4,513 research outputs found
Towards an Efficient Finite Element Method for the Integral Fractional Laplacian on Polygonal Domains
We explore the connection between fractional order partial differential
equations in two or more spatial dimensions with boundary integral operators to
develop techniques that enable one to efficiently tackle the integral
fractional Laplacian. In particular, we develop techniques for the treatment of
the dense stiffness matrix including the computation of the entries, the
efficient assembly and storage of a sparse approximation and the efficient
solution of the resulting equations. The main idea consists of generalising
proven techniques for the treatment of boundary integral equations to general
fractional orders. Importantly, the approximation does not make any strong
assumptions on the shape of the underlying domain and does not rely on any
special structure of the matrix that could be exploited by fast transforms. We
demonstrate the flexibility and performance of this approach in a couple of
two-dimensional numerical examples
Chronic migraine, comorbidity and socioeconomic deprivation: cross-sectional analysis of a large nationally representative primary care database
Background: Chronic migraine is common but there is limited knowledge on associated comorbidities. Objectives:
To examine mental and physical comorbidities in chronic migraine and the influence of socioeconomic
status in a large, nationally representative dataset. Design: Analysis of cross-sectional primary healthcare data
from 1,468,404 adults in Scotland. Chronic migraine, 31 other physical conditions, and seven mental health conditions
we examined. Prevalence rates were standardized by age groups, sex, and socioeconomic deprivation, and
adjusted odds ratio (aOR) and 95% confidence intervals (CI) calculated for those with chronic migraine compared
with those without. Results: Chronic migraine patients had more conditions, with the biggest difference
found for five or more conditions (chronic migraine 11.7% vs. controls 4.9%; aOR 3.00; 95% CI 2.78–3.22).
Twenty-five of the 31 physical conditions were significantly more prevalent in the chronic migraine group. The
biggest difference was for chronic pain (aOR 4.33; 95% CI 4.12–4.55). For mental health conditions, the biggest
differences were for anxiety (aOR 2.95; 95% CI 2.76–31.5) and depression (aOR 2.94; 95% CI 2.81–3.08).
Increasing deprivation was associated with more severe and complex comorbidity (five or more conditions), and
with more combined mental and physical comorbidity in the chronic migraine group. Conclusions: In a large
nationally representative sample in primary care, comorbidity was most common in those with chronic migraine
compared with standardized controls, and this was exacerbated by living in areas of higher deprivation
Searching for Exoplanets Using a Microresonator Astrocomb
Detection of weak radial velocity shifts of host stars induced by orbiting
planets is an important technique for discovering and characterizing planets
beyond our solar system. Optical frequency combs enable calibration of stellar
radial velocity shifts at levels required for detection of Earth analogs. A new
chip-based device, the Kerr soliton microcomb, has properties ideal for
ubiquitous application outside the lab and even in future space-borne
instruments. Moreover, microcomb spectra are ideally suited for astronomical
spectrograph calibration and eliminate filtering steps required by conventional
mode-locked-laser frequency combs. Here, for the calibration of astronomical
spectrographs, we demonstrate an atomic/molecular line-referenced,
near-infrared soliton microcomb. Efforts to search for the known exoplanet HD
187123b were conducted at the Keck-II telescope as a first in-the-field
demonstration of microcombs
Unique reporter-based sensor platforms to monitor signalling in cells
Introduction: In recent years much progress has been made in the development of tools for systems biology to study the levels of mRNA and protein, and their interactions within cells. However, few multiplexed methodologies are available to study cell signalling directly at the transcription factor level.
<p/>Methods: Here we describe a sensitive, plasmid-based RNA reporter methodology to study transcription factor activation in mammalian cells, and apply this technology to profiling 60 transcription factors in parallel. The methodology uses two robust and easily accessible detection platforms; quantitative real-time PCR for quantitative analysis and DNA microarrays for parallel, higher throughput analysis.
<p/>Findings: We test the specificity of the detection platforms with ten inducers and independently validate the transcription factor activation.
