432 research outputs found

    Patterns of distribution and spatial indicators of ecosystem change based on key species in the Southern Benguela

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    Several commercially and ecologically important species in the southern Benguela have undergone southward and eastward shifts in their distributions over previous decades, most notably the small pelagic fish sardine Sardinops sagax and anchovy Engraulis encrasicolus . Understanding these changes and their implications is essential in implementing an ecosystem approach to fisheries in the southern Benguela and attempting to appreciate the potential impacts of future environmental change. To investigate possible impacts of these shifts at an ecosystem level, distribution maps for before (1985-1991), during (1997-2000) and after (2003-2008) the shift in small pelagic fish were constructed for 14 key species from catch and survey data, and used to calculate spatial indicators including proportion east and west of Cape Agulhas, relative overlap in biomass and area, index of diversity, connectivity. Potential interactions on the south and west coasts were also compared. For several species (redeye; chub mackerel; kingklip; chokka squid; yellowtail), previously unidentified increases in the proportion of biomass east of Cape Agulhas were shown to have occurred over the same period as that of small pelagic fish, although none to the same degree. On average, overlap with small pelagic fish increased over time and overall system connectivity was lowest in the intermediate period, possibly indicating a system under transition. Connectivity declined over time on the west coast while increasing on the east coast. Distributions of other species have changed over time, with the region east of Cape Agulhas becoming increasingly important in terms of potential trophic interaction. Variations in distribution of biomass and structural complexity affect the trophic structure and hence functioning of the system, and implications should be considered when attempting to identify the possible ecosystem impacts of current and future system-level change

    Developing the next generation of dissemination and implementation researchers: Insights from initial trainees

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    BACKGROUND: Dissemination and implementation (D&I) research is a relatively young discipline, underscoring the importance of training and career development in building and sustaining the field. As such, D&I research faces several challenges in designing formal training programs and guidance for career development. A cohort of early-stage investigators (ESI) recently involved in an implementation research training program provided a resource for formative data in identifying needs and solutions around career development. RESULTS: Responses outlined fellows’ perspectives on the perceived usefulness and importance of, as well as barriers to, developing practice linkages, acquiring additional methods training, academic advancement, and identifying institutional supports. Mentorship was a cross-cutting issue and was further discussed in terms of ways it could foster career advancement in the context of D&I research. CONCLUSIONS: Advancing an emerging field while simultaneously developing an academic career offers a unique challenge to ESIs in D&I research. This article summarizes findings from the formative data that outlines some directions for ESIs and provides linkages to the literature and other resources on key points

    Creating a Culture of Voting in Direct and Generalist Practice: Training Field Instructors

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    Social workers have an ethical responsibility to be engaged in policy change, regardless of their practice area or specialization. Voter engagement and the importance of political power through voting is often overlooked in the literature as a valid and important component of social work practice. Creating a culture of nonpartisan voter engagement in practice settings can help empower individuals who have been historically and intentionally disenfranchised from our electoral system. Training for field instructors, faculty, and field staff is a key aspect of voter engagement in social work education. Unfortunately, social work education is unlikely to include substantive content on voter engagement or its connection to social work practice and impact. This article presents one component of a model for integrating voter engagement into social work education: the provision of training for field instructors on nonpartisan voter engagement at two universities over two years. Evaluation findings suggest that pre-existing levels of political efficacy affect the reaction of field instructors to nonpartisan voter engagement training. Furthermore, findings indicate that field instructors who receive voter engagement training are more likely to serve as resources for their students and to consider voter engagement as part of their own practice. We offer evidence on the important role field educators can play in the success of the larger national effort to integrate voter engagement in social work education. Increasing awareness of what social workers, nonprofit, and public agencies are allowed--or even required--to do is a critical first step

    The Case for Gun Policy Reforms in America

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    Debates about gun control often drift towards general arguments about whether guns make us safer or less safe, and gun control is equated with restricting gun ownership. However, with recent Supreme Court decisions overturning laws which ban firearm possession in the District of Columbia and Chicago, current gun control policies in the U.S. do not disarm lawabiding adults over the age of 21. Rather, gun control laws today focus on one or more of four general objectives. These laws aim to:Define conditions that prohibit a person from possessing firearms;Implement regulations to prevent prohibited persons from possessing firearms;Restrict carrying of concealed firearms outside the home; andRegulate the design of firearms to enhance public and personal safety.In this report we draw upon research evidence to suggest how improvements in each of these types of gun policies could enhance public safety in the United States

