Temperature dependence of Raman vibrational bandwidths in poly(rA) and rAMP

Isotropic and anisotropic spontaneous Raman spectra were obtained from solutions of poly(ra) and rAMP in buffer. The temperature dependence of these spectra was measured to elucidate the influence of macromolecular dynamics and solvent dynamics on the bandwidths of base vibrations in the single stranded polynucleotide poly(rA). The temperature dependence of a bandwidth depends upon the particular vibration under study. The bands can for the larger part be described by Lorentz functions. When fitted by Voigt functions, maximally 10% of each bandprofile of the adenine base vibrations can be attributed to a Gaussian component. The second moment has been determined from the spectra for the 725 cm¿1 band. From the second moment and the bandwidth, we were able to deduce that the vibrational oscillator is in the fast modulation limit. The determined timescale (perturbation correlation time 0.13 ps) eliminate perturbations connected to long range diffusion like concentration fluctuations (timescale in the order of 10 ps). The spectra were analyzed by an extensive curve fitting procedure providing accurate bandparameters (position, width and integrated intensity). The 725 cm¿1 band of adenine has a bandwidth which is dependent upon the degree of polymerization. In RAMP it is 17.6 cm¿1, in stacked (i.e. low temperature 5°C) poly(rA) it is 11.5 cm¿1. The bandwidth of the adenine vibration at 1336 cm¿1 cm¿1 has a temperature dependence which is similar to the intensity changes of the Raman and the absorption hypochromic effect as a function of temperature. The melting transition can therefore be followed by the changes in bandwidth of suitable vibrations

Subpicosecond Dynamics in Nucleotides Measured by Spontaneous Raman Spectroscopy

The band widths in Raman spectra are sensitive to dynamics active on a time scale from 0.1 to 10 ps. The band widths of nucleotide vibrations and their dependence on temperature, concentration, and structure are reported. From the experimental band widths and second moments, it is derived that the adenine vibrations at 725, 1336, 1480, and 1575 cm-1, and the uracil vibration at 787 cm-1, are in the fast modulation limit. The correlation times of the perturbations are faster than 0.4 ps. Thermal melting of the helical structure in polynucleotides results in larger band widths, due to an increase in vibrational dephasing and energy relaxation as a consequence of the increased interaction of the base moieties with the solvent molecules. The band width of the 725 cm-1 adenine vibration is dependent on the type and structure of the backbone. It is found to be perturbed by movements of the sugar-phosphate moiety relative to the base. The band width of the 1575 cm-1 adenine vibration is found to be sensitive to the base-pairing interaction. From a comparison of the band widths in polynucleotides with a different base sequence (homopolymer vs alternating purine-pyrimidine sequence), it is concluded that resonant vibrational energy transfer between the base molecules is not important as a relaxation process for the vibrational band widths of nucleotides. Several theoretical models for the interpretation of band widths are discussed. The theory does not take into account the strong hydrogen-bonding nature water and hence fails to describe the observations in nucleotide-water systems. The bands of the carbonyl stretching vibrations are inhomogeneously broadened. The carbonyl groups have a strong dipolar interaction with the polar water molecules and are therefore strongly perturbed by coupling to the heatbath via hydrogen bonds

Temperature dependence of Raman vibrational bandwidths in poly(rA) and rAMP

Isotropic and anisotropic spontaneous Raman spectra were obtained from solutions of poly(ra) and rAMP in buffer. The temperature dependence of these spectra was measured to elucidate the influence of macromolecular dynamics and solvent dynamics on the bandwidths of base vibrations in the single stranded polynucleotide poly(rA). The temperature dependence of a bandwidth depends upon the particular vibration under study. The bands can for the larger part be described by Lorentz functions. When fitted by Voigt functions, maximally 10% of each bandprofile of the adenine base vibrations can be attributed to a Gaussian component. The second moment has been determined from the spectra for the 725 cm¿1 band. From the second moment and the bandwidth, we were able to deduce that the vibrational oscillator is in the fast modulation limit. The determined timescale (perturbation correlation time 0.13 ps) eliminate perturbations connected to long range diffusion like concentration fluctuations (timescale in the order of 10 ps). The spectra were analyzed by an extensive curve fitting procedure providing accurate bandparameters (position, width and integrated intensity). The 725 cm¿1 band of adenine has a bandwidth which is dependent upon the degree of polymerization. In RAMP it is 17.6 cm¿1, in stacked (i.e. low temperature 5°C) poly(rA) it is 11.5 cm¿1. The bandwidth of the adenine vibration at 1336 cm¿1 cm¿1 has a temperature dependence which is similar to the intensity changes of the Raman and the absorption hypochromic effect as a function of temperature. The melting transition can therefore be followed by the changes in bandwidth of suitable vibrations

Sport policy convergence: a framework for analysis

This is an Accepted Manuscript of an article published by Taylor & Francis Group in European Sport Management Quarterly on 30th April 2012, available online at: http://www.tandfonline.com/10.1080/16184742.2012.669390The growth in the comparative analysis of sport management processes and policy has led to an increased interest in the concept of convergence. However, the concept is too often treated as unproblematic in definition, measurement and operationalisation. It is argued in this paper that a more effective framework for examining claims of convergence is one that analyses the concept in terms of seven dimensions which can be explored through a mix of quantitative and qualitative methods of data collection. It is also argued that a deeper understanding of the process of convergence can be gained by operationalising the concept in the context of a selected range of meso-level theories of the policy process or of specific aspects of the process. The proposed analytic framework provides not only a definition of convergence but also the basis for a more nuanced investigation of hypotheses of convergence

ExploreASL: an image processing pipeline for multi-center ASL perfusion MRI studies

