Star Formation Density and Halpha Luminosity Function of an Emission Line Selected Galaxy Sample at z ~ 0.24

We use narrowband imaging (FWHM = 70 A) to select a sample of emission line galaxies between 0.20 <~ z <~ 1.22 in two fields covering 0.5 sq. deg. We use spectroscopic follow-up to select a sub-sample of Halpha emitting galaxies at z ~ 0.24 and determine the Halpha luminosity function and star formation density at z ~ 0.24 for both of our fields. Corrections are made for imaging and spectroscopic incompleteness, extinction and interloper contamination on the basis of the spectroscopic data. When compared to each other, we find the field samples differ by \Delta \alpha = 0.2 in faint end slope and \Delta \log [ L* (ergs/s) ] = 0.2 in luminosity. In the context of other recent surveys, our sample has comparable faint end slope, but a fainter L* turn-over. We conclude that systematic uncertainties and differences in selection criteria remain the dominant sources of uncertainty between Halpha luminosity functions at this redshift. We also investigate average star formation rates as a function of local environment and find typical values consistent with the field densities that we probe, in agreement with previous results. However, we find tentative evidence for an increase in star formation rate with respect to the local density of star forming galaxies, consistent with the scenario that galaxy-galaxy interactions are triggers for bursts of star formation.Comment: Accepted for publication in MNRAS. The paper contains 14 figures and 7 table

Remote sensing of geobotanical relations in Georgia

The application of remote sensing to geological investigations, with special attention to geobotanical factors, was evaluated. The general areas of investigation included: (1) recognition of mineral deposits; (2) geological mapping; (3) delineation of geological structure, including areas of complex tectonics; and (4) limestone areas where ground withdrawal had intensified surface collapse

FARMERS' DECISION PROCESSES AND ADOPTION OF CONSERVATION TILLAGE

In a transect survey of crop residue levels in 1995 and 1996, two Minnesota counties had very different percentages of cropland with desired residue cover even though the soil types were similar. To gain a better understanding of the reasons behind this difference, the farmers in these two counties were surveyed about their use or lack of use of conservation tillage practices. A statistical logit analysis of survey responses showed farmers are more apt to adopt conservation tillage if they are larger; are more concerned about erosion on their land; have made a recent major investment in the farm; use other producers for tillage information; have the management skill for conservation tillage; and believe conservation tillage will fit with their production goals and the physical setting of their farm. Two counterintuitive findings are the negative effects of the ease of finding information and the degree of control of the adoption decision. The costs and labor requirements of conservation tillage were important but not as statistically significant as those factors just listed. Some variables, that are often listed as potentially important factors, were not found to be important in this survey. These included the long-term viability of the farm; the age, education, and experience of the farmer; the debt level of the farm; whether a family member wanted to continue farming; the proportion of land rented; the use of other sources for tillage information; the complexity of conservation tillage practices; the producer's planning horizon; the risk of negative returns; the availability of support for conservation tillage systems; and the quality of conservation tillage information.Crop Production/Industries,

The multidimensionality of health protective behaviors

This study explored the relationship among health protective behaviors in an asymptomatic population and identified multiple dimensions. A battery containing measures of health locus of control, general well-being and health value was given to 395 college students. The findings suggested that the three sets of variables offered predictive models unique to each health behavior dimension. Perceived outcomes or benefits were also assessed in relation to the specific health behaviors endorsed by each individual and were found to differentially relate to the various dimensions, providing suggestive evidence for underlying motivations. Several implications were discussed. First, multiple models are needed given multiple dimensions of health behavior. Second, health behaviors are not always performed for health related reasons, and alternative motivations need to be considered. Once identified, these motivations will allow better refinement of health enhancement models based on an approach theory, rather than one of disease-avoiDance

Effects of Synaptic and Myelin Plasticity on Learning in a Network of Kuramoto Phase Oscillators

Models of learning typically focus on synaptic plasticity. However, learning is the result of both synaptic and myelin plasticity. Specifically, synaptic changes often co-occur and interact with myelin changes, leading to complex dynamic interactions between these processes. Here, we investigate the implications of these interactions for the coupling behavior of a system of Kuramoto oscillators. To that end, we construct a fully connected, one-dimensional ring network of phase oscillators whose coupling strength (reflecting synaptic strength) as well as conduction velocity (reflecting myelination) are each regulated by a Hebbian learning rule. We evaluate the behavior of the system in terms of structural (pairwise connection strength and conduction velocity) and functional connectivity (local and global synchronization behavior). We find that for conditions in which a system limited to synaptic plasticity develops two distinct clusters both structurally and functionally, additional adaptive myelination allows for functional communication across these structural clusters. Hence, dynamic conduction velocity permits the functional integration of structurally segregated clusters. Our results confirm that network states following learning may be different when myelin plasticity is considered in addition to synaptic plasticity, pointing towards the relevance of integrating both factors in computational models of learning.Comment: 39 pages, 15 figures This work is submitted in Chaos: An Interdisciplinary Journal of Nonlinear Scienc

