bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of Nonmodifiable Risk Factors for Intracranial Aneurysm Rupture in a Large, Retrospective Cohort
Authors: Amenta Peter S. , Yadla Sanjay , Campbell Peter G. , Maltenfort Mitchell G. , Dey Saugat , Ghosh Sayantani , Ali Muhammad S. , Jallo Jack I. , Tjoumakaris Stavropoula I. , Gonzalez L. Fernando , Dumont Aaron S. , Rosenwasser Robert H. , Jabbour Pascal M. 
Published: October 2011

Abstract

Background:
The risk factors predictive of intracranial aneurysm rupture remain incompletely defined.

Objective:
To examine the association between various nonmodifiable risk factors and aneurysm rupture in a large cohort of patients evaluated at a single institution.

Methods:
A retrospective analysis of patients admitted to a cerebrovascular facility between January 2006 and 2010 with a primary diagnosis of cerebral aneurysm. Aneurysms were divided into 2 groups: unruptured or ruptured. The dome diameter, aspect ratio (AR), location, sidedness, neck morphology, and multiplicity were entered into a central database. A full model was constructed, and a systematic removal of the least significant variables was performed in a sequential fashion until only those variables reaching significance remained.

Results:
We identified 2347 patients harboring 5134 individual aneurysms, of which 34.90% were ruptured and 65.09% were unruptured. On admission, 25.89% of aneurysms with a dome diameter &lt;10 mm and 58.33% of aneurysms with a dome &gt;10 mm were ruptured (P &lt; .001). Of aneurysms with an AR &gt;1.6, 52.44% presented following a rupture (P &lt; .001). The highest incidence of rupture (69.21%) was observed in aneurysms with an AR &gt;1.6, dome diameter &lt;10 mm, and a deviated neck. Deviated neck-type aneurysms had a significantly greater incidence of rupture than classical necktype aneurysms (P &lt; .001).

Conclusion:
An AR &gt;1.6, dome diameter &gt;10 mm, a deviated neck, and right-sidedness are independently associated with aneurysm rupture.
ε-Aminocaproic Acid in Angiographically Negative Subarachnoid Hemorrhage Patients Is Safe: A Retrospective Review of 83 Consecutive Patients
Authors: Hui Ferdinand K. , Schuette Albert J. , Lieber Michael , Spiotta Alejandro M. , Moskowitz Shaye I. , Barrow Daniel L. , Cawley C. Michael 
Published: October 2011

AbstractBackground:ε-Aminocaproic acid (EACA) has been used to reduce the rate of cerebral aneurysm rerupture before definitive treatment. In centers administering EACA to patients with a subarachnoid hemorrhage (SAH), patients eventually diagnosed with angiographically negative subarachnoid hemorrhage (ANSAH) may also initially receive EACA, perhaps placing them at increased risk for ischemic complications.Objective:To evaluate the effect of short-term EACA on outcomes and secondary measures in patients with ANSAH.Methods:We conducted a retrospective study of 454 consecutive SAH patients over a 2-year period under a current protocol for EACA use. Patients were excluded if a source for the SAH was discovered, yielding a total of 83 ANSAH patients. The patients were assigned to groups that did or did not receive EACA. The primary end points of the study were ischemic complications, pulmonary emboli, vasospasm, ventriculoperitoneal shunting rates, and outcomes.Results:Statistical analysis yielded no significant difference between the 2 arms with respect to any of the end points: vasospasm (P = .65), deep vein thrombosis (P = .51), pulmonary embolism (P = 1.0), stroke (P = 1.0), myocardial infarction (P = 1.0), and ventriculoperitoneal shunt (P = .57). There was no statistically significant outcome difference using the modified Rankin Scale (P = .30).Conclusion:Short-term (&lt;72 hour) application of EACA does not result in an increase in adverse events in patients with ANSAH.
Multiparametric analysis of magnetic resonance images for glioma grading and patient survival time prediction
Authors: Garzón Benjamín , Emblem Kyrre E , Mouridsen Kim , Nedregaard Baard , Due-Tønnessen Paulina , Nome Terje , Hald John K , Bjørnerud Atle , Håberg Asta K , Kvinnsland Yngve 
Published: October 2011

