Simple, nondestructive test identifies metals

Rapid, nondestructive test for identifying metals measures the characteristic potential difference produced by galvanic reaction between a reference electrode and the test metal. A drop of water is used as an electrolyte

Trends Prediction Using Social Diffusion Models

The importance of the ability of predict trends in social media has been growing rapidly in the past few years with the growing dominance of social media in our everyday's life. Whereas many works focus on the detection of anomalies in networks, there exist little theoretical work on the prediction of the likelihood of anomalous network pattern to globally spread and become "trends". In this work we present an analytic model the social diffusion dynamics of spreading network patterns. Our proposed method is based on information diffusion models, and is capable of predicting future trends based on the analysis of past social interactions between the community's members. We present an analytic lower bound for the probability that emerging trends would successful spread through the network. We demonstrate our model using two comprehensive social datasets - the "Friends and Family" experiment that was held in MIT for over a year, where the complete activity of 140 users was analyzed, and a financial dataset containing the complete activities of over 1.5 million members of the "eToro" social trading community.Comment: 6 Pages + Appendi

Galactic gamma bays and the origin of cosmic rays

The question of the origin of the cosmic radiation is a fundamental problem in high energy astro physics, this thesis is concerned with one particular aspect of this question namely, whether or not the cosmic ray sources are Galactic or Extragalactic. This problem is Investigated through the results of Galactic Gamma-ray astronomy. The main mechanism for gamma ray production are discussed. The observational results of Galactic Gamma ray astronomy are described. Theories about the Galactic cosmic ray sources and the distribution of these sources are described and related to the resulting distribution of cosmic rays in various propagation models. The distribution of gas in the galaxy is described. Calculations are presented which indicate that the role of Inverse Compton Scattering in producing the observed Galactic Gamma ray intensity is small. The reason for the disagreement of this result with earlier results is analysed. The distribution of cosmic rays in the inner Galaxy (0-10 kpc from the Galactic Centre) is determined from a comparison of the distribution of Gamma ray emissivity and the hydrogen distribution, this Is found to follow the distribution of sources between 6 - 10 kpc. The penetration of dense molecular clouds by cosmic rays is investigated. It is concluded that the uncertainties in the hydrogen distribution do not permit us to rule out an Extragalactic origin, from the inner Galaxy data . The distribution of gamma ray intensity in the Galactic anticentre is modelled on Galactic and Extragalactic theories and the predictions of the Galactic model are found to be in excellent agreement with observation. The cosmic ray distribution is found to be consistent with the origin in Supernovae or their remnants. It is concluded that there is rather strong evidence for the majority of cosmic ray nuclei between 1 and 10 GeV having been produced within the Galaxy

N-heterocyclic germylenes: structural characterisation of some heavy analogues of the ubiquitous N-heterocyclic carbenes

The X-ray crystal structures of three N-heterocyclic germylenes (NHGes) have been elucidated including the previously unknown 1,3-bis(2,6-dimethylphenyl)diazagermol-2-ylidene (1). In addition, the X-ray crystal structures of the previously synthesised 1,3-bis(2,4,6-trimethylphenyl)diazagermol-2-ylidene (2) and 1,3-bis(2,6-diisopropylphenyl)diazagermol-2-ylidene (3) are also reported. The discrete molecular structures of compounds 1 to 3 are comparable, with Ge-N bond lengths in the range 1.835-1.875 Å, while the N-Ge-N bond angles range between 83.6 and 85.2°. Compound 2 was compared to the analogous N-heterocyclic carbene species, 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene (IMes). The major geometrical difference observed, as expected, was the bond angle around the divalent group 14 atom. The N-Ge-N bond angle was 83.6° for compound 2 versus the N-C-N bond angle of 101.4° for IMes. The Sn equivalent of (1), 1,3-bis(2,6-dimethylphenyl)diazastannol-2-ylidene (4), has also been synthesised and its crystal structure is reported here. In order to test their suitability as ligands, compounds 1 to 3 were reacted with a wide range of transition metal complexes. No NHGes containing metal complexes were observed. In all cases the NHGe either degraded or gave no reaction

Identity and Search in Social Networks

Social networks have the surprising property of being "searchable": Ordinary people are capable of directing messages through their network of acquaintances to reach a specific but distant target person in only a few steps. We present a model that offers an explanation of social network searchability in terms of recognizable personal identities: sets of characteristics measured along a number of social dimensions. Our model defines a class of searchable networks and a method for searching them that may be applicable to many network search problems, including the location of data files in peer-to-peer networks, pages on the World Wide Web, and information in distributed databases.Comment: 4 page, 3 figures, revte

