247 research outputs found

    Using EMCS Data to Document and Improve Air Handler Performance

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    Traditionally, energy monitoring and control systems (EMCS) have been used, as the name implies, to monitor and control heating, ventilating and air conditioning systems, however, this paper will identify other benefits of an EMCS. Recording EMCS data on a periodic basis, typically once an hour, and analyzing it using a commercial off the shelf database program has proven to be an effective method to improve and document indoor air quality, energy savings; and provide continuous controls commissioning and performance diagnostics. Identification of system problems is the key to having an efficient and reliable EMCS. Once identified they can be scheduled to be repaired and system integrity will be maintained. Specific diagnostic and functionality programming include: Identifying leaking heating and cooling control valves Identifying simultaneous heating and cooling operation Identifying proper air side economizer operation Identifying faulty components Identifying cooling and heating system problems Calculating ventilation rates Calculating energy wastes and savings Finally, using EMCS data in the non-traditional manner has saved thousands of dollars in operation and maintenance costs by providing a hands-off "tool" to diagnose air handler performance

    MRI measures of middle cerebral artery diameter in conscious humans during simulated orthostasis.

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    BACKGROUND AND PURPOSE: The relationship between middle cerebral artery (MCA) flow velocity (CFV) and cerebral blood flow (CBF) is uncertain because of unknown vessel diameter response to physiological stimuli. The purpose of this study was to directly examine the effect of a simulated orthostatic stress (lower body negative pressure [LBNP]) as well as increased or decreased end-tidal carbon dioxide partial pressure (P(ET)CO(2)) on MCA diameter and CFV. METHODS: Twelve subjects participated in a CO(2) manipulation protocol and/or an LBNP protocol. In the CO(2) manipulation protocol, subjects breathed room air (normocapnia) or 6% inspired CO(2) (hypercapnia), or they hyperventilated to approximately 25 mm Hg P(ET)CO(2) (hypocapnia). In the LBNP protocol, subjects experienced 10 minutes each of -20 and -40 mm Hg lower body suction. CFV and diameter of the MCA were measured by transcranial Doppler and MRI, respectively, during the experimental protocols. RESULTS: Compared with normocapnia, hypercapnia produced increases in both P(ET)CO(2) (from 36+/-3 to 40+/-4 mm Hg, P CONCLUSIONS: Under the conditions of this study, changes in MCA diameter were not detected. Therefore, we conclude that relative changes in CFV were representative of changes in CBF during the physiological stimuli of moderate LBNP or changes in P(ET)CO(2)

    What can mixed-species flock movement tell us about the value of Amazonian secondary forests? Insights from spatial behavior

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    The value of secondary forest for rain forest species remains an important question for conservation in the 21st century. Here, we describe the spatial behavior of understory mixed species flocks in a heterogeneous landscape in central Amazonia. Understory mixed species flocks represent a diverse, highly organized component of the rich Amazonian avifauna. We recorded movements within 26 flock home ranges in primary forest, secondary forest, interfaces between forest types, and forest fragments. We describe frequency and movement orientation in relation to forest edges, movement patterns and proportion of use between secondary and primary forest, the relation between home range sizes and vegetation height, and home range configuration. Flocks visited only a small portion of forest edges, and showed a tendency for moving parallel to edges next to less developed secondary forest. Movement patterns in secondary forests did not show significant differences compared to primary forests. Time spent in secondary forests increased in proportion to mean canopy height. Flocks were consistently present in secondary forests where vegetation height averaged over 15 m, but home ranges were nearly twice as large compared to primary forest. Home range limits tended to be aligned with disturbed vegetation, essentially rearranging a territorial configuration normally adjusted by topography. The spatial behavior of this important subset of the Amazonian avifauna shows that secondary forests are tolerated above a certain development threshold, but perceived as sub optimal habitat until canopy height closely matches primary forests

    A High-Resolution Sensor Network for Monitoring Glacier Dynamics

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    This paper provides an overview of a wide area wireless sensor network that was deployed on the calving front of the Helheim Glacier in Greenland during the summer of 2013. The purpose of the network was to measure the flow rate of the glacier using accurate satellite positioning data. The challenge in this extreme environment was to collect data in real time at the calving edge of the glacier. This was achieved using a solar powered 2.4-GHz Zigbee wireless sensor network operated in a novel hybrid cellular/mesh access architecture consisting of ice nodes communicating with base stations placed on the rock adjacent to the glacier. This highly challenging transmission environment created substantial signal outage conditions, which were successfully mitigated by a radio network diversity scheme. The network development and measurement campaign were highly successful yielding significant results on glacial dynamics associated with climate change

