bluuebunny/crossref_metadata_2025_split huggingface dataset:
Flexible modeling of competing risks in survival analysis
Authors: Belot Aurélien , Abrahamowicz Michal , Remontet Laurent , Giorgi Roch 
Published: July 2010

AbstractPrognostic studies often involve modeling competing risks, where an individual can experience only one of alternative events, and the goal is to estimate hazard functions and covariate effects associated with each event type. Lunn and McNeil proposed data manipulation that permits extending the Cox's proportional hazards model to estimate covariate effects on the hazard of each competing events. However, the hazard functions for competing events are assumed to remain proportional over the entire follow‐up period, implying the same shape of all event‐specific hazards, and covariate effects are restricted to also remain constant over time, even if such assumptions are often questionable. To avoid such limitations, we propose a flexible model to (i) obtain distinct estimates of the baseline hazard functions for each event type, and (ii) allow estimating time‐dependent covariate effects in a parsimonious model. Our flexible competing risks regression model uses smooth cubic regression splines to model the time‐dependent changes in (i) the ratio of event‐specific baseline hazards, and (ii) the covariate effects. In simulations, we evaluate the performance of the proposed estimators and likelihood ratio tests, under different assumptions. We apply the proposed flexible model in a prognostic study of colorectal cancer mortality, with two competing events: ‘death from colorectal cancer’ and ‘death from other causes’. Copyright © 2010 John Wiley & Sons, Ltd.
Joint modeling of missing data due to non‐participation and death in longitudinal aging studies
Authors: Rajan Kumar B. , Leurgans Sue E. 
Published: July 2010

AbstractSpecific age‐related hypotheses are tested in population‐based longitudinal studies. At specific time intervals, both the outcomes of interest and the time‐varying covariates are measured. When participants are approached for follow‐up, some participants do not provide data. Investigations may show that many have died before the time of follow‐up whereas others refused to participate. Some of these non‐participants do not provide data at later follow‐ups. Few statistical methods for missing data distinguish between ‘non‐participation’ and ‘death’ among study participants. The augmented inverse probability‐weighted estimators are most commonly used in marginal structure models when data are missing at random. Treating non‐participation and death as the same, however, may lead to biased estimates and invalid inferences. To overcome this limitation, a multiple inverse probability‐weighted approach is presented to account for two types of missing data, non‐participation and death, when using a marginal mean model. Under certain conditions, the multiple weighted estimators are consistent and asymptotically normal. Simulation studies will be used to study the finite sample efficiency of the multiple weighted estimators. The proposed method will be applied to study the risk factors associated with the cognitive decline among the aging adults, using data from the Chicago Health and Aging Project (CHAP). Copyright © 2010 John Wiley & Sons, Ltd.
How best to measure the levator hiatus: evidence for the non‐Euclidean nature of the ‘plane of minimal dimensions’
Authors: Kruger J. A. , Heap S. W. , Murphy B. A. , Dietz H. P. 
Published: July 2010

AbstractObjectiveTo clarify whether the ‘plane of minimal dimensions’ of the levator hiatus on three‐dimensional (3D) ultrasound accurately represents the minimal anatomical transverse hiatal dimension during a Valsalva maneuver.MethodsIn this retrospective study of 3D transperineal ultrasound and magnetic resonance (MR) imaging, datasets from 19 female participants were used to measure the transverse diameter of the levator hiatus using the plane of minimal dimensions on maximum Valsalva maneuver. The term ‘apparent minimal transverse diameter’ (aMTD) was used to define the transverse diameter measured using axial ultrasound and comparable axial or coronal MR images. Coronal MR images, using the plane of the vagina as a reference, were also obtained on maximum Valsalva. The transverse diameter measured between the caudal margin of the pubococcygeus/puborectalis on the MR coronal image is denoted by the term ‘true minimal transverse diameter’ (tMTD). Statistical comparisons between the aMTD and tMTD were made using Student's t‐test.ResultsNo significant difference was demonstrated between the aMTD as measured by ultrasonography and MRI. However, there were significant differences found between the aMTD measured by both ultrasound and MRI and the tMTD measured on coronal MR images (both P < 0.01), with mean ( ± SD) values of 4.36 ± 0.85, 4.13 ± 1.09 and 3.23 ± 0.49 cm, respectively.ConclusionThis study highlights the complexity and 3D nature of the levator hiatus and pelvic floor muscles. Investigators have previously assumed that the plane of minimal dimensions of the hiatus can be measured in a flat plane, however, the 3D nature of the hiatus means that the true levator hiatus occupies a warped (non‐Euclidean) plane. Hiatal measurements on Valsalva may be subject to systematic error if performed in a single section, i.e. using a flat (Euclidean) plane. Copyright © 2010 ISUOG. Published by John Wiley & Sons, Ltd.
Hospitalization, Frequency of Interventions, and Quality of Life after Endoscopic, Surgical, or Conservative Treatment in Patients with Chronic Pancreatitis
Authors: Rutter Karoline , Ferlitsch A. , Sautner T. , Püspök A. , Götzinger P. , Gangl A. , Schindl M. 
Published: July 2010

