Modeling Multi-wavelength Pulse Profiles of Millisecond Pulsar PSR B1821-24

PSR B1821$-$24 is a solitary millisecond pulsar (MSP) which radiates multi-wavelength pulsed photons. It has complex radio, X-ray and $\gamma$-ray pulse profiles with distinct peak phase-separations that challenge the traditional caustic emission models. Using the single-pole annular gap model with suitable magnetic inclination angle ($\alpha=40^\circ$) and viewing angle ($\zeta=75^\circ$), we managed to reproduce its pulse profiles of three wavebands. It is found that the middle radio peak is originated from the core gap region at high altitudes, and the other two radio peaks are originated from the annular gap region at relatively low altitudes. Two peaks of both X-ray and $\gamma$-ray wavebands are fundamentally originated from annular gap region, while the $\gamma$-ray emission generated from the core gap region contributes somewhat to the first $\gamma$-ray peak. Precisely reproducing the multi-wavelength pulse profiles of PSR B1821$-$24 enables us to understand emission regions of distinct wavebands and justify pulsar emission models.Comment: Accepted for publication in Ap

Mission Overview and Initial Observation Results of the X-Ray Pulsar Navigation-I Satellite

The newly launched X-ray pulsar navigation-I (XPNAV-1) is an experimental satellite of China that is designed for X-ray pulsar observation. This paper presents the initial observation results and aims to recover the Crab pulsar’s pulse profile to verify the X-ray instrument’s capability of observing pulsars in space. With the grazing-incidence focusing type instrument working at the soft X-ray band (0.5–10 keV), up to 162 segments of observations of the Crab pulsar are fulfilled, and more than 5 million X-ray events are recorded. Arrival times of photons are corrected to the solar system barycentre, and the 33 ms pulse period is sought out for Crab. Epoch folding of all the corrected photon times generates the refined pulse profile of Crab. The characteristic two-peak profile proves that the Crab pulsar has been clearly seen, so that the conclusion is made that XPNAV-1’s goal of being capable of observing pulsars is achieved

Composition Relation between Nonlinear Bloch Waves and Gap Solitons in Periodic Fractional Systems

Evolution of beams in nonlinear optical media with a fractional-order diffraction is currently attracting a growing interest. We address the existence of linear and nonlinear Bloch waves in fractional systems with a periodic potential. Under a defocusing nonlinearity, nonlinear Bloch waves at the centers or edges of the first Brillouin zone bifurcate from the corresponding linear Bloch modes at different band edges. They can be constructed by directly copying a fundamental gap soliton (in one lattice site) or alternatively copying it and its mirror image to infinite lattice channels. The localized truncated-Bloch-wave solitons bridging nonlinear Bloch waves and gap solitons are also revealed. We thus prove that fundamental gap solitons can be used as unit cells to build nonlinear Bloch waves or truncated-Bloch-wave solitons, even in fractional configurations. Our results provide helpful hints for understanding the dynamics of localized and delocalized nonlinear modes and the relation between them in periodic fractional systems with an optical nonlinearity

Leaf choice in black-and-white snub-nosed monkeys Rhinopithecus bieti is related to the physical and chemical properties of leaves

To understand the effects of the chemical and physical properties of plant leaves on food choice in Rhinopithecus bieti, we collected mature leaves of nine food and five non-food plant species at the southernmost part of the species’s range. Chemical properties such as fat, ash, crude protein (CP), total phenolics (TP), and fiber content including neutral detergent fiber (NDF), acid detergent fiber (ADF), lignin, celluloses and hemicelluloses, and physical toughness were measured. R. bieti tended to choose leaves with lower fiber content, higher ash, a higher ratio of CP/ADF, and lower toughness. No difference was found for fat, crude protein, total phenolics, hemicelluloses and lignin between food and non-food leaves. Even though the ratio of CP/ADF is generally regarded as a good indicator for colobine food choice, the difference in the ratio of CP/ADF between food and non-food leaves was only the result of differences in ADF. Since positive correlations were found between ADF and toughness from all leaves (both food and non-food species), and toughness of leaves was likely easier for R. bieti to sense than fiber content via mastication, the toughness of leaves may function as a predictor of food choice in this species [Current Zoology 56 (6): 643–649, 2010]

