk factors and to reduce the risk of adverse outcomes. [source] Incomplete Adoption of a Superior InnovationECONOMICA, Issue 268 2000Harvey E. Lapan We consider a model in which an innovating monopolist of a technologically superior intermediate input must sell this product to final output producers. Prior research shows that, with complete information, the monopolist's optimal strategy will lead to complete adoption of this technologically superior innovation. In this article we show that, when the price of some competitively supplied input used in the final product market is endogenous and is altered by adoption of the innovation, then the optimal pricing strategy of the monopolist may lead to incomplete innovation. Thus, the standard result of complete adoption of the superior technology is partly attributable to the partial equilibrium nature of prior models. [source] Differences in the measured alcohol content of drinks between black, white and Hispanic men and women in a US national sampleADDICTION, Issue 9 2009William C. Kerr ABSTRACT Aims To measure and describe drink alcohol content differences between Hispanic, non-Hispanic white and non-Hispanic black men and women in the United States. Design A telephone survey re-interview of 397 respondents who participated originally in the 2005 National Alcohol Survey, of whom 306 provided complete information on home drinks. Setting United States. Participants Adults aged 18 years and older from across the United States. Measurements Direct measurement by respondents of simulated drink pours in respondents' own glassware using a provided beaker and reported beverage brands were used to calculate drink alcohol content. Findings Black men were found to have the largest overall mean drink alcohol content at 0.79 oz (23 ml) of alcohol. This was significantly larger than the mean for white men or for black women and added 30% to black men's monthly alcohol intake when applied to their reported number of drinks. Spirits drinks were found to be particularly large for men. Multivariate models indicated that drink alcohol content differences are attributable more to income and family structure differences than to unmeasured cultural factors tied to race or ethnicity per se. Models predicting alcohol-related consequences and dependence indicate that adjusting drink alcohol content improves model fit and reduces differences between race/ethnicity defined groups. Conclusions Differences in drink alcohol content by gender, race/ethnicity and beverage type choice should be considered in comparisons of drinking patterns and alcohol-related outcomes. Observed differences can be explained partially by measured characteristics regarding family structure and income. [source] Weathering and aging of 2,4,6-trinitrotoluene in soil increases toxicity to potworm Enchytraeus crypticusENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2005Roman G. Kuperman Abstract Energetic materials are employed in a wide range of commercial and military activities and often are released into the environment. Scientifically based ecological soil-screening levels (Eco-SSLs) are needed to identify contaminant explosive levels in soil that present an acceptable ecological risk. Insufficient information for 2,4,6-trinitrotoluene (TNT) to generate Eco-SSLs for soil invertebrates necessitated toxicity testing. We adapted the standardized Enchytraeid Reproduction Test and selected Enchytraeus crypticus for these studies. Tests were conducted in Sassafras sandy loam soil, which supports relatively high bioavailability of TNT. Weathering and aging procedures for TNT amended to test soil were incorporated into the study design to produce toxicity data that better reflect the soil exposure conditions in the field compared with toxicity in freshly amended soils. This included exposing hydrated TNT-amended soils in open glass containers in the greenhouse to alternating wetting and drying cycles. Definitive tests showed that toxicity for E. crypticus adult survival and juvenile production was increased significantly in weathered and aged soil treatments compared with toxicity in freshly amended soil based on 95% confidence intervals. The median effect concentration and 20% effective concentration for reproduction were 98 and 77 mg/kg, respectively, for TNT freshly amended into soil and 48 and 37 mg/kg, respectively, for weathered and aged TNT soil treatments. These findings of increased toxicity to E. crypticus in weathered and aged TNT soil treatments compared with exposures in freshly amended soils show that future investigations should include a weathering and aging component to generate toxicity data that provide more complete information on ecotoxicological effects of energetic contaminants in soil. [source] Occupational exposure to methyl tertiary butyl ether in relation to key health symptom prevalence: the effect of measurement error correctionENVIRONMETRICS, Issue 6 2003Aparna P. Keshaviah Abstract In 1995, White et al. reported that methyl tertiary butyl ether (MTBE), an oxygenate added to gasoline, was significantly associated with key health symptoms, including headaches, eye irritation, and burning of the nose and throat, among 44 people occupationally exposed to the compound and for whom serum MTBE measurements were available (odds ratio (OR),=,8.9, 95% CI,=,[1.2, 75.6]). However, these serum MTBE measurements were available for only 29 per cent of the 150 subjects enrolled. Around the same time, Mannino et al. conducted a similar study among individuals occupationally exposed to low levels of MTBE and did not find a significant association between exposure to MTBE and the presence of one or more key health symptoms among the 264 study participants (OR,=,0.60, 95% CI,=,[0.3, 1.21]). In this article, we evaluate the effect of MTBE on the prevalence of key health symptoms by applying a regression calibration method to White et al.'s and Mannino et al.'s data. Unlike White et al., who classified exposure using actual MTBE levels among a subset of the participants, and Mannino et al., who classified exposure based on job category among all participants, we use all of the available data to obtain an estimate of the effect of MTBE in units