961 research outputs found
In Vitro Culture and Non-Surgical Transfer of Micromanipulated Bovine Embryos.
A total of 374 non-surgically recovered bovine embryos (EMB) was used to evaluate in vitro culture systems for micromanipulated (MICRO) EMB and to assess EMB development following various MICRO procedures. In Experiment I, viability at 12, 24, 36, 48, 60 and 72 h of culture of 39 demi-embryos (DE) in Ham\u27s F-10 with 10% FCS (HF-10) was 43, 41, 33, 28, 21 and 18% compared with 69, 69, 69, 67, 62 and 62% for DE cocultured with bovine uterine fibroblasts (BUF) in HF-10. These results demonstrate the BUF coculture system\u27s superiority to HF-10 for culturing bovine DE. Experiment II was conducted to assess quartering blastocyst stage EMB. In Trt (A) 15 EMB were MICRO into quarter embryos (QE). IN Trt (B) 15 EMB were bisected into DE, cultured for 2 to 4 h and split into QE. Intact EMB (IE) in Trt (C) served as non-MICRO controls. Fifty-four QE produced in Trt (A) and 34 QE produced in Trt (B) were cocultured with BUF in HF-10 as were IE in Trt (C). Eight QE (14.8%) in Trt (A) and 6 QE (17.6%) in Trt (B) re-expanded into blastocysts while 10 (66.6%) of the IE in Trt (C) were viable in culture. These data suggest that blastocyst stage EMB cannot be split into viable QE using this technique. The effect of puncturing the zona pellucida (ZP) on in vitro blastocyst hatching was evaluated in Experiment III. Seventy-five blastocysts were equally allotted across three Trt. Using MICRO techniques the ZP of EMB were punctured at the ICM (Trt A) or apex of trophoblast (Trt B) while EMB in Trt (C) were non-MICRO controls. All EMB were cocultured with BUF cells in HF-10. Time at which hatching was initiated and size of hatched blastocysts were similar across Trts. EMB in Trt (A) and (B) completed hatching earlier (P \u3c .05) than control EMB (48.9 (+OR-) 5.8, 43.5 (+OR-) 4.4 and 61.1 (+OR-) 4.8 h, respectively). One EMB in Trt (A) and (B) split into half EMB via hatching through the ZP puncture. In Experiment VI, pregnancy rates for non-surgically transferred IE (n = 91) and DE (n = 123) were 46.2% and 37.4%, respectively. Pregnancy rates for DE transferred with and without a ZP were 39.7% and 34.0%, respectively. MICRO of EMB can be conducted while maintaining acceptable pregnancy rates and replacing DE in a ZP is not a prerequisite for successful non-surgical transfer
Psychiatric Factors Which Impact Coronary Heart Disease and Influence Outcomes Post-Coronary Artery Bypass Grafting Surgery
Paper Session III-B - Risk Management for Small Satellite Programs
During an era of shrinking federal budgets, the Space Test Program has developed a management philosophy for accepting greater risks in managing small satellite programs for technology demonstration. This innovative philosophy complies with the latest government initiatives to reduce cost by using contractors’ best practices, eliminating use of government specifications and standards, and minimizing the size of the program office. We achieve program cost goals by matching the contract type to the perceived program risk, reducing program documentation, using non-redundant subsystems where possible, relaxing test requirements, and using minimal staff during on-orbit operations. However, we mitigate these increased risks and successfully perform our mission by developing detailed payload requirements early in the program, building system redundancy in appropriate areas, and applying vigorous attention to the spacecraft interfaces to the payload, the launch vehicle, and the mission control center. While these practices may not be appropriate for all satellite programs, we feel they apply to a broad range of research and technology demonstration spacecraft
Leukotriene E4 elimination and metabolism in normal human subjects
