3,218 research outputs found
Development of geometric specifications for a small female anthropomorphic test device pelvis
Target surface geometry for the small female anthropomorphic test device pelvis was predicted by a statistical pelvis geometry model developed through analysis of medical imaging data. The resulting geometry was compared to the Hybrid III small female pelvis geometry and an estimate of female pelvis geometry obtained by length scaling the midsize male pelvis based on bispinous breadth. Differences were found in the shape of the pubic rami, ischial tuberosities, and anterior superior iliac wings between the small female pelvis model and the Hybrid III pelvis, which may affect interactions with seat belts and vehicle structures.National Highway Traffic Safety Administrationhttp://deepblue.lib.umich.edu/bitstream/2027.42/117574/1/103243.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/117574/4/103243-1.pdfDescription of 103243.pdf : This file has been superceded. The new file, current as of June 20, 2016, is named 103243-1.pdf.Description of 103243-1.pdf : Final report; supercedes all versions downloaded prior to June 20, 2016
Lessons from the Front Lines: Factors that Contribute to Turnover among Youth Development Workers
Motivated, competent Youth Development Workers (YDW’s ) are essential to effective youth outreach programs. This study explores factors affecting job turnover among Youth Development Workers (YDW’s) through detailed direct observation and interviews of six YDW’s in four organizations and a group interview with eight different YDW’s. YDW stressors included few resources, high need among youth, paperwork, excessive responsibilities, burnout/cynicism, miscommunication with supervisors, personal financial strain and lack of job security. Workers identified needs for appreciation, support from superiors, opportunities to advance, experienced mentors, resources and role definition. For programs to be effective and minimize turnover, YDW’s require resources, mentorship, role definition and appreciation
Developing parametric human models representing various vulnerable populations in motor vehicle crashes
Children, small female, elderly, and obese occupants are vulnerable populations and may sustain increased risk of death and serious injury in motor-vehicle crashes compared with mid-size young male occupants. Unfortunately, current injury assessment tools do not account for immature and growing body structures for children, nor the body shape and composition changes that are thought make female/aging/obese adults more vulnerable. The greatest opportunity to broaden crash protection to encompass all vehicle occupants lies in improved, parametric human models that can represent a wide range of human attributes. In this study, a novel approach to develop such models is proposed. The method includes 1) developing statistical skeleton and human body surface contour models based on medical images and body scan data using Mimics and a series of statistical methods, and 2) linking the statistical geometry model to a baseline human finite element (FE) model through an automated mesh morphing algorithm using radial basis functions, so that the FE model can represent population variability. Examples of using this approach to develop parametric pediatric head model, adult thorax and lower extremity models, and whole-body human models representing various populations were represented. The method proposed in this study enables future safety design optimizations targeting at various vulnerable populations that cannot be considered with current injury assessment tools.http://deepblue.lib.umich.edu/bitstream/2027.42/113667/1/103204.pdf-
Development and validation of statistical models of femur geometry for use with parametric finite element models
Statistical models from a previous study that predict male and female femur geometry as functions of age, body mass index (BMI), and femur length were updated as part of an effort to develop lower-extremity finite element models with geometries that are parametric with subject characteristics. The process for updating these models involved extracting femur geometry from clinical CT scans of an additional 8 men and 36 women (previous models used CT scans from 62 men and 36 women for a new total of 70 men and 72 women), using all of the scans for fitting a template finite element femur mesh to the surface geometry of each patient, and then programmatically determining thickness at each nodal location. Principal component analysis was then performed on the thickness and geometry nodal coordinates, and linear regression models were developed to predict principal component scores as functions of age, BMI, and femur length. The results from the updated models were compared to the previous study, and the only improvement was in the R2 value for the female models (0.74 to 0.82). The largest differences between the original models and the previous models occurred in the ends of the femur, where the largest errors in model predictions occurred.National Highway Traffic Safety Administrationhttp://deepblue.lib.umich.edu/bitstream/2027.42/116208/1/103222.pdfDescription of 103222.pdf : Final repor
Inhaled PGE1 in neonates with hypoxemic respiratory failure: two pilot feasibility randomized clinical trials.
