267 research outputs found
Investigations in the control of the tobacco leaf-miner, Gnorimoschema operculella Zell. (Lepitoptera: Gelechiidae), with D.D.T. and "Gammexane"
Experiments in the control of the tobacco leaf-miner, Gnorimoschema operculella Zell., with D.D.T. and "Gammexane" were conducted at Mereeba in northern Queensland. Effective control was obtained with 0.1 per cent D.D.T. sprays and 1.0 and 2.0 per cent D.D.T. dusts applied immediately after transplanting, followed by regular fortnightly treatments up to a maximum of five applications in all. A total of three applications made at fortnightly intervals also afforded a high degree of protection to the crop. "Gammexane" at the high concentration was inferior to D.D.T. even at the low concentration of the latter; in addition, the sprays and dusts containing it had such a pronounced phytocidal effect on the tobacco plants that their use had to be discontinued before the termination of the experiment
The role of type 4 phosphodiesterases in generating microdomains of cAMP: Large scale stochastic simulations
Cyclic AMP (cAMP) and its main effector Protein Kinase A (PKA) are critical for several aspects of neuronal function including synaptic plasticity. Specificity of synaptic plasticity requires that cAMP activates PKA in a highly localized manner despite the speed with which cAMP diffuses. Two mechanisms have been proposed to produce localized elevations in cAMP, known as microdomains: impeded diffusion, and high phosphodiesterase (PDE) activity. This paper investigates the mechanism of localized cAMP signaling using a computational model of the biochemical network in the HEK293 cell, which is a subset of pathways involved in PKA-dependent synaptic plasticity. This biochemical network includes cAMP production, PKA activation, and cAMP degradation by PDE activity. The model is implemented in NeuroRD: novel, computationally efficient, stochastic reaction-diffusion software, and is constrained by intracellular cAMP dynamics that were determined experimentally by real-time imaging using an Epac-based FRET sensor (H30). The model reproduces the high concentration cAMP microdomain in the submembrane region, distinct from the lower concentration of cAMP in the cytosol. Simulations further demonstrate that generation of the cAMP microdomain requires a pool of PDE4D anchored in the cytosol and also requires PKA-mediated phosphorylation of PDE4D which increases its activity. The microdomain does not require impeded diffusion of cAMP, confirming that barriers are not required for microdomains. The simulations reported here further demonstrate the utility of the new stochastic reaction-diffusion algorithm for exploring signaling pathways in spatially complex structures such as neurons
An infinite genus mapping class group and stable cohomology
We exhibit a finitely generated group \M whose rational homology is
isomorphic to the rational stable homology of the mapping class group. It is
defined as a mapping class group associated to a surface \su of infinite
genus, and contains all the pure mapping class groups of compact surfaces of
genus with boundary components, for any and . We
construct a representation of \M into the restricted symplectic group of the real Hilbert space generated by the homology
classes of non-separating circles on \su, which generalizes the classical
symplectic representation of the mapping class groups. Moreover, we show that
the first universal Chern class in H^2(\M,\Z) is the pull-back of the
Pressley-Segal class on the restricted linear group
via the inclusion .Comment: 14p., 8 figures, to appear in Commun.Math.Phy
Growth Differentiation Factor 15 at 1Â Month After an Acute Coronary Syndrome Is Associated With Increased Risk of Major Bleeding.
BACKGROUND: Growth differentiation factor-15 (GDF-15) is related to major bleeding when measured at initial presentation in patients with acute coronary syndromes (ACSs) treated with dual antiplatelet therapy. It is unknown whether follow-up measurements provide additional information. The objective of this study was to investigate whether GDF-15 measured 1Â month after an ACS provides additional information beyond the baseline levels with regard to the risk of major bleeding. METHODS AND RESULTS: GDF-15 was measured at baseline and at 1Â month after an ACS in 4049 patients included in the PLATelet inhibition and patient Outcomes (PLATO) trial. The association between 1-month GDF-15 level and non-coronary artery bypass grafting surgery-related major bleeding was assessed by a multivariable Cox model, adjusting for baseline GDF-15, age, anemia, impaired renal function, history of gastrointestinal bleeding, and sex. Elevated GDF-15 (>1800Â ng/L) at 1Â month was associated with an increased risk of non-coronary artery bypass grafting-related major bleeding (3.9% versus 1.2%; hazard ratio, 3.38; 95% CI, 1.89-6.06), independent of baseline GDF-15. Patients who had elevated GDF-15 levels at baseline and subsequent nonelevated GDF-15 at 1Â month had a similar risk as patients who had nonelevated levels at both measurements. CONCLUSIONS: GDF-15 at 1Â month after an ACS is related to the risk of bleeding during DAPT and provides additional information on the bleeding risk beyond baseline GDF-15 levels. GDF-15 levels may therefore be useful as part of decision support concerning long-term antithrombotic treatment in patients post-ACS. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00391872
Infra-red spectra of 1:10-phenanthroline metal complexes in the rock salt region below 2000 cm-1
Infra-red spectra of twenty two metal-1:10-phenanthroline perchlorates together with spectra of the free ligand, its hydrate and perchlorate salt have been obtained in the region between 600 and 2000 cm-1 from Nujol mulls. In general, the spectra of the complexes were remarkably similar in their gross features and no obvious correlations with magnetic or other physical properties were noted. However, the results provide evidence for co-ordination in the case of the alkali metal complexes and also indicate a co-ordination number of eight in the alkaline earth, lead and manganese complexes. The compositions of all compounds studied were confirmed by elementary microanalysis and the list includes several new compounds as well as a few having compositions differing slightly from those previously reported. The interpretation of the principal features of the spectra is discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32463/1/0000547.pd
Review of the Diagnosis and Treatment of Periodic Paralysis
Periodic paralyses (PPs) are rare neuromuscular disorders caused by mutations in skeletal muscle sodium, calcium, and potassium channel genes. PPs include hypokalemic paralysis, hyperkalemic paralysis, and Andersen-Tawil syndrome. Common features of PP include autosomal dominant inheritance, onset typically in the first or second decades, episodic attacks of flaccid weakness, which are often triggered by diet or rest after exercise.