Arterial spin labeling (ASL) has undergone significant development since its inception, with a focus on improving standardization and reproducibility of its acquisition and quantification. In a community-wide effort towards robust and reproducible clinical ASL image processing, we developed the software package ExploreASL, allowing standardized analyses across centers and scanners. The procedures used in ExploreASL capitalize on published image processing advancements and address the challenges of multi-center datasets with scanner-specific processing and artifact reduction to limit patient exclusion. ExploreASL is self-contained, written in MATLAB and based on Statistical Parameter Mapping (SPM) and runs on multiple operating systems. To facilitate collaboration and data-exchange, the toolbox follows several standards and recommendations for data structure, provenance, and best analysis practice. ExploreASL was iteratively refined and tested in the analysis of >10,000 ASL scans using different pulse-sequences in a variety of clinical populations, resulting in four processing modules: Import, Structural, ASL, and Population that perform tasks, respectively, for data curation, structural and ASL image processing and quality control, and finally preparing the results for statistical analyses on both single-subject and group level. We illustrate ExploreASL processing results from three cohorts: perinatally HIV-infected children, healthy adults, and elderly at risk for neurodegenerative disease. We show the reproducibility for each cohort when processed at different centers with different operating systems and MATLAB versions, and its effects on the quantification of gray matter cerebral blood flow. ExploreASL facilitates the standardization of image processing and quality control, allowing the pooling of cohorts which may increase statistical power and discover between-group perfusion differences. Ultimately, this workflow may advance ASL for wider adoption in clinical studies, trials, and practice

Potentially hazardous substances in surface waters

In this paper, some initial results of a monitoring program with respect to toxic substances in the river Rhine are presented together with experimental details on the analytical methods used. The results cover the period, September 1969–March 1972. α-Benzenehexachloride (α-BHC), γ-BHC or lindane, and hexachlorobenzene (HCB) are nearly always present in the Rhine. The concentration of these substances in the river is about ten times as high as in typically “agricultural” surface waters. Endosulfan, an insecticide which had been found in the river Rhine in several “waves” during the years 1969 and 1970, has been rarely found in that river since July, 1970. The other organochlorine pesticides and their metabolites (heptachlor, -epoxide, aldrin, dieldrin, endrin and DDT-complex) have occasionally been found, but only in low concentrations. Polychlorinated biphenyls (PCB's) have not yet been found in detectable amounts, i.e. <0.5 μg/liter. Cholinesterase inhibitors are always present in the Rhine, and their occurrence is typical for the Rhine and its tributaries

Blootstelling van mens en milieu aan HCB in Nederland

HCB is in goed detecteerbare concentraties gevonden in oppervlaktewater, sedimenten, vis, produkten van dierlijke oorsprong, veevoeders, menselijke weefsels, moedermelk en sommige formuleringen van bestrijdingsmiddelen. In mindere mate kunnen gewassen, geteelt op met HCB verontreinigde gronden, ook HCB bevatten. De gemiddelde dagelijkse opname van HCB bedroeg in 1976/78, zoals geschat uit een totaal-dieetonderzoek, 1 mu-g/persoon (maximum waarde: 12 mu- g/persoon). Een groot aantal maatregelen is sinds het begin van de jaren zeventig genomen om de blootstelling van mens en milieu aan HCB zo ver mogelijk te verlagen. Tengevolge hiervan zijn sindsdien aanzienlijke afnames van concentraties in alle compartimenten bereikt.Abstract not availableRIV

Organochloorverbindingen en PCB&apos;s in humane weefsels van de Nederlandse bevolking (1968-1983)

In dit rapport zijn de onderzoekingen samengevat die sinds 1968 door het RIV(M) zijn uitgevoerd in opdracht van de HIL en/of GHI m.b.t. het voorkomen van de organochloorverbindingen hexachloorbenzeen (HCB), HCH-isomeren, heptachloorepoxide, dieldrin, DDT-complex en PCB's in humane weefsels. Voor een aantal van de genoemde stoffen, met name HCB, beta-HCH en p.p'-DDT, is een opvallende daling in gehalte over de laatste tien jaar gevonden. Voor geen van genoemde stoffen is een toename in gehalte gevonden.Abstract not availableHILGH

Residues of polychlorinated biphenyls (PCBs) in animal feed and technical fats (XXIII)

In 74 monsters mengvoeder en 4 monsters "technisch vet" werd het PCB- gehalte bepaald. De gemiddelde gehalten bedragen (in mg/kg op produktbasis, bepaald na perchloreren en uitgedrukt als Clophen A60) voor varkensmestvoeder 0,12, voor rundveevoeder 0,16, voor legvoeder 0,18 en voor slachtkuikenvoeder 0,25. Er bestaat een positieve correlatie tussen vetgehalte van het mengvoeder en het PCB-gehalte. De onderzochte monsters "technisch vet" bevatten 0,88-1,23 mg/kg PCB's (bepaald en uitgedrukt als boven) en vormen dus een reele potentiele bron van verontreiniging voor mengvoeders. Voor normstelling wordt bepaling van enige belangrijke "gids-componenten" van de PCB's aanbevolen.Abstract not availableVH

The determination of synthetic pyrethroids in meat

Een methode voor de bepaling van residuen van vijf belangrijke synthetische pyrethroiden (permethrin, cypermethrin, flucythrinaat, fenvaleraat en deltamethrin) in vlees werd ontwikkeld ten behoeve van een door de Hoofdinspectie van de Volksgezondheid, belast met het toezicht op levensmiddelen en de keuring van waren (HIL) geplande "gecoordineerde actie" voor de bepaling van diverse bestrijdingsmiddelen in vlees. De detectiegrens van de methode bedraagt ca. 0,02 mg/kg per pyrethroide, de opbrengst 84-103% bij een toevoegingsniveau van 0,06-6,4 mg/kg.Abstract not availableHI