5,650 research outputs found
New Regulators for Quantum Field Theories with Compactified Extra Dimensions. I: Fundamentals
In this paper, we propose two new regulators for quantum field theories in
spacetimes with compactified extra dimensions. We refer to these regulators as
the ``extended hard cutoff'' (EHC) and ``extended dimensional regularization''
(EDR). Although based on traditional four-dimensional regulators, the key new
feature of these higher-dimensional regulators is that they are specifically
designed to handle mixed spacetimes in which some dimensions are infinitely
large and others are compactified. Moreover, unlike most other regulators which
have been used in the extra-dimension literature, these regulators are designed
to respect the original higher-dimensional Lorentz and gauge symmetries that
exist prior to compactification, and not merely the four-dimensional symmetries
which remain afterward. This distinction is particularly relevant for
calculations of the physics of the excited Kaluza-Klein modes themselves, and
not merely their radiative effects on zero modes. By respecting the full
higher-dimensional symmetries, our regulators avoid the introduction of
spurious terms which would not have been easy to disentangle from the physical
effects of compactification. As part of our work, we also derive a number of
ancillary results. For example, we demonstrate that in a gauge-invariant
theory, analogues of the Ward-Takahashi identity hold not only for the usual
zero-mode (four-dimensional) photons, but for all excited Kaluza-Klein photons
as well.Comment: 47 pages, LaTeX, 3 figure
'An Apotheosis of Well-Being': Durkheim on austerity and double-dip recessions
This article is an attempt to contribute a view on the economic crisis from classical sociology, a voice often missing from the sociological response to the crisis. The work of Émile Durkheim provides a unique perspective here centred on morality and inequality produced in a historical context akin to our neoliberal times. It is argued there are four key points to take from Durkheim’s work. Firstly, that the initial credit crunch can be more fully understood with reference to the economic anomie which Durkheim sees as ‘chronic’ in a time of marketization. Secondly, that this creates an antagonistic relationship between a supposedly self-dependent rich and lazy poor. Thirdly, this conception of self-dependency and individual initiative makes any attempt to regulate the economy akin to sacrilege. Finally, the state is unwilling to intervene due to the emergence of ‘pseudo-democracies’. Therefore, Durkheim’s theory accounts for the initial crisis, austerity and double-dip recessions in a sociological framework. The article concludes by returning to the centrality of morality to the crisis for Durkheim and highlighting the omission of this in contemporary debates
Integrated Laboratory Demonstrations of Multi-Object Adaptive Optics on a Simulated 10-Meter Telescope at Visible Wavelengths
One important frontier for astronomical adaptive optics (AO) involves methods
such as Multi-Object AO and Multi-Conjugate AO that have the potential to give
a significantly larger field of view than conventional AO techniques. A second
key emphasis over the next decade will be to push astronomical AO to visible
wavelengths. We have conducted the first laboratory simulations of wide-field,
laser guide star adaptive optics at visible wavelengths on a 10-meter-class
telescope. These experiments, utilizing the UCO/Lick Observatory's Multi-Object
/ Laser Tomography Adaptive Optics (MOAO/LTAO) testbed, demonstrate new
techniques in wavefront sensing and control that are crucial to future on-sky
MOAO systems. We (1) test and confirm the feasibility of highly accurate
atmospheric tomography with laser guide stars, (2) demonstrate key innovations
allowing open-loop operation of Shack-Hartmann wavefront sensors (with errors
of ~30 nm) as will be needed for MOAO, and (3) build a complete error budget
model describing system performance. The AO system maintains a performance of
32.4% Strehl on-axis, with 24.5% and 22.6% at 10" and 15", respectively, at a
science wavelength of 710 nm (R-band) over the equivalent of 0.8 seconds of
simulation. The MOAO-corrected field of view is ~25 times larger in area than
that limited by anisoplanatism at R-band. Our error budget is composed of terms
verified through independent, empirical experiments. Error terms arising from
calibration inaccuracies and optical drift are comparable in magnitude to
traditional terms like fitting error and tomographic error. This makes a strong
case for implementing additional calibration facilities in future AO systems,
including accelerometers on powered optics, 3D turbulators, telescope and LGS
simulators, and external calibration ports for deformable mirrors.Comment: 29 pages, 11 figures, submitted to PAS
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The value in de-emphasizing structure in liquidity
