212 research outputs found
Modeling the broadband emission of Fermi/LAT GRB 090902B
GRB 090902B, detected by Fermi Large Array Telescope (Fermi/LAT), shows
extend high-energy emission (>100 MeV) up to 10^3 s after the burst, which
decays with time in a power-law as t^{-1.5}. It has been also observed by
several follow-up low-energy instruments, including an early optical detection
around 5000 s after the burst. The optical emission at early time decays faster
than t^{-1.6}, which has been suspected to originate from the reverse shock. We
here explore the models that can possibly explain the the broadband afterglow
emission of GRB 090902B. We find that the reverse shock model for the early
optical emission would overpredict the radio afterglow flux that is
inconsistent with observations. A partially radiative blast wave model, which
though is able to produce a sufficiently steep decay slope, can not explain the
broadband data of GRB 090902B. The two-component jet model, which consists of a
narrow and bright jet component in the core and a surrounding wider and less
energetic jet component, is shown to be able to explain the broadband afterglow
data, including the LAT high-energy data after ~50 s and low-energy (radio,
optical and X-ray) afterglow data. The early-time high-energy emission detected
by LAT before ~50 s is likely due to internal origin as that of the sub-MeV
emission. The highest energy (33 GeV) photon of GRB090902B detected at 80 s can
be marginally accommodated within the forward shock emission under the
optimistic condition that electrons are accelerated by the Bohm diffusive
shock.Comment: Accepted for publication in ApJ (minor changes, references updated),
11 pages (emulateapj style), 4 figure
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Molecular identification of Trichinella spiralis nudix hydrolase and its induced protective immunity against trichinellosis in BALB/c mice
Background: Nudix hydrolases (Nd) is a widespread superfamily, which is found in all classes of organism, hydrolyse a wide range of organic pyrophosphates and has a ‘housecleaning’ function. The previous study showed that Trichinella spiralis Nd (TsNd) bound to intestinal epithelial cells (IECs), and the vaccination of mice with T7 phage-displayed TsNd polypeptides produced protective immunity. The aim of this study was to clone, express and identify the full-length TsNd and to investigate its immune protection against T. spiralis infection. Methods: The full-length cDNA sequence of TsNd gene encoding a 46 kDa protein from T. spiralis intestinal infective larvae (IIL) was cloned and identified. The antigenicity of rTsNd was analyzed by Western blot. Transcription and expression of TsNd at T. spiralis different stages were observed by RT-PCR and IFT. The levels of the specific total IgG, IgG1 and IgG2a antibodies to rTsNd were determined by ELISA. The immune protection of rTsNd against T. spiralis infection was investigated. Results: Sequence and phylogenetic analysis revealed that TsNd had a nudix motif located at 226-244aa, which had high homology and the closest evolutionary status with T. pseudospiralis. The rTsNd was obtained after expression and purification. Western blot analysis showed that anti-rTsNd serum recognized the native TsNd protein in crude antigens of muscle larvae (ML), IIL, adult worms (AW) and newborn larvae (NBL), and ES antigens of ML. Transcription and expression of TsNd gene was observed in all developmental stages of T. spiralis (ML, IIL, AW and NBL), with high level expression in IIL. An immunolocalization analysis identified TsNd in the cuticle, stichocytes and reproductive organs of the parasite. Following immunization, anti-rTsNd IgG levels were increased, and the levels of IgG1 were more significantly higher than that of IgG2a. After a challenge infection with T. spiralis, mice immunized with the rTsNd displayed a 57.7% reduction in adult worms and a 56.9% reduction in muscle larval burden. Conclusions: TsNd induced a partial protective immunity in mice and could be considered as a novel candidate vaccine antigen against trichinellosis
Capacitive coupling study of the HERD SCD prototype: preliminary results
The Silicon Charge Detector (SCD) is a subdetector of the High Energy Cosmic
Radiation Detection payload. The dynamic range of the silicon microstrip
detector can be extended by the capacitive coupling effect, which is related to
the interstrip capacitance and the coupling capacitance. A detector prototype
