327 research outputs found
Small-Scale Interstellar Na I Structure Toward M92
We have used integral field echelle spectroscopy with the DensePak
fiber-optic array on the KPNO WIYN telescope to observe the central 27" x 43"
of the globular cluster M92 in the Na I D wavelength region at a spatial
resolution of 4". Two interstellar Na I absorption components are evident in
the spectra at LSR velocities of 0 km/s (Cloud 1) and -19 km/s (Cloud 2).
Substantial strength variations in both components are apparent down to scales
limited by the fiber-to-fiber separations. The derived Na I column densities
differ by a factor of 4 across the Cloud 1 absorption map and by a factor of 7
across the Cloud 2 map. Using distance upper limits of 400 and 800 pc for Cloud
1 and Cloud 2, respectively, the absorption maps indicate structure in the ISM
down to scales of 1600 and 3200 AU. The fiber-to-fiber Na I column density
differences toward M92 are comparable to those found in a similar study of the
ISM toward the globular cluster M15. Overall, the structures in the
interstellar components toward M92 have significantly lower column densities
than those toward M15. We interpret these low column density structures as
small-scale turbulent variations in the gas and compare them to the
larger-scale, higher column density variations toward M15, which may be the
hallmarks of actual H I structures.Comment: 9 pages, 2 figures, accepted for publication in ApJ Letter
On the Invariant Theory of Weingarten Surfaces in Euclidean Space
We prove that any strongly regular Weingarten surface in Euclidean space
carries locally geometric principal parameters. The basic theorem states that
any strongly regular Weingarten surface is determined up to a motion by its
structural functions and the normal curvature function satisfying a geometric
differential equation. We apply these results to the special Weingarten
surfaces: minimal surfaces, surfaces of constant mean curvature and surfaces of
constant Gauss curvature.Comment: 16 page
Renewable Power Options for Electrical Generation on Kaua'i: Economics and Performance Modeling
The Hawaii Clean Energy Initiative (HCEI) is working with a team led by the U.S. Department of Energy's (DOE) National Renewable Energy Laboratory (NREL) to assess the economic and technical feasibility of increasing the contribution of renewable energy in Hawaii. This part of the HCEI project focuses on working with Kaua'i Island Utility Cooperative (KIUC) to understand how to integrate higher levels of renewable energy into the electric power system of the island of Kaua'i. NREL partnered with KIUC to perform an economic and technical analysis and discussed how to model PV inverters in the electrical grid
Integrating High Levels of Renewables in to the Lanai Electric Grid
The Hawaii Clean Energy Initiative (HCEI) is working with a team led by the U.S. Department of Energy's (DOE) National Renewable Energy Laboratory (NREL) and Sandia National Laboratory (Sandia) to assess the economic and technical feasibility of increasing the contribution of renewable energy sources on the island of Lanai with a stated goal of reaching 100% renewable energy. NREL and Sandia partnered with Castle & Cooke, Maui Electric Company (MECO), and SRA International to perform the assessment
Recommended from our members
Serious gaming and gamification education in health professions: Systematic review
Background:
There is a worldwide shortage of health workers, and this issue requires innovative education solutions. Serious gaming and gamification education have the potential to provide a quality, cost-effective, novel approach that is flexible, portable, and enjoyable and allow interaction with tutors and peers.
Objective:
The aim of this systematic review was to evaluate the effectiveness of serious gaming/gamification for health professions education compared with traditional learning, other types of digital education, or other serious gaming/gamification interventions in terms of patient outcomes, knowledge, skills, professional attitudes, and satisfaction (primary outcomes) as well as economic outcomes of education and adverse events (secondary outcomes).
Methods:
A comprehensive search of MEDLINE, EMBASE, Web of Knowledge, Educational Resources Information Centre, Cochrane Central Register of Controlled Trials, PsycINFO, and Cumulative Index to Nursing and Allied Health Literature was conducted from 1990 to August 2017. Randomized controlled trials (RCTs) and cluster RCTs were eligible for inclusion. Two reviewers independently searched, screened, and assessed the study quality and extracted data. A meta-analysis was not deemed appropriate due to the heterogeneity of populations, interventions, comparisons, and outcomes. Therefore, a narrative synthesis is presented.
Results:
A total of 27 RCTs and 3 cluster RCTs with 3634 participants were included. Two studies evaluated gamification interventions, and the remaining evaluated serious gaming interventions. One study reported a small statistically significant difference between serious gaming and digital education of primary care physicians in the time to control blood pressure in a subgroup of their patients already taking antihypertensive medications. There was evidence of a moderate-to-large magnitude of effect from five studies evaluating individually delivered interventions for objectively measured knowledge compared with traditional learning. There was also evidence of a small-to-large magnitude of effect from 10 studies for improved skills compared with traditional learning. Two and four studies suggested equivalence between interventions and controls for knowledge and skills, respectively. Evidence suggested that serious gaming was at least as effective as other digital education modalities for these outcomes. There was insufficient evidence to conclude whether one type of serious gaming/gamification intervention is more effective than any other. There was limited evidence for the effects of serious gaming/gamification on professional attitudes. Serious gaming/gamification may improve satisfaction, but the evidence was limited. Evidence was of low or very low quality for all outcomes. Quality of evidence was downgraded due to the imprecision, inconsistency, and limitations of the study.
