2,950 research outputs found
Field condensations and Noncritical String for c>1
Quantum theory of 2d gravity for is examined as a non-critical string
theory by taking account of the loop-correction of open strings whose end
points are on the 2d world surface of the closed string. This loop-correction
leads to a conformal anomaly, and we obtain a modified target-space action
which implies a new phase of the non-critical closed-string. In this phase, the
dual field of the gauge field, which lives on the boundary, condenses and the
theory can be extended to without any instability.Comment: 17 pages, Latex, no figur
Unpackaging demand for water service quality : evidence from conjoint surveys in Sri Lanka
In the early 2000s, the Government of Sri Lanka considered engaging private sector operators to manage water and sewerage services in two separate service areas: one in the town of Negombo (north of Colombo), and one stretching along the coastal strip (south from Colombo) from the towns of Kalutara to Galle. Since then, the government has abandoned the idea of setting up a public-private partnership in these two areas. This paper is part of a series of investigations to determine how these pilot private sector transactions (forming part of the overall water sector reform strategy) could be designed in such a manner that they would benefit the poor. The authors describe the results of a conjoint survey evaluating the factors that drive customer demand for alternative water supply and sanitation services in Sri Lanka. They show how conjoint surveys can be used to unpackage household demand for attributes of urban services and improve the design of infrastructure policies. They present conjoint surveys as a tool for field experiments and a source of valuable empirical data. In the study of three coastal towns in southwestern Sri Lanka the conjoint survey allows the authors to compare household preferences for four water supply attributes-price, quantity, safety, and reliability. They examine subpopulations of different income levels to determine if demand is heterogeneous. The case study suggests that households care about service quality (not just price). In general, the authors find that households have diverse preferences in terms of quantity, safety, and service options, but not with regard to hours of supply. In particular, they find that the poor have lower ability to trade off income for services, a finding that has significant equity implications in terms of allocating scarce public services and achieving universal water access.Town Water Supply and Sanitation,Water and Industry,Economic Theory&Research,Water Use,Water Supply and Sanitation Governance and Institutions
Neutron, electron and X-ray scattering investigation of Cr1-xVx near Quantum Criticality
The weakness of electron-electron correlations in the itinerant
antiferromagnet Cr doped with V has long been considered the reason that
neither new collective electronic states or even non Fermi liquid behaviour are
observed when antiferromagnetism in CrV is suppressed to zero
temperature. We present the results of neutron and electron diffraction
measurements of several lightly doped single crystals of CrV in
which the archtypal spin density wave instability is progressively suppressed
as the V content increases, freeing the nesting-prone Fermi surface for a new
striped charge instability that occurs at x=0.037. This novel nesting
driven instability relieves the entropy accumulation associated with the
suppression of the spin density wave and avoids the formation of a quantum
critical point by stabilising a new type of charge order at temperatures in
excess of 400 K. Restructuring of the Fermi surface near quantum critical
points is a feature found in materials as diverse as heavy fermions, high
temperature copper oxide superconductors and now even elemental metals such as
Cr.Comment: 6 pages, 6 figures. Accepted to Physical Review
MHV Lagrangian for N=4 Super Yang-Mills
Here we formulate two field redefinitions for N=4 Super Yang-Mills in light
cone superspace that generates only MHV vertices in the new Lagrangian. After
careful consideration of the S-matrix equivalence theorem, we see that only the
canonical transformation gives the MHV Lagrangian that would correspond to the
CSW expansion. Being in superspace, it is easier to analyse the equivalence
theorem at loop level. We calculate the on shell amplitude for 4pt
MHV in the new lagrangian and
show that it reproduces the previously known form. We also briefly discuss the
relationship with the off-shell continuation prescription of CSW.Comment: 17 pages 4 figures, 2 sections and several references added typo
correcte
Discomfort and agitation in older adults with dementia
<p>Abstract</p> <p>Background</p> <p>A majority of patients with dementia present behavioral and psychological symptoms, such as agitation, which may increase their suffering, be difficult to manage by caregivers, and precipitate institutionalization. Although internal factors, such as discomfort, may be associated with agitation in patients with dementia, little research has examined this question. The goal of this study is to document the relationship between discomfort and agitation (including agitation subtypes) in older adults suffering from dementia.</p> <p>Methods</p> <p>This correlational study used a cross-sectional design. Registered nurses (RNs) provided data on forty-nine residents from three long-term facilities. Discomfort, agitation, level of disability in performing activities of daily living (ADL), and severity of dementia were measured by RNs who were well acquainted with the residents, using the Discomfort Scale for patients with Dementia of the Alzheimer Type, the Cohen-Mansfield Agitation Inventory, the ADL subscale of the Functional Autonomy Measurement System, and the Functional Assessment Staging, respectively. RNs were given two weeks to complete and return all scales (i.e., the Cohen-Mansfield Agitation Inventory was completed at the end of the two weeks and all other scales were answered during this period). Other descriptive variables were obtained from the residents' medical file or care plan.</p> <p>Results</p> <p>Hierarchical multiple regression analyses controlling for residents' characteristics (sex, severity of dementia, and disability) show that discomfort explains a significant share of the variance in overall agitation (28%, <it>p </it>< 0.001), non aggressive physical behavior (18%, <it>p </it>< 0.01) and verbally agitated behavior (30%, <it>p </it>< 0.001). No significant relationship is observed between discomfort and aggressive behavior but the power to detect this specific relationship was low.</p> <p>Conclusion</p> <p>Our findings provide further evidence of the association between discomfort and agitation in persons with dementia and reveal that this association is particularly strong for verbally agitated behavior and non aggressive physical behavior.</p