<p/>Conclusions: We report a methodology for the multiplexed study of transcription factor activation in mammalian cells that is direct and not theoretically limited by the number of available reporters
Radio Emission from Ultra-Cool Dwarfs
The 2001 discovery of radio emission from ultra-cool dwarfs (UCDs), the very
low-mass stars and brown dwarfs with spectral types of ~M7 and later, revealed
that these objects can generate and dissipate powerful magnetic fields. Radio
observations provide unparalleled insight into UCD magnetism: detections extend
to brown dwarfs with temperatures <1000 K, where no other observational probes
are effective. The data reveal that UCDs can generate strong (kG) fields,
sometimes with a stable dipolar structure; that they can produce and retain
nonthermal plasmas with electron acceleration extending to MeV energies; and
that they can drive auroral current systems resulting in significant
atmospheric energy deposition and powerful, coherent radio bursts. Still to be
understood are the underlying dynamo processes, the precise means by which
particles are accelerated around these objects, the observed diversity of
magnetic phenomenologies, and how all of these factors change as the mass of
the central object approaches that of Jupiter. The answers to these questions
are doubly important because UCDs are both potential exoplanet hosts, as in the
TRAPPIST-1 system, and analogues of extrasolar giant planets themselves.Comment: 19 pages; submitted chapter to the Handbook of Exoplanets, eds. Hans
J. Deeg and Juan Antonio Belmonte (Springer-Verlag
Corticotropin-releasing hormone, its binding protein and receptors in human cervical tissue at preterm and term labor in comparison to non-pregnant state
BACKGROUND: Preterm birth is still the leading cause of neonatal morbidity and mortality. The level of corticotropin-releasing hormone (CRH) is known to be significantly elevated in the maternal plasma at preterm birth. Although, CRH, CRH-binding protein (CRH-BP), CRH-receptor 1 (CRH-R1) and CRH-R2 have been identified both at mRNA and protein level in human placenta, deciduas, fetal membranes, endometrium and myometrium, no corresponding information is yet available on cervix. Thus, the aim of this study was to compare the levels of the mRNA species coding for CRH, CRH-BP, CRH-R1 and CRH-R2 in human cervical tissue and myometrium at preterm and term labor and not in labor as well as in the non-pregnant state, and to localize the corresponding proteins employing immunohistochemical analysis. METHODS: Cervical, isthmic and fundal (from non-pregnant subjects only) biopsies were taken from 67 women. Subjects were divided in 5 groups: preterm labor (14), preterm not in labor (7), term labor (18), term not in labor (21) and non-pregnant (7). Real-time RT-PCR was employed for quantification of mRNA levels and the corresponding proteins were localized by immunohistochemical analysis. RESULTS: The levels of CRH-BP, CRH-R1 and CRH-R2 mRNA in the pregnant tissues were lower than those in non-pregnant subjects. No significant differences were observed between preterm and term groups. CRH-BP and CRH-R2 mRNA and the corresponding proteins were present at lower levels in the laboring cervix than in the non-laboring cervix, irrespective of gestational age. In most of the samples, with the exception of four myometrial biopsies the level of CRH mRNA was below the limit of detection. All of these proteins could be detected and localized in the cervix and the myometrium by immunohistochemical analysis. CONCLUSION: Expression of CRH-BP, CRH-R1 and CRH-R2 in uterine tissues is down-regulated during pregnancy. The most pronounced down-regulation of CRH-BP and CRH-R2 occurred in laboring cervix, irrespective the length of gestation. The detection of substantial expression of the CRH and its receptor proteins, as well as receptor mRNA in the cervix suggests that the cervix may be a target for CRH action. Further studies are required to elucidate the role of CRH in cervical ripening
Protracted timescales of lower crustal growth at the fast-spreading East Pacific Rise
Author Posting. © The Author(s), 2011. This is the author's version of the work. It is posted here by permission of Nature Publishing Group for personal use, not for redistribution. The definitive version was published in Nature Geoscience 5 (2012): 275-278, doi:10.1038/ngeo1378.Formation of the oceanic crust at mid-ocean ridges is a fundamental component of
plate tectonics. A majority of the crust at many ridges is composed of plutonic rocks
that form by crystallization of mantle-derived magmas within the crust. Recent
application of U/Pb dating to samples from in-situ oceanic crust has begun to
provide exciting new insight into the timing, duration and distribution of
magmatism during formation of the plutonic crust1-4. Previous studies have focused
on samples from slow-spreading ridges, however, the time scales and processes of
crustal growth are expected to vary with plate spreading rate. Here we present the
first high-precision dates from plutonic crust formed at the fast-spreading East
Pacific Rise (EPR). Individual zircon minerals yielded dates from 1.420–1.271
million years ago, with uncertainties of ± 0.006–0.081 million years. Within
individual samples, zircons record a range of dates of up to ~0.124 million years,
consistent with protracted crystallization or assimilation of older zircons from
adjacent rocks. The variability in dates is comparable to data from the Vema
lithospheric section on the Mid-Atlantic Ridge (MAR)3, suggesting that time scales
of magmatic processes in the lower crust may be similar at slow- and fast-spreading
ridges.This research was partially funded by NSF grant OCE-0727914 (SAB), a Cardiff
University International Collaboration Award (CJL) and NERC grant NE/C509023/1
(CJM).2012-07-2
Fin-Tail Coordination during Escape and Predatory Behavior in Larval Zebrafish
Larval zebrafish innately perform a suite of behaviors that are tightly linked to their evolutionary past, notably escape from threatening stimuli and pursuit and capture of prey. These behaviors have been carefully examined in the past, but mostly with regard to the movements of the trunk and tail of the larvae. Here, we employ kinematics analyses to describe the movements of the pectoral fins during escape and predatory behavior. In accord with previous studies, we find roles for the pectoral fins in slow swimming and immediately after striking prey. We find novel roles for the pectoral fins in long-latency, but not in short-latency C-bends. We also observe fin movements that occur during orienting J-turns and S-starts that drive high-velocity predatory strikes. Finally, we find that the use of pectoral fins following a predatory strike is scaled to the velocity of the strike, supporting a role for the fins in braking. The implications of these results for central control of coordinated movements are discussed, and we hope that these results will provide baselines for future analyses of cross-body coordination using mutants, morphants, and transgenic approaches
Evidence for the Decay
We present a search for the ``wrong-sign'' decay D0 -> K+ pi- pi+ pi- using 9
fb-1 of e+e- collisions on and just below the Upsilon(4S) resonance. This decay
can occur either through a doubly Cabibbo-suppressed process or through mixing
to a D0bar followed by a Cabibbo-favored process. Our result for the
time-integrated wrong-sign rate relative to the decay D0 -> K- pi+ pi- pi+ is
(0.0041 +0.0012-0.0011(stat.) +-0.0004(syst.))x(1.07 +-0.10)(phase space),
which has a statistical significance of 3.9 standard deviations.Comment: 9 pages postscript, also available through
http://w4.lns.cornell.edu/public/CLNS, submitted to PR
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