187 research outputs found
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Salt Processing Through Ion Exchange at the Savannah River Site Selection of Exchange Media and Column Configuration - 9198
The Department of Energy (DOE) has developed, modeled, and tested several different ion exchange media and column designs for cesium removal. One elutable resin and one non-elutable resin were considered for this salt processing application. Deployment of non-elutable Crystalline Silicotitanate and elutable Resorcinol Formaldehyde in several different column configurations were assessed in a formal Systems Engineering Evaluation (SEE). Salt solutions were selected that would allow a grouping of non-compliant tanks to be closed. Tests were run with the elutable resin to determine compatibility with the resin configuration required for an in-tank ion exchange system. Models were run to estimate the ion exchange cycles required with the two resins in several column configurations. Material balance calculations were performed to estimate the impact on the High Level Waste (HLW) system at the Savannah River Site (SRS). Conceptual process diagrams were used to support the hazard analysis. Data from the hazard analysis was used to determine the relative impact on safety. This report will discuss the technical inputs, SEE methods, results and path forward to complete the technical maturation of ion exchange
High Energy Neutrinos from the TeV Blazar 1ES 1959+650
The AMANDA neutrino telescope has recently reported the detection of
high-energy neutrinos spatially and temporally coincident with the flaring of
the TeV blazar 1ES 1959+650. At present, the statistical significance of this
observation cannot be reliably assessed, however. In this letter, we
investigate whether circumstances exist where the source can produce the flux
implied by the coincident events. We show that if the TeV gamma-ray emission
observed from 1ES 1959+650 or other nearby TeV blazars is the result of
accelerated protons interacting with nucleons, it is reasonable that AMANDA
could detect several events during a flaring period. Such rates require that
the spectral index of the source be rather high (for instance for 1ES
1959+650) and that the Lorentz factor of the jet be fairly small ().Comment: 9 pages, 2 figure
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Dialectic tensions in the financial markets: a longitudinal study of pre- and post-crisis regulatory technology
This article presents the findings from a longitudinal research study on regulatory technology in the UK financial services industry. The financial crisis with serious corporate and mutual fund scandals raised the profile of
compliance as governmental bodies, institutional and private investors introduced a âtsunamiâ of financial regulations. Adopting a multi-level analysis, this study examines how regulatory technology was used by financial firms to meet their compliance obligations, pre- and post-crisis. Empirical data collected over 12 years examine the deployment of
an investment management system in eight financial firms. Interviews with public regulatory bodies, financial
institutions and technology providers reveal a culture of compliance with increased transparency, surveillance and
accountability. Findings show that dialectic tensions arise as the pursuit of transparency, surveillance and
accountability in compliance mandates is simultaneously rationalized, facilitated and obscured by regulatory
technology. Responding to these challenges, regulatory bodies continue to impose revised compliance mandates on
financial firms to force them to adapt their financial technologies in an ever-changing multi-jurisdictional regulatory landscape
Synoptic studies of seventeen blazars detected in very high-energy gamma-rays
Since 2002, the number of detected blazars at gamma-ray energies above 100
GeV has more than doubled. I study 17 blazars currently known to emit E>100 GeV
gamma rays. Their intrinsic energy spectra are reconstructed by removing
extragalactic background light attenuation effects. Luminosity and spectral
slope in the E>100 GeV region are then compared and correlated among each
other, with X-ray, optical and radio data, and with the estimated black hole
(BH) masses of the respective host galaxies.
According to expectations from synchrotron self-Compton emission models, a
correlation on the 3.6-sigma significance level between gamma-ray and X-ray
fluxes is found, while correlations between gamma-ray and optical/radio fluxes
are less pronounced. Further, a general hardening of the E>100 GeV spectra with
increasing gamma-ray luminosity is observed. This goes in line with a
correlation of the gamma-ray luminosity and the synchrotron peak frequency,
which is also seen. Tests for possible selection effects reveal a hardening of
the spectra with increasing redshift. The gamma-ray emission might depend on
the mass of the central BH. The studied blazars show no correlation of the BH
masses with the spectral index and the luminosity in the E>100 GeV region.