AbstractObjectivePatients with chronic pancreatitis usually have a long and debilitating history of disease with frequent hospital admissions, episodes of intractable pain and multiple interventions. The sequences of treatment at initial presentation, endoscopy, surgery, or conservative treatment may affect the time course and admissions needed for disease control, thereby determining quality of life and overall outcome.MethodsA total of 292 patients with initial endoscopic, surgical, or conservative pharmacological treatment were retrospectively analyzed regarding frequency of interventions, days in hospital, symptom‐free intervals, morbidity, and mortality. Quality of life (QoL) at the latest follow‐up was measured by two standardized quality of life questionnaires (EORTC C30 and PAN26).ResultsEndoscopic treatment was initially performed in 150 (51.4%) patients, whereas 99 (33.9%) underwent surgery and 43 (14.7%) patients were treated conservatively at their initial presentation. Patients who underwent surgery had a significantly shorter time in the hospital (25.3 ± 24.6, 34.4 ± 35.1, 61.1 ± 37.9;P< 0.001), fewer subsequent therapies (0.43 ± 1.0, 2.1 ± 2.4, 3.1 ± 3.0;P≤ 0.001), and a longer relapse‐free interval (P= 0.004) compared with endoscopically treated patients. The overall complication rate was 32% both after surgery and endoscopy. Infectious‐related complications occurred more often after surgical treatment (P≤ 0.001), whereas patients after endoscopic intervention developed acute or chronic pancreatitis or pseudocyst formation (P= 0.023).ConclusionsPatients who undergo surgery as their initial treatment for chronic pancreatitis require less consecutive interventions, a shorter hospital stay, and have a better quality of life compared with any other treatment. Surgery should therefore be considered early for the treatment of chronic pancreatitis, when endoscopic or conservative treatment fails and patients require further intervention.
Long‐Term Results of Esophagogastric Devascularization and Splenectomy Associated with Endoscopic Treatment in Schistosomal Portal Hypertension
Authors: Makdissi Fabio Ferrari , Herman Paulo , Pugliese Vincenzo , de Cleva Roberto , Saad William Abrão , Cecconello Ivan , D’Albuquerque Luiz Augusto Carneiro 
Published: July 2010

AbstractBackgroundEsophagogastric devascularization and splenectomy (EGDS) is the most performed operation for prophylaxis of esophageal varices bleeding recurrence in hepatosplenic schistosomiasis. Lower rebleeding rates are obtained through the association of postoperative endoscopic treatment; however, there is a dearth of studies showing long‐term results.MethodsClinical, laboratory, and endoscopic data of 97 patients submitted to EGDS with at least 5 years of follow‐up, were analyzed.ResultsThe mean follow‐up was 116.4 months. Bleeding recurrence occurred in 24.7% of patients; however, this percentage was 14.6% when only variceal hemorrhage was considered. Bleeding recurrence occurred in four patients even after endoscopic evaluation demonstrated esophageal varices eradication. In the late follow‐up we observed normalization of anemia, leukopenia, thrombocytopenia, hyperbilirubinemia, and a prothrombin activity time increase. No clinical or laboratory hepatic insufficiency was observed.ConclusionsThe EGDS procedure with postoperative endoscopic treatment led to good clinical results and avoided hemorrhagic recurrence in 75.3% of schistosomal patients. There was improvement of laboratory measures of hepatic function, as well as correction of hypersplenism. Variceal hemorrhagic recurrence may occur even when esophageal varices eradication is reached.
Compartment Surgery in Treatment Strategies for Retroperitoneal Sarcomas: A Single‐center Experience
Authors: Santos Carlos Eduardo Rodrigues , Correia Mauro Monteiro , Thuler Luiz Claudio Santos , Rosa Bruno Rodrigues , Accetta Antonio , de Almeida Dias Jurandir , de Mello Eduardo Linhares Riello 
Published: July 2010