Conclusions:
Serious gaming/gamification appears to be at least as effective as controls, and in many studies, more effective for improving knowledge, skills, and satisfaction. However, the available evidence is mostly of low quality and calls for further rigorous, theory-driven research
Recommended from our members
Integrating Renewable Energy into the Transmission and Distribution System of the U. S. Virgin Islands
This report focuses on the economic and technical feasibility of integrating renewable energy technologies into the U.S. Virgin Islands transmission and distribution systems. The report includes three main areas of analysis: 1) the economics of deploying utility-scale renewable energy technologies on St. Thomas/St. John and St. Croix; 2) potential sites for installing roof- and ground-mount PV systems and wind turbines and the impact renewable generation will have on the electrical subtransmission and distribution infrastructure, and 3) the feasibility of a 100- to 200-megawatt power interconnection of the Puerto Rico Electric Power Authority (PREPA), Virgin Islands Water and Power Authority (WAPA), and British Virgin Islands (BVI) grids via a submarine cable system
A Physics-based Investigation of Pt-salt Doped Carbon Nanotubes for Local Interconnects
We investigate, by combining physical and electrical measurements together with an atomistic-to-circuit modeling approach, the conductance of doped carbon nanotubes (CNTs) and their eligibility as possible candidate for next generation back-end-of-line (BEOL) interconnects. Ab-initio simulations predict a doping-related shift of the Fermi level, which reduces shell chirality variability and improves electrical conductance up to 90% by converting semiconducting shells to metallic. Circuit-level simulations predict up to 88% signal delay improvement with doped vs. pristine CNT. Electrical measurements of Pt-salt doped CNTs provide up to 50% of resistance reduction which is a milestone result for future CNT interconnect technology
Smc5/6 coordinates formation and resolution of joint molecules with chromosome morphology to ensure meiotic divisions
During meiosis, Structural Maintenance of Chromosome (SMC) complexes underpin two fundamental features of meiosis: homologous recombination and chromosome segregation. While meiotic functions of the cohesin and condensin complexes have been delineated, the role of the third SMC complex, Smc5/6, remains enigmatic. Here we identify specific, essential meiotic functions for the Smc5/6 complex in homologous recombination and the regulation of cohesin. We show that Smc5/6 is enriched at centromeres and cohesin-association sites where it regulates sister-chromatid cohesion and the timely removal of cohesin from chromosomal arms, respectively. Smc5/6 also localizes to recombination hotspots, where it promotes normal formation and resolution of a subset of joint-molecule intermediates. In this regard, Smc5/6 functions independently of the major crossover pathway defined by the MutLγ complex. Furthermore, we show that Smc5/6 is required for stable chromosomal localization of the XPF-family endonuclease, Mus81-Mms4Eme1. Our data suggest that the Smc5/6 complex is required for specific recombination and chromosomal processes throughout meiosis and that in its absence, attempts at cell division with unresolved joint molecules and residual cohesin lead to severe recombination-induced meiotic catastroph
HI spectra and column densities toward HVC and IVC probes
We show 21-cm line profiles in the direction of stars and extragalactic
objects, lying projected on high- and intermediate-velocity clouds (HVCs and
IVCs). About half of these are from new data obtained with the Effelsberg 100-m
telescope, about a quarter are extracted from the Leiden-Dwingeloo Survey (LDS)
and the remaining quarter were observed with other single-dish telescopes. HI
column densities were determined for each HVC/IVC. Wakker (2001) (Paper I) uses
these in combination with optical and ultraviolet high-resolution measurements
to derive abundances. Here, an analysis is given of the difference and ratio of
N(HI) as observed with a 9 arcmin versus a 35 arcmin beam. For HVCs and IVCs
the ratio N(HI-9 arcmin)/N(HI-35 arcmin) lies in the range 0.2-2.5. For
low-velocity gas this ratio ranges from 0.75 to 1.3 (the observed ratio is
0.85-1.4, but it appears that the correction for stray radiation is slightly
off). The smaller range for the low-velocity gas may be caused by confusion in
the line of sight, so that a low ratio in one component can be compensated by a
high ratio in another -- for 11 low-velocity clouds fit by one component the
distribution of ratios has a larger dispersion. Comparison with higher angular
resolution data is possible for sixteen sightlines. Eight sightlines with HI
data at 1 arcmin-2 arcmin resolution show a range of 0.75-1.25 for N(HI-2
arcmin)/N(HI-9 arcmin), while in eight other sightlines N(HI-Ly-alpha)/N(HI-9
arcmin) ranges from 0.74 to 0.98.Comment: To appear in the "Astrophysical Journal Supplement"; 45 pages;
degraded figures (astro-ph restriction) - ask for good version
- …