140 research outputs found
Engaging Disconnected Young People in Education and Work
Project Rise served 18- to 24-year-olds who lacked a high school diploma or the equivalent and had been out of school, out of work, and not in any type of education or training program for at least six months. After enrolling as part of a group (or cohort) of 25 to 30 young people, Project Rise participants were to engage in a 12-month sequence of activities centered on case management, classroom education focused mostly on preparation for a high school equivalency certificate, and a paid part-time internship that was conditional on adequate attendance in the educational component. After the internship, participants were expected to enter unsubsidized employment, postsecondary education, or both. The program was operated by three organizations in New York City; one in Newark, New Jersey; and one in Kansas City, Missouri
On-Chip Thermoelectric Hotspot Cooling
Increased power density and non-uniform heat dissipation present a thermal
management challenge in modern electronic devices. The non-homogeneous heating
in chips results in areas of elevated temperature, which even if small and localized,
limit overall device performance and reliability. In power electronics, hotspot heat
fluxes can be in excess of 1kW/cm2. Although novel package-level and chip-level
cooling systems capable of removing the large amounts of dissipated heat are under
development, such “global” cooling systems typically reduce the chip temperature
uniformly, leaving the temperature non-uniformity unaddressed. Thus, advanced
hotspot cooling techniques, which provide localized cooling to areas of elevated heat
flux, are required to supplement the new “global” cooling systems and unlock the full
potential of cutting-edge power devices. Thermoelectric coolers have previously been
demonstrated as an effective method of producing on-demand, localized cooling for
semiconductor photonic and logic devices. The growing need for the removal of
localized hotspots has turned renewed attention to on-chip thermoelectric cooling,
seeking to raise the maximum allowable heat flux of thermoelectrically-cooled
semiconductor device hotspots.
This dissertation focused on the numerical and empirical determination of the
operational characteristics and performance limits of two specific thermoelectric
methods for high heat flux hotspot cooling: monolithic thermoelectric hotspot cooling
and micro-contact enhanced thermoelectric hotspot cooling. The monolithic cooling
configuration uses the underlying electronic substrate as the thermoelectric material,
eliminating the need for a discrete cooler and its associated thermal interface resistance.
Micro-contact enhanced cooling uses a contact structure to concentrate the cooling
produced by the thermoelectric module, enabling the direct removal of kW/cm2 level
heat fluxes from on-chip hotspots. To facilitate empirical validation of on-chip
thermoelectric coolers and characterization of advanced thin film thermoelectric
coolers, it was found necessary to develop a novel laser heating system, using a high power laser and short-focal length optics. The design and use of this illumination
system, capable of creating kW/cm2-level, mm-sized hotspots, will also be described
Teen Distracted Reality an Interactive Virtual Education (D.R.I.V.E.): Experience and Impact on Teenage Drivers
Introduction: In 2013, 2,163 teens in the United States ages 16–19 were killed and 243,243 were treated in emergency departments for injuries from motor vehicle crashes. distracted driving (i.e. texting, loud music, or phone conversations) and impaired driving (driving under the influence) play a role in these motor vehicle crashes. Prevention efforts aimed at high-risk teenager driving behavior may encourage safe driving habits.
Methods: The Teen D.R.I.V.E. program is a mobile driving simulator that provides teenagers with distracted and impaired driving scenarios. We administered anonymous surveys from April 2015-April 2016 to obtain demographic data and evaluate the program’s impact on their driving behavior. We retrospectively analyzed survey responses using univariate and multivariate statistical analysis.
Results: A total of 1374 participants in the survey, however, 50 did not respond to the driving experience portion of the survey. Most participants (70%) were between 16-17 years of age years old and 51% were males. A majority (76%) of respondents had driving experience (26% permit, and 46% license) or had attended a driver’s education course (67%). After experiencing the simulation respondents felt that the consequences of driving distracted (53%) and driving impaired (61%) were worse than previously expected. In addition, participants said that they would never drive distracted (70%) or drive impaired (90%). A majority of participants (72%) feel that simulation is the most effective way to teach driving related topics.
