3,507 research outputs found
Forecasts in a Slightly Misspecified Finite Order VAR
We propose a Bayesian procedure for exploiting small, possibly long-lag linear predictability in the innovations of a finite order autoregression. We model the innovations as having a log-spectral density that is a continuous mean-zero Gaussian process of order 1/√T. This local embedding makes the problem asymptotically a normal-normal Bayes problem, resulting in closed-form solutions for the best forecast. When applied to data on 132 U.S. monthly macroeconomic time series, the method is found to improve upon autoregressive forecasts by an amount consistent with the theoretical and Monte Carlo calculations.
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Nearly Optimal Tests When a Nuisance Parameter Is Present Under the Null Hypothesis
This paper considers nonstandard hypothesis testing problems that involve a nuisance parameter. We establish an upper bound on the weighted average power of all
valid tests, and develop a numerical algorithm that determines a feasible test with
power close to the bound. The approach is illustrated in six applications: inference
about a linear regression coefficient when the sign of a control coefficient is known;
small sample inference about the difference in means from two independent Gaussian samples from populations with potentially different variances; inference about the
break date in structural break models with moderate break magnitude; predictability
tests when the regressor is highly persistent; inference about an interval identified parameter; and inference about a linear regression coefficient when the necessity of a
control is in doub
Очистка сточных вод от тяжелых металлов природными сорбентами
Использование отходов подсолнечной лузги позволяет комплексно решить проблему утилизации сельскохозяйственных отходов и получения хемосорбента для очистки сточных вод промышленного производства от ионов тяжелых металлов. Проведены исследования по оценке адсорбционной способности материалов, определены кинетические зависимости процесса.The use of sunflower husk waste allows to solve the problem of utilization of agricultural waste and obtaining chemisorbent for wastewater treatment of industrial production from ions of heavy metals. Studies on the evaluation of the adsorption capacity of materials have been carried out, the kinetic dependencies of the process
Heart Rate Reduction by Ivabradine Improves Aortic Compliance in Apolipoprotein E-Deficient Mice
Background: Impaired vascular compliance is associated with cardiovascular mortality. The effects of heart rate on vascular compliance are unclear. Therefore, we characterized effects of heart rate reduction (HRR) by I(f) current inhibition on aortic compliance and underlying molecular mechanisms in apolipoprotein E-deficient (ApoE–/–) mice. Methods: ApoE–/– mice fed a high-cholesterol diet and wild-type (WT) mice were treated with ivabradine (20 mg/kg/d) or vehicle for 6 weeks. Compliance of the ascending aorta was evaluated by MRI. Results: Ivabradine reduced heart rate by 113 ± 31 bpm (∼19%) in WT mice and by 133 ± 6 bpm (∼23%) in ApoE–/– mice. Compared to WT controls, ApoE–/– mice exhibited reduced distensibility and circumferential strain. HRR by ivabradine increased distensibility and circumferential strain in ApoE–/– mice but did not affect both parameters in WT mice. Ivabradine reduced aortic protein and mRNA expression of the angiotensin II type 1 (AT1) receptor and reduced rac1-GTPase activity in ApoE–/– mice. Moreover, membrane translocation of p47phox was inhibited. In ApoE–/– mice, HRR induced anti-inflammatory effects by reduction of aortic mRNA expression of IL-6, TNF-alpha and TGF-beta. Conclusion: HRR by ivabradine improves vascular compliance in ApoE–/– mice. Contributing mechanisms include downregulation of the AT1 receptor, attenuation of oxidative stress and modulation of inflammatory cytokine expression
Exponential Size Distribution of von Willebrand Factor
AbstractVon Willebrand Factor (VWF) is a multimeric protein crucial for hemostasis. Under shear flow, it acts as a mechanosensor responding with a size-dependent globule-stretch transition to increasing shear rates. Here, we quantify for the first time, to our knowledge, the size distribution of recombinant VWF and VWF-eGFP using a multilateral approach that involves quantitative gel analysis, fluorescence correlation spectroscopy, and total internal reflection fluorescence microscopy. We find an exponentially decaying size distribution of multimers for recombinant VWF as well as for VWF derived from blood samples in accordance with the notion of a step-growth polymerization process during VWF biosynthesis. The distribution is solely described by the extent of polymerization, which was found to be reduced in the case of the pathologically relevant mutant VWF-IIC. The VWF-specific protease ADAMTS13 systematically shifts the VWF size distribution toward smaller sizes. This dynamic evolution is monitored using fluorescence correlation spectroscopy and compared to a computer simulation of a random cleavage process relating ADAMTS13 concentration to the degree of VWF breakdown. Quantitative assessment of VWF size distribution in terms of an exponential might prove to be useful both as a valuable biophysical characterization and as a possible disease indicator for clinical applications
Dissecting the knee - Air shower measurements with KASCADE
Recent results of the KASCADE air shower experiment are presented in order to
shed some light on the astrophysics of cosmic rays in the region of the knee in
the energy spectrum. The results include investigations of high-energy
interactions in the atmosphere, the analysis of the arrival directions of
cosmic rays, the determination of the mean logarithmic mass, and the unfolding
of energy spectra for elemental groups
Identification of an ADAMTS2 frameshift variant in a cat family with Ehlers-Danlos syndrome.
