541 research outputs found
Random matrix approach in search for weak signals immersed in background noise
We present new, original and alternative method for searching signals coded
in noisy data. The method is based on the properties of random matrix
eigenvalue spectra. First, we describe general ideas and support them with
results of numerical simulations for basic periodic signals immersed in
artificial stochastic noise. Then, the main effort is put to examine the
strength of a new method in investigation of data content taken from the real
astrophysical NAUTILUS detector, searching for the presence of gravitational
waves. Our method discovers some previously unknown problems with data
aggregation in this experiment. We provide also the results of new method
applied to the entire respond signal from ground based detectors in future
experimental activities with reduced background noise level. We indicate good
performance of our method what makes it a positive predictor for further
applications in many areas.Comment: 15 pages, 16 figure
Multifractal detrending moving average cross-correlation analysis
There are a number of situations in which several signals are simultaneously
recorded in complex systems, which exhibit long-term power-law
cross-correlations. The multifractal detrended cross-correlation analysis
(MF-DCCA) approaches can be used to quantify such cross-correlations, such as
the MF-DCCA based on detrended fluctuation analysis (MF-X-DFA) method. We
develop in this work a class of MF-DCCA algorithms based on the detrending
moving average analysis, called MF-X-DMA. The performances of the MF-X-DMA
algorithms are compared with the MF-X-DFA method by extensive numerical
experiments on pairs of time series generated from bivariate fractional
Brownian motions, two-component autoregressive fractionally integrated moving
average processes and binomial measures, which have theoretical expressions of
the multifractal nature. In all cases, the scaling exponents extracted
from the MF-X-DMA and MF-X-DFA algorithms are very close to the theoretical
values. For bivariate fractional Brownian motions, the scaling exponent of the
cross-correlation is independent of the cross-correlation coefficient between
two time series and the MF-X-DFA and centered MF-X-DMA algorithms have
comparative performance, which outperform the forward and backward MF-X-DMA
algorithms. We apply these algorithms to the return time series of two stock
market indexes and to their volatilities. For the returns, the centered
MF-X-DMA algorithm gives the best estimates of since its
is closest to 0.5 as expected, and the MF-X-DFA algorithm has the
second best performance. For the volatilities, the forward and backward
MF-X-DMA algorithms give similar results, while the centered MF-X-DMA and the
MF-X-DFA algorithms fails to extract rational multifractal nature.Comment: 15 pages, 4 figures, 2 matlab codes for MF-X-DMA and MF-X-DF
Differential risk of ST-Segment Elevation Myocardial Infarction in male and female smokers
Background
Smoking is a well-documented risk for acute ST-segment elevation myocardial infarction (STEMI). The differential effect between sexes has yet to be quantified.
Objectives
The purpose of this study was to differentiate the effect of smoking on increased risk of STEMI between sexes.
Methods
For this retrospective ecological cohort study, all patients at a U.K. tertiary cardiothoracic center who presented between 2009 and 2014 with acute STEMI were combined with population data to generate incidence rates of STEMI. Age-standardized incidence rate ratios (IRRs) using the Poisson distribution were calculated comparing STEMI rates between smokers and nonsmokers stratified by sex and 3 age groups (18 to 49, 50 to 64, and >65 years).
Results
A total of 3,343 patients presented over 5,639,328 person-years. Peak STEMI rate for current smokers was in the 70 to 79 years age range for women (235 per 100,000 patient-years) and 50 to 59 years (425 per 100,000 patient-years) in men. Smoking was associated with a significantly greater increase in STEMI rate for women than men (IRR: 6.62; 95% confidence interval [CI]: 5.98 to 7.31, vs. 4.40; 95% CI: 4.15 to 4.67). The greatest increased risk was in women age 18 to 49 (IRR: 13.22; 95% CI: 10.33 to 16.66, vs. 8.60; 95% CI: 7.70 to 9.59 in men). The greatest risk difference was in the age 50 to 64 years group, with IRR of 9.66 (95% CI: 8.30 to 11.18) in women and 4.47 (95% CI: 4.10 to 4.86) in men.
Conclusions
This study quantifies the differential effect of smoking between sexes, with women having a significantly increased risk of STEMI than men. This information encourages continued efforts to prevent smoking uptake and promote cessation
An investigation of the effects of stage of ensilage on Nassella neesiana seeds, for reducing seed viability and injury to livestock
The noxious weed Nassella neesiana is established on a wide range of productive land throughout southeastern Australia. N. neesiana seeds, when mature, are sharp, causing injury to livestock, thus posing a problem in fodder bales. To reduce infestations of agricultural weeds in situ, production of silage from weed-infested pastures is practised as part of integrated weed management (IWM). However, there is little data to demonstrate whether this process is useful to reduce infestations or the harmful properties of N. neesiana. Therefore, the minimum duration of ensilage required to reduce the viability of N. neesiana seeds was investigated, both with and without addition of ensilage inoculants in this process. Also, the decreasing propensity of the seeds to injure livestock, after various times and conditions of ensilage, was assessed. Ensilage inoculant reduced seed germination probability to zero after 35 days. When no inoculant was added, zero viability was achieved after 42 days. A qualitative assessment of the hardness of ensilaged seeds found seed husks were softer (and therefore safer) after 42 days, whether inoculant was used or not. Therefore, we suggest that both the viability of N. neesiana seeds and hardness of seed casings are significantly reduced after 42 days, thereby reducing the risks of seed dispersal and injury to livestock
Calcium-phosphate derived from mineralized algae for bone tissue engineering applications
In this work, several routes are described towards obtaining pure inorganic phases derived from Coralline officinallis red algae. The scanning
electron microscopy studies have shown that it becomes possible not only to eliminate the undesired organic phase, but also to preserve or tailor
the red algae typical microporosity. X-ray diffraction analysis was used to investigate the phase content of the red algae before and after
performing the different treatment routes. Hydroxyapatite nanocrystallites were obtained after converting the coralline calcium carbonate skeleton
by means of combining thermal and chemical routes. These results were confirmed by Fourier transform infra-red spectroscopic analysis. The
processing routes herein described are very promising in order to design bioceramics of algae origin that might find useful applications as bone
fillers and tissue engineering scaffolds
Increased Thymic B Cells but Maintenance of Thymic Structure, T Cell Differentiation and Negative Selection in Lymphotoxin-α and TNF Gene-Targeted Mice
TNF, lymphotoxin (LT) and their receptors are expressed constitutively in the thymus. It
remains unclear whether these cytokines play a role in normal thymic structure or function.
