171 research outputs found
Gamma-ray burst engines may have no memory
A sizeable fraction of gamma-ray burst (GRB) time profiles consist of a
temporal sequence of pulses. The nature of this stochastic process carries
information on how GRB inner engines work. The so-called interpulse time
defines the interval between adjacent pulses, excluding the long quiescence
periods during which the signal drops to the background level. It was found by
many authors in the past that interpulse times are lognormally distributed, at
variance with the exponential case that is expected for a memoryless process.
We investigated whether the simple hypothesis of a temporally uncorrelated
sequence of pulses is really to be rejected, as a lognormal distribution
necessarily implies. We selected and analysed a number of multi--peaked
CGRO/BATSE GRBs and simulated similar time profiles, with the crucial
difference that we assumed exponentially distributed interpulse times, as is
expected for a memoryless stationary Poisson process. We then identified peaks
in both data sets using a novel peak search algorithm, which is more efficient
than others used in the past. We independently confirmed that the observed
interpulse time distribution is approximately lognormal. However, we found the
same results on the simulated profiles, in spite of the intrinsic exponential
distribution. Although intrinsic lognormality cannot be ruled out, this shows
that intrinsic interpulse time distribution in real data could still be
exponential, while the observed lognormal could be ascribed to the low
efficiency of peak search algorithms at short values combined with the
limitations of a bin-integrated profile. Our result suggests that GRB engines
may emit pulses after the fashion of nuclear radioactive decay, that is, as a
memoryless process.Comment: 4 pages, 3 figures, accepted in A&
A common stochastic process rules gamma-ray burst prompt emission and X-ray flares
Prompt gamma-ray and early X-ray afterglow emission in gamma-ray bursts
(GRBs) are characterized by a bursty behavior and are often interspersed with
long quiescent times. There is compelling evidence that X-ray flares are linked
to prompt gamma-rays. However, the physical mechanism that leads to the complex
temporal distribution of gamma-ray pulses and X-ray flares is not understood.
Here we show that the waiting time distribution (WTD) of pulses and flares
exhibits a power-law tail extending over 4 decades with index ~2 and can be the
manifestation of a common time-dependent Poisson process. This result is robust
and is obtained on different catalogs. Surprisingly, GRBs with many (>=8)
gamma-ray pulses are very unlikely to be accompanied by X-ray flares after the
end of the prompt emission (3.1 sigma Gaussian confidence). These results are
consistent with a simple interpretation: an hyperaccreting disk breaks up into
one or a few groups of fragments, each of which is independently accreted with
the same probability per unit time. Prompt gamma-rays and late X-ray flares are
nothing but different fragments being accreted at the beginning and at the end,
respectively, following the very same stochastic process and likely the same
mechanism.Comment: 11 pages, 7 figures, accepted by Ap
Controlled-release oxycodone and pregabalin in the treatment of neuropathic pain: results of a multicenter Italian study
Abstract
AIMS:
The aim of our study was to compare the efficacy, safety, and quality of life of combination therapy with controlled-release (CR) oxycodone plus pregabalin versus monotherapy with either CR oxycodone or pregabalin in patients with neuropathic pain.
MATERIALS AND METHODS:
Patients with moderate to severe neuropathic pain, despite the use of various pharmacologic treatments prior to study entry, were enrolled (n = 409) and treated with CR oxycodone plus pregabalin (n = 169), CR oxycodone (n = 106), and pregabalin (n = 134). Pain intensity was rated on an 11-point numerical rating scale (NRS).
RESULTS:
The combination of CR oxycodone plus pregabalin and CR oxycodone monotherapy were both more effective for alleviating neuropathic pain than pregabalin monotherapy (reduction in NRS value: 80, 76, and 46%, respectively; p </= 0.003). Significantly greater improvements from baseline in quality of life were reported with combination therapy than with monotherapy (p = 0.0009). At the end of treatment, the majority (91.2%) of patients receiving CR oxycodone plus pregabalin found that the treatment had been 'effective' or 'very effective'. Combination therapy also allowed a dose reduction of both agents (22% for CR oxycodone and 51% for pregabalin) compared with the dosages of the respective monotherapies. Combination therapy had a superior safety profile compared with pregabalin monotherapy.
