4,188 research outputs found
CLIC Waveguide Damped Accelerating Structure Studies
Studies of waveguide damped 30 GHz accelerating structures for multibunching in CLIC are described. Frequency discriminated damping using waveguides with a lowest cutoff frequency above the fundamental but below the higher order modes was considered. The wakefield behavior was investigated using time domain MAFIA computations over up to 20 cells and for frequencies up to 150 GHz. A configuration consisting of four T-cross-sectioned waveguides per cell reduces the transverse wake below 1% at typical CLIC bunch spacings
A very High Gradient Test of a 30 GHz Single-Cell Cavity
In order to extend the available range of data on achievable accelerating gradients and pulse lengths at the CLIC (Compact Linear Collider) frequency of 30 GHz, a single-cell resonant cavity has been high-gradient tested in the CLIC Test Facility, CTFII. The cavity was excited by a 4 ns long bunched electron beam, resulting in a field pulse with a steep rise, followed by an exponential decay with a 1/e time of 25 ns (corresponding to a loaded Q of 3800). The cavity operated without breakdown at a peak accelerating gradient of 290 MV/m, with operation progressively less stable with increasing gradient. At about 400 MV/m the cavity broke down on every pulse. For this condition the cavity surface was subject to a surface electric field in excess of 750 MV/m
New Maser Emission from Nonmetastable Ammonia in NGC 7538. II. Green Bank Telescope Observations Including Water Masers
We present new maser emission from ^{14}NH_3 (9,6) in NGC 7538. Our
observations include the known spectral features near v_LSR = -60 km/s and -57
km/s and several more features extending to -46 km/s. In three epochs of
observation spanning two months we do not detect any variability in the ammonia
masers, in contrast to the >10-fold variability observed in other ^{14}NH_3
(9,6) masers in the Galaxy over comparable timescales. We also present
observations of water masers in all three epochs for which emission is observed
over the velocity range -105 km/s < v_LSR < -4 km/s, including the highest
velocity water emission yet observed from NGC 7538. Of the remarkable number of
maser species in IRS 1, H_2O and, now, ^{14}NH_3 are the only masers known to
exhibit emission outside of the velocity range -62 km/s < v_LSR < -51 km/s.
However, we find no significant intensity or velocity correlations between the
water emission and ammonia emission. We also present a non-detection in the
most sensitive search to date toward any source for emission from the CC^{32}S
and CC^{34}S molecules, indicating an age greater than \approx 10^4 yr for IRS
1-3. We discuss these findings in the context of embedded stellar cores and
recent models of the region.Comment: 7 pages, 4 figures, 3 tables; accepted to AJ; color figures only on
arxiv; revised to include references and minor proof change
Responses to supplementation by dairy cows given low pasture allowances in different seasons 2. Milk production
Two factorial experiments were designed to determine the effects of stage of lactation, and season of the year, on cow responses to supplementary feeding. These experiments were conducted over consecutive years with 128 high genetic merit multiparous Holstein-Friesian cows in early, mid and late lactation in spring, summer, autumn and winter. At each stage of lactation, and in each season of the year, cows were offered a restricted pasture allowance (25 to 35 kg dry matter (DM) per cow per day), either unsupplemented (control) or with supplement at 50 MJ metabolizable energy (ME) per cow per day in experiment 1 and 80 MJ ME per cow per day in experiment 2. The two supplements given in both years were rolled maize grain (MG) and a mixture of foods formulated to nutritionally balance the diet (BR). In experiment 2, another treatment, of a generous pasture allowance (60 to 75 kg DM per cow per day) (AP), was imposed on an additional group of early lactation cows during each season. Direct milk solids (MS) (milk fat plus milk protein) responses in experiment 1 to MG were 169, 279, 195 and 251 g MS per cow per day in spring, summer, autumn and winter, respectively, while those to BR were 107, 250, 192, 289 g MS per cow per day. In experiment 2, however, milk solids responses to both supplements during spring were slightly below the control treatment, with values similar to those in experiment 1 in summer and autumn for cows on the BR but not the MG supplement. Milk solids responses to supplementary foods were largest during seasons of the year when the quantity and quality of pasture on offer resulted in the lowest milk solids yield from unsupplemented cows. When carry-over effects of feeding MG and BR on milk solids production were detected, they were only about half the magnitude of the direct effects. Serum urea concentrations were higher in control cows than those offered MG with a similar effect for BR in all but summer in experiment 1, while serum glucose concentrations were highest in winter and lowest in summer. The most important factor influencing milk solids responses was the relative food deficit (RFD) represented by the decline in milk solids yield of the respective control groups after,changing from a generous pasture allowance to restricted allowance when the feeding treatments were imposed. Total milk solids responses (direct and carry-over) to supplements were greatest when severe food restrictions, relative to the cows' current food demand, resulted in large reductions in milk solids yield of the control groups. The RFD was the best predictor of milk solids response to supplementary foods. Therefore, it is likely that cows are most responsive to supplementary foods during or immediately after the imposition of a severe food restriction
Responses to supplementation by dairy cows given low pasture allowances in different seasons 1. Pasture intake and substitution
