基于随机游走的图嵌入研究综述

近年来,图嵌入已经成为图神经网络领域研究的热点。图嵌入作为图任务分析的一种重要手段,将图的高维非欧信息编码到低维向量空间中,从而提升下游任务的性能和效率。为了及时掌握当前基于随机游走的图嵌入方法的研究现状,通过归纳与整理,对现有的经典模型进行介绍与分类,主要分为基于经典随机游走的模型和基于属性游走的模型;然后对每一种模型解决的问题、算法思想、模型策略、优缺点和应用场景进行了详细的归纳与分析,并在几种常见的数据集上评估了部分模型的性能。通过研究发现,当前的基于随机游走的图嵌入亟待解决四个方面的问题：属性选择、可扩展性、嵌入维度选择和可解释性,针对这些问题,图嵌入需要建立一致的理论框架,为后面的研究提供可参考的标准。     

Password guessers under a microscope: an in-depth analysis to inform deployments

Password guessers are instrumental for assessing the strength of passwords. Despite their diversity and abundance, comparisons between password guessers are limited to simple success rates. Thus, little is known on how password guessers can best be combined with or complement each other. To extend analyses beyond success rates, we devise an analytical framework to compare the types of passwords that guessers generate. Using our framework, we show that different guessers often produce dissimilar passwords, even when trained on the same data. We leverage this result to show that combinations of computationally cheap guessers are as effective in guessing passwords as computationally intensive guessers, but more efficient. Our framework can be used to identify combinations of guessers that will best complement each other. To improve the success rate of any guesser, we also show how an effective training dataset can be identified for a given target password dataset, even when the target dataset is hashed. Our insights allow us to provide a concrete set of practical recommendations for password checking to effectively and efficiently measure password strength.

     

Forward Light Cuts: A Scalable Approach to Real‐Time Global Illumination

We present Forward Light Cuts, a novel approach to real‐time global illumination using forward rendering techniques. We focus on unshadowed diffuse interactions for the first indirect light bounce in the context of large models such as the complex scenes usually encountered in CAD application scenarios. Our approach efficiently generates and uses a multiscale radiance cache by exploiting the geometry‐specific stages of the graphics pipeline, namely the tessellator unit and the geometry shader To do so, we assimilate virtual point lights to the scene's triangles and design a stochastic decimation process chained with a partitioning strategy that accounts for both close‐by strong light reflections, and distant regions from which numerous virtual point lights collectively contribute strongly to the end pixel. Our probabilistic solution is supported by a mathematical analysis and a number of experiments covering a wide range of application scenarios. As a result, our algorithm requires no precomputation of any kind, is compatible with dynamic view points, lighting condition, geometry and materials, and scales to tens of millions of polygons on current graphics hardware.     

Understanding the gap between software process practices and actual practice in very small companies

This paper reports on a grounded theory to study into software developers’ use of software development processes in actual practice in the specific context of very small companies. This study was conducted in three very small software product companies located in Ecuador. The data collection was based on semi-structured qualitative interviews with software project managers, focus group with software developers and was supplemented by the literature and document studies. We interviewed two types of participants (managers and developers), so as to ensure that we elicited a holistic perspective of how they approached the software development process in actual practice. The goal was to study what practices are actually used and their opinion and attitude toward the potential adopting of an international standard (ISO/IEC 29110) specifically designed for very small companies. With the collected data, we performed an analysis utilizing grounded theory coding techniques, as this methodology promotes the focus on uncovering the real concerns of the participants. This study highlighted three areas of concern: customer, software product and development tasks coordination and tracking. The findings in this study give an insight toward the work products as they relate to software development process practices in very small companies and the important factors that must be considered to assist project success.     

Complete carbon analysis of sulfur‐containing mixtures using postcolumn reaction and flame ionization detection

Quantitative analysis of complex mixtures containing hundreds‐to‐thousands of organic compounds rich in heteroatoms, including oxygen, sulfur, and nitrogen, is a major challenge in the fuel, food, and chemical industries. In this work, a two‐stage (oxidation and methanation) catalytic process in a 3‐D–printed metal microreactor was evaluated for its capability to convert sulfur‐containing organic compounds to methane. The microreactor was inserted into a gas chromatograph between the capillary column and flame ionization detector. Catalytic conversion of all sulfur‐containing analytes to methane enabled carbon quantification without calibration, by the method identified as “quantitative carbon detection” or QCD. Quantification of tetrahydrothiophene, dimethyl sulfoxide, diethyl sulfide, and thiophene indicated complete conversion to methane at 450°C. Long‐term performance of a commercial microreactor was evaluated for 2000 consecutive injections of sulfur‐containing organic analytes. The sulfur processing capacity of the microreactor was identified experimentally, after which reduced conversion to methane was observed. © 2017 American Institute of Chemical Engineers AIChE J, 63: 5438–5444, 2017     