of serum concentration, adjusted for measurement error due to using job category instead of measured exposure. After adjusting for age, gender and smoking status, MTBE exposure was found to be significantly associated with a 50 per cent increase in the prevalence of one or more key health symptoms per order of magnitude increase in blood concentration on the log10 scale, using data from the 409 study participants with complete information on the covariates (95% CI,=,[1.00, 2.25]). Simulation results indicated that under conditions similar to those observed in these data, the estimator is unbiased and has a coverage probability close to the nominal value. The methodology illustrated in this article is advantageous because all of the available data were used in the analysis, obtaining a more precise estimate of exposure effect on health outcome, and the estimate is adjusted for measurement error due to using job category instead of measured exposure. Copyright © 2003 John Wiley & Sons, Ltd. [source] ALS patients request more information about cognitive symptomsEUROPEAN JOURNAL OF NEUROLOGY, Issue 5 2008P. Wicks Background and purpose:, Once thought to impact only voluntary motor function, ALS/Motor neuron disease (MND) is now seen as a multi-system disorder in which a minority of patients experience mild cognitive dysfunction or frontotemporal dementia. Despite clinical guidelines advocating supplying complete information to patients, educational materials on ALS often state that the mind is unaffected. We sought to establish how much patients and caregivers understand about ALS, what they have been told to expect by their physician, and if they would have appreciated more complete information. Methods:, A two-part survey was administered online. An ,ALS quiz' gauged participants' knowledge of physical and psychological aspects of ALS. A second questionnaire assessed which symptoms patients had discussed with their clinician and explored patients' desire to receive information on psychological effects. Results:, A total of 247 ALS patients and 87 caregivers participated. Participants knew less about psychological symptoms than physical ones (72% correct responses versus 82%; paired t(333) = ,5.04, P < 0.001). Patients commonly reported being told by their doctor about physical symptoms such as problems walking (85%) or stiffness/cramps (74%) but not psychological issues like emotional lability (46%) or cognitive change (11%). The majority of patients (62%) and carers (71%) indicated a desire to be informed that cognitive change or dementia might occur. Conclusion:, ALS is a multi-system disorder. However, despite a desire for more information from patients and their carers, healthcare professionals continue to primarily address only the physical consequences of the disease. [source] An Analysis of Tenure and House Structure Type by Household CompositionFAMILY & CONSUMER SCIENCES RESEARCH JOURNAL, Issue 2 2007Stephanie E. Vanderford This study examined the relation of household composition and characteristics with each of two variables, tenure status and structural type of residence. Past research related to tenure status has considered household composition and characteristics in a limited manner, and very little empirical work has addressed the relations of those variables with house structure type. The three structure types assessed were manufactured housing, multifamily site-built homes, and single-family site-built homes. The authors extended past research by considering more complicated household compositions and also identified the importance of knowing more complete information about all the residents of a home to understand both tenure and house structure type. Family composition and the presence of extended family members, an unmarried partner, and other unrelated individuals all explained di ferences in tenure and house structure type. The findings suggest the significance of family and household characteristics when understanding variations in tenure and house structure type. [source] An Empirical Taxonomy of Hospital Governing Board RolesHEALTH SERVICES RESEARCH, Issue 4 2008Shoou-Yih D. Lee Objective. To develop a taxonomy of governing board roles in U.S. hospitals. Data Sources. 2005 AHA Hospital Governance Survey, 2004 AHA Annual Survey of Hospitals, and Area Resource File. Study Design. A governing board taxonomy was developed using cluster analysis. Results were validated and reviewed by industry experts. Differences in hospital and environmental characteristics across clusters were examined. Data Extraction Methods. One-thousand three-hundred thirty-four hospitals with complete information on the study variables were included in the analysis. Principal Findings. Five distinct clusters of hospital governing boards were identified. Statistical tests showed that the five clusters had high internal reliability and high internal validity. Statistically significant differences in hospital and environmental conditions were found among clusters. Conclusions. The developed taxonomy provides policy makers, health care executives, and researchers a useful way to describe and understand hospital governing board roles. The taxonomy may also facilitate valid and systematic assessment of governance performance. Further, the taxonomy could be used as a framework for governing boards themselves to identify areas for improvement and direction for change. [source] Access to Health Care Services for the Disabled ElderlyHEALTH SERVICES RESEARCH, Issue 3p1 2006Donald H. Taylor Jr. Objective. To determine whether difficulty walking and the strategies persons use to compensate for this deficit influenced downstream Medicare expenditures. Data Source. Secondary data analysis of Medicare claims data (1999,2000) for age-eligible Medicare beneficiaries (N=4,997) responding to the community portion of the 1999 National Long Term Care Survey (NLTCS). Study Design. Longitudinal cohort study. Walking difficulty and compensatory strategy were measured at the 1999 NLTCS, and used to predict health care use as measured in Medicare claims data from the survey date through year-end 2000. Data Extraction. Respondents to the 1999 community NLTCS with complete information