234 research outputs found
Running with Rugby Balls: Bulk Renormalization of Codimension-2 Branes
We compute how one-loop bulk effects renormalize both bulk and brane
effective interactions for geometries sourced by codimension-two branes. We do
so by explicitly integrating out spin-zero, -half and -one particles in
6-dimensional Einstein-Maxwell-Scalar theories compactified to 4 dimensions on
a flux-stabilized 2D geometry. (Our methods apply equally well for D dimensions
compactified to D-2 dimensions, although our explicit formulae do not capture
all divergences when D>6.) The renormalization of bulk interactions are
independent of the boundary conditions assumed at the brane locations, and
reproduce standard heat-kernel calculations. Boundary conditions at any
particular brane do affect how bulk loops renormalize this brane's effective
action, but not the renormalization of other distant branes. Although we
explicitly compute our loops using a rugby ball geometry, because we follow
only UV effects our results apply more generally to any geometry containing
codimension-two sources with conical singularities. Our results have a variety
of uses, including calculating the UV sensitivity of one-loop vacuum energy
seen by observers localized on the brane. We show how these one-loop effects
combine in a surprising way with bulk back-reaction to give the complete
low-energy effective cosmological constant, and comment on the relevance of
this calculation to proposed applications of codimension-two 6D models to
solutions of the hierarchy and cosmological constant problems.Comment: 42 pages + appendices. This is the final version which appears in
JHE
Accidental SUSY: Enhanced Bulk Supersymmetry from Brane Back-reaction
We compute how bulk loops renormalize both bulk and brane effective
interactions for codimension-two branes in 6D gauged chiral supergravity, as
functions of the brane tension and brane-localized flux. We do so by explicitly
integrating out hyper- and gauge-multiplets in 6D gauged chiral supergravity
compactified to 4D on a flux-stabilized 2D rugby-ball geometry, specializing
the results of a companion paper, arXiv:1210.3753, to the supersymmetric case.
While the brane back-reaction generically breaks supersymmetry, we show that
the bulk supersymmetry can be preserved if the amount of brane-localized flux
is related in a specific BPS-like way to the brane tension, and verify that the
loop corrections to the brane curvature vanish in this special case. In these
systems it is the brane-bulk couplings that fix the size of the extra
dimensions, and we show that in some circumstances the bulk geometry
dynamically adjusts to ensure the supersymmetric BPS-like condition is
automatically satisfied. We investigate the robustness of this residual
supersymmetry to loops of non-supersymmetric matter on the branes, and show
that supersymmetry-breaking effects can enter only through effective brane-bulk
interactions involving at least two derivatives. We comment on the relevance of
this calculation to proposed applications of codimension-two 6D models to
solutions of the hierarchy and cosmological constant problems.Comment: 49 pages + appendices. This is the final version to appear in JHE
Cebos molusquicidas y molusquicidas lĂquidos para el control de Deroceras reticulatum (Pulmonata: Stylomatophora), plaga en el cultivo de colza
Oil seed rape (Brassica napus) under No Tillage (NT) represents an alternative in the current crop rotationsystems. Deroceras reticulatum “gray slug” is a one of the present pest in this crop under NT. The aim of thisstudy was to evaluate combined action bait and liquid Metaldehyde as an alternative strategy control of the specie. Laboratory and fields traits were carried out with the following treatments: control treatment without chemicals, chemical co tro (4 kg ha-1 of Metaldehyde 4 %), 3, 4 and 5 kg ha-1 combined action bait (Carbaryl8 % y Metaldehyde 4 %) and 1, 2 and 3 l ha-1 of liquid formulations (20 % Metaldehyde). The number of dead individuals of D. reticulatum and the number of damaged and undamaged plants were evaluated. In the laboratory,up to 3 days after application (DAA) it was observed higher control rates at all doses of liquid formulationthan all solids treatment. In both, solid and liquid treatments did not have doses effect. The proportion of damaged plants did not differ between treatments. In the field, at 2, 8 and 14 DAA liquid treatments showed lower control rates compared with the Metaldehyde baits and combined action bait. Both treatments solids and liquids were no effect of dose. The proportion of damaged plants was higher than that observed in laboratoryconditions. There were not observed differences in the proportion of damaged plants under chemical treatments and in the control with slugs. The application of liquid formulations may be carrying out close to crops sowing, while baits should be applied before sowing
