160 research outputs found
Superpartner spectrum of minimal gaugino-gauge mediation
We evaluate the sparticle mass spectrum in the minimal four-dimensional
construction that interpolates between gaugino and ordinary gauge mediation at
the weak scale. We find that even in the hybrid case -- when the messenger
scale is comparable to the mass of the additional gauge particles -- both the
right-handed as well as the left-handed sleptons are lighter than the bino in
the low-scale mediation regime. This implies a chain of lepton production and,
consequently, striking signatures that may be probed at the LHC already in the
near future.Comment: 8 pages, 3 figures; V2: refs and a few comments added; V3 title
change
Combining Anomaly and Z' Mediation of Supersymmetry Breaking
We propose a scenario in which the supersymmetry breaking effect mediated by
an additional U(1)' is comparable with that of anomaly mediation. We argue that
such a scenario can be naturally realized in a large class of models. Combining
anomaly with Z' mediation allows us to solve the tachyonic slepton problem of
the former and avoid significant fine tuning in the latter. We focus on an
NMSSM-like scenario where U(1)' gauge invariance is used to forbid a tree-level
mu term, and present concrete models, which admit successful dynamical
electroweak symmetry breaking. Gaugino masses are somewhat lighter than the
scalar masses, and the third generation squarks are lighter than the first two.
In the specific class of models under consideration, the gluino is light since
it only receives a contribution from 2-loop anomaly mediation, and it decays
dominantly into third generation quarks. Gluino production leads to distinct
LHC signals and prospects of early discovery. In addition, there is a
relatively light Z', with mass in the range of several TeV. Discovering and
studying its properties can reveal important clues about the underlying model.Comment: Minor changes: references added, typos corrected, journal versio
Body composition and body fat distribution are related to cardiac autonomic control in non-alcoholic fatty liver disease patients
BACKGROUND/OBJECTIVES: Heart rate recovery (HRR), a cardiac autonomic control marker, was shown to be related to body composition (BC), yet this was not tested in non-alcoholic fatty liver disease (NAFLD) patients. The aim of this study was to determine if, and to what extent, markers of BC and body fat (BF) distribution are related to cardiac autonomic control in NAFLD patients. SUBJECTS/METHODS: BC was assessed with dual-energy X-ray absorptiometry in 28 NAFLD patients (19 men, 51±13 years, and 9 women, 47±13 years). BF depots ratios were calculated to assess BF distribution. Subjectsâ HRR was recorded 1 (HRR1) and 2 min (HRR2) immediately after a maximum graded exercise test.
RESULTS: BC and BF distribution were related to HRR; particularly weight, trunk BF and trunk BF-to-appendicular BF ratio showed a negative relation with HRR1 (r 1â4 0.613, r 1â4 0.597 and r 1â4 0.547, respectively, Po0.01) and HRR2 (r 1â4 0.484, r 1â4 0.446, Po0.05, and r 1â4 0.590, Po0.01, respectively). Age seems to be related to both HRR1 and HRR2 except when controlled for BF distribution. The preferred model in multiple regression should include trunk BF-to-appendicular BF ratio and BF to predict HRR1 (r2 1â4 0.549; Po0.05), and trunk BF-to-appendicular BF ratio alone to predict HRR2 (r2 1â4 0.430; Po0.001).
CONCLUSIONS: BC and BF distribution were related to HRR in NAFLD patients. Trunk BF-to-appendicular BF ratio was the best independent predictor of HRR and therefore may be best related to cardiovascular increased risk, and possibly act as a mediator in age-related cardiac autonomic control variation.info:eu-repo/semantics/publishedVersio
Testing the gaugino AMSB model at the Tevatron via slepton pair production
Gaugino AMSB models-- wherein scalar and trilinear soft SUSY breaking terms
are suppressed at the GUT scale while gaugino masses adopt the AMSB form--
yield a characteristic SUSY particle mass spectrum with light sleptons along
with a nearly degenerate wino-like lightest neutralino and quasi-stable
chargino. The left- sleptons and sneutrinos can be pair produced at
sufficiently high rates to yield observable signals at the Fermilab Tevatron.
We calculate the rate for isolated single and dilepton plus missing energy
signals, along with the presence of one or two highly ionizing chargino tracks.
