607 research outputs found
The human papillomavirus 16 E2 protein is stabilised in S phase
The human papillomavirus 16 E2 protein regulates transcription from, and replication of, the viral genome and is also required for segregation of the viral genome via interaction with mitotic bodies. To regulate DNA replication E2 interacts with sequences around the origin of replication and recruits the viral helicase E1 via a protein-protein interaction, which then initiates viral genome replication. The replication role of E2 must originally function in a host cell S phase. In this report, we demonstrate that E2 is stabilised in the S phase of the cell cycle and that this stabilisation is accompanied by an increase in phosphorylation of the protein. This increased phosphorylation and stability are likely required for optimum viral DNA replication and therefore identification of the enzymes involved in regulating these properties of E2 will provide targets for therapeutic intervention in the viral life cycle. Preliminary studies have identified E2 as a Cdk2 substrate demonstrating this enzyme as a candidate kinase for mediating the in vivo phosphorylation of HPV16 E2
One-loop corrections to the metastable vacuum decay
We evaluate the one-loop prefactor in the false vacuum decay rate in a theory
of a self interacting scalar field in 3+1 dimensions. We use a numerical
method, established some time ago, which is based on a well-known theorem on
functional determinants. The proper handling of zero modes and of
renormalization is discussed. The numerical results in particular show that
quantum corrections become smaller away from the thin-wall case. In the
thin-wall limit the numerical results are found to join into those obtained by
a gradient expansion.Comment: 31 pages, 7 figure
Granular Solid Hydrodynamics
Granular elasticity, an elasticity theory useful for calculating static
stress distribution in granular media, is generalized to the dynamic case by
including the plastic contribution of the strain. A complete hydrodynamic
theory is derived based on the hypothesis that granular medium turns
transiently elastic when deformed. This theory includes both the true and the
granular temperatures, and employs a free energy expression that encapsulates a
full jamming phase diagram, in the space spanned by pressure, shear stress,
density and granular temperature. For the special case of stationary granular
temperatures, the derived hydrodynamic theory reduces to {\em hypoplasticity},
a state-of-the-art engineering model.Comment: 42 pages 3 fi
Non--power law behavior of the radial profile of phase--space density of halos
We study the pseudo phase-space density, , of
CDM dark matter halos with and without baryons (baryons+DM, and pure
DM), by using the model introduced in Del Popolo (2009), which takes into
account the effect of dynamical friction, ordered and random angular momentum,
baryons adiabatic contraction and dark matter baryons interplay. We examine the
radial dependence of over 9 orders of magnitude in radius
for structures on galactic and cluster of galaxies scales. We find that
is approximately a power-law only in the range of halo
radius resolved by current simulations (down to 0.1% of the virial radius)
while it has a non-power law behavior below the quoted scale, with inner
profiles changing with mass. The non-power-law behavior is more evident for
halos constituted both of dark matter and baryons while halos constituted just
of dark matter and with angular momentum chosen to reproduce a
Navarro-Frenk-White (NFW) density profile, are characterized by an
approximately power-law behavior. The results of the present paper lead to
conclude that density profiles of the NFW type are compatible with a power-law
behavior of , while those flattening to the halo center,
like those found in Del Popolo (2009) or the Einasto profile, or the Burkert
profile, cannot produce radial profile of the pseudo-phase-space density that
are power-laws at all radii. The results argue against universality of the
pseudo phase-space density and as a consequence argue against universality of
density profiles constituted by dark matter and baryons as also discussed in
Del Popolo (2009).Comment: 20 pages; 7 figs. arXiv admin note: substantial text overlap with
arXiv:0906.4447 and arXiv:1012.432
Order and Chaos in some Trigonometric Series: Curious Adventures of a Statistical Mechanic
This paper tells the story how a MAPLE-assisted quest for an interesting
undergraduate problem in trigonometric series led some "amateurs" to the
discovery that the one-parameter family of deterministic trigonometric series
