240 research outputs found
Heterotopic Ossification Causing Radiculopathy after Lumbar Total Disc Arthroplasty
To date, no reports have presented radiculopathy secondary to heterotopic ossification following lumbar total disc arthroplasty. The authors present a previously unpublished complication of lumbar total disk arthroplasty (TDA) secondary to heterotopic ossification (HO) in the spinal canal, and they propose a modification to the McAfee classification of HO. The patient had undergone an L5/S1 lumbar TDA two years prior due to discogenic back pain. His preoperative back pain was significantly relieved, but he developed new, atraumatic onset radiculopathy. Radiographs and a computed tomography myelogram revealed an implant malposition posteriorly with heterotopic bone formation in the canal, causing an impingement of the traversing nerve root. Revision surgery was performed with implant extraction, L5/S1 anterior lumbar interbody fusion, supplemental posterior decompression, and pedicle screw fixation. The patient tolerated the procedure well, with complete resolution of the radicular leg pain. At a two-year follow up, the patient had a solid fusion without subsidence or recurrence of heterotopic bone. This case represents a novel pattern of heterotopic ossification, and it describes a previously unreported cause for implant failure in lumbar disc replacement surgery-reinforcing the importance of proper intraoperative component positioning. We propose a modification to the existing McAfee classification of HO after TDA with the addition of Class V and VI HO
Measurement of one-particle correlations and momentum distributions for trapped 1D gases
van Hove's theory of scattering of probe particles by a macroscopic target is
generalized so as to relate the differential cross section for atomic ejection
via stimulated Raman transitions to one-particle momentum-time correlations and
momentum distributions of 1D trapped gases. This method is well suited to
probing the longitudinal momentum distributions of 1D gases in situ, and
examples are given for bosonic and fermionic atoms.Comment: 4 pages, 2 .eps figure
Stationary solutions of the one-dimensional nonlinear Schroedinger equation: I. Case of repulsive nonlinearity
All stationary solutions to the one-dimensional nonlinear Schroedinger
equation under box and periodic boundary conditions are presented in analytic
form. We consider the case of repulsive nonlinearity; in a companion paper we
treat the attractive case. Our solutions take the form of stationary trains of
dark or grey density-notch solitons. Real stationary states are in one-to-one
correspondence with those of the linear Schr\"odinger equation. Complex
stationary states are uniquely nonlinear, nodeless, and symmetry-breaking. Our
solutions apply to many physical contexts, including the Bose-Einstein
condensate and optical pulses in fibers.Comment: 11 pages, 7 figures -- revised versio
The Consolidation of the White Southern Congressional Vote
This article explores the initial desertion and continued realignment of about one-sixth of the white voters in the South who, until 1994, stood by Democratic congressional candidates even as they voted for Republican presidential nominees. Prior to 1994, a sizable share of the white electorate distinguished between Democratic congressional and presidential candidates; since 1994 that distinction has been swept away. In 1992, a majority of white southern voters was casting their ballot for the Democratic House nominee; by 1994, the situation was reversed and 64 percent cast their ballot for the Republican. Virtually all categories of voters increased their support of Republican congressional candidates in 1994 and the following elections further cement GOP congressional support in the South. Subsequent elections are largely exercises in partisanship, as the congressional votes mirror party preferences. Republicans pull nearly all GOP identifiers, most independents, and a sizeable minority of Democratic identifiers. Democrats running for Congress no longer convince voters that they are different from their party’s presidential standard bearers—a group that has consistently been judged unacceptable to overwhelming proportions of the southern white electorate.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline
Relaxing Constraints as a Conservation Policy
Eco-entrepreneurs in developing countries are often subject to market or institutional constraints, e.g. via credit rationing or missing markets. Conservation interventions which relax constraints may be both cost-effective and poverty reducing. A simulation using data from an intervention in Madagascar to relax the technological constraints of forest honey production investigates this possibility. Cost-effectively achieving dual environment-development goals is shown to depend on the severity of constraints, relative prices and, importantly, the nature of technology. Success is more likely for technologies exhibiting close to constant returns to scale or high input complementarity. Forest honey does not meet these requirements, whereas sustainable forest management may well do. Ultimately, where market or institutional constraints are present, knowledge of the recipient technology is required for more informed, efficient and perhaps, more politically-acceptable conservation policy
Reducing repeat pregnancies in adolescence: applying realist principles as part of a mixed-methods systematic review to explore what works, for whom, how and under what circumstances
