1,023 research outputs found
Хліб: семантика в контексті народного етикету Середнього Полісся
У статті представлено дослідження міфологічних уявлень, пов’язаних з хлібом. Розглянуто особливості функціонування, семантизації цього культурного явища та його номінацію.Статья представляет исследование мифологических представлений, связанных с хлебом. Рассмотрено особенности функционирования, семантизации этого культурного явления и его номинацию.The article presents the study of the mythological presentations, what a connected with bread. The considered particularity of the operation, semantization this cultural phenomena and its nomination
An Infinite-Dimensional Family of Black-Hole Microstate Geometries
We construct the first explicit, smooth, horizonless black-hole microstate
geometry whose moduli space is described by an arbitrary function of one
variable and is thus infinite-dimensional. This is achieved by constructing the
scalar Green function on a simple D6 anti-D6 background, and using this Green
function to obtain the fully back-reacted solution for a supertube with varying
charge density in this background. We show that this supertube can store
parametrically more entropy than in flat space, confirming the entropy
enhancement mechanism that was predicted using brane probes. We also show that
all the local properties of the fully back-reacted solution can, in fact, be
obtained using the DBI action of an appropriate brane probe. In particular, the
supergravity and the DBI analysis yield identical functional bubble equations
that govern the relative locations of the centers. This indicates that there is
a non-renormalization theorem that protects these functional equations as one
moves in moduli space. Our construction creates configurations that are beyond
the scope of recent arguments that appear to put strong limits on the entropy
that can be found in smooth supergravity solutions.Comment: 46 pages, 1 figure, LaTe
Quantum Current Algebra for the Superstring
The sigma model describing the dynamics of the superstring in the background can be constructed using the coset
. A basic set of operators in this two
dimensional conformal field theory is composed by the left invariant currents.
Since these currents are not (anti) holomorphic, their OPE's is not determined
by symmetry principles and its computation should be performed perturbatively.
Using the pure spinor sigma model for this background, we compute the one-loop
correction to these OPE's. We also compute the OPE's of the left invariant
currents with the energy momentum tensor at tree level and one loop.Comment: 28 pages, 12 figures, v2: typos corrected
Kerr/CFT, dipole theories and nonrelativistic CFTs
We study solutions of type IIB supergravity which are SL(2,R) x SU(2) x
U(1)^2 invariant deformations of AdS_3 x S^3 x K3 and take the form of products
of self-dual spacelike warped AdS_3 and a deformed three-sphere. One of these
backgrounds has been recently argued to be relevant for a derivation of
Kerr/CFT from string theory, whereas the remaining ones are holographic duals
of two-dimensional dipole theories and their S-duals. We show that each of
these backgrounds is holographically dual to a deformation of the DLCQ of the
D1-D5 CFT by a specific supersymmetric (1,2) operator, which we write down
explicitly in terms of twist operators at the free orbifold point. The
deforming operator is argued to be exactly marginal with respect to the
zero-dimensional nonrelativistic conformal (or Schroedinger) group - which is
simply SL(2,R)_L x U(1)_R. Moreover, in the supergravity limit of large N and
strong coupling, no other single-trace operators are turned on. We thus propose
that the field theory duals to the backgrounds of interest are nonrelativistic
CFTs defined by adding the single Schroedinger-invariant (1,2) operator
mentioned above to the original CFT action. Our analysis indicates that the
rotating extremal black holes we study are best thought of as finite
right-moving temperature (non-supersymmetric) states in the above-defined
supersymmetric nonrelativistic CFT and hints towards a more general connection
between Kerr/CFT and two-dimensional non-relativistic CFTs.Comment: 48+8 pages, 4 figures; minor corrections and references adde
Hamilton-Jacobi Renormalization for Lifshitz Spacetime
Just like AdS spacetimes, Lifshitz spacetimes require counterterms in order
to make the on-shell value of the bulk action finite. We study these
counterterms using the Hamilton-Jacobi method. Rather than imposing boundary
conditions from the start, we will derive suitable boundary conditions by
requiring that divergences can be canceled using only local counterterms. We
will demonstrate in examples that this procedure indeed leads to a finite bulk
action while at the same time it determines the asymptotic behavior of the
fields. This puts more substance to the belief that Lifshitz spacetimes are
dual to well-behaved field theories. As a byproduct, we will find the analogue
of the conformal anomaly for Lifshitz spacetimes.Comment: 27 pages; minor improvements, references added, published versio
Towards molecular electronics with large-area molecular junctions
Electronic transport through single molecules has been studied extensively by academic(1-8) and industrial(9,10) research groups. Discrete tunnel junctions, or molecular diodes, have been reported using scanning probes(11,12), break junctions(13,14), metallic crossbars(6) and nanopores(8,15). For technological applications, molecular tunnel junctions must be reliable, stable and reproducible. The conductance per molecule, however, typically varies by many orders of magnitude(5). Self-assembled monolayers (SAMs) may offer a promising route to the fabrication of reliable devices, and charge transport through SAMs of alkanethiols within nanopores is well understood, with non-resonant tunnelling dominating the transport mechanism(8). Unfortunately, electrical shorts in SAMs are often formed upon vapour deposition of the top electrode(16-18), which limits the diameter of the nanopore diodes to about 45 nm. Here we demonstrate a method to manufacture molecular junctions with diameters up to 100 mu m with high yields (>95 per cent). The junctions show excellent stability and reproducibility, and the conductance per unit area is similar to that obtained for benchmark nanopore diodes. Our technique involves processing the molecular junctions in the holes of a lithographically patterned photoresist, and then inserting a conducting polymer interlayer between the SAM and the metal top electrode. This simple approach is potentially low-cost and could pave the way for practical molecular electronics
Adaptive Filtering Enhances Information Transmission in Visual Cortex
Sensory neuroscience seeks to understand how the brain encodes natural
environments. However, neural coding has largely been studied using simplified
stimuli. In order to assess whether the brain's coding strategy depend on the
stimulus ensemble, we apply a new information-theoretic method that allows
unbiased calculation of neural filters (receptive fields) from responses to
natural scenes or other complex signals with strong multipoint correlations. In
the cat primary visual cortex we compare responses to natural inputs with those
to noise inputs matched for luminance and contrast. We find that neural filters
adaptively change with the input ensemble so as to increase the information
carried by the neural response about the filtered stimulus. Adaptation affects
the spatial frequency composition of the filter, enhancing sensitivity to
under-represented frequencies in agreement with optimal encoding arguments.