on key explanatory variables (walking difficulty and compensatory strategy) were linked with Medicare claims to define outcome variables (health care use and cost). Principal Findings. Persons who reported it was very difficult to walk had more downstream home health visits (1.1/month, p<.001), but fewer outpatient physician visits (,0.16/month, p<.001) after controlling for overall disease burden. Those using a compensatory strategy for walking also had increased home health visits/month (0.55 for equipment, 1.0 for personal assistance, p<.001 for both) but did not have significantly reduced outpatient visits. Persons reporting difficulty walking had increased downstream Medicare costs ranging from $163 to $222/month (p<.001) depending upon how difficult walking was. Less than half of the persons who used equipment to adapt to walking difficulty had their difficulty fully compensated by the use of equipment. Persons using equipment that fully compensated their difficulty used around $300/month less in Medicare-financed costs compared with those with residual difficulty. Conclusions. Difficulty walking and use of compensatory strategies are correlated with the use of Medicare-financed services. The potential impact on the Medicare program is large, given how common such limitations are among the elderly. [source] A reexamination of corporate risks under shadow costs of incomplete informationINTERNATIONAL JOURNAL OF FINANCE & ECONOMICS, Issue 1 2001Mondher Bellalah G3; G31; G32; G33 Abstract The valuation of the firm and its assets has been done for a long time in the classic context of complete information. Several empirical tests of the main valuation methods reveal a divergence between theoretical prices and observed prices. These deviations might be explained by the standard assumptions of complete information. It is possible to introduce information uncertainty as done by Merton and by Bellalah in the reexamination of corporate risks in the presence of information costs. The concept of risk is useful in modelling the value of the firm and its business risk and in the definition of the required rates of return and the cost of capital of corporations. However, the main well-known results ignore information uncertainty as defined by Merton. Using the main results from the study of Modigliani and Miller and the implications of Merton's model, we give expressions for the cost of capital and the value of the firm's equity and debt in the presence of information costs. We reexamine the relationships between interrelated risks in the same context. We introduce information costs in the computation of the cost of capital and in the pricing of equity in an option framework. When there are no information costs, the main relationships reduce to the classic results in the literature. Copyright © 2001 John Wiley & Sons, Ltd. [source] Reaching consensus in multiagent decision makingINTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 3 2010Antonio Maturo A group decision making procedure, when developed in a dynamic context, grows from both an evolving knowledge base and the changes in the positions of the components, or experts, of the group. Agreement and compromise go with and drive the steps of the procedure. Let us consider the case that a committee of experts is constituted to take decisions about a subject of social interest. Usually the job ends if a majority of the members of the committee have not too different opinions about the last state of the decision. We intend to clarify the meaning of the statement "have not too different opinions," to define a structure for the concept of consensus. We assume that an external chairman, with complete information about the state of all the components of group, urges or invites decision makers to reach a consensus. The judgements of the experts are represented, in this framework, by points in a metric space, and the consensus is obtained by a dynamical construction of a maximal winning coalition contained in a ball with a fixed and suitably small diameter. This also allows us to deal with the concept of consensus in terms of algorithm. © 2010 Wiley Periodicals, Inc. [source] Which Providers Should Communicate Which Critical Information About a New Medication?JOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 3 2009Patient, Pharmacist, Physician Perspectives OBJECTIVES: To investigate older patient, pharmacist, and physician perspectives about what information is essential to impart to patients receiving new medication prescriptions and who should provide the information. DESIGN: Qualitative focus group discussions. SETTINGS: Senior centers, retail pharmacies, and primary care physician offices. PARTICIPANTS: Forty-two patients aged 65 and older, 13 pharmacists, and 17 physicians participated in eight focus groups. MEASUREMENT: Qualitative analysis of transcribed focus group interviews and consensus through iterative review by multidisciplinary auditors. RESULTS: Patient, pharmacist, and physician groups all affirmed the importance of discussing medication directions and side effects and said that physicians should educate about side effects and that pharmacists could adequately counsel about certain important issues. However, there was substantial disagreement between groups about which provider could communicate which critical elements of medication-related information. Some pharmacists felt that they were best equipped to discuss medication-related issues but acknowledged that many patients want physicians to do this. Physicians tended to believe that they should provide most new-medication education for patients. Patients had mixed preferences. Patients aged 80 and older listed fewer critical topics of discussion than younger patients. CONCLUSION: Patients, pharmacists, and physicians have incongruent beliefs about who should provide essential medication-related information. Differing expectations could lead to overlapping, inefficient efforts that result in communication deficiencies when patients receive a new medication. Collaborative efforts to ensure that patients receive complete information about new medications could be explored. [source] High individual repeatability and population