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

Gerir a diversidade: contributos da aprendizagem cooperativa para a construção de salas de aula inclusivas

The action-research we have held at the primary education, in a school placed near the town of Tomar, in 2009-2010, under the master's degree in Special Education, was the starting point for writing this article. The research had as main objective to promote the successful learning of a heterogeneous group of students, where a child considered with longstanding special educational needs is included – diagnosis of galactosaemia and cognitive impairment. Starting from the educational context of a particular classroom of 2nd and 3rd grades, where we were working as special education teacher, we had created an inclusive learning environment for each student in the class. Through effective collaboration between fellow teachers, we generated changes in methodologies, breaking with some traditional practices in the classroom, when regular teachers and special education are in the same learning space. By a systematic implementation of cooperative learning strategies among students, and applying qualitative data gathering techniques of research, before and after the intervention – interview, naturalistic observation, sociometry and documental research –, we have increased the quality and quantity of learning and promoted another way of ‘looking to’ the difference

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

The Hi-GAL catalogue of dusty filamentary structures in the Galactic plane

The recent data collected by Herschel have confirmed that interstellar structures with a filamentary shape are ubiquitously present in the Milky Way. Filaments are thought to be formed by several physical mechanisms acting from large Galactic scales down to subparsec fractions of molecular clouds, and they might represent a possible link between star formation and the large-scale structure of the Galaxy. In order to study this potential link, a statistically significant sample of filaments spread throughout the Galaxy is required. In this work, we present the first catalogue of 32 059 candidate filaments automatically identified in the Herschel Infrared Galactic plane Survey (Hi-GAL) of the entire Galactic plane. For these objects, we determined morphological (length la and geometrical shape) and physical (average column density NH2 and average temperature T) properties. We identified filaments with a wide range of properties: 2 ≤ la ≤ 100 arcmin, 1020≤NH2≤1023 cm−2 and 10 ≤ T ≤ 35 K. We discuss their association with the Hi-GAL compact sources, finding that the most tenuous (and stable) structures do not host any major condensation. We also assign a distance to ∼18 400 filaments, for which we determine mass, physical size, stability conditions and Galactic distribution. When compared with the spiral arms structure, we find no significant difference between the physical properties of on-arm and inter-arm filaments. We compare our sample with previous studies, finding that our Hi-GAL filament catalogue represents a significant extension in terms of Galactic coverage and sensitivity. This catalogue represents a unique and important tool for future studies devoted to understanding the filament life-cycle