230 research outputs found
Suppression of stimulated Brillouin scattering in optical fibers using a linearly chirped diode laser
The output of high power fiber amplifiers is typically limited by stimulated Brillouin scattering (SBS). An analysis of SBS with a chirped pump laser indicates that a chirp of 2.5 Ă 10^(15) Hz/s could raise, by an order
of magnitude, the SBS threshold of a 20-m fiber. A diode laser with a constant output power and a linear chirp of 5 Ă 10^(15) Hz/s has been previously demonstrated. In a low-power proof-of-concept experiment, the threshold for SBS in a 6-km fiber is increased by a factor of 100 with a
chirp of 5 Ă 10^(14) Hz/s. A linear chirp will enable straightforward coherent combination of multiple fiber amplifiers, with electronic compensation of path length differences on the order of 0.2 m
The outcome of 41 Late-Diagnosed Turkish GA-1 Patients: A Candidate for the Turkish NBS
Background: Glutaric aciduria type 1(GA-1) is an inherited cerebral organic aciduria.
Untreated patients with GA-1 have a risk of acute encephalopathic crises during the first
6 years of life. In so far as GA-1 desperately does not exist in Turkish newborn screening
(NBS) program, most patients in our study were late-diagnosed. /
Method: This study included 41 patients diagnosed with acylcarnitine profile, urinary
organic acids, mutation analyses in the symptomatic period. We presented with
clinical, neuroradiological, and molecular data of our 41 patients. /
Results: The mean age at diagnosis was 14.8 13.9 (15 days to 72 months) and, high
blood glutaconic acid, glutarylcarnitine and urinary glutaric acid (GA) levels in 41
patients were revealed. Seventeen different mutations in the glutaryl-CoA dehydrogenase gene were identified, five of which were novel. The patients, most of whom were
late-diagnosed, had a poor neurological outcome. Treatment strategies made a little
improvement in dystonia and the frequency of encephalopathic attacks. /
Conclusion: All GA-1 patients in our study were severely affected since they were latediagnosed, while others show that GA-1 is a treatable metabolic disorder if it is
diagnosed with NBS. This study provides an essential perspective of the severe impact
on GA-1 patients unless it is diagnosed with NBS. We immediately advocate GA-1 to be
included in the Turkish NBS
Dynamics of Three Agent Games
We study the dynamics and resulting score distribution of three-agent games
where after each competition a single agent wins and scores a point. A single
competition is described by a triplet of numbers , and denoting the
probabilities that the team with the highest, middle or lowest accumulated
score wins. We study the full family of solutions in the regime, where the
number of agents and competitions is large, which can be regarded as a
hydrodynamic limit. Depending on the parameter values , we find six
qualitatively different asymptotic score distributions and we also provide a
qualitative understanding of these results. We checked our analytical results
against numerical simulations of the microscopic model and find these to be in
excellent agreement. The three agent game can be regarded as a social model
where a player can be favored or disfavored for advancement, based on his/her
accumulated score. It is also possible to decide the outcome of a three agent
game through a mini tournament of two-a gent competitions among the
participating players and it turns out that the resulting possible score
distributions are a subset of those obtained for the general three agent-games.
We discuss how one can add a steady and democratic decline rate to the model
and present a simple geometric construction that allows one to write down the
corresponding score evolution equations for -agent games
Clinical features of 27 Turkish Propionic acidemia patients with 12 novel mutations
Propionic acidemia (PA) is an inherited metabolic disease caused by the deficiency of one of the four biotin-dependent enzymes propionyl-CoA carboxylase (PCC), and is characterized by coma and death in unrecognized patients, additionally late diagnosis leads to severe developmental delay and neurological sequels. Manifestations of PA over time can include growth impairment, intellectual disability, seizures, basal ganglia lesions, pancreatitis, and cardiomyopathy. Other rarely reported complications include optic atrophy, hearing loss, premature ovarian insufficiency, and chronic renal failure. Mutations in PCCA-PCCB genes cause the clinically heterogeneous disease of PA. In this study, we investigate the mutation spectrum of PCCAPCCB genes and phenotypic features of 27 Turkish patients with PA from the South and Southeast parts of Turkey. We report 12 novel PA mutations, five affecting the PCCA gene and 7 affecting the PCCB gene
Determining Pair Interactions from Structural Correlations
We examine metastable configurations of a two-dimensional system of
interacting particles on a quenched random potential landscape and ask how the
configurational pair correlation function is related to the particle
interactions and the statistical properties of the potential landscape.
