861 research outputs found
Giant Gravitons with NSNS B field
We study the motion of a D(8-p)-brane probe in the background created by a
stack of non-threshold (D(p-2), Dp) bound states for . The brane
probe and the branes of the background have two common directions. We show that
for a particular value of the worldvolume gauge field there exist
configurations of the probe brane which behave as massless particles and can be
interpreted as gravitons blown up into a fuzzy sphere and a noncommutative
plane. We check this behaviour by studying the motion and energy of the brane
and by determining how supersymmetry is broken by the probe as it moves under
the action of the background.Comment: 24 pages, LaTe
Flux Stabilization of D-branes in a non-threshold bound state background
We study some configurations of brane probes which are partially wrapped on
spheres transverse to a stack of non-threshold bound states. The latter are
represented by the corresponding supergravity background. Two cases are
studied: D(10-p)-branes in the background of (D(p-2), Dp) bound states and
D(8-p)-branes in the (NS5, Dp) geometry. By using suitable flux quantization
rules of the worldvolume gauge field, we determine the stable configurations of
the probe. The analysis of the energy and supersymmetry of these configurations
reveals that they can be interpreted as bound states of lower dimensional
objects polarized into a D-brane.Comment: 11 pages, LaTe
How does carer management style influence the performance of activities of daily living in people with dementia?
INTRODUCTION: People with Dementia (PwD)ās performance of activities of daily living (ADLs) has been associated with apathy, cognitive deficits, carersā depression and burden. However, it is not known if the carersā management style affects ADL performance, particularly alongside PwDās cognitive deficits and apathy. Thus, the aim of this study was to explore the contribution of intrinsic (cognition, apathy) and extrinsic (carer management styles) dementia factors to ADL performance.
METHODS: PwD (n=143) were assessed on global cognition (ACE-III); apathy (CBI-R); ADLs (Disability Assessment for Dementia-DAD). Carersā (n=143) criticism, encouragement and active-management styles were assessed with the Dementia Management Strategy Scale (DMSS). Multiple linear regression analysis investigated contributions of carer styles, cognition, apathy (independent variables) on ADLs (dependent variable).
RESULTS: The best model explaining the variance of the DAD scores included cognition (Ī² =0.413, t(142)=4.463, p=0.001), apathy (Ī² =-0.365, t(142)=-5.556, p=0.001), carer criticism (Ī² =-0.326, t(142)=-2.479, p=0.014) and carer encouragement styles (Ī² =0.402, t(142)=2.941, p=0.004) accounting for 40% of the variance of the DAD scores.
CONCLUSIONS: This novel study demonstrated that PwDās level of apathy and the carerās use of criticism negatively affected ADL performance while PwDās cognitive abilities and carer encouragement style improved ADL performance. These findings have critical implications for the development of novel multi-component non-pharmacological interventions to maintain function and delay disease progression in dementia, as well as direct relevance to current carers and families
Worldvolume Dynamics of D-branes in a D-brane Background
We study the embedding of D(8-p)-branes in the background geometry of parallel Dp-branes for . The D(8-p)-brane is extended along the directions orthogonal to the Dp-branes of the background. The D(8-p)-brane configuration is determined by its Dirac-Born-Infeld plus Wess-Zumino-Witten action. We find a BPS condition which solves the equation of motion. The analytical solution of the BPS equation for the near-horizon and asymptotically flat geometries is given. The embeddings we obtain represent branes joined by tubes. By analyzing the energy of these tubes we conclude that they can be regarded as bundles of fundamental strings. Our solution provides an explicit realization of the Hanany-Witten effect. When the solution of the BPS equation must be considered separately and, in general, the embeddings of the D2-branes do not admit the same interpretation as in the case
EvaluaciĆ³n del comportamiento de las fĆ”bricas de ladrillos de tejar y argamasa debido a la humedad que asciende por capilaridad
For a better understanding of the behaviour of old brick masonry in facing the rising damp problem, multiple tests were made in the laboratory: water absorption, moisture content, apparent porosity, temperature and thermal camera imaging on brick masonry and its components: brick and mortar. This has allowed us to determine which of the previous tests is the best in predicting the behaviour of a real wall. In addition, the tests have also helped in defining a process to evaluate the moisture content of walls in a buildings, which is important for heritage restoration projects.Para un mejor conocimiento del comportamiento de las fĆ”bricas antiguas de ladrillo frente a la ascensiĆ³n capilar de agua, se han realizado en laboratorio ensayos de absorciĆ³n de agua, de contenido de humedad, de porosidad aparente, de temperatura e imĆ”genes con cĆ”mara termogrĆ”fica sobre muros de fĆ”brica y sus materiales componentes: ladrillo y argamasa. Ello ha permitido inferir cuĆ”l es el ensayo realizado a los ladrillos que mejor predice el comportamiento del muro real. TambiĆ©n ha permitido definir un procedimiento para evaluar el contenido de humedad de fĆ”bricas existentes, importante para los proyectos de restauraciĆ³n del patrimonio construido
Semiochemical exploitation of host-associated cues by seven Melittobia parasitoid species: Behavioral and phylogenetic implications
Chemical compounds (infochemicals or semiochemicals) play an important role both in intra-specific and inter-specific communication. For example, chemical cues appear to play a key role in the host selection process adopted by insect parasitoids. In recent years significant advances have been made in order to understand the chemical ecology of insect parasitoids. However, little information is available about the evolution of semiochemical use in the host location process of insect parasitoids. Here we investigated the strategy adopted by seven closely related parasitoid species in the genus Melittobia when foraging for four different suitable hosts. By using an integrated approach that combined olfactometer bioassays and phylogenetic investigations, we found that: (1) exploitation of host-derived semiochemicals is widespread in the Melittobia genus; (2) there is specificity of attraction toward the different host species tested; in particular, the early-branching species in the Melittobia genus are attracted to odors associated with leaf cutting bees (Megachile rotundata) whereas the most-diverged species are attracted to odors associated with solitary mud dauber wasps (Trypoxyilon politum). Regardless of the phylogenetic relationships, no Melittobia species exhibited attraction toward odors of factitious laboratory hosts (i.e., the flesh fly Sarcophaga bullata). Interestingly, five Melittobia species are also attracted by odors associated with honeybees hosts which indicate that these parasitoids could be potential pests of honeybees. Our study shed light on the host location within the Melittobia genus and represents a first attempt to understand semiochemical use in an evolutionary perspective in the context of parasitoids' foraging behavior
Deforming baryons into confining strings
We find explicit probe D3-brane solutions in the infrared of the
Maldacena-Nunez background. The solutions describe deformed baryon vertices: q
external quarks are separated in spacetime from the remaining N-q. As the
separation is taken to infinity we recover known solutions describing infinite
confining strings in gauge theory. We present results for the
mass of finite confining strings as a function of length. We also find probe
D2-brane solutions in a confining type IIA geometry, the reduction of a G_2
holonomy M theory background. The relation between these deformed baryons and
confining strings is not as straightforward.Comment: 1+13 pages. LaTeX. 3 Figures. Factor of 2N fixed to N for the IIA
background. Minor changes to tex
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