differentiation in stable isotope ratios in winter-grown collared flycatcher Ficedula albicollis feathersJOURNAL OF AVIAN BIOLOGY, Issue 2 2009Mårten B. Hjernquist For migrants, we often lack complete information of their spatial distribution year round. Here, we used stable carbon, nitrogen and hydrogen isotope ratios extracted from feathers grown at the wintering sites of the long-distance migratory collared flycatcher Ficedula albicollis, to study how individuals from different breeding populations are distributed at the wintering sites. A sub-sample of birds was also sampled in two consecutive years to test for the repeatability of isotope ratios. Birds from the same breeding populations had more similar isotope ratios compared to birds from other nearby populations (10,100 km apart). Furthermore, isotope repeatability within individuals was high, implying that the observed pattern of isotope variation is consistent between years. We put forward two hypotheses for these patterns; 1) strong wintering site philopatry and migratory connectivity, suggesting that migratory connectivity may potentially be found on a much smaller spatial scale than previously considered, and 2) consistent interpopulation differentiation of feeding ecology at their wintering site. [source] A model of sequential effects in common pool resource dilemmasJOURNAL OF BEHAVIORAL DECISION MAKING, Issue 1 2002David V. Budescu Abstract Experimental games are often used as models of social dilemmas in which small groups of players have unrestricted access to, and share, a common and finite resource of desirable goods in the absence of any binding coordination mechanism. Examples are fishing, hunting, and use of computational facilities. Experimental studies of social dilemmas employ different protocols of play that differ from each other in terms of the information available to the players when they register their requests from the common resource. In this study we focus on the sequential protocol, where each participant has complete information about his or her position and the total requests of the previous movers, and the positional protocol, where each player only knows his or her position, but has no information about the other's requests. Previous research has found a robust position effect: individual requests are inversely related to the players' positions in the sequence with the first mover requesting most, and the last mover requesting the least. In an attempt to characterize the nature and intensity of the position effect, we developed and tested a descriptive model with one free (individual specific) parameter. The parameter is estimated from the players' requests under the positional protocol (i.e. in the absence of any information about the other's requests) and, as such, quantifies the social norm of ,advantage of the early mover'. In a range of cases examined, including different group sizes, resource pool sizes, and positions, the model predicted very accurately individuals' requests in the sequential protocol (with full information about position and others' requests). Copyright © 2002 John Wiley & Sons, Ltd. [source] Aggregation of ordinal and cardinal preferences: a framework based on distance functionsJOURNAL OF MULTI CRITERIA DECISION ANALYSIS, Issue 3-4 2008Jacinto González-Pachón Abstract In this paper a collective choice function (CCF), formulated within a p -metric distance function framework, is proposed as a generator of several compromise consensuses. Even though, the proposed CCF is not smooth, it is however demonstrated that it can be straightforwardly transformed into easily computable goal programming models. Finally, several cases of individual preferences aggregation are obtained by providing different interpretations of the CCF parameters: ordinal and complete information, ordinal and partial information and a cardinal case through ,pairwise' comparison matrices. Copyright © 2009 John Wiley & Sons, Ltd. [source] Regulated Firms with Transboundary Pollution: Does International Competition Improve Efficiency?JOURNAL OF PUBLIC ECONOMIC THEORY, Issue 3 2003Isabelle Péchoux We consider a model of strategic trade and environmental policies with transboundary pollution. A regulated monopoly produces in each country and emits pollution. Under complete information, opening borders leads to a reallocation of the production from the large country to the small one. Total production increases, leading to an increase in the total level of pollution. The creation of a common market sometimes leads to a deterioration of total welfare. Under asymmetric information, the international competition generated by the common market decreases the informational rents of the firms, thereby reinforcing the potential gain to open markets to international competition. [source] An example of the complementarity of laser-induced breakdown spectroscopy and Raman microscopy for wall painting pigments analysisJOURNAL OF RAMAN SPECTROSCOPY, Issue 7 2007Romain Bruder Abstract Laser-induced breakdown spectroscopy (LIBS) and Raman microscopy were used for the identification of pigments in wall painting. Raman spectroscopy, which provides the molecular ,fingerprint' of the compound, is nowadays widely used by the archaeometry community, especially for pigment analysis. LIBS, which provides the elementary composition of samples, is a rapid noncontact method, enabling layer-by-layer analysis through a precise laser ablation of the sample. This work deals with the behavior of pigments after a LIBS analysis, by trying to identify the compounds before and after the laser shot. Six commercial pigments prepared with the fresco technique were investigated: ultramarine blue, red lead, charcoal, a yellow and a red ochre, and a green earth. Raman spectra, acquired on the sample surface and in the crater induced by LIBS analysis, were compared. The results show that these pigments are well recognized after a LIBS measurement. The analysis of green earth illustrates that the combination of these two techniques gives complete information from a sample. Copyright © 2007 John Wiley & Sons, Ltd. [source] Knowledge and Behavior of Tourists to Manu National Park, Peru, in Relation to LeishmaniasisJOURNAL