Radiolabeled leukotriene (LT) E4 was infused into three healthy subjects in order to assess the production and elimination of sulfidopeptide leukotriene metabolites in urine. Three different radiolabeled tracers were employed, [14,15-3H]LTE4, [35S]LTE4, and [14C] LTE4 in five separate infusion studies. There was a rapid disappearance of radioactivity from the vascular compartment in an apparent two-phase process. The first elimination phase had an apparent half-life of approximately 7 min. Radioactivity quickly appeared in the urine with 10-16% eliminated during the first 2 h following intravenous infusion; 7%, 2-5 h; 4%, 5-8 h; 4%, 8-15 h; and 1.5%, 15-24 h from the [14C] LTE4 experiments. Unmetabolized LTE4 was the major radioactive component in the first urine collection, but at later times two more polar compounds predominated. After extensive purification by normal phase-solid phase extraction and reverse-phase high performance liquid chromatography, these compounds were characterized by UV spectroscopy, co-elution with synthetic standards, negative ion electron capture gas chromatography/mass spectrometry, and tandem mass spectrometry. The two major urinary metabolites were structurally determined to be 14-carboxy-hexanor-LTE3 and the conjugated tetraene, 16-carboxy-\u39413-tetranor-LTE4. Three other minor metabolites were detectable in the first urine collection only and were characterized by co-elution with synthetic standards as 16-carboxy-tetranor-LTE3, 18-carboxy-dinor-LTE4, and 20-carboxy-LTE4. \u3c9-Oxidation and subsequent \u3b2-oxidation from the methyl terminus appeared to be the major metabolic fate for sulfidopeptide leukotrienes in man. The accumulation of the 14-COOH-LTE3 and 16-COOH-\u39413-LTE4 may reflect a rate-limiting step in further oxidation of these compounds which places a conjugated triene or conjugated tetraene, respectively, two carbons removed from the CoA ester moiety. Also in the first urine collection there was another minor metabolite identified as N-acetyl-LTE4, however, no subsequent \u3b2-oxidation of this metabolite was observed. The major metabolites of LTE4 might be useful in assessing in vivo production of sulfidopeptide leukotrienes in humans
Soliton pair dynamics in patterned ferromagnetic ellipses
Confinement alters the energy landscape of nanoscale magnets, leading to the
appearance of unusual magnetic states, such as vortices, for example. Many
basic questions concerning dynamical and interaction effects remain unanswered,
and nanomagnets are convenient model systems for studying these fundamental
physical phenomena. A single vortex in restricted geometry, also known as a
non-localized soliton, possesses a characteristic translational excitation mode
that corresponds to spiral-like motion of the vortex core around its
equilibrium position. Here, we investigate, by a microwave reflection
technique, the dynamics of magnetic soliton pairs confined in lithographically
defined, ferromagnetic Permalloy ellipses. Through a comparison with
micromagnetic simulations, the observed strong resonances in the subgigahertz
frequency range can be assigned to the translational modes of vortex pairs with
parallel or antiparallel core polarizations. Vortex polarizations play a
negligible role in the static interaction between two vortices, but their
effect dominates the dynamics.Comment: supplemental movies on
http://www.nature.com/nphys/journal/v1/n3/suppinfo/nphys173_S1.htm
An aggregation-based approximate dynamic programming approach for the periodic review model with random yield
A manufacturer places orders periodically for products that are shipped from a supplier. During transit, orders get damaged with some probability, that is, the order is subject to random yield. The manufacturer has the option to track orders to receive information on damages and to potentially place additional orders. Without tracking, the manufacturer identifies potential damages after the order has arrived. With tracking, the manufacturer is informed about the damage when it occurs and can respond to this information. We model the problem as a dynamic program with stochastic demand, tracking cost, and random yield. For small problem sizes, we provide an adjusted value iteration algorithm that finds the optimal solution. For moderate problem sizes, we propose a novel aggregation-based approximate dynamic programming (ADP) algorithm and provide solutions for instances for which it is not possible to obtain optimal solutions. For large problem sizes, we develop a heuristic that takes tracking costs into account. In a computational study, we analyze the performance of our approaches. We observe that our ADP algorithm achieves savings of up to 16% compared to existing heuristics. Our heuristic outperforms existing ones by up to 8.1%. We show that dynamic tracking reduces costs compared to tracking always or never and identify savings of up to 3.2%