In the set of commentaries on liquidity entitled “The continuing significance of social structure in liquid modernity,” three sets of authors set out to examine the relationship between liquidity and structure, value, and distinction. In doing so, they attempt to marry theories which argue against sociologist Zygmunt Bauman’s central thesis that societal structures are shifting with his seminal construct of liquidity, an exercise that has mixed results. All three sets of authors have engaged with Bauman’s conceptualization of liquid modernity as well as our conceptualization of liquid consumption and its consequences. In this response to the commentaries, we clarify how we understand Bauman and how we have used his ideas in our theorizing, engage with the three sets of author’s advocacy for emphasizing the continuing relevance of structure within liquidity, and, finally, sum up how de-emphasizing structure has and can continue to lead to important new insights in marketing theory
Initial experience in treating lung cancer with helical tomotherapy
Helical tomotherapy is a new form of image-guided radiation therapy that combines features of a linear accelerator and a helical computed tomography (CT) scanner. Megavoltage CT (MVCT) data allow the verification and correction of patient setup on the couch by comparison and image registration with the kilovoltage CT multi-slice images used for treatment planning. An 84-year-old male patient with Stage III bulky non-small cell lung cancer was treated on a Hi-ART II tomotherapy unit. Daily MVCT imaging was useful for setup corrections and signaled the need to adapt the delivery plan when the patient’s anatomy changed significantly
Looking both ways: A review of methods for assessing research impacts on policy and the policy utilisation of research
Background: Measuring the policy and practice impacts of research is becoming increasingly important. Policy impacts can be measured from two directions – tracing forward from research and tracing backwards from a policy outcome. In this review, we compare these approaches and document the characteristics of studies assessing research impacts on policy and the policy utilisation of research.
Methods: Keyword searches of electronic databases were conducted in December 2016. Included studies were published between 1995 and 2016 in English and reported methods and findings of studies measuring policy impacts of specified health research, or research use in relation to a specified health policy outcome, and reviews reporting methods of research impact assessment. Using an iterative data extraction process, we developed a framework to define the key elements of empirical studies (assessment reason, assessment direction, assessment starting point, unit of analysis, assessment methods, assessment endpoint and outcomes assessed) and then documented the characteristics of included empirical studies according to this framework.
Results: We identified 144 empirical studies and 19 literature reviews. Empirical studies were derived from two parallel streams of research of equal size, which we termed ‘research impact assessments’ and ‘research use assessments’. Both streams provided insights about the influence of research on policy and utilised similar assessment methods, but approached measurement from opposite directions. Research impact assessments predominantly utilized forward tracing approaches while the converse was true for research use assessments. Within each stream, assessments focussed on narrow or broader research/policy units of analysis as the starting point for assessment, each with associated strengths and limitations. The two streams differed in terms of their relative focus on the contributions made by specific research (research impact assessments) versus research more generally (research use assessments) and the emphasis placed on research and the activities of researchers in comparison to other factors and actors as influencers of change.
Conclusions: The Framework presented in this paper provides a mechanism for comparing studies within this broad field of research enquiry. Forward and backward tracing approaches, and their different ways of ‘looking’, tell a different story of research-based policy change. Combining approaches may provide the best way forward in terms of linking outcomes to specific research, as well as providing a realistic picture of research influence
Strangers of the north: South Asians, cricket and the culture of ‘Yorkshireness’
As a county, Yorkshire is what Wagg and Russell refer to as a ‘cultural region’: an imagined space, where culture is constructed, refined and articulated by a set of discursive relationships between local populations and a whole range of cultural forms. In this context however, culture is conceived as something which belongs to, and is only accessible by, certain groups of people. Our focus in this article is on the culture of Yorkshire cricket. Historically, Yorkshire cricket has been linked with white male privilege and some studies have shown that people within Yorkshire take a degree of pride in this. Consequently, the county and its cricket club have faced frequent accusations from minority ethnic communities of inveterate and institutionalised racism. Drawing upon Bauman’s notion of ‘liquid modernity’, we argue that the processes of deregulation and individualisation championed by New Right policies have led to a divorce between power and politics, a corner stone of the old solid modern world. This in turn has led to an erosion of the state, causing individuals to navigate turbulent life projects which are consistently haunted by the spectres of fear and insecurity. Such an environment has caused cricket to be pushed further behind gated social spaces, in an attempt to maintain a semblance of ‘community’
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