Explicit expression for the photon number emission in synchrotron radiation

An explicit and remarkably simple one-dimensional integral expression is derived for the mean number of photons emitted per revolution in synchrotron radiation. The familiar high-energy expression $5\pi\alpha/\sqrt{3(1-\beta^2)}$, printed repeatedly in the literature, is found to be inaccurate and only truly asymptotic with relative errors of 160%, 82% for $\beta=0.8$, 0.9, respectively. A new improved high-energy expression for is given.Comment: LaTeX, 3 pages, no figur

Assessing the Effectiveness of a Computer Simulation in Introductory Undergraduate Environments

We present studies documenting the effectiveness of using a computer simulation, specifically the Circuit Construction Kit (CCK) developed as part of the Physics Education Technology Project (PhET) [1, 2], in two environments: an interactive college lecture and an inquiry-based laboratory. In the first study conducted in lecture, we compared students viewing CCK to viewing a traditional demonstration during Peer Instruction [3]. Students viewing CCK had a 47% larger relative gain (11% absolute gain) on measures of conceptual understanding compared to traditional demonstrations. These results led us to study the impact of the simulation's explicit representation for visualizing current flow in a laboratory environment, where we removed this feature for a subset of students. Students using CCK with or without the explicit visualization of current performed similarly to each other on common exam questions. Although the majority of students in both groups favored the use of CCK over real circuit equipment, the students who used CCK without the explicit current model favored the simulation more than the other grou

Climate modification and climate change debates amongst Soviet physical geographers, 1940s-1960s

This review provides an insight into some of the main themes characterizing the work of Soviet physical geographers concerning climate during the decade following the Second World War. Post-1945, pressure was placed upon geography via the state and the Academy of Sciences to ensure that its activities were of practical use to the development of the socialist economy and this was particularly evident in the case of work related to climate and climate modification. The review is divided into four main sections. First, it provides an understanding of the range of work carried out by physical geographers with respect to climate and related phenomena in the late 1940s and 1950s. Second, it focuses on the work of geographers and climatologists in relation to the heat and water balance at the earth's surface, which attracted considerable attention within geographical circles as well as more broadly within Soviet science during the 1950s. Third, it reflects upon the way in which Soviet geography utilized its understanding of climate systems in order to participate in national schemes concerned with the modification of the climate and the transformation of nature. Finally, the review highlights the maturing of climate modification debates among geographers and cognate scientists during the late 1950s and early 1960s with the emergence of competing discussions over the potential for human activity to result in both positive and negative consequences for the global climate system

The Business of Expectations: How Promissory Organisations Shape Technology & Innovation

The business of technological expectations has yet to be thoroughly explored by scholars interested in the role of expectations and visions in the emergence of technological innovations. However, intermediaries specialising in the production, commodification and selling of future-oriented knowledge have emerged to exert new kinds of influence on the shaping of technology and innovation. We focus on the work of those specialist forms of consultants known as ‘industry analysts’ and consider them as promissory organisations to capture the fact they are successful in mobilising and indeed increasingly organising expectations within procurement and innovation markets. Our aim is to highlight the important role these actors play in shaping technologies and in so doing how they typically exhibit complex and highly uneven forms of influence. The paper is organised around a central question: Why are certain kinds of promissory behaviour more influential than others? To answer this, we draw from the literature on technology expectations on discussions of the ‘constitutive’ nature of promises, which provides a useful but arguably partial analytical approach for articulating the dynamics and differences surrounding product based expectations. We thus supplement our understanding with recent developments in Economic Sociology and the Sociology of Finance where an ambitious theoretical framework is unfolding in relation to the ‘performativity of economic theory’. By contrasting different forms of promissory work conducted by industry analysts and varying forms of accountability to which this work is subject we begin to map out a typology that characterises promissory behaviour according to differences in kind and effect

Beyond The ERP Implementation Study: A New Approach To The Study Of Packaged Information Systems: The Biography Of Artifacts Framework

