1,256 research outputs found
Shocks and Universal Statistics in (1+1)-Dimensional Relativistic Turbulence
We propose that statistical averages in relativistic turbulence exhibit
universal properties. We consider analytically the velocity and temperature
differences structure functions in the (1+1)-dimensional relativistic
turbulence in which shock waves provide the main contribution to the structure
functions in the inertial range. We study shock scattering, demonstrate the
stability of the shock waves, and calculate the anomalous exponents. We comment
on the possibility of finite time blowup singularities.Comment: 37 pages, 7 figure
The Pure Spinor Formulation of Superstrings
In this lectures we outline the construction of pure spinor superstrings. We
consider both the open and closed pure spinor superstrings in critical and
noncritical dimensions and on flat and curved target spaces with RR flux. We
exhibit the integrability properties of pure spinor superstrings on curved
backgrounds with RR fluxes.Comment: These lectures have been given in the RTN Winter School on Strings,
Supergravity and Gauge Theories, CERN (2008). 32 pages, a typo correcte
New relations for correlation functions in Navier-Stokes turbulence
We consider the steady-state statistics of turbulence sustained by a
large-scale force. The Kolmogorov flux relation (4/5-law) is shown to be a
particular case of the general relation on the current-density correlation
function. Using that, we derive an analog of the flux relation for compressible
turbulence and a new exact relation for incompressible turbulence.Comment: 11 page
The Spo13/Meikin pathway confines the onset of gamete differentiation to meiosis II in yeast
Sexual reproduction requires genome haploidization by the two divisions of meiosis and a differentiation program to generate gametes. Here, we have investigated how sporulation, the yeast equivalent of gamete differentiation, is coordinated with progression through meiosis. Spore differentiation is initiated at metaphase II when a membrane-nucleating structure, called the meiotic plaque, is assembled at the centrosome. While all components of this structure accumulate already at entry into meiosis I, they cannot assemble because centrosomes are occupied by Spc72, the receptor of the gamma-tubulin complex. Spc72 is removed from centrosomes by a pathway that depends on the polo-like kinase Cdc5 and the meiosis-specific kinase Ime2, which is unleashed by the degradation of Spo13/Meikin upon activation of the anaphase-promoting complex at anaphase I. Meiotic plaques are finally assembled upon reactivation of Cdk1 at entry into metaphase II. This unblocking-activation mechanism ensures that only single-copy genomes are packaged into spores and might serve as a paradigm for the regulation of other meiosis II-specific processes
Gravitational F-terms of N=1 Supersymmetric Gauge Theories
We consider four-dimensional N=1 supersymmetric gauge theories in a
supergravity background. We use generalized Konishi anomaly equations and
R-symmetry anomaly to compute the exact perturbative and non-perturbative
gravitational F-terms. We study two types of theories: The first model breaks
supersymmetry dynamically, and the second is based on a gauge group. The
results are compared with the corresponding vector models. We discuss the
diagrammatic expansion of the theory.Comment: LaTeX2e, 23 pages, 2 figures. Added a reference and converted into
JHEP styl
On the fermionic T-duality of the AdS_4 \times CP^3 sigma-model
In this note we consider a fermionic T-duality of the coset realization of
the type IIA sigma-model on AdS_4 \times CP^3 with respect to the three flat
directions in AdS_4, six of the fermionic coordinates and three of the CP^3
directions. We show that the Buscher procedure fails as it leads to a singular
transformation and discuss the result and its implications.Comment: LaTeX2e, 9 pages, no figures, JHEP style; v2: minor clarifications;
v3: typos fixed, matches the published versio
One-Parameter Squeezed Gaussian States of Time-Dependent Harmonic Oscillator and Selection Rule for Vacuum States
By using the invariant method we find one-parameter squeezed Gaussian states
for both time-independent and time-dependent oscillators. The squeezing
parameter is expressed in terms of energy expectation value for
time-independent case and represents the degree of mixing positive and negative
frequency solutions for time-dependent case. A {\it minimum uncertainty
proposal} is advanced to select uniquely vacuum states at each moment of time.
We show that the Gaussian states with minimum uncertainty coincide with the
true vacuum state for time-independent oscillator and the Bunch-Davies vacuum
for a massive scalar field in a de Sitter spacetime.Comment: 13 Pages, ReVTeX, no figure
Tracking the oxygen isotopic signature from the rainfall to the speleothems in Ortigosa de Cameros caves (La Rioja, Spain)
A one-year monitoring survey has been carried out in La Paz and La Viña Caves in the Ortigosa de Cameros Cave System (NE Iberian Peninsula), in order to track the oxygen isotope signal from rainfall to speleothem calcite, assessing the ability of this signal to retain environmental information. Oxygen isotope signals of rainfall events, drip water —sampled every three months—, and speleothem calcite, precipitated over three-months, are compared. Water dripping follows precipitation events in winter, spring and summer, more closely in the near-surface drip points than in the deeper ones. In autumn, dripping is delayed with respect to rainfall, suggesting that water stays in the epikarst before dripping resumes after summer. This delay causes a deviation of the total drip water signal (average δ<sup>18</sup>O=−8.39‰ V-SMOW) from the rainfall signal (average δ<sup>18</sup>O=−7.41‰ V-SMOW). On the contrary, in winter the isotopic signal of drip water keeps the rainfall signal. Calcite isotopic signal (total average δ<sup>18</sup>O=−6.83‰ V-PDB) shows a small offset (0.62–0.75%) with respect to the signal predicted by drip water oxygen composition; this points to a limited kinetic effect in calcite precipitation, therefore calcite retains the signal of rainfall, especially in winter.<br><br>Durante un año se han monitorizado las cuevas de La Paz y La Viña en el Sistema de Cuevas de Ortigosa de Cameros (NE de la PenÃnsula Ibérica) para rastrear la señal isotópica del oxÃgeno desde la lluvia a la calcita espeleotémica, y asà valorar la capacidad de esta señal para conservar información medioambiental. Se han comparado las señales isotópicas del oxÃgeno de los eventos de la lluvia, el agua de goteo (muestreada trimestralmente) y la calcita espeleotémica, precipitada también durante cada trimestre. El goteo en las cuevas responde a la precipitación en invierno, primavera y verano, más estrechamente en los puntos más próximos a la superficie que en los profundos. En otoño hay un retraso entre la lluvia y el goteo, lo que sugiere que el agua permanece por un tiempo en el epikarst, antes de que se reanude el goteo después del verano. Este retraso provoca que la señal isotópica del agua de goteo (media total de δ<sup>18</sup>O=−8.39‰ V-SMOW) se desvÃe de la señal de la lluvia (media de δ<sup>18</sup>O=−7,41‰ V-SMOW). Por el contrario, en invierno la señal isotópica del agua de goteo es muy semejante a la de la lluvia. La composición isotópica de la calcita espeleotémica (media total de δ<sup>18</sup>O=−6,83‰ V-PDB) presenta un pequeño desfase (0,62–0,75%) respecto al valor que le corresponderÃa por la composición isotópica del agua de goteo; esto indica que los efectos cinéticos durante la precipitación de la calcita son limitados, por lo que ésta conserva la señal de la lluvia, especialmente en invierno
Perturbative Computation of Glueball Superpotentials for SO(N) and USp(N)
We use the superspace method of hep-th/0211017 to prove the matrix model
conjecture for N=1 USp(N) and SO(N) gauge theories in four dimensions. We
derive the prescription to relate the matrix model to the field theory
computations. We perform an explicit calculation of glueball superpotentials.
The result is consistent with field theory expectations.Comment: 24 pages, 10 figure
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