OF TRAVEL MEDICINE, Issue 4 2002Irmgard L. Bauer Background: Tourists have been infected with Leishmania braziliensis and the lack of appropriate travel information on the disease has been documented. The aim of this study was to describe the knowledge and behavior of tourists booked on a trip to Manu National Park in Peru in relation to leishmaniasis and its prevention. Methods: The clients of two tour operators in Cusco, Peru, represented the experimental and control group. The experimental group completed a questionnaire after the tour briefing the night before the trip and received the information leaflet. A second questionnaire was completed just before returning from the park. The clients in the control group did not receive the leaflet. Results: Three hundred and seventy-three questionnaire pairs were collected (173 experimental, 200 control). Only 24 (6%) of all participants claimed to have heard of leishmaniasis. Of the 92.5% of tourists who read the leaflet, 156 (97.5%) found it informative, although 50 (32.5%) wanted more information. It was suggested that the leaflet should be distributed by tour operators (56.9%), general practitioners/family doctors (49%), and travel agents (47.1%). There was no significant difference in the use of preventive measures between the groups. One-third of the experimental group claimed to have paid more attention to protection due to the information given in the leaflet. Conclusions: There is generally a lack of knowledge on leishmaniasis with a great feeling of need for more and detailed information. Correct and complete information on leishmaniasis should be included in the health advice for travelers to endemic areas. [source] A Partially Observed Model for Micromovement of Asset Prices with Bayes Estimation via FilteringMATHEMATICAL FINANCE, Issue 3 2003Yong Zeng A general micromovement model that describes transactional price behavior is proposed. The model ties the sample characteristics of micromovement and macromovement in a consistent manner. An important feature of the model is that it can be transformed to a filtering problem with counting process observations. Consequently, the complete information of price and trading time is captured and then utilized in Bayes estimation via filtering for the parameters. The filtering equations are derived. A theorem on the convergence of conditional expectation of the model is proved. A consistent recursive algorithm is constructed via the Markov chain approximation method to compute the approximate posterior and then the Bayes estimates. A simplified model and its recursive algorithm are presented in detail. Simulations show that the computed Bayes estimates converge to their true values. The algorithm is applied to one month of intraday transaction prices for Microsoft and the Bayes estimates are obtained. [source] GROWTH AND MEASUREMENT UNCERTAINTY IN AN UNREGULATED FISHERYNATURAL RESOURCE MODELING, Issue 3 2009ANNE B. JOHANNESEN Abstract Complete information is usually assumed in harvesting models of marine and terrestrial resources. In reality, however, complete information never exists. Fish and wildlife populations often fluctuate unpredictably in numbers, and measurement problems are frequent. In this paper, we analyze a time-discrete fishery model that distinguishes between uncertain natural growth and measurement error and in which exploitation takes place in an unregulated manner. Depending on the parameterization of the model and at which point of time uncertainty is resolved, it is shown that expected harvest under ecological uncertainty may be below or above that of the benchmark model with no uncertainty. On the other hand, when stock measurement is uncertain, expected harvest never exceeds the benchmark level. We also demonstrate that the harvesting profit, or rent, under uncertainty may be above that of the benchmark situation of complete information. In other words, less information may be beneficial for the fishermen. [source] Psychometric performance and clinical meaningfulness of the Patient Assessment of Constipation , Quality of Life questionnaire in prucalopride (RESOLOR®) trials for chronic constipationNEUROGASTROENTEROLOGY & MOTILITY, Issue 2 2010D. Dubois Abstract Background, The Patient Assessment of Constipation,Quality of Life (PAC-QOL) is a self-reported questionnaire measuring health-related quality of life (HRQL) of constipated patients and was used as secondary endpoint in three identical double-blind, randomized, placebo-controlled Phase III clinical trials. These 12-week trials in subjects with severe chronic constipation evaluated the effects of prucalopride, a selective 5-HT4 agonist given orally once daily. Methods, To consolidate the main treatment effect results observed in the prucalopride trial populations, analyses were undertaken on the pooled data of the three trials to confirm the psychometric properties of the PAC-QOL and to provide guidance for the interpretation of the clinical significance of its scores. Key Results, The evaluation of the psychometric properties confirmed the PAC-QOL reliability, validity and responsiveness to measure the impact of chronic constipation symptoms on HRQL in the prucalopride trials. The 1-point improvement in PAC-QOL scores used as target response level for the main treatment effect analyses was validated as a relevant definition of response for treatment group comparisons. Cumulative distribution curves, drawn for each treatment group to provide more complete information on treatment effects than single minimal important difference point estimates, demonstrated consistent superior effects of prucalopride over placebo on all PAC-QOL scores. Conclusions & Inferences, The PAC-QOL questionnaire is a useful measurement tool to assess, from a patient perspective, the potential therapeutic value of chronic constipation treatments in clinical trials and, by directly reflecting the patient's own perspective on constipation and its treatment, eventually also for informing daily medical practice. [source] Computation and presentation of graphs displaying closure hierarchies of Jordan and Kronecker structuresNUMERICAL LINEAR ALGEBRA WITH APPLICATIONS, Issue 6-7 2001Erik Elmroth