192 research outputs found
High Efficiency RNA Extraction From Sperm Cells Using Guanidinium Thiocyanate Supplemented With Tris(2-Carboxyethyl)Phosphine
The extraction of high-quality ribonucleic acid (RNA) from tissues and cells is a key step in many biological assays. Guanidinium thiocyanate-phenol-chloroform (AGPC) is a widely used and efficient method to obtain pure RNA from most tissues and cells. However, it is not efficient with some cells like sperm cells because they are resistant to chaotropic lysis solutions containing guanidinium thiocyanate such as Buffer RLT+ and Trizol. Here, we show that disulfide bonds are responsible for the chemical resistance of sperm cells to RNA extraction reagents. We show that while β-mercaptoethanol (βME) can increase sperm lysis in Buffer RLT+, it has no effect in Trizol and leaves sperm cells intact. We measured the reduction of disulfide bonds in 2,2′-dithiodipyridine (DTDP) and observed that βME has a pH-dependent activity in chaotropic solutions, suggesting that pH is a limiting factor. We identified tris(2-carboxyethyl)phosphine (TCEP) as an efficient lysis enhancer of AGPC solutions that can retain reducing activity even at acidic pH. Trizol supplemented with TCEP allows the complete and rapid lysis of sperm cells, increasing RNA yield by 100-fold and resulting in RNA with optimal quality for reverse transcription and polymerase chain reaction. Our findings highlight the importance of efficient cell lysis and extraction of various macromolecules for bulk and single-cell assays, and can be applied to other lysis-resistant cells and vesicles, thereby optimizing the amount of required starting material and animals
Upper and Lower Limits on Neutralino WIMP Mass and Spin--Independent Scattering Cross Section, and Impact of New (g-2)_{mu} Measurement
We derive the allowed ranges of the spin--independent interaction cross
section \sigsip for the elastic scattering of neutralinos on proton for wide
ranges of parameters of the general Minimal Supersymmetric Standard Model. We
investigate the effects of the lower limits on Higgs and superpartner masses
from colliders, as well as the impact of constraints from \bsgamma and the
new measurement of \gmtwo on the upper and lower limits on \sigsip. We
further explore the impact of the neutralino relic density, including
coannihilation, and of theoretical assumptions about the largest allowed values
of the supersymmetric parameters. For , requiring the latter to lie
below 1\tev leads to \sigsip\gsim 10^{-11}\pb at \mchi\sim100\gev and
\sigsip\gsim 10^{-8}\pb at \mchi\sim1\tev. When the supersymmetric
parameters are allowed above 1\tev, for 440\gev \lsim \mchi\lsim 1020 \gev
we derive a {\em parameter--independent lower limit} of \sigsip \gsim 2\times
10^{-12}\pb. (No similar lower limits can be set for nor for
1020\gev\lsim\mchi\lsim2.6\tev.) Requiring \abundchi<0.3 implies a {\em
parameter--independent upper limit} \mchi\lsim2.6\tev. The new \epem--based
measurement of restricts \mchi\lsim 350\gev at CL
and \mchi\lsim515\gev at CL, and implies . The largest
allowed values of \sigsip have already become accessible to recent
experimental searches.Comment: LaTeX, 17 pages, 9 eps figures. Version to appear in JHE
Single-Cell Multiomics Techniques: From Conception to Applications
Recent advances in methods for single-cell analyses and barcoding strategies have led to considerable progress in research. The development of multiplexed assays offers the possibility to conduct parallel analyses of multiple factors and processes for comprehensive characterization of cellular and molecular states in health and disease. These technologies have expanded extremely rapidly in the past years and constantly evolve and provide better specificity, precision and resolution. This review summarizes recent progress in single-cell multiomics approaches, and focuses, in particular, on the most innovative techniques that integrate genome, epigenome and transcriptome profiling. It describes the methodologies, discusses their advantages and limitations, and explains how they have been applied to studies on cell heterogeneity and differentiation, and epigenetic reprogramming.
Keywords: chromatin accessibility; epigenomics; genomics; multiomics; single-cell; transcriptomic
Dark matter in gravity-mediated supersymmetry breaking
In R parity conserving supersymmetric theories the lightest superpartner
(LSP) is stable. The LSPs may comprise a large fraction of the energy density
of the current universe, which would lead to dramatic astrophysical
consequences. In this talk, I discuss some of the main lessons we have learned
about supersymmetric models from relic abundance considerations of the LSP.Comment: 6 pages, LaTeX with espcrc2.sty, to be published in the "Proceedings
of the 5th International Conference on Supersymmetries in Physics (SUSY 97)",
Philadelphia, Pennsylvania, May 27-31, 199
Signatures of Axinos and Gravitinos at Colliders
The axino and the gravitino are well-motivated candidates for the lightest
supersymmetric particle (LSP) and also for cold dark matter in the Universe.
Assuming that a charged slepton is the next-to-lightest supersymmetric particle
(NLSP), we show how the NLSP decays can be used to probe the axino LSP scenario
in hadronic axion models as well as the gravitino LSP scenario at the Large
Hadron Collider and the International Linear Collider. We show how one can
identify experimentally the scenario realized in nature. In the case of the
axino LSP, the NLSP decays will allow one to estimate the value of the axino
mass and the Peccei-Quinn scale.Comment: 20 pages, 5 figures, revised version as published in Phys.Lett.B
(comments on the experimental feasibility added
Bayesian approach and Naturalness in MSSM analyses for the LHC
The start of LHC has motivated an effort to determine the relative
probability of the different regions of the MSSM parameter space, taking into
account the present, theoretical and experimental, wisdom about the model.
