Discovery of an extra hard spectral component in the high-energy afterglow emission of GRB 130427A

The extended high-energy gamma-ray (>100 MeV) emission occurred after the prompt gamma-ray bursts (GRBs) is usually characterized by a single power-law spectrum, which has been explained as the afterglow synchrotron radiation. The afterglow inverse-Compton emission has long been predicted to be able to produce a high-energy component as well, but previous observations have not revealed such a signature clearly, probably due to the small number of >10 GeV photons even for the brightest GRBs known so far. In this Letter, we report on the Fermi Large Area Telescope (LAT) observations of the >100 MeV emission from the very bright and nearby GRB 130427A. We characterize the time-resolved spectra of the GeV emission from the GRB onset to the afterglow phase. By performing time-resolved spectral fits of GRB 130427A, we found a strong evidence of an extra hard spectral component that exists in the extended high-energy emission of this GRB. We argue that this hard component may arise from the afterglow inverse Compton emission.Comment: 5 pages, 2 figures, 2 tables, ApJL, in pres

Spectral fluctuations in the interacting boson model

The energy dependence of the spectral fluctuations in the interacting boson model (IBM) and its connections to the mean-field structures have been analyzed through adopting two statistical measures, the nearest neighbor level spacing distribution $P(S)$ measuring the chaoticity (regularity) in energy spectra and the $\Delta_3(L)$ statistics of Dyson and Metha measuring the spectral rigidity. Specifically, the statistical results as functions of the energy cutoff have been worked out for different dynamical situations including the U(5)-SU(3) and SU(3)-O(6) transitions as well as those near the AW arc of regularity. It is found that most of the changes in spectral fluctuations are triggered near the stationary points of the classical potential especially for the cases in the deformed region of the IBM phase diagram. The results thus justify the stationary point effects from the point of view of statistics. In addition, the approximate degeneracies in the $2^+$ spectrum on the AW arc is also revealed from the statistical calculations

Numerical simulation analysis of multi-physical coupling field with abrasive flow precision polishing variable-aperture tube

In the fields of aerospace, precision machinery and energy, there are variable-diameter tubes for many key components. Abrasive flow polishing technology is an effective precision polishing technology for finishing the workpiece with an internal cavity structure. This technology can improve the quality of part finishing, reduce stress concentration, and reduce the surface roughness of the workpiece, and ultimately can improve the performance of the workpiece. In this paper, variable-aperture tube is taken as the research object, and the characteristics of abrasive flow in the multi-physics coupling field are studied by numerical simulation, and the collision removal effect between the abrasive particle and the wall surface is analyzed. We also discussed the control law of the abrasive grain flow processing quality and provided theoretical guidance for abrasive grain flow polishing of this type of part

U-rank: Utility-oriented Learning to Rank with Implicit Feedback

Learning to rank with implicit feedback is one of the most important tasks in many real-world information systems where the objective is some specific utility, e.g., clicks and revenue. However, we point out that existing methods based on probabilistic ranking principle do not necessarily achieve the highest utility. To this end, we propose a novel ranking framework called U-rank that directly optimizes the expected utility of the ranking list. With a position-aware deep click-through rate prediction model, we address the attention bias considering both query-level and item-level features. Due to the item-specific attention bias modeling, the optimization for expected utility corresponds to a maximum weight matching on the item-position bipartite graph. We base the optimization of this objective in an efficient Lambdaloss framework, which is supported by both theoretical and empirical analysis. We conduct extensive experiments for both web search and recommender systems over three benchmark datasets and two proprietary datasets, where the performance gain of U-rank over state-of-the-arts is demonstrated. Moreover, our proposed U-rank has been deployed on a large-scale commercial recommender and a large improvement over the production baseline has been observed in an online A/B testing

A randomized controlled trial to compare the effect of peanuts and almonds on the cardio-metabolic and inflammatory parameters in patients with Type 2 Diabetes Mellitus

A low carbohydrate diet (LCD), with some staple food being replaced with nuts, has been shown to reduce weight, improve blood glucose, and regulate blood lipid in patients with type 2 diabetes mellitus (T2DM). These nuts include tree nuts and ground nuts. Tree nut consumption is associated with improved cardio-vascular and inflammatory parameters. However, the consumption of tree nuts is difficult to promote in patients with diabetes because of their high cost. As the main ground nut, peanuts contain a large number of beneficial nutrients, are widely planted, and are affordable for most patients. However, whether peanuts and tree nuts in combination with LCD have similar benefits in patients with T2DM remains unknown; although almonds are the most consumed and studied tree nut. This study sought to compare the effect of peanuts and almonds, incorporated into a LCD, on cardio-metabolic and inflammatory measures in patients with T2DM. Of the 32 T2DM patients that were recruited, 17 were randomly allocated to the Peanut group (n = 17) and 15 to the Almond group (n = 15) in a parallel design. The patients consumed a LCD with part of the starchy staple food being replaced with peanuts (Peanut group) or almonds (Almond group). The follow-up duration was three months. The indicators for glycemic control, other cardio-metabolic, and inflammatory parameters were collected and compared between the two groups. Twenty-five patients completed the study. There were no significant differences in the self-reported dietary compliance between the two groups. Compared with the baseline, the fasting blood glucose (FBG) and postprandial 2-h blood glucose (PPG) decreased in both the Peanut and Almond groups (p < 0.05). After the intervention, no statistically significant differences were found between the Peanut group and the Almond group with respect to the FBG and PPG levels. A decrease in the glycated hemoglobin A1c (HbA1c) level from the baseline in the Almond group was found (p < 0.05). However, no significant difference was found between the two groups with respect to the HbA1c level at the third month. The peanut and almond consumption did not increase the body mass index (BMI) and had no effect on the blood lipid profile or interleukin-6 (IL-6).In conclusion, incorporated into a LCD, almonds and peanuts have a similar effect on improving fasting and postprandial blood glucose among patients with T2DM. However, more studies are required to fully establish the effect of almond on the improvement of HbA1c

The effect of low-carbohydrate diet on glycemic control in patients with Type 2 Diabetes Mellitus

Objective: In China, a low-fat diet (LFD) is mainly recommended to help improve blood glucose levels in patients with type 2 diabetes mellitus (T2DM). However, a low-carbohydrate diet (LCD) has been shown to be effective in improving blood glucose levels in America and England. A few studies, primarily randomized controlled trials, have been reported in China as well. Method: Firstly, we designed two ‘six-point formula’ methods, which met the requirements of LCD and LFD, respectively. Fifty-six T2DM patients were recruited and randomly allocated to the LCD group (n = 28) and the LFD group (n = 28). The LCD group received education about LCD’s six-point formula, while the LFD group received education about LFD’s six-point formula. The follow-up time was three months. The indicators for glycemic control and other metabolic parameters were collected and compared between the two groups. Results: Forty-nine patients completed the study. The proportions of calories from three macronutrients the patients consumed met the requirements of LCD and LFD. Compared to the LFD group, there was a greater decrease in HbA1c level in the LCD group (−0.63% vs. −0.31%, p < 0.05). The dosages of insulin and fasting blood glucoses (FBG) in the third month were lower than those at baseline in both groups. Compared with baseline values, body mass index (BMI) and total cholesterol (TC) in the LCD group were significantly reduced in the third month (p < 0.05); however, there were no statistically significant differences in the LFD group. Conclusions: LCD can improve blood glucose more than LFD in Chinese patients with T2DM. It can also regulate blood lipid, reduce BMI, and decrease insulin dose in patients with T2DM. In addition, the six-point formula is feasible, easily operable, and a practical educational diet for Chinese patients with T2DM