Environmental Quenching of Low-Mass Field Galaxies

In the local Universe, there is a strong division in the star-forming properties of low-mass galaxies, with star formation largely ubiquitous amongst the field population while satellite systems are predominantly quenched. This dichotomy implies that environmental processes play the dominant role in suppressing star formation within this low-mass regime (${M}_{\star} \sim 10^{5.5-8}~{\rm M}_{\odot}$). As shown by observations of the Local Volume, however, there is a non-negligible population of passive systems in the field, which challenges our understanding of quenching at low masses. By applying the satellite quenching models of Fillingham et al. (2015) to subhalo populations in the Exploring the Local Volume In Simulations (ELVIS) suite, we investigate the role of environmental processes in quenching star formation within the nearby field. Using model parameters that reproduce the satellite quenched fraction in the Local Group, we predict a quenched fraction -- due solely to environmental effects -- of $\sim 0.52 \pm 0.26$ within $1< R/R_{\rm vir} < 2$ of the Milky Way and M31. This is in good agreement with current observations of the Local Volume and suggests that the majority of the passive field systems observed at these distances are quenched via environmental mechanisms. Beyond $2~R_{\rm vir}$, however, dwarf galaxy quenching becomes difficult to explain through an interaction with either the Milky Way or M31, such that more isolated, field dwarfs may be self-quenched as a result of star-formation feedback.Comment: 9 pages, 4 figures, MNRAS accepted version, comments welcome - RIP Ducky...gone but never forgotte

Project risk screening matrix for stream management and restoration

The ‘Project Risk Screening Matrix’ derives from a broader effort to assist US government agency staff in reviewing proposed stream management and restoration projects more efficiently and effectively. The River Restoration Analysis Tool (RiverRAT) developed through this effort provides a thorough, comprehensive and auditable approach to review and evaluation of proposed stream actions and projects (www.restorationreview.com). The matrix was initially developed as the first step in applying the RiverRAT, its purpose being to assist reviewers in assessing the risk to natural resources associated with a particular proposal and matching the intensity of their review to the severity of that risk. Hence, the primary application of the matrix to date has been to identify and screen out low risk projects that may be dealt with expeditiously, and so freeing the time and technical resources needed to allow deep reviews of higher risk projects. A second form of screening emerged from this primary function because the matrix proved adept at identifying the minimum level of site and project characterization required to support initial risk assessment. On this basis, proposals lacking adequate information can also be screened out, being referred back to the proponent with a request for additional information. More recently, new and novel versions of the matrix, featuring modification and refinement of one or both of the original axes, have emerged to widen and refine its application to linear infrastructure (e.g. pipelines, roads, and electrical transmission lines), instream structures (e.g. large wood placement and culvert removal), and pre-application, regulatory, decision-support tools

Project risk screening matrix for stream management and restoration

The ‘Project Risk Screening Matrix’ derives from a broader effort to assist US government agency staff in reviewing proposed stream management and restoration projects more efficiently and effectively. The River Restoration Analysis Tool (RiverRAT) developed through this effort provides a thorough, comprehensive and auditable approach to review and evaluation of proposed stream actions and projects (www.restorationreview.com). The matrix was initially developed as the first step in applying the RiverRAT, its purpose being to assist reviewers in assessing the risk to natural resources associated with a particular proposal and matching the intensity of their review to the severity of that risk. Hence, the primary application of the matrix to date has been to identify and screen out low risk projects that may be dealt with expeditiously, and so freeing the time and technical resources needed to allow deep reviews of higher risk projects. A second form of screening emerged from this primary function because the matrix proved adept at identifying the minimum level of site and project characterization required to support initial risk assessment. On this basis, proposals lacking adequate information can also be screened out, being referred back to the proponent with a request for additional information. More recently, new and novel versions of the matrix, featuring modification and refinement of one or both of the original axes, have emerged to widen and refine its application to linear infrastructure (e.g. pipelines, roads, and electrical transmission lines), instream structures (e.g. large wood placement and culvert removal), and pre-application, regulatory, decision-support tools

Taking Care of Business in a Flash: Constraining the Timescale for Low-Mass Satellite Quenching with ELVIS

