5,525 research outputs found
k_T factorization is violated in production of high-transverse-momentum particles in hadron-hadron collisions
We show that hard-scattering factorization is violated in the production of
high-p_T hadrons in hadron-hadron collisions, in the case that the hadrons are
back-to-back, so that k_T factorization is to be used. The explicit
counterexample that we construct is for the single-spin asymmetry with one beam
transversely polarized. The Sivers function needed here has particular
sensitivity to the Wilson lines in the parton densities. We use a greatly
simplified model theory to make the breakdown of factorization easy to check
explicitly. But the counterexample implies that standard arguments for
factorization fail not just for the single-spin asymmetry but for the
unpolarized cross section for back-to-back hadron production in QCD in
hadron-hadron collisions. This is unlike corresponding cases in e^+e^-
annihilation, Drell-Yan, and deeply inelastic scattering. Moreover, the result
endangers factorization for more general hadroproduction processes.Comment: 10 pages. V. 2: Title change, misprints and minor corrections, as in
journal versio
Judging Biden
It would have been easy for President Joe Biden to approach judicial appointments (and, particularly, circuit court appointments) the same way as the Administration he served as Vice President. Like President Obama, President Biden inherited a country in turmoil. A deadly pandemic had killed nearly 400,000 Americans. Necessary quarantine orders shuttered schools and businesses, and ground the economy to a halt. Partisan tensions were still raging, culminating in the violent storming of the Capitol by right-wing insurrectionists. People needed the vaccine, economic relief, and a return to some semblance of normalcy. Also, like President Obama (and thanks to President Trump), President Biden inherited relatively few judicial vacancies—only forty-six, the fewest since President George H.W. Bush inherited thirty-seven in 1989. So, like President Obama, you could understand if President Biden felt the need to focus his efforts elsewhere. But after watching President Trump appoint young, deeply conservative appellate judges and justices for four years, the Biden Administration realized it could not repeat the same well-meaning mistakes Democratic administrations had been making for decades. Instead, it has recognized that—at least for the time being—it has an opportunity to make an impact on the federal judiciary and seems poised to do what it can to maximize it
Antimicrobial stewardship practices in Virginia
The Society of Healthcare Epidemiology of America, the Centers for Disease Control and Prevention, and the President\u27s Council of Advisors on Science and Technology recognize the need to combat antimicrobial resistance through the promotion of antimicrobial stewardship programs. Health care facilities in Virginia were surveyed using a 23-item survey focused on facility characteristics and antimicrobial stewardship strategies. Antimicrobial stewardship activities were highly variable and many are missing key personnel and resources
N-Cadherin cleavage during activated hepatic stellate cell apoptosis is inhibited by tissue inhibitor of metalloproteinase-1. [In supplement: 11th International Symposium on the Cells of the Hepatic Sinusoid and their Relation to Other Cells]
Apoptosis of hepatic stellate cells (HSC) has previously been shown to occur during spontaneous resolution of experimental liver fibrosis. TIMP-1 has also been shown to have a key role because of its ability to inhibit apoptosis of HSC via matrix metalloproteinase (MMP) inhibition. This has led to further study of novel substrates for MMPs that might impact on HSC survival. N-Cadherin is known to mediate cell-cell contacts in fibroblasts. In this study we demonstrate that N-Cadherin is expressed by activated rat HSC. Furthermore, during apoptosis of HSC, the N-Cadherin is cleaved into smaller fragments. Apoptosis of HSC may be inhibited by TIMP-1. This is associated with reduced fragmentation of N-Cadherin. N-Cadherin may have an important role in supporting HSC survival while N-Cadherin cleavage may play a part in promoting HSC apoptosis in recovery from liver fibrosis
Evaporative CO2 cooling using microchannels etched in silicon for the future LHCb vertex detector
The extreme radiation dose received by vertex detectors at the Large Hadron
Collider dictates stringent requirements on their cooling systems. To be robust
against radiation damage, sensors should be maintained below -20 degree C and
at the same time, the considerable heat load generated in the readout chips and
the sensors must be removed. Evaporative CO2 cooling using microchannels etched
in a silicon plane in thermal contact with the readout chips is an attractive
option. In this paper, we present the first results of microchannel prototypes
with circulating, two-phase CO2 and compare them to simulations. We also
discuss a practical design of upgraded VELO detector for the LHCb experiment
employing this approach.Comment: 12 page
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