4,435 research outputs found
Observation of Quantum Effects in sub Kelvin Cold Reactions
There has been a long-standing quest to observe chemical reactions at low
temperatures where reaction rates and pathways are governed by quantum
mechanical effects. So far this field of Quantum Chemistry has been dominated
by theory. The difficulty has been to realize in the laboratory low enough
collisional velocities between neutral reactants, so that the quantum wave
nature could be observed. We report here the first realization of merged
neutral supersonic beams, and the observation of clear quantum effects in the
resulting reactions. We observe orbiting resonances in the Penning ionization
reaction of argon and molecular hydrogen with metastable helium leading to a
sharp increase in the absolute reaction rate in the energy range corresponding
to a few degrees kelvin down to 10 mK. Our method is widely applicable to many
canonical chemical reactions, and will enable a breakthrough in the
experimental study of Quantum Chemistry
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Reactions of C+ + Cl-, Br-, and I--A comparison of theory and experiment.
Rate constants for the reactions of C+ + Cl-, Br-, and I- were measured at 300 K using the variable electron and neutral density electron attachment mass spectrometry technique in a flowing afterglow Langmuir probe apparatus. Upper bounds of <10-8 cm3 s-1 were found for the reaction of C+ with Br- and I-, and a rate constant of 4.2 ± 1.1 à 10-9 cm3 s-1 was measured for the reaction with Cl-. The C+ + Cl- mutual neutralization reaction was studied theoretically from first principles, and a rate constant of 3.9 à 10-10 cm3 s-1, an order of magnitude smaller than experiment, was obtained with spin-orbit interactions included using a semiempirical model. The discrepancy between the measured and calculated rate constants could be explained by the fact that in the experiment, the total loss of C+ ions was measured, while the theoretical treatment did not include the associative ionization channel. The charge transfer was found to take place at small internuclear distances, and the spin-orbit interaction was found to have a minor effect on the rate constant
A laser based accelerator for ultracold atoms
We present first results on our implementation of a laser based accelerator
for ultracold atoms. Atoms cooled to a temperature of 420 nK are confined and
accelerated by means of laser tweezer beams and the atomic scattering is
directly observed in laser absorption imaging. The optical collider has been
characterized using Rb87 atoms in the |F=2,mF=2> state, but the scheme is not
restricted to atoms in any particular magnetic substates and can readily be
extended to other atomic species as well.Comment: (c) 2012 The Optical Society, 3 pages, 4 figures, 1 movie lin
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Providing immediate neonatal care and resuscitation at birth beside the mother: parents' views, a qualitative study
Objectives: The aims of this study were to assess parentsâ views of immediate neonatal care and resuscitation at birth being provided beside the mother, and their experiences of a mobile trolley designed to facilitate this bedside care.
Design: Qualitative study with semistructured interviews. Results were analysed using thematic analysis.
Setting: Large UK maternity hospital.
Participants: Mothers whose baby received initial neonatal care in the first few minutes of life at the bedside, and their birth partners, were eligible. 30 participants were interviewed (19 mothers, 10 partners and 1 grandmother). 5 babies required advanced neonatal resuscitation.
Results: 5 themes were identified: (1) Reassurance, which included âBaby is OKâ, âHaving baby closeâ, âConfidence in careâ, âKnowing what's going onâ and âDad as informantâ; (2) Involvement of the family, which included âOpportunity for contactâ, âFamily involvementâ and âNormalityâ; (3) Staff communication, which included âCommunicationâ and âExperienceâ; (4) Reservations, which included âReservations about witnessing resuscitationâ, âNegative emotionsâ and âWorries about the impact on staffâ and (5) Experiences of the trolley, which included âPractical issuesâ and âComparisons with standard resuscitation equipmentâ.
Conclusions: Families were positive about neonatal care being provided at the bedside, and felt it gave reassurance about their baby's health and care. They also reported feeling involved as a family. Some parents reported experiencing negative emotions as a result of witnessing resuscitation of their baby. Parents were positive about the trolley
Nucleon Spin Fluctuations and the Supernova Emission of Neutrinos and Axions
In the hot and dense medium of a supernova (SN) core, the nucleon spins
fluctuate so fast that the axial-vector neutrino opacity and the axion
emissivity are expected to be significantly modified. Axions with
m_a\alt10^{-2}\,{\rm eV} are not excluded by SN~1987A. A substantial transfer
of energy in neutrino-nucleon () collisions is enabled which may alter
the spectra of SN neutrinos relative to calculations where energy-conserving
collisions had been assumed near the neutrinosphere.Comment: 8 pages. REVTeX. 2 postscript figures, can be included with epsf.