We investigated four European domestic shorthair kittens with skin lesions consistent with the dermatosparaxis type of the Ehlers-Danlos syndrome (EDS), a connective tissue disorder. The kittens were sired by the same tomcat, but were born by three different mothers. The kittens had easily torn skin resulting in non-healing skin wounds. Both clinically and histologically, the skin showed thin epidermis in addition to inflammatory changes. Changes in collagen fibers were visible in electron micrographs. The complete genome of an affected kitten was sequenced. A one base pair duplication leading to a frameshift in the candidate gene ADAMTS2 was identified, p.(Ser235fs*3). All four affected cats carried the frameshift duplication in a homozygous state. Genotypes at this variant showed perfect co-segregation with the autosomal recessive EDS phenotype in the available family. The mutant allele did not occur in 48 unrelated control cats. ADAMTS2 loss-of-function variants cause autosomal recessive forms of EDS in humans, mice, dogs, cattle and sheep. The available evidence from our investigation together with the functional knowledge on ADAMTS2 in other species allow to classify the identified ADAMTS2 variant as pathogenic and most likely causative variant for the observed EDS
Can quantitative sensory tests predict failed back surgery?:A prospective cohort study
BACKGROUND
Failed back surgery syndrome (FBSS) is a pain condition refractory to therapy, and is characterised by persistent low back pain after spinal surgery. FBSS is associated with severe disability, low quality of life and high unemployment. We are currently unable to identify patients who are at risk of developing FBSS. Patients with chronic low back pain may display signs of central hypersensitivity as assessed by quantitative sensory tests (QST). This can contribute to the risk of developing persistent pain after surgery.
OBJECTIVE
We tested the hypothesis that central hypersensitivity as assessed by QST predicts FBSS.
DESIGN
Prospective cohort study.
SETTING
Three tertiary care centres.
PATIENTS
141 patients scheduled for up to three segment spinal surgery for chronic low back pain (defined as at least 3 on a numerical rating scale on most days during the week and with a minimum duration of 3 months) due to degenerative changes.
OUTCOMES
We defined FBSS as persistent pain, persistent disability or a composite outcome defined as either persistent pain or disability. The primary outcome was persistent pain 12 months after surgery. We applied 14 QST using electrical, pressure and temperature stimulation to predict FBSS and assessed the association of QST with FBSS in multivariable analyses adjusted for sociodemographic, psychological and clinical and surgery-related characteristics.
RESULTS
None of the investigated 14 QST predicted FBSS, with 95% confidence intervals of crude and adjusted associations of all QST including one as a measure of no association. Results remained robust in all sensitivity and secondary analyses.
CONCLUSION
The study indicates that assessment of altered central pain processing using current QST is unlikely to identify patients at risk of FBSS and is therefore unlikely to inform clinical decisions
Cosmic Ray Energy Spectra and Mass Composition at the Knee - Recent Results from KASCADE -
Recent results from the KASCADE experiment on measurements of cosmic rays in
the energy range of the knee are presented. Emphasis is placed on energy
spectra of individual mass groups as obtained from an two-dimensional unfolding
applied to the reconstructed electron and truncated muon numbers of each
individual EAS. The data show a knee-like structure in the energy spectra of
light primaries (p, He, C) and an increasing dominance of heavy ones (A > 20)
towards higher energies. This basic result is robust against uncertainties of
the applied interaction models QGSJET and SIBYLL which are used in the shower
simulations to analyse the data. Slight differences observed between
experimental data and EAS simulations provide important clues for further
improvements of the interaction models. The data are complemented by new limits
on global anisotropies in the arrival directions of CRs and by upper limits on
point sources. Astrophysical implications for discriminating models of maximum
acceleration energy vs galactic diffusion/drift models of the knee are
discussed based on this data.Comment: 8 pages, 7 figures, to appear in Nuclear Physics B, Proceedings
Supplements, as part of the volume for the CRIS 2004, Cosmic Ray
International Seminar: GZK and Surrounding
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