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San Pietro and Rittenberg (1953) reported that urea appeared to meet all the requirements of a satisfactory tracer. Urea is non toxic, not foreign to the body and it shows an even and rapid distribution throughout the total body water without any physiological effect. For these reasons in addition to its easy and accurate measurement, urea is an ideal candidate tracer to estimate empty body water in vivo. Total body water volume (urea space) can be estimated by dividing the total amount of urea infused by the increase in plasma urea concentration from prior to infusion until 12 or 30 minutes after mean infusion time. Kock and Preston (1973) reported significant relationships between urea space measurements and percentage of empty body fat and water in cattle. However, Andrew et al. (1995) using 21 Holstein cows showed that prediction of empty body water using the urea space technique only explained 31 % of the variation. The objective of this experiment was to use the urea dilution technique to estimate the body composition of lactating dairy cows and produce relationships between urea space and body fat and protein content.
Holstein-Friesian cattle are the predominant breed of dairy cattle in Northern Ireland. Breeding programmes for the Holstein Friesian have focused on improved milk production with little emphasis on functional traits such as fertility or disease resistance. In contrast Norwegian dairy cattle have been bred via a multi-trait selection procedure and there is evidence that problems associated with disease and fertility have tended to decrease in recent years. It is important, however, to investigate possible differences in efficiency of food use and partitioning of nutrients between the two breeds which may offset the potential advantages of improvements in secondary characteristics. Consequently, the objectives of this experiment were firstly to investigate the effects of breed type on the efficiency of utilization and partitioning of nutrients for milk production and secondly to investigate if there are differences in the energy requirement for maintenance and the efficiency of utilization of ME for lactation (kl) between the two breeds.
Because polarization encodes geometrical information about unresolved scattering regions, it provides a unique tool for analyzing the 3-D structures of supernovae (SNe) and their surroundings. SNe of all types exhibit time-dependent spectropolarimetric signatures produced primarily by electron scattering. These signatures reveal physical phenomena such as complex velocity structures, changing illumination patterns, and asymmetric morphologies within the ejecta and surrounding material. Interpreting changes in polarization over time yields unprecedentedly detailed information about supernovae, their progenitors, and their evolution.
Begun in 2012, the SNSPOL Project continues to amass the largest database of time-dependent spectropolarimetric data on SNe. I present an overview of the project and its recent results. In the future, combining such data with interpretive radiative transfer models will further constrain explosion mechanisms and processes that shape SN ejecta, uncover new relationships among SN types, and probe the properties of progenitor winds and circumstellar material.
A multi-faceted, multi-institutional laboratory astrophysics program is carried out at the Livermore electron beam ion trap facility, which is a mature spectroscopic source with unsurpassed controls and capabilities, and an unparalleled assortment of spectroscopic equipment, including a full complement of grating and crystal spectrometers and a 6x6 micro-calorimeter array. Recent results range from the calibration of x-ray diagnostics, including the Fe XVII and Fe XXV emission lines, extensive lists of L-shell ions, the first laboratory simulation and fit of a cometary x-ray emission spectrum, and the discovery of new spectral diagnostics for measuring magnetic field strengths.
The number of cell types required for the construction of a metazoan body plan can serve as an index of morphological (or anatomical) complexity; living metazoans range from four (placozoans) to over 200 (hominids) somatic cell types. A plot of the times of origin of body plans against their cell type numbers suggests that the upper bound of complexity has increased more or less steadily from the earliest metazoans until today, at an average rate of about one cell type per 3 m.y. (when nerve cell types are lumped). Computer models in which increase or decrease in cell type number was random were used to investigate the behavior of the upper bound of cell type number in evolving clades. The models are Markovian; variance in cell type number increases linearly through time. Scaled to the fossil record of the upper bound of cell type numbers, the models suggest that early rates of increase in maximum complexity were relatively high. The models and the data are mutually consistent and suggest that the Metazoa originated near 600 Ma, that the metazoan “explosion” near the Precambrian/Cambrian transition was not associated with any important increase in complexity of body plans, and that important decreases in the upper bound of complexity are unlikely to have occurred.
