Arrow ribbon graphs

We introduce an additional structure on ribbon graphs, arrow structure. We extend the Bollob\'as-Riordan polynomial to ribbon graph with this structure. The extended polynomial satisfies the contraction-deletion relations and naturally behaves with respect to the partial duality of ribbon graphs. We construct an arrow ribbon graph from a virtual link whose extended Bollob\'as-Riordan polynomial specializes to the arrow polynomial of the virtual link recently introduced by H.Dye and L.Kauffman. This result generalizes the classical Thistlethwaite theorem to the arrow polynomial of virtual links.Comment: to appear in Journal of Knot Theory and Its Ramification

Registration of hard white winter wheat germplasms KS14U6380R5, KS16U6380R10, and KS16U6380R11 with adult plant resistance to stem rust

Resistance to the Ug99 group of races of the stem rust fungus Puccinia graminis f. sp. tritici is limited in winter wheat (Triticum aestivum L.) germplasm adapted to the Great Plains of the United States. Our objective was to generate regionally adapted hard winter wheat germplasm with combinations of adult plant resistance genes that are expected to provide durable resistance. KS14U6380R5 (Reg. no. GP-1043, PI 689115), KS16U6380R10 (Reg. no. GP-1044, PI 689116), and KS16U6380R11 (Reg. no. GP-1045, PI 689117) were derived from backcrosses of the hard white winter wheat germplasm KS05HW14 to the stem rust-resistant Kenyan spring wheat cultivar ‘Kingbird’. KS14U6380R5, KS16U6380R11, and KS16U6380R10 were developed by pedigree selection and were initially evaluated as U6380-11-2R-0A, U6380-210-2R-0A, and U6380-148-4R-2T, respectively. The germplasms were developed by the USDA-ARS and jointly released with the Kansas State University Agricultural Experiment Station. These germplasms provide parents for development of hard winter wheat cultivars with durable resistance to stem rust

Clinical Faculty in the Legal Academy: Hiring, Promotion, and Retention

The Chair of the Association of American Law Schools (AALS) Section on Clinical Legal Education appointed us in 2005 to the Task Force on the Status of Clinicians and the Legal Academy (Task Force) to examine who is teaching in clinical programs and using clinical methodologies in American law schools and to identify the most appropriate models for clinical appointments within the legal academy. Our charges reflected two ongoing concerns: 1) the need to collect valid, reliable, and helpful data that would inform discussions on the breadth of clinical education in the legal academy and the status of clinical educators within the academy; and 2) the need to have a foundation for complex conversations on how American law schools should view and value their clinical teachers. The first primarily describes the present, while the second carries implications for the future

Iatrogenic Spinal Cord Injury Resulting From Cervical Spine Surgery.

STUDY DESIGN: Retrospective cohort study of prospectively collected data. OBJECTIVE: To examine the incidence of iatrogenic spinal cord injury following elective cervical spine surgery. METHODS: A retrospective multicenter case series study involving 21 high-volume surgical centers from the AOSpine North America Clinical Research Network was conducted. Medical records for 17 625 patients who received cervical spine surgery (levels from C2 to C7) between January 1, 2005, and December 31, 2011, were reviewed to identify occurrence of iatrogenic spinal cord injury. RESULTS: In total, 3 cases of iatrogenic spinal cord injury following cervical spine surgery were identified. Institutional incidence rates ranged from 0.0% to 0.24%. Of the 3 patients with quadriplegia, one underwent anterior-only surgery with 2-level cervical corpectomy, one underwent anterior surgery with corpectomy in addition to posterior surgery, and one underwent posterior decompression and fusion surgery alone. One patient had complete neurologic recovery, one partially recovered, and one did not recover motor function. CONCLUSION: Iatrogenic spinal cord injury following cervical spine surgery is a rare and devastating adverse event. No standard protocol exists that can guarantee prevention of this complication, and there is a lack of consensus regarding evaluation and treatment when it does occur. Emergent imaging with magnetic resonance imaging or computed tomography myelography to evaluate for compressive etiology or malpositioned instrumentation and avoidance of hypotension should be performed in cases of intraoperative and postoperative spinal cord injury

Efficient characterisation of large deviations using population dynamics

We consider population dynamics as implemented by the cloning algorithm for analysis of large deviations of time-averaged quantities. Using the simple symmetric exclusion process as a prototypical example, we investigate the convergence of the results with respect to the algorithmic parameters, focussing on the dynamical phase transition between homogeneous and inhomogeneous states, where convergence is relatively difficult to achieve. We discuss how the performance of the algorithm can be optimised, and how it can be efficiently exploited on parallel computing platforms.Comment: 23 pages, final versio

Plasma Microparticle Tissue Factor Activity in Patients With Antiphospholipid Antibodies With and Without Clinical Complications

Antiphospholipid syndrome (APS) is defined by the association of autoantibodies to certain phospholipid-binding proteins with arterial or venous thrombosis (‘AT’ or ‘VT’, respectively), and/or pregnancy-related morbidity (PM). Antiphospholipid antibodies (aPLA) promote activation of several cell types including monocytes, resulting in procoagulant tissue factor (TF) expression that may contribute to the vascular complications. Since TF synthesis by monocytes is frequently accompanied by release of TF-bearing microparticles, we hypothesized that plasma microparticle TF activity (MP-TF) may be elevated in APS patients and contribute to thrombosis and/or PM. Platelet-poor plasma specimens were obtained from 30 patients with definite APS and 72 patients with asymptomatic aPLA from the Antiphospholipid Syndrome Collaborative Registry (APSCORE). MP-TF was measured by an in-house factor Xa generation assay. The two groups were well matched for gender, age, ethnicity, proportions with underlying SLE, and aPLA profiles. MP-TF (median and (IQR)) in asymptomatic aPLA subjects was 0.09 pg/mL (0.05–0.14) compared to 0.13 pg/mL (0.10–0.17) in APS (p<0.001). No differences in MP-TF levels were observed between APS subjects with PM, thrombosis, or PM + thrombosis. Similarly, among subjects with either APS or asymptomatic aPLA, MP-TF did not differ in the presence or absence of underlying SLE. Prospective studies will be required to determine if plasma MP-TF activity is causally related to thrombotic or gestational complications in APS