Also temporal properties of the X-ray and E>100 GeV gamma-ray flux are
considered. No general trends are found, except that the blazars with the most
massive BHs do not show particularly high duty cycles. In general, VHE flare
time-scales are not found to scale with the BH mass.
As a specific application of the luminosity study, a constraint for the still
undetermined redshift of the blazar PG 1553+113 is discussed.Comment: 17 pages, 18 figures, MNRAS in press. Abstract extended; minor
modifications in sect. 3, 5.5; Fig. 7c corrected; references update
A Search for TeV Gamma-Ray Emission from High-Peaked Flat Spectrum Radio Quasars Using the Whipple Air-Cherenkov Telescope
Blazars have traditionally been separated into two broad categories based
upon their optical emission characteristics; BL Lacs, with faint or no emission
lines, and flat spectrum radio quasars (FSRQs) with prominent, broad emission
lines. The spectral energy distribution of FSRQs has generally been thought of
as being more akin to the low-peaked BL Lacs, which exhibit a peak in the
infrared region of the spectrum, as opposed to high-peaked BL Lacs (HBLs),
which exhibit a peak in UV/X-ray region of the spectrum. All blazars currently
confirmed as sources of TeV emission are HBLs. Recent surveys have found
several FSRQs exhibiting spectral properties similar to HBLs, particularly the
synchrotron peak frequency. These objects are potential sources of TeV emission
according to several models of blazar jet emission and blazar evolution.
Measurements of TeV flux or upper limits could impact existing theories
explaining the links between different blazar types and could have a
significant impact on our understanding of the nature of objects that are
capable of TeV emission. In particular, the presence (or absence) of TeV
emission from FSRQs could confirm (or cast doubt upon) recent evolutionary
models that expect intermediate objects in a transitionary state between FSRQ
and BL Lac. The Whipple 10 meter imaging air-Cherenkov gamma-ray telescope is
well suited for TeV gamma-ray observations. Using the Whipple telescope, we
have taken data on a small selection of nearby(z<0.1 in most cases),
high-peaked FSRQs. Although one of the objects, B2 0321+33, showed marginal
evidence of flaring, no significant emission was detected. The implications of
this paucity of emission and the derived upper limits are discussed.Comment: accepted for publication in Astrophysical Journa
The politics of access in fieldwork: Immersion, backstage dramas and deception
YesGaining access in fieldwork is crucial to the success of research, and may often be problematic because it involves working in complex social situations. This paper examines the intricacies of access, conceptualizing it as a fluid, temporal and political process that requires sensitivity to social issues and to potential ethical choices faced by both researchers and organization members. Our contribution lies in offering ways in which researchers can reflexively negotiate the challenges of access by: 1. Underscoring the complex and relational nature of access by conceptualizing three relational perspectives â instrumental, transactional and relational â proposing the latter as a strategy for developing a diplomatic sensitivity to the politics of access; 2. Explicating the political, ethical and emergent nature of access by framing it as an ongoing process of immersion, backstage dramas, and deception; and 3. Offering a number of relational micropractices to help researchers negotiate the complexities of access. We illustrate the challenges of gaining and maintaining access through examples from the literature and from Rafaelâs attempts to gain access to carry out fieldwork in a Police Force
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The evolution and adoption of equity crowdfunding: entrepreneur and investor entry into a new market
Equity crowdfunding (ECF) offers entrepreneurs an online social media marketplace where they can access numerous potential investors who, in exchange for an ownership stake, may supply them with finance. In this paper, we describe the evolution of this market in the UK. Using an inductive qualitative longitudinal research design, we analyse the emerging views of entrepreneurs and investors towards ECF. Our interviewees include large and small-scale investors, as well as market participants who have chosen not to invest or raise funds via ECF. We find that the large financial flows to entrepreneurs in the UK via the ECF platforms, nearly half a billion GBP since 2011, have probably been largely incremental to traditional sources of early stage entrepreneurial finance. Moreover, our research indicates that for the most part, investors appear to understand and appropriately evaluate the risks that they are bearing; ECF investments are perceived as a high risk, high return component within individualsâ portfolios. Investors also use their communication with peers and entrepreneurs via the ECF platform as a learning tool. On the entrepreneursâ side, ECF allows them to test their products, to develop their brand, to build a loyal customer base and to turn customers into investors. We conclude that policymakers, with the support of a locally appropriate regulatory framework, could support equity crowdfunding as one of the market choices available for entrepreneurs looking to start or grow their ventures
