Chiral Condensate in Holographic QCD with Baryon Density

We consider the chiral condensate in the baryonic dense medium using the generalized Sakai-Sugimoto model. It is defined as the vacuum expectation value of open Wilson line that is proposed to be calculated by use of the area of world-sheet instanton. We evaluate it in confined as well as deconfined phase. In both phases, the chiral condensate has a minimum as a function of baryon density. In the deconfined phase, taking into account the chiral symmetry restoration, we classify the behavior of chiral condensate into three types. One can set the parameter of the theory such that the results, in low but sufficiently higher density, is in agreement with the expectation from QCD.Comment: 23 pages, 8 figure

Magnetized Domain Walls in the Deconfined Sakai-Sugimoto Model at Finite Baryon Density

The magnetized pure pion gradient ($\mathcal{5}\phi$) phase in the deconfined Sakai-Sugimoto model is explored at zero and finite temperature. We found that the temperature has very small effects on the phase. The thermodynamical properties of the phase shows that the excitations behave like a scalar solitonic free particles. By comparing the free energy of the pion gradient phase to the competing multiquark-pion gradient (MQ-$\mathcal{5}\phi$) phase, it becomes apparent that the pure pion gradient is less thermodynamically preferred than the MQ-$\mathcal{5}\phi$ phase. However, in the parameter space where the baryonic chemical potential is smaller than the onset value of the multiquark, the dominating magnetized nuclear matter is the pion gradient phase.Comment: 20 pages, 9 figure

Acute liver failure following hemodialysis arteriovenous graft placement: a case report

<p>Abstract</p> <p>Introduction</p> <p>Severe high-output cardiac failure is a serious complication of high-flow vascular access requiring immediate intervention. Ischemic hepatitis is defined as a massive increase in serum transaminase levels due to an imbalance between hepatic oxygen supply and demand in the absence of other acute causes of liver damage. It is typically preceded by hypotension, hypoxemia, or both, and occurs mostly in elderly patients with right-sided congestive heart failure.</p> <p>Case presentation</p> <p>We report a fatal case of acute liver failure in an 84-year-old Caucasian man with high-output cardiac failure due to arteriovenous hemodialysis access. The chronological sequence of acute liver failure in the context of vascular access created two days before suggests that ischemic hepatitis was the result of high-output cardiac failure due to vascular access.</p> <p>Conclusions</p> <p>A thorough cardiac assessment should be performed in patients with severe cardiac disease prior to placing an arteriovenous access, and arteriovenous fistula should be the preferred vascular access.</p

The Spectrum of Strings on Warped AdS_3 x S^3

String theory on NS-NS AdS_3 x S^3 admits an exactly marginal deformation which breaks the SL(2,R)_R x SL(2,R)_L isometry of AdS_3 down to SL(2,R)_R x U(1)_L. The holographic dual is an exotic and only partially understood type of two-dimensional CFT with a reduced unbroken global conformal symmetry group. In this paper we study the deformed theory on the string worldsheet. It is found to be related by a spectral flow which is nonlocal in spacetime to the undeformed worldsheet theory. An exact formula for the spectrum of massive strings is presented.Comment: 26 pages, no figure

Flavor-symmetry Breaking with Charged Probes

We discuss the recombination of brane/anti-brane pairs carrying $D3$ brane charge in $AdS_5 \times S^5$. These configurations are dual to co-dimension one defects in the ${\cal N}=4$ super-Yang-Mills description. Due to their $D3$ charge, these defects are actually domain walls in the dual gauge theory, interpolating between vacua of different gauge symmetry. A pair of unjoined defects each carry localized $(2+1)$ dimensional fermions and possess a global $U(N)\times U(N)$ flavor symmetry while the recombined brane/anti-brane pairs exhibit only a diagonal U(N). We study the thermodynamics of this flavor-symmetry breaking under the influence of external magnetic field.Comment: 21 pages, 10 figure

Scaling up kangaroo mother care in South Africa: 'on-site' versus 'off-site' educational facilitation

Background Scaling up the implementation of new health care interventions can be challenging and demand intensive training or retraining of health workers. This paper reports on the results of testing the effectiveness of two different kinds of face-to-face facilitation used in conjunction with a well-designed educational package in the scaling up of kangaroo mother care. Methods : Thirty-six hospitals in the Provinces of Gauteng and Mpumalanga in South Africa were targeted to implement kangaroo mother care and participated in the trial. The hospitals were paired with respect to their geographical location and annual number of births. One hospital in each pair was randomly allocated to receive either 'on-site' facilitation (Group A) or 'off-site' facilitation (Group B). Hospitals in Group A received two on-site visits, whereas delegates from hospitals in Group B attended one off-site, 'hands-on' workshop at a training hospital. All hospitals were evaluated during a site visit six to eight months after attending an introductory workshop and were scored by means of an existing progress-monitoring tool with a scoring scale of 0-30. Successful implementation was regarded as demonstrating evidence of practice (score >10) during the site visit. Results : There was no significant difference between the scores of Groups A and B (p = 0.633). Fifteen hospitals in Group A and 16 in Group B demonstrated evidence of practice. The median score for Group A was 16.52 (range 00.00-23.79) and that for Group B 14.76 (range 07.50-23.29). Conclusion : A previous trial illustrated that the implementation of a new health care intervention could be scaled up by using a carefully designed educational package, combined with face-to-face facilitation by respected resource persons. This study demonstrated that the site of facilitation, either on site or at a centre of excellence, did not influence the ability of a hospital to implement KMC. The choice of outreach strategy should be guided by local circumstances, cost and the availability of skilled facilitators