Conclusion: Teen D.R.I.V.E. offers a valuable experience to teenagers, teaching them about the dangers of driving distracted and impaired. Participants are likely to never drive impaired compared or distracted. Most teenagers feel simulation teaches these driving lessons most effectively
Atomic Oxygen Erosion Yield Prediction for Spacecraft Polymers in Low Earth Orbit
The ability to predict the atomic oxygen erosion yield of polymers based on their chemistry and physical properties has been only partially successful because of a lack of reliable low Earth orbit (LEO) erosion yield data. Unfortunately, many of the early experiments did not utilize dehydrated mass loss measurements for erosion yield determination, and the resulting mass loss due to atomic oxygen exposure may have been compromised because samples were often not in consistent states of dehydration during the pre-flight and post-flight mass measurements. This is a particular problem for short duration mission exposures or low erosion yield materials. However, as a result of the retrieval of the Polymer Erosion and Contamination Experiment (PEACE) flown as part of the Materials International Space Station Experiment 2 (MISSE 2), the erosion yields of 38 polymers and pyrolytic graphite were accurately measured. The experiment was exposed to the LEO environment for 3.95 years from August 16, 2001 to July 30, 2005 and was successfully retrieved during a space walk on July 30, 2005 during Discovery s STS-114 Return to Flight mission. The 40 different materials tested (including Kapton H fluence witness samples) were selected specifically to represent a variety of polymers used in space as well as a wide variety of polymer chemical structures. The MISSE 2 PEACE Polymers experiment used carefully dehydrated mass measurements, as well as accurate density measurements to obtain accurate erosion yield data for high-fluence (8.43 1021 atoms/sq cm). The resulting data was used to develop an erosion yield predictive tool with a correlation coefficient of 0.895 and uncertainty of +/-6.3 10(exp -25)cu cm/atom. The predictive tool utilizes the chemical structures and physical properties of polymers to predict in-space atomic oxygen erosion yields. A predictive tool concept (September 2009 version) is presented which represents an improvement over an earlier (December 2008) version
Are Goods for Guns Good for the Community? An Update of a Community Gun Buyback Program
BACKGROUND: Gun violence remains a leading cause of death in the United States. Community gun buyback programs provide an opportunity to dispose of extraneous firearms. The purpose of this study was to understand the demographics, motivation, child access to firearms and household mental illness of buyback participants in hopes of improving the program\u27s effectiveness.
METHODS: A 2015 Injury Free Coalition for Kids gun buyback program which collaborated with local police departments was studied. We administered a 23-item questionnaire survey to gun buyback participants assessing demographic characteristics, motivation for relinquishing firearms, child firearm accessibility, and mental illness/domestic violence history.
RESULTS: A total of 186 individuals from Central/Western Massachusetts turned in 339 weapons. Participants received between 75 in gift cards dependent on what type of gun was turned in, with an average cost of $41/gun. A total of 109 participants (59%) completed the survey. Respondents were mostly white (99%), male (90%) and first-time participants in the program (85.2%). Among survey respondents, 54% turned in firearms for safety reasons . Respondents reported no longer needing/wanting their weapons (47%) and approximately one in eight participants were concerned the firearm(s) were accessible to children. Most respondents (87%) felt the program encouraged neighborhood awareness of firearm safety. Three out of every five participants reported that guns still remained in their homes, additionally; 21% where children could potentially access them and 14% with a history of mental illness/suicide/domestic violence in the home.
CONCLUSIONS: Gun buybacks can provide a low-cost means of removing unwanted firearms from the community. Most participants felt their homes were safer after turning in the firearm(s). In homes still possessing guns, emphasis on secure gun storage should continue increasing the safety of children and families. The results of this survey also provided new insights into the association between mental illness/suicide and gun ownership.
LEVEL OF EVIDENCE: Level III, Prognostic and Epidemiological
Potential resolution to the doping puzzle in iron pyrite: Carrier type determination by Hall effect and thermopower
Pyrite FeS2 has outstanding potential as an earth-abundant, low-cost, nontoxic photovoltaic, but underperforms dramatically in solar cells. While the full reasons for this are not clear, one certain factor is the inability to understand and control doping in FeS2. This is exemplified by the widely accepted but unexplained observation that unintentionally doped FeS2 single crystals are predominantly n type, whereas thin films are p type. Here we provide a potential resolution to this “doping puzzle,” arrived at via Hall effect, thermopower, and resistivity measurements on a large set of FeS2 single crystals and films that span five orders of magnitude in mobility. The results reveal three main findings. First, in addition to crystals, the highest mobility thin films in this study are shown to be definitively n type, from both Hall effect and thermopower. Second, as mobility decreases an apparent crossover to p type occurs, first in thermopower, then in Hall measurements. This can be understood, however, in terms of the crossover from diffusive to hopping transport that is clearly reflected in resistivity. Third, universal behavior is found for both crystals and films, suggesting a common n dopant, possibly sulfur vacancies. We thus argue that n-type doping is facile in FeS2 films, that apparent p-type behavior in low mobility samples can be an artifact of hopping, and that the prevailing notion of predominantly p-type films must be revised. These conclusions have deep implications, both for interpretation of prior work on FeS2 solar cells and for the design of future studies
