2,286 research outputs found
Management of invasive Allee species
In this study, we use a discrete, two-patch population model of an Allee species to examine different methods in managing invasions. We first analytically examine the model to show the presence of the strong Allee effect, and then we numerically explore the model to test the effectiveness of different management strategies. As expected invasion is facilitated by lower Allee thresholds, greater carrying capacities and greater proportions of dispersers. These effects are interacting, however, and moderated by population growth rate. Using the gypsy moth as an example species, we demonstrate that the effectiveness of different invasion management strategies is context-dependent, combining complementary methods may be preferable, and the preferred strategy may differ geographically. Specifically, we find methods for restricting movement to be more effective in areas of contiguous habitat and high Allee thresholds, where methods involving mating disruptions and raising Allee thresholds are more effective in areas of high habitat fragmentation
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Impacts of Exhaust Transfer System Contamination on Particulate Matter Measurements
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On-road gaseous and particulate emissions from GDI vehicles with and without gasoline particulate filters (GPFs) using portable emissions measurement systems (PEMS)
The effect of osteopathic manipulative treatment on length of stay in posterolateral postthoracotomy patients: A retrospective case note study
Objective This study retrospectively evaluated the effect of OMT on length of stay (LOS) in hospitalized posterolateral postthoracotomy patients. Methods Inpatient medical records of patients who received posterolateral thoracotomies with lung resection between 1998 and 2011 were reviewed for demographic data, LOS, thoracotomy surgery data, consultation data excluding osteopathic manipulative medicine, discharge data, and osteopathic manipulative medicine consultation data. Results Thirty-eight patients received posterolateral thoracotomies with lung resection; 23 patients received OMT and 15 did not. The mean (standard deviation) LOS was 11.0 (6.8) days (range, 5–29 days) for those who received OMT and 10.4 (5.5) days (range, 3–22 days) for those who did not (P = .90). Five patients developed postoperative ileus, and all had received OMT. Patients receiving 2 surgical procedures had a longer LOS than those receiving 1 surgical procedure (P = .002). Having a decortication performed during the thoracotomy increased LOS by a mean of 6.4 days (P = .005). Patients admitted directly to the intensive care unit were more likely to receive OMT than those who were not (P = .03). Conclusion While there was no difference in LOS, severity of illness was different between patients who received OMT and those who did not. Patients who developed postoperative ileus and most of those admitted directly to the intensive care unit received OMT, suggesting that severity of illness was greater for those who received OMT. Future studies should include a higher subject number in order to stratify for illness severity and also assess the effect of OMT on postoperative pain
Extracellular Matrix Hydrogel Promotes Tissue Remodeling, Arteriogenesis, and Perfusion in a Rat Hindlimb Ischemia Model.
ObjectiveThis study aimed to examine acellular extracellular matrix based hydrogels as potential therapies for treating peripheral artery disease (PAD). We tested the efficacy of using a tissue specific injectable hydrogel, derived from decellularized porcine skeletal muscle (SKM), compared to a new human umbilical cord derived matrix (hUC) hydrogel, which could have greater potential for tissue regeneration because of its young tissue source age.BackgroundThe prevalence of PAD is increasing and can lead to critical limb ischemia (CLI) with potential limb amputation. Currently there are no therapies for PAD that effectively treat all of the underlying pathologies, including reduced tissue perfusion and muscle atrophy.MethodsIn a rodent hindlimb ischemia model both hydrogels were injected 1-week post-surgery and perfusion was regularly monitored with laser speckle contrast analysis (LASCA) to 35 days post-injection. Histology and immunohistochemistry were used to assess neovascularization and muscle health. Whole transcriptome analysis was further conducted on SKM injected animals on 3 and 10 days post-injection.ResultsSignificant improvements in hindlimb tissue perfusion and perfusion kinetics were observed with both biomaterials. End point histology indicated this was a result of arteriogenesis, rather than angiogenesis, and that the materials were biocompatible. Skeletal muscle fiber morphology analysis indicated that the muscle treated with the tissue specific, SKM hydrogel more closely matched healthy tissue morphology. Short term histology also indicated arteriogenesis rather than angiogenesis, as well as improved recruitment of skeletal muscle progenitors. Whole transcriptome analysis indicated that the SKM hydrogel caused a shift in the inflammatory response, decreased cell death, and increased blood vessel and muscle development.ConclusionThese results show the efficacy of an injectable ECM hydrogel alone as a potential therapy for treating patients with PAD. Our results indicate that the SKM hydrogel improved functional outcomes through stimulation of arteriogenesis and muscle progenitor cell recruitment
Identifying Environmental Health Priorities in Underserved Populations: A Study of Rural Versus Urban Communities
Objectives- Understanding and effectively addressing persistent health disparities in minority communities requires a clear picture of members\u27 concerns and priorities. This study was intended to engage residents in urban and rural communities in order to identify environmental health priorities. Specific emphasis was placed on how the communities: defined the term environment; their perceptions of environmental exposures as affecting their health; specific priorities in their communities; and differences in urban versus rural populations.
