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Search Results: 1 - 10 of 53520 matches for " David Wise "
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Phenology and Life History of the Filmy Dome Spider (Araneae: Linyphiidae)in two Local Maryland Populations
David H. Wise
Psyche , 1984, DOI: 10.1155/1984/78276
Frequencies of Color Morphs in Four Populations of Enoplognatha Ovata (Araneae: Theridiidae) in Eastern North America
David H. Wise,Paul R. Reillo
Psyche , 1985, DOI: 10.1155/1985/45795
Couplings of a Light Dilaton and Violations of the Equivalence Principle
David B. Kaplan,Mark B. Wise
Physics , 2000, DOI: 10.1088/1126-6708/2000/08/037
Abstract: Experimental discovery of the dilaton would provide strong evidence for string theory. A light dilaton could show up in current tests of the inverse square law for gravity at sub-millimeter distances. In the large extra dimension scenario, Kaluza-Klein excitations of the dilaton can also contribute to the cooling of supernovae. In order to quantify these effects we compute the couplings of a low energy dilaton to matter. These predominantly arise from the fundamental dilaton coupling to the gluon field strength, which receives a sizable enhancement from QCD scaling. We show that detection of the dilaton will give a direct measurement of the QCD coupling constant at the string scale. Particular attention is paid to the size of equivalence principle violating dilaton couplings.
Emergency burr holes: "How to do it"
Mark H Wilson, David Wise, Gareth Davies, David Lockey
Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine , 2012, DOI: 10.1186/1757-7241-20-24
Abstract: No patients involvedThis paper describes a simple approach to emergency burr hole evacuation of extra-axial intracranial haematoma that can be used in the uncommon situation when life saving specialist neurosurgical intervention is not available.Rapidly expanding intracranial haematomas associated with fixed dilated pupils are rapidly fatal. A recently fixed dilated pupil with corresponding imaging evidence of an extra-axial haematoma is considered an indication for emergency targeted burr hole placement.Extra-axial haematomas (extradural/subdural) by definition are outside the brain and hence are not a primary brain injury. It is the delay in removing the compression of the brain by the clot that causes brain injury and death.Ideal treatment is provided by immediate specialist neurosurgical care. However in many parts of the world, this is not always available and the risks of delay associated with secondary transfer have to be balanced with the risks of the procedure being done by a non-specialist. At one UK neurosurgical centre, the median transfer time was 5.25 hours for patients with extradural haematoma and 6 hours for subdural haematoma [1]. The prolonged transfer of a patient with fixed/dilated pupils is unlikely to have a good outcome. Transfer of this type of patient is analogous to transferring a patient with other time critical but reversible pathology such as a tension pneumothorax. There are many reports of non-specialists successfully performing emergency burr holes [2]. These are often done with household drills and other makeshift tools which, when successful, has created media interest [3]. Although there have been significant technical advances in the safety of the procedure since the time of "exploratory" burr holes, there has simultaneously been a reduction in the number of surgeons either having experience in or being willing to perform the procedure. A number of general surgeons working in remote areas of Australia are more confident in perfor
A Perturbative Calculation of the Electromagnetic Form Factors of the Deuteron
David B. Kaplan,Martin J. Savage,Mark B. Wise
Physics , 1998, DOI: 10.1103/PhysRevC.59.617
Abstract: Making use of the effective field theory expansion recently developed by the authors, we compute the electromagnetic form factors of the deuteron analytically to next-to-leading order (NLO). The computation is rather simple, and involves calculating several Feynman diagrams, using dimensional regularization. The results agree well with data and indicate that the expansion is converging. They do not suffer from any ambiguities arising from off-shell versus on-shell amplitudes.
Nucleon-Nucleon Scattering from Effective Field Theory
David B. Kaplan,Martin J. Savage,Mark B. Wise
Physics , 1996, DOI: 10.1016/0550-3213(96)00357-4
Abstract: We perform a nonperturbative calculation of the 1S0 NN scattering amplitude using an effective field theory (EFT) expansion. The expansion we advocate is a modification of what has been used previously; it is no a chiral expansion in powers of the pion mass. We use dimensional regularization throughout and the MS-bar subtraction scheme; our final result depends only on physical observables. We show that the EFT expansion of the quantity |p|cot delta(p) converges at momenta much greater than the scale that characterizes the derivative expansion of the EFT Lagrangian. Our conclusions are optimistic about the applicability of an EFT approach to the quantitative study of nuclear matter.