During airway surgery, the anaesthetist may be required to manipulate or withdraw the endotracheal tube. Traditional surgical head drapes often make access to the tube difficult, therefore limiting control of the airway and risking de-sterilisation of the surgical field. We report a new method of draping for major neck operations that permits easy access to the endotracheal tube while maintaining sterility of the operative field.
Alloys of (AlxM1−x)3Ti where M is V, Cr, Mn, Fe, Co, Nb, W, Fe + Ga or Fe + Ga + Mn were fabricated to form the Ll2 cubic phase, tested for ductility, and characterized by lattice parameter, microstructure, quantitative phase analysis, and phase composition. The elements V, Co, Nb, W, Fe + Ga and Fe + Ga + Mn are hereby newly found Ll2 formers in Al3Ti. Both X-ray diffraction and microprobe analysis were used to identify the phases, their volume fractions and compositions. The amount of ternary addition found in the Ll2 cubic phase varied between 4 and 12 atomic percent. This amount of ternary addition decreased as the atomic radius of the elemental addition increased. Pettifor's Mendeleev number was a useful guide in the selection of elements to form the Ll2 phase but did not correlate strongly with the amount of the ternary addition. For the DO23 phase of Al3Zr, the elements V, Mn, and Co were added to the list of Ni, Cu, Fe, and Cr as elements known to form the Ll2 phase. Little if any ductility was observed in these cubic Ll2 phases which readily cleaved with transgranular failure. To achieve ductility and toughness, more than transformation of these compositions from a lower to a higher symmetry crystal structure will be required.
Optical data over a broad energy range (∼ 0.01 eV to ∼ 6 eV) for a series of La2−xSrxCuO4-δ compounds are obtained in parallel with the Meissner effect and the superconductivity transition temperature, Tc. Two noteworthy trends in the optical spectra are observed as the Sr concentration is increased in small steps from x = 0 to x = 0.3. First is the appearance of a low frequency band in the reflectivity, R, whose strength follows closely the Meissner effect and Tc measured on the same set of samples. The position of the onset of this band is pinned at ∼0.9 eV for all values of x. The origin of this band in R is identified as an absorption process due to an electronic transition with a large oscillator strength. Second is the appearance and disappearance of an intense vibrational mode whose strength also tracks “superconductivity”. This sharp structure in the far infrared is a characteristic vibrational mode associated with the dopant induced electronic state.
Optical reflectance spectra in the range 30–35000 cm-1 and 4–300 K are presented on several YBa2CuxOy phases, as well as different forms of the superconducting YBa2CuxO7−x (polycrystalline pellets, textured pellets with ab-plane oriented surface, and single crystals).
A process for volume production of ultra-low distortion (<200 ppm), thin polyimide membranes on silicon wafers was developed using the RotoEtch™ dynamic fluid confinement tool. A critical advantage of the process is that it exposes the sample to the etching solution over a selected area on one side only, without contacting, wetting, or otherwise contaminating the front surface. This unique feature allows the etching away of a circular portion (over 40 mm diameter) of the backside of a patterned silicon wafer to form a freestanding thin polyimide membrane (<1 μim thick). The polyimide film is patterned prior to wet etching with a sub-micron period grating (200 nm period). The resulting distortion of the grating on the freestanding membrane is less than 200 ppm over the entire membrane area. This process seems ideally suited for instances—like the one above—when immersion, contacting, or contamination of one side of the sample would be impossible or impractical. It also allows backetching finished micro-structures that would otherwise be disturbed or destroyed by immersion in the fluid. Finally, it speeds up the fabrication of freestanding films since it does not require masking or any other form of front-side protection or backside lithographic steps. In this paper we report on a silicon through-etch process based on an HF:HNO3 acid mixture which typically forms membranes in only 10–20 minutes. Since polyimide easily distorts due to excessive heat or mechanical strain, the etching process needs to be carefully controlled. This process is also ideal for forming large membranes of other HF:HNO3-inert materials such as silicon carbide or diamond.
Embedded piezoresistive microcantilever (EPM) sensors were used to detect the presence of the compound estrogen in water samples. The sensor was fabricated with a host material hydrogel (Hypol) functionalized with estrogen antibody. This sensor was able to detect 1 ppm of estrogen in water, responding almost immediately to the estrogen addition, with a full sensor response (saturation) occurring after two minutes of exposure.