LaCl3:Ce coincidence signatures to calibrate gamma-ray detectors

Calibrating the gamma-ray detection efficiency of radiation detectors in a field environment is difficult under most circumstances. To counter this problem we have developed a technique that uses a Cerium doped Lanthanum-Tri-Chloride (LaCl₃:Ce) scintillation detector to provide gated gammas (Guillot-Noël et al. (1999) [1] and van Loef et al. (2001) [2]). Exploiting the inherent radioactivity of the LaCl₃:Ce due to the long-lived radioactive isotope ¹³⁸La (t_1/2=1.06×10¹¹ yr) allows the use of the 788 and 1436 keV gammas as a measure of efficiency. In this paper, we explore the effectiveness of using the beta-gamma coincidences radiation LaCl₃:Ce detector to calibrate the energy and efficiency of a number of gamma-ray detectors.     

Reproductive status of Holstein and Jersey cows in the United States

Reproductive information since 1995 from the USDA national dairy database was used to calculate yearly Holstein and Jersey means for days to first breeding after calving (DFB), 70-d nonreturn rate, conception rate (CR), number of breedings per lactation (NB), interval between first and last breedings during the lactation, days to last breeding after calving (DLB), pregnancy rate (PR), calving interval (CI), and interval between consecutive breedings. Data were from nearly 20 million breedings during >8 million lactations of >5 million cows in >23,000 herds. Means were also calculated for some traits by parity and breeding number for both breeds and by geographical region and synchronization status for Holsteins. The DFB declined for Holsteins from 92 d in 1996 to 85 d in 2007; the trend in yearly differences was not as consistent for Jerseys. First- and all-breeding 70-d nonreturn rate declined 5 to 9 percentage units over time. First- and all-breeding CR declined 2 to 4 percentage units. The DFB were longer for later parities of Holsteins than for early parities. Second- and third-breeding CR were sometimes 1 to 2 percentage units above first-breeding CR for Holsteins but lower (1 to 7 percentage units) for Jerseys. The CR within breeding number declined across parities for both breeds. The NB increased by 0.3 to 0.4 breedings over time but remained constant (2.5 or 2.6 breedings) across parities for Holsteins and increased (from 2.2 to 2.4 breedings) for Jerseys. Holstein DFB were fewest in the Northwest (78 d) and greatest in the Mountain region (92 d). Regional CR was highest for the Northeast and Southwest (33%) and lowest for the Southeast (26%); NB was fewest for the Northeast (2.3) and greatest for the Southeast (2.7). Mean DLB was fewest for the Southwest (127 d) and greatest for the Mountain region (157 d); CI was shortest for the Southwest (406 d) and longest for the Mideast (434 d). Mean PR was highest for the Southwest (28.3%) and lowest for the Mideast and Southeast (22.2%). Use of timed artificial insemination following synchronized estrus appears to have reduced DFB, lowered CR, and increased NB while reducing DLB and CI. However, synchronized breeding was not a primary cause of Holstein regional differences for reproductive traits. Since 2002, phenotypic performance for CR, DLB, and CI as well as genetic merit for daughter PR have stopped their historical declines and started to improve.     

The ‘sub-trigger’ crisis: An economic analysis of flexible stock policies

This paper investigates the value of international cooperation during an oil supply disruption. The International Energy Agency provides the aegis for energy cooperation among the industrialized countries, but only an enormous disruption would ‘trigger’ the Agency's emergency mechanism. Smaller (‘sub-trigger’) disruptions have occurred three times in the past decade, and twice, in 1973–1974, and again in 1979, the result was havoc in the international oil markets and substantial economic damage. General consensus credits oil inventory accumulation with exacerbating these shocks and decumulation with averting similar problems during the 1980 disruption. The paper employs a small short-run econometric model of the oil market to examine inventory behaviour and to test coordinated government stockpile drawdowns (termed ‘flexible stock policies’) which have been proposed to address these issues. Impacts on GNP are obtained by solving the oil market model simultaneously with an econometric model of the US macro-economy.     

Chemical vapor deposition of Pb1−xLaxTiO3

Abstract

We report chemical vapor deposition (CVD) of PbLaTiO₃ films for integrated pyroelectric devices. Pb(thd)₂, La(thd)₃ and Ti(O-Pr)₂(thd)₂ were introduced to the reactor via a single liquid precursor solution that is vaporized. Substrate temperatures were approximately 535°C and post deposition annealing was not used. Films were deposited on fused silica and Pt metallized Si substrates. The liquid delivery technique permitted excellent composition control and films on fused silica were predominantly [100] oriented with trace amounts of [110] and [111] present. Pyroelectricity for 0.7μm thick films deposited on Pt metallized Si was measured using a modified Byer-Roundi technique and pyroelectric coefficients as high as 90 nC/cm²·K were observed. The high crystalline quality and pyroelectric properties are attributed to the excellent composition control afforded by the liquid delivery CVD technique.     