Magnetic properties of holographic multiquarks in the quark-gluon plasma

We study the magnetic properties of the coloured multiquark states in the quark-gluon plasma where the gluons are deconfined and the chiral symmetry is still broken, using the Sakai-Sugimoto model. There are two possible magnetized multiquark configurations. Both configurations converge to the same configuration at the critical field and temperature before they dissociate altogether either into less coloured multiquarks or into other phases for a fixed density. It is also found that the multiquarks with higher colour charges respond more to the external magnetic field in both the magnetization and the degree of chiral symmetry breaking. Magnetic field also makes it more difficult for multiquark states with large colour charges to satisfy the equilibrium condition of the configuration in the gravity dual picture. As long as the chemical potential $\mu > \mu_{onset}$, the magnetized multiquarks phase is thermodynamically preferred over the magnetized vacuum. Pure pion gradient and the chiral-symmetric quark-gluon plasma ($\chi_S$-QGP) phase for the general Sakai-Sugimoto model are discussed and compared with the multiquark phase in the presence of the magnetic field. It is found that at large densities and moderate fields, the mixed phase of multiquarks and the pion gradient is thermodynamically preferred over the $\chi_S$-QGP.Comment: 26 pages, 16 figures, revised version with significant changes and extension to other magnetized nuclear phase

Static Charges in the Low-Energy Theory of the S-Duality Twist

We continue the study of the low-energy limit of N=4 super Yang-Mills theory compactified on a circle with S-duality and R-symmetry twists that preserve N=6 supersymmetry in 2+1D. We introduce external static supersymmetric quark and anti-quark sources into the theory and calculate the Witten Index of the resulting Hilbert space of ground states on a torus. Using these results we compute the action of simple Wilson loops on the Hilbert space of ground states without sources. In some cases we find disagreement between our results for the Wilson loop eigenvalues and previous conjectures about a connection with Chern-Simons theory.Comment: 73 pages, two paragraphs added, one to the introduction and one to the discussio

Thermodynamic Properties of Holographic Multiquark and the Multiquark Star

We study thermodynamic properties of the multiquark nuclear matter. The dependence of the equation of state on the colour charges is explored both analytically and numerically in the limits where the baryon density is small and large at fixed temperature between the gluon deconfinement and chiral symmetry restoration. The gravitational stability of the hypothetical multiquark stars are discussed using the Tolman-Oppenheimer-Volkoff equation. Since the equations of state of the multiquarks can be well approximated by different power laws for small and large density, the content of the multiquark stars has the core and crust structure. We found that most of the mass of the star comes from the crust region where the density is relatively small. The mass limit of the multiquark star is determined as well as its relation to the star radius. For typical energy density scale of $10\text{GeV}/\text{fm}^{3}$, the converging mass and radius of the hypothetical multiquark star in the limit of large central density are approximately $2.6-3.9$ solar mass and 15-27 km. The adiabatic index and sound speed distributions of the multiquark matter in the star are also calculated and discussed. The sound speed never exceeds the speed of light and the multiquark matters are thus compressible even at high density and pressure.Comment: 27 pages, 17 figures, 1 table, JHEP versio

Order by disorder and spiral spin liquid in frustrated diamond lattice antiferromagnets

Frustration refers to competition between different interactions that cannot be simultaneously satisfied, a familiar feature in many magnetic solids. Strong frustration results in highly degenerate ground states, and a large suppression of ordering by fluctuations. Key challenges in frustrated magnetism are characterizing the fluctuating spin-liquid regime and determining the mechanism of eventual order at lower temperature. Here, we study a model of a diamond lattice antiferromagnet appropriate for numerous spinel materials. With sufficiently strong frustration a massive ground state degeneracy develops amongst spirals whose propagation wavevectors reside on a continuous two-dimensional ``spiral surface'' in momentum space. We argue that an important ordering mechanism is entropic splitting of the degenerate ground states, an elusive phenomena called order-by-disorder. A broad ``spiral spin-liquid'' regime emerges at higher temperatures, where the underlying spiral surface can be directly revealed via spin correlations. We discuss the agreement between these predictions and the well characterized spinel MnSc2S4