    X-ray scattering study of two length scales in the critical fluctuations of CuGeO3

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    The critical fluctuations of CuGeO3_3 have been measured by synchrotron x-ray scattering, and two length scales are clearly observed. The ratio between the two length scales is found to be significantly different along the aa axis, with the aa axis along the surface normal direction. We believe that such a directional preference is a clear sign that surface random strains, especially those caused by dislocations, are the origin of the long length scale fluctuations.Comment: 5 pages, 4 figures, submitted to PR

    Evidence of biological recovery from gross pollution in English and Welsh rivers over three decades

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    Uncertainty around the changing ecological status of European rivers reflects an evolving array of anthropogenic stressors, including climate change. Although previous studies have revealed some recovery from historical pollution in the 1990s and early-2000s, there are contrasting trends among pollutants across Europe and recovery may have even stalled or been reversed. To provide more contemporary evidence on trends and status, here we investigate changes in English and Welsh river macroinvertebrate communities over almost 30 years (1991–2019) using a network of nearly 4000 survey locations. Analysis comprised: i) trends in taxonomic and functional richness, community composition and ecological traits, ii) gains, losses and turnover of taxa, and the overall homogeneity of macroinvertebrate communities nationally, and iii) an exploration of how temporal trends varied with catchment characteristics. Taxonomic richness increased, primarily in the 1990s, whilst a shift towards pollution-sensitive taxa continued throughout the study period, accompanied by a growing prevalence in traits such as preferences for fast-flowing conditions, coarser substrata, and ‘shredding’ or ‘scraping’ feeding strategies. Changes consistent with improvement occurred in both urbanised and agricultural catchments, but were more pronounced in urban rivers as they gained pollution sensitive taxa that were otherwise more prevalent in rural rivers. Overall, these results indicate continuing biological recovery from organic pollution, consistent with national scale trends in water quality. Results reemphasise the importance of looking at multiple facets of diversity, with periods of near-constant richness disguising changes in taxonomic and functional composition. Whilst this national-scale picture is broadly positive, we highlight the need to investigate more local variations or pollutants that depart from this aggregate picture

    Impact of a negative breast biopsy on subsequent breast self-examination practice

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    Women who practice breast-self examination (BSE) occasionally detect breast lumps that are ultimately biopsied and found to be benign. This research examined the impact of a negative breast biopsy on subsequent BSE practice. A total of 655 women comprised three study groups: 83 women who discovered their breast problem by BSE; 179 women whose lump was identified by an individual/procedure in the health care system; and 393 women with no history of breast problems. Telephone interviews determined BSE practice for 6-month intervals prior to, and after, the benign biopsy experience. Among previously-regular practitioners, 21% of the self-discovered group and 16% of those whose lump was discovered in the health care system reduced their BSE practice below the recommended monthly interval following the benign biopsy. In contrast, among initiallynonregular practitioners, 29% of the self-discovered group, and 25% of the health care system group subsequently became regular BSE practitioners. Possible explanations are offered for these opposite shifts in BSE regularity, and some practical suggestions are provided for health care professionals who counsel women following a benign biopsy experience.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27726/1/0000118.pd

    Epitaxial growth of high quality ZnS films on sapphire and silicon by pulsed laser deposition

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    We report for the first time, epitaxial growth of high-quality ZnS films on sapphire and silicon substrates, using pulsed laser deposition. X-ray diffraction results show that at all growth temperatures from 200°C to 680°C, epitaxial wurtzite (002) ZnS films have been successfully grown on (1012) sapphire and (001) silicon substrates. X-ray diffraction data yield full width at half maximum 2theta values of 0.13° for as-grown samples, compared with 28 values or 0.09° and 0.08° for the bare sapphire and silicon substrates respectively

    A Comparison of Polarization Observables in Electron Scattering from the Proton and Deuteron

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    Recoil proton polarization observables were measured for both the p(e⃗\vec {\rm e},e′p⃗ ^\prime\vec{\rm p}\,) and d(e⃗\vec {\rm e},e′p⃗ )^\prime\vec{\rm p}\,)n reactions at two values of Q2^2 using a newly commissioned proton Focal Plane Polarimeter at the M.I.T.-Bates Linear Accelerator Center. The hydrogen and deuterium spin-dependent observables DℓℓD_{\ell\ell} and DℓtD_{{\ell}t}, the induced polarization PnP_n and the form factor ratio GEp/GMpG^p_E/G^p_M were measured under identical kinematics. The deuterium and hydrogen results are in good agreement with each other and with the plane-wave impulse approximation (PWIA).Comment: 9 pages, 1 figure; accepted by Phys. Rev. Let
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