The Case of the Missing Gates: Complexity of Jackiw-Teitelboim Gravity

The Jackiw-Teitelboim (JT) model arises from the dimensional reduction of charged black holes. Motivated by the holographic complexity conjecture, we calculate the late-time rate of change of action of a Wheeler-DeWitt patch in the JT theory. Surprisingly, the rate vanishes. This is puzzling because it contradicts both holographic expectations for the rate of complexification and also action calculations for charged black holes. We trace the discrepancy to an improper treatment of boundary terms when naively doing the dimensional reduction. Once the boundary term is corrected, we find exact agreement with expectations. We comment on the general lessons that this might hold for holographic complexity and beyond.Comment: 31 pages, 5 figure

Search for nearby stars among proper motion stars selected by optical-to-infrared photometry. I. Discovery of LHS 2090 at spectroscopic distance of d=6pc

We present the discovery of a previously unknown very nearby star - LHS 2090 at a distance of only d=6 pc. In order to find nearby (i.e. d < 25 pc) red dwarfs, we re-identified high proper motion stars ($\mu >$ 0.18 arcsec/yr) from the NLTT catalogue (Luyten \cite{luyten7980}) in optical Digitized Sky Survey data for two different epochs and in the 2MASS data base. Only proper motion stars with large $R-K_s$ colour index and with relatively bright infrared magnitudes ($K_s<10$) were selected for follow-up spectroscopy. The low-resolution spectrum of LHS 2090 and its large proper motion (0.79 arcsec/yr) classify this star as an M6.5 dwarf. The resulting spectroscopic distance estimate from comparing the infrared $JHK_s$ magnitudes of LHS 2090 with absolute magnitudes of M6.5 dwarfs is $6.0\pm1.1$ pc assuming an uncertainty in absolute magnitude of $\pm$0.4 mag.Comment: 3 pages, 1 figure, accepted for publication in Astronomy and Astrophysics Letter

CORRELATION BETWEEN IMPAIRMENT AND MOTOR PERFORMANCE DURING REACHING TASKS IN SUBJECTS WITH SPASTIC HEMIPARESIS

Objective: The main purposes of this study were to examine, in subjects with chronic hemiparesis following a stroke: (i) the correlations between tests of muscle tone, stiffness, spasticity, paresis and co-contraction, and (ii) the correlations of these tests and measurements of impairment to upper extremity motor performance. Design: Prospective, cross-sectional, correlation matrix using sample of convenience. Subjects: Thirteen subjects with chronic hemiparesis secondary to a cerebrovascular accident (stroke) were tested. Methods: Subjects were assessed using the Fugl-Meyer Upper Extremity Motor Assessment, modified Ashworth scale, deep tendon reflexes, and muscle characteristics that included quantification of muscle stiffness, paresis and co-contraction during a voluntary reaching task and during passive movements. Surface electromyographic and myotonometric muscle stiffness data were obtained during movement trials. Results: Biceps and triceps brachii muscle paresis and excess biceps brachii co-contraction during voluntary reaching had the highest correlations to decreased motor performance. Muscle tone measurements did not have significant correlations to upper extremity performance. Conclusion: Paresis of elbow flexors and extensors and excess co-contraction of the biceps brachii during voluntary reaching appear to be most predictive of upper extremity motor performance. Results are discussed in relation to the specific challenges these findings pose for spastic paresis clinical management

Quantum Gravity in the Lab: Teleportation by Size and Traversable Wormholes, Part II

In [1] we discussed how quantum gravity may be simulated using quantum devices and gave a specific proposal -- teleportation by size and the phenomenon of size-winding. Here we elaborate on what it means to do 'Quantum Gravity in the Lab' and how size-winding connects to bulk gravitational physics and traversable wormholes. Perfect size-winding is a remarkable, fine-grained property of the size wavefunction of an operator; we show from a bulk calculation that this property must hold for quantum systems with a nearly-AdS_2 bulk. We then examine in detail teleportation by size in three systems: the Sachdev-Ye-Kitaev model, random matrices, and spin chains, and discuss prospects for realizing these phenomena in near-term quantum devices.Comment: 50 pages, 14 figures, Part II of arXiv:1911.0631

Quantum Gravity in the Lab: Teleportation by Size and Traversable Wormholes

With the long-term goal of studying models of quantum gravity in the lab, we propose holographic teleportation protocols that can be readily executed in table-top experiments. These protocols exhibit similar behavior to that seen in the recent traversable wormhole constructions of [1,2]: information that is scrambled into one half of an entangled system will, following a weak coupling between the two halves, unscramble into the other half. We introduce the concept of teleportation by size to capture how the physics of operator-size growth naturally leads to information transmission. The transmission of a signal through a semi-classical holographic wormhole corresponds to a rather special property of the operator-size distribution we call size winding. For more general systems (which may not have a clean emergent geometry), we argue that imperfect size winding is a generalization of the traversable wormhole phenomenon. In addition, a form of signalling continues to function at high temperature and at large times for generic chaotic systems, even though it does not correspond to a signal going through a geometrical wormhole, but rather to an interference effect involving macroscopically different emergent geometries. Finally, we outline implementations feasible with current technology in two experimental platforms: Rydberg atom arrays and trapped ions.Comment: 33 pages, 5 figures. This paper has a companion paper (Part II) by the same author