Techniques For Injection Of Pre-Charaterized Dust Into The Scrape Off Layer Of Fusion Plasma
Introduction of micron-sized dust into the scrape-off layer (SOL) of a plasma has recently found many applications aimed primarily at determining dust behavior in future fusion reactors. The dust particles are typically composed of materials intrinsic to a fusion reactor. On DIII-D and TEXTOR carbon dust has been introduced into the SOL using a probe inserted from below into the divertor region. On NSTX, both Li and tungsten dust have been dropped from the top of the machine into the SOL throughout the duration of a discharge, by utilizing a vibrating piezoelectric based particle dropper. The original particle dropper was developed to inject passivated Li powder {approx} 40 {mu}m in diameter into the SOL to enhance plasma performance. A simplified version of the dropper was developed to introduce trace amounts of tungsten powder for only a few discharges, thus not requiring a large powder reservoir. The particles emit visible light from plasma interactions and can be tracked by either spectroscopic means or by fast frame rate visible cameras. This data can then be compared with dust transport codes such as DUSTT to make predictions of dust behavior in next-step devices such as ITER. For complete modeling results, it is desired to be able to inject pre-characterized dust particles in the SOL at various known poloidal locations, including near the vessel midplane. Purely mechanical methods of injecting particles are presently being studied using a modified piezoelectric-based powder dropper as a particle source and one of several piezo-based transducers to deflect the particles into the SOL. Vibrating piezo fans operating at 60 Hz with a deflection of {+-}2.5 cm can impart a significant horizontal boost in velocity. The highest injection velocities are expected from rotating paddle wheels capable of injecting particles at 10's of meters per second depending primarily on the rotation velocity and diameter of the wheel. Several injection concepts have been tested and will be discussed below
The No-Triangle Hypothesis for N=8 Supergravity
We study the perturbative expansion of N=8 supergravity in four dimensions
from the viewpoint of the ``no-triangle'' hypothesis, which states that
one-loop graviton amplitudes in N=8 supergravity only contain scalar box
integral functions. Our computations constitute a direct proof at six-points
and support the no-triangle conjecture for seven-point amplitudes and beyond.Comment: 43page
Production, characterization, and antigen specificity of recombinant 62-71-3, a candidate monoclonal antibody for rabies prophylaxis in humans
Rabies kills many people throughout the developing world every year. The murine monoclonal antibody (mAb) 62-71-3 was recently identified for its potential application in rabies postexposure prophylaxis (PEP). The purpose here was to establish a plant-based production system for a chimeric mouse-human version of mAb 62-71-3, to characterize the recombinant antibody and investigate at a molecular level its interaction with rabies virus glycoprotein. Chimeric 62-71-3 was successfully expressed in Nicotiana benthamiana. Glycosylation was analyzed by mass spectroscopy; functionality was confirmed by antigen ELISA, as well as rabies and pseudotype virus neutralization. Epitope characterization was performed using pseudotype virus expressing mutagenized rabies glycoproteins. Purified mAb demonstrated potent viral neutralization at 500 IU/mg. A critical role for antigenic site I of the glycoprotein, as well as for two specific amino acid residues (K226 and G229) within site I, was identified with regard to mAb 62-71-3 neutralization. Pseudotype viruses expressing glycoprotein from lyssaviruses known not to be neutralized by this antibody were the controls. The results provide the molecular rationale for developing 62-71-3 mAb for rabies PEP; they also establish the basis for developing an inexpensive plant-based antibody product to benefit low-income families in developing countries.—Both, L., van Dolleweerd, C., Wright, E., Banyard, A. C., Bulmer-Thomas, B., Selden, D., Altmann, F., Fooks, A. R., Ma, J. K.-C. Production, characterization, and antigen specificity of recombinant 62-71-3, a candidate monoclonal antibody for rabies prophylaxis in humans
Local Spacetime Physics from the Grassmannian
A duality has recently been conjectured between all leading singularities of
n-particle N^(k-2)MHV scattering amplitudes in N=4 SYM and the residues of a
contour integral with a natural measure over the Grassmannian G(k,n). In this
note we show that a simple contour deformation converts the sum of Grassmannian
residues associated with the BCFW expansion of NMHV tree amplitudes to the CSW
expansion of the same amplitude. We propose that for general k the same
deformation yields the (k-2) parameter Risager expansion. We establish this
equivalence for all MHV-bar amplitudes and show that the Risager degrees of
freedom are non-trivially determined by the GL(k-2) "gauge" degrees of freedom
in the Grassmannian. The Risager expansion is known to recursively construct
the CSW expansion for all tree amplitudes, and given that the CSW expansion
follows directly from the (super) Yang-Mills Lagrangian in light-cone gauge,
this contour deformation allows us to directly see the emergence of local
space-time physics from the Grassmannian.Comment: 22 pages, 13 figures; v2: minor updates, typos correcte
Yang-Mills Theory In Axial Gauge
The Yang-Mills functional integral is studied in an axial variant of 't
Hooft's maximal Abelian gauge. In this gauge Gau\ss ' law can be completely
resolved resulting in a description in terms of unconstrained variables.
Compared to previous work along this line starting with work of Goldstone and
Jackiw one ends up here with half as many integration variables, besides a
field living in the Cartan subgroup of the gauge group and in D-1 dimension.
The latter is of particular relevance for the infrared behaviour of the theory.
Keeping only this variable we calculate the Wilson loop and find an area law.Comment: 43 pages REVTeX, 6 figure
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