373 research outputs found
High-Sugar Alfalfa for Dairy Cows
Alfalfa proteins are extensively degraded during wilting, silage fermentation, and in the rumen. To efficiently use alfalfa non protein N, rumen microbes need a readily available energy source such as nonstructural carbohydrates (NSC); otherwise, surplus N in the form of rumen ammonia is converted into urea and excreted in the environment. Increasing the NSC concentration of alfalfa was thus the focus of our research program. Our objectives were to assess the impact of high NSC alfalfa on digestibility and microbial protein synthesis measured in vitro, and on ingestion, rumen metabolism, N use efficiency, and dairy cow performance. Increasing NSC concentration of alfalfa significantly enhanced in vitro dry matter (DM) digestibility and decreased NH3-N concentration in rumen fluid. An increase of 23 g/kg in alfalfa NSC concentration can improve forage DM intake (+5 %) and energy corrected milk production (+8 %). Feeding high-NSC alfalfa led to a higher rumen pH, suggesting that sugars do not cause rumen acidosis, and to a lower milk urea N (MUN) indicating an improvement in N utilization. Increasing NSC concentration of alfalfa is a low-cost tool to improve its utilisation in dairy rations and potentially mitigate the environmental footprint of milk production
Increased Sugar Concentration with PM-Cutting and Wide Swathing Improves Alfalfa Silage Fermentation
Extensive protein degradation during silage fermentation reduces the efficiency of N utilization by ruminants and excess N is excreted in the environment. Forage nonstructural carbohydrates (NSC) represent the main source of readily fermentable energy for lactic bacteria during silage fermentation. Increasing forage NSC concentration can enhance silage fermentation, lactic acid production, and the decline in pH with an overall reduction in the extent of protein degradation.
The NSC concentration increases during the day in alfalfa (Medicago sativa L.) to reach a maximum by the end of the afternoon. Under good wilting conditions, PM-cut alfalfa wilted in wide swaths had a greater NSC concentration than AM-cut alfalfa (Morin et al. 2012). Our objective was to study the effect of PM cutting and wide swathing on alfalfa silage quality attributes
Improving Forage Nonstructural Carbohydrates through Management and Breeding
Nonstructural carbohydrates (NSC) are an important source of readily fermentable energy available to rumen microbes. Limited concentrations of readily available energy in forages combined with fast and intensive protein degradation contribute to poor N use efficiency by dairy cows and other ruminants. Increasing NSC in forages has been shown to improve intake, milk yield, and N use efficiency (Brito et al. 2009). We assessed several strategies to increase forage NSC accumulation, including PM-cutting, species selection and genetic improvement
Experimental realization of the one qubit Deutsch-Jozsa algorithm in a quantum dot
We perform quantum interference experiments on a single self-assembled
semiconductor quantum dot. The presence or absence of a single exciton in the
dot provides a qubit that we control with femtosecond time resolution. We
combine a set of quantum operations to realize the single-qubit Deutsch-Jozsa
algorithm. The results show the feasibility of single qubit quantum logic in a
semiconductor quantum dot using ultrafast optical control.Comment: REVTex4, 4 pages, 3 figures. Now includes more details about the
dephasing in the quantum dots. The introduction has been reworded for
clarity. Minor readability fixe
Long term evaluation of disease progression through the quantitative magnetic resonance imaging of symptomatic knee osteoarthritis patients: correlation with clinical symptoms and radiographic changes
The objective of this study was to further explore the cartilage volume changes in knee osteoarthritis (OA) over time using quantitative magnetic resonance imaging (qMRI). These were correlated with demographic, clinical, and radiological data to better identify the disease risk features. We selected 107 patients from a large trial (n = 1,232) evaluating the effect of a bisphosphonate on OA knees. The MRI acquisitions of the knee were done at baseline, 12, and 24 months. Cartilage volume from the global, medial, and lateral compartments was quantified. The changes were contrasted with clinical data and other MRI anatomical features. Knee OA cartilage volume losses were statistically significant compared to baseline values: -3.7 ± 3.0% for global cartilage and -5.5 ± 4.3% for the medial compartment at 12 months, and -5.7 ± 4.4% and -8.3 ± 6.5%, respectively, at 24 months. Three different populations were identified according to cartilage volume loss: fast (n = 11; -13.2%), intermediate (n = 48; -7.2%), and slow (n = 48; -2.3%) progressors. The predictors of fast progressors were the presence of severe meniscal extrusion (p = 0.001), severe medial tear (p = 0.005), medial and/or lateral bone edema (p = 0.03), high body mass index (p < 0.05, fast versus slow), weight (p < 0.05, fast versus slow) and age (p < 0.05 fast versus slow). The loss of cartilage volume was also slightly associated with less knee pain. No association was found with other Western Ontario McMaster Osteoarthritis Index (WOMAC) scores, joint space width, or urine biomarker levels. Meniscal damage and bone edema are closely associated with more cartilage volume loss. These data confirm the significant advantage of qMRI for reliably measuring knee structural changes at as early as 12 months, and for identifying risk factors associated with OA progression
Mesoscopic superpositions of vibronic collective states of N trapped ions
We propose a scalable procedure to generate entangled superpositions of
motional coherent states and electronic states in N trapped ions. Beyond their
fundamental importance, these states may be of interest for quantum information
processing and may be used in experimental studies of decoherence.Comment: Final version, as published in Physical Review Letters. See also
further developments and applications in quant-ph/020207
The Road to Quantum Computational Supremacy
We present an idiosyncratic view of the race for quantum computational
supremacy. Google's approach and IBM challenge are examined. An unexpected
side-effect of the race is the significant progress in designing fast classical
algorithms. Quantum supremacy, if achieved, won't make classical computing
obsolete.Comment: 15 pages, 1 figur
Two-Bit Gates are Universal for Quantum Computation
A proof is given, which relies on the commutator algebra of the unitary Lie
groups, that quantum gates operating on just two bits at a time are sufficient
to construct a general quantum circuit. The best previous result had shown the
universality of three-bit gates, by analogy to the universality of the Toffoli
three-bit gate of classical reversible computing. Two-bit quantum gates may be
implemented by magnetic resonance operations applied to a pair of electronic or
nuclear spins. A ``gearbox quantum computer'' proposed here, based on the
principles of atomic force microscopy, would permit the operation of such
two-bit gates in a physical system with very long phase breaking (i.e., quantum
phase coherence) times. Simpler versions of the gearbox computer could be used
to do experiments on Einstein-Podolsky-Rosen states and related entangled
quantum states.Comment: 21 pages, REVTeX 3.0, two .ps figures available from author upon
reques
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