2,490 research outputs found
Quasiclassical Limit in q-Deformed Systems, Noncommutativity and the q-Path Integral
Different analogs of quasiclassical limit for a q-oscillator which result in
different (commutative and non-commutative) algebras of ``classical''
observables are derived. In particular, this gives the q-deformed Poisson
brackets in terms of variables on the quantum planes. We consider the
Hamiltonian made of special combination of operators (the analog of even
operators in Grassmann algebra) and discuss q-path integrals constructed with
the help of contracted ``classical'' algebras.Comment: 19 pages, Late
Recommended from our members
A world allergy organization international survey on diagnostic procedures and therapies in drug allergy/hypersensitivity.
RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are.OBJECTIVE: To study the diagnostic and treatment modalities used in drug allergy/hypersensitivity among members of the World Allergy Organization (WAO). METHODS: A questionnaire comprising 39 questions was circulated electronically to member societies, associate member societies, and regional and affiliate organizations of WAO between June 29, 2009, and August 9, 2009. RESULTS: Eighty-two responses were received. Skin testing was used by 74.7%, with only 71.4% having access to penicillin skin test reagents. In vitro-specific IgE tests were used by 67.4%, and basophil activation test was used by 54.4%. Lymphocyte transformation tests were used by 36.8% and patch tests by 54.7%. Drug provocation tests were used by 68.4%, the most common indication being to exclude hypersensitivity where history/symptoms were not suggestive of drug hypersensitivity/allergy (76.9%). Rapid desensitization for chemotherapy, antibiotics, or biologic agents was used by 69.6%. Systemic corticosteroid was used in the treatment of Stevens-Johnson syndrome by 72.3%, and high-dose intravenous immunoglobulins in toxic epidermal necrolysis by 50.8%. Human leukocyte antigen screening before prescription of abacavir was used by 92.9% and before prescription of carbamazepine by 21.4%. CONCLUSIONS: Results of this survey form a useful framework for developing educational and training needs and for improving access to drug allergy diagnostic and treatment modalities across WAO member societies
A World Allergy Organization International Survey on Diagnostic Procedures and Therapies in Drug Allergy/Hypersensitivity
OBJECTIVE: To study the diagnostic and treatment modalities used in drug allergy/hypersensitivity among members of the World Allergy Organization (WAO). METHODS: A questionnaire comprising 39 questions was circulated electronically to member societies, associate member societies, and regional and affiliate organizations of WAO between June 29, 2009, and August 9, 2009. RESULTS: Eighty-two responses were received. Skin testing was used by 74.7%, with only 71.4% having access to penicillin skin test reagents. In vitro–specific IgE tests were used by 67.4%, and basophil activation test was used by 54.4%. Lymphocyte transformation tests were used by 36.8% and patch tests by 54.7%. Drug provocation tests were used by 68.4%, the most common indication being to exclude hypersensitivity where history/symptoms were not suggestive of drug hypersensitivity/allergy (76.9%). Rapid desensitization for chemotherapy, antibiotics, or biologic agents was used by 69.6%. Systemic corticosteroid was used in the treatment of Stevens–Johnson syndrome by 72.3%, and high-dose intravenous immunoglobulins in toxic epidermal necrolysis by 50.8%. Human leukocyte antigen screening before prescription of abacavir was used by 92.9% and before prescription of carbamazepine by 21.4%. CONCLUSIONS: Results of this survey form a useful framework for developing educational and training needs and for improving access to drug allergy diagnostic and treatment modalities across WAO member societies
Events in a Non-Commutative Space-Time
We treat the events determined by a quantum physical state in a
noncommutative space-time, generalizing the analogous treatment in the usual
Minkowski space-time based on positive-operator-valued measures (POVMs). We
consider in detail the model proposed by Snyder in 1947 and calculate the POVMs
defined on the real line that describe the measurement of a single coordinate.
The approximate joint measurement of all the four space-time coordinates is
described in terms of a generalized Wigner function (GWF). We derive lower
bounds for the dispersion of the coordinate observables and discuss the
covariance of the model under the Poincare' group. The unusual transformation
law of the coordinates under space-time translations is interpreted as a
failure of the absolute character of the concept of space-time coincidence. The
model shows that a minimal length is compatible with Lorents covariance.Comment: 13 pages, revtex. Introductory part shortened and some arguments made
more clea
Effective interactions and operators in no-core shell model
Solutions to the nuclear many-body problem rely on effective interactions,
and in general effective operators, to take into account effects not included
in calculations. These include effects due to the truncation to finite model
spaces where a numerical calculation is tractable, as well as physical terms
not included in the description in the first place. In the no-core shell model
(NCSM) framework, we discuss two approaches to the effective interactions based
on (i) unitary transformations and (ii) effective field theory (EFT)
principles. Starting from a given Hamiltonian, the unitary transformation
approach is designed to take into account effects induced by the truncation to
finite model spaces in which a numerical calculation is performed. This
approach was widely applied to the description of nuclear properties of light
nuclei; we review the theory and present representative results. In the EFT
approach, a Hamiltonian is always constructed in a truncated model space
according to the symmetries of the underlying theory, making use of power
counting to limit the number of interactions included in the calculations.
