Holographic DC conductivities from the open string metric

We study the DC conductivities of various holographic models using the open string metric (OSM), which is an effective metric geometrizing density and electromagnetic field effect. We propose a new way to compute the nonlinear conductivity using OSM. As far as the final conductivity formula is concerned, it is equivalent to the Karch-O'Bannon's real-action method. However, it yields a geometrical insight and technical simplifications. Especially, a real-action condition is interpreted as a regular geometry condition of OSM. As applications of the OSM method, we study several holographic models on the quantum Hall effect and strange metal. By comparing a Lifshitz background and the Light-Cone AdS, we show how an extra parameter can change the temperature scaling behavior of conductivity. Finally we discuss how OSM can be used to study other transport coefficients, such as diffusion constant, and effective temperature induced by the effective world volume horizon.Comment: 33 page

Self-bound dense objects in holographic QCD

We study a self-bound dense object in the hard wall model. We consider a spherically symmetric dense object which is characterized by its radial density distribution and non-uniform but spherically symmetric chiral condensate. For this we analytically solve the partial differential equations in the hard wall model and read off the radial coordinate dependence of the density and chiral condensate according to the AdS/CFT correspondence. We then attempt to describe nucleon density profiles of a few nuclei within our framework and observe that the confinement scale changes from a free nucleon to a nucleus. We briefly discuss how to include the effect of higher dimensional operator into our study. We finally comment on possible extensions of our work.Comment: 17 pages, 5 figures, figures replaced, minor revision, to appear in JHE

The Rich Structure of Gauss-Bonnet Holographic Superconductors

We study fully backreacting, Gauss-Bonnet (GB) holographic superconductors in 5 bulk spacetime dimensions. We explore the system's dependence on the scalar mass for both positive and negative GB coupling, $\alpha$. We find that when the mass approaches the Breitenlohner-Freedman (BF) bound and $\alpha\rightarrow L^2/4$ the effect of backreaction is to increase the critical temperature, $T_c$, of the system: the opposite of its effect in the rest of parameter space. We also find that reducing $\alpha$ below zero increases $T_c$ and that the effect of backreaction is diminished. We study the zero temperature limit, proving that this system does not permit regular solutions for a non-trivial, tachyonic scalar field and constrain possible solutions for fields with positive masses. We investigate singular, zero temperature solutions in the Einstein limit but find them to be incompatible with the concept of GB gravity being a perturbative expansion of Einstein gravity. We study the conductivity of the system, finding that the inclusion of backreaction hinders the development of poles in the conductivity that are associated with quasi-normal modes approaching the real axis from elsewhere in the complex plane.Comment: 26 pages, 11 figures, V3, Added discussion of non-tachyonic scalars, alterations to figures and tex

A Matrix Model for Baryons and Nuclear Forces

We propose a new matrix model describing multi-baryon systems. We derive the action from open string theory on the wrapped baryon vertex D-branes embedded in the D4-D8 model of large N holographic QCD. The positions of k baryons are unified into k x k matrices, with spin/isospin of the baryons encoded in a set of k-vectors. Holographic baryons are known to be very small in the large 't Hooft coupling limit, and our model offers a better systematic approach to dynamics of such baryons at short distances. We compute energetics and spectra (k=1), and also short-distance nuclear force (k=2). In particular, we obtain a new size of the holographic baryon and find a precise form of the repulsive core of nucleons. This matrix model complements the instanton soliton picture of holographic baryons, whose small size turned out to be well below the natural length scale of the approximation involved there. Our results show that, nevertheless, the basic properties of holographic baryons obtained there are robust under stringy corrections within a few percents.Comment: 30 pages. v3: more comments added, published versio

Symmetry energy of dense matter in holographic QCD

We study the nuclear symmetry energy of dense matter using holographic QCD. To this end, we consider two flavor branes with equal quark masses in a D4/D6/D6 model. We find that at all densities the symmetry energy monotonically increases. At small densities, it exhibits a power law behavior with the density, $E_{\rm sym} \sim \rho^{1/2}$.Comment: 9 pages, 3 figure

Predictive modeling of die filling of the pharmaceutical granules using the flexible neural tree

In this work, a computational intelligence (CI) technique named flexible neural tree (FNT) was developed to predict die filling performance of pharmaceutical granules and to identify significant die filling process variables. FNT resembles feedforward neural network, which creates a tree-like structure by using genetic programming. To improve accuracy, FNT parameters were optimized by using differential evolution algorithm. The performance of the FNT-based CI model was evaluated and compared with other CI techniques: multilayer perceptron, Gaussian process regression, and reduced error pruning tree. The accuracy of the CI model was evaluated experimentally using die filling as a case study. The die filling experiments were performed using a model shoe system and three different grades of microcrystalline cellulose (MCC) powders (MCC PH 101, MCC PH 102, and MCC DG). The feed powders were roll-compacted and milled into granules. The granules were then sieved into samples of various size classes. The mass of granules deposited into the die at different shoe speeds was measured. From these experiments, a dataset consisting true density, mean diameter (d50), granule size, and shoe speed as the inputs and the deposited mass as the output was generated. Cross-validation (CV) methods such as 10FCV and 5x2FCV were applied to develop and to validate the predictive models. It was found that the FNT-based CI model (for both CV methods) performed much better than other CI models. Additionally, it was observed that process variables such as the granule size and the shoe speed had a higher impact on the predictability than that of the powder property such as d50. Furthermore, validation of model prediction with experimental data showed that the die filling behavior of coarse granules could be better predicted than that of fine granules