Since the present experimental data are not powerful enough to select a small
region of the MSSM parameter space, the choice of a judicious prior probability
for the parameters becomes most relevant. Previous studies have proposed
theoretical priors that incorporate some (conventional) measure of the
fine-tuning, to penalize unnatural possibilities. However, we show that such
penalization arises from the Bayesian analysis itself (with no ad hoc
assumptions), upon the marginalization of the mu-parameter. Furthermore the
resulting effective prior contains precisely the Barbieri-Giudice measure,
which is very satisfactory. On the other hand we carry on a rigorous treatment
of the Yukawa couplings, showing in particular that the usual practice of
taking the Yukawas "as required", approximately corresponds to taking
logarithmically flat priors in the Yukawa couplings. Finally, we use an
efficient set of variables to scan the MSSM parameter space, trading in
particular B by tan beta, giving the effective prior in the new parameters.
Beside the numerical results, we give accurate analytic expressions for the
effective priors in all cases. Whatever experimental information one may use in
the future, it is to be weighted by the Bayesian factors worked out here.Comment: LaTeX, 19 pages, 3 figure
The complete radiative corrections to the gaugino and Higgsino masses in the Minimal Supersymmetric Model
We determine the radiative corrections to the masses of the gauginos and
Higgsinos in the MSSM, including all sectors of the theory in a one-loop
calculation in the on-mass-shell renormalization scheme. We find that a gluino
which is massless at tree level receives a mass of between 0 and 3 GeV,
primarily due to the top/stop contribution. This radiatively generated mass
depends directly on the off-diagonal element of the squark mass matrix. In the
case of a massive gluino, its mass receives typically large corrections, as
large as 40\% for a 125 GeV gluino. We find that the contributions to the
neutralino and chargino mass corrections from the gauge/Higgs/gaugino/Higgsino
sector are typically +-1%. The lightest neutralino, which can receive
corrections larger than 25%, receives 5% corrections over most of the parameter
space. We combine our results with the results of LEP and CDF searches to
obtain the lower bounds on the neutralino and chargino masses at one-loop. We
also demonstrate how the radiative corrections affect the presently excluded
region of parameter space.Comment: 16 pages, JHU-TIPAC-940001, PURD-TH-94-04. 6 uuencoded postscript
figures included. Uncomment the line "%\input epsf" to embed the figures in
the tex
A description of the neutralino observables in terms of projectors
Applying Jarlskog's treatment of the CKM matrix, to the neutralino mass
matrix in MSSM for real soft gaugino SUSY breaking and -parameters, we
construct explicit analytical expressions for the four projectors which acting
on any neutralino state project out the mass eigenstates. Analytical
expressions for the neutralino mass eigenvalues in terms of the various SUSY
parameters, are also given. It is shown that these projectors and mass
eigenvalues are sufficient to describe any physical observable involving
neutralinos, to any order of perturbation theory. As an example, the cross section at tree level is given in
terms of these projectors. The expected magnitude of their various matrix
elements in plausible SUSY scenarios is also discussed.Comment: 14 pages, no figures. Version to appear in Phys. Rev. D. e-mail:
[email protected]
Gravitino Dark Matter and Cosmological Constraints
The gravitino is a promising candidate for cold dark matter. We study
cosmological constraints on scenarios in which the gravitino is the lightest
supersymmetric particle and a charged slepton the next-to-lightest
supersymmetric particle (NLSP). We obtain new results for the hadronic
nucleosynthesis bounds by computing the 4-body decay of the NLSP slepton into
the gravitino, the associated lepton, and a quark-antiquark pair. The bounds
from the observed dark matter density are refined by taking into account
gravitinos from both late NLSP decays and thermal scattering in the early
Universe. We examine the present free-streaming velocity of gravitino dark
matter and the limits from observations and simulations of cosmic structures.
Assuming that the NLSP sleptons freeze out with a thermal abundance before
their decay, we derive new bounds on the slepton and gravitino masses. The
implications of the constraints for cosmology and collider phenomenology are
discussed and the potential insights from future experiments are outlined. We
propose a set of benchmark scenarios with gravitino dark matter and long-lived
charged NLSP sleptons and describe prospects for the Large Hadron Collider and
the International Linear Collider.Comment: 51 pages, 20 figures, revised version matches published version
(results unchanged, JHEP style used, figures replaced with new high-quality
figures, typos corrected, references added
Exploring the Local Grammar of Evaluation: The Case of Adjectival Patterns in American and Italian Judicial Discourse
Based on a 2-million word bilingual comparable corpus of American and Italian judgments, this paper tests the applicability of a local grammar to study evaluative phraseology in judicial discourse in English and Italian. In particular, the study compares the use of two patterns: v-link + ADJ + that pattern / copula + ADJ + che and v-link + ADJ + to-infinitive pattern / copula + ADJ + verbo all’infinito in the disciplinary genre of criminal judgments delivered by the US Supreme Court and the Italian Corte Suprema di Cassazione. It is argued that these two patterns represent a viable and efficient diagnostic tool for retrieving instances of evaluative language and they represent an ideal starting point and a relevant unit of analysis for a cross-language analysis of evaluation in domainrestricted specialised discourse. Further, the findings provided shed light on important interactions occurring among major interactants involved in the judicial discourse
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