AbstractBackgroundRetroperitoneal sarcomas (RPS) are rare tumors and radical surgery is still the only curative treatment. We aim to estimate postoperative morbidity and mortality and identify significant prognostic factors for survival of patients with RPS and then evaluate the effect of en bloc resection on survival.MethodsThis was a retrospective follow‐up study of 91 patients with RPS who underwent surgery at the Section of Abdominopelvic Surgery of the National Cancer Institute‐Brazil (INCA) between June 1992 and January 2008. Overall and 2‐, 5‐, and 10‐year disease‐free survival rates were calculated and univariate and Cox multivariate analyses were performed.ResultsThe most common complaints were abdominal pain and mass. Resection was possible in 83.5% and curative resection in 55.3%. Six patients died within the postoperative period (mortality = 6.6%) and 28 had complications (30.8%). Leiomyosarcomas and liposarcomas predominated, as well as G3. The median tumor diameter was 20.5 cm. There were 124 organs resected in association, with only 42 proven invaded. The 5‐year overall survival and disease‐free survival rates were 32.0 and 36.8%, respectively. Cell differentiation, curative or palliative resection, blood transfusion, and re‐resection were significant variables. Compartment surgery had no impact on survival, but it increased the duration of surgery, the need for blood transfusion, and overall morbidity.ConclusionsThis study suggests that early diagnosis and curative resection of retroperitoneal sarcomas can improve long‐term survival. Adjacent organs with evidence of direct invasion must be removed en bloc; others should be spared.
Evaluation of Need for Operative Intervention in Blunt Splenic Injury: Intraperitoneal Contrast Extravasation has an Increased Probability of Requiring Operative Intervention
Authors: Fu Chih‐Yuan , Wu Shih‐Chi , Chen Ray‐Jade , Chen Yung‐Fang , Wang Yu‐Chun , Huang Hung‐Chang , Huang Jui‐Chien , Lu Chih‐Wei , Lin Wei‐Ching 
Published: July 2010

AbstractBackgroundAngioembolization is an effective adjunct to the management of blunt splenic injuries (BSI) that are not surgically treated. However, in some cases patients are unable to undergo angioembolization due to changes in their hemodynamic condition. In this study we attempt to define the characteristics of patients who need angioembolization in high‐grade BSI.MethodsWe retrospectively reviewed the charts of patients with BSI between January 2004 and June 2008. Patients with contrast extravasation (CE) on computed tomography (CT) scan were enrolled. The demographics, Injury Severity Score (ISS), Abbreviated Injury Scale (AIS), the amount of blood transfused, and the type of CE were analyzed.ResultsA total of 69 patients were enrolled. Patients with intraperitoneal CE in BSI required a higher rate of immediate operation due to changed hemodynamics. Furthermore, these patients displayed higher ISS and higher blood transfusion amounts.ConclusionsIn BSI patients, intraperitoneal CE is associated with a higher possibility of requiring surgical intervention. Early surgical intervention should be considered in BSI patients with intraperitoneal CE or with ISS ≥ 25.
Youth ReACT for Social Change: A Method for Youth Participatory Action Research
Authors: Foster-Fishman Pennie G. , Law Kristen M. , Lichty Lauren F. , Aoun Christina 
Published: July 2010

AbstractAlthough participatory action research has become an increasingly popular method with youth, involving them in problem identification, analysis, intervention, and/or feedback, few PAR projects tend to involve youth in all of these phases—particularly the data analysis phase. Yet involvement in the data analysis phase of a research effort can help to promote critical awareness of the targeted issues, potentially increasing the effectiveness of subsequent PAR stages. In addition, although many YPAR projects aim to promote the critical consciousness of their youth participants, some projects struggle to promote this awareness, often because the methods used are not well matched to the developmental needs of their participants. In this paper we present the ReACT Method, a PAR approach specifically designed to promote local knowledge production and critical consciousness by engaging youth in the problem identification, data analysis, and feedback stages of research. Given the lack of attention in the literature to the methods used for engaging youth in these processes, we provide detailed descriptions of the methods we developed to engage youth in problem identification and qualitative data analysis.
13C‐NMR Regioisomeric Analysis of EPA and DHA in Fish Oil Derived Triacylglycerol Concentrates
Authors: Suárez Erick Reyes , Mugford Paul F. , Rolle Alfred J. , Burton Ian W. , Walter John A. , Kralovec Jaroslav A. 
Published: July 2010

