350 research outputs found

    fMRI protocol optimization for simultaneously studying small subcortical and cortical areas at 7 ​T

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    Most fundamental cognitive processes rely on brain networks that include both cortical and subcortical structures. Studying such networks using functional magnetic resonance imaging (fMRI) requires a data acquisition protocol that provides blood-oxygenation-level dependent (BOLD) sensitivity across the entire brain. However, when using standard single echo, echo planar imaging protocols, researchers face a tradeoff between BOLD-sensitivity in cortex and in subcortical areas. Multi echo protocols avoid this tradeoff and can be used to optimize BOLD-sensitivity across the entire brain, at the cost of an increased repetition time. Here, we empirically compare the BOLD-sensitivity of a single echo protocol to a multi echo protocol. Both protocols were designed to meet the specific requirements for studying small, iron rich subcortical structures (including a relatively high spatial resolution and short echo times), while retaining coverage and BOLD-sensitivity in cortical areas. The results indicate that both sequences lead to similar BOLD-sensitivity across the brain at 7 ​T

    Responses of substantia gelatinosa neurons to putative neurotransmitters in an in vitro preparation of the adult rat spinal cord

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    Extracellular recordings were performed from neurons of the substantia gelatinosa (SG) in an in vitro preparation obtained from the spinal cord of adult rats. About 40% of neurons were spontaneously active. They could be synaptically influenced by low and high threshold fiber input entering the spinal cord through dorsal and ventral and ventral roots. Repetitive low threshold stimulation led to a transient increase in activity of a number of these neurons, whereas high intensity stimulation predominantly reduced excitability. The majority of non-spontaneously active neurons responded to an increase of stimulus intensity covariantly with an increase in firing rate. The excitatory effect of phoretically administeredl-glutamate as well as synaptically induced and spontaneous activity was reduced or abolished by phoretically administered GABA, glycine or the enkephalin-analogued-Ala2-d-Leu5-enkephalin. The actions of the enkephalin analogue were blocked by phoretically applied naloxone. The findings are consistent with the notion from in vivo investigations of a structurally and functionally heterogeneous population of neurons which display a responsiveness to microtopically applied putative neurotransmitters resembling dorsal horn neurons in deeper layers

    A rapid and reliable determination of doxycycline hyclate by HPLC with UV detection in pharmaceutical samples

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    An accurate, sensitive and reproducible high performance liquid chromatographic (HPLC) method for the quantification of doxycycline hyclate in pharmaceutical samples has been developed and validated. The drug and the standard were eluted from a Lichrosorb RP-8 (250 mm´4.6 mm, 10 mm particle size) at 20 °C with a mobile phase consisting of methanol, acetonitrile and 0.010 M aqueous solution of oxalic acid (2:3:5, v/v/v). The flow rate was 1.25 ml min-1. A UV detector set at 350 nm was used to monitor the effluent. Each analysis required no longer than 4 min. The limits of detection and quantification were 1.15 and 3.84 μg ml-1, respectively. Recoveries for different concentrations ranged from 99.58 to 101.93 %

    Exercise-Based Cardiac Rehabilitation in Twelve European Countries Results of the European Cardiac Rehabilitation Registry

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    AIM: Results from EuroCaReD study should serve as a benchmark to improve guideline adherence and treatment quality of cardiac rehabilitation (CR) in Europe. METHODS AND RESULTS: Data from 2.054 CR patients in 12 European countries were derived from 69 centres. 76% were male. Indication for CR differed between countries being predominantly ACS in Switzerland (79%), Portugal (62%) and Germany (61%), elective PCI in Greece (37%), Austria (36%) and Spain (32%), and CABG in Croatia and Russia (36%). A minority of patients presented with chronic heart failure (4%). At CR start, most patients already were under medication according to current guidelines for the treatment of CV risk factors. A wide range of CR programme designs was found (duration 3 to 24weeks; total number of sessions 30 to 196). Patient programme adherence after admission was high (85%). With reservations that eCRF follow-up data exchange remained incomplete, patient CV risk profiles experienced only small improvements. CR success as defined by an increase of exercise capacity >25W was significantly higher in young patients and those who were employed. Results differed by countries. After CR only 9% of patients were admitted to a structured post-CR programme. CONCLUSIONS: Clinical characteristics of CR patients, indications and programmes in Europe are different. Guideline adherence is poor. Thus, patient selection and CR programme designs should become more evidence-based. Routine eCRF documentation of CR results throughout European countries was not sufficient in its first application because of incomplete data exchange. Therefore better adherence of CR centres to minimal routine clinical standards is requested

