2,909 research outputs found

    The eccentricity in heavy-ion collisions from Color Glass Condensate initial conditions

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    The eccentricity in coordinate-space at midrapidity of the overlap zone in high-energy heavy-ion collisions predicted by the kk_\perp-factorization formalism is generically larger than expected from scaling with the number of participants. We provide a simple qualitative explanation of the effect which shows that it is not caused predominantly by edge effects. We also show that it is quite insensitive to ``details'' of the unintegrated gluon distribution functions such as the presence of leading-twist shadowing and of an extended geometric scaling window. The larger eccentricity increases the azimuthal asymmetry of high transverse momentum particles. Finally, we point out that the longitudinal structure of the Color Glass Condensate initial condition for hydrodynamics away from midrapidity is non-trivial but requires understanding of large-xx effects.Comment: 8 pages, 7 figures; v3: added note regarding Qs2~n_part versus Qs2~T_A, final version to appear in PR

    Examining the relationship between chain governance structures and chain performance : an empirical evidence of the dairy sector

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    Purpose: The purpose of this paper is to analyze the influence of chain governance on chain performance among the chain members. Design/methodology/approach: The survey was conducted in a triadic context with 345 chain members (115 dairy farmers, 115 dairy cooperative managers, and 115 processors) of the dairy sector in Uganda. Data collection was performed through simple random sampling by survey questionnaires with the chain executives. SEM was used for data analysis. Findings: The results revealed several chain governance structures (spot market, relational, contractual and mini integration) confirmed the hypothesized correlations on chain performance at different chain levels. The authors found a positive influence of relational governance on chain performance for all the chain members; however, the effect is stronger at the first supplier chain level. Originality/value: This triadic chain approach makes an original contribution to the chain governance structures and chain performance literature in the supply chain context. Studies analyzing all aspects of chain governance structure and chain performance at three chain levels are limited

    Advanced hypersonic aircraft design

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    The objective of this design project is to develop the hypersonic reconnaissance aircraft to replace the SR-71 and to complement existing intelligence gathering devices. The initial design considerations were to create a manned vehicle which could complete its mission with at least two airborne refuelings. The aircraft must travel between Mach 4 and Mach 7 at an altitude of 80,000 feet for a maximum range of 12,000 nautical miles. The vehicle should have an air breathing propulsion system at cruise. With a crew of two, the aircraft should be able to take off and land on a 10,000 foot runway, and the yearly operational costs were not to exceed $300 million. Finally, the aircraft should exhibit stealth characteristics, including a minimized radar cross-section (RCS) and a reduced sonic boom. The technology used in this vehicle should allow for production between the years 1993 and 1995

    MDM2 prevents spontaneous tubular epithelial cell death and acute kidney injury

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    Murine double minute-2 (MDM2) is an E3-ubiquitin ligase and the main negative regulator of tumor suppressor gene p53. MDM2 has also a non-redundant function as a modulator of NF-kB signaling. As such it promotes proliferation and inflammation. MDM2 is highly expressed in the unchallenged tubular epithelial cells and we hypothesized that MDM2 is necessary for their survival and homeostasis. MDM2 knockdown by siRNA or by genetic depletion resulted in demise of tubular cells in vitro. This phenotype was completely rescued by concomitant knockdown of p53, thus suggesting p53 dependency. In vivo experiments in the zebrafish model demonstrated that the tubulus cells of the larvae undergo cell death after the knockdown of mdm2. Doxycycline-induced deletion of MDM2 in tubular cell-specific MDM2-knockout mice Pax8rtTa-cre; MDM2f/f caused acute kidney injury with increased plasma creatinine and blood urea nitrogen and sharp decline of glomerular filtration rate. Histological analysis showed massive swelling of renal tubular cells and later their loss and extensive tubular dilation, markedly in proximal tubules. Ultrastructural changes of tubular epithelial cells included swelling of the cytoplasm and mitochondria with the loss of cristae and their transformation in the vacuoles. The pathological phenotype of the tubular cell-specific MDM2-knockout mouse model was completely rescued by co-deletion of p53. Tubular epithelium compensates only partially for the cell loss caused by MDM2 depletion by proliferation of surviving tubular cells, with incomplete MDM2 deletion, but rather mesenchymal healing occurs. We conclude that MDM2 is a non-redundant survival factor for proximal tubular cells by protecting them from spontaneous p53 overexpression-related cell death