Endocrine control of fat mobilization in the isolated fat cells of cold-exposed rats

Adipose tissue in rats maintained at normal ambient temperature grows by a mixture of cell proliferation and lipid deposition in the early growth stage of the rat. In the mature rat, the tissue grows primarily by lipid deposition, mitotic activity being significantly decreased. When the rat is acclimated to 5 C, growth of adipose tissue is less than that of rats maintained at normal ambient temperature. Furthermore, growth of adipose tissue in the 5 C rat occurs through a mixture of cell proliferation and lipid deposition throughout the body weight range studied. The differences in tissue growth were taken into consideration in measuring the stimulatory effect of norepinephrine on lipolysis and reesterification of isolated fat cells. The results indicate that the cell size affects the lipolytic response; the larger the cell the less sensitive it is. Fat cells from cold-acclimated rats are more sensitive to the lipolytic action of norepinephrine, independent of differences in cell size. On the other hand, reesterification is not affected by cell size, nor by exposure of the rat to cold     

The earth is highly significantly round (p?

Hubbard  Raymond 《Canadian Metallurgical Quarterly》1995,50(12):1098a

Iodination of docosahexaenoic acid by lactoperoxidase and thyroid gland in vitro: Formation of an lodolactone

In the presence of iodide, hydrogen peroxide and lactoperoxidase, docosahexaenoic acid (22∶6ω3) was converted into iodinated compounds. The major product was identified as 5-iodo-4-hydroxy-7, 10,13,16,19-docosapentaenoic acid, γ-lactone, on the basis of¹²⁵I incorporation, mass spectrometry, chemical modifications and proton nuclear magnetic resonance spectroscopy. Iodolactonization of docosahexaenoic acid occurred in the rat thyroid in vitro and was inhibited by the peroxidase inhibitor methimazole. These data indicate that formation of an idolactone constitutes one pathway of docosahexaenoic acid metabolism which could be expressed in tissues containing an iodide peroxidase.     

Comparison of solvent-inaccessible cores of homologous proteins: definitions useful for protein modelling

The three-dimensional structures of 41 homologous proteins (belongingto eight families) were compared by pairwise superposition.A subset of "core" residues was defined as those whose sidechains have <7% of their surface exposed to solvent. Thissubset has significantly higher sequence identity and lowerroot mean square (RMS) carbon separation than for all topologicallyequivalent residues in the structure, when members of a proteinfamily are superposed. For such superpositions the relationshipbetween RMS distance and percentage sequence identity of thissubset of residues is similar to that for all equivalent residues,although some variation is observed between families of proteinswhich are predominantly ß sheet and those which aremainly helix. The definition of a structurally more conservedcore may be ueful in model building proteins from an homologousfamily. The RMS differences of coordinates of structures ofproteins with identical sequences are found to be related tothe resolutions of the structures.     

DIFFUSION IN NON-IONIC AND IONIC POLYMER SOLUTIONS: EFFECTS OF SHEAR RATE AND POLYMER CONCENTRATION

Diffusion coefficients for ferricyanide ions in aqueous polymer solutions have been calculated from laminar flow mass transfer data obtained in a concentric annulus apparatus by the electrochemical voltammetric method. The electrolyte solutions containing one to five percent polyvinyl alcohol or polyacrylic acid were pumped through the annulus. Flow was longitudinal, and the shear rate ranged from 7 to 800 s-1 The diffusion coefficient for ferricyanide in the polymer solutions depended on polymer concentration in a different way for the non-ionic (polyvinyl alcohol) solutions compared to the polyelectrolyte (polyacrylic acid) solutions. Over the range of concentrations studied, the diffusion coefficient as a function of polymer concentration for polyacrylic acid solutions reached a minimum, increased to a maximum, and then decreased slightly.The polyvinyl alcohol data showed minimum and maximum but no decrease, and the minimum occurred at a higher polymer concentration. For each type of solution, the diffusion coefficient decreased from five to twenty percent as the shear rate was increased from 100 to 800 s-1.The diffusion data can be related to polymer molecule uncoiling and stretching in the flowing solution and to solvation of the molecules present.