Lipidomics Reveals Early Metabolic Changes in Subjects with Schizophrenia: Effects of Atypical Antipsychotics

There is a critical need for mapping early metabolic changes in schizophrenia to capture failures in regulation of biochemical pathways and networks. This information could provide valuable insights about disease mechanisms, trajectory of disease progression, and diagnostic biomarkers. We used a lipidomics platform to measure individual lipid species in 20 drug-naïve patients with a first episode of schizophrenia (FE group), 20 patients with chronic schizophrenia that had not adhered to prescribed medications (RE group), and 29 race-matched control subjects without schizophrenia. Lipid metabolic profiles were evaluated and compared between study groups and within groups before and after treatment with atypical antipsychotics, risperidone and aripiprazole. Finally, we mapped lipid profiles to n3 and n6 fatty acid synthesis pathways to elucidate which enzymes might be affected by disease and treatment. Compared to controls, the FE group showed significant down-regulation of several n3 polyunsaturated fatty acids (PUFAs), including 20:5n3, 22:5n3, and 22:6n3 within the phosphatidylcholine and phosphatidylethanolamine lipid classes. Differences between FE and controls were only observed in the n3 class PUFAs; no differences where noted in n6 class PUFAs. The RE group was not significantly different from controls, although some compositional differences within PUFAs were noted. Drug treatment was able to correct the aberrant PUFA levels noted in FE patients, but changes in re patients were not corrective. Treatment caused increases in both n3 and n6 class lipids. These results supported the hypothesis that phospholipid n3 fatty acid deficits are present early in the course of schizophrenia and tend not to persist throughout its course. These changes in lipid metabolism could indicate a metabolic vulnerability in patients with schizophrenia that occurs early in development of the disease. © 2013 McEvoy et al

Intranasal administration of acetylcholinesterase inhibitors

This short review outlines the rationale, challenges, and opportunities for intranasal acetylcholinesterases, in particular galantamine. An in vitro screening model facilitated the development of a therapeutically viable formulation. In vivo testing confirmed achievement of therapeutically relevant drug levels that matched or exceeded those for oral dosing, with a dramatic reduction in undesired emetic responses. Intranasal drug delivery is an effective option for the treatment of Alzheimer's disease and other central nervous system disorders

The High Angular Resolution Multiplicity of Massive Stars

We present the results of a speckle interferometric survey of Galactic massive stars that complements and expands upon a similar survey made over a decade ago. The speckle observations were made with the KPNO and CTIO 4 m telescopes and USNO speckle camera, and they are sensitive to the detection of binaries in the angular separation regime between 0.03" and 5" with relatively bright companions (Delta V < 3). We report on the discovery of companions to 14 OB stars. In total we resolved companions of 41 of 385 O-stars (11%), 4 of 37 Wolf-Rayet stars (11%), and 89 of 139 B-stars (64%; an enriched visual binary sample that we selected for future orbital determinations). We made a statistical analysis of the binary frequency among the subsample that are listed in the Galactic O Star Catalog by compiling published data on other visual companions detected through adaptive optics studies and/or noted in the Washington Double Star Catalog and by collecting published information on radial velocities and spectroscopic binaries. We find that the binary frequency is much higher among O-stars in clusters and associations compared to the numbers for field and runaway O-stars, consistent with predictions for the ejection processes for runaway stars. We present a first orbit for the O-star Delta Orionis, a linear solution of the close, apparently optical, companion of the O-star Iota Orionis, and an improved orbit of the Be star Delta Scorpii. Finally, we list astrometric data for another 249 resolved and 221 unresolved targets that are lower mass stars that we observed for various other science programs.Comment: 76 pages, 6 figures, 11 table

Axillary sentinel lymph node biopsy after mastectomy: a case report

<p>Abstract</p> <p>Background</p> <p>Sentinel lymph node biopsy has been established as the preferred method for staging early breast cancer. A prior history of mastectomy is felt to be a contraindication.</p> <p>Case presentation</p> <p>A patient with recurrent breast cancer in her skin flap was discovered to have positive axillary sentinel nodes by sentinel lymph node biopsy five years after mastectomy for ductal carcinoma in situ.</p> <p>Conclusion</p> <p>A prior history of mastectomy may not be an absolute contraindication to sentinel lymph node biopsy.</p