The vast majority of dwarf satellites orbiting the Milky Way and M31 are quenched, while comparable galaxies in the field are gas-rich and star-forming. Assuming that this dichotomy is driven by environmental quenching, we use the ELVIS suite of N-body simulations to constrain the characteristic timescale upon which satellites must quench following infall into the virial volumes of their hosts. The high satellite quenched fraction observed in the Local Group demands an extremely short quenching timescale (~ 2 Gyr) for dwarf satellites in the mass range Mstar ~ 10^6-10^8 Msun. This quenching timescale is significantly shorter than that required to explain the quenched fraction of more massive satellites (~ 8 Gyr), both in the Local Group and in more massive host halos, suggesting a dramatic change in the dominant satellite quenching mechanism at Mstar < 10^8 Msun. Combining our work with the results of complementary analyses in the literature, we conclude that the suppression of star formation in massive satellites (Mstar ~ 10^8 - 10^11 Msun) is broadly consistent with being driven by starvation, such that the satellite quenching timescale corresponds to the cold gas depletion time. Below a critical stellar mass scale of ~ 10^8 Msun, however, the required quenching times are much shorter than the expected cold gas depletion times. Instead, quenching must act on a timescale comparable to the dynamical time of the host halo. We posit that ram-pressure stripping can naturally explain this behavior, with the critical mass (of Mstar ~ 10^8 Msun) corresponding to halos with gravitational restoring forces that are too weak to overcome the drag force encountered when moving through an extended, hot circumgalactic medium.Comment: 12 pages, 6 figures; resubmitted to MNRAS after referee report (August 25, 2015

The Portfolio Pension Plan: An Alternative Model for Retirement Security

This chapter describes a proposed new defined benefit (DB) pension design known as a portfolio pension plan. This design falls within a larger category of so-called ‘shared risk’ pension plans. In the United States, shared risk pension plans address a need created by the limitations of existing retirement plan designs. An alternative to existing designs is needed because DB plans to date have concentrated risk on plan sponsors in a way that makes them financially unsustainable in many, if not most, circumstances. Moreover, existing defined contribution (DC) retirement plans impose risk on employees in a way that is challenging for most individuals to manage. In the past, many employers shared risk with employees by providing both a DB and a DC plan. Nevertheless, this chapter argues that a new model can provide an alternative that better serves employers and employees in the United States

Under Pressure: Quenching Star Formation in Low-Mass Satellite Galaxies via Stripping

Recent studies of galaxies in the local Universe, including those in the Local Group, find that the efficiency of environmental (or satellite) quenching increases dramatically at satellite stellar masses below ~ $10^8\ {\rm M}_{\odot}$. This suggests a physical scale where quenching transitions from a slow "starvation" mode to a rapid "stripping" mode at low masses. We investigate the plausibility of this scenario using observed HI surface density profiles for a sample of 66 nearby galaxies as inputs to analytic calculations of ram-pressure and viscous stripping. Across a broad range of host properties, we find that stripping becomes increasingly effective at $M_{*} < 10^{8-9}\ {\rm M}_{\odot}$, reproducing the critical mass scale observed. However, for canonical values of the circumgalactic medium density ($n_{\rm halo} < 10^{-3.5}$${\rm cm}^{-3}$), we find that stripping is not fully effective; infalling satellites are, on average, stripped of < 40 - 70% of their cold gas reservoir, which is insufficient to match observations. By including a host halo gas distribution that is clumpy and therefore contains regions of higher density, we are able to reproduce the observed HI gas fractions (and thus the high quenched fraction and short quenching timescale) of Local Group satellites, suggesting that a host halo with clumpy gas may be crucial for quenching low-mass systems in Local Group-like (and more massive) host halos.Comment: updated version after review, now accepted to MNRAS; Accepted 2016 August 22. Received 2016 August 18; in original form 2016 June 2

Exploring the cultural aspects of compassion in nursing care: a comparative study of Greece and Cyprus

Introduction: It is important to consider the concept of compassionate care within a cultural context in terms of how it might be perceived and demonstrated in practice. People may vary in what constitutes suffering due to variations in their values, culture, needs and understanding. In this paper we report on the findings from data collected from Greek and Greek-Cypriot Nurses during a study which sought to explore similarities and differences between the two countries with regard to perceptions of compassion. Methods: This is an exploratory, cross-sectional descriptive study. The data discussed within this paper have been extracted from a large scale on-line survey involving 15 countries. Greek-Cypriot participants were recruited through local professional organizations and university/college student associations. In Greece, participants were recruited through university associations and social networks. Participants were emailed a link to the survey which was completed on-line. The research tool consisted of 10 open and closed questions. Results: Many similarities were identified between the two groups following their response to the survey, although some small differences were also identified. From the findings of the qualitative data, 3 main themes emerged for both groups of nurses: compassionate communication; awareness of needs; and kindness, whilst a fourth theme was also identified applying mostly to the Greek nurses with regard to factors which might hinder compassion and referring mainly to the effects of economic crisis. Discussion: A number of similarities were identified between the two countries and both countries reported feeling that compassion in nursing is very important, and also stating that they themselves received little compassion from management. However, despite similarities in the perceptions of Greek and Greek-Cypriot nurses, some differences were also identified. Furthermore, our study revealed a greater number of Greek nurses reporting effects of austerity. Conclusion: Greek and Greek Cypriot nurses may differ on how they define compassion but their practical expressions on compassion are very similar. Both countries felt that their own experiences of compassion were most likely to come from colleagues or patients, and most unlikely to come from their managers. There is an urgent need for compassionate leaders within their public health care systems, who will develop organizational cultures which nurture and sustain compassion. This is particularly evident in the case of Greece where we identified a larger number of nurses reporting restraints due to financial crisis

