1,127 research outputs found
AFLOW-QHA3P: Robust and automated method to compute thermodynamic properties of solids
Accelerating the calculations of finite-temperature thermodynamic properties is a major challenge for rational materials design. Reliable methods can be quite expensive, limiting their applicability in autonomous high-throughput workflows. Here, the three-phonon quasiharmonic approximation (QHA) method is introduced, requiring only three phonon calculations to obtain a thorough characterization of the material. Leveraging a Taylor expansion of the phonon frequencies around the equilibrium volume, the method efficiently resolves the volumetric thermal expansion coefficient, specific heat at constant pressure, the enthalpy, and bulk modulus. Results from the standard QHA and experiments corroborate the procedure, and additional comparisons are made with the recently developed self-consistent QHA. The three approaches—three-phonon, standard, and self-consistent QHAs—are all included within the open-source ab initio framework aflow, allowing the automated determination of properties with various implementations within the same framework
Distance as a barrier to cancer diagnosis and treatment: Review of the literature
The burden of travel from a patient’s residence to health care providers is an important issue that can influence access to diagnosis and treatment ofcancer.Although several studies have shown that the travel burden can result in delays in diagnosis and treatment of many common cancers, its role appears underestimated in the treatment of patients in clinical practice. Therefore, we performed a review of the published data on the role of travel burden influencing four items: delay of diagnosis, adequate treatment of cancer, outcome, and quality of life of cancer patients. Forty-seven studies published up to December 2014 were initially identified. Twenty studies were excluded because they did not regard specifically the four items of our review.Twenty-seven studies formed the basis of our study and involved 716,153 patients. The associations between travel burden and (a) cancer stage at diagnosis (12 studies), (b) appropriate treatment (8 studies), (c) outcome (4 studies), and (d) quality of life (1 study) are reported. In addition, in two studies,therelationbetween travel burden and compliance with treatment was examined. The results of our review show that increasing travel requirements are associated with more advanced disease at diagnosis, inappropriatetreatment, aworse prognosis, and a worse quality of life. These results suggest that clinical oncologists should remember the specific travel burden problem for cancer patients, who often need health care services every week or every month for many years
The Potential of Mixtures of Pure Fluids in ORC-based Power Units fed by Exhaust Gases in Internal Combustion Engines
Abstract ORC represents an effective challenge in the waste heat recovery from ICEs. In spite of technological aspects, its thermodynamic design still deserves attention. Mixtures of pure fluids show interesting properties able to improve exergetic efficiency of the Rankine cycle, thanks to the positive slope of the phase changing. They can reduce also ODP and GWP, helping the replacement trends of working fluids. The paper optimizes cycle exergetic efficiency considering mixtures of pure fluids. The use of hydrocarbons in mixtures is particularly suitable and when used in limited fractions with other organic fluids they loses the limits related to the flammability.R245fa is a fluid that obtains a large net power increase when used in mixtures with hydrocarbons, compared to pure fluid an optimized R245fa/benzene mixture, for instance, attains an 11% net power increase
Coordination corrected ab initio formation enthalpies
The correct calculation of formation enthalpy is one of the enablers of ab-initio computational materials design. For several classes of systems (e.g. oxides) standard density functional theory produces incorrect values. Here we propose the “coordination corrected enthalpies” method (CCE), based on the number of nearest neighbor cation–anion bonds, and also capable of correcting relative stability of polymorphs. CCE uses calculations employing the Perdew, Burke and Ernzerhof (PBE), local density approximation (LDA) and strongly constrained and appropriately normed (SCAN) exchange correlation functionals, in conjunction with a quasiharmonic Debye model to treat zero-point vibrational and thermal effects. The benchmark, performed on binary and ternary oxides (halides), shows very accurate room temperature results for all functionals, with the smallest mean absolute error of 27(24) meV/atom obtained with SCAN. The zero-point vibrational and thermal contributions to the formation enthalpies are small and with different signs—largely canceling each other
Toward the Quadruple Aim: Impact of a Humanistic Mentoring Program to Reduce Burnout and Foster Resilience.
