Common Baseline Research Articles

Using anchor text for homepage and topic distillation search tasks

Past work suggests that anchor text is a good source of evidence that can be used to improve web searching. Two approaches for making use of this evidence include fusing search results from an anchor text representation and the original text representation based on a document's relevance score or rank position, and combining term frequency from both representations during the retrieval process. Although these approaches have each been tested and compared against baselines, different evaluations have used different baselines; no consistent work enables rigorous cross-comparison between these methods. The purpose of this work is threefold. First, we survey existing fusion methods of using anchor text in search. Second, we compare these methods with common testbeds and web search tasks, with the aim of identifying the most effective fusion method. Third, we try to correlate search performance with the characteristics of a test collection. Our experimental results show that the best performing method in each category can significantly improve search results over a common baseline. However, there is no single technique that consistently outperforms competing approaches across different collections and search tasks.

CFD Analysis of Wind Loads on Permeable Low-Rise Structures

Current screen enclosure building codes are based on the experimental wind tunnel studies and, to a smaller extent, full scale open terrain studies conducted at Virginia Tech and Clemson University. There are still widespread wind damages to pool and patio enclosures during wind storms. Experimental studies based on simulation comparison of wind load on a low-rise structure in general, continue to show large discrepancies based on NIST data. Accounting for the many parameters which are essential to achieve an accurate simulation through experimentation is daunting. Reynolds number, spectrum density, large and small turbulent scales, viscous shear layer, and flow intermittency are a few of those parameters. Numerical simulation (CFD) provides an attractive parametric study and offers a richer, higher resolution data output. In this work, flow around a screen enclosure embedded within the atmospheric boundary layer is investigated numerically. The flow is governed by Navier-Stokes equations with a momentum sink that follows Darcy equations and incorporating the eddy viscosity k-ε turbulent closure model. The pressure drop that is computed provides the basis of evaluating wind load on the screen structure. The evaluated load is compared to the Florida Building Code ASCE7 provision and is used to conduct structural analysis on common baseline enclosures to assess their reliability. The structure is analyzed using Bernoulli-Euler beam elements having cross sections according to the code and subjected to forces and moments with 6 (3displacements and 3 rotational) degrees of freedom.

The International Community-Acquired Pneumonia (CAP) Collaboration Cohort (ICCC) study: rationale, design and description of study cohorts and patients

ObjectiveTo improve the understanding of the determinants of prognosis and accurate risk stratification in community-acquired pneumonia (CAP).DesignMulticentre collaboration of prospective cohorts.Setting6 cohorts from the USA, Canada, Hong Kong and Spain.ParticipantsFrom...

The Incidence of Bcr-Abl Mutations and Their Impact on Clinical Outcome in Newly Diagnosed Chronic Phase Chronic Myeloid Leukemia Patients Treated with Bosutinib Versus Imatinib in the BELA Trial

