Matrix dynamics of fuzzy spheres

We study the dynamics of fuzzy two-spheres in a matrix model which represents string theory in the presence of RR flux. We analyze the stability of known static solutions of such a theory which contain commuting matrices and SU(2) representations. We find that irreducible as well as reducible representations are stable. Since the latter are of higher energy, this stability poses a puzzle. We resolve this puzzle by noting that reducible representations have marginal directions corresponding to non-spherical deformations. We obtain new static solutions by turning on these marginal deformations. These solutions now have instability or tachyonic directions. We discuss condensation of these tachyons which correspond to classical trajectories interpolating from multiple, small fuzzy spheres to a single, large sphere. We briefly discuss spatially independent configurations of a D3/D5 system described by the same matrix model which now possesses a supergravity dual.Comment: 26 pages, 3 figures, uses JHEP.cls; (v2) references adde

Active sound radiation control with secondary sources at the edge of the opening

© 2016 Elsevier Ltd Planar virtual sound barriers with secondary sources over the entire opening have been demonstrated an effective way to achieve global control of sound transmission through the opening, but loudspeakers in the middle of the opening affect ventilation, lighting and normal access through it. To avoid the problem, this technical note proposes to implement secondary sources at the edge of a cavity opening and investigates the active sound reduction performance of the system numerically and experimentally. Unlike secondary sources over the entire opening which can achieve sound reduction at any frequency as long as there are sufficient of them, there exists an upper bound of effective frequency for global control when secondary sources are at the edge of the opening; however, local control is always achievable. Preliminary experiments were conducted on an open wooden box and a semi-closed meeting room to support the conclusions

Efektywność leczenia zespołu bólowego miednicy mniejszej metodą neurektomii przedkrzyżowej u pacjentek z i bez endometriozy

Abstract Objective: Presacral neurectomy (PSN) is used in treatment of central chronic pelvic pain (CPP); however, the confounding effect of concomitant resection of endometriosis remains uncertain. This study was undertaken to evaluate and compare the effectiveness of presacral neurectomy (PSN) in the presence and absence of endometriosis. Material and Methods: Twenty-three women with midline CPP (age 30.3+/-7.9, range 21-46) unresponsive to medical therapy were recruited to the study. Endometriosis was absent in seven and present in sixteen subjects. Laparoscopic PSN using a harmonic scalpel was performed in all subjects; simultaneous excision of endometriotic lesions was also carried out in subjects with endometriosis. Intensity of dysmenorrhoea and pelvic pain was measured by visual analogue pain scale (VAPS) at 3 and 12 months postoperatively. Results: Dysmenorrhoea decreased at 3 months by 75% (P=0.018) in those without endometriosis and by 78% (P=0.001) in those with endometriosis. At 12-months, dysmenorrhea increased in women with endometriosis (P=0.008), but not in those without endometriosis. Pelvic pain not related to menses decreased by 67% (P=0.0007) and by 87% (P=0.028), respectively, in women with and without endometriosis. Dyspareunia, declined dramatically at 3 and 12 months to a median score of 0 (the majority of subjects had no discomfort; PStreszczenie Cel pracy: Neurektomia przedkrzyżowa jest stosowana w leczeniu zespołu bólowego miednicy mniejszej, jakkolwiek sumaryczny efekt jednoczasowo przeprowadzonej resekcji ognisk endometriozy pozostaje niejasny. Prezentowana praca ma na celu porównanie skuteczności laparoskopowej neurektomii przedkrzyżowej w przypadku obecności endometriozy, oraz u chorych, u których ta choroba nie występuje. Materiał i metody: Badaniem objęto dwadzieścia trzy kobiety z centralnie zlokalizowanym przewlekłym bólem miednicy mniejszej (wiek 30,3+/-7,9; 21-46 lat), nieodpowiadającym na leczenie farmakologiczne. Endometriozę stwierdzono u 16 pacjentek. W badanej grupie wykonano laparoskopową neurektomię przedkrzyżową z zastosowaniem skalpela harmonicznego, uzupełnioną o wycięcie ognisk endometriozy w 16 w/w przypadkach. Nasilenie bólu towarzyszącego krwawieniu miesiączkowemu oraz bólu niezwiązanego z krwawieniem oceniano na podstawie wzrokowej skali bólu (VAPS) przed zabiegiem oraz po 3 i 12 miesiącach po operacji. Bolesność stosunków płciowych oceniono z zastosowaniem czterostopniowej skali. Wyniki: Po 3 miesiącach od operacji intensywność bólu związanego z krwawieniem miesiączkowym zmniejszyła się znacząco w obu grupach pacjentek (u chorych bez endometriozy o 75% (P=0,018), a w grupie z endometriozą o 78% (P=0,001). Po 12 miesiącach zaobserwowano wzrost intensywności odczuwanego bólu u kobiet z endometriozą (P=0,008), natomiast u pacjentek bez endometriozy poprawa była na niezmienionym poziomie. Odczuwalność bólu w miednicy mniejszej niezwiązanego z krwawieniem miesiączkowym zmniejszyła się na skutek operacji o 67% (P=0,0007) i o 87% (P=0,028) odpowiednio w grupie z endometriozą i bez endometriozy. Bolesność stosunków płciowych zmniejszyła się istotnie 3 miesiące po operacji i efekt utrzymywał się nadal po 12 miesiącach (większość pacjentek nie podawała żadnego dyskomfortu,

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 ${\mathcal{N}}=1$ 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

Transport properties of N=4 supersymmetric Yang-Mills theory at finite coupling

Gauge theory-string theory duality describes strongly coupled N=4 supersymmetric SU(n) Yang-Mills theory at finite temperature in terms of near extremal black 3-brane geometry in type IIB string theory. We use this correspondence to compute the leading correction in inverse 't Hooft coupling to the shear diffusion constant, bulk viscosity and the speed of sound in the large-n N=4 supersymmetric Yang-Mills theory plasma. The transport coefficients are extracted from the dispersion relation for the shear and the sound wave lowest quasinormal modes in the leading order alpha'-corrected black D3 brane geometry. We find the shear viscosity extracted from the shear diffusion constant to agree with result of [hep-th/0406264]; also, the leading correction to bulk viscosity and the speed of sound vanishes. Our computation provides a highly nontrivial consistency check on the hydrodynamic description of the alpha'-corrected nonextremal black branes in string theory.Comment: 19 pages, LaTe

Folds in 2D String Theories

We study maps from a 2D world-sheet to a 2D target space which include folds. The geometry of folds is discussed and a metric on the space of folded maps is written down. We show that the latter is not invariant under area preserving diffeomorphisms of the target space. The contribution to the partition function of maps associated with a given fold configuration is computed. We derive a description of folds in terms of Feynman diagrams. A scheme to sum up the contributions of folds to the partition function in a special case is suggested and is shown to be related to the Baxter-Wu lattice model. An interpretation of folds as trajectories of particles in the adjoint representation of $SU(N)$ gauge group in the large $N$ limit which interact in an unusual way with the gauge fields is discussed.Comment: 56 pages, latex, followed by epsf, 13 uuencoded epsf figure