We find that Tevatron experiments should be able to probe gravitino masses into
the ~55 TeV range for inoAMSB models, which corresponds to a reach in gluino
mass of over 1100 GeV.Comment: 14 pages including 6 .eps figure
Alternative Splicing of sept9a and sept9b in Zebrafish Produces Multiple mRNA Transcripts Expressed Throughout Development
Background: Septins are involved in a number of cellular processes including cytokinesis and organization of the cytoskeleton. Alterations in human septin-9 (SEPT9) levels have been linked to multiple cancers, whereas mutations in SEPT9 cause the episodic neuropathy, hereditary neuralgic amyotrophy (HNA). Despite its important function in human health, the in vivo role of SEPT9 is unknown. Methodology/Principal Findings: Here we utilize zebrafish to study the role of SEPT9 in early development. We show that zebrafish possess two genes, sept9a and sept9b that, like humans, express multiple transcripts. Knockdown or overexpression of sept9a transcripts results in specific developmental alterations including circulation defects and aberrant epidermal development. Conclusions/Significance: Our work demonstrates that sept9 plays an important role in zebrafish development, an
Kinetically-Enhanced Anomaly Mediation
We investigate a modification of anomaly-mediated supersymmetry breaking
(AMSB) with an exotic U(1)_x gauge sector that can solve the tachyonic slepton
problem of minimal AMSB scenarios. The new U(1)_x multiplet is assumed to
couple directly to the source of supersymmetry breaking, but only indirectly to
the minimal supersymmetric Standard Model (MSSM) through kinetic mixing with
hypercharge. If the MSSM sector is also sequestered from the source of
supersymmetry breaking, the contributions to the MSSM soft terms come from both
AMSB and the U(1)_x kinetic coupling. We find that this arrangement can give
rise to a flavour-universal, phenomenologically viable, and distinctive
spectrum of MSSM superpartners. We also investigate the prospects for discovery
and the most likely signatures of this scenario at the Large Hadron Collider
(LHC).Comment: 29 pages, 10 figures; Added references, corrected ctau plot in Fig.
4, same general conclusion
The Interplay Between GUT and Flavour Symmetries in a Pati-Salam x S4 Model
Both Grand Unified symmetries and discrete flavour symmetries are appealing
ways to describe apparent structures in the gauge and flavour sectors of the
Standard Model. Both symmetries put constraints on the high energy behaviour of
the theory. This can give rise to unexpected interplay when building models
that possess both symmetries. We investigate on the possibility to combine a
Pati-Salam model with the discrete flavour symmetry that gives rise to
quark-lepton complementarity. Under appropriate assumptions at the GUT scale,
the model reproduces fermion masses and mixings both in the quark and in the
lepton sectors. We show that in particular the Higgs sector and the running
Yukawa couplings are strongly affected by the combined constraints of the Grand
Unified and family symmetries. This in turn reduces the phenomenologically
viable parameter space, with high energy mass scales confined to a small region
and some parameters in the neutrino sector slightly unnatural. In the allowed
regions, we can reproduce the quark masses and the CKM matrix. In the lepton
sector, we reproduce the charged lepton masses, including bottom-tau
unification and the Georgi-Jarlskog relation as well as the two known angles of
the PMNS matrix. The neutrino mass spectrum can present a normal or an inverse
hierarchy, and only allowing the neutrino parameters to spread into a range of
values between and , with .
Finally, our model suggests that the reactor mixing angle is close to its
current experimental bound.Comment: 62 pages, 4 figures; references added, version accepted for
publication in JHE
Transplantation of Photoreceptor and Total Neural Retina Preserves Cone Function in P23H Rhodopsin Transgenic Rat
Background: Transplantation as a therapeutic strategy for inherited retinal degeneration has been historically viewed to restore vision as a method by replacing the lost retinal cells and attempting to reconstruct the neural circuitry with stem cells, progenitor cells and mature neural retinal cells. Methods and Findings: We present evidence for an alternative strategy aimed at preventing the secondary loss of cones, the most crucial photoreceptors for vision, by transplanting normal photoreceptors cells into the eye of the P23H rat, a model of dominant retinitis pigmentosa. We carried out transplantation of photoreceptors or total neural retina in 3-monthold P23H rats and evaluated the function and cell counts 6 months after surgery. In both groups, cone loss was significantly reduced (10%) in the transplanted eyes where the cone outer segments were found to be considerably longer. This morphological effect correlated with maintenance of the visual function of cones as scored by photopic ERG recording, but more precisely with an increase in the photopic b-wave amplitudes by 100 % and 78 % for photoreceptor transplantation and whole retinal transplantation respectively. Conclusions: We demonstrate here that the transplanted tissue prevents the loss of cone function, which is furthe
Retinal repair by transplantation of photoreceptor precursors
Photoreceptor loss causes irreversible blindness in many retinal diseases. Repair of such damage by cell transplantation is one of the most feasible types of central nervous system repair; photoreceptor degeneration initially leaves the inner retinal circuitry intact and new photoreceptors need only make single, short synaptic connections to contribute to the retinotopic map. So far, brain- and retina-derived stem cells transplanted into adult retina have shown little evidence of being able to integrate into the outer nuclear layer and differentiate into new photoreceptors(1-4). Furthermore, there has been no demonstration that transplanted cells form functional synaptic connections with other neurons in the recipient retina or restore visual function. This might be because the mature mammalian retina lacks the ability to accept and incorporate stem cells or to promote photoreceptor differentiation. We hypothesized that committed progenitor or precursor cells at later ontogenetic stages might have a higher probability of success upon transplantation. Here we show that donor cells can integrate into the adult or degenerating retina if they are taken from the developing retina at a time coincident with the peak of rod genesis(5). These transplanted cells integrate, differentiate into rod photoreceptors, form synaptic connections and improve visual function. Furthermore, we use genetically tagged postmitotic rod precursors expressing the transcription factor Nrl (ref. 6) ( neural retina leucine zipper) to show that successfully integrated rod photoreceptors are derived only from immature post-mitotic rod precursors and not from proliferating progenitor or stem cells. These findings define the ontogenetic stage of donor cells for successful rod photoreceptor transplantation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62596/1/nature05161.pd
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