If you say so:A mixed-method study of hospital mergers and quality of care

Background: Despite a lack of supporting evidence, hospitals continue to merge in pursuit of quality improvements. Purpose: We seek to develop a more thorough understanding of the quality effects of hospital mergers by integrating various theoretical perspectives using a mixed-methods design. Methodology: Quantitatively, we tested the quality effect of all consummated hospital mergers in the Netherlands between 2008 and 2014 on 15 quality indicators (with 82 measurements at hospital, department, and disease levels) using a difference-in-difference approach with Bonferroni correction. Qualitatively, we conducted three comparative case studies to examine how hospital executives, managers, and medical professionals perceive the quality impact of hospital mergers. Results: Our quantitative results reveal few significant effects of hospital mergers on quality of care at all levels. After applying Bonferroni correction, two quality indicators are negatively associated with hospital mergers. However, the qualitative results indicate that hospital staff have positive perceptions of the mergers’ quality implications, resulting from scale and shock effects. Conclusion: The perceptions of hospital staff regarding mergers diametrically oppose their measurable effects. However, the operationalization of quality by hospital staff members differs considerably from the way it is quantitatively measured. The positive perceptions of hospital staff toward mergers could further contribute to the institutionalization of mergers as a quality improvement strategy. Practice Implications: Hospital managers seeking measurable quality improvements should be wary of merging, despite potential positive perceptions toward it within the organization. In case they do decide to merge, mitigating difficulties in the postmerger integration processes seem most pertinent to achieve measurable effects

Interactions between directly and parametrically driven vibration modes in a micromechanical resonator

The interactions between parametrically and directly driven vibration modes of a clamped-clamped beam resonator are studied. An integrated piezoelectric transducer is used for direct and parametric excitation. First, the parametric amplification and oscillation of a single mode are analyzed by the power and phase dependence below and above the threshold for parametric oscillation. Then, the motion of a parametrically driven mode is detected by the induced change in resonance frequency in another mode of the same resonator. The resonance frequency shift is the result of the nonlinear coupling between the modes by the displacement-induced tension in the beam. These nonlinear modal interactions result in the quadratic relation between the resonance frequency of one mode and the amplitude of another mode. The amplitude of a parametrically oscillating mode depends on the square root of the pump frequency. Combining these dependencies yields a linear relation between the resonance frequency of the directly driven mode and the frequency of the parametrically oscillating mode.Comment: 5 pages, 4 figure

CRISPR-Cas antimicrobials: Challenges and future prospects

This is the final version. Available from PLoS via the DOI in this record.Antimicrobial resistance (AMR) poses a serious threat to modern medicine and may render common infections untreatable. The discovery of new antibiotics has come to a relative standstill during the last decade [1], and developing novel approaches to tackle the spread of AMR genes will require significant efforts in the coming years [2]. In 2014, several groups independently demonstrated how CRISPR-Cas (clustered regularly interspaced short palindromic repeats-CRISPR–associated), a bacterial immune system now widely used for genome editing, can selectively remove AMR genes from bacterial populations. Here, we discuss the current state of the field of CRISPR-Cas antimicrobials, the challenges ahead, and how they may be overcome.Biotechnology & Biological Sciences Research Council (BBSRC)Medical Research CouncilNatural Environment Research CouncilWellcome TrustEuropean Research CouncilPeople Programme (Marie Curie Actions) of the European Union’s Horizon 202

The properties of the brightest Lyα emitters at z ∼ 5.7

We use deep Very Large Telescope (VLT) optical and near-infrared spectroscopy and deep Spitzer/IRAC imaging to examine the properties of two of the most luminous Lyα emitters at z= 5.7. The continuum redward of the Lyα line is clearly detected in both objects, thus facilitating a relatively accurate measurement (10-20 per cent uncertainties) of the observed rest-frame equivalent widths, which are around 160 Å for both objects. Through detailed modelling of the profile of the Lyα line with a 3D Monte Carlo radiative transfer code, we estimate the intrinsic rest-frame equivalent width of Lyα and find values that are around 300 Å, which is at the upper end of the range allowed for very young, moderately metal-poor star-forming galaxies. However, the uncertainties are large and values as high as 700 Å are permitted by the data. Both Lyα emitters are detected at 3.6 m in deep images taken with the Spitzer Space Telescope. We use these measurements, the measurement of the continuum redward of Lyα and other photometry to constrain the spectral energy distributions of these very luminous Lyα emitters and to compare them with three similar Lyα emitters from the literature. The contribution from nebular emission is included in our models: excluding it results in significantly higher masses. Four of the five Lyα emitters have masses of the order of ∼109 M⊙ and fairly high specific star formation rates (≳10-100 Gyr−1). While our two Lyα emitters appear similar in terms of the observed Lyα rest-frame equivalent width, they are quite distinct from each other in terms of age, mass and star formation history. Evidence for dust is found in all objects, and emission from nebular lines often makes a dominant contribution to the rest-frame 3.6 m flux. Rich in emission lines, these objects are prime targets for the next generation of extremely large telescopes, the James Webb Space Telescope (JWST) and the Atacama Large Millimeter Array (ALMA