Private hospital energy performance benchmarking using energy audit data: an Italian case study
The increased focus on energy efficiency, both at the national and international levels, has fostered the diffusion and development of specific energy consumption benchmarks for most relevant economic sectors. In this context, energy-intensive facilities, such as hospitals and health structures, represent a unique case. Indeed, despite the high energy consumption of these structures, scientific literature lacks the presence of adequate energy performance benchmarks, especially in regard to the European context. Thus, this study aimed at defining energy benchmark indicators for the Italian private healthcare sector using data collected from the Italian mandatory energy audits according to Art.8 EU Directive 27/2012. The benchmark indicators’ definition was made using a methodology proposed by the Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA). This methodology provided the calculation of specific energy performance indicators (EnPIs) by considering the global energy consumption of the different sites and the sector’s relevant variables. The results obtained were compared with those obtained from a consolidated but more complex methodology: the one envisaged by the Environmental Protection Agency. The results obtained allowed us to validate the reliability of the proposed methodology, as well as the validity and future usability of the calculated indicators. Relying on a significant database containing actual data from recent energy audits, this study was thus able to provide an up-to-date and reliable benchmark for the private healthcare sector
A Quantitative Study of In Vivo Protoporphyrin IX Fluorescence Build Up During Occlusive Treatment Phases
C L Campbell acknowledges financial support from an UK EPSRC PhD studentship (EP/K503162/1), the Alfred Stewart Trust, the Russell trust award, the Santander mobility award and the FAPESP CEPOF grant 2013/07276.Background: Topical photodynamic therapy (PDT) is a non-invasive light based therapy used to treat non-melanoma skin cancer (NMSC) and dysplasia. During PDT, the light sensitive molecule protoporphyrin IX (PpIX) is activated, resulting in the production of singlet oxygen, which subsequently leads to cell death. PpIX is metabolised from a topically applied pro-drug and the strong fluorescence signal associated with PpIX can be utilised as an indicator of the amount of PpIX present within the tumour tissue. In this work we measure the build up PpIX during the occlusive treatment phase and investigate how the PpIX production rate is affected by different lesion and patient characteristics. Methods : Fluorescence measurements were used to investigate the build up of PpIX within the tumour tissue during the 3 hour long occlusive treatment prior to irradiation. The study included in vivo measurements of 38 lesions from 38 individual patients. Actinic keratosis (AK) and basal cell carcinoma (BCC) were the lesion types included in this study. The resulting data from the study was analysed using generalised linear mixed effects models. Results : It was found that the surface fluorescence signal linearly increased with occlusive treatment time. The predictive models suggest that there is a significant difference in PpIX production between lesion location, however no significant difference is demonstrated between different lesion types, gender and skin type. Conclusions : The study extends and supports previous knowledge of PpIX production during the occlusive treatment phase.PostprintPeer reviewe
Hybrid compactifications and brane gravity in six dimensions
We consider a six-dimensional axisymmetric Einstein-Maxwell model of warped
braneworlds. The bulk is bounded by two branes, one of which is a conical
3-brane and the other is a 4-brane wrapped around the axis of symmetry. The
latter brane is assumed to be our universe. If the tension of the 3-brane is
fine-tuned, it folds the internal two-dimensional space in a narrow cone,
making sufficiently small the Kaluza-Klein circle of the 4-brane. An arbitrary
energy-momentum tensor can be accommodated on this ring-like 4-brane. We study
linear perturbations sourced by matter on the brane, and show that weak gravity