Abstract 2769In the phase 3 BELA study, bosutinib was associated with superior rates of major molecular response (MMR) at 12 months, faster times to MMR and complete cytogenetic response (CCyR), fewer on-treatment events of transformation to accelerated/blast phase CML, and fewer overall deaths on study when compared with imatinib; each agent was associated with an acceptable but distinct safety profile. However, clinical resistance to TKIs commonly results from development of Bcr-Abl mutations. Therefore, we investigated the incidence of Bcr-Abl mutations and their impact on clinical outcome in the BELA trial.Newly diagnosed patients (pts) with CP CML were randomized to bosutinib 500 mg/day (n = 250) or imatinib 400 mg/day (n = 252). Direct sequencing of Bcr-Abl kinase domain (10%-20% sensitivity) in a central laboratory was employed at baseline (bosutinib, n = 237; imatinib, n = 241) as well as at treatment discontinuation (bosutinib, n = 62; imatinib, n = 49).The median age was 48 years (range, 19–91 years) in the bosutinib arm and 47 years (range, 18–89 years) in the imatinib arm. Based on a minimum of 18 months from the last pt randomized, median treatment duration was 22.0 months for both treatment arms; 33% (n = 81) of pts in the bosutinib arm and 26% (n = 66) of pts in the imatinib arm have discontinued treatment. The primary reason for discontinuation of bosutinib was treatment-related toxicity (22% vs 6% with imatinib), while the primary reason for discontinuation of imatinib was disease progression (13% vs 4% with bosutinib); all other reasons for discontinuation were reported for ≤3% of pts in either arm.At baseline, already present Bcr-Abl polymorphisms were equally distributed among the 2 arms (bosutinib, n = 24; imatinib, n = 17). The most common baseline polymorphisms were E499E (bosutinib, n = 18; imatinib, n = 10), 499E/E or 499E/E variant (bosutinib, n = 3; imatinib, n = 1), and T83T (bosutinib, n = 0; imatinib, n = 4); additional polymorphisms detected in at least one of the treatment arms included E197K, K247R, T240T, and Y320C.As of the database snapshot, 81 pts had discontinued treatment in the BOS arm compared with 66 pts in the IM arm, of which 62 (77%) pts in the BOS arm and 49 (74%) pts in the IM arm had a sample collected at treatment discontinuation. Of these, 37/62 (60%) pts in the BOS arm did not have a detectable mutation and 28/49 (57%) pts in the IM arm did not have a detectable mutation.Four (6%) pts had a detectable mutation in the BOS arm (T315I [n = 2], E255K, and V299L [n = 1 each]) compared with 10 (21%) pts in the IM arm (G250E [n = 2], M244V [n = 2], Q252H, Y253H, E255K, M244V/M351T, D276G/H396R, and D276G/T277A/T315I [n = 1 each]) at the time of treatment discontinuation. In the BOS arm, 1 pt with the V299L mutation achieved CCyR (time to CCyR of 254 days). In the IM arm, 1 pt with the G250E mutation achieved both CCyR and MMR (time to response of 252 days for both) and 2 pts with the M244V and D276G/T277A/T315I mutations achieved CCyR (times to CCyR of 254 and 340 days, respectively). Treatment failure was experienced by 2/4 pts in the BOS arm with a mutation (E255K and T315I) compared with 7/10 pts in the IM arm (M244V [n = 2], G250E, Q252H, Y253H, M244V/M351T, and D276G/H396R). An on-treatment event of transformation to accelerated/blast phase CML was experienced by 2/4 pts in the BOS arm (E255K and T315I) versus 5/10 pts in the IM arm (G250E, Q252H, Y253H, M244V/M351T, and D276G/H396R). Among pts with a new mutation detected at treatment completion, 2 deaths were reported in each treatment arm; all 4 deaths occurred after discontinuation of study treatment.In conclusion, baseline and emergent Bcr-Abl kinase domain mutations were detected in both treatment arms, with polymorphisms at the E499 position the most common. In this analysis, imatinib was associated with a higher rate of progressive disease compared with bosutinib among pts with new mutations at treatment discontinuation; a similar trend has been observed in the overall study population. Additional follow-up will allow for more complete mutational analysis. Disclosures:Kim:Pfizer Inc: Consultancy, Research Funding; BMS: Consultancy, Honoraria, Research Funding, Speakers Bureau; Novartis: Consultancy, Honoraria, Research Funding, Speakers Bureau; Ariad: Research Funding. Cortes:Pfizer Inc: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Novartis: Consultancy, Research Funding. Wong:Pfizer Inc: Research Funding; Novartis: Honoraria, Research Funding, Speakers Bureau; GSK: Research Funding; Bayer: Honoraria, Research Funding; Sanofi: Research Funding; Biogen Idec: Honoraria, Research Funding; Roche: Research Funding; Leo Pharma: Honoraria. Duvillie:Pfizer Inc: Employment. Powell:Pfizer Inc: Employment, Equity Ownership. Countouriotis:Pfizer Inc: Employment. Brümmendorf:Pfizer Inc: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Patents & Royalties, Research Funding; BMS: Consultancy, Honoraria.

Marginal hazard regression for correlated failure time data with auxiliary covariates

In many biomedical studies, it is common that due to budget constraints, the primary covariate is only collected in a randomly selected subset from the full study cohort. Often, there is an inexpensive auxiliary covariate for the primary exposure variable that is readily available for all the cohort subjects. Valid statistical methods that make use of the auxiliary information to improve study efficiency need to be developed. To this end, we develop an estimated partial likelihood approach for correlated failure time data with auxiliary information. We assume a marginal hazard model with common baseline hazard function. The asymptotic properties for the proposed estimators are developed. The proof of the asymptotic results for the proposed estimators is nontrivial since the moments used in estimating equation are not martingale-based and the classical martingale theory is not sufficient. Instead, our proofs rely on modern empirical process theory. The proposed estimator is evaluated through simulation studies and is shown to have increased efficiency compared to existing methods. The proposed method is illustrated with a data set from the Framingham study.