We have investigated thymocyte differentiation, selection and thymic organogenesis in gene
targeted mice lacking LTα, TNF, or both (TNF/LTα-/-). The thymus was normal in
TNF/LTα-/- mice with regard to cell yields and stromal architecture. Detailed analysis of αβ
and γδ T cell-lineage thymocyte subsets revealed no abnormalities, implying that neither TNF
nor LT play an essential role in T cell differentiation or positive selection. The number and
distribution of thymic CD11c+ dendritic cells was also normal in the absence of both TNF and
LTα. A three-fold increase in B cell numbers was observed consistently in the TNF/LTα-/-
thymus. This phenotype was due entirely to the LTα deficiency and associated with changes
in the hemopoietic compartment, rather than the thymic stromal compartment of LTα-/- mice.
Finally, specific Vβ8+ T cell deletion within the thymus following intrathymic injection of
staphylococcal enterotoxin B (SEB) was TNF/LT independent. Thus, despite the presence of
these cytokines and their receptors in the normal thymus, there appears no essential role for
either TNF or LT in development of organ structure or for those processes associated with T
cell repertoire selection
The excitation spectrum for weakly interacting bosons in a trap
We investigate the low-energy excitation spectrum of a Bose gas confined in a
trap, with weak long-range repulsive interactions. In particular, we prove that
the spectrum can be described in terms of the eigenvalues of an effective
one-particle operator, as predicted by the Bogoliubov approximation.Comment: LaTeX, 32 page
Anomalous Self-Generated Electrostatic Fields in Nanosecond Laser-Plasma Interaction
Electrostatic (E) fields associated with the interaction of a
well-controlled, high-power, nanosecond laser pulse with an underdense plasma
are diagnosed by proton radiography. Using a current 3D wave propagation code
equipped with nonlinear and nonlocal hydrodynamics, we can model the measured
E-fields that are driven by the laser ponderomotive force in the region where
the laser undergoes filamentation. However, strong fields of up to 110 MV/m
measured in the first millimeter of propagation cannot be reproduced in the
simulations. This could point to the presence of unexpected strong thermal
electron pressure gradients possibly linked to ion acoustic turbulence, thus
emphasizing the need for the development of full kinetic collisional
simulations in order to properly model laser-plasma interaction in these
strongly nonlinear conditions.Comment: 12 pages, 4 figures, submitted to Physics of Plasma
Evaluating the Phenotypic Patterns of Post-Traumatic Headache:A Systematic Review of Military Personnel
Introduction: Mild traumatic brain injury (TBI) affects a significant number of military personnel, primarily because of physical impact, vehicle incidents, and blast exposure. Post-traumatic headache (PTH) is the most common symptom reported following mild TBI and can persist for several years. However, the current International Classification of Headache Disorders lacks phenotypic characterization for this specific headache disorder. It is important to appropriately classify the headache sub-phenotypes as it may enable more targeted management approaches. This systematic review seeks to identify the most common sub-phenotype of headaches in military personnel with PTH attributed to mild TBI.Methods: We conducted a systematic search following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses reporting guidelines, focusing on the military population. PubMed, Web of Science, Cochrane, and Clinicaltrials.gov databases were searched. Abstracts and full texts were independently reviewed by two authors using predefined inclusion and exclusion criteria. Data extraction was performed using a standardized form. The risk of bias was assessed using the Newcastle-Ottawa Scale.Results: Eight papers related to the military population were included in this review. Migraine was the most commonly reported headache sub-phenotype, with a prevalence ranging from 33 to 92%. Additionally, one military study identified tension-type headaches as the most prevalent headache phenotype. Although not the primary phenotype, one military cohort reported that approximately one-third of their cohort experienced trigeminal autonomic cephalalgias, which were associated with exposure to blast injuries and prior concussions.Conclusion: This systematic review demonstrated that PTH in the military population frequently exhibit migraine-like features. Tension-type headache and trigeminal autonomic cephalalgias also occur, although less commonly reported. Sub-phenotyping PTH may be important for initiating effective treatment since different phenotypes may respond differently to medications. The study populations analyzed in this systematic review display heterogeneity, underscoring the necessity for additional research features, more stringent criteria and comprehensive recording of baseline characteristics. Characterizing headaches following injury is crucial for an accurate diagnosis to enable effective management and rehabilitation planning for our armed forces
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