An Elastomeric Energy Storage System to Improve Vehicle Efficiency.

Most regenerative braking systems studied hitherto have made use of batteries, tlywheels and hydraulic accumulators. The present study has investigated the use of elastomers for such systems. The ability of elastomers to store large amounts of energy, together with the fact that this energy can be recovered quickly, makes them attractive materials for propulsion devices and inherently simple to engineer. Theoretical and experimental research has shown that the development of an elastomeric regenerative braking system does appear to be technically feasible. The predicted rubber characteristics have been compared with the known characteristics of a conventional engine. The results show that the tractive effort produced by the elastomer is capable of matching the characteristics of the engine considered in this work. Rates of input and output energy have also been calculated to determine the process of energy storage and retrieval throughout a typical driving cycle. The energy store appears to be capable of reproducing many stages of the three driving cycles considered. When there is insufticient energy in the system, power boosts from the conventional engine are required. In order to increase the overall savings achieved by the system, the engine was 'replaced' by one which had force (and therefore power) characteristics of one half of the conventional engine initially considered. It was found that the reduced power engine was sufficient to supply the extra power boosts as required. In addition to reduced engine and brake wear, fuel consumption and emissions have been shown to be drastically reduced. If these values could be achieved in practice, the benefits of such a system are immediately apparent. The potential financial savings available to the car user corresponding to the decrease in fuel consumption would provide a strong incentive. Environmentally the benefits are two fold, firstly the reduction in pollution emissions means cleaner air and has an impact on global warming, and secondly reduced fuel consumption means that fossil fuel reserves may last considerably longer than currently predicted thus reducing the immediate need for alternatives sources

Financial Barriers and Lapses in Treatment and Care of HIV-Infected Adults in a Southern State in the United States

Antiretroviral (ARV) adherence has largely been considered from the perspective of an individual's behavior with less attention given to potential structural causes for lapses in treatment, such as the cost of medications and care. HIV medication expense is typically covered by third party payers. However, private insurance premiums and deductibles may rise, or policies terminated such as with a change in employment. Likewise, a patient's eligibility for publicly funded coverage like state AIDS Drug Assistance Programs (ADAP) or Medicaid can also be lost. We conducted a one-Time survey of a sample of 300 patients receiving HIV care at a single large academic center in the south of United States to examine lapses in HIV therapy due to financial reasons. We found that during the prior year, financial issues including medication cost or coverage led to a lapse in ARVs in 10% (n = 31) of participants. However, of the 42% (n = 125) participants who had been enrolled in ADAP at any time during the prior year, 21% (n = 26) reported an ARV lapse due to problems with ADAP or medication cost. Respondents cited ADAP's required semi-Annual renewal process and other administrative issues as the cause of ARV lapses. The median duration of missed ARVs was 2 weeks (range of <1-23 weeks). Non-HIV medication and transportation to and from clinic costs were also identified as financial burdens to care by respondents. In conclusion, although conducted at a single medical center and one state, this study suggests that a significant minority of HIV-infected patients encounter financial barriers to ARV access, and this is paradoxically more common among those enrolled in the state ADAP. Streamlining, supporting, and simplifying ADAP renewal procedures will likely reduce lapses in ARV adherence and persistence

Decision by sampling

We present a theory of decision by sampling (DbS) in which, in contrast with traditional models, there are no underlying psychoeconomic scales. Instead, we assume that an attribute’s subjective value is constructed from a series of binary, ordinal comparisons to a sample of attribute values drawn from memory and is its rank within the sample. We assume that the sample reflects both the immediate distribution of attribute values from the current decision’s context and also the background, real-world distribution of attribute values. DbS accounts for concave utility functions; losses looming larger than gains; hyperbolic temporal discounting; and the overestimation of small probabilities and the underestimation of large probabilities

Assessment of flatness and symmetry of megavoltage x-ray beam with an electronic portal imaging device (EPID)

Copyright © 2002 ACPSEM. All rights reserved. The document attached has been archived with permission from the publisher.The input/output characteristics of the Wellhofer BIS 710 electronic portal imaging device (EPID) have been investigated to establish its efficacy for periodic quality assurance (QA) applications. Calibration curves have been determined for the energy fluence incident on the detector versus the pixel values. The effect of the charge coupled device (CCD) camera sampling time and beam parameters (such as beam field size, dose rate, photon energy) on the calibration have been investigated for a region of interest (ROI) around the central beam axis. The results demonstrate that the pixel output is a linear function of the incident exposure, as expected for a video-based electronic portal imaging system. The field size effects of the BIS 710 are similar to that of an ion chamber for smaller field sizes up to 10 x 10 cm2. However, for larger field sizes the pixel value increases more rapidly. Furthermore, the system is slightly sensitive to dose rate and is also energy dependent. The BIS 710 has been used in the current study to develop a QA procedure for measurements of flatness and symmetry of a linac x-ray beam. As a two-dimensional image of the radiation field is obtained from a single exposure of the BIS 710, a technique has been developed to calculate flatness and symmetry from a defined radiation area. The flatness and symmetry values obtained are different from those calculated conventionally from major axes only (inplane, crossplane). This demonstrates that the technique can pick up the "cold" and "hot" spots in the analysed area, providing thus more information about the radiation beam. When calibrated against the water tank measurements, the BIS 710 can be used as a secondary device to monitor the x-ray beam flatness and symmetry.G. Liu, T. van Doorn and E. Beza

