6,219 research outputs found
Violating conformal invariance: Two-dimensional clusters grafted to wedges, cones, and branch points of Riemann surfaces
We present simulations of 2-d site animals on square and triangular lattices
in non-trivial geomeLattice animals are one of the few critical models in
statistical mechanics violating conformal invariance. We present here
simulations of 2-d site animals on square and triangular lattices in
non-trivial geometries. The simulations are done with the newly developed PERM
algorithm which gives very precise estimates of the partition sum, yielding
precise values for the entropic exponent (). In particular, we studied animals grafted to the tips of wedges
with a wide range of angles , to the tips of cones (wedges with the
sides glued together), and to branching points of Riemann surfaces. The latter
can either have sheets and no boundary, generalizing in this way cones to
angles degrees, or can have boundaries, generalizing wedges. We
find conformal invariance behavior, , only for small
angles (), while for
. These scalings hold both for wedges and cones. A heuristic
(non-conformal) argument for the behavior at large is given, and
comparison is made with critical percolation.Comment: 4 pages, includes 3 figure
Unraveling the Infrared Transient VVV-WIT-06: The Case for the Origin as a Classical Nova
Indexación: Scopus.E.Y.H. acknowledges the support provided by the National Science Foundation under Grant No. AST-1613472 and by the Florida Space Grant Consortium. L.G. acknowledges support from the FINCA visitor programme. The research work at the Physical Research Laboratory is funded by the Department of Space, Government of India. Facility: Magellan: Baade(FIRE).The enigmatic near-infrared transient VVV-WIT-06 underwent a large-amplitude eruption of unclear origin in 2013 July. Based on its light curve properties and late-time post-outburst spectra, various possibilities have been proposed in the literature for the origin of the object, namely a Type I supernova, a classical nova (CN), or a violent stellar merger event. We show that, of these possibilities, an origin in a CN outburst convincingly explains the observed properties of VVV-WIT-06. We estimate that the absolute K-band magnitude of the nova at maximum was M k = -8.2 ±0.5, its distance d = 13.35 ±2.18 kpc, and the extinction A v = 15.0 ±0.55 mag. © 2018. The American Astronomical Society. All rights reserved.https://iopscience.iop.org/article/10.3847/1538-4357/aae5d
Chromogranin A in uremia: Progressive retention of immunoreactive fragments
Chromogranin A in uremia: Progressive retention of immunoreactive fragments. Chromogranin A is a soluble protein that is stored and released with catecholamines from their secretory vesicles. Its measurement is a probe of exocytotic sympathoadrenal activity, and in plasma it may also be a useful tool in the diagnosis of peptide producing endocrine neoplasms. Because we have found that chromogranin A is elevated in secondary (uremic) hyperparathyroidism, we systematically investigated the influence of renal dysfunction and its attendant hyperparathyroidism on chromogranin A in several subject groups: normal controls (serum creatinine≤1.2 mg/dl), nonazotemic renal transplant recipients, nonazotemic subjects with glomerular disease (serum creatinine between 1.2 and 2 mg/dl), mid-range renal disease subjects (serum creatinine between 2 and 7.5 mg/dl), and end-stage renal disease subjects (serum creatinine <7.5 mg/dl). Plasma chromogranin A rose with deterioration of renal function, and the rise was independent of etiologic diagnosis, blood pressure, or indices of sympathoadrenal activity or hyperparathyroidism. Size fractionation of uremic plasma by gel filtration, and immunoextraction by region-specific anti-chromo-granin A (anti-N-terminal, anti-C-terminal, and antimid-molecule) antibodies suggested that chromogranin A immunoreactivity circulates in uremia as lower molecular weight fragments of the parent chromogranin A molecule, with mid-molecule fragments the major constituent. This immunoreactivity is only minimally removed by peritoneal dialysis and is not at all hemodialyzable. The uremia-dose-dependent accumulation of chromogranin A immunoreactive fragments in renal failure suggests that the kidney is a major site of disposition or removal of the immunoreactivity. Furthermore, lack of detectable chromogranin A immunoreactivity in normal subjects' urine suggests that the immunoreactivity is destroyed as it is removed by the kidney. We conclude that plasma chromogranin A increases in proportion to degree of renal insufficiency and that renal function must therefore be controlled when using plasma chromogranin A in the investigation of amine or peptide hormone storage and release
Kaon photoproduction: background contributions, form factors and missing resonances
The photoproduction p(gamma, K+)Lambda process is studied within a
field-theoretic approach. It is shown that the background contributions
constitute an important part of the reaction dynamics. We compare predictions
obtained with three plausible techniques for dealing with these background
contributions. It appears that the extracted resonance parameters drastically
depend on the applied technique. We investigate the implications of the
corrections to the functional form of the hadronic form factor in the contact
term, recently suggested by Davidson and Workman (Phys. Rev. C 63, 025210). The
role of background contributions and hadronic form factors for the
identification of the quantum numbers of ``missing'' resonances is discussed.Comment: 11 pages, 7 eps figures, submitted to Phys. Rev.