Abstract StratiGraph, a Java-based tool for computation and presentation of closure hierarchies of Jordan and Kronecker structures is presented. The tool is based on recent theoretical results on stratifications of orbits and bundles of matrices and matrix pencils. A stratification reveals the complete hierarchy of nearby structures, information critical for explaining the qualitative behaviour of linear systems under perturbations. StratiGraph facilitates the application of these theories and visualizes the resulting hierarchy as a graph. Nodes in the graph represent orbits or bundles of matrices or matrix pencils. Edges represent covering relations in the closure hierarchy. Given a Jordan or Kronecker structure, a user can obtain the complete information of nearby structures simply by mouse clicks on nodes of interest. This contribution gives an overview of the StratiGraph tool, presents its main functionalities and other features, and illustrates its use by sample applications. Copyright © 2001 John Wiley & Sons, Ltd. [source] IMPERFECT INFORMATION AND DIFFERENCES IN HOME OWNERSHIP INVESTMENTPACIFIC ECONOMIC REVIEW, Issue 4 2004Keiko Nosse Hirono We study the advantages accruing to buyers who have complete information and who can pay less than the equilibrium price if sellers undervalue their properties. The reduction in home ownership investment can increase consumption or investment in other assets. We develop an empirical model to capture the gain to such buyers. We estimate this to have been 12.6%,27.6% of the equilibrium price of houses at maximum in the Tokyo metropolitan area during the 1980s. [source] HRTEM, Raman and optical study of CdS1,xSex nanocrystals embedded in silicate glassPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 13 2004V. Bellani Abstract We studied CdS1,xSex nanocrystals embedded in a silicate glass by means of complementary techniques like high resolution transmission electron microscopy (HRTEM), micro-Raman spectroscopy and optical transmission and reflectivity. Transmission Electron Microscopy gives complete information on crystallization and size distribution of the nanocrystals wile Raman scattering is particularly useful in the determination of the composition of the nanocrystals for low-concentration or small-crystallite size composite. Having the size distribution and composition of the nanocrystals we have explained the transmission spectra of the studied samples. Optical transmission spectra evidence the quantization of the electronic states of the nanoparticles system with a size distribution described by a Gaussian function. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Latest news and product developmentsPRESCRIBER, Issue 12 2007Article first published online: 4 OCT 200 NAO: GPs still not prescribing efficiently The National Audit Office (NAO) says NHS funds are being wasted through inefficient GP prescribing and patients not taking their medicines. The NAO's long-awaited report, Prescribing Costs in Primary Care (www.nao.org.uk), found large variations between PCTs in generic prescribing of statins, ACE inhibitors and angiotensin-II antagonists, and protonpump inhibitors; PCTs were also paying widely differing prices for these products. There was a five-fold variation in prescribing volume for clopidogrel between PCTs. These four drugs accounted for only 19 per cent of total spending but, if all practices matched the performance of the best 25 per cent, the NHS would save £200 million annually. PCTs should do more to rationalise prescribing and support their GPs, the NAO concludes. The NAO says that the cost of medicines dispensed for but not taken by patients lies somewhere in the range £100-£800 million annually. Strategies to reduce waste include public awareness campaigns and restricting supplies to four weeks (or two weeks for new medicines). Rosiglitazone may increase CV death risk A meta-analysis of 42 clinical trials has suggested that rosiglitazone is associated with increased risks of myocardial infarction (MI) and cardiovascular death (N Engl J Med 2007; published online 21 May: doi 10.1056/ NEJMoa072761). Like the COX-2 inhibitors, rosiglitazone was licensed without determining its possible effects on long-term cardiovascular outcomes, and interpretation of the latest findings is complicated by the multiple comparisons involved. For risk of MI, there was no significant difference between rosiglitazone and placebo (though this was of borderline statistical signifi-cance , p=0.07), metformin, sulphonylureas or insulin. Rosiglitazone was associated with a statistically significant 43 per cent increased risk compared with all comparators combined but the absolute increase in risk was very small (0.02 per cent). The trends were similar for risk of cardiovascular death, though rosiglitazone was associated with a 64 per cent increased risk compared with all comparators combined that was of borderline statistical significance (p=0.06). The authors acknowledge that their analysis pooled short-term studies that excluded patients at risk of heart disease and was not designed to determine cardiovascular outcomes, and they had no access to patientlevel data; as a result, there is uncertainty about their findings. Nevertheless, they say there is now an urgent need to clarify the risk associated with rosiglitazone. GlaxoSmithKline has rebutted the findings, stating that the cardiovascular risk profile of rosiglitazone is comparable with that of other oral antidiabetic drugs. The MHRA says warnings in the current SPCs for Avandia and Avandamet already reflect most of the data in the latest US review. The possible effects of rosiglitazone on cardiovascular events is currently being evaluated in the Rosiglitazone Evaluated for Cardiac Outcomes and Regulation of glycaemia in Diabetes (RECORD) study. Good management tool The Department of Health has published a disease management tool to enable PCTs to model local interventions that could reduce emergency admissions. The web-based ,voluntary good practice tool' will demonstrate how interventions in primary care and social care settings can improve the management of long-term conditions including cardiovascular disease, asthma and COPD, and dementia and