\pzcS_p: t\mapsto \sum_{n\in\Nset}\sin(n^{-{p}}t), , exhibits both order
and apparent chaos, and how this has prompted some professionals to offer their
expert insights. It is proved that \pzcS_p(t) =
\alpha_p\rm{sign}(t)|t|^{1/{p}}+O(|t|^{1/{(p+1)}})\;\forall\;t\in\Rset, with
explicitly computed constant . Experts' commentaries are reproduced
stating the fluctuations of \pzcS_p(t) - \alpha_p{\rm{sign}}(t)|t|^{1/{p}}
are presumably not Gaussian. Inspired by a central limit type theorem of Marc
Kac, a well-motivated conjecture is formulated to the effect that the
fluctuations of the -th partial sum of \pzcS_p(t),
when properly scaled, do converge in distribution to a standard Gaussian when
, though --- provided that is chosen so that the frequencies
\{n^{-p}\}_{n\in\Nset} are rationally linear independent; no conjecture has
been forthcoming for rationally dependent \{n^{-p}\}_{n\in\Nset}. Moreover,
following other experts' tip-offs, the interesting relationship of the
asymptotics of \pzcS_p(t) to properties of the Riemann function is
exhibited using the Mellin transform.Comment: Based on the invited lecture with the same title delivered by the
author on Dec.19, 2011 at the 106th Statistical Mechanics Meeting at Rutgers
University in honor of Michael Fisher, Jerry Percus, and Ben Widom. (19
figures, colors online). Comments of three referees included. Conjecture 1
revised. Accepted for publication in J. Stat. Phy
Spinor condensates and light scattering from Bose-Einstein condensates
These notes discuss two aspects of the physics of atomic Bose-Einstein
condensates: optical properties and spinor condensates. The first topic
includes light scattering experiments which probe the excitations of a
condensate in both the free-particle and phonon regime. At higher light
intensity, a new form of superradiance and phase-coherent matter wave
amplification were observed. We also discuss properties of spinor condensates
and describe studies of ground--state spin domain structures and dynamical
studies which revealed metastable excited states and quantum tunneling.Comment: 58 pages, 33 figures, to appear in Proceedings of Les Houches 1999
Summer School, Session LXXI
Time-integrated luminosity recorded by the BABAR detector at the PEP-II e+e- collider
This article is the Preprint version of the final published artcile which can be accessed at the link below.We describe a measurement of the time-integrated luminosity of the data collected by the BABAR experiment at the PEP-II asymmetric-energy e+e- collider at the ϒ(4S), ϒ(3S), and ϒ(2S) resonances and in a continuum region below each resonance. We measure the time-integrated luminosity by counting e+e-→e+e- and (for the ϒ(4S) only) e+e-→μ+μ- candidate events, allowing additional photons in the final state. We use data-corrected simulation to determine the cross-sections and reconstruction efficiencies for these processes, as well as the major backgrounds. Due to the large cross-sections of e+e-→e+e- and e+e-→μ+μ-, the statistical uncertainties of the measurement are substantially smaller than the systematic uncertainties. The dominant systematic uncertainties are due to observed differences between data and simulation, as well as uncertainties on the cross-sections. For data collected on the ϒ(3S) and ϒ(2S) resonances, an additional uncertainty arises due to ϒ→e+e-X background. For data collected off the ϒ resonances, we estimate an additional uncertainty due to time dependent efficiency variations, which can affect the short off-resonance runs. The relative uncertainties on the luminosities of the on-resonance (off-resonance) samples are 0.43% (0.43%) for the ϒ(4S), 0.58% (0.72%) for the ϒ(3S), and 0.68% (0.88%) for the ϒ(2S).This work is supported by the US Department of Energy and National Science Foundation, the Natural Sciences and Engineering Research Council (Canada), the Commissariat à l’Energie Atomique and Institut National de Physique Nucléaire et de Physiquedes Particules (France), the Bundesministerium für Bildung und Forschung and Deutsche Forschungsgemeinschaft (Germany), the Istituto Nazionale di Fisica Nucleare (Italy), the Foundation for Fundamental Research on Matter (The Netherlands), the Research Council of Norway, the Ministry of Education and Science of the Russian Federation, Ministerio de Ciencia e Innovación (Spain), and the Science and Technology Facilities Council (United Kingdom). Individuals have received support from the Marie-Curie IEF program (European Union) and the A.P. Sloan Foundation (USA)
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