15,168 research outputs found
Evolutionarily conserved mechanisms of male germline development in flowering plants and animals
Sexual reproduction is the main reproductive strategy of the overwhelming majority of eukaryotes. This suggests that the last eukaryotic common ancestor was able to reproduce sexually. Sexual reproduction reflects the ability to perform meiosis, and ultimately generating gametes, which are cells that carry recombined half sets of the parental genome and are able to fertilize. These functions have been allocated to a highly specialized cell lineage: the germline. Given its significant evolutionary conservation, it is to be expected that the germline programme shares common molecular bases across extremely divergent eukaryotic species. In the present review, we aim to identify the unifying principles of male germline establishment and development by comparing two very disparate kingdoms: plants and animals. We argue that male meiosis defines two temporally regulated gene expression programmes: the first is required for meiotic commitment, and the second is required for the acquisition of fertilizing ability. Small RNA pathways are a further key communality, ultimately ensuring the epigenetic stability of the information conveyed by the male germline
Estudio paleopatológico de la necrópolis mudéjar de la calle Colón, 3 (Novelda, Alicante)
X Congreso Nacional de Paleopatología. Univesidad Autónoma de Madrid, septiembre de 200
Complementarity of Galactic radio and collider data in constraining WIMP dark matter models
In this work we confront dark matter models to constraints that may be
derived from radio synchrotron radiation from the Galaxy, taking into account
the astrophysical uncertainties and we compare these to bounds set by
accelerator and complementary indirect dark matter searches. Specifically we
apply our analysis to three popular particle physics models. First, a generic
effective operator approach, in which case we set bounds on the corresponding
mass scale, and then, two specific UV completions, the Z' and Higgs portals. We
show that for many candidates, the radio synchrotron limits are competitive
with the other searches, and could even give the strongest constraints (as of
today) with some reasonable assumptions regarding the astrophysical
uncertainties.Comment: 22 pages, 12 figure
Disentangling correlated scatter in cluster mass measurements
The challenge of obtaining galaxy cluster masses is increasingly being
addressed by multiwavelength measurements. As scatters in measured cluster
masses are often sourced by properties of or around the clusters themselves,
correlations between mass scatters are frequent and can be significant, with
consequences for errors on mass estimates obtained both directly and via
stacking. Using a high resolution 250 Mpc/h side N-body simulation, combined
with proxies for observational cluster mass measurements, we obtain mass
scatter correlations and covariances for 243 individual clusters along ~96
lines of sight each, both separately and together. Many of these scatters are
quite large and highly correlated. We use principal component analysis (PCA) to
characterize scatter trends and variations between clusters. PCA identifies
combinations of scatters, or variations more generally, which are uncorrelated
or non-covariant. The PCA combination of mass measurement techniques which
dominates the mass scatter is similar for many clusters, and this combination
is often present in a large amount when viewing the cluster along its long
axis. We also correlate cluster mass scatter, environmental and intrinsic
properties, and use PCA to find shared trends between these. For example, if
the average measured richness, velocity dispersion and Compton decrement mass
for a cluster along many lines of sight are high relative to its true mass, in
our simulation the cluster's mass measurement scatters around this average are
also high, its sphericity is high, and its triaxiality is low.
Our analysis is based upon estimated mass distributions for fixed true mass.
Extensions to observational data would require further calibration from
numerical simulations, tuned to specific observational survey selection
functions and systematics.Comment: 18 pages, 12 figures, final version to appear in MNRAS, helpful
changes from referee and others incorporate
Identification of Globular Cluster Stars in RAVE data II: Extended tidal debris around NGC 3201
We report the identification of extended tidal debris potentially associated with the globular cluster NGC 3201, using the RAdial Velocity Experiment (RAVE) catalogue. We find the debris stars are located at a distance range of 1–7 kpc based on the forthcoming RAVE distance estimates. The derived space velocities and integrals of motion show interesting connections to NGC 3201, modulo uncertainties in the proper motions. Three stars, which are among the four most likely candidates for NGC 3201 tidal debris, are separated by 80° on the sky yet are well matched by the 12 Gyr, [Fe/H] = −1.5 isochrone appropriate for the cluster. This is the first time tidal debris around this cluster has been reported over such a large spatial extent, with implications for the cluster's origin and dynamical evolution
Naturalizing the Female Body: Social Control through Reproduction
Objective: To discuss alternatives to understand how the medical sciences have reduced the female body conceptually to its biological dimension as the foundation for its social control
Combined search for the standard model Higgs boson decaying to a bb pair using the full CDF data set
We combine the results of searches for the standard model Higgs boson based
on the full CDF Run II data set obtained from sqrt(s) = 1.96 TeV p-pbar
collisions at the Fermilab Tevatron corresponding to an integrated luminosity
of 9.45/fb. The searches are conducted for Higgs bosons that are produced in
association with a W or Z boson, have masses in the range 90-150 GeV/c^2, and
decay into bb pairs. An excess of data is present that is inconsistent with the
background prediction at the level of 2.5 standard deviations (the most
significant local excess is 2.7 standard deviations).Comment: To be published in Phys. Rev. Lett (v2 contains minor updates based
on comments from PRL
Search for Second-Generation Scalar Leptoquarks in Collisions at =1.96 TeV
Results on a search for pair production of second generation scalar
leptoquark in collisions at =1.96 TeV are reported. The
data analyzed were collected by the CDF detector during the 2002-2003 Tevatron
Run II and correspond to an integrated luminosity of 198 pb. Leptoquarks
(LQ) are sought through their decay into (charged) leptons and quarks, with
final state signatures represented by two muons and jets and one muon, large
transverse missing energy and jets. We observe no evidence for production
and derive 95% C.L. upper limits on the production cross sections as well
as lower limits on their mass as a function of , where is the
branching fraction for .Comment: 9 pages (3 author list) 5 figure
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