545 research outputs found
Elogio de la contraconducta
Entre diciembre de 1976 y mayo de 1984 Michel Foucault no publicó ningún nuevo libro. Sin embargo, lejos de ser éste un período de silencio, Foucault concentró en este tiempo una extraordinaria cantidad de actividad intelectual en ensayos, conferencias, entrevistas, y especialmente en sus cursos del Collège de France. Sin tener acceso a estos cursos, era extremadamente difícil entender la reorientación del trabajo de Foucault, de un análisis de las estrategias y tácticas de poder inmanentes e..
Anisotropy and non-universality in scaling laws of the large scale energy spectrum in rotating turbulence
Rapidly rotating turbulent flow is characterized by the emergence of columnar
structures that are representative of quasi-two dimensional behavior of the
flow. It is known that when energy is injected into the fluid at an
intermediate scale , it cascades towards smaller as well as larger scales.
In this paper we analyze the flow in the \textit{inverse cascade} range at a
small but fixed Rossby number, {}. Several
{numerical simulations with} helical and non-helical forcing functions are
considered in periodic boxes with unit aspect ratio. In order to resolve the
inverse cascade range with {reasonably} large Reynolds number, the analysis is
based on large eddy simulations which include the effect of helicity on eddy
viscosity and eddy noise. Thus, we model the small scales and resolve
explicitly the large scales. We show that the large-scale energy spectrum has
at least two solutions: one that is consistent with
Kolmogorov-Kraichnan-Batchelor-Leith phenomenology for the inverse cascade of
energy in two-dimensional (2D) turbulence with a {}
scaling, and the other that corresponds to a steeper {}
spectrum in which the three-dimensional (3D) modes release a substantial
fraction of their energy per unit time to 2D modes. {The spectrum that} emerges
{depends on} the anisotropy of the forcing function{,} the former solution
prevailing for forcings in which more energy is injected into 2D modes while
the latter prevails for isotropic forcing. {In the case of anisotropic forcing,
whence the energy} goes from the 2D to the 3D modes at low wavenumbers,
large-scale shear is created resulting in another time scale ,
associated with shear, {thereby producing} a spectrum for the
{total energy} with the 2D modes still following a {}
scaling
Flavourful Production at Hadron Colliders
We ask what new states may lie at or below the TeV scale, with sizable
flavour-dependent couplings to light quarks, putting them within reach of
hadron colliders via resonant production, or in association with Standard Model
states. In particular, we focus on the compatibility of such states with
stringent flavour-changing neutral current and electric-dipole moment
constraints. We argue that the broadest and most theoretically plausible
flavour structure of the new couplings is that they are hierarchical, as are
Standard Model Yukawa couplings, although the hierarchical pattern may well be
different. We point out that, without the need for any more elaborate or
restrictive structure, new scalars with "diquark" couplings to standard quarks
are particularly immune to existing constraints, and that such scalars may
arise within a variety of theoretical paradigms. In particular, there can be
substantial couplings to a pair of light quarks or to one light and one heavy
quark. For example, the latter possibility may provide a flavour-safe
interpretation of the asymmetry in top quark production observed at the
Tevatron. We thereby motivate searches for diquark scalars at the Tevatron and
LHC, and argue that their discovery represents one of our best chances for new
insight into the Flavour Puzzle of the Standard Model.Comment: 18 pp., 8 figures, references adde
Baryogenesis at Low Reheating Temperatures
We note that the maximum temperature during reheating can be much greater
than the reheating temperature at which the Universe becomes radiation
dominated. We show that the Standard Model anomalous -violating
processes can therefore be in thermal equilibrium for 1 GeV \simlt T_{r}\ll
100 GeV. Electroweak baryogenesis could work and the traditional upper bound
on the Higgs mass coming from the requirement of the preservation of the baryon
asymmetry may be relaxed. Alternatively, the baryon asymmetry may be
reprocessed by sphaleron transitions either from a asymmetry generated
by the Affleck-Dine mechanism or from a chiral asymmetry between and
in a Universe. Our findings are also relevant to the production
of the baryon asymmetry in large extra dimension models.Comment: 4 pages, version to appear in PRL: references added, new titl