Adaptation occurs over 40 s to many minutes, longer than most previously
reported forms of adaptation.Comment: 20 pages, 11 figures, includes supplementary informatio
Re-evaluating a vision-related quality of life questionnaire with item response theory (IRT) and differential item functioning (DIF) analyses
Background: For the Low Vision Quality Of Life questionnaire (LVQOL) it is unknown whether the psychometric properties are satisfactory when an item response theory (IRT) perspective is considered. This study evaluates some essential psychometric properties of the LVQOL questionnaire in an IRT model, and investigates differential item functioning (DIF). Methods: Cross-sectional data were used from an observational study among visually-impaired patients (n = 296). Calibration was performed for every dimension of the LVQOL in the graded response model. Item goodness-of-fit was assessed with the S-X2-test. DIF was assessed on relevant background variables (i.e. age, gender, visual acuity, eye condition, rehabilitation type and administration type) with likelihood-ratio tests for DIF. The magnitude of DIF was interpreted by assessing the largest difference in expected scores between subgroups. Measurement precision was assessed by presenting test information curves; reliability with the index of subject separation. Results: All items of the LVQOL dimensions fitted the model. There was significant DIF on several items. For two items the maximum difference between expected scores exceeded one point, and DIF was found on multiple relevant background variables. Item 1 ‘Vision in general’ from the “Adjustment” dimension and item 24 ‘Using tools’ from the “Reading and fine work” dimension were removed. Test information was highest for the “Reading and fine work” dimension. Indices for subject separation ranged from 0.83 to 0.94. Conclusions: The items of the LVQOL showed satisfactory item fit to the graded response model; however, two items were removed because of DIF. The adapted LVQOL with 21 items is DIF-free and therefore seems highly appropriate for use in heterogeneous populations of visually impaired patients. (aut.ref.
Black-hole entropy from supergravity superstrata states
This work of JdB was supported in part by the Foundation of Fundamental Research on Matter (FOM) and by an NWO Spinoza grant. The work of MS was
supported in part by Grant-in-Aid for Young Scientists (B) 24740159 from the Japan Society for the Promotion of Science
(JSPS)
Enhancing return-to-work in cancer patients, development of an intervention and design of a randomised controlled trial
ABSTRACT: BACKGROUND: Compared to healthy controls, cancer patients have a higher risk of unemployment, which has negative social and economic impacts on the patients and on society at large. Therefore, return-to-work of cancer patients needs to be improved by way of an intervention. The objective is to describe the development and content of a work-directed intervention to enhance return-to-work in cancer patients and to explain the study design used for evaluating the effectiveness of the intervention. METHODS: Development and content of the intervention The work-directed intervention has been developed based on a systematic literature review of work-directed interventions for cancer patients, factors reported by cancer survivors as helping or hindering their return-to-work, focus group and interview data for cancer patients, health care professionals, and supervisors, and vocational rehabilitation literature. The work-directed intervention consists of: 1) 4 meetings with a nurse at the treating hospital department to start early vocational rehabilitation, 2) 1 meeting with the participant, occupational physician, and supervisor to make a return-to-work plan, and 3) letters from the treating physician to the occupational physician to enhance communication. Study design to evaluate the intervention The treating physician or nurse recruits patients before the start of initial treatment. Patients are eligible when they have a primary diagnosis of cancer, will be treated with curative intent, are employed at the time of diagnosis, are on sick leave, and are between 18 and 60 years old. After the patients have given informed consent and have filled out a baseline questionnaire, they are randomised to either the control group or to the intervention group and receive either care as usual or the work-directed intervention, respectively. Primary outcomes are return-to-work and quality of life. The feasibility of the intervention and direct and indirect costs will be determined. Outcomes will be assessed by a questionnaire at baseline and at 6, 12, 18, and 24 months after baseline. DISCUSSION: This study will provide information about the effectiveness of a work-directed intervention for cancer patients. The intention is to implement the intervention in normal care if it has been shown effective. Trial registration: NTR165
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