    Exploring the chemical link between local ellipticals and their high-redshift progenitors

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    We present Keck/MOSFIRE K-band spectroscopy of the first mass-selected sample of galaxies at z2.3z\sim2.3. Targets are selected from the 3D-HST Treasury survey. The six detected galaxies have a mean [NII]λ\lambda6584/Hα\alpha ratio of 0.27±0.010.27\pm0.01, with a small standard deviation of 0.05. This mean value is similar to that of UV-selected galaxies of the same mass. The mean gas-phase oxygen abundance inferred from the [NII]/Hα\alpha ratios depends on the calibration method, and ranges from 12+log(O/H)gas=8.57_{gas}=8.57 for the {Pettini} & {Pagel} (2004) calibration to 12+log(O/H)gas=8.87_{gas}= 8.87 for the {Maiolino} {et~al.} (2008) calibration. Measurements of the stellar oxygen abundance in nearby quiescent galaxies with the same number density indicate 12+log(O/H)stars=8.95_{stars}= 8.95, similar to the gas-phase abundances of the z2.3z\sim2.3 galaxies if the {Maiolino} {et~al.} (2008) calibration is used. This suggests that these high-redshift star forming galaxies may be progenitors of today's massive early-type galaxies. The main uncertainties are the absolute calibration of the gas-phase oxygen abundance and the incompleteness of the z2.3z\sim2.3 sample: the galaxies with detected Hα\alpha tend to be larger and have higher star formation rates than the galaxies without detected Hα\alpha, and we may still be missing the most dust-obscured progenitors.Comment: 7 pages, 5 figures. Accepted for publication in ApJ

    Quiescent Galaxies in the 3D-HST Survey: Spectroscopic Confirmation of a Large Number of Galaxies with Relatively Old Stellar Populations at z~2

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    Quiescent galaxies at z~2 have been identified in large numbers based on rest-frame colors, but only a small number of these galaxies have been spectroscopically confirmed to show that their rest-frame optical spectra show either strong Balmer or metal absorption lines. Here, we median stack the rest-frame optical spectra for 171 photometrically-quiescent galaxies at 1.4 < z < 2.2 from the 3D-HST grism survey. In addition to Hbeta (4861A), we unambiguously identify metal absorption lines in the stacked spectrum, including the G-band (4304A), Mg I (5175A), and Na I (5894A). This finding demonstrates that galaxies with relatively old stellar populations already existed when the universe was ~3 Gyr old, and that rest-frame color selection techniques can efficiently select them. We find an average age of 1.3^0.1_0.3 Gyr when fitting a simple stellar population to the entire stack. We confirm our previous result from medium-band photometry that the stellar age varies with the colors of quiescent galaxies: the reddest 80% of galaxies are dominated by metal lines and have a relatively old mean age of 1.6^0.5_0.4 Gyr, whereas the bluest (and brightest) galaxies have strong Balmer lines and a spectroscopic age of 0.9^0.2_0.1 Gyr. Although the spectrum is dominated by an evolved stellar population, we also find [OIII] and Hbeta emission. Interestingly, this emission is more centrally concentrated than the continuum with L_[OIII] = 1.7 +/- 0.3 x 10^40 erg s^-1, indicating residual central star formation or nuclear activity.Comment: 6 pages, 4 figures, accepted for publication in the Astrophysical Journal Letter

    Climate, Environmental and Socio-Economic Change: Weighing Up the Balance in Vector-Borne Disease Transmission

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    Arguably one of the most important effects of climate change is the potential impact on human health. While this is likely to take many forms, the implications for future transmission of vector-borne diseases (VBDs), given their ongoing contribution to global disease burden, are both extremely important and highly uncertain. In part, this is owing not only to data limitations and methodological challenges when integrating climate-driven VBD models and climate change projections, but also, perhaps most crucially, to the multitude of epidemiological, ecological and socio-economic factors that drive VBD transmission, and this complexity has generated considerable debate over the past 10-15 years. In this review, we seek to elucidate current knowledge around this topic, identify key themes and uncertainties, evaluate ongoing challenges and open research questions and, crucially, offer some solutions for the field. Although many of these challenges are ubiquitous across multiple VBDs, more specific issues also arise in different vector-pathogen systems
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