CONCLUSIONS:
The combination of CR oxycodone plus pregabalin may represent a valuable addition to the existing pharmacotherapy for neuropathic pain and warrants further investigation
The PLASMONX Project for advanced beam physics experiments
The Project PLASMONX is well progressing into its
design phase and has entered as well its second phase of
procurements for main components. The project foresees
the installation at LNF of a Ti:Sa laser system (peak
power > 170 TW), synchronized to the high brightness
electron beam produced by the SPARC photo-injector.
The advancement of the procurement of such a laser
system is reported, as well as the construction plans of a
new building at LNF to host a dedicated laboratory for
high intensity photon beam experiments (High Intensity
Laser Laboratory). Several experiments are foreseen
using this complex facility, mainly in the high gradient
plasma acceleration field and in the field of mono-
chromatic ultra-fast X-ray pulse generation via Thomson
back-scattering. Detailed numerical simulations have
been carried out to study the generation of tightly focused
electron bunches to collide with laser pulses in the
Thomson source: results on the emitted spectra of X-rays
are presented
Epidermolysa bullosa in Danish Hereford calves is caused by a deletion in LAMC2 gene
BACKGROUND
Heritable forms of epidermolysis bullosa (EB) constitute a heterogeneous group of skin disorders of genetic aetiology that are characterised by skin and mucous membrane blistering and ulceration in response to even minor trauma. Here we report the occurrence of EB in three Danish Hereford cattle from one herd.
RESULTS
Two of the animals were necropsied and showed oral mucosal blistering, skin ulcerations and partly loss of horn on the claws. Lesions were histologically characterized by subepidermal blisters and ulcers. Analysis of the family tree indicated that inbreeding and the transmission of a single recessive mutation from a common ancestor could be causative. We performed whole genome sequencing of one affected calf and searched all coding DNA variants. Thereby, we detected a homozygous 2.4 kb deletion encompassing the first exon of the LAMC2 gene, encoding for laminin gamma 2 protein. This loss of function mutation completely removes the start codon of this gene and is therefore predicted to be completely disruptive. The deletion co-segregates with the EB phenotype in the family and absent in normal cattle of various breeds. Verifying the homozygous private variants present in candidate genes allowed us to quickly identify the causative mutation and contribute to the final diagnosis of junctional EB in Hereford cattle.
CONCLUSIONS
Our investigation confirms the known role of laminin gamma 2 in EB aetiology and shows the importance of whole genome sequencing in the analysis of rare diseases in livestock
A COL7A1 Mutation Causes Dystrophic Epidermolysis Bullosa in Rotes Höhenvieh Cattle
We identified a congenital mechanobullous skin disorder in six calves on a single farm of an endangered German cattle breed in 2010. The condition presented as a large loss of skin distal to the fetlocks and at the mucosa of the muzzle. All affected calves were euthanized on humane grounds due to the severity, extent and progression of the skin and oral lesions. Examination of skin samples under light microscopy revealed detachment of the epidermis from the dermis at the level of the dermo epidermal junction, leading to the diagnosis of a subepidermal bullous dermatosis such as epidermolysis bullosa. The pedigree was consistent with monogenic autosomal recessive inheritance. We localized the causative mutation to an 18 Mb interval on chromosome 22 by homozygosity mapping. The COL7A1 gene encoding collagen type VII alpha 1 is located within this interval and COL7A1 mutations have been shown to cause inherited dystrophic epidermolysis bullosa (DEB) in humans. A SNP in the bovine COL7A1 exon 49 (c.4756C>T) was perfectly associated with the observed disease. The homozygous mutant T/T genotype was exclusively present in affected calves and their parents were heterozygous C/T confirming the assumed recessive mode of inheritance. All known cases and genotyped carriers were related to a single cow, which is supposed to be the founder animal. The mutant T allele was absent in 63 animals from 24 cattle breeds. The identified mutation causes a premature stop codon which leads to a truncated protein representing a complete loss of COL7A1 function (p.R1586*). We thus have identified a candidate causative mutation for this genetic disease using only three cases to unravel its molecular basis. Selection against this mutation can now be used to eliminate the mutant allele from the Rotes Höhenvieh breed