Sequence Analysis of the Cloned mRNA Coding for Glyceraldehyde-3-Phosphate Dehydrogenase from Chicken Heart Muscle
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66279/1/j.1432-1033.1983.tb07239.x.pd
Analytical methods for describing charged particle dynamics in general focusing lattices using generalized Courant-Snyder theory
The dynamics of charged particles in general linear focusing lattices with quadrupole, skew-quadrupole, dipole, and solenoidal components, as well as torsion of the fiducial orbit and variation of beam energy is parametrized using a generalized Courant-Snyder (CS) theory, which extends the original CS theory for one degree of freedom to higher dimensions. The envelope function is generalized into an envelope matrix, and the phase advance is generalized into a 4D symplectic rotation, or a U(2) element. The 1D envelope equation, also known as the Ermakov-Milne-Pinney equation in quantum mechanics, is generalized to an envelope matrix equation in higher dimensions. Other components of the original CS theory, such as the transfer matrix, Twiss functions, and CS invariant (also known as the Lewis invariant) all have their counterparts, with remarkably similar expressions, in the generalized theory. The gauge group structure of the generalized theory is analyzed. By fixing the gauge freedom with a desired symmetry, the generalized CS parametrization assumes the form of the modified Iwasawa decomposition, whose importance in phase space optics and phase space quantum mechanics has been recently realized. This gauge fixing also symmetrizes the generalized envelope equation and expresses the theory using only the generalized Twiss function beta. The generalized phase advance completely determines the spectral and structural stability properties of a general focusing lattice. For structural stability, the generalized CS theory enables application of the Krein-Moser theory to greatly simplify the stability analysis. The generalized CS theory provides an effective tool to study coupled dynamics and to discover more optimized lattice designs in the larger parameter space of general focusing lattices.open3
Explosive instability due to 4-wave mixing
It is known that an explosive instability can occur when nonlinear waves
propagate in certain media that admit 3-wave mixing. The purpose of this paper
is to show that explosive instabilities can occur even in media that admit no
3-wave mixing. Instead, the instability is caused by 4-wave mixing: four
resonantly interacting wavetrains gain energy from a background, and all blow
up in a finite time. Unlike singularities associated with self-focussing, these
singularities can occur with no spatial structure - the waves blow up
everywhere in space, simultaneously
A Novel Tandem Mass Spectrometry Method for Rapid Confirmation of Medium- and Very Long-Chain acyl-CoA Dehydrogenase Deficiency in Newborns
BACKGROUND:Newborn screening for medium- and very long-chain acyl-CoA dehydrogenase (MCAD and VLCAD, respectively) deficiency, using acylcarnitine profiling with tandem mass spectrometry, has increased the number of patients with fatty acid oxidation disorders due to the identification of additional milder, and so far silent, phenotypes. However, especially for VLCADD, the acylcarnitine profile can not constitute the sole parameter in order to reliably confirm disease. Therefore, we developed a new liquid chromatography tandem mass spectrometry (LC-MS/MS) method to rapidly determine both MCAD- and/or VLCAD-activity in human lymphocytes in order to confirm diagnosis. METHODOLOGY:LC-MS/MS was used to measure MCAD- or VLCAD-catalyzed production of enoyl-CoA and hydroxyacyl-CoA, in human lymphocytes. PRINCIPAL FINDINGS:VLCAD activity in controls was 6.95+/-0.42 mU/mg (range 1.95 to 11.91 mU/mg). Residual VLCAD activity of 4 patients with confirmed VLCAD-deficiency was between 0.3 and 1.1%. Heterozygous ACADVL mutation carriers showed residual VLCAD activities of 23.7 to 54.2%. MCAD activity in controls was 2.38+/-0.18 mU/mg. In total, 28 patients with suspected MCAD-deficiency were assayed. Nearly all patients with residual MCAD activities below 2.5% were homozygous 985A>G carriers. MCAD-deficient patients with one other than the 985A>G mutation had higher MCAD residual activities, ranging from 5.7 to 13.9%. All patients with the 199T>C mutation had residual activities above 10%. CONCLUSIONS:Our newly developed LC-MS/MS method is able to provide ample sensitivity to correctly and rapidly determine MCAD and VLCAD residual activity in human lymphocytes. Importantly, based on measured MCAD residual activities in correlation with genotype, new insights were obtained on the expected clinical phenotype
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