Two factorial experiments were designed to determine the effects of stage of lactation, and season of the year, on cow responses to supplementary feeding. These experiments were conducted over consecutive years with 128 high genetic merit multiparous Holstein-Friesian cows in early, mid and late lactation in spring, summer, autumn and winter. At each stage of lactation, and in each season of the year, cows were offered a restricted pasture allowance (25 to 35 kg dry matter (DM) per cow per day), either unsupplemented (control) or supplemented with 50 MJ metabolizable energy (ME) per cow per day in experiment 1 and 80 MJ ME per cow per day in experiment 2. Two different supplements were offered, namely, rolled maize grain (MG) and a mixture of foods (BR) formulated to nutritionally balance the diet. In experiment 2, a fourth treatment consisting solely of a generous pasture allowance (60 to 75 kg DM per cow per day, AP) was introduced. Offering MG and BR increased DM intake (DMI). At the restricted pasture allowance, increasing total ME allowance (MEA) by offering supplementary foods increased ME intake (MEI) by 0.68 (s.e. 0.047) MJ per extra MJ ME offered. This highly significant (P < 0.001) linear relationship was consistent across seasons, and did not diminish at higher MEA. In experiment 2, cows in early lactation had lower substitution rates than mid and late lactation cows irrespective of season. Substitution rate was higher when higher pasture allowance or quality of pasture on offer enabled the unsupplemented cows to achieve higher DMI from pasture than at other times of the year. These results suggest that one of the key factors determining the intake response to supplementary foods is pasture allowance. Within spring calving dairying systems, the largest increases in total DMI per kg of supplement offered is likely when offering supplements to early lactation cows grazing restricted allowances of high quality pasture
THE ROLE OF PRODUCT ATTRIBUTES IN THE AGRICULTURAL NEGOTIATIONS
Marketing, International Relations/Trade,
Maternal Characteristics Associated with Injury-related Infant Death in West Virginia, 2010-2014
Although injury-related deaths have been documented among children and adult populations, insufficient attention has been directed towards injury-related infant deaths. The objective of this retrospective study was to investigate maternal and infant characteristics associated with injury-related infant deaths in West Virginia. Birth and infant mortality data for 2010–2014 were sourced from the West Virginia Bureau for Public Health, Charleston. Relative risk was calculated using log-binomial regression utilizing generalized estimating equations. Maternal characteristics associated with injury-related infant mortality in West Virginia were race/ethnicity ( = 7.48, p = .03), and smoking during pregnancy (, p \u3c .00). Risk of a Black Non-Hispanic infant suffering an injury-related death was 4.0 (95% CL 1.7, 9.3) times that of infants of other races/ethnicities. Risk of an infant dying from an injury-related cause, if the mother smoked during pregnancy, was 2.9 (95% CL 1.6, 5.0) times the risk of such a death if maternal smoking status during pregnancy is unknown or no smoking, controlling for race/ethnicity. This study provides important information to public health stakeholders at both the state and local levels in designing interventions for partial reduction or prevention of injury-related infant mortality in West Virginia
Offsetting of CO₂ emissions by air capture in mine tailings at the Mount Keith Nickel Mine, Western Australia: Rates, controls and prospects for carbon neutral mining
The hydrated Mg-carbonate mineral, hydromagnesite [Mg₅(CO₃)₄(OH)₂•4H₂O], precipitates within mine tailings at the Mount Keith Nickel Mine, Western Australia as a direct result of mining operations. We have used quantitative mineralogical data and δ¹³C, δ¹⁸O and F¹⁴C isotopic data to quantify the amount of CO₂fixation and identify carbon sources. Our radiocarbon results indicate that at least 80% of carbon stored in hydromagnesite has been captured from the modern atmosphere. Stable isotopic results indicate that dissolution of atmospheric CO₂ into mine tailings water is kinetically limited, which suggests that the current rate of carbon mineralization could be accelerated. Reactive transport modeling is used to describe the observed variation in tailings mineralogy and to estimate rates of CO₂ fixation. Based on our assessment, approximately 39,800 t/yr of atmospheric CO₂ are being trapped and stored in tailings at Mount Keith. This represents an offsetting of approximately 11% of the mine's annual greenhouse gas emissions. Thus, passive sequestration via enhanced weathering of mineral waste can capture and store a significant amount of CO₂. Recommendations are made for changes to tailings management and ore processing practices that have potential to accelerate carbonation of tailings and further reduce or completely offset the net greenhouse gas emissions at Mount Keith and many other mines
Divergent evolution of protein conformational dynamics in dihydrofolate reductase.
Molecular evolution is driven by mutations, which may affect the fitness of an organism and are then subject to natural selection or genetic drift. Analysis of primary protein sequences and tertiary structures has yielded valuable insights into the evolution of protein function, but little is known about the evolution of functional mechanisms, protein dynamics and conformational plasticity essential for activity. We characterized the atomic-level motions across divergent members of the dihydrofolate reductase (DHFR) family. Despite structural similarity, Escherichia coli and human DHFRs use different dynamic mechanisms to perform the same function, and human DHFR cannot complement DHFR-deficient E. coli cells. Identification of the primary-sequence determinants of flexibility in DHFRs from several species allowed us to propose a likely scenario for the evolution of functionally important DHFR dynamics following a pattern of divergent evolution that is tuned by cellular environment
Two Phases of Supersymmetric Gluodynamics
We argue that supersymmetric gluodynamics has two phases with equivalent
infrared behavior, one of which is asymptotically free and another one is
superstrongly coupled in the ultraviolet domain.Comment: Plain LaTeX, 6 pages, 2 figures in a uuencoded file Final version
which appeared in Phys. Rev. Let.75;2085-2087,1995 Corrected references and
some Comments with no effect on conclusion
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