Ethnic entrepreneurs and online home-based businesses: an exploratory study
This exploratory, qualitative study considers how online home-based businesses offer opportunities for ethnic entrepreneurs to âbreak outâ of traditional highly competitive and low margin sectors. Previous studies have found a positive association between ethnic minoritiesâ high levels of entrepreneurship and home computer use in ethnic groups. Despite these associations, previous studies have overlooked the particular opportunities offered by home-based online businesses to ethnic entrepreneurs. The study adopts mixed embeddedness as a theoretical lens to guide interviews with 22 ethnic entrepreneurs who have started online home-based businesses in the UK. We find online home-based businesses offer ethnic entrepreneurs novel opportunities to draw on their ethnic advantages and address the constraints they face. The unique affordances of this type of business allow entrepreneurs to develop the necessary IT skills by self-learning and experimentation and to sub-contract more difficult or time consuming aspects to others. The findings also show that, consistent with the theory of mixed embeddedness, whilst the entrepreneurs are influenced by social, economic and institutional forces, online businesses allow them to exert their own agency and provide opportunities to uniquely shape these forces
Seven features of safety in maternity units: a framework based on multisite ethnography and stakeholder consultation
Background: Reducing avoidable harm in maternity services is a priority globally. As well as learning from mistakes, it is important to produce rigorous descriptions of âwhat good looks likeâ. Objective: We aimed to characterise features of safety in maternity units and to generate a plain language framework that could be used to guide learning and improvement. Methods: We conducted a multisite ethnography involving 401 hours of non-participant observations 33 semistructured interviews with staff across six maternity units, and a stakeholder consultation involving 65 semistructured telephone interviews and one focus group. Results: We identified seven features of safety in maternity units and summarised them into a framework, named For Us (For Unit Safety). The features include: (1) commitment to safety and improvement at all levels, with everyone involved; (2) technical competence, supported by formal training and informal learning; (3) teamwork, cooperation and positive working relationships; (4) constant reinforcing of safe, ethical and respectful behaviours; (5) multiple problem-sensing systems, used as basis of action; (6) systems and processes designed for safety, and regularly reviewed and optimised; (7) effective coordination and ability to mobilise quickly. These features appear to have a synergistic character, such that each feature is necessary but not sufficient on its own: the features operate in concert through multiple forms of feedback and amplification. Conclusions: This large qualitative study has enabled the generation of a new plain language frameworkâFor Usâthat identifies the behaviours and practices that appear to be features of safe care in hospital-based maternity units
Redefining professional identity: the voice of a language teacher in a context of collaborative learning
Following a narrative and biographic approach, in this study, we present the case of an in-service language teacher and her professional learning trajectory in the context of the project âLanguages and education: constructing and sharing train- ingâ. This project aimed at the construction of a collaborative teacher education context for learning and transformation of experiences, views and practices in language education, and involved teachers, teacher educators and researchers. Based on a single case study, the analysis tries to disclose the teacherâs discur- sive displacements as hints of professional transformation while she reinterprets the learning taking place in the collaborative education process. The signs of change are visible in the way she constructs meanings regarding her professional identity, re-identifies her mission as a language teacher and reconsiders her pro- fessional identity. Finally, we reflect upon how collaborative teacher education scenarios may foster teachersâ personal professional learning and renewed self- images
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