Enhanced electrostatic force microscopy reveals higher-order DNA looping mediated by the telomeric protein TRF2

Shelterin protein TRF2 modulates telomere structures by promoting dsDNA compaction and T-loop formation. Advancement of our understanding of the mechanism underlying TRF2-mediated DNA compaction requires additional information regarding DNA paths in TRF2-DNA complexes. To uncover the location of DNA inside protein-DNA complexes, we recently developed the Dual-Resonance-frequency-Enhanced Electrostatic force Microscopy (DREEM) imaging technique. DREEM imaging shows that in contrast to chromatin with DNA wrapping around histones, large TRF2-DNA complexes (with volumes larger than TRF2 tetramers) compact DNA inside TRF2 with portions of folded DNA appearing at the edge of these complexes. Supporting coarse-grained molecular dynamics simulations uncover the structural requirement and sequential steps during TRF2-mediated DNA compaction and result in folded DNA structures with protruding DNA loops as seen in DREEM imaging. Revealing DNA paths in TRF2 complexes provides new mechanistic insights into structure-function relationships underlying telomere maintenance pathways

Reliability and predictive validity of a hepatitis-related symptom inventory in HIV-infected individuals referred for Hepatitis C treatment

<p>Abstract</p> <p>Background</p> <p>We aimed to determine the reliability and validity of a hepatitis symptom inventory and to identify predictors of hepatitis C (HCV) treatment initiation in a cohort of HIV-infected patients.</p> <p>Methods</p> <p>Prospective clinic based study that enrolled patients referred for HCV therapy consideration. A hepatitis symptom inventory and the Center for Epidemiologic Studies Depression Scale (CES-D) were administered to HIV/HCV individuals. The symptom inventory was factor analyzed and subscale reliability estimated with Cronbach's alpha. Predictive validity was evaluated using generalized estimating equations (GEE). Predictors of HCV treatment were identified using logistic regression.</p> <p>Results</p> <p>Between April 2008 to July 2010, 126 HIV/HCV co-infected patients were enrolled in the study. Factor analysis using data from 126 patients yielded a three-factor structure explaining 60% of the variance for the inventory. Factor 1 (neuropsychiatric symptoms) had 14 items, factor 2 (somatic symptoms) had eleven items, and factor 3 (sleep symptoms) had two items, explaining 28%, 22% and 11% of the variance, respectively. The three factor subscales demonstrated high intrinsic consistency reliability. GEE modeling of the 32 patients who initiated HCV therapy showed that patients developed worsening neuropsychiatric and somatic symptoms following HCV therapy with stable sleep symptoms. Bivariate analyses identified the following as predictors of HCV therapy initiation: lower HIV log₁₀RNA, lower scores for neuropsychiatric, somatic and sleep symptoms, lower CES-D scores and white ethnicity. In stepwise multiple logistic regression analysis, low neuropsychiatric symptom score was the strongest independent predictor of HCV therapy initiation and HIV log₁₀RNA was inversely associated with a decision to initiate HCV treatment.</p> <p>Conclusions</p> <p>A 41-item hepatitis-related symptom inventory was found to have a clinically meaningful 3-factor structure with excellent internal consistency reliability and predictive validity. In adjusted analysis, low neuropsychiatric symptom scores and controlled HIV infection were independent predictors of HCV treatment initiation. The usefulness of the HCV symptom inventory in monitoring HCV treatment should be evaluated prospectively.</p

Misplaced Cervical Screws Requiring Reoperation.

STUDY DESIGN: A multicenter, retrospective case series. OBJECTIVE: In the past several years, screw fixation of the cervical spine has become commonplace. For the most part, this is a safe, low-risk procedure. While rare, screw backout or misplaced screws can lead to morbidity and increased costs. We report our experiences with this uncommon complication. METHODS: A multicenter, retrospective case series was undertaken at 23 institutions in the United States. Patients were included who underwent cervical spine surgery from January 1, 2005, to December 31, 2011, and had misplacement of screws requiring reoperation. Institutional review board approval was obtained at all participating institutions, and detailed records were sent to a central data center. RESULTS: A total of 12 903 patients met the inclusion criteria and were analyzed. There were 11 instances of screw backout requiring reoperation, for an incidence of 0.085%. There were 7 posterior procedures. Importantly, there were no changes in the health-related quality-of-life metrics due to this complication. There were no new neurologic deficits; a patient most often presented with pain, and misplacement was diagnosed on plain X-ray or computed tomography scan. The most common location for screw backout was C6 (36%). CONCLUSIONS: This study represents the largest series to tabulate the incidence of misplacement of screws following cervical spine surgery, which led to revision procedures. The data suggest this is a rare event, despite the widespread use of cervical fixation. Patients suffering this complication can require revision, but do not usually suffer neurologic sequelae. These patients have increased cost of care. Meticulous technique and thorough knowledge of the relevant anatomy are the best means of preventing this complication