Small modifications of the text, a new "Note Added", and three new
references. To be published in Phys. Rev. Let
Irrigated lands assessment for water management: Technique test
A procedure for estimating irrigated land using full frame LANDSAT imagery was demonstrated. Relatively inexpensive interpretation of multidate LANDSAT photographic enlargements was used to produce a map of irrigated land in California. The LANDSAT and ground maps were then linked by regression equations to enable precise estimation of irrigated land area by county, basin, and statewide. Land irrigated at least once in California in 1979 was estimated to be 9.86 million acres, with an expected error of less than 1.75% at the 99% level of confidence. To achieve the same level of error with a ground-only sample would have required 3 to 5 times as many ground sample units statewide. A procedure for relatively inexpensive computer classification of LANDSAT digital data to irrigated land categories was also developed. This procedure is based on ratios of MSS band 7 and 5, and gave good results for several counties in the Central Valley
Guidance and standard operating procedures for functional exercise testing in cystic fibrosis
Regular exercise testing is recommended for all people with cystic fibrosis (PwCF). A range of validated tests, which integrate both strength and aerobic function, are available and increasingly being used. Together, these tests offer the ability for comprehensive exercise evaluation. Extensive research and expert consensus over recent years has enabled the adaptation and standardisation of a range of exercise tests to aid the understanding of the pathophysiology related to exercise limitation in PwCF and has led to the development of novel exercise tests which may be applied to PwCF. This article provides expert, opinion-based clinical practice guidance, along with test instructions, for a selection of commonly used valid tests which have documented clinimetric properties for PwCF. Importantly, this document also highlights previously used tests that are no longer suggested for PwCF and areas where research is mandated. This collaboration, on behalf of the European Cystic Fibrosis Society Exercise Working Group, represents expert consensus by a multidisciplinary panel of physiotherapists, exercise scientists and clinicians and aims to improve global standardisation of functional exercise testing of PwCF. In short, the standardised use of a small selection of tests performed to a high standard is advocated
Getting It on Record: Issues and Strategies for Ethnographic Practice in Recording Studios
The recording studio has been somewhat neglected as a site for ethnographic fieldwork in the field of ethno-musicology and, moreover, the majority of published studies tend to overlook the specific concerns faced by the researcher within these contexts. Music recording studios can be places of creativity, artistry, and collaboration, but they often also involve challenging, intimidating, and fractious relations. Given that recording studios are, first and foremost, concerned with documenting musiciansâ performances, we discuss the concerns of getting studio interactions âon recordâ in terms of access, social relations, and methods of data collection. This article reflects on some of the issues we faced when conducting our fieldwork within British music recording facilities and makes suggestions based on strategies that we employed to address these issues
Psychosocial correlates of attitudes towards male sexual violence in a sample of financial crime, property crime, general violent, and homicide offenders
Whilst those currently serving prison sentences for sexual violence can be identified and receive treatment, the number of prisoners with a history of sexual violence against female partners is unknown. Methods to identify prisoners with a proclivity for such violence and accurately assess the risk they pose before and after incarceration are therefore required. Here, we aimed to assess the level of sexually violent attitudes within dating relationships and to examine their associations with experiences of child abuse and neglect (CAN), psychopathic personality traits, prisonization, number of incarcerations, age, years of schooling, relationship status, and parenting among different types of offenders (financial crime, property crime, general violent, and homicide offenders). Data were collected among a large systematically selected sample of adult male inmates (N = 1,123). We demonstrated that sexual violence-supportive attitudes appear to be a function of child sexual abuse, psychopathic personality traits, and may be developed through early socialisation experiences as well as incarceration. Practical implications of current findings are discussed
A dual process account of creative thinking
This article explicates the potential role played by type 1 thinking (automatic, fast) and type 2 thinking (effortful, logical) in creative thinking. The relevance of Evans's (2007) models of conflict of dual processes in thinking is discussed with regards to creative thinking. The role played by type 1 thinking and type 2 thinking during the different stages of creativity (problem finding and conceptualization, incubation, illumination, verification and dissemination) is discussed. It is proposed that although both types of thinking are active in creativity, the extent to which they are active and the nature of their contribution to creativity will vary between stages of the creative process. Directions for future research to test this proposal are outlined; differing methodologies and the investigation of different stages of creative thinking are discussed. © Taylor & Francis Group, LLC
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