is apparently described by a four-dimensional scalar-tensor theory. The extra
scalar degree of freedom can be interpreted as the fluctuation of the internal
space volume (or that of the circumference of the ring), the effect of which
turns out to be suppressed at long distances. Consequently, four-dimensional
Einstein gravity is reproduced on the brane. We point out that as in the
Randall-Sundrum model, the brane bending mode is crucial for recovering the
four-dimensional tensor structure in this setup.Comment: 15 pages, 2 figures; v2: references added; v3: accepted for
publication in Class. Quant. Gra
Comparison between two packages for pectoral muscle removal on mammographic images
Background: Pectoral muscle removal is a fundamental preliminary step in computer-aided diagnosis systems for full-field digital mammography (FFDM). Currently, two open-source publicly available packages (LIBRA and OpenBreast) provide algorithms for pectoral muscle removal within Matlab environment. Purpose: To compare performance of the two packages on a single database of FFDM images. Methods: Only mediolateral oblique (MLO) FFDM was considered because of large presence of pectoral muscle on this type of projection. For obtaining ground truth, pectoral muscle has been manually segmented by two radiologists in consensus. Both LIBRA’s and OpenBreast’s removal performance with respect to ground truth were compared using Dice similarity coefficient and Cohen-kappa reliability coefficient; Wilcoxon signed-rank test has been used for assessing differences in performances; Kruskal–Wallis test has been used to verify possible dependence of the performance from the breast density or image laterality. Results: FFDMs from 168 consecutive women at our institution have been included in the study. Both LIBRA’s Dice-index and Cohen-kappa were significantly higher than OpenBreast (Wilcoxon signed-rank test P < 0.05). No dependence on breast density or laterality has been found (Kruskal–Wallis test P > 0.05). Conclusion: Libra has a better performance than OpenBreast in pectoral muscle delineation so that, although our study has not a direct clinical application, these results are useful in the choice of packages for the development of complex systems for computer-aided breast evaluation
Kicking the Rugby Ball: Perturbations of 6D Gauged Chiral Supergravity
We analyze the axially-symmetric scalar perturbations of 6D chiral gauged
supergravity compactified on the general warped geometries in the presence of
two source branes. We find all of the conical geometries are marginally stable
for normalizable perturbations (in disagreement with some recent calculations)
and the nonconical for regular perturbations, even though none of them are
supersymmetric (apart from the trivial Salam-Sezgin solution, for which there
are no source branes). The marginal direction is the one whose presence is
required by the classical scaling property of the field equations, and all
other modes have positive squared mass. In the special case of the conical
solutions, including (but not restricted to) the unwarped `rugby-ball'
solutions, we find closed-form expressions for the mode functions in terms of
Legendre and Hypergeometric functions. In so doing we show how to match the
asymptotic near-brane form for the solution to the physics of the source
branes, and thereby how to physically interpret perturbations which can be
singular at the brane positions.Comment: 21 pages + appendices, references adde
Quantum critical lines in holographic phases with (un)broken symmetry
All possible scaling IR asymptotics in homogeneous, translation invariant
holographic phases preserving or breaking a U(1) symmetry in the IR are
classified. Scale invariant geometries where the scalar extremizes its
effective potential are distinguished from hyperscaling violating geometries
where the scalar runs logarithmically. It is shown that the general critical
saddle-point solutions are characterized by three critical exponents (). Both exact solutions as well as leading behaviors are exhibited.
Using them, neutral or charged geometries realizing both fractionalized or
cohesive phases are found. The generic global IR picture emerging is that of
quantum critical lines, separated by quantum critical points which correspond
to the scale invariant solutions with a constant scalar.Comment: v3: 32+29 pages, 2 figures. Matches version published in JHEP.
Important addition of an exponent characterizing the IR scaling of the
electric potentia
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