Estimated Generalized Estimating Equation for Correlated Failure Time Data with Auxiliary Covariates

In this article, we study a marginal hazard model with common baseline hazard for correlated failure time data. We assume that the true covariate is measured precisely in a subset of the whole study cohort, whereas an auxiliary information for the true covariate is available for the whole cohort. We first estimate the relative risk function empirically. Then we obtain the estimator for the regression parameter by replacing the relative risk function with its estimator in a generalized estimating equation (GEE) proposed by Cai (1992). A key feature of this method is that it is nonparametric with respect to the association between the missing covariate and the observed auxiliary covariate. The proposed estimator is shown to be consistent and asymptotically normal. Furthermore, we present a corrected Breslow-type estimator for the cumulative hazard function. Simulation studies are conducted to evaluate the proposed method.

Conclusion: From Rule of Law Promotion to Rule of Law Dynamics

In The Dynamics of Rule of Law in an Era of International and Transnational Governance (forthcoming Cambridge University Press, 2012), we presented a new analytical framework for understanding developments in the rule of law field, describing and assessing the interrelated processes of rule of law promotion, diffusion and conversion. In this concluding chapter, we address the following issues, taking up in turn rule of law promotion, diffusion and conversion, and summarizing for each the main developments, their causes, and key issues for further research. Have the major actors in the rule of law field, including the “great powers” and international organisations, altered their strategies, programs and practices to reflect the shift to new levels and new forms of governance? Do rule of standards apply to new international and transnational forms of regulation? Should they be modified to fit the different context? Can the interactions between national and international levels be structured so that they do not become a new source of rule of law violation? Does international law provide a clear and acceptable set of standards that can form a common baseline for rule of law promotion both in states and for new forms of governance? And how does rule of law promotion, whether or not based on standards of international law, cope with the wide variety of forms of resistance from the targets of rule of law promotion?

A standardized protocol to reduce cerebrospinal fluid shunt infection: The Hydrocephalus Clinical Research Network Quality Improvement Initiative

Quality improvement techniques are being implemented in many areas of medicine. In an effort to reduce the ventriculoperitoneal shunt infection rate, a standardized protocol was developed and implemented at 4 centers of the Hydrocephalus Clinical Research Network (HCRN). The protocol was developed sequentially by HCRN members using the current literature and prior institutional experience until consensus was obtained. The protocol was prospectively applied at each HCRN center to all children undergoing a shunt insertion or revision procedure. Infections were defined on the basis of CSF, wound, or pseudocyst cultures; wound breakdown; abdominal pseudocyst; or positive blood cultures in the presence of a ventriculoatrial shunt. Procedures and infections were measured before and after protocol implementation. Twenty-one surgeons at 4 centers performed 1571 procedures between June 1, 2007, and February 28, 2009. The minimum follow-up was 6 months. The Network infection rate decreased from 8.8% prior to the protocol to 5.7% while using the protocol (p = 0.0028, absolute risk reduction 3.15%, relative risk reduction 36%). Three of 4 centers lowered their infection rate. Shunt surgery after external ventricular drainage (with or without prior infection) had the highest infection rate. Overall protocol compliance was 74.5% and improved over the course of the observation period. Based on logistic regression analysis, the use of BioGlide catheters (odds ratio [OR] 1.91, 95% CI 1.19-3.05; p = 0.007) and the use of antiseptic cream by any members of the surgical team (instead of a formal surgical scrub by all members of the surgical team; OR 4.53, 95% CI 1.43-14.41; p = 0.01) were associated with an increased risk of infection. The standardized protocol for shunt surgery significantly reduced shunt infection across the HCRN. Overall protocol compliance was good. The protocol has established a common baseline within the Network, which will facilitate assessment of new treatments. Identification of factors associated with infection will allow further protocol refinement in the future.

