954 research outputs found
Exploiting the photonic nonlinearity of free-space subwavelength arrays of atoms
Ordered ensembles of atoms, such as atomic arrays, exhibit distinctive
features from their disordered counterpart. In particular, while collective
modes in disordered ensembles show a linear optical response, collective
subradiant excitations of subwavelength arrays are endowed with an intrinsic
non-linearity. Such non-linearity has both a coherent and a dissipative
component: two excitations propagating in the array scatter off each other
leading to formation of correlations and to emission into free space modes. We
show how to take advantage of such non-linearity to coherently prepare a single
excitation in a subradiant (dark) collective state of a one dimensional array
as well as to perform an entangling operation on dark states of parallel
arrays. We discuss the main source of errors represented by disorder introduced
by atomic center-of-mass fluctuations, and we propose a practical way to
mitigate its effects.Comment: Published version. Minor typos corrected. 12+13 pages, 7+6 figure
Developmental Topographical Disorientation With Concurrent Face Recognition Deficit: A Case Report
Reducing the impact of radioactivity on quantum circuits in a deep-underground facility
As quantum coherence times of superconducting circuits have increased from
nanoseconds to hundreds of microseconds, they are currently one of the leading
platforms for quantum information processing. However, coherence needs to
further improve by orders of magnitude to reduce the prohibitive hardware
overhead of current error correction schemes. Reaching this goal hinges on
reducing the density of broken Cooper pairs, so-called quasiparticles. Here, we
show that environmental radioactivity is a significant source of nonequilibrium
quasiparticles. Moreover, ionizing radiation introduces time-correlated
quasiparticle bursts in resonators on the same chip, further complicating
quantum error correction. Operating in a deep-underground lead-shielded
cryostat decreases the quasiparticle burst rate by a factor fifty and reduces
dissipation up to a factor four, showcasing the importance of radiation
abatement in future solid-state quantum hardware
Rehabilitation for post-stroke cognitive impairment: an overview of recommendations arising from systematic reviews of current evidence
In vitro inhibition of HIV-1 by Met-SDF-1β alone or in combination with antiretroviral drugs
Compounds that can block the CXCR4 chemokine receptor are a promising new class of antiretroviral agents. In these experiments we studied the effect of a modified form of the native stromal cell-derived factor- 1 (SDF-1), Met-SDF-1\u3b2. The in vitro susceptibility of two different CXCR4-tropic HIV-1 strains was determined. Antiviral effect was assessed by the reduction of p24 antigen production in PHA-stimulated peripheral blood mononuclear cells with exposure to the modified SDF-1 molecule. The 50% inhibitory concentrations (IC50) were derived from six separate experiments. The IC50 against the two HIV-1 isolates was in 1.0-2.8 \u3bcg/ml range for Met-SDF-1\u3b2. Met-SDF-1\u3b2 showed synergy to additivity with either zidovudine or nelfinavir at IC75, IC90 and IC95. Additivity was seen when Met-SDF-1\u3b2 was combined with efavirenz. No cellular toxicity was observed at the highest concentrations when these agents were used either singly or in combination. This compound is a promising new candidate in a receptor-based approach to HIV-1 infection in conjunction with currently available combination antiretroviral drug therapies
The CUORE Cryostat: A 1-Ton Scale Setup for Bolometric Detectors
The cryogenic underground observatory for rare events (CUORE) is a 1-ton
scale bolometric experiment whose detector consists of an array of 988 TeO2
crystals arranged in a cylindrical compact structure of 19 towers. This will be
the largest bolometric mass ever operated. The experiment will work at a
temperature around or below 10 mK. CUORE cryostat consists of a cryogen-free
system based on pulse tubes and a custom high power dilution refrigerator,
designed to match these specifications. The cryostat has been commissioned in
2014 at the Gran Sasso National Laboratories and reached a record temperature
of 6 mK on a cubic meter scale. In this paper, we present results of CUORE
commissioning runs. Details on the thermal characteristics and cryogenic
performances of the system will be also given.Comment: 7 pages, 2 figures, LTD16 conference proceedin
Phosph(on)ate as a zinc-binding group in metalloenzyme inhibitors: X-ray crystal structure of the antiviral drug foscarnet complexed to human carbonic anhydrase I
Foscarnet (phosphonoformate trisodium salt), an antiviral used for the treatment of HIV and herpes virus infections, also acts as an activator or inhibitor of the metalloenzyme carbonic anhydrase (CA, EC 4.2.1.1). Interaction of the drug with 11 CA isozymes has been investigated kinetically, and the X-ray structure of its adduct with isoform I (hCA I-foscarnet complex) has been resolved. The first CA inhibitor possessing a phosphonate zinc-binding group is thus evidenced, together with the factors governing recognition of such small molecules by a metalloenzyme active site. Foscarnet is also a clear-cut example of modulator of an enzyme activity which can act either as an activator or inhibitor of a CA isozyme
Cellulose acetate phthalate, a common pharmaceutical excipient, inactivates HIV-1 and blocks the coreceptor binding site on the virus envelope glycoprotein gp120
BACKGROUND: Cellulose acetate phthalate (CAP), a pharmaceutical excipient used for enteric film coating of capsules and tablets, was shown to inhibit infection by the human immunodeficiency virus type 1 (HIV-1) and several herpesviruses. CAP formulations inactivated HIV-1, herpesvirus types 1 (HSV-1) and 2 (HSV-2) and the major nonviral sexually transmitted disease (STD) pathogens and were effective in animal models for vaginal infection by HSV-2 and simian immunodeficiency virus. METHODS: Enzyme-linked immunoassays and flow cytometry were used to demonstrate CAP binding to HIV-1 and to define the binding site on the virus envelope. RESULTS: 1) CAP binds to HIV-1 virus particles and to the envelope glycoprotein gp120; 2) this leads to blockade of the gp120 V3 loop and other gp120 sites resulting in diminished reactivity with HIV-1 coreceptors CXCR4 and CCR5; 3) CAP binding to HIV-1 virions impairs their infectivity; 4) these findings apply to both HIV-1 IIIB, an X4 virus, and HIV-1 BaL, an R5 virus. CONCLUSIONS: These results provide support for consideration of CAP as a topical microbicide of choice for prevention of STDs, including HIV-1 infection
Large-scale wind structures in OB supergiants: a search for rotationally modulated H\alpha variability
We present the results of a long-term monitoring campaign of the H\alpha line
in a sample of bright OB-supergiants (O7.5-B9) that aims at detecting
rotationally modulated changes potentially related to the existence of
large-scale wind structures. A total of 22 objects were monitor ed during 36
nights spread over 6 months in 2001-2002. Coordinated broad-band photometric
observations were also obtained for some targets. Conspicuous evidence for
variability in H\alpha is found for the stars displaying a feature contaminated
by wind emission. Most changes take place on a daily time-scale, although
hourly variations are also occasionally detected. Convincing evidence for a
cyclical pattern of variability in H\alpha has been found in 2 stars: HD 14134
and HD 42087 (periodic signals are also detected in other stars, but
independent confirmation is required). Rotational modulation is suggested from
the similarity between the observed recurrence time-scales (in the range 13-25
days) and estimated periods of stellar rotation. We call attention to the
atypical case of HD 14134 which exhibits a clear 12.8-d periodicity both in the
photometric and in the spectroscopic data sets. This places this object among a
handful of early-type stars where one may observe a clear link between extended
wind structures and photospheric disturbances. Further modelling may test the
hypothesis that azimuthally-extended wind streams are responsible for the
patterns of spectral variability in our target stars.Comment: 18 pages, accepted for publication in MNRA
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