911 research outputs found
Empirical multi-wavelength prediction method for very high energy gamma-ray emitting BL Lacs
Aim: We have collected the most complete multi-wavelength () dataset of very high energy (VHE) -ray emitting (TeV) BL
Lacs, which are the most numerous extragalactic VHE sources. Using significant
correlations between different bands, we aim to identify the best TeV BL Lac
candidates that can be discovered by the current and next generation of imaging
air Cherenkov telescopes.
Methods: We formed five datasets from lower energy data, i.e. radio,
mid-infrared, optical, X-rays, and GeV -ray, and five VHE -ray
datasets to perform a correlation study between different bands and to
construct the prediction method. The low energy datasets were averaged for
individual sources, while the VHE -ray data were divided into subsets
according to the flux state of the source. We then looked for significant
correlations and determined their best-fit parameters. Using the best-fit
parameters we predicted the level of VHE -ray flux for a sample of 182
BL Lacs, which have not been detected at TeV energies. We identified the most
promising TeV BL Lac candidates based on the predicted VHE -ray flux
for each source.
Results: We found 14 significant correlations between radio, mid-infrared,
optical, -ray, and VHE -ray bands. The correlation between
optical and VHE -ray luminosity is established for the first time. We
attribute this to the more complete sample and more accurate handling of host
galaxy flux in our work. We found nine BL Lac candidates whose predicted VHE
-ray flux is high enough for detection in less than 25 hours with
current imaging air Cherenkov telescopes.Comment: 10 pages, 2 figures, 4 Table
Enhancement of broiler performance and immune response by Echinacea purpurea supplemented in diet
The objective of the present study was to compare short and long term application of Echinacea purpurea root powder on growth performance and immunity response of broiler chicks. Three replicate trials involving a total of 600 day-old Ross chicks were used in this study. In each trial, a total of 200 chicks were randomly allocated into 5 groups. Each group consisted of 4 pens with 10 chicks in each pen. The birds in group A received control mash diet during the experiment, but those in groups B and C were given control diet supplemented with 0.1% (w/w) and 0.5% (w/w) E. purpurea root powder, respectively. The chicks in groups D and E received control diet supplemented with 0.1% (w/w) and 0.5% (w/w) E. purpurea root powder, respectively, just for one week and fed control diet afterwards. The results showed that E. purpurea consumption for six weeks changed the total counts of white blood cells (WBCs), number of lymphocytes and heterophils, feed conversation ratio, and antibody titers against newcastle and avian influenza diseases (p < 0.05). In conclusion, this result suggests that feeding E. purpurea, particularly for long time, may improve feed conversion, change blood cells number and enhance immunity response in broilers.Key words: Echinacea purpurea, broilers, feed conversion, immunity response
Quasi-periodicities of BL Lac Objects
We review the reports of possible year-long quasi-periodicities of BL Lac
objects in the -ray and optical bands, and present a homogeneous time
analysis of the light curves of PKS2155304, PG1553+113, and BL Lac. Based on
results from a survey covering the entire Fermi -ray sky we have
estimated the fraction of possible quasi-periodic BL Lac objects. We compared
the cyclical behaviour in BL Lac objects with that derived from the search of
possible optical periodicities in quasars, and find that at z1 the
cosmic density of quasi-periodic BL Lac objects is larger than that of
quasi-periodic quasars. If the BL Lac quasi-periodicities were due to a
supermassive binary black hole (SBBH) scenario, there could be a tension with
the upper limits on the gravitational wave background measured by the pulsar
timing array. The argument clearly indicates the difficulties of generally
associating quasi-periodicities of BL Lac objects with SBBHs.Comment: In publication on A&A, 6 pages, 4 figure (11 plots). Minor
corrections adde
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Cellular antiseizure mechanisms of everolimus in pediatric tuberous sclerosis complex, cortical dysplasia, and non-mTOR-mediated etiologies.