Background A systematic comparison of magnetic resonance imaging (MRI) options for glioma diagnosis is lacking. Purpose To investigate multiple MR-derived image features with respect to diagnostic accuracy in tumor grading and survival prediction in glioma patients. Material and Methods T1 pre- and post-contrast, T2 and dynamic susceptibility contrast scans of 74 glioma patients with histologically confirmed grade were acquired. For each patient, a set of statistical features was obtained from the parametric maps derived from the original images, in a region-of-interest encompassing the tumor volume. A forward stepwise selection procedure was used to find the best combinations of features for grade prediction with a cross-validated logistic model and survival time prediction with a cox proportional-hazards regression. Results Presence/absence of enhancement paired with kurtosis of the FM (first moment of the first-pass curve) was the feature combination that best predicted tumor grade (grade II vs. grade III-IV; median AUC = 0.96), with the main contribution being due to the first of the features. A lower predictive value (median AUC = 0.82) was obtained when grade IV tumors were excluded. Presence/absence of enhancement alone was the best predictor for survival time, and the regression was significant ( P < 0.0001). Conclusion Presence/absence of enhancement, reflecting transendothelial leakage, was the feature with highest predictive value for grade and survival time in glioma patients.
Diagnosis of lymph node metastasis in uterine cervical cancer: usefulness of computer-aided diagnosis with comprehensive evaluation of MR images and clinical findings
Authors: Kim Mi-hyun , Kim Jeong Kon , Lee Youngjoo , Park Bum-Woo , Lee Chang Kyung , Kim Namkug , Cho Gyunggoo , Choi Hyuck Jae , Cho Kyoung-Sik 
Published: October 2011

Background Lymph node (LN) status is an important parameter for determining the treatment strategy and for predicting the prognosis for patients with uterine cervical cancer. Computer-aided diagnosis (CAD) can be feasible for differentiating metastatic from non-metastatic lymph nodes in patients with uterine cervical cancer Purpose To determine the usefulness of CAD that comprehensively evaluates MR images and clinical findings for detecting LN metastasis in uterine cervical cancer. Material and Methods In 680 LNs from 143 patients who underwent radical hysterectomy for uterine cervical cancer, the CAD system using the Bayesian classifier estimated the probability of metastasis based on MR findings and clinical findings. We compared the diagnostic accuracy for detecting metastatic LNs in the CAD and MR findings. Results Metastasis was diagnosed in 70 (12%) LNs from 34 (24%) patients. The area under ROC curves of CAD (0.924) was greater than those of the mean ADC (0.854), minimum ADC (0.849), maximum ADC (0.827), short-axis diameter (0.856) and long-axis diameter (0.753) ( P < 0.05). The specificity and accuracy of the CAD (86%, 86%) were greater than those of the mean ADC (77%, 77%), maximum ADC (77%, 77%), minimum ADC (68%, 70%), and short-axis diameter (65%, 67%) ( P < 0.05). Conclusion CAD system can improve the diagnostic performance of MR for detecting metastatic LNs in uterine cervical cancer.
Competition in the NHS: A Provider Perspective
Authors: Frosini Francesca , Dixon Anna , Robertson1 Ruth 
Published: October 2011

Objective To analyse how competition is experienced and characterized by NHS and independent sector acute care providers in the English National Health Service (NHS). Methods Semi-structured interviews with 49 senior staff in 15 NHS trusts and independent sector providers between November 2008 and April 2009, in England. Results The market was predominantly defined based on geographical proximity. Competition was mainly on the periphery of catchment areas but markets were differentiated based on the scope and type of services. Niche providers, specialist hospitals and tertiary centres did not directly compete with district general hospital-type providers. Competitors were increasingly primary and community care providers, while there was little perceived threat from the private sector. There were many examples of how different providers (both NHS and independent sector) were co-operating and collaborating. Patients and general practitioners (GPs) appeared to be loyal to local providers. Conclusion The providers' view of the market and the relevance of historical relationships and loyalties suggest fine grained variations in competition which is consistent with a relational rather than structural approach to competition. Also the evidence on embeddedness of relationships implies that collaboration might be a strong lever for quality improvement locally. Finally, some of the agreements found might be deemed in breach of the rules of competition but they may well be in the interests of patients and taxpayers, with implications for regulation in publicly funded health care systems.
‘Animateurs’ and Animation: What Makes a Good Commissioning Manager?
Authors: Checkland Kath , Snow Stephanie , McDermott Imelda , Harrison Stephen , Coleman Anna 
Published: October 2011