    Prirodna radioaktivnost uglja i letećeg pepela u termoelektrani 'Nikola Tesla B'

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    Serbian thermal power plants (TPPs) produce Siliceous fly ash from lignite in the quantity of approximately 6 million tons per year. The Potential. Market for the use of fly ash is operational, but for the time being, only Used by cement producers. Fly ash radioactivity could be one of the major points of concern When larger use of fly ash is planned, particularly in the Serbian construction industry. Radioactivity measurements have been conducted regularly from 1980. This paper presents the results of a ten-year fly ash radioactivity measurements at the Nikola Tesla B TPP located in Obrenovac. In addition, the paper compares the natural radionuclides coal content data combusted by the Nikola Tesla B TPP boilers coming from the Kolubara Basin and ash created during coal combustion. Fly ash created in the Nikola Tesla TPPs boilers is characterised by the increased concentration of the natural radionuclides content compared to coal. This is the so-called technologically enhanced natural radioactivity (Technologically Enhanced Occurring Radioactive Material - TENORM) of industrial waste, whereas the average specific activities: Th-232 in coal amount to 25.2 Bq/kg, and in fly ash and coal 84.2 Bq/kg and U-238 38.3 Bq/kg, respectively. Following the obtained natural radionuclides content results it may be concluded that the Nikola Tesla B TPP ash may be disposed into the environment. Ash may be used also in the construction industry (civil engineering). In building construction applications, ash share as the additive to other building materials depends from its physical and chemical characteristics, as well as from the radionuclides activity: Ra-226, Th-232 and K-40. Unlike the thermal power plants regularly (once a year) testing the specific natural radionuclides activity in the combusted coal and boiler fly ash, the Electric Power Industry of Serbia has not performed large-scale investigations of the natural radionuclides content in coal within the Kolubara Mining Basin. Natural radionuclides content in fly ash is compared to the combusted coal some 3-4 times higher and may present a limitation for applying ash in the construction industry. In view of the above, and considering the construction industry interests in using the Nikola Tesla B TPP ash, regular investigations of the natural radionuclides content in ash created in the thermal power plants should be carried out, together with the Kolubara Mining Basin coal combusted by the Nikola Tesla B TPP and other PE EPS thermal power plants. The current Kolubara Mining Basin coal characteristics investigation programme should be supplemented by the natural radionuclides content of the uranium (U-238 and Ra-226) and thorium series (Th-232) and potassium 40(K-40).U termoelektranama (TE) Javnog preduzeća 'Elektroprivreda Srbije' (JP EPS) koje u kotlovima sagorevaju lignit, kao nus produkat nastaje godišnje oko 6 miliona tona letećeg pepela. Potencijalno tržište za upotrebu letećeg pepela postoji, ali ga za sada koriste isključivo cementare. Radioaktivnost letećeg pepela može da predstavlja jedan od važnih razloga protiv njegove šire upotrebe u građevinskoj industriji Srbije. Merenje radioaktivnosti u termoelektranama redovno se sprovodi od 1990. godine. U radu su prikazani rezultati dvadesetogodišnjih merenja radioaktivnosti letećeg pepela u termoelektrani Nikola Tesla B (TENT B) u Obrenovcu. Uporedno su prikazani podaci o sadržaju prirodnih radionuklida u uglju koji se sagoreva u kotlovima TENT B poreklom iz kolubarskog basena i pepelu koji nastaje prilikom sagorevanja uglja. Na osnovu dobijenih rezultata o sadržaju prirodnih radionuklida zaključuje se da se pepeo iz termoelektrane Nikola Tesla B može odlagati u životnu sredinu. Pepeo se može koristiti i u građevinarstvu, u niskogradnji. Kod primene u visokoj gradnji udeo pepela kao dodataka drugim građevinskim materijalima zavisi kako od njegovih fizičkih i hemijskih karakteristika, tako i od specifične aktivnosti 226Ra, 232Th i 40K

    A compact ultra-clean system for deploying radioactive sources inside the KamLAND detector