AbstractThe regio‐isomeric distribution of the omega‐3 polyunsaturated fatty acids (PUFA) cis‐5,8,11,14,17‐eicosapentaenoic acid (EPA) and cis‐4,7,10,13,16,19‐docosahexaenoic acid (DHA) in the triacylglycerols (TAG) of anchovy/sardine fish oil was determined by 13C nuclear magnetic resonance (NMR) analysis under quantitative conditions. From the measurements of sn‐1,3 and sn‐2 carbonyl peak areas it was established that EPA was mainly located in the sn‐1,3 positions, whereas DHA primarily occupied the sn‐2 position. Reconstituted TAG prepared by Candida antarctica lipase‐B (CALB) glycerolysis of the ethyl ester (EE) or the free fatty acid (FFA) forms of anchovy/sardine fish oil, displayed a different pattern: EPA was equally distributed, while DHA was preferentially attached to the sn‐1,3 positions. TAG concentrates of varying EPA and DHA molar fractions were prepared by CALB‐catalyzed glycerolysis of the corresponding EE and FFA. 13C‐NMR analysis of the purified products revealed a lack of CALB regioselectivity for EPA and a slight sn‐1,3 regioselectivity for DHA. Since this pattern was observed in all cases of this study, it was concluded that the lipase regioselectivity during TAG synthesis is independent of both the acyl donor type (carboxylic acid or ester) and the fatty acid content of the oil substrate.
Antioxidant responses to an acute ultra-endurance exercise: impact on DNA stability and indications for an increased need for nutritive antioxidants in the early recovery phase
Authors: Neubauer Oliver , Reichhold Stefanie , Nics Lukas , Hoelzl Christine , Valentini Judit , Stadlmayr Barbara , Knasmüller Siegfried , Wagner Karl-Heinz 
Published: July 2010

Antioxidant requirements have neither been defined for endurance nor been defined for ultra-endurance athletes. To verify whether an acute bout of ultra-endurance exercise modifies the need for nutritive antioxidants, we aimed (1) to investigate the changes of endogenous and exogenous antioxidants in response to an Ironman triathlon; (2) to particularise the relevance of antioxidant responses to the indices of oxidatively damaged blood lipids, blood cell compounds and lymphocyte DNA and (3) to examine whether potential time-points of increased susceptibility to oxidative damage are associated with alterations in the antioxidant status. Blood that was collected from forty-two well-trained male athletes 2 d pre-race, immediately post-race, and 1, 5 and 19 d later was sampled. The key findings of the present study are as follows: (1) Immediately post-race, vitamin C, α-tocopherol, and levels of the Trolox equivalent antioxidant capacity, the ferric reducing ability of plasma and the oxygen radical absorbance capacity (ORAC) assays increased significantly. Exercise-induced changes in the plasma antioxidant capacity were associated with changes in uric acid, bilirubin and vitamin C. (2) Significant inverse correlations between ORAC levels and indices of oxidatively damaged DNA immediately and 1 d post-race suggest a protective role of the acute antioxidant responses in DNA stability. (3) Significant decreases in carotenoids and γ-tocopherol 1 d post-race indicate that the antioxidant intake during the first 24 h of recovery following an acute ultra-endurance exercise requires specific attention. Furthermore, the present study illustrates the importance of a diversified and well-balanced diet to maintain a physiological antioxidant status in ultra-endurance athletes in reference to recommendations.
Exchange Rate Regimes and Independent Central Banks: A Correlated Choice of Imperfectly Credible Institutions
Authors: Bodea Cristina 
Published: July 2010