Diagnosis is based on the characteristic clinic presentation then confirmed by genetic testing. In the absence of an identified genetic mutation, documented low or high potassium levels during attacks or a decrement on long exercise testing support diagnosis.
The treatment approach should include both management of acute attacks and prevention of attacks. Treatments include behavioral interventions directed at avoidance of triggers, modification of potassium levels, diuretics, and carbonic anhydrase inhibitors
The Refederalization of American Health Care
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69090/2/10.1177_107755878704400103.pd
Interleukinâ18 in patients with acute coronary syndromes
Background
We aimed to assess associations between circulating ILâ18 concentrations and cardiovascular outcomes in patients with acute coronary syndromes (ACS).
Hypothesis and Methods
Plasma ILâ18 concentrations were measured at admission, discharge, 1 month, and 6 months in patients with ACS in the PLATelet inhibition and patient Outcomes (PLATO) trial. Associations with outcomes were evaluated with Cox regression models on the composite of CV death, spontaneous myocardial infarction (sMI), or stroke; and on CV death or sMI separately, including adjustment for clinical risk factors and biomarkers (cTnTâhs, NTâproBNP, cystatin C, CRPâhs, and GDFâ15).
Results
Median ILâ18 concentrations at baseline, discharge, 1 month, and 6 months were 237, 283, 305, and 320âng/L (n = 16â636). Male sex, obesity, diabetes, and plasma levels of cystatin C, GDFâ15, and CRPâhs were independently associated with higher ILâ18 levels. Higher baseline ILâ18 levels were associated with the composite endpoint and with CV death (hazard ratio [HR] 1.05, 95% confidence interval [95% CI] 1.02â1.07 and HR 1.10, 95% CI 1.06â1.14, respectively, per 25% increase of ILâ18 levels). Associations remained significant after adjustment for clinical variables but became nonâsignificant after adjustment for all biomarkers (HR 1.01, 95% CI 0.98â1.04 and HR 1.04, 95% CI 1.00â1.08, respectively). There were no associations with sMI.
Conclusions
In ACS patients, ILâ18 concentrations increased after the acute event and remained increased for 6 months. Baseline ILâ18 levels were significantly associated with CV mortality, independent of clinical characteristics and indicators of renal/cardiac dysfunction but this association was attenuated after adjustment for multiple biomarkers
Horizontal Branch Stars: The Interplay between Observations and Theory, and Insights into the Formation of the Galaxy
We review HB stars in a broad astrophysical context, including both variable
and non-variable stars. A reassessment of the Oosterhoff dichotomy is
presented, which provides unprecedented detail regarding its origin and
systematics. We show that the Oosterhoff dichotomy and the distribution of
globular clusters (GCs) in the HB morphology-metallicity plane both exclude,
with high statistical significance, the possibility that the Galactic halo may
have formed from the accretion of dwarf galaxies resembling present-day Milky
Way satellites such as Fornax, Sagittarius, and the LMC. A rediscussion of the
second-parameter problem is presented. A technique is proposed to estimate the
HB types of extragalactic GCs on the basis of integrated far-UV photometry. The
relationship between the absolute V magnitude of the HB at the RR Lyrae level
and metallicity, as obtained on the basis of trigonometric parallax
measurements for the star RR Lyrae, is also revisited, giving a distance
modulus to the LMC of (m-M)_0 = 18.44+/-0.11. RR Lyrae period change rates are
studied. Finally, the conductive opacities used in evolutionary calculations of
low-mass stars are investigated. [ABRIDGED]Comment: 56 pages, 22 figures. Invited review, to appear in Astrophysics and
Space Scienc
Young and Intermediate-age Distance Indicators
Distance measurements beyond geometrical and semi-geometrical methods, rely
mainly on standard candles. As the name suggests, these objects have known
luminosities by virtue of their intrinsic proprieties and play a major role in
our understanding of modern cosmology. The main caveats associated with
standard candles are their absolute calibration, contamination of the sample
from other sources and systematic uncertainties. The absolute calibration
mainly depends on their chemical composition and age. To understand the impact
of these effects on the distance scale, it is essential to develop methods
based on different sample of standard candles. Here we review the fundamental
properties of young and intermediate-age distance indicators such as Cepheids,
Mira variables and Red Clump stars and the recent developments in their
application as distance indicators.Comment: Review article, 63 pages (28 figures), Accepted for publication in
Space Science Reviews (Chapter 3 of a special collection resulting from the
May 2016 ISSI-BJ workshop on Astronomical Distance Determination in the Space
Age
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