1,188 research outputs found
Allostery without conformation change: modelling protein dynamics at multiple scales
The original ideas of Cooper and Dryden, that allosteric signalling can be induced between distant binding sites on proteins without any change in mean structural conformation, has proved to be a remarkably prescient insight into the rich structure of protein dynamics. It represents an alternative to the celebrated MonodâWymanâChangeux mechanism and proposes that modulation of the amplitude of thermal fluctuations around a mean structure, rather than shifts in the structure itself, give rise to allostery in ligand binding. In a complementary approach to experiments on real proteins, here we take a theoretical route to identify the necessary structural components of this mechanism. By reviewing and extending an approach that moves from very coarse-grained to more detailed models, we show that, a fundamental requirement for a body supporting fluctuation-induced allostery is a strongly inhomogeneous elastic modulus. This requirement is reflected in many real proteins, where a good approximation of the elastic structure maps strongly coherent domains onto rigid blocks connected by more flexible interface regions
Analysis of and with QCD sum rules
In this article, we calculate the masses and residues of the heavy baryons
and with spin-parity with the QCD
sum rules. The numerical values are compatible with experimental data and other
theoretical estimations.Comment: 13 pages, 8 figures, slight versio
One Loop Calculations in Gauge Theories Regulated on an - Lattice
In earlier work, the planar diagrams of gauge theory have been
regulated on the light-cone by a scheme involving both discrete and
. The transverse coordinates remain continuous, but even so all
diagrams are rendered finite by this procedure. In this scheme quartic
interactions are represented as two cubics mediated by short lived fictitious
particles whose detailed behavior could be adjusted to retain properties of the
continuum theory, at least at one loop. Here we use this setup to calculate the
one loop three gauge boson triangle diagram, and so complete the calculation of
diagrams renormalizing the coupling to one loop. In particular, we find that
the cubic vertex is correctly renormalized once the couplings to the fictitious
particles are chosen to keep the gauge bosons massless.Comment: 26 pages, 36 figure
The Hadron Spectrum from Lattice QCD
Determining the hadron spectrum and hadron properties beyond the ground
states is a challenge in lattice QCD. Most of these results have been in the
quenched approximation but now we are entering the dynamical era. I review some
of the ideas and methods of the lattice approach, concentrating on a few
examples and on results obtained for Chirally Improved (CI) fermions.Comment: 18 pages, 12 figures, 1 table; Notes based on a lecture at the Int.
School of Nuclear Physics, 29th Course, 16-24. Sept. 2007, Erice/Sicily,
"Quarks in Hadrons and Nuclei"; minor modification
Gauge-ball spectrum of the four-dimensional pure U(1) gauge theory
We investigate the continuum limit of the gauge-ball spectrum in the
four-dimensional pure U(1) lattice gauge theory. In the confinement phase we
identify various states scaling with the correlation length exponent . The square root of the string tension also scales with this
exponent, which agrees with the non-Gaussian fixed point exponent recently
found in the finite size studies of this theory. Possible scenarios for
constructing a non-Gaussian continuum theory with the observed gauge-ball
spectrum are discussed. The state, however, scales with a Gaussian
value . This suggests the existence of a second, Gaussian
continuum limit in the confinement phase and also the presence of a light or
possibly massless scalar in the non-Gaussian continuum theory. In the Coulomb
phase we find evidence for a few gauge-balls, being resonances in multi-photon
channels; they seem to approach the continuum limit with as yet unknown
critical exponents. The maximal value of the renormalized coupling in this
phase is determined and its universality confirmed.Comment: 46 pages, 12 figure
Potential for Supernova Neutrino Detection in MiniBooNE
The MiniBooNE detector at Fermilab is designed to search for oscillation appearance at and to make a
decisive test of the LSND signal. The main detector (inside a veto shield) is a
spherical volume containing 0.680 ktons of mineral oil. This inner volume,
viewed by 1280 phototubes, is primarily a \v{C}erenkov medium, as the
scintillation yield is low. The entire detector is under a 3 m earth
overburden. Though the detector is not optimized for low-energy (tens of MeV)
events, and the cosmic-ray muon rate is high (10 kHz), we show that MiniBooNE
can function as a useful supernova neutrino detector. Simple trigger-level cuts
can greatly reduce the backgrounds due to cosmic-ray muons. For a canonical
Galactic supernova at 10 kpc, about 190 supernova
events would be detected. By adding MiniBooNE to the international network of
supernova detectors, the possibility of a supernova being missed would be
reduced. Additionally, the paths of the supernova neutrinos through Earth will
be different for MiniBooNE and other detectors, thus allowing tests of
matter-affected mixing effects on the neutrino signal.Comment: Added references, version to appear in PR
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Sexuality, Intimacy and Older Care Home Residents.