    Topography of inland deltas: Observations, modeling, and experiments

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    The topography of inland deltas is influenced by the water-sediment balance in distributary channels and local evaporation and seepage rates. In this letter a reduced complexity model is applied to simulate inland delta formation, and results are compared with the Okavango Delta, Botswana and with a laboratory experiment. We show that water loss in inland deltas produces fundamentally different dynamics of water and sediment transport than coastal deltas, especially deposition associated with expansion-contraction dynamics at the channel head. These dynamics lead to a systematic decrease in the mean topographic slope of the inland delta with distance from the apex following a power law with exponent alpha = -0.69 +/- 0.02 where the data for both simulation and experiment can be collapsed onto a single curve. In coastal deltas, on the contrary, the slope increases toward the end of the deposition zone.This work was funded by the Swiss National Foundation grant NF20021-116050/1. The author D. A. was affiliated to the Institute of Geodesy and Photogrammetry of ETH Zurich when performing the project. J. S. A. J would like to thank the Brazilian agencies CNPq, CAPES and FUNCAP for financial support.Publisher's Versio

    Complex pleural empyema can be safely treated with vacuum-assisted closure

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    <p>Abstract</p> <p>Objective</p> <p>For patients with postoperative pleural empyema, open window thoracostomy (OWT) is often necessary to prevent sepsis. Vacuum-assisted closure (VAC) is a well-known therapeutic option in wound treatment. The efficacy and safety of intrathoracal VAC therapy, especially in patients with pleural empyema with bronchial stump insufficiency or remain lung, has not yet been investigated.</p> <p>Methods</p> <p>Between October 2009 and July 2010, eight consecutive patients (mean age of 66.1 years) with multimorbidity received an OWT with VAC for the treatment of postoperative or recurrent pleural empyema. Two of them had a bronchial stump insufficiency (BPF).</p> <p>Results</p> <p>VAC therapy ensured local control of the empyema and control of sepsis. The continuous suction up to 125 mm Hg cleaned the wound and thoracic cavity and supported the rapid healing. Additionally, installation of a stable vacuum was possible in the two patients with BPF. The smaller bronchus stump fistula closed spontaneously due to the VAC therapy, but the larger remained open.</p> <p>The direct contact of the VAC sponge did not create any air leak or bleeding from the lung or the mediastinal structures. The VAC therapy allowed a better re-expansion of remaining lung.</p> <p>One patient died in the late postoperative period (day 47 p.o.) of multiorgan failure. In three cases, VAC therapy was continued in an outpatient service, and in four patients, the OWT was treated with conventional wound care. After a mean time of three months, the chest wall was closed in five of seven cases. However, two patients rejected the closure of the OWT. After a follow-up at 7.7 months, neither recurrent pleural empyema nor BPF was observed.</p> <p>Conclusion</p> <p>VAC therapy was effective and safe in the treatment of complicated pleural empyema. The presence of smaller bronchial stump fistula and of residual lung tissue are not a contraindication for VAC therapy.</p

    On the Perils of Stabilizing Prices When Agents are Learning.

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    We show that price level stabilization is not optimal in an economy where agents have incomplete knowledge about the policy implemented and try to learn it. A systematically more accommodative policy than what agents expect generates short term gains without triggering an abrupt loss of con- fidence, since agents update expectations sluggishly. In the long run agents learn the policy implemented, and the economy converges to a rational expectations equilibrium in which policy does not stabilize prices, economic volatility is high, and agents suffer the corresponding welfare losses. However, these losses are outweighed by short term gains from the learning phase

    The network of photodetectors and diode lasers of the CMS Link alignment system

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    The central feature of the CMS Link alignment system is a network of Amorphous Silicon Position Detectors distributed throughout the muon spectrometer that are connected by multiple laser lines. The data collected during the years from 2008 to 2015 is presented confirming an outstanding performance of the photo sensors during more than seven years of operation. Details of the photo sensor readout of the laser signals are presented. The mechanical motions of the CMS detector are monitored using these photosensors and good agreement with distance sensors is obtained
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