134 research outputs found

    Weak-Interacting Holographic QCD

    Full text link
    We propose a simple prescription for including low-energy weak-interactions into the framework of holographic QCD, based on the standard AdS/CFT dictionary of double-trace deformations. As our proposal enables us to calculate various electro-weak observables involving strongly coupled QCD, it opens a new perspective on phenomenological applications of holographic QCD. We illustrate efficiency and usefulness of our method by performing a few exemplar calculations; neutron beta decay, charged pion weak decay, and meson-nucleon parity non-conserving (PNC) couplings. The idea is general enough to be implemented in both Sakai-Sugimoto as well as Hard/Soft Wall models.Comment: 18 pages, v3: submitted to PL

    Holographic Description of Glueball and Baryon in Noncommutative Dipole Gauge Theory

    Full text link
    We study the glueball spectrum in the supersymmetric and non-supersymmetric 4D non-commutative dipole gauge theory from the holographic description. We adopt the semiclassical WKB approximation to solve the dilaton and antisymmetric tensor field equations on the dual supergravity backgrounds to find the analytic formula of the spectrum of 0++0^{++} and 11^{--} glueballs, respectively. In the supersymmetric theory we see that the dipole length plays the intrinsic scale which reflects the discrete spectrum therein. In the non-supersymmetric theory, the temperature (or the radius of compactification) in there will now play the intrinsic scale and we see that the dipole has an effect to produce attractive force between the gluons within the glueball. We also study the confining force between the quarks within the baryon via strings that hang into the dipole deformed AdS geometry and see that the dipole could also produce an attractive force between the quarks. In particular, we find that the baryon has two phases in which a big baryon is dual to the static string while a small baryon is described by a moving dual string .Comment: Latex 18 page

    Nuclear matter to strange matter transition in holographic QCD

    Full text link
    We construct a simple holographic QCD model to study nuclear matter to strange matter transition. The interaction of dense medium and hadrons is taken care of by imposing the force balancing condition for stable D4/D6/D6 configuration. By considering the intermediate and light flavor branes interacting with baryon vertex homogeneously distributed along R^3 space and requesting the energy minimization, we find that there is a well defined transition density as a function of current quark mass. We also find that as density goes up very high, intermediate (or heavy) and light quarks populate equally as expected from the Pauli principle. In this sense, the effect of the Pauli principle is realized as dynamics of D-branes.Comment: 13 pages, 14 figure

    Variability of the lateral femoral cutaneous nerve: An anatomic basis for planning safe surgical approaches

    Full text link
    Current surgical assumptions identify the lateral femoral cutaneous nerve (LFCN) running just under the inguinal ligament two fingerbreadths medial to the anterior superior iliac spine (ASIS). On the basis of the increasing incidence of Meralgia Paresthetica associated with various surgical procedures, it is clear that surgeons are relying on an inadequate description of the nerve's course. This study provides a better understanding of the variability of the LFCN with regards to its relationship to the ASIS and the depth at which it passes deep to the inguinal ligament. A total of 35 bodies were examined yielding 65 sets of data. Dissections were performed on 26 formalin fixed cadavers and 9 fresh morgue specimens. Measurements and calculations were made with regard to the distance from the LFCN to the ASIS along the inguinal ligament, the depth of the LFCN as it crossed the inguinal ligament, and the length of the inguinal ligament. The LFCN was observed to cross the inguinal ligament 1.4 ± 0.4 cm medial to the ASIS with a standard deviation of 1.5 cm. The LFCN traversed the inguinal ligament 1.0 ± 0.1 cm deep to the ligament with a standard deviation of 0.6 cm. The LFCN runs approximately one fingerbreadth medial to the ASIS. The nerve may be found far more medial or lateral than expected with several distinct branching patterns. In addition, the LFCN crosses deeper to the inguinal ligament than previously described in the literature, with a high variability of depth between specimens. Clin. Anat. 23:304–311, 2010. © 2010 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69161/1/20943_ftp.pd

    Cumulative effects matter: multi-brood responses of Daphnia to hypoxia

    Get PDF
    Periods of hypoxia lasting up to weeks are now anticipated in fresh waters, owing to anthropogenic influences. However, the cumulative effects of hypoxia on Daphnia, over multiple broods, have received virtually no attention, and to establish and evaluate such responses there is a need to make measurements over a wide range of oxygen concentrations, potentially revealing non-linear patterns. We predict that the effect of hypoxia on growth, survival and fecundity (i.e., production of new individuals) of Daphnia will increase over multiple broods, and with increasing oxygen these responses will approach asymptotic maxima, following a rectangular hyperbolic response. Daphnia similoides were exposed to 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 and 8.0 mg oxygen L−1. To determine effects on the first brood we examined: number of offspring; time to the first eggs; time to the first brood and size of the female at the first eggs and the first brood. To determine cumulative effects of oxygen over multiple broods (up to 8 broods over 21 days), we measured: total number of offspring produced by a female; survival time and total number of moults and broods. To investigate how the cumulative effects arose over the multiple broods, we examined the number of offspring per brood in each brood over eight broods. To assess treatment effects and indicate responses, functions were fit to data using the most parsimonious function that reflected trends in the data. Measurements associated with a single brood responded linearly, or not at all, with changing oxygen concentration, whereas measurements made over the 21 days followed a rectangular hyperbolic response, increasing to an asymptote as oxygen increased. For the first brood, as oxygen concentration was raised from 1 to 8 mg L−1 the number of offspring produced and the time required to produce the brood were not affected; the time required to produce eggs decreased ˜0.3-fold; and the size of individuals at the time when the eggs and the brood were produced increased ˜0.1-fold. Over the 21 days, between 1 and 8 mg L−1 the total number of offspring increased ˜3.4-fold; individual survival and the number of moults increased ˜2-fold, and the number of broods increased ˜1-fold. For single-brood responses, there was no effect of decreasing oxygen levels on the number of offspring in the first brood, but there were negative effects on the second-to-fourth broods; the number of offspring in the remaining broods was not significantly related to oxygen levels, as there were fewer data at low levels due to poor survival. We conclude that assessments of Daphnia demographics should not rely on estimates of the effect of oxygen concentration on single broods. Instead, studies should consider cumulative changes over multiple broods. Following our approach, researchers may now explore the impacts of hypoxia on congeners and other zooplankton, and investigate the mechanisms associated with multi-brood responses