Is lymphovascular invasion a powerful predictor for biochemical recurrence in pT3 N0 prostate cancer?: Results from the K-CaP database

To assess the impact of lymphovascular invasion (LVI) on the risk of biochemical recurrence (BCR) in pT3 N0 prostate cancer, clinical data were extracted from 1,622 patients with pT3 N0 prostate cancer from the K-CaP database. Patients with neoadjuvant androgen deprivation therapy (n = 325) or insufficient pathologic or follow-up data (n = 87) were excluded. The primary endpoint was the oncologic importance of LVI, and the secondary endpoint was the hierarchical relationships for estimating BCR between the evaluated variables. LVI was noted in 260 patients (21.5%) and was significantly associated with other adverse clinicopathologic features. In the multivariate Cox regression analysis, LVI was significantly associated with an increased risk of BCR after adjusting for known prognostic factors. In the Bayesian belief network analysis, LVI and pathologic Gleason score were found to be first-degree associates of BCR, whereas prostate-specific antigen (PSA) level, seminal vesicle invasion, perineural invasion, and high-grade prostatic intraepithelial neoplasia were considered second-degree associates. In the random survival forest, pathologic Gleason score, LVI, and PSA level were three most important variables in determining BCR of patients with pT3 N0 prostate cancer. In conclusion, LVI is one of the most powerful adverse prognostic factors for BCR in patients with pT3 N0 prostate cancer.1132Ysciescopu

Human vs robot baristas during the COVID-19 pandemic: effects of masks and vaccines on perceived safety and visit intention

Purpose This study aims to compare the effect of barista type (human vs robot) on perceived safety and examine the role of two moderators (mask-wearing and coronavirus vaccination) on the effects of barista type on perceived safety and visit intention. Design/methodology/approach The research design consists of three studies. Three experiments were sequentially designed and conducted to address research questions. Findings Study 1 found that perceived safety mediates the effect of barista type on customers’ visit intention. Study 2 revealed that the mask-wearing of human and robot baristas differently influences perceived safety. Study 3 showed that customers, especially where robot baristas are used, perceive the effect of mask-wearing differently depending on their coronavirus vaccination status. Research limitations/implications Given that the levels of restrictions vary worldwide, together with the extent of countries’ vaccination rollouts, caution is required when generalising the research findings. Practical implications The findings have practical implications for the hospitality industry, where the roles of face masks and coronavirus vaccines in shaping consumer psychology and behaviour have been underexplored. Originality/value Coronavirus vaccination is considered one of the most important driving forces for the recovery of hospitality businesses. As a heuristic-systematic model postulated, this study identified that vaccination status (fully vaccinated vs not vaccinated) changes the level of involvement when customers assess the level of risk in service environments. By pinpointing the function of service robots in safeguarding customers from the potential spread of the disease, this study broadens the scope of human–robot interaction research in hospitality

Multiple infarcted regenerative nodules in liver cirrhosis after decompensation of cirrhosis: a case series

These patients showed focal liver lesions, to be considered in the differential diagnosis of cirrhotic livers. Infarcted regenerative nodules may be underdiagnosed in patients with decompensation of cirrhosis. In order to differentiate these lesions from malignant tumors, serial imaging seems to be helpful. However, the main differential diagnosis should be an abscess. It is important to know the wide spectrum of image appearances of these lesions. Hypotension can lead to a reduction of portal and arterial liver flow. Since variceal bleeding or septic shock can induce hypotension - as observed in our patients - we conclude that this leads to infarction of such nodules

Chiral phase transitions and quantum critical points of the D3/D7(D5) system with mutually perpendicular E and B fields at finite temperature and density

We study chiral symmetry restoration with increasing temperature and density in gauge theories subject to mutually perpendicular electric and magnetic fields using holography. We determine the chiral symmetry breaking phase structure of the D3/D7 and D3/D5 systems in the temperature-density-electric field directions. A magnetic field may break the chiral symmetry and an additional electric field induces Ohm and Hall currents as well as restoring the chiral symmetry. At zero temperature the D3/D5 system displays a line of holographic BKT phase transitions in the density-electric field plane, while the D3/D7 system shows a mean-field phase transition. At intermediate temperatures, the transitions in the density-electric field plane are of first order at low density, transforming to second order at critical points as density rises. At high temperature the transition is only ever first order.Comment: 15 pages, 7 figures, v2: Added a referenc