10,292 research outputs found
Spontaneous Supersymmetric Generation of an Indeterminate Mass Scale and a Possible Light Sterile Neutrino
If a global continuous symmetry of a supersymmetric field theory is
spontaneously broken while preserving the supersymmetry, the resulting theory
has a massless superfield. One of its two bosonic degrees of freedom is the
familiar phase rotation of the usual massless Nambu-Goldstone boson, but the
other is a scale transformation. An indeterminate mass scale is thus generated.
In the fermion sector, a seesaw texture appears which may be suitable for a
possible light sterile neutrino. This feature persists even after the gauging
of the continuous symmetry or the breaking of the supersymmetry to resolve the
aforementioned mass-scale ambiguity.Comment: 9 pages, expanded to include the discussion of a possible sterile
neutrin
Large Scale Baryon Isocurvature Inhomogeneities
Big bang nucleosynthesis constraints on baryon isocurvature perturbations are
determined. A simple model ignoring the effects of the scale of the
perturbations is first reviewed. This model is then extended to test the claim
that large amplitude perturbations will collapse, forming compact objects and
preventing their baryons from contributing to the observed baryon density. It
is found that baryon isocurvature perturbations are constrained to provide only
a slight increase in the density of baryons in the universe over the standard
homogeneous model. In particular it is found that models which rely on power
laws and the random phase approximation for the power spectrum are incompatible
with big bang nucleosynthesis unless an {\em ad hoc}, small scale cutoff is
included.Comment: 11pages + 8figures, LaTeX (2.09), postscript figures available via
anonymous ftp from oddjob.uchicago.edu:/ftp/ibbn/fig?.ps where ?=1-8 or via
email from [email protected], Fermilab-Pub-94/???-A and UMN-TH-1307/9
Testing Bekenstein's Relativistic MOND gravity with Lensing Data
We propose to use multiple-imaged gravitational lenses to set limits on
gravity theories without dark matter, specificly TeVeS (Bekenstein 2004), a
theory which is consistent with fundamental relativistic principles and the
phenomenology of MOdified Newtonian Dynamics (MOND) theory. After setting the
framework for lensing and cosmology, we derive analytically the deflection
angle for the point lens and the Hernquist galaxy profile, and fit
galaxy-quasar lenses in the CASTLES sample. We do this with three methods,
fitting the observed Einstein ring sizes, the image positions, or the flux
ratios. In all cases we consistently find that stars in galaxies in MOND/TeVeS
provide adequate lensing. Bekenstein's toy function provides more
efficient lensing than the standard MOND function. But for a handful of
lenses [indicated in Table 2,3, fig 16] a good fit would require a lens mass
orders of magnitude larger/smaller than the stellar mass derived from
luminosity unless the modification function and modification scale
for the universal gravity were allowed to be very different from what spiral
galaxy rotation curves normally imply. We discuss the limitation of present
data and summarize constraints on the MOND function. We also show that
the simplest TeVeS "minimal-matter" cosmology, a baryonic universe with a
cosmological constant, can fit the distance-redshift relation from the
supernova data, but underpredicts the sound horizon size at the last
scattering. We conclude that lensing is a promising approach to differentiate
laws of gravity (see also astro-ph/0512425).Comment: reduced to 17p, 16 figs, discussed cosmology and constraints on
mu-function, MNRAS accepte
Kinetics of Surfactant Adsorption at Fluid-Fluid Interfaces: Surfactant Mixtures
The adsorption at the interface between an aqueous solution of several
surface-active agents and another fluid (air or oil) phase is addressed
theoretically. We derive the kinetic equations from a variation of the
interfacial free energy, solve them numerically and provide an analytic
solution for the simple case of a linear adsorption isotherm. Calculating
asymptotic solutions analytically, we find the characteristic time scales of
the adsorption process and observe the behavior of the system at various
temporal stages. In particular, we relate the kinetic behavior of the mixture
to the properties of its individual constituents and find good agreement with
experiments. In the case of kinetically limited adsorption, the mixture
kinetics is found to be considerably different from that of the
single-surfactant solutions because of strong coupling between the species.Comment: 19 pages, 7 figures, to be published in Langmui
A creature with a hundred waggly tails: intrinsically disordered proteins in the ribosome