Objectives To examine the managerial behaviours adopted by commissioning managers in English primary care trusts (PCTs), and to explore the impact of these behaviours. Methods Qualitative case studies were undertaken in four PCTs, focusing on staff engaged in the commissioning of hospital services. Both formal and informal observation were undertaken (150 hours), and 41 in-depth interviews conducted with managers and general practitioners (GPs). Results Managers adopted many managerial behaviours familiar from the literature, including sharing information, and networking inside and outside the organization. Multiple organizational layers and unclear decisionmaking processes hindered this activity. In addition, some managers with responsibility for facilitating practice-based commissioning (PbC) adopted a managerial mode that we have called being an ‘animateur’. This approach involved the active management of disparate groups of people over whom the manager had no authority, and appeared to be a factor in determining success. It was facilitated by managerial autonomy and was more prevalent where managers were seen to have legitimacy. Some organizational practices appeared to inhibit its development. Conclusions From 2012/13 it is planned that GPs will be taking more responsibility for commissioning in the English NHS. This research suggests that managers of the new commissioning organizations will require a deep and contextualized understanding of the NHS and that it is important that organizational processes do not inhibit managerial behaviour. Legitimacy may be an issue in contexts were managers are automatically transferred from their existing appointments.
Empirical Evaluation Reveals Best Fit of a Logistic Mutation Model for Human Y-Chromosomal Microsatellites
Authors: Jochens Arne , Caliebe Amke , Rösler Uwe , Krawczak Michael 
Published: October 2011

AbstractThe rate of microsatellite mutation is dependent upon both the allele length and the repeat motif, but the exact nature of this relationship is still unknown. We analyzed data on the inheritance of human Y-chromosomal microsatellites in father–son duos, taken from 24 published reports and comprising 15,285 directly observable meioses. At the six microsatellites analyzed (DYS19, DYS389I, DYS390, DYS391, DYS392, and DYS393), a total of 162 mutations were observed. For each locus, we employed a maximum-likelihood approach to evaluate one of several single-step mutation models on the basis of the data. For five of the six loci considered, a novel logistic mutation model was found to provide the best fit according to Akaike’s information criterion. This implies that the mutation probability at the loci increases (nonlinearly) with allele length at a rate that differs between upward and downward mutations. For DYS392, the best fit was provided by a linear model in which upward and downward mutation probabilities increase equally with allele length. This is the first study to empirically compare different microsatellite mutation models in a locus-specific fashion.
A General Mechanistic Model for Admixture Histories of Hybrid Populations
Authors: Verdu Paul , Rosenberg Noah A 
Published: October 2011

AbstractAdmixed populations have been used for inferring migrations, detecting natural selection, and finding disease genes. These applications often use a simple statistical model of admixture rather than a modeling perspective that incorporates a more realistic history of the admixture process. Here, we develop a general model of admixture that mechanistically accounts for complex historical admixture processes. We consider two source populations contributing to the ancestry of a hybrid population, potentially with variable contributions across generations. For a random individual in the hybrid population at a given point in time, we study the fraction of genetic admixture originating from a specific one of the source populations by computing its moments as functions of time and of introgression parameters. We show that very different admixture processes can produce identical mean admixture proportions, but that such processes produce different values for the variance of the admixture proportion. When introgression parameters from each source population are constant over time, the long-term limit of the expectation of the admixture proportion depends only on the ratio of the introgression parameters. The variance of admixture decreases quickly over time after the source populations stop contributing to the hybrid population, but remains substantial when the contributions are ongoing. Our approach will facilitate the understanding of admixture mechanisms, illustrating how the moments of the distribution of admixture proportions can be informative about the historical admixture processes contributing to the genetic diversity of hybrid populations.
Sperm Status Regulates Sexual Attraction in Caenorhabditis elegans
Authors: Morsci Natalia S , Haas Leonard A , Barr Maureen M 
Published: October 2011