On the contribution of active galactic nuclei to reionization (Research Note)
Rachel L. Grissom,David R. Ballantyne,John H. Wise
Physics , 2013, DOI: 10.1051/0004-6361/201322637
Abstract: The electron scattering optical depth constraints on reionization suggest that there may be other sources that contribute to the ionization of hydrogen aside from observable star forming galaxies. Often the calculated value of the electron scattering optical depth, \tau_{es}, falls below the measurements derived from observations of the CMB or an assumption about non-observable sources must be made in order to reach agreement. Here, we calculate the hydrogen ionization fraction as a function of redshift and the electron scattering optical depth from both galaxies and active galactic nuclei (AGN) factoring in the secondary collisional ionizations from the AGN X-ray emission. In this paper we use the most current determination of the evolving hard X-ray luminosity function and extrapolate its evolution beyond z = 6. The AGN spectral energy distributions (SEDs) include both UV and X-ray ionizing photons. To search for the largest possible effect, all AGN are assumed to have \lambda_{Edd} = 1.0 and be completely unobscured. The results show that AGNs produce a perturbative effect on the reionization of hydrogen and remains in agreement with current constraints. Our calculations find the epoch of reionization still ends at z \approx 6 and only increases the electron scattering optical depth by ~2.3% under the most optimal conditions. This can only be moderately increased by assuming a constant black hole mass of M_{BH} = 10^(5) solar masses. As a result, we conclude that there is a need for other sources beyond observable galaxies and AGNs that contribute to the reionization of hydrogen at z > 6.
A New Expansion for Nucleon-Nucleon Interactions
David B. Kaplan,Martin J. Savage,Mark B. Wise
Physics , 1998, DOI: 10.1016/S0370-2693(98)00210-X
Abstract: We introduce a new and well defined power counting for the effective field theory describing nucleon-nucleon interactions. Because of the large NN scattering lengths it differs from other applications of chiral perturbation theory and is facilitated by introducing an unusual subtraction scheme and renormalization group analysis. Calculation to subleading order in the expansion can be done analytically, and we present the results for both the 1S0 and 3S1-3D1 channels.
Two-Nucleon Systems from Effective Field Theory
David B. Kaplan,Martin J. Savage,Mark B. Wise
Physics , 1998, DOI: 10.1016/S0550-3213(98)00440-4
Abstract: We elaborate on a new technique for computing properties of nucleon-nucleon interactions in terms of an effective field theory derived from low energy NN scattering data. Details of how the expansion is carried out to higher orders are presented. Analytic formulae are given for the amplitude to subleading order in both the 1S0 and 3S1-3D1 channels.
Macrolides and community-acquired pneumonia: is quorum sensing the key?
Matt P Wise, David W Williams, Michael AO Lewis, Paul J Frost
Critical Care , 2010, DOI: 10.1186/cc9084
Abstract: Outcome in community-acquired pneumonia (CAP) is adversely affected by increasing severity of illness, comorbidity and age. Organisational factors such as timely administration of appropriate antibiotics, prompt admission to critical care and adherence to antibiotic policies, however, are also important in influencing outcome [1-3]. Combination therapy with two antimicrobial agents seems superior to monotherapy in severe CAP, and this approach is recommended by a number of organisations [4,5]. The Infectious Diseases Society of America/American Thoracic Society guidelines suggest therapy with a β-lactam antibiotic, with the addition of either a macrolide or fluoroquinolone antibiotic [4], whilst the British Thoracic Society recommends initiating a β-lactam/macrolide antibiotic combination [5].Martin-Loeches and colleagues recently conducted a prospective, observational cohort, multicentre study involving 218 mechanically ventilated CAP patients to see what effect different antibiotic combinations had on mortality [6]. These investigators reported that the addition of a macrolide, but not a fluoroquinolone, to standard antibiotic therapy was associated with reduced mortality in patients admitted to critical care with CAP. Death in critical care occurred in 26.1% of individuals receiving combination therapy with a macrolide, compared with 46.3% in those receiving fluoroquinolones [6]. These results support data from other observational studies that suggest β-lactam/macrolide combinations offer a survival advantage in severe CAP. This body of data is not scientifically robust enough, however, to adequately answer the question of whether adding a macrolide to a β-lactam confers a survival advantage - this will only be satisfactorily addressed by a large prospective randomised control trial.In addition to activity against atypical bacteria, macrolides have ubiquitous immunomodulatory effects. Speculating how this group of drugs might offer a survival advantage when added
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