Cloud computing services: taxonomy and comparison

Cloud computing is a highly discussed topic in the technical and economic world, and many of the big players of the software industry have entered the development of cloud services. Several companies what to explore the possibilities and benefits of incorporating such cloud computing services in their business, as well as the possibilities to offer own cloud services. However, with the amount of cloud computing services increasing quickly, the need for a taxonomy framework rises. This paper examines the available cloud computing services and identifies and explains their main characteristics. Next, this paper organizes these characteristics and proposes a tree-structured taxonomy. This taxonomy allows quick classifications of the different cloud computing services and makes it easier to compare them. Based on existing taxonomies, this taxonomy provides more detailed characteristics and hierarchies. Additionally, the taxonomy offers a common terminology and baseline information for easy communication. Finally, the taxonomy is explained and verified using existing cloud services as examples.

Establishing length-at-age references in the red mullet, Mullus barbatus L. 1758 (Pisces, Mullidae), a case study for growth assessments in the Mediterranean Geographical Sub-Areas (GSA)

Length at age data are a fundamental tool for the assessment of exploited fish populations, their use requiring the identification of the ‘unit stock’. At the present, however, the spatial reference for stock assessment in the Mediterranean Sea is based on a grid of 30 arbitrary Geographical Sub Areas (GSA). Since older data rarely respect the GSA borders, the authors propose to reconstruct the historical data within a common frame and to assess a single reference length at age, together with the corresponding von Bertalanffy growth parameters, to be used as a broad benchmark for analyses inter and intra GSAs. This approach was tested using, as a case study, the red mullet (Mullus barbatus L. 1758), one of the most investigated fish of the whole Mediterranean basin. Published and grey literature was browsed, to get direct and/or indirect length at age estimations. To establish a common baseline and maximize the use of partial information, a vBGF (L∞, total length in mm, and Ky-1) was fitted to length at age data whenever possible. 56 Mediterranean sets were utilized; an overall reference growth line was estimated by sex, discussing its adequacy to the life traits of the species.

Clustering With Multi-Layer Graphs: A Spectral Perspective

Observational data usually comes with a multimodal nature, which means that it can be naturally represented by a multi-layer graph whose layers share the same set of vertices (objects) with different edges (pairwise relationships). In this paper, we address the problem of combining different layers of the multi-layer graph for an improved clustering of the vertices compared to using layers independently. We propose two novel methods, which are based on a joint matrix factorization and a graph regularization framework respectively, to efficiently combine the spectrum of the multiple graph layers, namely the eigenvectors of the graph Laplacian matrices. In each case, the resulting combination, which we call a “joint spectrum” of multiple layers, is used for clustering the vertices. We evaluate our approaches by experiments with several real world social network datasets. Results demonstrate the superior or competitive performance of the proposed methods compared to state-of-the-art techniques and common baseline methods, such as co-regularization and summation of information from individual graphs.

P2.20 Importance of baseline in event-related desynchronization during imaging observation

Introduction: To design a neurofeedback system (NF system) for clinical purposes (e.g. stroke rehabilitation) using imaging-observation of motor movements. Event-Related Desynchronization (ERD) of the mu rhythm (8-13 Hz) is vital to indicate the engagement between the patient’s brain and the NF system. One factor, which influences mu-ERD, is the mu-power during baseline conditions. A baseline movie is defined as a given visual input which can induce or maximize mu-power. Objective: To investigate the effects of various baseline movies on mu-ERD during imaging- observation. Methods: 10 healthy subjects performed the imaging-observation tasks while electroencephalograms (EEGs) were recorded using 60 channels. In each trial, 5 different baseline movies were shown: i) a bouncing ball (BL), ii) a slowly moving flower (FL), iii) a static right hand (SH), iv) two randomly moving balls (2B) and v) a black screen with white stripes (BW). A right hand grasping movie was shown after every baseline. C3 channel was selected for further statistical analysis due to its direct relation with imaging right hand grasping. ANOVA (α=0.05) was performed to test mu-power differences among baselines. Finally, the topographical mu-ERDs were plotted and visually inspected. Results: At the group level, ANOVA of baseline mu-powers revealed no common baseline movie which maximized mu-power. According to the ERD plots, there was no significant difference in the ERD between the five baseline movies. At the individual level, each subject showed relatively high mu-power only in some particular baselines. Thus, the ERD for each subject was dependent on the baseline used. Conclusion: Choice of baseline movie affects ERD during imaging-observation, with significant inter-individual differences.

