813 research outputs found

    Are Student Loan Default Rates Linked to Institutional Capacity?

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    As more undergraduates have taken out loans to attend college, the number of borrowers who fail to repay their student loans has increased. While previous research has focused on students’ likelihood to default, this study employed institutional cohort default rates (CDRs) as an outcome variable. Using Integrated Postsecondary Education Data System, this study investigated the association between institutional effectiveness and CDRs. Coupled with multilevel modeling, the study also observed the effects of state-level factors, such as state appropriation and unemployment, on CDRs. The results showed that institutional characteristics—e.g., proportion of minority students, admission test scores, retention rates, and instructional expenses—are strongly associated with institutional CDRs. This suggests that institutional default rates are mainly a function of the students that institutions enroll, and future studies should include institutional as well as student factors to provide policy makers and researchers with a more comprehensive understanding of institutional CDRs

    Collusions Between Patients and Clinicians in End-of-Life Care: Why Clarity Matters.

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    Collusion, an unconscious dynamic between patients and clinicians, may provoke strong emotions, unreflected behaviors, and a negative impact on care. Collusions, prevalent in the health care setting, are triggered by situations which signify an unresolved psychological issue relevant for both, patient and clinician. After an introductory definition of collusion, two archetypal situations of collusion-based on material from a regular supervision of a palliative care specialist by a liaison psychiatrist-and means of working through collusion are presented. The theoretical framework of collusion is then described and the conceptual shortcomings of the palliative care literature in this respect discussed, justifying the call for more clarity. Finally, cultural aspects and societal injunctions on the dying, contributing to the development of collusion in end-of-life care, are discussed

    Theoretical and Numerical Analysis of an Optimal Execution Problem with Uncertain Market Impact

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    This paper is a continuation of Ishitani and Kato (2015), in which we derived a continuous-time value function corresponding to an optimal execution problem with uncertain market impact as the limit of a discrete-time value function. Here, we investigate some properties of the derived value function. In particular, we show that the function is continuous and has the semigroup property, which is strongly related to the Hamilton-Jacobi-Bellman quasi-variational inequality. Moreover, we show that noise in market impact causes risk-neutral assessment to underestimate the impact cost. We also study typical examples under a log-linear/quadratic market impact function with Gamma-distributed noise.Comment: 24 pages, 14 figures. Continuation of the paper arXiv:1301.648

    A Single-Institution Review of Portosystemic Shunts in Children: An Ongoing Discussion

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    Purpose. Review the safety and long-term success with portosystemic shunts in children at a single institution. Methods. An IRB-approved, retrospective chart review of all children ages 19 and undergoing surgical portosystemic shunt from January 1990–September 2008. Results. Ten patients were identified, 8 females and 2 males, with a mean age of 15 years (range 5–19 years). Primary diagnoses were congenital hepatic fibrosis (5), hepatic vein thrombosis (2), portal vein thrombosis (2), and cystic fibrosis (1). Primary indications were repeated variceal bleeding (6), symptomatic hypersplenism (2), and significant liver dysfunction (2). Procedures performed were distal splenorenal bypass (4), side-to-side portocaval shunt (3), proximal splenorenal shunt (2), and an interposition H-graft portocaval shunt (1). There was no perioperative mortality and only minor morbidity. Seventy percent of patients had improvement of their symptoms. Eighty percent of shunts remained patent. Two were occluded at a median follow-up of 50 months (range 0.5–13.16 years). Two patients underwent subsequent liver transplantation. Two patients died at 0.5 and 12.8 years postoperatively, one from multisystem failure with cystic fibrosis and one from post-operative transplant complications. Conclusions. The need for portosystemic shunts in children is rare. However, in the era of liver transplantation, portosystemic shunts in selected patients with well-preserved liver function remains important. We conclude that portosystemic shunts are safe and efficacious in the control of variceal hemorrhage and symptoms related to hypersplenism

    Photochemical Processes in a Rhenium(I) Tricarbonyl N-Heterocyclic Carbene Complex Studied by Time-Resolved Measurements