Experimental Studies of Low-field Landau Quantization in Two-dimensional Electron Systems in GaAs/AlGaAs Heterostructures
By applying a magnetic field perpendicular to GaAs/AlGaAs two-dimensional
electron systems, we study the low-field Landau quantization when the thermal
damping is reduced with decreasing the temperature. Magneto-oscillations
following Shubnikov-de Haas (SdH) formula are observed even when their
amplitudes are so large that the deviation to such a formula is expected. Our
experimental results show the importance of the positive magneto-resistance to
the extension of SdH formula under the damping induced by the disorder.Comment: 9 pages, 3 figure
Quantum-Logic Gate between Two Optical Photons with an Average Efficiency above 40%
Optical qubits uniquely combine information transfer in optical fibers with a
good processing capability and are therefore attractive tools for quantum
technologies. A large challenge, however, is to overcome the low efficiency of
two-qubit logic gates. The experimentally achieved efficiency in an optical
controlled NOT (CNOT) gate reached approximately 11% in 2003 and has seen no
increase since. Here we report on a new platform that was designed to surpass
this long-standing record. The new scheme avoids inherently probabilistic
protocols and, instead, combines aspects of two established quantum nonlinear
systems: atom-cavity systems and Rydberg electromagnetically induced
transparency. We demonstrate a CNOT gate between two optical photons with an
average efficiency of 41.7(5)% at a postselected process fidelity of 81(2)%.
Moreover, we extend the scheme to a CNOT gate with multiple target qubits and
produce entangled states of presently up to five photons. All these
achievements are promising and have the potential to advance optical quantum
information processing in which almost all advanced protocols would profit from
high-efficiency logic gates.Comment: In this revision, we extend the discussion of the efficiency in Sec.
IV.C and we add models in appendices B, E, and L-
Szeg\"o kernel asymptotics and Morse inequalities on CR manifolds
We consider an abstract compact orientable Cauchy-Riemann manifold endowed
with a Cauchy-Riemann complex line bundle. We assume that the manifold
satisfies condition Y(q) everywhere. In this paper we obtain a scaling
upper-bound for the Szeg\"o kernel on (0, q)-forms with values in the high
tensor powers of the line bundle. This gives after integration weak Morse
inequalities, analogues of the holomorphic Morse inequalities of Demailly. By a
refined spectral analysis we obtain also strong Morse inequalities which we
apply to the embedding of some convex-concave manifolds.Comment: 40 pages, the constants in Theorems 1.1-1.8 have been modified by a
multiplicative constant 1/2 ; v.2 is a final updat
Is mindfulness Buddhist? (and why it matters).
Modern exponents of mindfulness meditation promote the therapeutic effects of "bare attention"--a sort of non-judgmental, non-discursive attending to the moment-to-moment flow of consciousness. This approach to Buddhist meditation can be traced to Burmese Buddhist reform movements of the first half of the 20th century, and is arguably at odds with more traditional Theravāda Buddhist doctrine and meditative practices. But the cultivation of present-centered awareness is not without precedent in Buddhist history; similar innovations arose in medieval Chinese Zen (Chan) and Tibetan Dzogchen. These movements have several things in common. In each case the reforms were, in part, attempts to render Buddhist practice and insight accessible to laypersons unfamiliar with Buddhist philosophy and/or unwilling to adopt a renunciatory lifestyle. In addition, these movements all promised astonishingly quick results. And finally, the innovations in practice were met with suspicion and criticism from traditional Buddhist quarters. Those interested in the therapeutic effects of mindfulness and bare attention are often not aware of the existence, much less the content, of the controversies surrounding these practices in Asian Buddhist history
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