Hence, physical terms not explicitly included in the calculation are treated on
the same footing with the truncation to a finite model space. In this approach,
we review results for both nuclear and trapped atomic systems, for which the
effective theories are formally similar, albeit describing different underlying
physics. Finally, the application of the EFT method of constructing effective
interactions to Gamow shell model is briefly discussed.Comment: 56 pages, 26 figure
Geologic carbon sources may confound ecosystem carbon balance estimates: Evidence from a semiarid steppe in the southeast of Spain
At a semiarid steppe site located in the SE of Spain, relatively large CO2 emissions were measured that could not be attributed to the ecosystem activity alone. Since the study site was located in a tectonically active area, it was hypothesized that a part of the measured CO2 was of geologic origin. This investigation included a survey of soil CO2 efflux, together with carbon isotope analyses of the CO2 in the soil atmosphere, soil CO2 efflux (ie, Keeling plots), groundwater and local thermal springs. These measurements confirmed the ... Articoli in Schola
Ruthenium(II) and Osmium(II) Vinyl Complexes as Highly Sensitive and Selective Chromogenic and Fluorogenic Probes for the Sensing of Carbon Monoxide in Air
[EN] The detection of carbon monoxide in solution and air has been achieved using simple, inexpensive systems based on the vinyl complexes [M(CH=CHR)Cl(CO)(BTD)(PPh3)2] (R=aryl, BTD=2,1,3-benzothiadiazole). Depending on the nature of the vinyl group, chromogenic and fluorogenic responses signalled the presence of this odourless, tasteless, invisible, and toxic gas. Solutions of the complexes in CHCl3 underwent rapid change between easily differentiated colours when exposed to air samples containing CO. More significantly, the adsorption of the complexes on silica produced colorimetric probes for the
naked-eye detection of CO in the gas phase. Structural data for key species before and after the addition of CO were obtained by means of single X-ray diffraction studies. In all
cases, the ruthenium and osmium vinyl complexes studied showed a highly selective response to CO with exceptionally low detection limits. Naked-eye detection of CO at concentrations as low as 5 ppb in air was achieved with the onset of toxic levels (i.e., 100 ppm), thus resulting in a remarkably clear colour change. Moreover, complexes bearing pyrenyl, naphthyl, and phenanthrenyl moieties were fluorescent, and greater sensitivities were achieved (through turn-on emission fluorescence) in the presence of CO both in solution and air. This behaviour was explored computationally using time-dependent density functional theory (TDDFT) experiments. In addition, the systems were shown to be selective
for CO over all other gases tested, including water vapour and common organic solvents. Supporting the metal complexes on cellulose strips for use in an existing optoelectronic
device allows numerical readings for the CO concentration to be obtained and provision of an alarm system.The authors wish to express their gratitude to the Spanish Government (project MAT2012-38429-C04) and Generalitat Valenciana (project PROMETEOII/2014/047) for their support. M.E.M. is grateful to the Spanish Ministerio de Ciencia e Innovacion for an FPU grant and a short-stay fellowship, which allowed this profitable collaboration. C.M.-H. thanks the Spanish Ministry of Economy and Competitiveness for her grant. A.T. gratefully acknowledges the support of the Leverhulme Trust (Grant RPG-2012-634) for a studentship. The authors thank Prof. C. K. Williams, Prof. N. J. Long, and Dr P. Hunt (Imperial College, UK) for the use of apparatus and assistance.Toscani, A.; Marín-Hernández, C.; Moragues Pons, ME.; Sancenón Galarza, F.; Dingwall, P.; Brown, NJ.; Martínez-Máñez, R.... (2015). Ruthenium(II) and Osmium(II) Vinyl Complexes as Highly Sensitive and Selective Chromogenic and Fluorogenic Probes for the Sensing of Carbon Monoxide in Air. Chemistry - A European Journal. 21(41):14529-14538. https://doi.org/10.1002/chem.201501843S1452914538214
- …