YESOver half a million people aged 65+ live in care homes (ONS 2011). Yet, sex, sexuality and intimacy and old people remain overlooked in social policy and professional practice (Hafford-Letchfield 2008). We explore narratives from a feasibility study based in Northwest England that consulted on the significance of researching sexuality and intimacy. We draw on narratives generated with two focus groups of professional carers (n = 16) and interviews with three residents, (two male and one female) and four female spouses (n = 7). All three types of stakeholders expressed concern about privacy and environmental impediments to intimacy (e.g. shortage of double rooms). However, distinct concerns were expressed by each group. Residentsâ expressed scepticism that the topic was âtoo personalâ, that old people were post-sexual or that sex/intimacy were part of range of needs and could be eclipsed by those relating to grand-parenting, avoiding isolation and personalization of care. Spouses emphasized the importance of intimacy over sex/sexuality as an indicator of the depth and longevity of a relationship but were concerned about unmet needs and loss of influence over their partnersâ care. Obliged to meet a complex of legal, professional, ethical and interpersonal obligations, care staff articulated a need for guidance to help them support residents and their significant others. We conclude with practical recommendations that address barriers to enabling intimacy
Plasmonic excitations in noble metals: The case of Ag
The delicate interplay between plasmonic excitations and interband
transitions in noble metals is described by means of {\it ab initio}
calculations and a simple model in which the conduction electron plasmon is
coupled to the continuum of electron-hole pairs. Band structure effects,
specially the energy at which the excitation of the -like bands takes place,
determine the existence of a subthreshold plasmonic mode, which manifests
itself in Ag as a sharp resonance at 3.8 eV. However, such a resonance is not
observed in the other noble metals. Here, this different behavior is also
analyzed and an explanation is provided.Comment: 9 pages, 8 figure
Translation to practice: a randomised controlled study of an evidenced based booklet targeted at breast care nurses in the United Kingdom
BACKGROUND: In the United Kingdom (UK), it was documented that a problem of knowledge transfer existed within the speciality of breast-cancer care, thus depriving patients of receiving optimal care. Despite increasingly robust research evidence indicating recommendation of whole body exercise for people affected by breast cancer, commensurate changes to practice were not noted amongst breast-care nurses (BCNs).
AIM: To evaluate the effect of a targeted booklet, Exercise and Breast Cancer: A Booklet for Breast-Care Nurses, on changes in knowledge, reported practice, and attitudes of BCNs in the UK.
METHOD: A prospective, experimental approach was used for designing a pre- and post-test randomised controlled study. Comparisons of knowledge, reported practice, and attitudes based on responses to a questionnaire were made at two time-points in two groups of BCNs (control and experimental). The unit of randomisation and analysis was hospital clusters of BCNs. The sample comprised 92 nurses from 62 hospitals. Analysis consisted of descriptive statistics and clustered regression techniques: clustered logistic regression for knowledge items, clustered linear regression for knowledge scores, ologit for attitude and reported practice items, and clustered multiple regression for paired and multiple variable analysis.
RESULTS: A statistically significant increase in knowledge and changes in reported practice and attitudes were found. Robust variables affecting knowledge acquisition were: promotion of health, promotion of exercise, and understanding how exercise can reduce cancer-related fatigue.
DISCUSSION: The study has shown that evidence-based printed material, such as an information booklet, can be used as an effective research dissemination method when developed for needs, values, and context of a target audience.
CONCLUSIONS: This practical approach to research dissemination could be replicated and applied to other groups of nurses.</p
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