2,111 research outputs found
“It falls on all our shoulders”: Overcoming Barriers to Delivering Sex Education in West Texas Schools
BACKGROUND: Many racial, socioeconomic, and geographic disparities exist in rates of teen birth and sexually transmitted infections. Increasing access to comprehensive sex education is one risk reduction strategy for these outcomes, yet access to and quality of sex education in schools often falls far below recommended standards, particularly in Texas. The current exploratory study examines barriers to effectively delivering sex education in West Texas schools and identifies strategies to help overcome these barriers. METHODS: In-depth interviews with school leaders and health education professionals (n=4) were conducted to understand teen sexual health needs in West Texas. Interviews were analyzed using descriptive coding, memoing, and quote matrices to interpret the data. RESULTS: Participants identified a number of policy-, organizational-, and interpersonal-level barriers to delivering sex education in public schools. School personnel experienced intense time pressures, a lack of institutional support, and tension with parents. Many expressed a desire to work more collaboratively with parents and participants acknowledged the important role of school health advisory councils (SHACs). CONCLUSIONS: School personnel face complex challenges at multiple levels when attempting to deliver sex education in public schools. Despite these challenges, SHACs represent a valuable opportunity for communities to work collaboratively to improve sex education in public schools
Minimizing Vessel Strikes to Endangered Whales: A Crash Course in Conservation Science and Policy
The North Atlantic right whale is one of the most endangered of all large whales: about 350-400 individuals remain. Species recovery is, in part, contingent on reducing vessel-strike mortality. Our science-based conservation program resulted in three efforts specifically designed to minimize the risk of lethal vessel-strikes of endangered baleen whales without compromising vessel navigation and safety. In Atlantic Canada, the Bay of Fundy Traffic Separation Scheme (TSS) was relocated to reduce the risk of lethal vessel strikes by 90% where the original outbound lane of the TSS intersected the Right Whale Conservation Area, and an Area To Be Avoided (ATBA) adopted for Roseway Basin has demonstrated an 82% reduction in the risk of lethal vessel-strikes. In the Gulf of Maine, the Boston TSS through the Stellwagen Bank National Marine Sanctuary was relocated to reduce the overlap between vessels and endangered baleen whales by ~81% and by ~58% for right whales alone. This rerouting of vessels for whale conservation, as sanctioned by the International Maritime Organization, sets a precedent for national and international marine conservation policy by providing vessels with direct actions they can take to protect endangered whales – both regulated (TSS) and voluntary (ATBA). This demonstrate that despite contentious conditions, effective science-driven policy tools for conservation can be identified, made available, and implemented. The science also provides the quantitative means to measure policy efficacy through monitoring of vessel compliance and, in some cases, can increase compliance through improved real-time communications regarding whale locations in high-risk areas
Mathematical Models and Biological Meaning: Taking Trees Seriously
We compare three basic kinds of discrete mathematical models used to portray
phylogenetic relationships among species and higher taxa: phylogenetic trees,
Hennig trees and Nelson cladograms. All three models are trees, as that term is
commonly used in mathematics; the difference between them lies in the
biological interpretation of their vertices and edges. Phylogenetic trees and
Hennig trees carry exactly the same information, and translation between these
two kinds of trees can be accomplished by a simple algorithm. On the other
hand, evolutionary concepts such as monophyly are represented as different
mathematical substructures are represented differently in the two models. For
each phylogenetic or Hennig tree, there is a Nelson cladogram carrying the same
information, but the requirement that all taxa be represented by leaves
necessarily makes the representation less efficient. Moreover, we claim that it
is necessary to give some interpretation to the edges and internal vertices of
a Nelson cladogram in order to make it useful as a biological model. One
possibility is to interpret internal vertices as sets of characters and the
edges as statements of inclusion; however, this interpretation carries little
more than incomplete phenetic information. We assert that from the standpoint
of phylogenetics, one is forced to regard each internal vertex of a Nelson
cladogram as an actual (albeit unsampled) species simply to justify the use of
synapomorphies rather than symplesiomorphies.Comment: 15 pages including 6 figures [5 pdf, 1 jpg]. Converted from original
MS Word manuscript to PDFLaTe
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The continued high incidence of crime is recognized as being a serious national problem. Much controversy surrounds the estimated effects of policy changes within the Criminal Justice System. The paper presents a methodology for analyzing the effects of possible policy changes in a state's prison/parole system on future prison and parole populations. A simulation model is presented, viewing a prison/parole system as a feedback process for ciminal offenders. Transitions among the states in which an offender might be located, imprisoned, paroled, and discharged, are assumed to be in accordance with a discrete time semi-Markov process. Projected prison and parole populations for sample data and applications of the model are discussed. (Author)http://archive.org/details/prisonparolesyst00and