Gendered Residential Space

Gay Villages, Gay Ghettos, and other gay and lesbian residential enclaves have all become a standard part of urban space, but who actually lives in these neighborhoods and how does each differ? One obvious variation is gender, particularly as it is traditionally understood. As a population that inherently breaks conventional gender stereotypes, is it possible that gay and lesbian settlement patterns still reinforce gender stereotypes? This paper explores gender in neighborhoods with high lesbian and gay populations and particularly questions what are the factors that lead lesbians to concentrate in certain residential spaces. The research focuses on the Philadelphia neighborhoods of Mount Airy and Washington Square West and serves to better understand gendered space in the larger scheme of urban settlement

CHEM 109: General Chemistry I—A Peer Review of Teaching Project Benchmark Portfolio

This portfolio has been developed for CHEM 109: General Chemistry I. The course is the first of a freshman level two semester sequence in General Chemistry taken by students with majors in a wide variety of technical and scientific disciplines. CHEM 109 is a high enrollment class, with class sizes for individual sections nearing 200 students. The development of this portfolio was conducted with the following objectives: 1. Clearly identify, justify, and codify the major learning objectives for this course, 2. Describe and rationalize the course structure and learning assessment methods, 3. Analyze and reflect on student achievement in the context of the objectives and assessments. Reflections on the portfolio development outcomes and potential changes for future iterations of the course are also presented

How do right-to-work (RTW) laws impact workplace safety?

Ryan Dodds How do right-to-work (RTW) laws impact workplace safety? RTW laws allow employees covered by a union who are not union members to choose not to pay union dues. These laws weaken unions and decrease unionization. This study explores the impact of right-to-work (RTW) laws on workplace safety using a two-way fixed effects and a difference-in-differences approach, focusing on the five right-to-work laws passed by states in the 2010s. For my two-way fixed effects analysis, I construct a panel dataset from 2007-2019 using yearly state-level data from BLS for all 50 states with available data. My outcome variables are nonfatal occupational injury and illness rates and occupational fatality rates. I include state and year fixed effects with a large set of controls. I find that RTW laws reduce unionization and harm workplace safety. Specifically, I find that RTW laws decrease union coverage and membership by about 2.1% and 2.2%, respectively. I find that RTW laws increase occupational fatality rates by about 0.22 per 100,000 employees through decreasing unionization. This number is about 5% of the mean occupational fatality rate in my sample and suggests that right-to-work laws cost hundreds of lives each year. I also find, however, that right-to-work laws decrease the rate of reported nonfatal occupational injuries and illnesses by about 6%, and I am able to replicate this finding when looking at specific industries. I find that this decrease is likely being driven by increased reporting in unionized workplaces rather than a true improvement in workplace safety. Honors Project in Economics Advisor: Professor Gary Krueger April 30, 202

Invasion of winter moth in New England: Effects of defoliation and site quality on tree mortality.

Abstract Widespread and prolonged defoliation by the European winter moth, Operophtera brumata L., has occurred in forests of eastern Massachusetts for more than a decade and populations of winter moth continue to invade new areas of New England. This study characterized the forests of eastern Massachusetts invaded by winter moth and related the duration of winter moth defoliation estimated using dendrochronology to observed levels of tree mortality and understory woody plant density. Quercus basal area mortality in mixed Quercus and mixed Quercus-Pinus strobus forests in eastern Massachusetts ranged from 0-30%; mortality of Quercus in these forests was related to site quality and the number of winter moth defoliation events. In addition, winter moth defoliation events lead to a subsequent increase in understory woody plant density. Our results indicate that winter moth defoliation has been an important disturbance in New England forests that may have lasting impacts

Engineering evaluations and studies. Report for Ku-band studies, exhibit A

System performance aspects of the Ku band radar communication hardware and investigations into the Ku band/payload interfaces are discussed. The communications track problem caused by the excessive signal dynamic range at the servo input was investigated. The management/handover logic is discussed and a simplified description of the transmitter enable logic function is presented. Output noise produced by a voltage-controlled oscillator chip used in the SPA return-link channel 3 mid-bit detector is discussed. The deployed assembly (DA) and EA-2 critical design review data are evaluated. Cross coupling effects on antenna servo stability were examined. A series of meetings on the acceptance test specification for the deployed assembly is summarized