Objective:To assess the effect of a faculty development program (Mentoring and Professionalism in Training [MAP-IT]) that fosters humanism in medicine on elements of burnout and the development of resilience. Participants and Methods:The cohort of participants was drawn from a cross-section of disciplines and represented a diverse group of health professionals, including physicians, nurses, physician assistants, pharmacists, psychologists, social workers, and chaplains. The 106 participants were divided into 12 groups, each of which was facilitated by two or three leaders. Each group completed the MAP-IT curriculum from October 1, 2017, through July 31, 2018. All participants and leaders completed the Connor-Davidson Resilience Scale and the Maslach Burnout Inventory (assessing emotional exhaustion, depersonalization, and personal accomplishment) before and after completion of the program. Results:The participants\u27 scores for emotional exhaustion and depersonalization remained unchanged following the completion of the MAP-IT curriculum. However, their scores for personal accomplishment and resilience increased significantly and approximated those of the leaders. Conclusion:The MAP-IT program has shown effectiveness both in fostering resilience and a sense of personal accomplishment. The time is ripe for institutional programming to create and foster the personal tools needed to prevent burnout and its sequelae
Intraventricular liponeurocytoma: The role of surgery and adjuvant therapy
Background: After a series of case reports, in the WHO classification of 2007, liponeurocytomas were reclassified as grade II tumors and confirmed in the last WHO classification of 2016. We describe a rare case of intraventricular location of liponeurocytoma with review of the literature and propose the management of these rare lesions. Methods: We reviewed the pertinent english literature and extracted 9 articles to discuss 12 cases of intraventricular liponeurocytoma. We reported demographics and clinical data cases including our case. Results: Patients mean age is 37years. There is a male prevalence. All 12 patients underwent surgical treatment. A total tumor resection was obtained in 66,6%. There is one mortality reported due to intraventricular hemorrhage. In 4 cases K67/MIB-1 resulted 3% after subtotal removal. Keywords: Liponeurocytoma, Fourth ventricle, Ki-67 index, Neurocytom
Low temperature superlattice in monoclinic PZT
TEM has shown that the strongly piezoelectric material Pb(Zr0.52Ti0.48)O3
separates into two phases at low temperatures. The majority phase is the
monoclinic phase previously found by x-ray diffraction. The minority phase,
with a nanoscale coherence length, is a slightly distorted variant of the first
resulting from the anti-phase rotation of the oxygen octahedra about [111].
This work clears up a recent controversy about the origin of superlattice peaks
in these materials, and supports recent theoretical results predicting the
coexistence of ferroelectric and rotational instabilities.Comment: REVTeX4, 4 eps figures embedded. JPG version of figs. 2&4 is also
include
Correlation Between Volcanic and Tectonic Segmentation of Fast-Spreading Ridges: Evidence from Volcanic Structures and Lava Flow Morphology on the East Pacific Rise at 9Ëš-10ËšN
Combined analyses of volcanic features in DSL-120 sonar data and Argo I images along the ridge crest of the East Pacific Rise, 9_090–540N reveal a consistent decrease in inferred lava effusion rate toward the ends of third-order segments. The correlation of tectonic segmentation and volcanic style suggests that third-order segmentation corresponds to the volcanic segmentation of the ridge. Along-axis changes in volcanic structures (from collapse troughs to basaltic lava domes) and lava morphology (from sheet to pillow flows) coincide with the boundaries of morphologically defined third order tectonic segments of the ridge crest visible in shipboard multibeam bathymetry. Pillow lava flows cover 25% of the surveyed area of the ridge crest and are closely associated with small lava domes that occur primarily at third-order segment ends. An additional 25% of the surveyed area of the ridge crest is covered by sheet lava flows found in close association with an axial collapse trough. The remaining terrain consists of lobate lava flows. We interpret the spatial correlations of morphologic, structural, seismic, and petrologic data as evidence that individual volcanic plumbing systems are organized at _20 km spacing along the ridge axis (third-order segment scale) in agreement with the hypothesis that volcanic and tectonic segmentations are correlated. For fast spreading ridges, we estimate that the longevity of volcanic segments is _104–105 years, 1–3 orders of magnitude longer than fourth-order segments (_102–103 years). This implies the present pattern of hydrothermal activity may reorganize tens or hundreds of times while volcanic segmentation remains fairly stable
Animal models of hepatocellular carcinoma prevention
Hepatocellular carcinoma (HCC) is a deadly disease and therapeutic efficacy in advanced HCC is limited. Since progression of chronic liver disease to HCC involves a long latency period of a few decades, a significant window of therapeutic opportunities exists for prevention of HCC and improve patient prognosis. Nonetheless, there has been no clinical advancement in instituting HCC chemopreventive strategies. Some of the major challenges are heterogenous genetic aberrations of HCC, significant modulation of tumor microenvironment and incomplete understanding of HCC tumorigenesis. To this end, animal models of HCC are valuable tools to evaluate biology of tumor initiation and progression with specific insight into molecular and genetic mechanisms involved. In this review, we describe various animal models of HCC that facilitate effective ways to study therapeutic prevention strategies that have translational potential to be evaluated in a clinical context © 2019 by the authors. Licensee MDPI, Basel, Switzerland
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