CXCR4 Inhibition Ameliorates Severe Obliterative Pulmonary Hypertension and Accumulation of C-Kit+ Cells in Rats
Successful curative treatment of severe pulmonary arterial hypertension with luminal obliteration will require a thorough understanding of the mechanism underlying the development and progression of pulmonary vascular lesions. But the cells that obliterate the pulmonary arterial lumen in severe pulmonary arterial hypertension are incompletely characterized. The goal of our study was to evaluate whether inhibition of CXC chemokine receptor 4 will prevent the accumulation of c-kit+ cells and severe pulmonary arterial hypertension. We detected c-kit+ cells expressing endothelial (von Willebrand Factor) or smooth muscle cell/myofibroblast (α-smooth muscle actin) markers in pulmonary arterial lesions of SU5416/chronic hypoxia rats. We found increased expression of CXC chemokine ligand 12 in the lung tissue of SU5416/chronic hypoxia rats. In our prevention study, AMD3100, an inhibitor of the CXC chemokine ligand 12 receptor, CXC chemokine receptor 4, only moderately decreased pulmonary arterial obliteration and pulmonary hypertension in SU5416/chronic hypoxia animals. AMD3100 treatment reduced the number of proliferating c-kit+ α-smooth muscle actin+ cells and pulmonary arterial muscularization and did not affect c-kit+ von Willebrand Factor+ cell numbers. Both c-kit+ cell types expressed CXC chemokine receptor 4. In conclusion, our data demonstrate that in the SU5416/chronic hypoxia model of severe pulmonary hypertension, the CXC chemokine receptor 4-expressing c-kit+ α-smooth muscle actin+ cells contribute to pulmonary arterial muscularization. In contrast, vascular lumen obliteration by c-kit+ von Willebrand Factor+ cells is largely independent of CXC chemokine receptor 4
Enhanced Out-of-plane Emission of K+ Mesons observed in Au+Au Collisions at 1 AGeV
The azimuthal angular distribution of K+ mesons has been measured in Au + Au
collisions at 1 AGeV. In peripheral and semi-central collisions, K+ mesons
preferentially are emitted perpendicular to the reaction plane. The strength of
the azimuthal anisotropy of K+ emission is comparable to the one of pions. No
in-plane flow was found for K+ mesons near projectile and target rapidity.Comment: Accepted for publication in Phys. Rev.Let
Noise-induced switching between vortex states with different polarization in classical two-dimensional easy-plane magnets
In the 2-dimensional anisotropic Heisenberg model with XY-symmetry there are
non-planar vortices which exhibit a localized structure of the z-components of
the spins around the vortex center. We study how thermal noise induces a
transition of this structure from one polarization to the opposite one. We
describe the vortex core by a discrete Hamiltonian and consider a stationary
solution of the Fokker-Planck equation. We find a bimodal distribution function
and calculate the transition rate using Langer's instanton theory (1969). The
result is compared with Langevin dynamics simulations for the full many-spin
model.Comment: 15 pages, 4 figures, Phys. Rev. B., in pres
Handbook for Aboriginal Alcohol and Drug Work
The Handbook for Aboriginal Alcohol and Drug Work is a practical tool written for Aboriginal drug and alcohol workers, mental health workers and others working in this field. It offers a detailed look at alcohol and drug work from clinical, through to prevention, early intervention and harm reduction. This handbook is also likely to help people working to improve policy and those advocating for change. The idea for it came from workers all over Australia. They told us that they needed an easy to use handbook that can help them respond to the range of alcohol and drug issues they face every day. They also told us that such a book needs to take into account the complex challenges facing workers when helping clients, their families and, sometimes, whole communities
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