GpABC: a Julia package for approximate Bayesian computation with Gaussian process emulation

Motivation Approximate Bayesian computation (ABC) is an important framework within which to infer the structure and parameters of a systems biology model. It is especially suitable for biological systems with stochastic and nonlinear dynamics, for which the likelihood functions are intractable. However, the associated computational cost often limits ABC to models that are relatively quick to simulate in practice. Results We here present a Julia package, GpABC, that implements parameter inference and model selection for deterministic or stochastic models using i) standard rejection ABC or ABC-SMC, or ii) ABC with Gaussian process emulation. The latter significantly reduces the computational cost. Availability and Implementation https://github.com/tanhevg/GpABC.jl Supplementary information Supplementary data are available at Bioinformatics online

Spin-orbiton and quantum criticality in FeSc2S4

In FeSc2S4 spin-orbital exchange competes with strong spin-orbit coupling, suppressing long-range spin and orbital order and, hence, this material represents one of the rare examples of a spin-orbital liquid ground state. Moreover, it is close to a quantum-critical point separating the ordered and disordered regimes. Using THz and FIR spectroscopy we study low-lying excitations in FeSc2S4 and provide clear evidence for a spin-orbiton, an excitation of strongly entangled spins and orbitals. It becomes particularly well pronounced upon cooling, when advancing deep into the quantum-critical regime. Moreover, indications of an underlying structureless excitation continuum are found, a possible signature of quantum criticality.Comment: 11 pages, 11 figures (including 4 pages and 5 figures in Supplemental Material). Revised version according to suggestions of referees. Phys. Rev. B (in press

Exploring undergraduate students’ usage pattern of mobile apps for education

In recent years, with the general adoption of smartphones with computing power comparable to desktop computers, mobile applications (apps) have experienced a surge in popularity. However, there are few studies conducted about their educational use, especially in Southeast Asia. To close this research gap, this study aims to provide a current overview of mobile apps usage in higher education. Besides exploring the actual use of apps, the technology acceptance model was applied to examine (1) undergraduate students’ perceptions, which involve perceived usefulness and perceived ease of use, towards adopting mobile apps for educational purposes, and (2) their overall attitude toward such adoption. Both quantitative and qualitative methods were used to collect data from 150 undergraduate students in Business, Education, and Engineering in Hong Kong. The results show undergraduate students use mobile apps frequently to engage in learning activities related to their academic studies, with a particularly focus on communication and collaborative working, accessing academic resources, and checking a dictionary. However, the discrepancies in using apps for academic purposes are not significant between the three faculties. Meanwhile, perceived usefulness has a more positive impact on overall attitude compared with the impact of perceived ease of use. The investigation will help tertiary institutions, library service providers, and educators develop and assess strategic planning for education collaborating with mobile apps. This paper could also give app developers some suggestions for app design based on actual usage and students’ information needs.preprin

Is there an association between vitamin D and risk of stroke?: a North Indian study

Background: Vitamin D deficiency is present in India in epidemic proportions despite plenty of sunshine. Reduced plasma 25(OH) D concentrations as a diagnostic marker of vitamin D deficiency have been in past decade associated with several well-established risk factors for ischaemic stroke, such as arterial hypertension, thrombosis, atherosclerosis. The aims and objectives of this study was to compare the serum 25(OH) D levels between the first ever acute stroke patients and healthy controls.Methods: A cross-sectional, case control study was conducted in a tertiary care hospital in New Delhi situated in north India. Serum 25‑hydroxyvitamin D (25(OH) D) levels in 85 patients of ischemic stroke, presenting within 7 days of onset of stroke was measured and was compared with 70 age and gender matched controls.Results: The mean age was 61.02±11.58 years and 58.63±11.28 years in cases and controls respectively. Females constituted 37.6% of the total number of cases and 43.4% of the controls. The age and gender-distribution were comparable between the cases and controls. The median value (IQR) of serum 25(OH) vitamin D level was 7.94 ng/mL (4.59-14.00) in the cases and it was 8.82 ng/mL (5.59-14.70) in the controls. The difference between the serum 25(OH) vitamin D levels of the two groups was not found to be statistically significant.Conclusions: There is a high prevalence of biochemical hypo-vitaminosis D in apparently healthy Indians of all age and sex groups despite adequate sunshine. There is no association between low vitamin D levels and stroke

Interplay of fission modes in mass distribution of light actinide nuclei 225,227Pa

Fission-fragment mass distributions were measured for 225,227Pa nuclei formed in fusion reactions of 19F + 206, 208Pb around fusion barrier energies. Mass-angle correlations do not indicate any quasi-fission like events in this bombarding energy range. Mass distributions were fitted by Gaussian distribution and mass variance extracted. At below-barrier energies, the mass variance was found to increase with decrease in energy for both nuclei. Results from present work were compared with existing data for induced fission of 224, 226Th and 228U around barrier energies. Enhancement in mass variance of 225, 227Pa nuclei at below-barrier energies shows evidence for presence of asymmetric fission events mixed with symmetric fission events. This is in agreement with the results of mass distributions of nearby nuclei 224, 226Th and 228U where two-mode fission process was observed. Two-mode feature of fission arises due to the shell effects changing the landscape of the potential energy surfaces at low excitation energies. The excitation-energy dependence of the mass variance gives strong evidence for survival of microscopic shell effects in fission of light actinide nuclei 225, 227Pa with initial excitation energy ~30 - 50 MeV