    Multiphoton Quantum Optics and Quantum State Engineering

    Full text link
    We present a review of theoretical and experimental aspects of multiphoton quantum optics. Multiphoton processes occur and are important for many aspects of matter-radiation interactions that include the efficient ionization of atoms and molecules, and, more generally, atomic transition mechanisms; system-environment couplings and dissipative quantum dynamics; laser physics, optical parametric processes, and interferometry. A single review cannot account for all aspects of such an enormously vast subject. Here we choose to concentrate our attention on parametric processes in nonlinear media, with special emphasis on the engineering of nonclassical states of photons and atoms. We present a detailed analysis of the methods and techniques for the production of genuinely quantum multiphoton processes in nonlinear media, and the corresponding models of multiphoton effective interactions. We review existing proposals for the classification, engineering, and manipulation of nonclassical states, including Fock states, macroscopic superposition states, and multiphoton generalized coherent states. We introduce and discuss the structure of canonical multiphoton quantum optics and the associated one- and two-mode canonical multiphoton squeezed states. This framework provides a consistent multiphoton generalization of two-photon quantum optics and a consistent Hamiltonian description of multiphoton processes associated to higher-order nonlinearities. Finally, we discuss very recent advances that by combining linear and nonlinear optical devices allow to realize multiphoton entangled states of the electromnagnetic field, that are relevant for applications to efficient quantum computation, quantum teleportation, and related problems in quantum communication and information.Comment: 198 pages, 36 eps figure

    Polycystic ovary syndrome

    Get PDF
    The document attached has been archived with permission from the editor of the Medical Journal of Australia. An external link to the publisher’s copy is included.Polycystic ovary syndrome (PCOS) affects 5-20% of women of reproductive age worldwide. The condition is characterized by hyperandrogenism, ovulatory dysfunction and polycystic ovarian morphology (PCOM) - with excessive androgen production by the ovaries being a key feature of PCOS. Metabolic dysfunction characterized by insulin resistance and compensatory hyperinsulinaemia is evident in the vast majority of affected individuals. PCOS increases the risk for type 2 diabetes mellitus, gestational diabetes and other pregnancy-related complications, venous thromboembolism, cerebrovascular and cardiovascular events and endometrial cancer. PCOS is a diagnosis of exclusion, based primarily on the presence of hyperandrogenism, ovulatory dysfunction and PCOM. Treatment should be tailored to the complaints and needs of the patient and involves targeting metabolic abnormalities through lifestyle changes, medication and potentially surgery for the prevention and management of excess weight, androgen suppression and/or blockade, endometrial protection, reproductive therapy and the detection and treatment of psychological features. This Primer summarizes the current state of knowledge regarding the epidemiology, mechanisms and pathophysiology, diagnosis, screening and prevention, management and future investigational directions of the disorder.Robert J Norman, Ruijin Wu and Marcin T Stankiewic

    Reproducibility in the absence of selective reporting : An illustration from large-scale brain asymmetry research

    Get PDF
    Altres ajuts: Max Planck Society (Germany).The problem of poor reproducibility of scientific findings has received much attention over recent years, in a variety of fields including psychology and neuroscience. The problem has been partly attributed to publication bias and unwanted practices such as p-hacking. Low statistical power in individual studies is also understood to be an important factor. In a recent multisite collaborative study, we mapped brain anatomical left-right asymmetries for regional measures of surface area and cortical thickness, in 99 MRI datasets from around the world, for a total of over 17,000 participants. In the present study, we revisited these hemispheric effects from the perspective of reproducibility. Within each dataset, we considered that an effect had been reproduced when it matched the meta-analytic effect from the 98 other datasets, in terms of effect direction and significance threshold. In this sense, the results within each dataset were viewed as coming from separate studies in an "ideal publishing environment," that is, free from selective reporting and p hacking. We found an average reproducibility rate of 63.2% (SD = 22.9%, min = 22.2%, max = 97.0%). As expected, reproducibility was higher for larger effects and in larger datasets. Reproducibility was not obviously related to the age of participants, scanner field strength, FreeSurfer software version, cortical regional measurement reliability, or regional size. These findings constitute an empirical illustration of reproducibility in the absence of publication bias or p hacking, when assessing realistic biological effects in heterogeneous neuroscience data, and given typically-used sample sizes
    corecore