3,961 research outputs found

    Internal-state thermometry by depletion spectroscopy in a cold guided beam of formaldehyde

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    We present measurements of the internal state distribution of electrostatically guided formaldehyde. Upon excitation with continuous tunable ultraviolet laser light the molecules dissociate, leading to a decrease in the molecular flux. The population of individual guided states is measured by addressing transitions originating from them. The measured populations of selected states show good agreement with theoretical calculations for different temperatures of the molecule source. The purity of the guided beam as deduced from the entropy of the guided sample using a source temperature of 150K corresponds to that of a thermal ensemble with a temperature of about 30 K

    Electrostatic extraction of cold molecules from a cryogenic reservoir

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    We present a method which delivers a continuous, high-density beam of slow and internally cold polar molecules. In our source, warm molecules are first cooled by collisions with a cryogenic helium buffer gas. Cold molecules are then extracted by means of an electrostatic quadrupole guide. For ND3_3 the source produces fluxes up to (7±47)×1010(7 \pm ^{7}_{4}) \times 10^{10} molecules/s with peak densities up to (1.0±0.61.0)×109(1.0 \pm ^{1.0}_{0.6}) \times 10^9 molecules/cm3^3. For H2_2CO the population of rovibrational states is monitored by depletion spectroscopy, resulting in single-state populations up to (82±10)(82 \pm 10)%.Comment: 4 pages, 4 figures, changes to the text, updated figures and reference

    De bijdrage van toevoeging van cacao aan tabak aan rookverslaving

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    In this report the effect of these compounds on the addiction to cigarette smoking was assessed, using currently available information in the literature on psychoactive compounds of cocoa. The investigated psychoactive cocoa compounds were theobromine, caffeine, serotonin, histamine, tryptophan, tryptamine, tyramine, phenylethylamine, octopamine and anandamide. The general conclusion is that the level of these compounds in added cocoa in cigarettes is not sufficient to increase the addiction to cigarette smoking.In dit rapport wordt de mogelijke bijdrage van cacao aan rookverslaving beschreven. Cacao wordt aan tabak toegevoegd om de smaak te verbeteren. Daarnaast bevat cacao tal van psychoactieve stoffen die mogelijk bijdragen aan rookverslaving Dit literatuuronderzoek beschrijft de blootstelling, farmacologie, farmacokinetiek, toxicologie, interacties en verslavende eigenschappen van de tien meest bekende stoffen in cacao. De onderzochte stoffen zijn theobromine, caffeine, serotonine, histamine, tryptofaan, tryptamine, tyramine, fenylethylamine, octopamine en anandamide. Deze stoffen komen ook via dranken en voedsel het lichaam binnen of worden door het lichaam zelf aangemaakt. Dit rapport laat zien dat de aan roken gerelateerde blootstelling aan de psychoactieve stoffen uit cacao gering is ten opzichte van de inname via voeding en dranken en/of de lichaamseigen productie van deze stoffen. Een systemisch effect lijkt derhalve onwaarschijnlijk ook al omdat lichaamseigen stoffen snel worden afgebroken. Daarnaast kunnen deze stoffen, omdat ze geinhaleerd worden, een direct effect op de luchtwegen hebben. Daarmee zou de opname van nicotine beinvloed kunnen worden. De nicotine opname zou bijvoorbeeld kunnen toenemen via luchtwegverwijding door theobromine en cafe6ne of kunnen afnemen door luchtwegvernauwing door histamine. Dit rapport laat zien dat de aan roken gerelateerde blootstelling aan deze stoffen waarschijnlijk te gering is voor een direct effect op de luchtwegen. Verder dient te worden opgemerkt dat de hoeveelheid tryptamine, tyramine en fenylethylamine die via cacao wordt toegevoegd verwaarloosbaar is ten opzichte van de hoeveelheid die in tabak zelf aanwezig is. Tot slot is aandacht besteed aan de verbrandingsproducten van cacao. Amine verbindingen als serotonin, tryptofaan, tyramine, tryptamine en fenylethylamine vormen tijdens het roken stoffen die het enzym mono amine oxidase (MAO) remmen. MAO-remmers hebben een anti-depressieve werking en kunnen op die manier bijdragen aan rookverslaving. De conclusie van dit literatuur onderzoek is dat de afzonderlijke psychoactieve stoffen in tabak als gevolg van toevoeging van cacao niet direct bijdragen aan rookverslaving. De verbrandingsproducten van cacao doen dit, via remming van het enzym mono amine oxidase, mogelijk wel. Ook de smaak van cacao wordt geassocieerd met verslaving. De literatuur biedt geen inzicht in het effect op gezondheid en verslaving van het inhaleren van de combinatie van de 10 onderzochte stoffen uit cacao

    Communications and sensing of illumination contributions in a power led lighting system

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    Abstract — In recent years, LED technology emerged as a prime candidate for the future illumination light source, due to high energy efficiency and long life time. In addition, LEDs offer a superior flexibility in terms of colors and shapes, which leads to a potentially infinite variety of available light patterns. In order to create these patterns via easy user interaction, we need to sense the local light contribution of each LED. This measurement could be enabled through tagging of the light of each LED with unique embedded IDs. To this end, we propose a new modulation and multiple access scheme, named as codetime division multiple access- pulse position modulation (CTDMA-PPM): a form of PPM which is keyed according to a spreading sequence, and in which the duty cycle is subject to pulse width modulation (PWM) according to the required lighting setting. Our scheme considers illumination constraints in addition to the communication requirements and, to our best knowledge, it has not been addressed by other optical modulation methods. Based on the proposed modulation method and multiple access schemes, we develop a system structure, which includes illumination sources, a sensor receiver and a control system. Illumination sources illuminate the environment and transmit information, simultaneously. According to our theoretical analysis, this system structure could support a number of luminaries equal to the size of the CDMA codebook times the dimming range. I

    Renminbi Internationalisation: Precedents and Implications

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    While it is commonly assumed that there are no known precedents against which to benchmark the internationalisation of the Renminbi (RMB), this paper argues that the PRCs own development experience provides a useful perspective on the internationalisation debate. In particular it indicates that lessons can be learnt from both the successes and the shortcomings of efforts to internationalise the RMB in the 1970s. During this period state-owned banks in Hong Kong played a central role in mobilising finance for foreign trade. Access to Hong Kong’s developed financial institutions allowed the PRC to maximise receipts from foreign trade as well as minimise the risks of undue swings in capital flows. The paper shows that although China no longer faces foreign exchange scarcity, economic reforms have not yet resolved vulnerabilities in China’s financial institutions and as such Hong Kong’s role in mitigating the risk of undue capital swings remains

    Molecular Geometry of Incommensurate Structures

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    X-ray study of and structural approach to the incommensurate perovskite Pb 2

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