Abstract
Mating behavior of animals is regulated by the sensory stimuli provided by the other sex. Sexually receptive females emit mating signals that can be inhibited by male ejaculate. The genetic mechanisms controlling the release of mating signals and encoding behavioral responses remain enigmatic. Here we present evidence of a Caenorhabditis elegans hermaphrodite-derived cue that stimulates male mating-response behavior and is dynamically regulated by her reproductive status. Wild-type males preferentially mated with older hermaphrodites. Increased sex appeal of older hermaphrodites was potent enough to stimulate robust response from mating-deficient pkd-2 and lov-1 polycystin mutant males. This enhanced response of pkd-2 males toward older hermaphrodites was independent of short-chain ascaroside pheromones, but was contingent on the absence of active sperm in the hermaphrodites. The improved pkd-2 male response toward spermless hermaphrodites was blocked by prior insemination or by genetic ablation of the ceh-18-dependent sperm-sensing pathway of the hermaphrodite somatic gonad. Our work suggests an interaction between sperm and the soma that has a negative but reversible effect on a hermaphrodite-derived mating cue that regulates male mating response, a phenomenon to date attributed to gonochoristic species only.
Hyperventilation in Pediatric Resuscitation: Performance in Simulated Pediatric Medical Emergencies
Authors: Niebauer Julia M. , White Marjorie Lee , Zinkan J. Lynn , Youngblood Amber Q. , Tofil Nancy M. 
Published: October 2011

OBJECTIVE:
To examine the hypothesis that pediatric resuscitation providers hyperventilate patients via bag-valve-mask (BVM) ventilation during performance of cardiopulmonary resuscitation (CPR), quantify the degree of excessive ventilation provided, and determine if this tendency varies according to provider type.

METHODS:
A retrospective, observational study was conducted of 72 unannounced, monthly simulated pediatric medical emergencies (“mock codes”) in a tertiary care, academic pediatric hospital. Responders were code team members, including pediatric residents and interns (MDs), respiratory therapists (RTs), and nurses (RNs). All sessions were video-recorded and reviewed for the rate of BVM ventilation, rate of chest compressions, and the team members performing these tasks. The type of emergency, location of the code, and training level of the team leader were also recorded.

RESULTS:
Hyperventilation was present in every mock code reviewed. The mean rate of BVM ventilation for all providers in all scenarios was 40.6 ± 11.8 breaths per minute (BPM). The mean ventilation rates for RNs, RTs, and MDs were 40.8 ± 14.7, 39.9 ± 11.7, and 40.5 ± 10.3 BPM, respectively, and did not differ among providers (P = .94). All rates were significantly higher than the recommended rate of 8 to 20 BPM (per Pediatric Advanced Life Support guidelines, varies with patient age) (P &lt; .001). The mean ventilation rate in cases of isolated respiratory arrest was 44.0 ± 13.9 BPM and was not different from the mean BVM ventilation rate in cases of cardiopulmonary arrest (38.9 ± 14.4 BPM; P = .689).

CONCLUSIONS:
Hyperventilation occurred in simulated pediatric resuscitation and did not vary according to provider type. Future educational interventions should focus on avoidance of excessive ventilation.
Cognitive and Behavioral Outcomes After Early Exposure to Anesthesia and Surgery
Authors: Flick Randall P. , Katusic Slavica K. , Colligan Robert C. , Wilder Robert T. , Voigt Robert G. , Olson Michael D. , Sprung Juraj , Weaver Amy L. , Schroeder Darrell R. , Warner David O. 
Published: October 2011