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    We carried out time-resolved infrared (TR-IR) and emission lifetime measurements on a Re(I) carbonyl complex having an N-heterocyclic carbene ligand, namely, fac-[Re(CO)3(PyImPh)Br], under photochemically reactive (in solution in acetonitrile) and nonreactive (in solution in dichloromethane) conditions to investigate the mechanism of photochemical ligand substitution reactions. The TR-IR measurements revealed that no reaction occurs on a picosecond time scale and the cationic product, namely, fac-[Re(CO)3(PyImPh)(MeCN)](+), is produced on a nanosecond time scale only in solution in acetonitrile, which indicates that the reaction proceeds thermally from the excited state. Because no other products were observed by TR-IR, we concluded that this cationic product is an intermediate species for further reactions. The measurements of the temperature-dependent emission lifetime and analysis using transition-state theory revealed that the photochemical substitution reaction proceeds from a metal-to-ligand charge transfer excited state, the structure of which allows the potential coordination of a solvent molecule. Thus, the coordinating capacity of the solvent determines whether the reaction proceeds or not. This mechanism is different from those of photochemical reactions of other types of Re(I) carbonyl complexes owing to the unique characteristics of the carbene ligand

    Cryo-EM structure of the volume-regulated anion channel LRRC8D isoform identifies features important for substrate permeation

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    Members of the leucine-rich repeat-containing 8 (LRRC8) protein family, composed of the five LRRC8A-E isoforms, are pore-forming components of the volume-regulated anion channel (VRAC). LRRC8A and at least one of the other LRRC8 isoforms assemble into heteromers to generate VRAC transport activities. Despite the availability of the LRRC8A structures, the structural basis of how LRRC8 isoforms other than LRRC8A contribute to the functional diversity of VRAC has remained elusive. Here, we present the structure of the human LRRC8D isoform, which enables the permeation of organic substrates through VRAC. The LRRC8D homo-hexamer structure displays a two-fold symmetric arrangement, and together with a structure-based electrophysiological analysis, revealed two key features. The pore constriction on the extracellular side is wider than that in the LRRC8A structures, which may explain the increased permeability of organic substrates. Furthermore, an N-terminal helix protrudes into the pore from the intracellular side and may be critical for gating

    Bowing of the band gap pressure coefficients in InGaN alloys

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    The hydrostatic pressure dependence of photoluminescence, dEPL/dp, of InxGa1−xN epilayers has been measured in the full composition range 0_x_1. Furthermore, ab initio calculations of the band gap pressure coefficient dEG/dp were performed. Both the experimental dEPL/dp values and calculated dEG/dp results show pronounced bowing and we find that the pressure coefficients have a nearly constant value of about 25 meV/GPa for epilayers with x_0.4 and a relatively steep dependence for x_0.4. On the basis of the agreement of the observed PL pressure coefficient with our calculations, we confirm that band-to-band recombination processes are responsible for PL emission and that no localized states are involved. Moreover, the good agreement between the experimentally determined dEPL/dp and the theoretical curve of dEG/dp indicates that the hydrostatic pressure dependence of PL measurements can be used to quantify changes of the band gap of the InGaN ternary alloy under pressure, demonstrating that the disorder-related Stokes shift in InGaN does not induce a significant difference between dEPL/dp and dEG/dp. This information is highly relevant for the correct analysis of pressure measurement

    Nitrogen Management in Grasslands and Forage-Based Production Systems–Role of Biological Nitrification Inhibition (BNI)

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    Nitrogen (N), being the most critical and essential nutrient for plant growth, largely determines the productivity in both extensive- and intensive- grassland systems. Nitrification and denitrification processes in the soil are the primary drivers generating reactive-N: NO3-, N2O, and NO, and is largely responsible for N-loss and degradation of grasslands. Suppressing nitrification can thus facilitate the retention of soil-N to sustain long-term productivity of grasslands and forage-based production systems. Certain plants can suppress soil nitrification by releasing inhibitors from roots, a phenomenon termed ‘biological nitrification inhibition’ (BNI). Recent methodological developments (e.g. bioluminescence assay to detect BNIs from plant-root systems) led to significant advances in our ability to quantify and characterize BNI function in pasture grasses. Among grass-pastures, BNI-capacity is strongest in low-N adapted grasses such as Brachiaria humidicola and weakest in high-N environment grasses such as Italian ryegrass (Lolium perenne) and B. brizantha. The chemical identity of some of the BNIs produced in plant tissues and released from roots has now been established and their mode of inhibitory action determined on nitrifying bacteria Nitrosomonas. Synthesis and release of BNIs is a highly regulated and localized process, triggered by the presence of NH4+ in the rhizosphere, which facilitates the release of BNIs close to soil-nitrifier sites. Substantial genotypic variation is found for BNI-capacity in B. humidicola, which opens the way for its geneticmanipulation. Field studies suggest that Brachiaria grasses suppress nitrification and N2O emissions from soil. The potential for exploiting BNI function (from a genetic improvement and a system perspective) to develop production systems that are low-nitrifying, low N2O-emitting, economically efficient and ecologically sustainable, will be the subject of discussion
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