3,998 research outputs found
TB171: Investigations into the Potential of Measuring Biodiversity in Maine\u27s Forests with Forest Inventory and Analysis (FIA) Data
We present here the results of our initial effort to use FIA data to assess biodiversity in Maine\u27s forests. Biodiversity is a complex issue and, from the start, it was apparent that the FIA data are inadequate for examining all facets of biodiversity. Nevertheless, the FIA provides the most comprehensive and detailed data on Maine\u27s forests and can be used to measure some indicators of forest biodiversity, in particular those related to tree species and stand characteristics.https://digitalcommons.library.umaine.edu/aes_techbulletin/1047/thumbnail.jp
Normalised Root Mean Square and Amplitude of Sidebands of Vibration Response as Tools for Gearbox Diagnosis
Quick assessment of the condition of gearboxes used in helicopters is a safety requirement. One of the most widely used helicopter on-board-mounted condition monitoring system these days is the Health and Usage Monitoring System. It has been specifically designed to monitor the condition of all safety-critical components operating in the helicopter through calculation of so-called condition indicators (CIs) - signal processing routines designed to output a single number that represents the condition of the monitored component. Among number of available parameters, there is a couple of CIs that over the years of testing have earned a reputation of being the most reliable measures of the gear tooth condition. At the same time, however, it has been observed that in some cases, those techniques do not properly indicate the deteriorating condition with the propagation of a gear tooth fault with the period of operation. Hence, three more robust methods have been suggested, which are discussed in this article
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Complexes of triphenylphosphine oxide with lanthanide bromides
The reaction between hydrated lanthanide bromides and triphenylphosphine oxide in 1:3 and 1:4 ratios in ethanol gave a series of complexes [LnBr2(Ph3PO)4]Br (Ln = Pr, Nd, Gd, Tb, Er, Yb, Lu) which contain ethanol and water in the lattice, regardless of the ratio of reactants used. The single crystal x-ray structures of [NdBr2(Ph3PO)4]Br, [GdBr2(Ph3PO)4]Br and [YbBr2(Ph3PO)4]Br have been determined and have an octahedral geometry about the metal ion. Analysis of the bond distances shows that the Ln-O and Ln-Br distance change in accord with the lanthanide contraction, but the non bonded Ln....P distances and the Ln-O-P angles differ significantly for the Yb complex. Conductivity and variable temperature 31P NMR measurements in dichloromethane indicate that the complexes dissolve as [LnBr2(Ph3PO)4]+ for the lighter lanthanides with further ionisation becoming progressively more important for the heavier metals. In methanol more extensive dissociation is apparent. The electrospray mass spectra obtained from methanol solution show [LnBr2(Ph3PO)4]+ is present in high abundance in the gas phase with other species formed due to ligand redistribution, ionisation and solvolysis
Fitting measured evapotranspiration data to the FAO56 dual crop coefficient method
The FAO-56 publication of the UN Food and Agriculture Organization contains guidelines on constructing and applying a ‘dual crop coefficient’ method to characterize the behavior of evapotranspiration (ET) on a day to day basis. The dual crop coefficient (Kc) method substantially improves the ability to fit simulated with measured data, as compared to the ‘single’ Kc method, by partitioning evaporation from soil (Es) from transpiration from vegetation. This permits the separate estimation of Es when there are known wetting events from precipitation and irrigation and assists in explaining behavior of measured data. The application of the dual Kc method is relatively straight forward, especially when applied using the straight-line segment method for the basal Kc curve, Kcb. Illustrations are given on fitting the dual Kc method and Kcb curve to daily ET data for irrigated and rainfed corn crops near Mead, Nebraska measured by eddy covariance and sensitivity to various soil and root zone parameters. Assessment of transferring Kcb curve parameters to other fields and years indicates that soil and root zone parameters are relatively transferrable with little modification, whereas lengths of the four crop growth stages do vary from year to year due to differences in cultivar type and possibly differences in weather
The Glaciochemistry of Snowpits from Quelccaya Ice Cap, Peru, 1982
We present glaciochemical data from a pilot study of two snow-pits from Quelccaya ice cap, Peruvian Andes. These are the first samples to be analyzed from Quelccaya for nitrate and sulfate by ion chromatography (IC), for nitrate-plus-nitrite, reactive silicate and reactive iron by colorimetry, and for sodium by atomic absorption spectrophotometry. The 3 m pits used in this study represent a one year record of mass accumulation and the 29 samples collected provide the first glaciochemical data from this area which can be compared with glaciochemical studies from other locations.
Reactive iron, reactive silicate and sodium, and the profiles of \u3e0.63µm microparticles from Thompson and others (1984) are coincident, suggesting that transport and deposition into this area of each species are controlled by similar processes. The common source is probably local, resulting from crustaI weathering. In general, the reactive silicate values are lower than those observed in other alpine glacier ice. The highest sulfate and nitrate values were observed in the upper few centimeters of the snow-pit. Most of the sulfate concentrations were less than 3 µM and are similar to values obtained for fresh surface snows from Bolivia (Stallard and Edmond 1981). Since biological gaseous emissions are thought to be the major source of sulfur and nitrogen to the atmosphere over the Amazon basin, the sulfate and nitrate fluctuations may be due to seasonal biological input and/or seasonal shifts in wind direction bringing material to Quelccaya.
