223 research outputs found
Fourth Generation Leptons and Muon
We consider the contributions to from fourth generation heavy
neutral and charged leptons, and , at the one-loop level.
Diagrammatically, there are two types of contributions: boson-boson-, and
--boson in the loop diagram. In general, the effect from is
suppressed by off-diagonal lepton mixing matrix elements. For , we consider
flavor changing neutral couplings arising from various New Physics models,
which are stringently constrained by . We assess how the
existence of a fourth generation would affect these New Physics models.Comment: Minor changes, with references update
Speech Dereverberation Based on Integrated Deep and Ensemble Learning Algorithm
Reverberation, which is generally caused by sound reflections from walls,
ceilings, and floors, can result in severe performance degradation of acoustic
applications. Due to a complicated combination of attenuation and time-delay
effects, the reverberation property is difficult to characterize, and it
remains a challenging task to effectively retrieve the anechoic speech signals
from reverberation ones. In the present study, we proposed a novel integrated
deep and ensemble learning algorithm (IDEA) for speech dereverberation. The
IDEA consists of offline and online phases. In the offline phase, we train
multiple dereverberation models, each aiming to precisely dereverb speech
signals in a particular acoustic environment; then a unified fusion function is
estimated that aims to integrate the information of multiple dereverberation
models. In the online phase, an input utterance is first processed by each of
the dereverberation models. The outputs of all models are integrated
accordingly to generate the final anechoic signal. We evaluated the IDEA on
designed acoustic environments, including both matched and mismatched
conditions of the training and testing data. Experimental results confirm that
the proposed IDEA outperforms single deep-neural-network-based dereverberation
model with the same model architecture and training data
An Envelope Disrupted by a Quadrupolar Outflow in the Pre-Planetary Nebula IRAS19475+3119
IRAS 19475+3119 is a quadrupolar pre-planetary nebula (PPN), with two bipolar
lobes, one in the east-west (E-W) direction and one in the southeast-northwest
(SE-NW) direction. We have observed it in CO J=2-1 with the Submillimeter Array
at ~ 1" resolution. The E-W bipolar lobe is known to trace a bipolar outflow
and it is detected at high velocity. The SE-NW bipolar lobe appears at low
velocity, and could trace a bipolar outflow moving in the plane of the sky. Two
compact clumps are seen at low velocity around the common waist of the two
bipolar lobes, spatially coincident with the two emission peaks in the NIR,
tracing dense envelope material. They are found to trace the two
limb-brightened edges of a slowly expanding torus-like circumstellar envelope
produced in the late AGB phase. This torus-like envelope originally could be
either a torus or a spherical shell, and it appears as it is now because of the
two pairs of cavities along the two bipolar lobes. Thus, the envelope appears
to be disrupted by the two bipolar outflows in the PPN phase.Comment: 23 pages, 8 figure
Antioxidant Sol-Gel Improves Cutaneous Wound Healing in Streptozotocin-Induced Diabetic Rats
We examined the effects of vitamin C in Pluronic F127 on diabetic wound healing. Full-thickness excision skin wounds were made in normal and diabetic Wistar rats to evaluate the effect of saline, saline plus vitamin C (antioxidant sol), Pluronic F127, or Pluronic F127 plus vitamin C (antioxidant sol-gel). The rate of wound contraction, the levels of epidermal and dermal maturation, collagen synthesis, and apoptosis production in the wound tissue were determined. In vitro data showed that after 6 hours of air exposure, the order of the scavenging abilities for HOCl, H2O2, and O2 - was antioxidant sol-gel > antioxidant saline > Pluronic F127 = saline. After 7 and 14 days of wound injury, the antioxidant sol-gel improved wound healing significantly by accelerated epidermal and dermal maturation, an increase in collagen content, and a decrease in apoptosis formation. However, the wounds of all treatments healed mostly at 3 weeks. Vitamin C in Pluronic F127 hastened cutaneous wound healing by its antioxidant and antiapoptotic mechanisms through a good drug delivery system. This study showed that Pluronic F127 plus vitamin C could potentially be employed as a novel wound-healing enhancer
Comparison of the mismatch-specific endonuclease method and denaturing high-performance liquid chromatography for the identification of HBB gene mutations
<p>Abstract</p> <p>Background</p> <p>Beta-thalassemia is a common autosomal recessive hereditary disease in the Meditertanean, Asia and African areas. Over 600 mutations have been described in the beta-globin (<it>HBB</it>), of which more than 200 are associated with a beta-thalassemia phenotype.</p> <p>Results</p> <p>We used two highly-specific mutation screening methods, mismatch-specific endonuclease and denaturing high-performance liquid chromatography, to identify mutations in the <it>HBB </it>gene. The sensitivity and specificity of these two methods were compared. We successfully distinguished mutations in the <it>HBB </it>gene by the mismatch-specific endonuclease method without need for further assay. This technique had 100% sensitivity and specificity for the study sample.</p> <p>Conclusion</p> <p>Compared to the DHPLC approach, the mismatch-specific endonuclease method allows mutational screening of a large number of samples because of its speed, sensitivity and adaptability to semi-automated systems. These findings demonstrate the feasibility of using the mismatch-specific endonuclease method as a tool for mutation screening.</p
