A Deep Search For Faint Galaxies Associated With Very Low-redshift C IV Absorbers: III. The Mass- and Environment-dependent Circumgalactic Medium

Using Hubble Space Telescope Cosmic Origins Spectrograph observations of 89 QSO sightlines through the Sloan Digital Sky Survey footprint, we study the relationships between C IV absorption systems and the properties of nearby galaxies as well as large-scale environment. To maintain sensitivity to very faint galaxies, we restrict our sample to 0.0015 < z < 0.015, which defines a complete galaxy survey to L > 0.01 L* or stellar mass log M_* > 8 Msun. We report two principal findings. First, for galaxies with impact parameter rho < 1 rvir, C IV detection strongly depends on the luminosity/stellar mass of the nearby galaxy. C IV is preferentially associated with galaxies with log M_* > 9.5 Msun; lower mass galaxies rarely exhibit significant C IV absorption (covering fraction f = 9 +12-6% for 11 galaxies with log M_* < 9.5 Msun). Second, C IV detection within the log M_* > 9.5 Msun population depends on environment. Using a fixed-aperture environmental density metric for galaxies with rho < 160 kpc at z < 0.055, we find that 57+/-12% (8/14) of galaxies in low-density regions (regions with fewer than seven L > 0.15 L* galaxies within 1.5 Mpc) have affiliated C IV absorption; however, none (0/7) of the galaxies in denser regions show C IV. Similarly, the C IV detection rate is lower for galaxies residing in groups with dark-matter halo masses of log Mhalo > 12.5 Msun. In contrast to C IV, H I is pervasive in the CGM without regard to mass or environment. These results indicate that C IV absorbers with log N(C IV) > 13.5 cm^-2 trace the halos of log M_* > 9.5 Msun galaxies but also reflect larger scale environmental conditions.Comment: 26 pages, 13 figures. ApJ, in pres

Measuring the health systems impact of disease control programmes: a critical reflection on the WHO building blocks framework.

BACKGROUND: The WHO health systems Building Blocks framework has become ubiquitous in health systems research. However, it was not developed as a research instrument, but rather to facilitate investments of resources in health systems. In this paper, we reflect on the advantages and limitations of using the framework in applied research, as experienced in three empirical vaccine studies we have undertaken. DISCUSSION: We argue that while the Building Blocks framework is valuable because of its simplicity and ability to provide a common language for researchers, it is not suitable for analysing dynamic, complex and inter-linked systems impacts. In our three studies, we found that the mechanical segmentation of effects by the WHO building blocks, without recognition of their interactions, hindered the understanding of impacts on systems as a whole. Other important limitations were the artificial equal weight given to each building block and the challenge in capturing longer term effects and opportunity costs. Another criticism is not of the framework per se, but rather how it is typically used, with a focus on the six building blocks to the neglect of the dynamic process and outcome aspects of health systems.We believe the framework would be improved by making three amendments: integrating the missing "demand" component; incorporating an overarching, holistic health systems viewpoint and including scope for interactions between components. If researchers choose to use the Building Blocks framework, we recommend that it be adapted to the specific study question and context, with formative research and piloting conducted in order to inform this adaptation. SUMMARY: As with frameworks in general, the WHO Building Blocks framework is valuable because it creates a common language and shared understanding. However, for applied research, it falls short of what is needed to holistically evaluate the impact of specific interventions on health systems. We propose that if researchers use the framework, it should be adapted and made context-specific

A bibliometric analysis of systematic reviews on vaccines and immunisation.

INTRODUCTION: SYSVAC is an online bibliographic database of systematic reviews and systematic review protocols on vaccines and immunisation compiled by the London School of Hygiene & Tropical Medicine and hosted by the World Health Organization (WHO) through their National Immunization Technical Advisory Groups (NITAG) resource centre (www.nitag-resource.org). Here the development of the database and a bibliometric review of its content is presented, describing trends in the publication of policy-relevant systematic reviews on vaccines and immunisation from 2008 to 2016. MATERIALS AND METHODS: Searches were conducted in seven scientific databases according to a standardized search protocol, initially in 2014 with the most recent update in January 2017. Abstracts and titles were screened according to specific inclusion criteria. All included publications were coded into relevant categories based on a standardized protocol and subsequently analysed to look at trends in time, topic, area of focus, population and geographic location. RESULTS: After screening for inclusion criteria, 1285 systematic reviews were included in the database. While in 2008 there were only 34 systematic reviews on a vaccine-related topic, this increased to 322 in 2016. The most frequent pathogens/diseases studied were influenza, human papillomavirus and pneumococcus. There were several areas of duplication and overlap. DISCUSSION: As more systematic reviews are published it becomes increasingly time-consuming for decision-makers to identify relevant information among the ever-increasing volume available. The risk of duplication also increases, particularly given the current lack of coordination of systematic reviews on vaccine-related questions, both in terms of their commissioning and their execution. The SYSVAC database offers an accessible catalogue of vaccine-relevant systematic reviews with, where possible access or a link to the full-text. CONCLUSIONS: SYSVAC provides a freely searchable platform to identify existing vaccine-policy-relevant systematic reviews. Systematic reviews will need to be assessed adequately for each specific question and quality

Life prediction modeling of solder interconnects for electronic systems

A microstructurally-based computational simulation is presented that predicts the behavior and lifetime of solder interconnects for electronic applications. This finite element simulation is based on an internal state variable constitutive model that captures both creep and plasticity, and accounts for microstructural evolution. The basis of the microstructural evolution is a simple model that captures the grain size and microstructural defects in the solder. The mechanical behavior of the solder is incorporated into the model in the form of time-dependent viscoplastic equations derived from experimental creep tests. The unique aspect of this methodology is that the constants in the constitutive relations of the model are determined from experimental tests. This paper presents the constitutive relations and the experimental means by which the constants in the equations are determined. The fatigue lifetime of the solder interconnects is predicted using a damage parameter (or grain size) that is an output of the computer simulation. This damage parameter methodology is discussed and experimentally validated

The COS-Dwarfs Survey: The Carbon Reservoir Around sub-L* Galaxies

We report new observations of circumgalactic gas from the COS-Dwarfs survey, a systematic investigation of the gaseous halos around 43 low-mass z $\leq$ 0.1 galaxies using background QSOs observed with the Cosmic Origins Spectrograph. From the projected 1D and 2D distribution of C IV absorption, we find that C IV absorption is detected out to ~ 0.5 R$_{vir}$ of the host galaxies. The C IV absorption strength falls off radially as a power law and beyond 0.5 R$_{vir}$, no C IV absorption is detected above our sensitivity limit of ~ 50-100 m$\AA$. We find a tentative correlation between detected C IV absorption strength and star formation, paralleling the strong correlation seen in highly ionized oxygen for L~L* galaxies by the COS-Halos survey. The data imply a large carbon reservoir in the CGM of these galaxies, corresponding to a minimum carbon mass of $\gtrsim$ 1.2$\times 10^6$ $M_\odot$ out to ~ 110 kpc. This mass is comparable to the carbon mass in the ISM and more than the carbon mass currently in stars of these galaxies. The C IV absorption seen around these sub-L* galaxies can account for almost two-thirds of all $W_r$> 100 m$\AA$ C IV absorption detected at low z. Comparing the C IV covering fraction with hydrodynamical simulations, we find that an energy-driven wind model is consistent with the observations whereas a wind model of constant velocity fails to reproduce the CGM or the galaxy properties.Comment: 18 Pages, 11 Figures, ApJ 796 13