3,357 research outputs found
Can we detect Hot or Cold spots in the CMB with Minkowski Functionals?
In this paper, we investigate the utility of Minkowski Functionals as a probe
of cold/hot disk-like structures in the CMB. In order to construct an accurate
estimator, we resolve a long-standing issue with the use of Minkowski
Functionals as probes of the CMB sky -- namely that of systematic differences
("residuals") when numerical and analytical MF are compared. We show that such
residuals are in fact by-products of binning, and not caused by pixelation or
masking as originally thought. We then derive a map-independent estimator that
encodes the effects of binning, applicable to beyond our present work. Using
this residual-free estimator, we show that small disk-like effects (as claimed
by Vielva et al.) can be detected only when a large sample of such maps are
averaged over. In other words, our estimator is noise-dominated for small disk
sizes at WMAP resolution. To confirm our suspicion, we apply our estimator to
the WMAP7 data to obtain a null result.Comment: 15 pages, 13 figure
Endothelium-independent vasodilatory effect of Sailuotong (SLT) on rat isolated tail artery
Background. Sailuotong (SLT) is a standardized three-herb formulation consisting of extracts of Panax ginseng, Ginkgo biloba, and Crocus sativus for the treatment of vascular dementia (VaD). Although SLT has been shown to increase cerebral blood flow, the direct effects of SLT on vascular reactivity have not been explored. (is study aims to examine the vasodilatory effects of SLT and the underlying mechanisms in rat isolated tail artery. Methods. Male (250â300 g) Wistar Kyoto (WKY) rat tail artery was isolated for isometric tension measurement. (e effects of SLT on the influx of calcium through the cell membrane calcium channels were determined in Ca2+-free solution experiments. Results. SLT (0.1â5,000 ÎŒg/ml) caused a concentration-dependent relaxation in rat isolated tail artery precontracted by phenylephrine. In the contraction experiments, SLT (500, 1,000, and 5,000 ÎŒg/mL) significantly inhibited phenylephrine (0.001 to 10 ÎŒM)- and KCl (10â80 mM)-induced contraction, in a concentration-dependent manner. In Ca2+-free solution, SLT (500, 1,000, and 5,000 ÎŒg/mL) markedly suppressed Ca2+-induced (0.001â3 mM) vasoconstriction in a concentration-dependent manner in both phenylephrine (10 ÎŒM) or KCl (80 mM) stimulated tail arteries. L-type calcium channel blocker nifedipine (10 ÎŒM) inhibited PE-induced contraction. Furthermore, SLT significantly reduced phenylephrine-induced transient vasoconstriction in the rat isolated tail artery. Conclusion. SLT induces relaxation of rat isolated tail artery through endothelium-independent mechanisms. (e SLT-induced vasodilatation appeared to be jointly meditated by blockages of extracellular Ca2+ influx via receptor-gated and voltage-gated Ca2+ channels and inhibition of the release of Ca2+ from the sarcoplasmic reticulum
A Search for HI in E+A Galaxies
We present the results of HI line and radio continuum observations of five
nearby E+A galaxies. These galaxies have spectra that are dominated by a young
stellar component but lack the emission lines characteristic of significant,
on-going star formation. They are selected from a unique sample of 21 E+A's
identified by Zabludoff et al.(1996) in their spectroscopic search for E+A
galaxies using the Las Campanas Redshift Survey, where over 11,000 nearby
galaxies were examined. The five E+A galaxies span a range of environments:
three are in the field and two are in clusters. Only one system was detected in
HI emission, the field E+A galaxy EA1, with a total flux of 0.30 +/- 0.02 Jy
km/s and an HI mass of (3.5 +/- 0.2) 10^9 h^(-2) M_sun. The HI morphology and
kinematics of EA 1 suggest a galaxy-galaxy interaction, with a dynamical age of
about 6 x 10^8 h^(-1) yr inferred from the HI tail lengths and velocities. This
age estimate is consistent with the interpretation drawn from optical
spectroscopy that starbursts in E+A galaxies began (and subsequently ended)
within the last 10^9 yr. Our HI detection limits are such that if the other
E+A's in our sample had the HI properties of EA 1, we would have detected (or
marginally detected) them. We conclude that E+A galaxies have a range of HI
properties. None of the galaxies were detected in radio continuum emission,
with upper limits to the radio power of about 10^21 h^(-2) W/Hz. Our limits
exclude the possibility that these E+A's are dust-enshrouded massive starburst
galaxies, but are insufficient to exclude modest star formation rates of less
than a few h^(-2) M_sun per yr.Comment: 21 Latex pages, including 5 figures and 6 tables. Uses Aastex. To
appear in AJ, April 2001; minor changes to text and Figure
Applications of Direct Injection Soft Chemical Ionisation-Mass Spectrometry for the Detection of Pre-blast Smokeless Powder Organic Additives
Analysis of smokeless powders is of interest from forensics and security perspectives. This article reports the detection of smokeless powder organic additives (in their pre-detonation condition), namely the stabiliser diphenylamine and its derivatives 2-nitrodiphenylamine and 4-nitrodiphenylamine, and the additives (used both as stabilisers and plasticisers) methyl centralite and ethyl centralite, by means of swab sampling followed by thermal desorption and direct injection soft chemical ionisation-mass spectrometry. Investigations on the product ions resulting from the reactions of the reagent ions H3O+ and O2+ with additives as a function of reduced electric field are reported. The method was comprehensively evaluated in terms of linearity, sensitivity and precision. For H3O+, the limits of detection (LoD) are in the range of 41-88 pg of additive, for which the accuracy varied between 1.5 and 3.2%, precision varied between 3.7 and 7.3% and linearity showed R20.9991. For O2+, LoD are in the range of 72 to 1.4 ng, with an accuracy of between 2.8 and 4.9% and a precision between 4.5 and 8.6% and R20.9914. The validated methodology was applied to the analysis of commercial pre-blast gun powders from different manufacturers.(VLID)4826148Accepted versio
Human hippocampal neurogenesis drops sharply in children to undetectable levels in adults.