ITC-LM: A Smart Iteration-Termination Criterion Based Live Virtual Machine Migration

Part 2: Session 2: Cloud Resource ManagementInternational audienceLive migration of virtual machines (VMs) plays an important role in grids, clouds and datacenters, and has become the cornerstone of resource management in virtualized systems. The efficiency of live migration depends on the downtime, total migration time and total transferred data. However, while migrating a memory-intensive VM, XEN/KVM often do many useless iterations of memory copy in order to reach expected downtime which can never be reached, leading to a great deal of useless data transferring and insufferable total migration time. It consumes mass of network bandwidth and CPU resource when transferring memory from one to another node. Hence, a critical task is to determine the optimal time to terminate the copy iteration for live migration. In this paper, we propose a smart iteration-termination criterion based live migration which is termed as ITC-LM, to self adaptively control when to terminate iteration. We have implemented ITC-LM into KVM/QEMU. The improvement is significant, especially when migrate a memory-intensive VM. The experimental results show that, our approach can decrease 50.33% of total transferred data on average without impairing migration downtime

Engender Persistent Organic Room-Temperature Phosphorescence by Trace Ingredient Incorporation

The trace impurities in pure organic phosphors were always ignored because the ultra-low content impurities were considered to hardly affect the luminescent properties. Evidences from corresponding reports and research have shown that impurities may greatly affect room temperature phosphorescence (RTP) in some crystalline compounds. To date, very few literatures have clearly study the role of impurities in RTP because of the difficulty in the separation and structure identification of impurities. Also no reports have focused on utilizing trace impurities to form new strategies for efficient RTP. For the first time, an impurity was isolated from 1-(4-bromophenyl)-1H-imidazole (1BBI) and structural identified, which was proved to be the key to RTP in 1BBI crystal. Neither purified impurity nor 1BBI matrix shown any detectable RTP. The impurity could light up the unusual ultralong RTP in matrix even at 0.01 mol% content. Inspired by impurity/matrix phosphorescence, a trace-ingredient-mediated bicomponent strategy was introduced for high phosphorescence quantum yield (QY, up to 74.2%) and extralong lifetime (up to 430 ms).Research Highlights of this work are including1. The study of impurities in organic luminescent materials, including phosphorescent materials, is rarely reported due to the great difficulty of separation, purification and structure characterization. This work not only separated, purified and structure identified the trace impurity in the system but also confirmed the fact that the impurity engenders the RTP. And the corresponding mechanism was proposed as well.2. Inspired by the role of impurities in RTP, this work proposed an effective strategy for the design and preparation of persistent organic RTP based on active ingredient incorporation. Seven compounds were screened out to conduct the bicomponent RTP system and achieved bright RTP with high QY (up to 74.2%) and extra-long lifetime (up to 430 ms)) RTP with tunable colors.3. Combining the dual emission of blue fluorescence and yellow phosphorescence, a bicomponent system achieved a bright white-light emission, which shows its outstanding application potential. The design concept and strategy of this work supplies an efficient approach to develop RTP by simply mixing the matrix with a trace amount of active ingredients. And the trace-ingredient-mediated bicomponent system is preferred for its high efficiency, color-tunable, low cost and easy to prepare properties, which will make important sense for facilely developing organic persistent RTP materials. This work will not only lead to a new understanding of persistent organic RTP but also develop a facile and effective strategy for RTP afterglow materials.</p

Fundamental solitons in the nonlinear fractional Schrödinger equation with a

We address the existence and stability of fundamental solitons in a $\mathcal{PT}$ -symmetric Gaussian potential embedded into a material with fractional effects. Fundamental solitary waves with low power both in defocusing and focusing medium originate from the same eigenmode, and the smaller the Lévy index, the narrower the width of solitons. The linear stability analysis of fundamental solitons has been carried out in fractional dimension. $\mathcal{PT}$ -symmetric solitons are completely stable for a moderate Lévy index and gain/loss coefficient in a wide existence region