BACKGROUND: Previous research has demonstrated emotional, psychological and educational harm to young mothers following unintended conceptions. The UK has one of the highest rates of pregnancies in adolescence in Western Europe with a high proportion of these being repeat pregnancies, making it a topic of interest for public health policy makers, and health and social care practitioners. As part of a wider mixed-methods systematic review, realist principles were applied to synthesise evidence about interventions aiming to reduce repeat pregnancies in adolescence.METHODS: A multi-streamed, mixed-methods systematic review was conducted searching 11 major electronic databases and 9 additional databases from 1995 onwards, using key terms such as pregnancy, teen or adolescent. The principles of realist synthesis were applied to all included literature to uncover theories about what works, for whom, how and in what context. Initial theory areas were developed through evidence scoping, group discussion by the authors and stakeholder engagement to uncover context + mechanism = outcome (CMO) configurations and related narratives.RESULTS: The searches identified 8,664 documents initially, and 403 in repeat searches, filtering to 81 included studies, including qualitative studies, randomised controlled trials, quantitative studies and grey literature. Three CMO configurations were developed. The individual experiences of young mothers' triggered self-efficacy, notions of perceived risks, susceptibility and benefits of pregnancy, resulting in the adolescent taking control of their fertility and sexual encounters. The choice between motherhood and other goals triggered notions of motivations, resulting in the adolescent managing their expectations of motherhood and controlling their fertility and sexual encounters. Barriers and facilitators to accessing services triggered notions of connectedness and self-determination; resulting in interventions that are tailored so they are relevant to young persons, and improve access to services and engagement with the issue of pregnancy in adolescence.CONCLUSIONS: Pregnancy in adolescence is a complex issue with many factors to consider. The conceptual platform described here could help guide policy makers and professionals towards a number of areas that need to be attended to in order to increase the likelihood of an intervention working to prevent rapid repeat pregnancy in adolescence.TRIAL REGISTRATION: PROSPERO CRD42012003168
Student Attitudes Contribute to the Effectiveness of a Genomics CURE
The Genomics Education Partnership (GEP) engages students in a course-based undergraduate research experience (CURE). To better understand the student attributes that support success in this CURE, we asked students about their attitudes using previously published scales that measure epistemic beliefs about work and science, interest in science, and grit. We found, in general, that the attitudes students bring with them into the classroom contribute to two outcome measures, namely, learning as assessed by a pre- and postquiz and perceived self-reported benefits. While the GEP CURE produces positive outcomes overall, the students with more positive attitudes toward science, particularly with respect to epistemic beliefs, showed greater gains. The findings indicate the importance of a student\u27s epistemic beliefs to achieving positive learning outcomes
Prostate-specific antigen testing accuracy in community practice
BACKGROUND: Most data on prostate-specific antigen (PSA) testing come from urologic cohorts comprised of volunteers for screening programs. We evaluated the diagnostic accuracy of PSA testing for detecting prostate cancer in community practice. METHODS: PSA testing results were compared with a reference standard of prostate biopsy. Subjects were 2,620 men 40 years and older undergoing (PSA) testing and biopsy from 1/1/95 through 12/31/98 in the Albuquerque, New Mexico metropolitan area. Diagnostic measures included the area under the receiver-operating characteristic curve, sensitivity, specificity, and likelihood ratios. RESULTS: Cancer was detected in 930 subjects (35%). The area under the ROC curve was 0.67 and the PSA cutpoint of 4 ng/ml had a sensitivity of 86% and a specificity of 33%. The likelihood ratio for a positive test (LR+) was 1.28 and 0.42 for a negative test (LR-). PSA testing was most sensitive (90%) but least specific (27%) in older men. Age-specific reference ranges improved specificity in older men (49%) but decreased sensitivity (70%), with an LR+ of 1.38. Lowering the PSA cutpoint to 2 ng/ml resulted in a sensitivity of 95%, a specificity of 20%, and an LR+ of 1.19. CONCLUSIONS: PSA testing had fair discriminating power for detecting prostate cancer in community practice. The PSA cutpoint of 4 ng/ml was sensitive but relatively non-specific and associated likelihood ratios only moderately revised probabilities for cancer. Using age-specific reference ranges and a PSA cutpoint below 4 ng/ml improved test specificity and sensitivity, respectively, but did not improve the overall accuracy of PSA testing
Three new pancreatic cancer susceptibility signals identified on chromosomes 1q32.1, 5p15.33 and 8q24.21.
Genome-wide association studies (GWAS) have identified common pancreatic cancer susceptibility variants at 13 chromosomal loci in individuals of European descent. To identify new susceptibility variants, we performed imputation based on 1000 Genomes (1000G) Project data and association analysis using 5,107 case and 8,845 control subjects from 27 cohort and case-control studies that participated in the PanScan I-III GWAS. This analysis, in combination with a two-staged replication in an additional 6,076 case and 7,555 control subjects from the PANcreatic Disease ReseArch (PANDoRA) and Pancreatic Cancer Case-Control (PanC4) Consortia uncovered 3 new pancreatic cancer risk signals marked by single nucleotide polymorphisms (SNPs) rs2816938 at chromosome 1q32.1 (per allele odds ratio (OR) = 1.20, P = 4.88x10 -15), rs10094872 at 8q24.21 (OR = 1.15, P = 3.22x10 -9) and rs35226131 at 5p15.33 (OR = 0.71, P = 1.70x10 -8). These SNPs represent independent risk variants at previously identified pancreatic cancer risk loci on chr1q32.1 ( NR5A2), chr8q24.21 ( MYC) and chr5p15.33 ( CLPTM1L- TERT) as per analyses conditioned on previously reported susceptibility variants. We assessed expression of candidate genes at the three risk loci in histologically normal ( n = 10) and tumor ( n = 8) derived pancreatic tissue samples and observed a marked reduction of NR5A2 expression (chr1q32.1) in the tumors (fold change -7.6, P = 5.7x10 -8). This finding was validated in a second set of paired ( n = 20) histologically normal and tumor derived pancreatic tissue samples (average fold change for three NR5A2 isoforms -31.3 to -95.7, P = 7.5x10 -4-2.0x10 -3). Our study has identified new susceptibility variants independently conferring pancreatic cancer risk that merit functional follow-up to identify target genes and explain the underlying biology
- …