AbstractTheory and empirical evidence show that low inflation is a precondition for economic growth. Independent central banks and fixed exchange rates are institutional mechanisms that help keep inflation low by lending monetary policy credibility to governments. However, the two institutions are commonly analyzed as substitutes that tie the hands of inflation prone governments. Thus, the literature has difficulties describing why governments would adopt both institutions and the interaction between them. This paper presents a model that allows policymakers the simultaneous choice of monetary institutions and shows that imperfectly credible institutions will overlap: when exchange rates are fixed but adjustable and central bank independence is not fully ascertainable, governments choose both institutions. More generally, the paper generates hypotheses about the conditions that make fixed exchange rates and independent central banks complements or substitutes, thus contributing to an explanation of the diversity of global monetary institutions in the post–Bretton Woods period.
First report of larval stages ofFasciola hepaticain a wild population ofPseudosuccinea columellafrom Cuba and the Caribbean
Authors: Gutiérrez A. , Vázquez A.A. , Hevia Y. , Sánchez J. , Correa A.C. , Hurtrez-Boussès S. , Pointier J.-P. , Théron A. 
Published: July 2010

AbstractA wild population of the lymnaeid snailPseudosuccinea columellainfected by larval stages ofFasciola hepaticawas discovered in the Pinar del Río Province, Cuba. One of 100 snails was infected in a rice culture field. This is the first time this species has been found acting as intermediate host ofF. hepaticaunder natural conditions, not only for Cuba but also for the Caribbean area.
Why is there no gender in the English School?
Authors: BLANCHARD ERIC M. 
Published: July 2010

AbstractWhy has English School theory, even as it has been re-imagined as critical international society theory, ignored the workings of gender in international politics? This article stages an encounter between the English School and feminists in International Relations (IR), first demonstrating the broad compatibility of the two approaches. I argue that to conduct a conversation between English School and IR feminist approaches, it is necessary to reconstruct the English School's three traditions – Realist, Rationalist, and Revolutionist – so as to allow a greater role for gender as a category of analysis. I then review the work of two key English School scholars, Hedley Bull and Barry Buzan with this reconstruction in mind. Finally, I argue that IR theorists who have participated in the recent English School revival should consider integrating gender into its theoretical and research agenda, and show several examples of how a hybrid approach can be brought to bear on the expansion of international society, diplomacy, and human rights.
Positive-entropy integrable systems and the Toda lattice, II
Authors: BUTLER LEO T. 
Published: July 2010

AbstractThis paper constructs completely integrable convex Hamiltonians on the cotangent bundle of certain k bundles over l. A central role is played by the Lax representation of a Bogoyavlenskij–Toda lattice. The classification of these systems, up to iso-energetic topological conjugacy, is related to the classification of abelian groups of Anosov toral automorphisms by their topological entropy function.
Catalan loops
Authors: LONG LING , SMITH JONATHAN D. H. 
Published: July 2010

AbstractMotivated by a problem from number theory about the relationship between Fermat curves and modular curves, a new class of loops is introduced, the Catalan loops. In the number-theoretic context, these loops turn out to be abelian precisely when the Fermat curves and modular curves coincide. General Catalan loops arise on certain transversals to diagonal subgroups in special linear groups over rings with a topologically nilpotent element. The transversals consist of products of certain affine shears. In a Catalan loop, the multiplication and right division are given by rational functions. The left division is algebraic, corresponding to a quadratic irrationality. The left division embodies generating functions for the Catalan numbers. Structurally, Catalan loops are shown to be residually nilpotent.
Serotype distribution of Streptococcus pneumoniae causing invasive disease in the Republic of Ireland
Authors: VICKERS I. , FITZGERALD M. , MURCHAN S. , COTTER S. , O'FLANAGAN D. , CAFFERKEY M. , HUMPHREYS H. 
Published: July 2010

SUMMARYThe 7-valent pneumococcal conjugate vaccine (PCV7) was included in the routine infant immunization schedule in Ireland in September 2008. We determined the serotype of 977 S. pneumoniae isolates causing invasive disease between 2000–2002 and 2007–2008, assessed for the presence of the recently described serotype 6C and determined the susceptibility of isolates during 2007–2008 to penicillin and cefotaxime. Serotype 14 was the most common serotype during both periods and 7·7% of isolates previously typed as serotype 6A were serotype 6C. During 2000–2002 and 2007–2008, PCV7 could potentially have prevented 85% and 74% of invasive pneumococcal disease in the target population (i.e. children aged <2 years), respectively. The level of penicillin non-susceptibility was 17% in 2007–2008. Ongoing surveillance of serotypes is required to determine the impact of PCV7 in the Irish population and to assess the potential of new vaccines with expanded valency.