Bioavailability of Vitamin D in Malnourished Adolescents with Anorexia Nervosa

Young women with anorexia nervosa (AN) have a normal vitamin D status. The bioavailability of vitamin D during malnutrition is unknown. The objective of the study was to examine the serum response to oral ergocalciferol in AN. This was a prospective cohort study, conducted in 2007-2009 at a tertiary care center. Twelve adolescents with AN (age 19.6 ± 2.0 yr, body mass index 16.5 ± 1.4 kg/m²) and 12 matched healthy controls (20.0 ± 2.4 yr, 22.7 ± 1.0 kg/m²) received one baseline 50,000 IU oral dose of ergocalciferol. Serum D₂, D₃, 25-hydroxyvitamin D, and 1,25-dihydroxyvitamin D, collected before ingestion, at 6 and 24 h and weekly for 4 wk, and body composition measures were measured. The AN group was severely malnourished (77.2 ± 6.3% median body weight), whereas the control group was normal weighted (106.2 ± 6.2%). From a common baseline D₂ (1.5 ± 1.6 nmol/liter, P =0.34) the groups diverged (time × group interaction P = 0.04), peaking at 70 ± 34 nmol/liter at 6 h in controls compared with 43 ± 28 nmol/liter in AN subjects (P = 0.008). The D₂ trajectories converged at 24 h (57 nmol/liter, P = 0.98) and returned to near baseline at 1 wk. Baseline D₃ was higher in AN subjects (12.1 ± 9.6 vs. 3.1 ± 2.3 nmol/liter, P < 0.001) and remained higher throughout. 25-Hydroxyvitamin D followed a common trajectory (time × group interaction P = 0.15), rising to 45 ± 10 nmol/liter at 24 h but returning to baseline by wk 3 (P = 0.36). Correlating vitamin D levels with fat measures (body mass index, body fat) produced similar findings. Despite severe malnutrition, young women with AN had a similar bioavailability of oral ergocalciferol as the healthy-weighted controls. Vitamin D dosing for patients suffering from malnutrition may not differ from that for normal-weighted adolescents.

Deconstructing the mechanisms of angle closure with anterior segment optical coherence tomography

To illustrate the common mechanisms of angle closure by observing the changes following a laser iridotomy and then cataract surgery with anterior segment optical coherence tomography. Retrospective interventional case series. Four patients with iridotrabecular contact. The anterior chamber was imaged in different lighting conditions prior to and following a laser iridotomy and then cataract surgery. The images were superimposed on each other, using the interscleral spur line as a common baseline. Qualitative and quantitative analysis of the changes of the iris and the drainage angle. Iridotrabecular contact was seen in dark conditions in all patients. Iridotrabecular contact related to pupil block was abolished after a laser iridotomy. Persistent iridotrabecular contact following a laser iridotomy, due to a lens-induced mechanism, was abolished after cataract surgery. Iridotrabecular contact that persisted after a laser iridotomy and cataract surgery was due to a 'pure' plateau iris syndrome or peripheral anterior synechiae. These treatments lowered the height of the iris plane in the region posterior to the trabecular meshwork. Following a laser iridotomy and cataract surgery, there is posterior movement of the iris plane away from the trabecular meshwork, but iridotrabecular contact can persist due to the ciliary processes or peripheral anterior synechiae. These changes show that the risk of iridotrabecular contact depends on the height of the iris plane relative to the trabecular meshwork and the degree of physiologic pupil dilation, and that angle closure can be a multi-mechanism disease rather than a pure one.