This article is made available for unrestricted research re-use and secondary analysis in any form or by any means with acknowledgement of the original source. These permissions are granted for the duration of the World Health Organization (WHO) declaration of COVID-19 as a global pandemic.Intrinsic disorder (i.e., lack of a unique 3-D structure) is a common phenomenon, and many biologically active proteins are disordered as a whole, or contain long disordered regions. These intrinsically disordered proteins/regions constitute a significant part of all proteomes, and their functional repertoire is complementary to functions of ordered proteins. In fact, intrinsic disorder represents an important driving force for many specific functions. An illustrative example of such disorder-centric functional class is RNA-binding proteins. In this study, we present the results of comprehensive bioinformatics analyses of the abundance and roles of intrinsic disorder in 3,411 ribosomal proteins from 32 species. We show that many ribosomal proteins are intrinsically disordered or hybrid proteins that contain ordered and disordered domains. Predicted globular domains of many ribosomal proteins contain noticeable regions of intrinsic disorder. We also show that disorder in ribosomal proteins has different characteristics compared to other proteins that interact with RNA and DNA including overall abundance, evolutionary conservation, and involvement in protein–protein interactions. Furthermore, intrinsic disorder is not only abundant in the ribosomal proteins, but we demonstrate that it is absolutely necessary for their various functions
Targeting telomerase for cancer therapeutics
One of the hallmarks of advanced malignancies is continuous cell growth and this almost universally correlates with the reactivation of telomerase. Although there is still much we do not understand about the regulation of telomerase, it remains a very attractive and novel target for cancer therapeutics. Several clinical trials have been initiated, and in this review we highlight some of the most promising approaches and conclude by speculating on the role of telomerase in cancer stem cells
Should Tort Damages Be Multiplied?
The notion that damages should be multiplied by the reciprocal of the probability of punishment is one of the basic lessons of the law and economics literature. However, the simple l/p multiplier turns out be inapplicable in the civil damages setting. The multiplier that brings about first-best deterrence must be chosen by striking a balance between the supply of lawsuits and the need to internalize costs. Moreover, given the costs of litigation, a multiplier that minimizes overall social costs (in contrast to achieving first-best deterrence) may need to be set at a level that effectively bars many claims. This article derives optimal damage multipliers for a costly civil litigation system and examines the conflicting implications of deterrence and social cost minimization as objectives in the design of an optimal multiplier. An empirical application suggests that the first-best deterrence multiplier for the tort system is roughly equal to two
RNA Sequencing Reveals Novel Transcripts from Sympathetic Stellate Ganglia During Cardiac Sympathetic Hyperactivity.
Cardiovascular disease is the most prevalent age-related illness worldwide, causing approximately 15 million deaths every year. Hypertension is central in determining cardiovascular risk and is a strong predictive indicator of morbidity and mortality; however, there remains an unmet clinical need for disease-modifying and prophylactic interventions. Enhanced sympathetic activity is a well-established contributor to the pathophysiology of hypertension, however the cellular and molecular changes that increase sympathetic neurotransmission are not known. The aim of this study was to identify key changes in the transcriptome in normotensive and spontaneously hypertensive rats. We validated 15 of our top-scoring genes using qRT-PCR, and network and enrichment analyses suggest that glutamatergic signalling plays a key role in modulating Ca2+ balance within these ganglia. Additionally, phosphodiesterase activity was found to be altered in stellates obtained from the hypertensive rat, suggesting that impaired cyclic nucleotide signalling may contribute to disturbed Ca2+ homeostasis and sympathetic hyperactivity in hypertension. We have also confirmed the presence of these transcripts in human donor stellate samples, suggesting that key genes coupled to neurotransmission are conserved. The data described here may provide novel targets for future interventions aimed at treating sympathetic hyperactivity associated with cardiovascular disease and other dysautonomias
Investigating the source of Planck-detected AME: high resolution observations at 15 GHz
The Planck 28.5 GHz maps were searched for potential Anomalous Microwave
Emission (AME) regions on the scale of or smaller, and several
new regions of interest were selected. Ancillary data at both lower and higher
frequencies were used to construct spectral energy distributions (SEDs), which
seem to confirm an excess consistent with spinning dust models. Here we present
higher resolution observations of two of these new regions with the Arcminute
Microkelvin Imager Small Array (AMI SA) between 14 and 18 GHz to test for the
presence of a compact (10 arcmin or smaller) component. For
AME-G107.1+5.2, dominated by the {\sc Hii} region S140, we find evidence for
the characteristic rising spectrum associated with the either the spinning dust
mechanism for AME or an ultra/hyper-compact \textsc{Hii} region across the AMI
frequency band, however for AME-G173.6+2.8 we find no evidence for AME on
scales of arcmin.Comment: 13 pages, 8 figures, 4 tables. Submitted to Advances in Astronomy AME
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