392 research outputs found
Phase-coherent repetition rate multiplication of a mode-locked laser from 40 MHz to 1 GHz by injection locking
We have used injection locking to multiply the repetition rate of a passively
mode-locked femtosecond fiber laser from 40 MHz to 1 GHz while preserving
optical phase coherence between the master laser and the slave output. The
system is implemented almost completely in fiber and incorporates gain and
passive saturable absorption. The slave repetition rate is set to a rational
harmonic of the master repetition rate, inducing pulse formation at the least
common multiple of the master and slave repetition rates
Psychometric Properties Of Responses By Clinicians And Older Adults To A 6-Item Hebrew Version Of The Hamilton Depression Rating Scale (HAM-D6)
Background
The Hamilton Depression Rating Scale (HAM-D) is commonly used as a screening instrument, as a continuous measure of change in depressive symptoms over time, and as a means to compare the relative efficacy of treatments. Among several abridged versions, the 6-item HAM-D6 is used most widely in large degree because of its good psychometric properties. The current study compares both self-report and clinician-rated versions of the Hebrew version of this scale.
Methods
A total of 153 Israelis 75 years of age on average participated in this study. The HAM-D6 was examined using confirmatory factor analytic (CFA) models separately for both patient and clinician responses.
Results
Reponses to the HAM-D6 suggest that this instrument measures a unidimensional construct with each of the scales’ six items contributing significantly to the measurement. Comparisons between self-report and clinician versions indicate that responses do not significantly differ for 4 of the 6 items. Moreover, 100% sensitivity (and 91% specificity) was found between patient HAM-D6 responses and clinician diagnoses of depression.
Conclusion
These results indicate that the Hebrew HAM-D6 can be used to measure and screen for depressive symptoms among elderly patients
Realization of a complete Stern-Gerlach interferometer: Toward a test of quantum gravity
The Stern-Gerlach effect, found a century ago, has become a paradigm of quantum mechanics. Unexpectedly, until recently, there has been little evidence that the original scheme with freely propagating atoms exposed to gradients from macroscopic magnets is a fully coherent quantum process. Several theoretical studies have explained why a Stern-Gerlach interferometer is a formidable challenge. Here, we provide a detailed account of the realization of a full-loop Stern-Gerlach interferometer for single atoms and use the acquired understanding to show how this setup may be used to realize an interferometer for macroscopic objects doped with a single spin. Such a realization would open the door to a new era of fundamental probes, including the realization of previously inaccessible tests at the interface of quantum mechanics and gravity
T^3-Stern-Gerlach Matter-Wave Interferometer
We present a unique matter-wave interferometer whose phase scales with the
cube of the time the atom spends in the interferometer. Our scheme is based on
a full-loop Stern-Gerlach interferometer incorporating four magnetic field
gradient pulses to create a state-dependent force. In contrast to typical atom
interferometers which make use of laser light for the splitting and
recombination of the wave packets, this realization uses no light and can
therefore serve as a high-precision surface probe at very close distances.Comment: Phys. Rev. Lett., in print, https://journals.aps.org/prl
T 3 Stern-Gerlach matter-wave interferometer
The article of record as published may be found at https://doi.org/10.1103/PhysRevLett.123.083601We present a unique matter-wave interferometer whose phase scales with the cube of the time the atom spends in the interferometer. Our scheme is based on a full-loop Stern-Gerlach interferometer incorporating four magnetic field gradient pulses to create a state-dependent force. In contrast to typical atom interferometers which make use of laser light for the splitting and recombination of the wave packets, this realization uses no light and can therefore serve as a high-precision surface probe at very close distances.This work is funded in part by the Israel Science Foundation (grant No. 856/18) and the German- Israeli DIP projects (Hybrid devices: FO 703/2-1, AR 924/1-1, DU 1086/2-1) supported by the DFG. We also acknowledge support from the Israeli Council for Higher Education (Israel). M.A.E. is thankful to the Center for Integrated Quantum Science and Technology (IQST ) for its generous financial support. W.P.S. is grateful to Texas A&M University for a Faculty Fellowship at the Hagler Institute for Advanced Study at Texas A&M University, and to Texas A&M AgriLife Research for the support of this work. The research of the IQST is financially supported by the Ministry of Science, Research and Arts, Baden-Wurttemberg. F.A.N. is grateful for a generous Laboratory University Collaboration Initiative (LUCI) grant from the Office of the Secretary of Defense.This work is funded in part by the Israel Science Foundation (grant No. 856/18) and the German- Israeli DIP projects (Hybrid devices: FO 703/2-1, AR 924/1-1, DU 1086/2-1) supported by the DFG. We also acknowledge support from the Israeli Council for Higher Education (Israel). M.A.E. is thankful to the Center for Integrated Quantum Science and Technology (IQST ) for its generous financial support. W.P.S. is grateful to Texas A&M University for a Faculty Fellowship at the Hagler Institute for Advanced Study at Texas A&M University, and to Texas A&M AgriLife Research for the support of this work. The research of the IQST is financially supported by the Ministry of Science, Research and Arts, Baden-Wurttemberg. F.A.N. is grateful for a generous Laboratory University Collaboration Initiative (LUCI) grant from the Office of the Secretary of Defense
Spatial and topological organization of DNA chains induced by gene co-localization
Transcriptional activity has been shown to relate to the organization of
chromosomes in the eukaryotic nucleus and in the bacterial nucleoid. In
particular, highly transcribed genes, RNA polymerases and transcription factors
gather into discrete spatial foci called transcription factories. However, the
mechanisms underlying the formation of these foci and the resulting topological
order of the chromosome remain to be elucidated. Here we consider a
thermodynamic framework based on a worm-like chain model of chromosomes where
sparse designated sites along the DNA are able to interact whenever they are
spatially close-by. This is motivated by recurrent evidence that there exists
physical interactions between genes that operate together. Three important
results come out of this simple framework. First, the resulting formation of
transcription foci can be viewed as a micro-phase separation of the interacting
sites from the rest of the DNA. In this respect, a thermodynamic analysis
suggests transcription factors to be appropriate candidates for mediating the
physical interactions between genes. Next, numerical simulations of the polymer
reveal a rich variety of phases that are associated with different topological
orderings, each providing a way to increase the local concentrations of the
interacting sites. Finally, the numerical results show that both
one-dimensional clustering and periodic location of the binding sites along the
DNA, which have been observed in several organisms, make the spatial
co-localization of multiple families of genes particularly efficient.Comment: Figures and Supplementary Material freely available on
http://dx.doi.org/10.1371/journal.pcbi.100067
Nucleic Acids Res
Cells adapt to environmental changes by efficiently adjusting gene expression programs. Staphylococcus aureus, an opportunistic pathogenic bacterium, switches between defensive and offensive modes in response to quorum sensing signal. We identified and studied the structural characteristics and dynamic properties of the core regulatory circuit governing this switch by deterministic and stochastic computational methods, as well as experimentally. This module, termed here Double Selector Switch (DSS), comprises the RNA regulator RNAIII and the transcription factor Rot, defining a double-layered switch involving both transcriptional and post-transcriptional regulations. It coordinates the inverse expression of two sets of target genes, immuno-modulators and exotoxins, expressed during the defensive and offensive modes, respectively. Our computational and experimental analyses show that the DSS guarantees fine-tuned coordination of the inverse expression of its two gene sets, tight regulation, and filtering of noisy signals. We also identified variants of this circuit in other bacterial systems, suggesting it is used as a molecular switch in various cellular contexts and offering its use as a template for an effective switching device in synthetic biology studies
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