Experimental model of transient cerebral circulatory disorders by way of embolization of cerebral arteries with fresh blood clots

A total of 85 experimental animals received through the blood flux of the carotid arteries clots of autogenic blood of 1 hour age. A histomorphological study after 40 minutes following an embolism there were revealed clots in the cerebral arteries in 13 out of 14 animals. After 1.5 hours in 1 of 17, and after 24 hours in none of the 10 animals. Directly following the administration of clots in all the 20 animals of this series, there were symptoms of focal brain lesions: hemipareses, ptosis and myosis, a "trot around circles", etc. In all 20 animals there was a complete regress of the symptom at different times (from 10 min to 18 hours). In all cases there was an increased amount of lactic acid in the cerebral blood outflow while subsequently was reduced, correlating with the time of clot lysis. The morphological control did not depict brain infarctions. It is assumed that the reason of brain dysfunctions is an obturation by blood clots of cerebral arteries, while their normalization is due to a spontaneous lysis of the embols which obturated the cerebral arteries.     

Participation of bdellovibrios in sewage self-purification processes

The participation of bacterial parasites belonging to the genus Bdellovibrio in the processes of sewage self-purification was studied in refineries of Pushchino. The lytic activity of Bdellovibrio resulting in a decrease of the number of heterotrophic Gram-negative bacteria and E. coli in sewage was found to depend on the temperature factor influencing the intensity of interaction between the parasite and the host bacterium. The maximal p/h (parasite/host) index was found at the water temperature of 26 degrees C and the minimal one at 19 degrees C. Sewage purified at 26 degrees C and transferred to a precipitation tank contained 800 cells of E. coli in 1 ml while that purified at 19 degrees C contained 4000 cells in 1 ml. The number of interacting organisms varied in sewage which was typical of the "parasite-host" relations. Therefore, Bdellovibrio should be involved in the self-purification of sewage from the intestinal microflora at 26 degrees C; to a lesser extent, at 23.5 degrees C; and not at all, at 19 degrees C.     

Mechanisms of histamine stimulated secretion in rabbit ileal mucosa

Histamine is present in high concentrations in the intestine and we investigated the possibility that it might have a role here in intestinal transport. When added to the basal side of rabbit ileal mucosa in vitro histamine (10(-4)M) induced a short-lived increase in electrical potential difference and short circuit current. It inhibited net chloride absorption but did not influence sodium transport. Alkali secretion, measured by a pH stat technique, was inhibited, suggesting that bicarbonate secretion was reduced. Both the electrical and ion flux responses to histamine were blocked by the H1 receptor blocker diphenhydramine, but not by the H2 receptor blocker cimetidine. The presence of specific H1 histamine receptors was further supported by shifts in the dose-response curve to histamine by four different concentrations of diphenhydramine. Calculation of a pA2 value from these "Schild' plots provided a figure of 7.85, which is similar to that for H1 receptors in other tissues. Aminoguanidine, a histaminase blocker, had no electrical effects alone but shifted the histamine dose response curve to the left. These studies indicate that histamine inhibits chloride absorption and alkali secretion, possibly by influencing a chloride/bicarbonate exchange process, through specific mucosal H1 receptors. Enhancement of histamine effects by a histaminase inhibitor suggests that histaminases are present in the intestinal mucosa and supports the possibility of a role for endogenous histamine in influencing ion transport. The observations indicate a mechanism by which absorption might be impaired in diseases in which histamine is liberated locally in the intestine.     

The infrared spectra of saturated fatty acids with even number of carbon atoms from caproic,C6 (Hexanoic), to stearic,C18 (Octadecanoic), and of their methyl and ethyl esters

Summary Infrared spectra from 1 to 12 microns have been obtained for 7 of the homologous series of monobasic, straight-chain, saturated fatty acids of even carbon atom content from C₆ to C₁₈ and of their methyl and ethyl esters. Infrared data are presented as plots of the percentage transmission against the wavelength in microns on a linear wavelength scale for each compound, and the exact wavelength positions of maxima of the 11 most prominent bands are tabulated. Correlations of each of these bands with molecular structure are given. Methods for distinguishing the acids from the esters and of differentiating an ethyl ester from a methyl ester by observation of infrared spectra are described. An explanation, supported by earlier work with deuterium-substituted compounds, is given to account for the nonappearance, in the spectra of the fatty acids of any absorption attributable to either the free O—H group or the bonded O—H... O group. Evidence has been accumulated which indicates an association of some sort of the esters and that this association probably involves the carbonyl and the methyl groups. Data are presented to show which of the bands in the infrared spectra do and which do not follow Beer’s law. Presented before the 1950 Fall Meeting of the American Oil Chemists’ Society, San Francisco, California. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.