Natural history and physiological determinants of changes in glucose tolerance in a non-diabetic population: the RISC Study

The natural history and physiological determinants of glucose intolerance in subjects living in Europe have not been investigated. The aim of this study was to increase our understanding of this area. We analysed the data from a population-based cohort of 1,048 non-diabetic, normotensive men and women (aged 30-60 years) in whom insulin sensitivity was measured by the glucose clamp technique (M/I index; average glucose infusion rate/steady-state insulin concentration) and beta cell function was estimated by mathematical modelling of the oral glucose tolerance test at baseline and 3 years later. Seventy-seven per cent of the participants had normal glucose tolerance (NGT) and 5% were glucose intolerant both at baseline and follow up; glucose tolerance worsened in 13% (progressors) and improved in 6% (regressors). The metabolic phenotype of the latter three groups was similar (higher prevalence of familial diabetes, older age, higher waist-to-hip ratio, higher fasting and 2 h plasma glucose, higher fasting and 2 h plasma insulin, lower insulin sensitivity and reduced beta cell glucose sensitivity with increased absolute insulin secretion). Adjusting for these factors in a logistic model, progression was predicted by insulin resistance (bottom M/I quartile, OR 2.52 [95% CI 1.51-4.21]) and beta cell glucose insensitivity (bottom quartile, OR 2.39 [95% CI 1.6-3.93]) independently of waist-to-hip ratio (OR 1.44 [95% CI 1.13-1.84] for one SD). At follow up, insulin sensitivity and beta cell glucose sensitivity were unchanged in the stable NGT and stable non-NGT groups, worsened in progressors and improved in regressors. Glucose tolerance deteriorates over time in young, healthy Europids. Progressors, regressors and glucose-intolerant participants share a common baseline phenotype. Insulin sensitivity and beta cell glucose sensitivity predict and track changes in glucose tolerance independently of sex, age and obesity.

A retrospective study of patch tests in Chongqing, China from 2004 to 2009

There has been no previous report on allergens responsible for dermatitis in southwest China. To investigate the prevalence of contact allergy in southwest China, we retrospectively analysed the patch testing results in our department from 2004 to 2009. A total of 2758 patients were patch tested with the Chinese baseline series of contact allergens (Beijing Medical University), the most common baseline series used in China. The results from patch tests were collected, analysed, and compared with clinical findings. Of 2758 patients tested, 1826 (66.2%) were allergic to one or more common allergens. Five hundred (27.4%) patients had more than two contact allergies. One patient showed positive reactions to seven allergens. The most common allergens among the 1826 patients with positive reactions were nickel sulfate (39.5%), potassium dichromate (13.5%), thiomersal (11.6%), fragrance mix (6.9%), and rubber mix IV (5.8%). Nickel sensitivity was more common in female patients, and potassium dichromate sensitivity was more common in male patients (p < 0.001). Contact allergy in southwest China has particular characteristics, and these findings should be helpful in the development of strategies to reduce contact allergy in this geographical region.

An Analysis of the Lack of Donor Pancreas Utilization From Younger Adult Organ Donors

Donor pancreas utilization rates for whole organ transplant have remained low and have decreased over time. To identify the reasons for nonuse of pancreas from donors who meet common baseline acceptance criteria, we examined Organ Procurement and Transplantation Network data from 2005 to 2007 and identified a subgroup of 1763 "potential pancreas donors" defined by age (19-40 years), body mass index (<30 kg/m), successful liver donation, and negative viral serology testing, which were not used. We characterize this cohort of potential donors including reasons for refusal, factors that may contribute to pancreas acceptance and function, and potential explanations for the lack of growth in pancreas organ utilization.

Glossary of technical terms in cognitive neuroscience

10–20 system An internationally recognized system to determine the location of EEG electrodes on the scalp. Morphologically exactly defined marks are used and electrodes are placed in reference to them in 10 and 20% steps, respectively 3D-MPRAGE A data acquisition sequence that produces detailed, threedimensional high-resolution structural images of the brain AC-PC (anterior to posterior commissure) The anterior commissure (AC) and posterior commissure (PC) are two structures in the brain that are used to define the Talairach coordinate system of the human brain. The anterior commissure is defined as the origin with coordinates (0, 0, 0) Baseline condition Experimental condition designed to provide a baseline measure of brain activity. Since fMRI measures relative states of regional blood flow, such conditions are essential. Common baseline conditions include eyes closed, or fixation (looking at a central point or cross with eyes open) Block Group of experimental trials Block design An fMRI design in which trials of each experimental condition are presented in separate blocks. Different experimental conditions are measured in blocks of trials and the activation associated with these blocks is then analysed BOLD (blood oxygenation level dependency) Oxygenated and deoxygenated hemoglobin differ in the magnetic susceptibility and thus represent a natural contrast agent in fMRI. The ratio of oxygenated to deoxygenated hemoglobin changes R. H. Grabner (&) Institute for Behavioral Sciences, Swiss Federal Institute of Technology (ETH) Zurich, Universitatsstrasse 41, UNO C15, 8092 Zurich, Switzerland e-mail: grabner@ifv.gess.ethz.ch