BACKGROUND:Annually, millions of children are exposed to anesthetic agents that cause apoptotic neurodegeneration in immature animals. To explore the possible significance of these findings in children, we investigated the association between exposure to anesthesia and subsequent (1) learning disabilities (LDs), (2) receipt of an individualized education program for an emotional/behavior disorder (IEP-EBD), and (3) scores of group-administered achievement tests.METHODS:This was a matched cohort study in which children (N = 8548) born between January 1, 1976, and December 31, 1982, in Rochester, Minnesota, were the source of cases and controls. Those exposed to anesthesia (n = 350) before the age of 2 were matched to unexposed controls (n = 700) on the basis of known risk factors for LDs. Multivariable analysis adjusted for the burden of illness, and outcomes including LDs, receipt of an IEP-EBD, and the results of group-administered tests of cognition and achievement were outcomes.RESULTS:Exposure to multiple, but not single, anesthetic/surgery significantly increased the risk of developing LDs (hazard ratio: 2.12 [95% confidence interval: 1.26–3.54]), even when accounting for health status. A similar pattern was observed for decrements in group-administered tests of achievement and cognition. However, exposure did not affect the rate of children receiving an individualized education program.CONCLUSIONS:Repeated exposure to anesthesia and surgery before the age of 2 was a significant independent risk factor for the later development of LDs but not the need for educational interventions related to emotion/behavior. We cannot exclude the possibility that multiple exposures to anesthesia/surgery at an early age may adversely affect human neurodevelopment with lasting consequence.
Alternative Vaccination Schedule Preferences Among Parents of Young Children
Authors: Dempsey Amanda F. , Schaffer Sarah , Singer Dianne , Butchart Amy , Davis Matthew , Freed Gary L. 
Published: October 2011

OBJECTIVE:
Increasing numbers of parents use alternative vaccination schedules that differ from the recommended childhood vaccination schedule for their children. We sought to describe national patterns of alternative vaccination schedule use and the potential “malleability” of parents' current vaccination schedule choices.

METHODS:
We performed a cross-sectional, Internet-based survey of a nationally representative sample of parents of children 6 months to 6 years of age. Bivariate and multivariate analyses determined associations between demographic and attitudinal factors and alternative vaccination schedule use.

RESULTS:
The response rate was 61% (N = 748). Of the 13% of parents who reported following an alternative vaccination schedule, most refused only certain vaccines (53%) and/or delayed some vaccines until the child was older (55%). Only 17% reported refusing all vaccines. In multivariate models, nonblack race and not having a regular health care provider for the child were the only factors significantly associated with higher odds of using an alternative schedule. A large proportion of alternative vaccinators (30%) reported having initially followed the recommended vaccination schedule. Among parents following the recommended vaccination schedule, 28% thought that delaying vaccine doses was safer than the schedule they used, and 22% disagreed that the best vaccination schedule to follow was the one recommended by vaccination experts.

CONCLUSIONS:
More than 1 of 10 parents of young children currently use an alternative vaccination schedule. In addition, a large proportion of parents currently following the recommended schedule seem to be “at risk” for switching to an alternative schedule.
Entrepreneurship Capital and Technical Efficiency: The Role of New Business/Firms as a Conduit of Knowledge Spillovers
Authors: Laborda Castillo Leopoldo , Guasch Jose Luis , Sotelsek Salem Daniel 
Published: October 2011

Abstract
Increasingly, entrepreneurship is being discussed and considered as a source of high economic growth and competitiveness. Agarwal, Audretsch and Sarkar (2010), questioning the underlying assumptions in the traditional framework of the process of creative destruction, provide an alternative conceptual process of creative construction that characterizes the dynamics between entrants and incumbents. Conceptually, this new framework of creative construction can prove quite useful to analyze the impact of countries’ entrepreneurship capital on economic performance and can be a guide for economic policy.
Audretsch and Keilbach (2003), argue that entrepreneurship capital promotes economic performance by serving as a conduit of knowledge spillovers. A Stochastic Frontier Analysis (SFA) approach is applied here to test this hypothesis. In addition, kernel density functions are employed to analyze convergence (or divergence) in the efficiency estimated for individual countries.
The empirical evidence and results here tend to support the Audretsch and Keilbach hypothesis. Specifically, the empirical analysis shows that the rate of expenses on R&D in relation to New Businesses Registered (NBR) has a positive and significant effect in increasing technical efficiency. These factors facilitate the dissemination of existing knowledge, develop entrepreneurship capital, and thus provide the missing link to economic performance—entrepreneurship capital. We also show the trends and dynamics of changes in countries technical efficiency. Policy implications from these findings are presented.