depression. Counterfeit medicines The MHRA has issued an unprecedented three alerts about fake medicines in the legitimate supply chain, recalling all affected lot numbers. Three batches of Zyprexa 10mg tablets (olanzapine) were withdrawn after a company printing labels became suspicious and alerted Eli Lilly. Two of the batches, which contained 60 per cent of the stated active ingredient, had reached patients but no adverse events were reported. Two lots of parallel-imported Plavix 75mg tablets (clopidogrel) have been withdrawn after counterfeit packs were identified. The lots were in French original packaging but will have been overlabelled for the UK market. The counterfeits were mixed with genuine packs from Sanofi-Aventis. Fake Casodex 50mg tablets (bicalutamide) have been identified in a parallel import from France. The Royal Pharmaceutical Society reports that the fake contains 75 per cent of the stated dose of bicalutamide. Alcohol-free mometasone Schering-plough has introduced an alcohol-free formulation of mometasone furoate nasal spray (Nasonex) for hay fever. The company says that an alcohol vehicle causes nasal irritation and leaves an unpleasant aftertaste, adding that over 40 per cent of patients cite this as the main reason for stopping treatment, and over 50 per cent state a preference for an alcohol-free product. Aid to improve statin adherence Adherence to statin therapy can be improved if patients use a decision aid when they are offered treatment,US investigators say (Arch Intern Med 2007;167:1076-82). The decision aid estimated the individual's 10-year cardiovascular risk and the risk reduction from treatment, and summarised the disadvantages of statins.Patients with diabetes who used the aid knew more about their risk and were less indecisive about treatment than those who did not. The odds of having missed a dose over three months were three times higher for patients who had not used the aid. Online tool calculates switch savings A new online tool can help GPs estimate the savings achievable from switching patients to cheaper medicines. The Switch Saving Calculator, developed by the Prescribing Analysis & Support Team at the NHS Regional Drug and Therapeutics Centre in Newcastle, calculates potential savings based on past, current or projected use of the target drug. It can be applied to individual prescribers or scaled up to practice, commissioning group, PCT, health authority or even national level. Separate calculators are available for primary and secondary care. The current version calculates potential savings by switching from atorvastatin to simvastatin. The Newcastle team says other drugs will be added and they will update prices regularly. The calculator is at www.nyrdtc.nhs.uk:80/Services/presc_supp/ switch_saving_calculator/switch_saving_calculator.html. No improvement in drug information for patients leaving hospital The information given to patients discharged from hospital is not improving, according to the Healthcare Commission's annual patient survey (www.healthcare commission.org.uk). The 2006 survey found that the commonest reason patients were kept waiting for at least four hours to leave hospital was the delay in providing discharge medicines. Provision of written information increased from 62 per cent of patients in 2005 to 65 per cent in 2006. However, only 76 per cent said they had been told about their medicines in a way they could ,completely' understand (79 per cent in 2002). The proportion of patients reporting complete information about sideeffects also fell (from 40 per cent in 2005 to 37 per cent). Aspirin in preeclampsia A new meta-analysis has found that primary prevention with low-dose aspirin modestly but consistently reduces the risk of preeclampsia (Lancet 2007; published online 18 May). The study of 31 trials involving 32 217 women at low to moderate risk found that antiplatelet agents (mostly aspirin) reduced the risk of pre-eclampsia and preterm birth by 10 per cent without an increased risk of bleeding. The benefit was similar across subgroups. There were also nonsignificant reductions in the risk of small for age, stillborn and death before discharge. New from NICE NICE approves varenicline for NHS NICE has endorsed the use of varenicline (Champix) as an aid to smoking cessation within the NHS for England and Wales; it has already been approved for use in Scotland by the Scottish Medicines Consortium. Varenicline is a partial agonist at the ,4,2 nicotinic receptor. It alleviates craving and withdrawal symptoms, and reduces the rewarding and reinforcing effects of smoking. The commonest adverse effect is mild to moderate nausea, which improves with time.1 Varenicline is licensed for smoking cessation in adults; NICE says it should be offered as an option for smokers who say they want to quit as part of a programme of behavioural support. However, treatment should not be withheld if counselling and support are not available. NICE was critical of manufacturer Pfizer's economic arguments in favour of varenicline, which inappropriately included US data, assumed a single quit attempt and may have overestimated its efficacy. It nonetheless concluded that varenicline is more effective than nicotine replacement therapy (NRT) or bupropion (Zyban) in achieving continuous abstinence. NICE estimated that, compared with NRT, the odds of abstinence at one year with varenicline were 54 per cent greater. A Cochrane review1 concluded that abstinence was 66 per cent more likely with varenicline than with bupropion, and three times more likely than with placebo. There was also a benefit from offering smokers a wider choice of treatments. A 12-week course of varenicline costs £163.80; it is also licensed for an additional 12-week course and dose tapering may be considered for those at high risk of relapse. The final appraisal determination does not state which is the treatment of first choice for smoking cessation. NICE is currently preparing guidance on smoking cessation in pri-mary care, pharmacies and workplaces. Copyright © 2007 Wiley Interface Ltd [source] Sourcing Through Auctions and AuditsPRODUCTION AND OPERATIONS MANAGEMENT, Issue 2 2008Ying-Ju Chen Buyers often find that obtaining complete