Multi-Messenger Astronomy with Extremely Large Telescopes
The field of time-domain astrophysics has entered the era of Multi-messenger
Astronomy (MMA). One key science goal for the next decade (and beyond) will be
to characterize gravitational wave (GW) and neutrino sources using the next
generation of Extremely Large Telescopes (ELTs). These studies will have a
broad impact across astrophysics, informing our knowledge of the production and
enrichment history of the heaviest chemical elements, constrain the dense
matter equation of state, provide independent constraints on cosmology,
increase our understanding of particle acceleration in shocks and jets, and
study the lives of black holes in the universe. Future GW detectors will
greatly improve their sensitivity during the coming decade, as will
near-infrared telescopes capable of independently finding kilonovae from
neutron star mergers. However, the electromagnetic counterparts to
high-frequency (LIGO/Virgo band) GW sources will be distant and faint and thus
demand ELT capabilities for characterization. ELTs will be important and
necessary contributors to an advanced and complete multi-messenger network.Comment: White paper submitted to the Astro2020 Decadal Surve
A Mildly Relativistic Outflow from the Energetic, Fast-rising Blue Optical Transient CSS161010 in a Dwarf Galaxy
We present X-ray and radio observations of the Fast Blue Optical Transient CRTS-CSS161010 J045834-081803 (CSS161010 hereafter) at t = 69-531 days. CSS161010 shows luminous X-ray (L x ∼ 5 × 1039 erg s-1) and radio (L ν ∼ 1029 erg s-1 Hz-1) emission. The radio emission peaked at ∼100 days post-transient explosion and rapidly decayed. We interpret these observations in the context of synchrotron emission from an expanding blast wave. CSS161010 launched a mildly relativistic outflow with velocity Γβc ≥ 0.55c at ∼100 days. This is faster than the non-relativistic AT 2018cow (Γβc ∼ 0.1c) and closer to ZTF18abvkwla (Γβc ≥ 0.3c at 63 days). The inferred initial kinetic energy of CSS161010 (E k ⪆ 1051 erg) is comparable to that of long gamma-ray bursts, but the ejecta mass that is coupled to the mildly relativistic outflow is significantly larger (∼ 0.01-0.1 M⊙). This is consistent with the lack of observed γ-rays. The luminous X-rays were produced by a different emission component to the synchrotron radio emission. CSS161010 is located at ∼150 Mpc in a dwarf galaxy with stellar mass M * ∼ 107 M o&dot; and specific star formation rate sSFR ∼ 0.3 Gyr-1. This mass is among the lowest inferred for host galaxies of explosive transients from massive stars. Our observations of CSS161010 are consistent with an engine-driven aspherical explosion from a rare evolutionary path of a H-rich stellar progenitor, but we cannot rule out a stellar tidal disruption event on a centrally located intermediate-mass black hole. Regardless of the physical mechanism, CSS161010 establishes the existence of a new class of rare (rate < 0.4% of the local core-collapse supernova rate) H-rich transients that can launch mildly relativistic outflows.</p
A survey of current practices by the British Oculoplastic Surgery Society (BOPSS) and recommendations for delivering a sustainable multidisciplinary approach to thyroid eye disease in the United Kingdom
The Royal College of Physicians (RCP) and Thyroid Eye Disease Amsterdam Declaration Implementation Group (TEAMeD-5) have the common goal of improving access to high quality care for thyroid eye disease (TED). The TEAMeD-5 programme recommends all patients with moderate-to-severe TED should have access to multidisciplinary clinics (MDT) with combined Ophthalmology and Endocrinology expertise
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