Understanding this relation facilitates quantitative studies of magnetic flux
line interactions in type II superconductors, using structural information
available from Lorentz microscope images or Bitter decorations.
Previous work by some of us supported the conjecture that the relationship
between pair correlations and interactions in pinned flux line ensembles is
analogous to the corresponding relationship in the theory of simple liquids.
The present paper aims at a more thorough understanding of this relation. We
report the results of numerical simulations and present a theory for the low
density behavior of the pair correlation function which agrees well with our
simulations and captures features observed in experiments. In particular, we
find that the resulting description goes beyond the conjectured classical
liquid type relation and we remark on the differences.Comment: 7 pages, 6 figures. See also http://rainbow.uchicago.edu/~grier
Archimedean-like colloidal tilings on substrates with decagonal and tetradecagonal symmetry
Two-dimensional colloidal suspensions subject to laser interference patterns
with decagonal symmetry can form an Archimedean-like tiling phase where rows of
squares and triangles order aperiodically along one direction [J. Mikhael et
al., Nature 454, 501 (2008)]. In experiments as well as in Monte-Carlo and
Brownian dynamics simulations, we identify a similar phase when the laser field
possesses tetradecagonal symmetry. We characterize the structure of both
Archimedean-like tilings in detail and point out how the tilings differ from
each other. Furthermore, we also estimate specific particle densities where the
Archimedean-like tiling phases occur. Finally, using Brownian dynamics
simulations we demonstrate how phasonic distortions of the decagonal laser
field influence the Archimedean-like tiling. In particular, the domain size of
the tiling can be enlarged by phasonic drifts and constant gradients in the
phasonic displacement. We demonstrate that the latter occurs when the
interfering laser beams are not adjusted properly
The Information Coded in the Yeast Response Elements Accounts for Most of the Topological Properties of Its Transcriptional Regulation Network
The regulation of gene expression in a cell relies to a major extent on transcription factors, proteins which recognize and bind the DNA at specific binding sites (response elements) within promoter regions associated with each gene. We present an information theoretic approach to modeling transcriptional regulatory networks, in terms of a simple âsequence-matchingâ rule and the statistics of the occurrence of binding sequences of given specificity in random promoter regions. The crucial biological input is the distribution of the amount of information coded in these cognate response elements and the length distribution of the promoter regions. We provide an analysis of the transcriptional regulatory network of yeast Saccharomyces cerevisiae, which we extract from the available databases, with respect to the degree distributions, clustering coefficient, degree correlations, rich-club coefficient and the k-core structure. We find that these topological features are in remarkable agreement with those predicted by our model, on the basis of the amount of information coded in the interaction between the transcription factors and response elements
A sequence variant at 4p16.3 confers susceptibility to urinary bladder cancer
To access publisher full text version of this article. Please click on the hyperlink in Additional Links fieldPreviously, we reported germline DNA variants associated with risk of urinary bladder cancer (UBC) in Dutch and Icelandic subjects. Here we expanded the Icelandic sample set and tested the top 20 markers from the combined analysis in several European case-control sample sets, with a total of 4,739 cases and 45,549 controls. The T allele of rs798766 on 4p16.3 was found to associate with UBC (odds ratio = 1.24, P = 9.9 x 10(-12)). rs798766 is located in an intron of TACC3, 70 kb from FGFR3, which often harbors activating somatic mutations in low-grade, noninvasive UBC. Notably, rs798766[T] shows stronger association with low-grade and low-stage UBC than with more aggressive forms of the disease and is associated with higher risk of recurrence in low-grade stage Ta tumors. The frequency of rs798766[T] is higher in Ta tumors that carry an activating mutation in FGFR3 than in Ta tumors with wild-type FGFR3. Our results show a link between germline variants, somatic mutations of FGFR3 and risk of UBC.info:eu-repo/grantAgreement/EC/FP7/21807
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