with several sets of parameters was designed and tested in the ion beams at the
CERN Super Proton Synchrotron. The capacitive coupling fractions with readout
strip and floating strip incidences were studied using the beam test data and
SPICE simulation
Label-free quantitative proteomic analysis of molting-related proteins of Trichinella spiralis intestinal infective larvae
International audienceAbstractMolting is a key step for body-size expansion and environmental adaptation of parasitic nematodes, and it is extremely important for Trichinella spiralis growth and development, but the molting mechanism is not fully understood. In this work, label-free LC–MS/MS was used to determine the proteome differences between T. spiralis muscle larvae (ML) at the encapsulated stage and intestinal infective larvae (IIL) at the molting stage. The results showed that a total of 2885 T. spiralis proteins were identified, 323 of which were differentially expressed. These proteins were involved in cuticle structural elements, regulation of cuticle synthesis, remodeling and degradation, and hormonal regulation of molting. These differential proteins were also involved in diverse intracellular pathways, such as fatty acid biosynthesis, arachidonic acid metabolism, and mucin type O-glycan biosynthesis. qPCR results showed that five T. spiralis genes (cuticle collagen 14, putative DOMON domain-containing protein, glutamine synthetase, cathepsin F and NADP-dependent isocitrate dehydrogenase) had significantly higher transcriptional levels in 10 h IIL than ML (P < 0.05), which were similar to their protein expression levels, suggesting that they might be T. spiralis molting-related genes. Identification and characterization of T. spiralis molting-related proteins will be helpful for developing vaccines and new drugs against the early enteral stage of T. spiralis
Protective immunity against Trichinella spiralis infection induced by TsNd vaccine in mice
BACKGROUND: We have previously reported that Trichinella spiralis Nudix hydrolase (TsNd) bound to intestinal epithelial cells (IECs), and vaccination of mice with recombinant TsNd protein (rTsNd) produced a partial protective immunity. The aim of this study was to investigate the immune protection induced by TsNd DNA vaccine. METHODS: The full-length cDNA sequence of TsNd gene was cloned into pcDNA3.1 and used to immunize BALB/c mice by intramuscular injection. Transcription and expression of TsNd were detected by RT-PCR and IFT. The levels of specific IgA, IgG, IgG1 and IgG2a, and cytokines were assayed by ELISA at weeks 0, 6 and 8 post-immunization. The immune protection of TsNd DNA vaccine against challenge infection was investigated. RESULTS: Immunization of mice with TsNd DNA elicited a systemic Th1/Th2 immune response and a local mucosal IgA response. The in vitro transcription and expression of TsNd gene was observed at all developmental stages of T. spiralis (ML, IIL, AW and NBL). Anti-rTsNd IgG levels were increased after immunization and levels of IgG1 were obviously higher than that of IgG2a. Intestinal specific IgA levels of immunized mice were significantly higher than those of vector and PBS control mice. Cytokine profiling also showed a significant increase in Th1 (IFN-γ, IL-2) and Th2 (IL-4, 10) responses in splenocytes of immunized mice on stimulation with rTsNd. Vaccination of mice with pcDNA3.1-TsNd displayed a 40.44% reduction in adult worms and a 53.9% reduction in larval burden. CONCLUSIONS: TsNd DNA induced a mixed Th1/Th2 immune response and partial protection against T. spiralis infection in mice
Experimental evidence for Berry curvature multipoles in antiferromagnets
Berry curvature multipoles appearing in topological quantum materials have
recently attracted much attention. Their presence can manifest in novel
phenomena, such as nonlinear anomalous Hall effects (NLAHE). The notion of
Berry curvature multipoles extends our understanding of Berry curvature effects
on the material properties. Hence, research on this subject is of fundamental
importance and may also enable future applications in energy harvesting and
high-frequency technology. It was shown that a Berry curvature dipole can give
rise to a 2nd order NLAHE in materials of low crystalline symmetry. Here, we
demonstrate a fundamentally new mechanism for Berry curvature multipoles in
antiferromagnets that are supported by the underlying magnetic symmetries.