Fractal-like Distributions over the Rational Numbers in High-throughput Biological and Clinical Data

Recent developments in extracting and processing biological and clinical data are allowing quantitative approaches to studying living systems. High-throughput sequencing, expression profiles, proteomics, and electronic health records are some examples of such technologies. Extracting meaningful information from those technologies requires careful analysis of the large volumes of data they produce. In this note, we present a set of distributions that commonly appear in the analysis of such data. These distributions present some interesting features: they are discontinuous in the rational numbers, but continuous in the irrational numbers, and possess a certain self-similar (fractal-like) structure. The first set of examples which we present here are drawn from a high-throughput sequencing experiment. Here, the self-similar distributions appear as part of the evaluation of the error rate of the sequencing technology and the identification of tumorogenic genomic alterations. The other examples are obtained from risk factor evaluation and analysis of relative disease prevalence and co-mordbidity as these appear in electronic clinical data. The distributions are also relevant to identification of subclonal populations in tumors and the study of the evolution of infectious diseases, and more precisely the study of quasi-species and intrahost diversity of viral populations

Osteochondritis Dissecans Development after Bone Contusion of the Knee in the Skeletally Immature: A Case Series

Osteochondritis dissecans (OCD) is thought to be an acquired osteochondral disorder, and its etiology may be multi-factorial. Trauma, both acute and repetitive events, has previously been proposed as a potential cause for OCD development. We present two cases of skeletally immature males who developed a symptomatic OCD lesion following a femoral condyle bone contusion. These cases suggest that an acute traumatic event may lead to the development of OCD of the knee

Evidence of Rapid Phenocryst Growth of Olivine During Ascent in Basalts From the Big Pine Volcanic Field: Application of Olivine‐Melt Thermometry and Hygrometry at the Liquidus

The Quaternary Big Pine (BP) volcanic field in eastern California is notable for the occurrence of mantle xenoliths in several flows. This points to rapid ascent of basalt through the crust and precludes prolonged storage in a crustal reservoir. In this study, the hypothesis of phenocryst growth during ascent is tested for several basalts (13–7 wt% MgO) and shown to be viable. Phenocrysts of olivine and clinopyroxene frequently display diffusion‐limited growth textures, and clinopyroxene compositions are consistent with polybaric crystallization. When the most Mg‐rich olivine in each sample is paired with the whole‐rock composition, resulting Fe2+‐MgKD(olivine‐melt) values (0.31–0.36) match those calculated from literature models (0.32–0.36). Application of a Mg‐ and a Ni‐based olivine‐melt thermometer from the literature, both calibrated on the same experimental data set, leads to two sets of temperatures that vary linearly with whole‐rock MgO wt%. Because the Ni thermometer is independent of water content, it provides the actual temperature at the onset of olivine crystallization (1247–1097°C), whereas the Mg thermometer gives the temperature under anhydrous conditions and thus allows ΔT (=TMg − TNi = depression of liquidus due to water) to be obtained. The average ΔT for all samples is ~59°C, which is consistent with analyzed water contents of 1.5–3.0 wt% in olivine‐hosted melt inclusions from the literature. Because the application of olivine‐melt thermometry/hygrometry at the liquidus only requires microprobe analyses of olivine combined with whole‐rock compositions, it can be used to obtain large global data sets of the temperature and water contents of basalts from different tectonic settings.Plain Language SummaryBasaltic lavas are a window into their mantle source regions, which is why it is important to determine their temperatures and water contents. In this study, a new approach that allows these two parameters to be quantified is demonstrated for basalts from the Big Pine volcanic field, CA. They were targeted because many contain chunks of dense mantle rocks, which precludes storage in a crustal magma chamber and points to direct ascent from the mantle to the surface along fractures. Two hypotheses are proposed, tested, and shown to be viable in this study: (1) olivine crystallized in the basalts during ascent, and (2) the most Mg‐rich olivine analyzed in each basalt represents the first olivine to grow during ascent. This enables the most Mg‐rich olivine to be paired with the whole‐rock composition in the application of olivine‐melt thermometry and hygrometry. The results match those from published, independent studies. The success of this approach paves the way for the attainment of large, high‐quality data sets for basalts from a wide variety of tectonic settings. This, in turn, may allow global variations in mantle temperature and volatile content to be mapped in greater detail and better understood.Key PointsRapid phenocryst growth occurs during ascent in Mg‐rich basalts (some carry mantle xenoliths) from the Big Pine volcanic field, CAThe most Mg‐rich olivine can be paired with the whole‐rock composition to apply olivine‐melt thermometry/hygrometry at the liquidusLarge, high‐quality data sets on the temperature and water content of basalts from various tectonic settings can be obtained by this methodPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/163434/3/ggge22329-sup-0001-2020GC009264-SI.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163434/2/ggge22329.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163434/1/ggge22329_am.pd