The present study was designed to examine the potential cellular antiseizure mechanisms of everolimus, a mechanistic target of rapamycin (mTOR) pathway blocker, in pediatric epilepsy cases. Cortical tissue samples obtained from pediatric patients (n = 11, ages 0.67-6.75 years) undergoing surgical resections for the treatment of their pharmacoresistant epilepsy were examined electrophysiologically in ex vivo slices. The cohort included mTOR-mediated pathologies (tuberous sclerosis complex [TSC] and severe cortical dysplasia [CD]) as well as non-mTOR-mediated pathologies (tumor and perinatal infarct). Bath application of everolimus (2 μm) had practically no effect on spontaneous inhibitory postsynaptic activity. In contrast, long-term application of everolimus reduced spontaneous excitatory postsynaptic activity, burst discharges induced by blockade of γ-aminobutyric acid A (GABAA) receptors, and epileptiform activity generated by 4-aminopyridine, a K+ channel blocker. The antiseizure effects were more pronounced in TSC and CD cases, whereas in non-mTOR-mediated pathologies, the effects were subtle at best. These results support further clinical trials of everolimus in mTOR pathway-mediated pathologies and emphasize that the effects require sustained exposure over time
Predictors of seizure outcomes in children with tuberous sclerosis complex and intractable epilepsy undergoing resective epilepsy surgery: an individual participant data meta-analysis.
ObjectiveTo perform a systematic review and individual participant data meta-analysis to identify preoperative factors associated with a good seizure outcome in children with Tuberous Sclerosis Complex undergoing resective epilepsy surgery.Data sourcesElectronic databases (MEDLINE, EMBASE, CINAHL and Web of Science), archives of major epilepsy and neurosurgery meetings, and bibliographies of relevant articles, with no language or date restrictions.Study selectionWe included case-control or cohort studies of consecutive participants undergoing resective epilepsy surgery that reported seizure outcomes. We performed title and abstract and full text screening independently and in duplicate. We resolved disagreements through discussion.Data extractionOne author performed data extraction which was verified by a second author using predefined data fields including study quality assessment using a risk of bias instrument we developed. We recorded all preoperative factors that may plausibly predict seizure outcomes.Data synthesisTo identify predictors of a good seizure outcome (i.e. Engel Class I or II) we used logistic regression adjusting for length of follow-up for each preoperative variable.ResultsOf 9863 citations, 20 articles reporting on 181 participants were eligible. Good seizure outcomes were observed in 126 (69%) participants (Engel Class I: 102(56%); Engel class II: 24(13%)). In univariable analyses, absence of generalized seizure semiology (OR = 3.1, 95%CI = 1.2-8.2, p = 0.022), no or mild developmental delay (OR = 7.3, 95%CI = 2.1-24.7, p = 0.001), unifocal ictal scalp electroencephalographic (EEG) abnormality (OR = 3.2, 95%CI = 1.4-7.6, p = 0.008) and EEG/Magnetic resonance imaging concordance (OR = 4.9, 95%CI = 1.8-13.5, p = 0.002) were associated with a good postoperative seizure outcome.ConclusionsSmall retrospective cohort studies are inherently prone to bias, some of which are overcome using individual participant data. The best available evidence suggests four preoperative factors predictive of good seizure outcomes following resective epilepsy surgery. Large long-term prospective multicenter observational studies are required to further evaluate the risk factors identified in this review
A significant hardening and rising shape detected in the MeV/GeV nuFnu spectrum from the recently-discovered very-high-energy blazar S4 0954+65 during the bright optical flare in 2015 February
We report on Fermi Large Area Telescope (LAT) and multi-wavelength results on
the recently-discovered very-high-energy (VHE, 100 GeV) blazar S4 0954+65
() during an exceptionally bright optical flare in 2015 February.
During the time period (2015 February, 13/14, or MJD 57067) when the MAGIC
telescope detected VHE -ray emission from the source, the Fermi-LAT
data indicated a significant spectral hardening at GeV energies, with a
power-law photon index of ---compared with the 3FGL value
(averaged over four years of observation) of . In contrast,
Swift/XRT data showed a softening of the X-ray spectrum, with a photon index of
(compared with averaged during the flare from
MJD 57066 to 57077), possibly indicating a modest contribution of synchrotron
photons by the highest-energy electrons superposed on the inverse Compton
component. Fitting of the quasi-simultaneous ( day) broadband spectrum with
a one-zone synchrotron plus inverse-Compton model revealed that GeV/TeV
emission could be produced by inverse-Compton scattering of external photons
from the dust torus. We emphasize that a flaring blazar showing high flux of
photons cm s ( 100 MeV) and a
hard spectral index of detected by Fermi-LAT on daily
time scales is a promising target for TeV follow-up by ground-based Cherenkov
telescopes to discover high-redshift blazars, investigate their temporal
variability and spectral features in the VHE band, and also constrain the
intensity of the extragalactic background light.Comment: 15 pages, 3 figures, 2 tables. Accepted by PAS
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