BackgroundInhaled nitric oxide (INO), a selective pulmonary vasodilator, has revolutionized the treatment of neonatal hypoxemic respiratory failure (NHRF). However, there is lack of sustained improvement in 30 to 46% of infants. Aerosolized prostaglandins I2 (PGI2) and E1 (PGE1) have been reported to be effective selective pulmonary vasodilators. The objective of this study was to evaluate the feasibility of a randomized controlled trial (RCT) of inhaled PGE1 (IPGE1) in NHRF.MethodsTwo pilot multicenter phase II RCTs are included in this report. In the first pilot, late preterm and term neonates with NHRF, who had an oxygenation index (OI) of ≥15 and <25 on two arterial blood gases and had not previously received INO, were randomly assigned to receive two doses of IPGE1 (300 and 150 ng/kg/min) or placebo. The primary outcome was the enrollment of 50 infants in six to nine months at 10 sites. The first pilot was halted after four months for failure to enroll a single infant. The most common cause for non-enrollment was prior initiation of INO. In a re-designed second pilot, co-administration of IPGE1 and INO was permitted. Infants with suboptimal response to INO received either aerosolized saline or IPGE1 at a low (150 ng/kg/min) or high dose (300 ng/kg/min) for a maximum duration of 72 hours. The primary outcome was the recruitment of an adequate number of patients (n = 50) in a nine-month-period, with fewer than 20% protocol violations.ResultsNo infants were enrolled in the first pilot. Seven patients were enrolled in the second pilot; three in the control, two in the low-dose IPGE1, and two in the high-dose IPGE1 groups. The study was halted for recruitment futility after approximately six months as enrollment targets were not met. No serious adverse events, one minor protocol deviation and one pharmacy protocol violation were reported.ConclusionsThese two pilot RCTs failed to recruit adequate eligible newborns with NHRF. Complex management RCTs of novel therapies for persistent pulmonary hypertension of the newborn (PPHN) may require novel study designs and a longer period of time from study approval to commencement of enrollment.Trial registrationCLINICALTRIALS.GOV: Pilot one: NCT number: 00598429 registered on 10 January 2008. Last updated: 3 February 2011. Pilot two: NCT number: 01467076 17 October 2011. Last updated: 13 February 2013
The In Situ Signature of Cyclotron Resonant Heating
The dissipation of magnetized turbulence is an important paradigm for
describing heating and energy transfer in astrophysical environments such as
the solar corona and wind; however, the specific collisionless processes behind
dissipation and heating remain relatively unconstrained by measurements. Remote
sensing observations have suggested the presence of strong temperature
anisotropy in the solar corona consistent with cyclotron resonant heating. In
the solar wind, in situ magnetic field measurements reveal the presence of
cyclotron waves, while measured ion velocity distribution functions have hinted
at the active presence of cyclotron resonance. Here, we present Parker Solar
Probe observations that connect the presence of ion-cyclotron waves directly to
signatures of resonant damping in observed proton-velocity distributions. We
show that the observed cyclotron wave population coincides with both flattening
in the phase space distribution predicted by resonant quasilinear diffusion and
steepening in the turbulent spectra at the ion-cyclotron resonant scale. In
measured velocity distribution functions where cyclotron resonant flattening is
weaker, the distributions are nearly uniformly subject to ion-cyclotron wave
damping rather than emission, indicating that the distributions can damp the
observed wave population. These results are consistent with active cyclotron
heating in the solar wind
Adolescent Medicine at the Crossroads: A Review of Fellowship Training and Recommendations for Reform
This report examines the current state of adolescent medicine fellowship programs -- including the supply and recruitment of fellows; the nature and content of clinical, research, and leadership training; and the institutional and financial challenges facing training programs today -- and offers recommendations for building the field. The report is based on findings from the first comprehensive national survey of adolescent medicine fellowship program directors, conducted in the spring of 2007 by Incenter Strategies. The document also presents selected findings from two other Incenter Strategies’ surveys conducted in 2007: one of pediatric residency program directors and the other of adolescent medicine faculty responsible for the one-month pediatric residency rotation. In addition, the report presents findings from key informant interviews and an extensive literature review
Graviton Cosmology in Universal Extra Dimensions
In models of universal extra dimensions, gravity and all standard model
fields propagate in the extra dimensions. Previous studies of such models have
concentrated on the Kaluza-Klein (KK) partners of standard model particles.
Here we determine the properties of the KK gravitons and explore their
cosmological implications. We find the lifetimes of decays to KK gravitons, of
relevance for the viability of KK gravitons as dark matter. We then discuss the
primordial production of KK gravitons after reheating. The existence of a tower
of KK graviton states makes such production extremely efficient: for reheat
temperature T_RH and d extra dimensions, the energy density stored in gravitons
scales as T_RH^{2+3d/2}. Overclosure and Big Bang nucleosynthesis therefore
stringently constrain T_RH in all universal extra dimension scenarios. At the
same time, there is a window of reheat temperatures low enough to avoid these
constraints and high enough to generate the desired thermal relic density for
KK WIMP and superWIMP dark matter.Comment: 19 pages, 1 figur
An examination of the relationship of governance structure and performance: Evidence from banking companies in Bangladesh
Corporate governance has become increasingly important in developed and developing countries just after a series of corporate scandals and failures in a number of countries. Corporate governance structure is often viewed as a means of corporate success despite prior studies reveal mixed, somewhere conflicting and ambiguous, and somewhere no relationship between governance structure and performance. This study empirically investigates the relationship between corporate governance mechanisms and financial performance of listed banking companies in Bangladesh by using two multiple regression models. The study reveals that a good number of companies do not comply with the regulatory requirements indicating remarkable shortfall in corporate governance practice. The companies are run by the professional managers having no duality and no ownership interest for which they are compensated by high remuneration to curb agency conflict. Apart from some inconsistent relationship between some corporate variables, the corporate governance mechanisms do not appear to have significant relationship with financial performances. The findings reveal an insignificant negative impact or somewhere no impact of independent directors and non-independent non-executive directors on the level of performance that strongly support the concept that the managers are essentially worthy of trust and earn returns for the owners as claimed by stewardship theory. The study provides support for the view that while much emphasis on corporate governance mechanisms is necessary to safeguard the interest of stakeholders; corporate governance on its own, as a set of codes or standards for corporate conformance, cannot make a company successful. Companies need to balance corporate governance mechanisms with performance by adopting strategic decision and risk management with the efficient utilization of the organization’s resources
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