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    We describe a compact, ultra-clean device used to deploy radioactive sources along the vertical axis of the KamLAND liquid-scintillator neutrino detector for purposes of calibration. The device worked by paying out and reeling in precise lengths of a hanging, small-gauge wire rope (cable); an assortment of interchangeable radioactive sources could be attached to a weight at the end of the cable. All components exposed to the radiopure liquid scintillator were made of chemically compatible UHV-cleaned materials, primarily stainless steel, in order to avoid contaminating or degrading the scintillator. To prevent radon intrusion, the apparatus was enclosed in a hermetically sealed housing inside a glove box, and both volumes were regularly flushed with purified nitrogen gas. An infrared camera attached to the side of the housing permitted real-time visual monitoring of the cable's motion, and the system was controlled via a graphical user interface.Comment: Revised author affiliations, corrected typos, made minor improvements to text, and revised reference

    Production of Radioactive Isotopes through Cosmic Muon Spallation in KamLAND

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    Radioactive isotopes produced through cosmic muon spallation are a background for rare-event detection in ν\nu detectors, double-β\beta-decay experiments, and dark-matter searches. Understanding the nature of cosmogenic backgrounds is particularly important for future experiments aiming to determine the pep and CNO solar neutrino fluxes, for which the background is dominated by the spallation production of 11^{11}C. Data from the Kamioka liquid-scintillator antineutrino detector (KamLAND) provides valuable information for better understanding these backgrounds, especially in liquid scintillators, and for checking estimates from current simulations based upon MUSIC, FLUKA, and GEANT4. Using the time correlation between detected muons and neutron captures, the neutron production yield in the KamLAND liquid scintillator is measured to be (2.8±0.3)×104μ1g1cm2(2.8 \pm 0.3) \times 10^{-4} \mu^{-1} g^{-1} cm^{2}. For other isotopes, the production yield is determined from the observed time correlation related to known isotope lifetimes. We find some yields are inconsistent with extrapolations based on an accelerator muon beam experiment.Comment: 16 pages, 20 figure

    Search for extraterrestrial antineutrino sources with the KamLAND detector

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    We present the results of a search for extraterrestrial electron antineutrinos (νˉe\bar{\nu}_{e}'s) in the energy range 8.3MeV<Eνˉe<31.8MeV8.3 MeV < E_{\bar{\nu}_{e}} < 31.8 MeV using the KamLAND detector. In an exposure of 4.53 kton-year, we identify 25 candidate events. All of the candidate events can be attributed to background, most importantly neutral current atmospheric neutrino interactions, setting an upper limit on the probability of 8^{8}B solar νe\nu_{e}'s converting into νˉe\bar{\nu}_{e}'s at 5.3×1055.3 \times 10^{-5} (90% C.L.), if we assume an undistorted νˉe\bar{\nu}_{e} shape. This limit corresponds to a solar νˉe\bar{\nu}_{e} flux of 93cm2s193 cm^{-2} s^{-1} or an event rate of 1.6events(ktonyear)11.6 events (kton-year)^{-1} above the energy threshold (Eνˉe>8.3MeV)(E_{\bar{\nu}_{e}} > 8.3 MeV). The present data also allows us to set more stringent limits on the diffuse supernova neutrino flux and on the annihilation rates for light dark matter particles.Comment: 22 pages, 6 figure

    Measurement of the 8B Solar Neutrino Flux with the KamLAND Liquid Scintillator Detector

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    We report a measurement of the neutrino-electron elastic scattering rate from 8B solar neutrinos based on a 123 kton-day exposure of KamLAND. The background-subtracted electron recoil rate, above a 5.5 MeV analysis threshold is 1.49+/-0.14(stat)+/-0.17(syst) events per kton-day. Interpreted as due to a pure electron flavor flux with a 8B neutrino spectrum, this corresponds to a spectrum integrated flux of 2.77+/-0.26(stat)+/-0.32(syst) x 10^6 cm^-2s^-1. The analysis threshold is driven by 208Tl present in the liquid scintillator, and the main source of systematic uncertainty is due to background from cosmogenic 11Be. The measured rate is consistent with existing measurements and with Standard Solar Model predictions which include matter enhanced neutrino oscillation.Comment: 6 pages, 3 figure
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