12,411 research outputs found
New tests of the pp-wave correspondence.
The pp-wave/SYM correspondence is an equivalence relation, H string = Δ-J , between the hamiltonian H string of string field theory in the pp-wave background and the dilatation operator Δ in = 4 Super Yang-Mills in the double scaling limit. We calculate matrix elements of these operators in string field theory and in gauge theory. In the string theory Hilbert space we use the natural string basis, and in the gauge theory we use the basis which is isomorphic to it. States in this basis are specific linear combinations of the original BMN operators, and were constructed previously for the case of two scalar impurities. We extend this construction to incorporate BMN operators with vector and mixed impurities. This enables us to verify from the gauge theory perspective two key properties of the three-string interaction vertex of Spradlin and Volovich: (1) the vanishing of the three-string amplitude for string states with one vector and one scalar impurity; and (2) the relative minus sign in the string amplitude involving states with two vector impurities compared to that with two scalar impurities. This implies a spontaneous breaking of the 2 symmetry of the string field theory in the pp-wave background. Furthermore, we calculate the gauge theory matrix elements of Δ-J for states with an arbitrary number of scalar impurities. In all cases we find perfect agreement with the corresponding string amplitudes derived from the three-string vertex
Thinking territory historically.
BACKGROUND:
While the randomised controlled trial (RCT) is generally regarded as the design of
choice for assessing the effects of health care, within the social sciences there is
considerable debate about the relative suitability of RCTs and non-randomised
studies (NRSs) for evaluating public policy interventions.
// OBJECTIVES:
To determine whether RCTs lead to the same effect size and variance as NRSs of
similar policy interventions; and whether these findings can be explained by other
factors associated with the interventions or their evaluation.
// METHODS:
Analyses of methodological studies, empirical reviews, and individual health and
social services studies investigated the relationship between randomisation and
effect size of policy interventions by:
1) Comparing controlled trials that are identical in all respects other than the use of
randomisation by 'breaking' the randomisation in a trial to create non-randomised
trials (re-sampling studies).
2) Comparing randomised and non-randomised arms of controlled trials mounted
simultaneously in the field (replication studies).
3) Comparing similar controlled trials drawn from systematic reviews that include
both randomised and non-randomised studies (structured narrative reviews and
sensitivity analyses within meta-analyses).
4) Investigating associations between randomisation and effect size using a pool of
more diverse RCTs and NRSs within broadly similar areas (meta-epidemiology).
// RESULTS:
Prior methodological reviews and meta-analyses of existing reviews comparing
effects from RCTs and nRCTs suggested that effect sizes from RCTs and nRCTs
may indeed differ in some circumstances and that these differences may well be
associated with factors confounded with design.
Re-sampling studies offer no evidence that the absence of randomisation directly
influences the effect size of policy interventions in a systematic way. No consistent
explanations were found for randomisation being associated with changes in effect
sizes of policy interventions in field trials
Magnetic Fields in Dark Cloud Cores: Arecibo OH Zeeman Observations
We have carried out an extensive survey of magnetic field strengths toward
dark cloud cores in order to test models of star formation: ambipolar-diffusion
driven or turbulence driven. The survey involved hours of observing
with the Arecibo telescope in order to make sensitive OH Zeeman observations
toward 34 dark cloud cores. Nine new probable detections were achieved at the
2.5-sigma level; the certainty of the detections varies from solid to marginal,
so we discuss each probable detection separately. However, our analysis
includes all the measurements and does not depend on whether each position has
a detection or just a sensitive measurement. Rather, the analysis establishes
mean (or median) values over the set of observed cores for relevant
astrophysical quantities. The results are that the mass-to-flux ratio is
supercritical by , and that the ratio of turbulent to magnetic energies
is also . These results are compatible with both models of star
formation. However, these OH Zeeman observations do establish for the first
time on a statistically sound basis the energetic importance of magnetic fields
in dark cloud cores at densities of order cm, and they lay
the foundation for further observations that could provide a more definitive
test.Comment: 22 pages, 2 figures, 2 table
'It's a Form of Freedom': The experiences of people with disabilities within equestrian sport
This paper explores the embodied, gendered experiences of disabled horse‐riders. Drawing on data from five in‐depth interviews with paradressage riders, the ways in which their involvement in elite disability sport impacts upon their sense of identity and confidence are explored, as well as the considerable health and social benefits that this involvement brings. Social models of disability are employed and the shortcomings of such models, when applied to disability sport, are highlighted. The data presented here demonstrates the necessity of seeing disability sport as an embodied experience and acknowledging the importance of impairment to the experiences of disabled athletes. Living within an impaired body is also a gendered experience and the implications of this when applied to elite disability sport are considered
Exploring the energy disposal immediately after bond-breaking in solution:the wavelength-dependent excited state dissociation pathways of para-methylthiophenol
From Photodriven Charge Accumulation to Fueling Enzyme Cascades in Molecular Factories
In a multi-disciplinary team effort we gather experts on light-to-chemical energy conversion, artificial metalloenzymes, and bio-inspired polymer vesicles in order to construct molecular factories which produce added-value chemicals in an overall process fueled by solar energy. We outline our long-term vision and discuss specific challenges associated with this endeavor
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Alternative outlets for sustaining photosynthetic electron transport during dark-to-light transitions.
Environmental stresses dramatically impact the balance between the production of photosynthetically derived energetic electrons and Calvin-Benson-Bassham cycle (CBBC) activity; an imbalance promotes accumulation of reactive oxygen species and causes cell damage. Hence, photosynthetic organisms have developed several strategies to route electrons toward alternative outlets that allow for storage or harmless dissipation of their energy. In this work, we explore the activities of three essential outlets associated with Chlamydomonas reinhardtii photosynthetic electron transport: (i) reduction of O2 to H2O through flavodiiron proteins (FLVs) and (ii) plastid terminal oxidases (PTOX) and (iii) the synthesis of starch. Real-time measurements of O2 exchange have demonstrated that FLVs immediately engage during dark-to-light transitions, allowing electron transport when the CBBC is not fully activated. Under these conditions, we quantified maximal FLV activity and its overall capacity to direct photosynthetic electrons toward O2 reduction. However, when starch synthesis is compromised, a greater proportion of the electrons is directed toward O2 reduction through both the FLVs and PTOX, suggesting an important role for starch synthesis in priming/regulating CBBC and electron transport. Moreover, partitioning energized electrons between sustainable (starch; energetic electrons are recaptured) and nonsustainable (H2O; energetic electrons are not recaptured) outlets is part of the energy management strategy of photosynthetic organisms that allows them to cope with the fluctuating conditions encountered in nature. Finally, unmasking the repertoire and control of such energetic reactions offers new directions for rational redesign and optimization of photosynthesis to satisfy global demands for food and other resources
The “We” in Cyber Bullying: Response 1
This practical text explores contemporary case scenarios that arise in school counseling with children and adolescents. Throughout 30 chapters on a diverse range of topics, several school counseling experts analyze and discuss each incident from a best practices perspective. Topics are organized around the CACREP Standards and incidents include a list of related supplemental readings, online resources, and suggested learning activities. Issues explored include trauma, drug use, pregnancy, cyberbullying, suicide, gangs, parental conflicts, sexual orientation, third-culture students, student career development, and ethical and professional dilemmas. Tarrell Awe Agahe Portman, PhD, is the dean of the College of Education at Winona State University. Chris Wood, PhD, is an associate professor in the Counselor Education program at the University of Nevada, Las Vegas. Heather J. Fye, PhD, is an assistant professor in the Counselor Education program at the University of Alabama
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