Carrying out electric transport measurements on the kagome antiferromagnet
FeSn, we observe a 3rd order NLAHE, which appears as a transverse voltage
response at the 3rd harmonic frequency when a longitudinal a.c. current drive
is applied. Interestingly, this NLAHE is strongest at and above room
temperature. We combine these measurements with a scaling law analysis, a
symmetry analysis, model calculations, first-principle calculations, and
magnetic Monte-Carlo simulations to show that the observed NLAHE is induced by
a Berry curvature quadrupole appearing in the spin-canted state of FeSn. At a
practical level, our study establishes NLAHE as a sensitive probe of
antiferromagnetic phase transitions in other materials, such as moir\'e
superlattices, two-dimensional van der Waal magnets, and quantum spin liquid
candidates, that remain poorly understood to date. More broadly, Berry
curvature multipole effects are predicted to exist for 90 magnetic point
groups. Hence, our work opens a new research area to study a variety of
topological magnetic materials through nonlinear measurement protocols
Sex and age differences in chronic postoperative pain among patients undergoing thoracic surgery: a retrospective cohort study
BackgroundThe effect of sex and age on chronic post-thoracic surgical pain (CPTP) at rest and with activity remains unclear. The main purpose of this study was to investigate the relationship between the incidence of chronic postoperative pain (at rest and with activity) and sex/age differences.MethodsThis was a single-center retrospective study that included adult patients who had undergone elective thoracic surgery. Patients were divided into two groups based on sex. Demographic and perioperative data were collected, including age, sex, education level, Body Mass Index (BMI), American Society of Anesthesiologists (ASA) physical status, and medical history (hypertension, diabetes mellitus). Chronic postoperative pain data were collected by telephone follow-up.ResultsAmong the 3,159 patients enrolled, 1,762 were male, and 1,397 were female. After creating a matched-pairs cohort, 1,856 patients were analyzed. The incidence of CPTP at rest was 14.9% among males and 17.8% among females (p = 0.090). The incidence of CPTP with activity was 28.4% among males and 35.0% among females (p = 0.002). We analyzed three different models after propensity matching to validate the stability of the prediction model between sex and CPTP, and female sex was a significant predictor of CPTP with activity 3 months after surgery. Further analysis showed that females in the 45-55-year-old age group were more prone to develop CPTP.ConclusionFemales have a higher incidence of chronic postoperative pain with activity after thoracic surgery. Females in the 45-55-year-old age group are more prone to develop CPTP than females in other age groups
Dual-comb spectroscopy over 100km open-air path
Satellite-based greenhouse gases (GHG) sensing technologies play a critical
role in the study of global carbon emissions and climate change. However, none
of the existing satellite-based GHG sensing technologies can achieve the
measurement of broad bandwidth, high temporal-spatial resolution, and high
sensitivity at the same time. Recently, dual-comb spectroscopy (DCS) has been
proposed as a superior candidate technology for GHG sensing because it can
measure broadband spectra with high temporal-spatial resolution and high
sensitivity. The main barrier to DCS's display on satellites is its short
measurement distance in open air achieved thus far. Prior research has not been
able to implement DCS over 20 km of open-air path. Here, by developing a
bistatic setup using time-frequency dissemination and high-power optical
frequency combs, we have implemented DCS over a 113 km turbulent horizontal
open-air path. Our experiment successfully measured GHG with 7 nm spectral
bandwidth and a 10 kHz frequency and achieved a CO2 sensing precision of <2 ppm
in 5 minutes and <0.6 ppm in 36 minutes. Our results represent a significant
step towards advancing the implementation of DCS as a satellite-based
technology and improving technologies for GHG monitoringComment: 24 pages, 6 figure
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