Proportional Hazards Regression for the Analysis of Clustered Survival Data from Case-Cohort Studies

Case-cohort sampling is a commonly used and efficient method for studying large cohorts. Most existing methods of analysis for case-cohort data have concerned the analysis of univariate failure time data. However, clustered failure time data are commonly encountered in public health studies. For example, patients treated at the same center are unlikely to be independent. In this article, we consider methods based on estimating equations for case-cohort designs for clustered failure time data. We assume a marginal hazards model, with a common baseline hazard and common regression coefficient across clusters. The proposed estimators of the regression parameter and cumulative baseline hazard are shown to be consistent and asymptotically normal, and consistent estimators of the asymptotic covariance matrices are derived. The regression parameter estimator is easily computed using any standard Cox regression software that allows for offset terms. The proposed estimators are investigated in simulation studies, and demonstrated empirically to have increased efficiency relative to some existing methods. The proposed methods are applied to a study of mortality among Canadian dialysis patients.

Adaptive population management advance in its theory and practice

Adaptive management (AM) is a practical process. This special feature includes three articles that introduce practical topics, eradication of exotic species, population management of irrupting wildlife, and international fisheries management. These population managements share common ideas (Shea et al. 1998). In general, the economic value of total ecosystem service V(C, N) consists of yield of harvest Y(H), cost of harvesting effort C(E), and value of standing biomass S(N), or V = Y C ? S, where N, H, and E are the standing stock biomass, amount of harvest, and harvesting effort. The yield of harvest is positive in fisheries, and is zero or negative in exotic species and pest animals. In classical fisheries, the value from standing biomass S(N) is usually ignored and seeks to maximize Y(H) (Matsuda et al. 2008). In invasive alien species and pest animals, S(N) is negative. Because of a common mathematical scheme in management of fisheries, wildlife, and exotic species, there is a common property for the optimal solution. Constant escapement is optimal for management of fisheries, exotic species, and probably pest animals, shown by Kotani et al. (2010) in this issue. Population management procedures for fisheries, wildlife, and invasive species usually face conflict between stakeholders. We expect that the scheme of AM gives a common baseline in scientific knowledge and may help consensus building. In fisheries management of southern bluefin tuna (SBT) by Kurota et al. (2010) in this issue, a pre-agreed set of rules determines how the total allowable catch (TAC) will be adjusted as new monitoring data become available. Sophisticated statistical methods including the Bayesian idea is being developed in AM, which fits well to the adaptive learning process of AM. However, in the case of SBT, the management procedure was not implemented because, shortly after its adoption, it became evident that historical catches may have been substantially underreported. The AM takes a variety of uncertainties (measurement error, process uncertainty, and implementation error) into account. Despite this attribute, the AM does not work well if the data are substantially biased by underreporting. Building trust between stakeholders is a key factor of fisheries and wildlife management (Levin 1999). The feasibility of these management programs definitely depends on cost-effectiveness, described in Kotani et al. (2010) in this issue. They focused on density-dependent catchability, or the ratio of harvest divided by effort and biomass (H/E/N). In Japan, ecologists have some opportunities to give advice on the management of wildlife and exotic species by national or local government as members of scientific councils. They can also give advice on world heritage issues, nature restoration projects, and environmental impact assessments. However, these advisory committees rarely discuss cost and budget. Therefore, these management programs are often not cost-effective. In the early stage of eradication programs, the population density and catch per unit effort (CPUE, defined as H/E) often rapidly decrease with a high catchability. The proportional relationship between CPUE and the population density is often expected, and it makes the feasibility of eradication program too optimistic. However, it is usually an illusion (Sasaki and Matsuda 2010). Due to over-harvesting, the sika deer (Cervus nippon) was threatened in Japan from the end of the nineteenth century to the mid-twentieth century. Since the midH. Matsuda (&) Faculty of Environment and Information Sciences, Yokohama National University, Yokohama, Japan e-mail: matsuda@ynu.ac.jp