With only one exception, the colorimetric nitrate-plus-nitrite data were higher than the IC nitrate data. Unfortunately, the IC analyses were conducted 81 d after the colorimetric analyses. The difference between the two data sets could be attributable to the following; (I) the colorimetric technique may yield erroneously high results as suggested for polar ice by Herron (1982), (2) the IC technique yields erroneously low results due, in part, to the possible exclusion of nitrite concentrations, and/or (3) nitrite was lost via biological removal during the 81 d period before the IC analyses. If the IC data are correct, the mean nitrate value is O.4 µM (n = 29). This value is similar to those reported from pre-industrial aged polar ice (Herron 1982). If the colorimetric mean value (1.1 µM) is correct, it is similar to colorimetrically determined values from other high-elevation alpine ice (Lyons and Mayewski 1983)
Comparison of Measured and FAO-56 Modeled Evaporation from Bare Soil
This paper evaluates how well the FAO-56 style soil water evaporation model simulates measurements of evaporation (E) from bare soil. Seven data sets were identified from the literature and in all but one case, the individuals who took the measurements were contacted and they provided the writers with specific weather and soils data for model input. Missing weather and soils data were obtained from online sources or from the National Climatic Data Center. Simulations for three possible variations of soil data were completed and compared. The measured and the FAO-56 simulated E/ETo and cumulative evaporation trends and values were similar. Specifically, the average evaporation weighted percent difference between the measured and the simulated cumulative evaporation was between –7.5 and –0.5%. This evaluation suggests model accuracy of about ±15% with the use of sound weather data and a fairly generalized understanding of soil properties in the location being evaluated
Matter-wave bistability in coupled atom-molecule quantum gases
We study the matter-wave bistability in coupled atom-molecule quantum gases,
in which heteronuclear molecules are created via an interspecies Feshbach
resonance involving either two-species Bose or two-species Fermi atoms at zero
temperature. We show that the resonant two-channel Bose model is equivalent to
the nondegenerate parametric down-conversion in quantum optics, while the
corresponding Fermi model can be mapped to a quantum optics model that
describes a single-mode laser field interacting with an ensemble of
inhomogeneously broadened two-level atoms. Using these analogy and the fact
that both models are subject to the Kerr nonlinearity due to the two-body
s-wave collisions, we show that under proper conditions, the population in the
molecular state in both models can be made to change with the Feshbach detuning
in a bistable fashion.Comment: 6 pages, 5 figure
The Prevalence of Healthcare Associated Infections Among Adult Inpatients at Nineteen Large Australian Acute-care Public Hospitals: A Point Prevalence Survey
Background
Australia does not have a national healthcare associated infection (HAI) surveillance program. Only one HAI point prevalence study has been undertaken in 1984. The objective of this study was to estimate the burden of healthcare associated infection (HAI) in acute adult inpatients in Australia. Methods
A cross sectional point prevalence study (PPS) was conducted in a sample of large acute care hospitals. All data were collected by two trained Research Assistants. Surveillance methodology was based on the European Centre for Disease Prevention and Control (ECDC) PPS Protocol with variation in the sampling method in that only acute inpatients ≥ 18 years old were included. ECDC HAI definitions were applied. Results
Data was collected between August and November 2018. A total of 2767 patients from 19 hospitals were included in the study. The median age of patients was 67, and 52.9% of the sample were male. Presence of a multi-drug resistant organism was documented for 10.3% of the patients. There were 363 HAIs present in 273 patients. The prevalence of patients with a HAI was 9.9% (95%CI: 8.8–11.0). Hospital prevalence rates ranged from 5.7% (95%CI:2.9–11.0) to 17.0% (95%CI:10.7–26.1). The most common HAIs were surgical site infection, pneumonia and urinary tract infection, comprising 64% of all HAIs identified. Conclusion
This is the first HAI PPS to be conducted in Australia in 34 years. The prevalence rate is higher than the previous Australian study and that reported by the ECDC, however differences in methodology limit comparison. Regular, large scale HAI PPS should be undertaken to generate national HAI data to inform and drive national interventions
Gene expression profiling to study racial differences after heart transplantation.
BackgroundThe basis for increased mortality after heart transplantation in African Americans and other non-Caucasian racial groups is poorly defined. We hypothesized that increased risk of adverse events is driven by biologic factors. To test this hypothesis in the Invasive Monitoring Attenuation through Gene Expression (IMAGE) study, we determined whether the event rate of the primary outcome of acute rejection, graft dysfunction, death, or retransplantation varied by race as a function of calcineurin inhibitor (CNI) levels and gene expression profile (GEP) scores.MethodsWe determined the event rate of the primary outcome, comparing racial groups, stratified by time after transplant. Logistic regression was used to compute the relative risk across racial groups, and linear modeling was used to measure the dependence of CNI levels and GEP score on race.ResultsIn 580 patients monitored for a median of 19 months, the incidence of the primary end point was 18.3% in African Americans, 22.2% in other non-Caucasians, and 8.5% in Caucasians (p < 0.001). There were small but significant correlations of race and tacrolimus trough levels to the GEP score. Tacrolimus levels were similar among the races. Of patients receiving tacrolimus, other non-Caucasians had higher GEP scores than the other racial groups. African American recipients demonstrated a unique decrease in expression of the FLT3 gene in response to higher tacrolimus levels.ConclusionsAfrican Americans and other non-Caucasian heart transplant recipients were 2.5-times to 3-times more likely than Caucasians to experience outcome events in the Invasive Monitoring Attenuation through Gene Expression study. The increased risk of adverse outcomes may be partly due to the biology of the alloimmune response, which is less effectively inhibited at similar tacrolimus levels in minority racial groups
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