Differential effects of neurotrophins and schwann cell-derived signals on neuronal survival/growth and synaptogenesis
Recent studies have shown that the survival of mammalian motoneurons in vitro is promoted by neurotrophins (NTs) and cAMP. There is also evidence that neurotrophins enhance transmitter release.Wethus investigated whether these agents also promote synaptogenesis. Cultured Xenopus spinal cord neurons were treated with a mixture of BDNF, glia-derived neurotrophic factor, NT-3, and NT-4, in addition to forskolin and IBMX or the cell-permeant form of cAMP, to elevate the cAMP level. The outgrowth and survival of neurons were dramatically increased by this trophic stimulation. However, when these neurons were cocultured with muscle cells, the trophic agents resulted in a failure of synaptogenesis. Specifically, the induction ofAChreceptor (AChR) clustering in cultured muscle cells was inhibited at nerve–muscle contacts, in sharp contrast to control, untreated cocultures. Because AChR clustering induced by agrin or growth factor-coated beads in muscle cells was unaffected by trophic stimulation, its effect on synaptogenesis is presynaptic in origin. In the control, agrin was deposited along the neurite and at nerve–muscle contacts. This was significantly downregulated in cultures treated with trophic stimuli. Reverse transcriptase-PCR analyses showed that this decrease in agrin deposition was caused by an inhibition of agrin synthesis by trophic stimuli. Both agrin synthesis and induction of AChR clustering were restored under trophic stimulation when Schwann cell-conditioned medium was introduced. These results suggest that trophic stimulation maintains spinal neurons in the growth state, and Schwann cell-derived factors allow them to switch to the synaptogenic state
The K2-ESPRINT Project III: A Close-in Super-Earth around a Metal-rich Mid-M Dwarf
We validate a planet on a close-in orbit
( days) around K2-28 (EPIC 206318379), a metal-rich
M4-type dwarf in the Campaign 3 field of the K2 mission. Our follow-up
observations included multi-band transit observations from the optical to the
near infrared, low-resolution spectroscopy, and high-resolution adaptive-optics
(AO) imaging. We perform a global fit to all the observed transits using a
Gaussian process-based method and show that the transit depths in all passbands
adopted for the ground-based transit follow-ups () are within of the K2 value. Based on a model of
the background stellar population and the absence of nearby sources in our AO
imaging, we estimate the probability that a background eclipsing binary could
cause a false positive to be . We also show that K2-28
cannot have a physically associated companion of stellar type later than M4,
based on the measurement of almost identical transit depths in multiple
passbands. There is a low probability for a M4 dwarf companion (), but even if this were the case, the size of K2-28b
falls within the planetary regime. K2-28b has the same radius (within
) and experiences a similar irradiation from its host star as the
well-studied GJ~1214b. Given the relative brightness of K2-28 in the near
infrared ( mag and mag) and relatively deep
transit (), a comparison between the atmospheric properties of these
two planets with future observations would be especially interesting.Comment: 11 pages, 9 figures, accepted to Ap
Isolation, Culture and Characterization of Hirsutella sinensis Mycelium from Caterpillar Fungus Fruiting Body
The caterpillar fungus Ophiocordyceps sinensis (previously called Cordyceps sinensis) has been used for centuries in Asia as a tonic to improve health and longevity. Recent studies show that O. sinensis produces a wide range of biological effects on cells, laboratory animals and humans, including anti-fatigue, anti-infection, anti-inflammatory, antioxidant, and anti-tumor activities. In view of the rarity of O. sinensis fruiting bodies in nature, cultivation of its anamorph mycelium represents a useful alternative for large-scale production. However, O. sinensis fruiting bodies harvested in nature harbor several fungal contaminants, a phenomenon that led to the isolation and characterization of a large number of incorrect mycelium strains. We report here the isolation of a mycelium from a fruiting body of O. sinensis and we identify the isolate as O. sinensis’ anamorph (also called Hirsutella sinensis) based on multi-locus sequence typing of several fungal genes (ITS, nrSSU, nrLSU, RPB1, RPB2, MCM7, β-tubulin, TEF-1α, and ATP6). The main characteristics of the isolated mycelium, including its optimal growth at low temperature (16°C) and its biochemical composition, are similar to that of O. sinensis fruiting bodies, indicating that the mycelium strain characterized here may be used as a substitute for the rare and expensive O. sinensis fruiting bodies found in nature
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