information about suppliers is costly. In such scenarios, there is a trade-off between the costs of obtaining information and the benefits that accrue to the owners of such information. There are also various ways in which the missing information can be obtained or inferred. In this paper, we compare the efficiency of obtaining information via the classical mechanism design approach, which relies on the information available before the contracts are designed, with that of an "audit-based" approach, which relies on the information obtained after the fact. In our model, a single buyer (the Stackelberg leader) wishes to procure a package of products or services from various competing suppliers that possess private cost information. We allow for arbitrary cost and revenue functions and can incorporate multiple cost and revenue drivers. We show how the buyer can optimize her profit and at the same time coordinate the channel by using a contract scheme involving auctions, audits, and profit sharing. We also examine the behavior of this mechanism when the supplier can exert effort to reduce cost but the cost of effort cannot be verified. We propose several mechanisms for different precontract informational scenarios and compare their performance. [source] Scaling turbulent atmospheric stratification.THE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 631 2008III: Space, time stratification of passive scalars from lidar data Abstract In this third and final part of the series, we concentrate on the temporal behaviour of atmospheric passive scalars. We first recall that,although the full (x, y, z, t) turbulent processes respect an anisotropic scale invariance,that due to advection,the generator will generally not be a diagonal matrix. This implies that the scaling of (1-D) temporal series will generally involve three exponents in real space: 1/3, 1/2, 3/5, for spectra ,, = 5/3, 2, 11/5, with the first and last corresponding to domination by advection (horizontal and vertical respectively), and the second to pure temporal development (no advection). We survey the literature and find that almost all the empirical ,, values are indeed in the range 5/3 to 2. We then use meteorological analyses to argue that, although pure temporal development is unlikely to be dominant for time-scales less than the eddy turnover time of the largest structures (about 2 weeks), an intermittent vertical velocity could quite easily explain the occasionally observed ,, , 2 spectra. We then use state-of-the-art vertically pointing lidar data of backscatter ratios from both aerosols and cirrus clouds yielding several (z, t) vertical space,time cross-sections with resolution of 3.75 m in the vertical, 0.5,30 s in time and spanning 3,4 orders of magnitude in temporal scale. We first test the predictions of the anisotropic, multifractal extension of the Corrsin-Obukhov law in the vertical and in time, separately finding that the cirrus and aerosol backscatters both followed the theoretical (anisotropic) scalings accurately; three of the six cases show dominance by the horizontal wind, the others by the vertical wind. In order to test the theory in arbitrary directions in this (z, t) space, and in order to get more complete information about the underlying physical scale, we develop and apply a new Anisotropic Scaling Analysis Technique (ASAT) which is based on a nonlinear space,time coordinate transformation. This transforms the original differential scaling into standard self-similar scaling; there remains only a ,trivial' anisotropy. This method is used in real space on 2-D structure functions. It is applied to both the new (z, t) data as well as the (x, z) data discussed in part II. Using ASAT, we verify the theory to within about 10% over more than three orders of magnitude of space,time scales in arbitrary directions in (x, z) and (z, t) spaces. By considering the high- (and low-) order structure functions, we verify the theory for both weak and strong structures; as predicted, their average anisotropies are apparently the same. Putting together the results for (x, z) and (z, t), and assuming that there is no overall stratification in the horizontal (x, y) plane, we find that the overall (x, y, z, t) space is found to have an effective ,elliptical dimension' characterizing the overall space,time stratification equal to Deff, st = 3.21 ± 0.05. Copyright © 2008 Royal Meteorological Society [source] Impact and Quantification of the Sources of Error in DNA Pooling DesignsANNALS OF HUMAN GENETICS, Issue 1 2009A. Jawaid Summary The analysis of genome wide variation offers the possibility of unravelling the genes involved in the pathogenesis of disease. Genome wide association studies are also particularly useful for identifying and validating targets for therapeutic intervention as well as for detecting markers for drug efficacy and side effects. The cost of such large-scale genetic association studies may be reduced substantially by the analysis of pooled DNA from multiple individuals. However, experimental errors inherent in pooling studies lead to a potential increase in the false positive rate and a loss in power compared to individual genotyping. Here we quantify various sources of experimental error using empirical data from typical pooling experiments and corresponding individual genotyping counts using two statistical methods. We provide analytical formulas for calculating these different errors in the absence of complete information, such as replicate pool formation, and for adjusting for the errors in the statistical analysis. We demonstrate that DNA pooling has the potential of estimating allele frequencies accurately, and adjusting the pooled allele frequency estimates for differential allelic amplification considerably improves accuracy. Estimates of the components of error show that differential allelic amplification is the most important contributor to the error variance in absolute allele frequency estimation, followed by allele frequency measurement and pool formation errors. Our results emphasise the importance of minimising experimental errors and obtaining correct error estimates in genetic association studies. 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