802 research outputs found
Barriers, control and identity in health information seeking among African American women
Qualitative research methods were used to examine the role of racial, cultural, and socio-economic group (i.e., communal) identities on perceptions of barriers and control related to traditional and internet resources for seeking health information. Eighteen lower income, African American women participated in training workshops on using the internet for health, followed by two focus groups. Transcripts were analyzed using standardized coding methods. Results demonstrated that participants perceived the internet as a tool for seeking health information, which they believed would empower them within formal healthcare settings. Participants invoked racial, cultural, and socio-economic identities when discussing barriers to seeking health information within healthcare systems and the internet. The findings indicate that the internet may be a valuable tool for accessing health information among lower income African American women if barriers are reduced. Recommendations are made that may assist health providers in improving health information seeking outcomes of African American women
Criterions for condensation-free flow in supersonic tunnels
The results of an investigation of water-vapor condensation shocks in the air passing through supersonic tunnels are presented. Criterions for condensation-free flow are established by correlating experimental observations with the Volmer theory of nuclei formation. Experimental observations were made at Mach numbers up to 2.01. The criterions are presented in a form independent of tunnel-inlet stagnation pressure and are extended theoretically to a Mach number of 4.00. Preliminary evidence of the effect of tunnel size on the criterion is presented
Aerodynamics of Slender Bodies at Mach Number of 3.12 and Reynolds Numbers from 2 x 10(exp 6) to 15 x 10(exp 6) : Body of Revolution with Near-parabolic Forebody and Cylindrical Afterbody
An experimental investigation of the aerodynamic characteristics of a slender, square-based body of revolution was conducted at a Mach number of 3.12 for angles of attack from 0 degree to 10 degrees and for Reynolds numbers from 2 x 10(exp 6) to 15 x 10(exp 6). Boundary-layer measurements at zero angle of attack are compared with several compressible flow formulating for predicting boundary-layer characteristics. Comparison of experimental pressure and force values with theoretical values showed good agreement for low angles of attack. The measured mean skin-friction coefficients agreed well with those predicted by Mangler's transformation for laminar flow over cones
Is there a reliability challenge for logic?
There are many domains about which we think we are reliable. When there is prima facie reason to believe that there is no satisfying explanation of our reliability about a domain given our background views about the world, this generates a challenge to our reliability about the domain or to our background views. This is what is often called the reliability challenge for the domain. In previous work, I discussed the reliability challenges for logic and for deductive inference. I argued for four main claims: First, there are reliability challenges for logic and for deduction. Second, these reliability challenges cannot be answered merely by providing an explanation of how it is that we have the logical beliefs and employ the deductive rules that we do. Third, we can explain our reliability about logic by appealing to our reliability about deduction. Fourth, there is a good prospect for providing an evolutionary explanation of the reliability of our deductive reasoning. In recent years, a number of arguments have appeared in the literature that can be applied against one or more of these four theses. In this paper, I respond to some of these arguments. In particular, I discuss arguments by Paul Horwich, Jack Woods, Dan Baras, Justin Clarke-Doane, and Hartry Field
Reducing youth suicide : systems modelling and simulation to guide targeted investments across the determinants
Background: Reducing suicidal behaviour (SB) is a critical public health issue globally. The complex interplay of social determinants, service system factors, population demographics, and behavioural dynamics makes it extraordinarily difficult for decision makers to determine the nature and balance of investments required to have the greatest impacts on SB. Real-world experimentation to establish the optimal targeting, timing, scale, frequency, and intensity of investments required across the determinants is unfeasible. Therefore, this study harnesses systems modelling and simulation to guide population-level decision making that represent best strategic allocation of limited resources. Methods: Using a participatory approach, and informed by a range of national, state, and local datasets, a system dynamics model was developed, tested, and validated for a regional population catchment. The model incorporated defined pathways from social determinants of mental health to psychological distress, mental health care, and SB. Intervention scenarios were investigated to forecast their impact on SB over a 20-year period. Results: A combination of social connectedness programs, technology-enabled coordinated care, post-attempt assertive aftercare, reductions in childhood adversity, and increasing youth employment projected the greatest impacts on SB, particularly in a youth population, reducing self-harm hospitalisations (suicide attempts) by 28.5% (95% interval 26.3–30.8%) and suicide deaths by 29.3% (95% interval 27.1–31.5%). Introducing additional interventions beyond the best performing suite of interventions produced only marginal improvement in population level impacts, highlighting that ‘more is not necessarily better.’ Conclusion: Results indicate that targeted investments in addressing the social determinants and in mental health services provides the best opportunity to reduce SB and suicide. Systems modelling and simulation offers a robust approach to leveraging best available research, data, and expert knowledge in a way that helps decision makers respond to the unique characteristics and drivers of SB in their catchments and more effectively focus limited health resources
Histopathological screening of Pontogammarus robustoides (Amphipoda), an invader on route to the United Kingdom
Biological invasions may act as conduits for pathogen introduction. To determine which invasive non-native species pose the biggest threat, we must first determine the symbionts (pathogens, parasites, commensals, mutualists) they carry, via pathological surveys that can be conducted in multiple ways (i.e., molecular, pathological, and histological). Whole animal histopathology allows for the observation of pathogenic agents (virus to Metazoa), based on their pathological effect upon host tissue. Where the technique cannot accurately predict pathogen taxonomy, it does highlight pathogen groups of importance. This study provides a histopathological survey of Pontogammarus robustoides (invasive amphipod in Europe) as a baseline for symbiont groups that may translocate to other areas/hosts in future invasions
Seasonal variation of water uptake of a Quercus suber tree in Central Portugal
Hydraulic redistribution (HR) is the phenomenon
where plant roots transfer water between
soil horizons of different water potential. When dry
soil is a stronger sink for water loss from the plant
than transpiration, water absorbed by roots in wetter
soil horizons is transferred toward, and exuded into
dry soil via flow reversals through the roots. Reverse
flow is a good marker of HR and can serve as a useful
tool to study it over the long-term. Seasonal variation
of water uptake of a Quercus suber tree was studied
from late winter through autumn 2003 at Rio Frio
near Lisbon, Portugal. Sap flow was measured in five
small shallow roots (diameter of 3–4 cm), 1 to 2 m
from the tree trunk and in four azimuths and at
different xylem depths at the trunk base, using the
heat field deformation method (HFD). The pattern of
sap flow differed among lateral roots as soil dried with constant positive flow in three roots and reverse
flow in two other roots during the night when
transpiration ceased. Rain modified the pattern of
flow in these two roots by eliminating reverse flow
and substantially increasing water uptake for transpiration
during the day. The increase in water uptake in
three other roots following rain was not so substantial.
In addition, the flux in individual roots was correlated
to different degrees with the flux at different radial
depths and azimuthal directions in trunk xylem. The
flow in outer trunk xylem seemed to be mostly
consistent with water movement from surface soil
horizons, whereas deep roots seemed to supply water
to the whole cross-section of sapwood. When water
flow substantially decreased in shallow lateral roots
and the outer stem xylem during drought, water flow
in the inner sapwood was maintained, presumably due
to its direct connection to deep roots. Results also
suggest the importance of the sap flow sensor
placement, in relation to sinker roots, as to whether
lateral roots might be found to exhibit reverse flow
during drought. This study is consistent with the
dimorphic rooting habit of Quercus suber trees in
which deep roots access groundwater to supply
superficial roots and the whole tree, when shallow
soil layers were dry
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