Thinking about growth : a cognitive mapping approach to understanding small business development

School of Managemen

Prevalence of intellectual disability among eight-year-old children from selected communities in the United States, 2014

Background: Children with intellectual disability (ID), characterized by impairments in intellectual functioning and adaptive behavior, benefit from early identification and access to services. Previous U.S. estimates used administrative data or parent report with limited information for demographic subgroups. Objective: Using empiric measures we examined ID characteristics among 8-year-old children and estimated prevalence by sex, race/ethnicity, geographic area and socioeconomic status (SES) area indicators. Methods: We analyzed data for 8-year-old children in 9 geographic areas participating in the 2014 Autism and Developmental Disabilities Monitoring Network. Children with ID were identified through record review of IQ test data. Census and American Community Survey data were used to estimate the denominator. Results: Overall, 11.8 per 1,000 (1.2%) had ID (IQ ≤ 70), of whom 39% (n = 998) also had autism spectrum disorder. Among children with ID, 1,823 had adaptive behavior test scores for which 64% were characterized as impaired. ID prevalence per 1,000 was 15.8 (95% confidence interval [95% CI], 15.0–16.5) among males and 7.7 (95% CI, 7.2–8.2) among females. ID prevalence was 17.7 (95% CI, 16.6–18.9) among children who were non-Hispanic black; 12.0 (95% CI, 11.1–13.0), among Hispanic; 8.6 (95% CI, 7.1–10.4), among non-Hispanic Asian; and 8.0 (95% CI, 7.5–8.6), among non-Hispanic white. Prevalence varied across geographic areas and was inversely associated with SES. Conclusions: ID prevalence varied substantively among racial, ethnic, geographic, and SES groups. Results can inform strategies to enhance identification and improve access to services particularly for children who are minorities or living in areas with lower SES

Search for Higgs bosons decaying to tautau pairs in ppbar collisions at sqrt(s) = 1.96 TeV

We present a search for the production of neutral Higgs bosons decaying into tautau pairs in ppbar collisions at a center-of-mass energy of 1.96 TeV. The data, corresponding to an integrated luminosity of 5.4 fb-1, were collected by the D0 experiment at the Fermilab Tevatron Collider. We set upper limits at the 95% C.L. on the product of production cross section and branching ratio for a scalar resonance decaying into tautau pairs, and we then interpret these limits as limits on the production of Higgs bosons in the minimal supersymmetric standard model (MSSM) and as constraints in the MSSM parameter space.Comment: 7 pages, 5 figures, submitted to PL

Measurement of three-jet differential cross sections d sigma-3jet / d M-3jet in p anti-p collisions at sqrt(s)=1.96 TeV

We present the first measurement of the inclusive three-jet differential cross section as a function of the invariant mass of the three jets with the largest transverse momenta in an event in p anti-p collisions at sqrt(s) = 1.96 TeV. The measurement is made in different rapidity regions and for different jet transverse momentum requirements and is based on a data set corresponding to an integrated luminosity of 0.7 fb^{-1} collected with the D0 detector at the Fermilab Tevatron Collider. The results are used to test the three-jet matrix elements in perturbative QCD calculations at next-to-leading order in the strong coupling constant. The data allow discrimination between parametrizations of the parton distribution functions of the proton.Comment: 10 pages, 4 figures, 2 tables, submitted to Phys. Lett. B, corrected chi2 values for NNPD

Measurements of inclusive W+jets production rates as a function of jet transverse momentum in ppbar collisions at sqrt{s}=1.96 TeV

This Letter describes measurements of inclusive W (--> e nu) + n jet cross sections (n = 1-4), presented as total inclusive cross sections and differentially in the nth jet transverse momentum. The measurements are made using data corresponding to an integrated luminosity of 4.2 fb-1 collected by the D0 detector at the Fermilab Tevatron Collider, and achieve considerably smaller uncertainties on W +jets production cross sections than previous measurements. The measurements are compared to next-to-leading order perturbative QCD (pQCD) calculations in the n =1-3 jet multiplicity bins and to leading order pQCD calculations in the 4-jet bin. The measurements are generally in agreement with pQCD predictions, although certain regions of phase space are identified where the calculations could be improved

Measurement of spin correlation in ttbar production using dilepton final states

We measure the correlation between the spin of the top quark and the spin of the anti-top quark in (ttbar -> W+ W- b bbar -> l+ nu b l- nubar bbar) final states produced in ppbar collisions at a center of mass energy sqrt(s)=1.96 TeV, where l is an electron or muon. The data correspond to an integrated luminosity of 5.4 fb-1 and were collected with the D0 detector at the Fermilab Tevatron collider. The correlation is extracted from the angles of the two leptons in the t and tbar rest frames, yielding a correlation strength C= 0.10^{+0.45}_{-0.45}, in agreement with the NLO QCD prediction within two standard deviations, but also in agreement with the no correlation hypothesis.Comment: 10 pages, 3 figures, submitted to PL