Numerical simulation of colloidal dispersion filtration: description of critical flux and comparison with experimental results
During filtration via membrane processes, colloids accumulate at the porous surface leading to fouling phenomena. In this study, a rigorous simulation of momentum and mass transfer using CFD modelling has been developed to describe such an accumulation during cross flow filtration. These simulations integrate detailed modeling of physicochemical properties specific to colloidal dispersions (because of the surface interactions (repulsive and attractive) occurring between the colloids particles). These interactions are accounted for via the experimental variation of the colloidal osmotic pressure with volume fraction (associated with a variation in the diffusion coefficient) which are fitted by a relationship integrated into the CFD code. It contains a description of the colloidal phase transition leading to the formation of a condensed phase (deposit or gel layer) from the accumulated dispersed phase (concentration polarization). It is then possible to determine the critical flux which separates filtration conditions below which mass accumulation is reversible (in the dispersed phase) and above which it is irreversible (in the condensed phase). The computed value of critical flux is compared with that determined experimentally for a dispersion of latex particles
The role of sand lances (Ammodytes sp.) in the Northwest Atlantic ecosystem: a synthesis of current knowledge with implications for conservation and management
© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Staudinger, M. D., Goyert, H., Suca, J. J., Coleman, K., Welch, L., Llopiz, J. K., Wiley, D., Altman, I., Applegate, A., Auster, P., Baumann, H., Beaty, J., Boelke, D., Kaufman, L., Loring, P., Moxley, J., Paton, S., Powers, K., Richardson, D., Robbins, J., Runge, J., Smith, B., Spiegel, C., & Steinmetz, H. The role of sand lances (Ammodytes sp.) in the Northwest Atlantic ecosystem: a synthesis of current knowledge with implications for conservation and management. Fish and Fisheries, 00, (2020): 1-34, doi:10.1111/faf.12445.The American sand lance (Ammodytes americanus, Ammodytidae) and the Northern sand lance (A. dubius, Ammodytidae) are small forage fishes that play an important functional role in the Northwest Atlantic Ocean (NWA). The NWA is a highly dynamic ecosystem currently facing increased risks from climate change, fishing and energy development. We need a better understanding of the biology, population dynamics and ecosystem role of Ammodytes to inform relevant management, climate adaptation and conservation efforts. To meet this need, we synthesized available data on the (a) life history, behaviour and distribution; (b) trophic ecology; (c) threats and vulnerabilities; and (d) ecosystem services role of Ammodytes in the NWA. Overall, 72 regional predators including 45 species of fishes, two squids, 16 seabirds and nine marine mammals were found to consume Ammodytes. Priority research needs identified during this effort include basic information on the patterns and drivers in abundance and distribution of Ammodytes, improved assessments of reproductive biology schedules and investigations of regional sensitivity and resilience to climate change, fishing and habitat disturbance. Food web studies are also needed to evaluate trophic linkages and to assess the consequences of inconsistent zooplankton prey and predator fields on energy flow within the NWA ecosystem. Synthesis results represent the first comprehensive assessment of Ammodytes in the NWA and are intended to inform new research and support regional ecosystem‐based management approaches.This manuscript is the result of follow‐up work stemming from a working group formed at a two‐day multidisciplinary and international workshop held at the Parker River National Wildlife Refuge, Massachusetts in May 2017, which convened 55 experts scientists, natural resource managers and conservation practitioners from 15 state, federal, academic and non‐governmental organizations with interest and expertise in Ammodytes ecology. Support for this effort was provided by USFWS, NOAA Stellwagen Bank National Marine Sanctuary, U.S. Department of the Interior, U.S. Geological Survey, Northeast Climate Adaptation Science Center (Award # G16AC00237), an NSF Graduate Research Fellowship to J.J.S., a CINAR Fellow Award to J.K.L. under Cooperative Agreement NA14OAR4320158, NSF award OCE‐1325451 to J.K.L., NSF award OCE‐1459087 to J.A.R, a Regional Sea Grant award to H.B. (RNE16‐CTHCE‐l), a National Marine Sanctuary Foundation award to P.J.A. (18‐08‐B‐196) and grants from the Mudge Foundation. The contents of this paper are the responsibility of the authors and do not necessarily represent the views of the National Oceanographic and Atmospheric Administration, U.S. Fish and Wildlife Service, New England Fishery Management Council and Mid‐Atlantic Fishery Management Council. This manuscript is submitted for publication with the understanding that the United States Government is authorized to reproduce and distribute reprints for Governmental purposes. Any use of trade, firm or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government
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