New neurons continue to be generated in the subgranular zone of the dentate gyrus of the adult mammalian hippocampus. This process has been linked to learning and memory, stress and exercise, and is thought to be altered in neurological disease. In humans, some studies have suggested that hundreds of new neurons are added to the adult dentate gyrus every day, whereas other studies find many fewer putative new neurons. Despite these discrepancies, it is generally believed that the adult human hippocampus continues to generate new neurons. Here we show that a defined population of progenitor cells does not coalesce in the subgranular zone during human fetal or postnatal development. We also find that the number of proliferating progenitors and young neurons in the dentate gyrus declines sharply during the first year of life and only a few isolated young neurons are observed by 7 and 13 years of age. In adult patients with epilepsy and healthy adults (18-77 years; nâ=â17 post-mortem samples from controls; nâ=â12 surgical resection samples from patients with epilepsy), young neurons were not detected in the dentate gyrus. In the monkey (Macaca mulatta) hippocampus, proliferation of neurons in the subgranular zone was found in early postnatal life, but this diminished during juvenile development as neurogenesis decreased. We conclude that recruitment of young neurons to the primate hippocampus decreases rapidly during the first years of life, and that neurogenesis in the dentate gyrus does not continue, or is extremely rare, in adult humans. The early decline in hippocampal neurogenesis raises questions about how the function of the dentate gyrus differs between humans and other species in which adult hippocampal neurogenesis is preserved
Delays in Leniency Application: Is There Really a Race to the Enforcer's Door?
This paper studies cartelsâ strategic behavior in delaying leniency applications, a take-up decision that has been ignored in the previous literature. Using European Commission decisions issued over a 16-year span, we show, contrary to common beliefs and the existing literature, that conspirators
often apply for leniency long after a cartel collapses. We estimate hazard and probit models to study the determinants of leniency-application delays. Statistical tests find that delays are symmetrically affected by antitrust policies and macroeconomic fluctuations. Our results shed light on the design of
enforcement programs against cartels and other forms of conspiracy
Rational Design of Pathogen-Mimicking Amphiphilic Materials as Nanoadjuvants
An opportunity exists today for cross-cutting research utilizing advances in materials science, immunology, microbial pathogenesis, and computational analysis to effectively design the next generation of adjuvants and vaccines. This study integrates these advances into a bottom-up approach for the molecular design of nanoadjuvants capable of mimicking the immune response induced by a natural infection but without the toxic side effects. Biodegradable amphiphilic polyanhydrides possess the unique ability to mimic pathogens and pathogen associated molecular patterns with respect to persisting within and activating immune cells, respectively. The molecular properties responsible for the pathogen-mimicking abilities of these materials have been identified. The value of using polyanhydride nanovaccines was demonstrated by the induction of long-lived protection against a lethal challenge of Yersinia pestis following a single administration ten months earlier. This approach has the tantalizing potential to catalyze the development of next generation vaccines against diseases caused by emerging and re-emerging pathogens
Generation Gap and the Impact of the Web on Goods Quality Perceptions
This study explores how age and general online shopping experience affect consumer perceptions on product quality uncertainty. Using the survey data collected from 549 consumers, we investigated how they perceive the uncertainty of product quality on six search, experience and credence goods. The ANOVA results show that age and the Web shopping experience of consumers are significant factors. A generation gap is indeed seen for all but one experience good. Web shopping experience is not a significant factor for search goods but is for experience and credence goods. There is an interaction effect between age and Web shopping experience for one credence good. Implications of these results are discussed
Measurements of the Sensitivity of Aerosol Hygroscopicity and the kappa Parameter to the O/C Ratio
Compiler Controlled Speculation for Power Aware ILP Extraction in Dataflow Architectures
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