On Non Perturbative Corrections to the Potential for Heavy Quarks

We discuss non perturbative corrections to the Coulomb-like potential of heavy quarks at short distances. We consider both the standard framework provided by infrared renormalons and the assumption that confinement does not allow weak fields to penetrate the vacuum. In the former case the leading correction at short distances turns out to be quadratic in r for static quarks. In the latter case we find a potential which is proportional to r as r rightarrow 0. We point out that similar effects arise due to a new kind of non perturbative correction proportional to 1/Q^2, which is unaccounted for by the operator product expansion and which was recently discussed within a different framework. Phenomenological implications of the linear correction to the potential are briefly reviewed.Comment: 13 pages, latex, 2 figures, uses eps

Noisy Wavefront Propagation in the Fisher‐Kolmogorov‐Petrovsky‐Piscounov Equation

We discuss some conjectures and open questions regarding the velocity of front propagation in the stochastic Fisher‐Kolmogorov‐Petrovsky‐Piscunov equation. © 2003 American Institute of PhysicsPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87303/2/523_1.pd

Sub-millimeter wave frequency heterodyne detector system

The present invention relates to sub-millimeter wave frequency heterodyne imaging systems. More specifically, the present invention relates to a sub-millimeter wave frequency heterodyne detector system for imaging the magnitude and phase of transmitted power through or reflected power off of mechanically scanned samples at sub-millimeter wave frequencies

Bioactive secondary metabolites from the endophytic fungus Chaetomium sp. isolated from Salvia officinalis growing in Morocco

This study reports the chemical investigation and cytotoxic activity of the secondary metabolites produced by the endophytic fungus Chaetomium sp. isolated from Salvia officinalis growing in Morocco. This plant was collected from the Beni-Mellal Mountain in Morocco and belongs to the Lamiaceae family and is named in Morocco 'Salmia'. The endophytic fungus Chaetomium sp. was isolated from the tissues of the stem of this plant. The fungal strain was identified by PCR. The crude organic extract of the fungal strain was proven to be active when tested for cytotoxicity against L5178Y mouse lymphoma cells. Chemical investigation of the secondary metabolites showed that cochliodinol is the main component beside isocochliodinol. The structures of the isolated compounds were determined on the basis of NMR analysis (1H, 13C, COSY and HMBC) as well as by mass spectrometry using ESI (Electron Spray Ionisation) as source

Crystal structure of [4-(2-methoxyphenyl)-3-methyl-1-phenyl-6-trifluoromethyl-1H-pyrazolo[3,4-b]pyridin-5-yl](thiophen-2-yl)methanone

The title compound, C[subscript 26]H[subscript 18]F[subscript 3]N[subscript 3]O[subscript 2]S, a 2-meth­oxy-substituted derivative, is closely related to its 4-methyl- and 4-chloro-substituted analogues and yet displays no structural relationships with them. The thio­phene ring is disorder free and the -CF[subscript 3] group exhibits disorder, respectively, in contrast and similar to that observed in the 4-methyl- and 4-chloro-substituted derivatives. The torsion angle which defines the twist of the thio­phene ring is -69.6 (2)° (gauche) in the title compound, whereas it is anti­clinal in the 4-methyl- and 4-chloro-substituted derivatives, with respective values of 99.9 (2) and 99.3 (2)°. The absence of disorder in the thio­phene ring facilitates one of its ring C atoms to participate in the lone inter­molecular C-H...O hydrogen bond present in the crystal, leading to a characteristic C(5) chain graph-set motif linking mol­ecules related through glides along [010]. An intra­moleculr C-H...N hydrogen bond also occurs

Brewster-angle measurements of sea-surface reflectance using a high resolution spectroradiometer

This paper describes the design, construction and testing of a ship-borne spectroradiometer based on an imaging spectrograph and cooled CCD array with a wavelength range of 350-800 nm and 4 nm spectral sampling. The instrument had a minimum spectral acquisition time of 0.1 s, but in practice data were collected over periods of 10 s to allow averaging of wave effects. It was mounted on a ship's superstructure so that it viewed the sea surface from a height of several metres at the Brewster angle (53 degrees) through a linear polarizing filter. Comparison of sea-leaving spectra acquired with the polarizer oriented horizontally and vertically enabled estimation of the spectral composition of sky light reflected directly from the sea surface. A semi-empirical correction procedure was devised for retrieving water-leaving radiance spectra from these measurements while minimizing the influence of reflected sky light. Sea trials indicated that reflectance spectra obtained by this method were consistent with the results of radiance transfer modelling of case 2 waters with similar concentrations of chlorophyll and coloured dissolved organic matter. Surface reflectance signatures measured at three locations containing blooms of different phytoplankton species were easily discriminated and the instrument was sufficiently sensitive to detect solar-stimulated fluorescence from surface chlorophyll concentrations down to 1 mg m−3

A new high-throughput method for simultaneous detection of drug resistance associated mutations in Plasmodium vivax dhfr, dhps and mdr1 genes

<p>Abstract</p> <p>Background</p> <p>Reports of severe cases and increasing levels of drug resistance highlight the importance of improved <it>Plasmodium vivax </it>case management. Whereas monitoring <it>P. vivax </it>resistance to anti-malarial drug by <it>in vivo </it>and <it>in vitro </it>tests remain challenging, molecular markers of resistance represent a valuable tool for high-scale analysis and surveillance studies. A new high-throughput assay for detecting the most relevant markers related to <it>P. vivax </it>drug resistance was developed and assessed on Papua New Guinea (PNG) patient isolates.</p> <p>Methods</p> <p><it>Pvdhfr, pvdhps </it>and <it>pvmdr1 </it>fragments were amplified by multiplex nested PCR. Then, PCR products were processed through an LDR-FMA (ligase detection reaction - fluorescent microsphere assay). 23 SNPs, including <it>pvdhfr </it>57-58-61 and 173, <it>pvdhps </it>382-383, 553, 647 and <it>pvmdr1 </it>976, were simultaneously screened in 366 PNG <it>P. vivax </it>samples.</p> <p>Results</p> <p>Genotyping was successful in 95.4% of the samples for at least one gene. The coexistence of multiple distinct haplotypes in the parasite population necessitated the introduction of a computer-assisted approach to data analysis. Whereas 73.1% of patients were infected with at least one wild-type genotype at codons 57, 58 and 61 of <it>pvdhfr</it>, a triple mutant genotype was detected in 65.6% of the patients, often associated with the 117T mutation. Only one patient carried the 173L mutation. The mutant 647P <it>pvdhps </it>genotype allele was approaching genetic fixation (99.3%), whereas 35.1% of patients were infected with parasites carrying the <it>pvmdr1 </it>976F mutant allele.</p> <p>Conclusions</p> <p>The LDR-FMA described here allows a discriminant genotyping of resistance alleles in the <it>pvdhfr</it>, <it>pvdhps</it>, and <it>pvmdr1 </it>genes and can be used in large-scale surveillance studies.</p