Study design- A community-engaged approach was used to develop and implement focus groups and compare environmental health priorities in urban versus rural communities.
Methods- A total of eight focus groups were conducted: four in rural and four in urban communities. Topics included: defining the term environment; how the environment may affect health; and environmental priorities within their communities, using both open discussion and a predefined list. Data were analysed both qualitatively and quantitatively to identify patterns and trends.
Results- There were important areas of overlap in priorities between urban and rural communities; both emphasized the importance of the social environment and shared a concern over air pollution from industrial sources. In contrast, for urban focus groups, abandoned houses and their social and physical sequelae were a high priority while concerns about adequate sewer and water services and road maintenance were high priorities in rural communities.
Conclusions- This study was able to identify environmental health priorities in urban versus rural minority communities. In contrast to some previous risk perception research, the results of this study suggest prioritization of tangible, known risks in everyday life instead of rare, disaster-related events, even in communities that have recently experienced devastating damage from tornadoes. The findings can help inform future efforts to study, understand and effectively address environmental issues, and are particularly relevant to developing effective community-based strategies in vulnerable populations
AXTAR: Mission Design Concept
The Advanced X-ray Timing Array (AXTAR) is a mission concept for X-ray timing
of compact objects that combines very large collecting area, broadband spectral
coverage, high time resolution, highly flexible scheduling, and an ability to
respond promptly to time-critical targets of opportunity. It is optimized for
submillisecond timing of bright Galactic X-ray sources in order to study
phenomena at the natural time scales of neutron star surfaces and black hole
event horizons, thus probing the physics of ultradense matter, strongly curved
spacetimes, and intense magnetic fields. AXTAR's main instrument, the Large
Area Timing Array (LATA) is a collimated instrument with 2-50 keV coverage and
over 3 square meters effective area. The LATA is made up of an array of
supermodules that house 2-mm thick silicon pixel detectors. AXTAR will provide
a significant improvement in effective area (a factor of 7 at 4 keV and a
factor of 36 at 30 keV) over the RXTE PCA. AXTAR will also carry a sensitive
Sky Monitor (SM) that acts as a trigger for pointed observations of X-ray
transients in addition to providing high duty cycle monitoring of the X-ray
sky. We review the science goals and technical concept for AXTAR and present
results from a preliminary mission design study.Comment: 19 pages, 10 figures, to be published in Space Telescopes and
Instrumentation 2010: Ultraviolet to Gamma Ray, Proceedings of SPIE Volume
773
Prototype finline-coupled TES bolometers for CLOVER
CLOVER is an experiment which aims to detect the signature of gravitational
waves from inflation by measuring the B-mode polarization of the cosmic
microwave background. CLOVER consists of three telescopes operating at 97, 150,
and 220 GHz. The 97-GHz telescope has 160 feedhorns in its focal plane while
the 150 and 220-GHz telescopes have 256 horns each. The horns are arranged in a
hexagonal array and feed a polarimeter which uses finline-coupled TES
bolometers as detectors. To detect the two polarizations the 97-GHz telescope
has 320 detectors while the 150 and 220-GHz telescopes have 512 detectors each.
To achieve the target NEPs (1.5, 2.5, and 4.5x10^-17 W/rtHz) the detectors are
cooled to 100 mK for the 97 and 150-GHz polarimeters and 230 mK for the 220-GHz
polarimeter. Each detector is fabricated as a single chip to ensure a 100%
operational focal plane. The detectors are contained in linear modules made of
copper which form split-block waveguides. The detector modules contain 16 or 20
detectors each for compatibility with the hexagonal arrays of horns in the
telescopes' focal planes. Each detector module contains a time-division SQUID
multiplexer to read out the detectors. Further amplification of the multiplexed
signals is provided by SQUID series arrays. The first prototype detectors for
CLOVER operate with a bath temperature of 230 mK and are used to validate the
detector design as well as the polarimeter technology. We describe the design
of the CLOVER detectors, detector blocks, and readout, and present preliminary
measurements of the prototype detectors performance.Comment: 4 pages, 6 figures; to appear in the Proceedings of the 17th
International Symposium on Space Terahertz Technology, held 10-12 May 2006 in
Pari
Apparent correlation of palaeomagnetic intensity and climatic records in deep-sea sediments
Most reports of a correlation between Pleistocene climate and geomagnetic field intensity rely strongly on the assumption that sediment natural remanent magnetic (NRM) intensity provides a record of geomagnetic field strength and is not sensitive to local changes in properties of the sediment. Critical assessment of relevant data presented here and elsewhere from deep-sea sediment cores shows that a pronounced dependence of NRM intensity on sediment composition can occur which implies that this assumption is unlikely to be generally valid. As sediment composition often reflects varying depositional conditions induced by climatic change, the significance of correlations proposed between Pleistocene palaeomagnetism and climatic indicators in deep-sea sediments may be less dramatic than sometimes supposed
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