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Baseline Repeated Measures from Controlled Human Exposure Studies: Associations between Ambient Air Pollution Exposure and the Systemic Inflammatory Biomarkers IL-6 and Fibrinogen
Introduction: Systemic inflammation may be one of the mechanisms mediating the association between ambient air pollution and cardiovascular morbidity and mortality. Interleukin-6 (IL-6) and fibrinogen are biomarkers of systemic inflammation that are independent risk factors for cardiovascular disease. Objective: We investigated the association between ambient air pollution and systemic inflammation using baseline measurements of IL-6 and fibrinogen from controlled human exposure studies. Methods: In this retrospective analysis we used repeated-measures data in 45 nonsmoking subjects. Hourly and daily moving averages were calculated for ozone, nitrogen dioxide, sulfur dioxide, and particulate matter ≤ 2.5 μm in aerodynamic diameter (PM2.5). Linear mixed-model regression determined the effects of the pollutants on systemic IL-6 and fibrinogen. Effect modification by season was considered. Results: We observed a positive association between IL-6 and O3 [0.31 SD per O3 interquartile range (IQR); 95% confidence interval (CI), 0.08–0.54] and between IL-6 and SO2 (0.25 SD per SO2 IQR; 95% CI, 0.06–0.43). We observed the strongest effects using 4-day moving averages. Responses to pollutants varied by season and tended to be higher in the summer, particularly for O3 and PM2.5. Fibrinogen was not associated with pollution. Conclusions: This study demonstrates a significant association between ambient pollutant levels and baseline levels of systemic IL-6. These findings have potential implications for controlled human exposure studies. Future research should consider whether ambient pollution exposure before chamber exposure modifies IL-6 response
Pelagic calcium carbonate production and shallow dissolution in the North Pacific Ocean
Funding was provided by NSF Grants OCE1220600 and OCE1220302 awarded to JA and WB, respectively, MINECO PID2020-113526RB-I00, the Generalitat de Catalunya MERS (#2017 SGR-1588) awarded to PZ and NERC grant NE/N011716/1 awarded to JR.Planktonic calcifying organisms play a key role in regulating ocean carbonate chemistry and atmospheric CO2. Surprisingly, references to the absolute and relative contribution of these organisms to calcium carbonate production are lacking. Here we report quantification of pelagic calcium carbonate production in the North Pacific, providing new insights on the contribution of the three main planktonic calcifying groups. Our results show that coccolithophores dominate the living calcium carbonate (CaCO3) standing stock, with coccolithophore calcite comprising ~90% of total CaCO3 production, and pteropods and foraminifera playing a secondary role. We show that pelagic CaCO3 production is higher than the sinking flux of CaCO3 at 150 and 200 m at ocean stations ALOHA and PAPA, implying that a large portion of pelagic calcium carbonate is remineralised within the photic zone; this extensive shallow dissolution explains the apparent discrepancy between previous estimates of CaCO3 production derived from satellite observations/biogeochemical modeling versus estimates from shallow sediment traps. We suggest future changes in the CaCO3 cycle and its impact on atmospheric CO2 will largely depend on how the poorly-understood processes that determine whether CaCO3 is remineralised in the photic zone or exported to depth respond to anthropogenic warming and acidification.Publisher PDFPeer reviewe
Effects on mortality of a nutritional intervention for malnourished HIV-infected adults referred for antiretroviral therapy: a randomised controlled trial.
Malnourished HIV-infected African adults are at high risk of early mortality after starting antiretroviral therapy (ART). We hypothesized that short-course, high-dose vitamin and mineral supplementation in lipid nutritional supplements would decrease mortality
TGF-β1 modulates microglial phenotype and promotes recovery after intracerebral hemorrhage
Intracerebral hemorrhage (ICH) is a devastating form of stroke that results from the rupture of a blood vessel in the brain, leading to a mass of blood within the brain parenchyma. The injury causes a rapid inflammatory reaction that includes activation of the tissue-resident microglia and recruitment of blood-derived macrophages and other leukocytes. In this work, we investigated the specific responses of microglia following ICH with the aim of identifying pathways that may aid in recovery after brain injury. We used longitudinal transcriptional profiling of microglia in a murine model to determine the phenotype of microglia during the acute and resolution phases of ICH in vivo and found increases in TGF-β1 pathway activation during the resolution phase. We then confirmed that TGF-β1 treatment modulated inflammatory profiles of microglia in vitro. Moreover, TGF-β1 treatment following ICH decreased microglial Il6 gene expression in vivo and improved functional outcomes in the murine model. Finally, we observed that patients with early increases in plasma TGF-β1 concentrations had better outcomes 90 days after ICH, confirming the role of TGF-β1 in functional recovery from ICH. Taken together, our data show that TGF-β1 modulates microglia-mediated neuroinflammation after ICH and promotes functional recovery, suggesting that TGF-β1 may be a therapeutic target for acute brain injury
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