Scholarship addressing the social and organizational issues surrounding enterprise resource planning (ERP) systems is blossoming. However, many of these studies produce unhelpful readings of the characteristics of ERP and its implications for organizations. The typical ‘ERP implementation case study’ has been given undue emphasis within Information Systems (IS) research. Often influenced by constructivist frameworks and qualitative methodologies, including Actor Network Theory and ethnography, these approaches encourages actor-centered analysis and rich local pictures of the immediate response by organizations to these systems. However we are skeptical that the most useful way to study ERP is solely at the place where the user encounters it. One implication is that important influences from other levels and timeframes are missed from analysis. We propose an alternative research approach - the emerging ‘Biography of Artifacts Framework’ - that takes seriously the multiple locations and different timeframes in which ERP systems operate and evolve

Effects of drinking-water filtration on Cryptosporidium Seroepidemiology, Scotland

Continuous exposure to low levels of Cryptosporidium oocysts is associated with production of protective antibodies. We investigated prevalence of antibodies against the 27-kDa Cryptosporidium oocyst antigen among blood donors in 2 areas of Scotland supplied by drinking water from different sources with different filtration standards: Glasgow (not filtered) and Dundee (filtered). During 2006–2009, seroprevalence and risk factor data were collected; this period includes 2007, when enhanced filtration was introduced to the Glasgow supply. A serologic response to the 27-kDa antigen was found for ≈75% of donors in the 2 cohorts combined. Mixed regression modeling indicated a 32% step-change reduction in seroprevalence of antibodies against Cryptosporidium among persons in the Glasgow area, which was associated with introduction of enhanced filtration treatment. Removal of Cryptosporidium oocysts from water reduces the risk for waterborne exposure, sporadic infections, and outbreaks. Paradoxically, however, oocyst removal might lower immunity and increase the risk for infection from other sources

Reducing DCO registrations through electronic matching of cancer registry data and routine hospital data

The Thames Cancer Registry (TCR) has registered a high proportion of tumours from death certificate information only (DCO) registrations. This paper describes the results of a study set up to establish whether this proportion could be reduced by linking cancer registrations with routine hospital data from the Hospital Episodes Statistics (HES) data set using computerized matching. A total of 67 752 registrations were identified from the TCR. Matches were found in the HES data set for 66%. The proportion of cases retrieved for each tumour site was: 72% for colorectal cancer; 62% for cancer of the lung, trachea or bronchus; and 65% for female breast cancer. For all three tumour sites the proportion of matches found for patients registered from hospital case notes was higher than the proportion found for patients registered as DCOs (P< 0.0001 for all three tumour sites). Among matched DCO cases, 58% had at least one procedure recorded. DCO rates might be reduced by as much as 43% (from 17% of total registrations to less than 10%) for the three most common cancers if the method of electronic matching outlined here was used. Younger age groups, prognosis of tumour site and residence in North Thames region were all positively associated with successful matching (P< 0.0001 in all three cases). Many matched DCO cases were found to have had more than one admission for cancer. Among ordinary in-patient admissions, admissions to patients ratios of 1.5, 1.4 and 1.9 were found for colorectal, lung and breast cancers respectively. Of 5190 matched DCOs a procedure was recorded for 3013 (58%). HES data offer a useful aid to follow-up of case notes on patients identified to the registry by death certificates. Doubts about the completeness and accuracy of HES data mean case notes must remain the ‘gold standard’. © 2000 Cancer Research Campaig

Correlating Student Beliefs With Student Learning Using The Colorado Learning Attitudes about Science Survey

A number of instruments have been designed to probe the variety of attitudes, beliefs, expectations, and epistemological frames taught in our introductory physics courses. Using a newly developed instrument -- the Colorado Learning Attitudes about Science Survey (CLASS)[1] -- we examine the relationship between students' beliefs about physics and other educational outcomes, such as conceptual learning and student retention. We report results from surveys of over 750 students in a variety of courses, including several courses modified to promote favorable beliefs about physics. We find positive correlations between particular student beliefs and conceptual learning gains, and between student retention and favorable beliefs in select categories. We also note the influence of teaching practices on student beliefs