7,139 research outputs found

    Once more about gauge invariance in \phi\to\gamma\pi0\pi0

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    It is argued that the realization of gauge invariance condition as a consequent of cancellation between the \phi\to\gamma f0\to\gamma\pi0\pi0 resonance contribution and a \phi\to\gamma\pi0\pi0 background one, suggested in Ref. [1], is misleading.Comment: 4 pages, one reference adde

    Scanning Electron Microscopy of Thebesian Ostia (Microdissection by Ultrasonication: Enzymatic Digestion)

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    Thebesian vasculature provides for communication between the coronary system and the chambers of the heart. Anatomic, embryologic, physiologic, and therapeutic investigations have involved this component of cardiac anatomy from the early 18th century to the present time. The scanning electron microscope (SEM) now affords an innovative approach to the study of the ostia of these veins as they open into the chambers of the heart. The surface of the intact endocardium is continuous, whether it is treated with boric acid or not, as long as it remains intact. Enzymatic microdissection of tissues with trypsin, hyaluronidase and pronase, followed by similar treatment with boric acid, reveals continuity of successive component layers of the endocardium extending into Thebesian substructure. Thebesian tributaries are easily visualized from the ostia but the deeper capillary network of the Thebesian system is not demonstrable by this approach. Valvular structures such as might prevent retroflow during the cardiac cycle are not present. Our observations with SEM support anatomic relationships indicated by previously published work

    Chlamydia control activities in Europe: cross-sectional survey

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    Background: Chlamydia is the most commonly reported bacterial sexually transmitted infection in Europe. The objective of the Screening for Chlamydia in Europe (SCREen) project was to describe current and planned chlamydia control activities in Europe. Methods: The authors sent a questionnaire asking about different aspects of chlamydia epidemiology and control to public health and clinical experts in each country in 2007. The principles of sexually transmitted infection control were used to develop a typology comprising five categories of chlamydia control activities. Each country was assigned to a category, based on responses to the questionnaire. Results: Experts in 29 of 33 (88%) invited countries responded. Thirteen of 29 countries (45%) had no current chlamydia control activities. Six countries in this group stated that there were plans to introduce chlamydia screening programmes. There were five countries (17%) with case management guidelines only. Three countries (10%) also recommended case finding amongst partners of diagnosed chlamydia cases or people with another sexually transmitted infection. Six countries (21%) further specified groups of asymptomatic people eligible for opportunistic chlamydia testing. Two countries (7%) reported a chlamydia screening programme. There was no consistent association between the per capita gross domestic product of a country and the intensity of chlamydia control activities (P = 0.816). Conclusion: A newly developed classification system allowed the breadth of ongoing national chlamydia control activities to be described and categorized. Chlamydia control strategies should ensure that clinical guidelines to optimize chlamydia diagnosis and case management have been implemented before considering the appropriateness of screening programmes

    Corrections to deuterium hyperfine structure due to deuteron excitations

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    We consider the corrections to deuterium hyperfine structure originating from the two-photon exchange between electron and deuteron, with the deuteron excitations in the intermediate states. In particular, the motion of the two intermediate nucleons as a whole is taken into account. The problem is solved in the zero-range approximation. The result is in good agreement with the experimental value of the deuterium hyperfine splitting.Comment: 7 pages, LaTe

    A triclinic polymorph of benzanilide : disordered molecules form hydrogen-bonded chains

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    Peer reviewedPublisher PD

    Intermolecular N-H...O=C hydrogen bonding in the crystal structure of 6-amino-1,3-dimethyluracil

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    The 6-amino- 1,3-dimethyluracil molecule [6-amino- 1,3- dimethyl-2,4(1H,3H)-pyrimidinedione], C6H9N302 (I), lies on a crystallographic mirror plane and participates in an extensive two-dimensional hydrogen-bonding network in the solid state. Each molecule is involved in N-- H...O=C hydrogen bonding involving the amino and carbonyl gr. oups, with O...N separations of 2.894 (3) and 2.904 (3) A

    Ultrasonic Microdissection of Rat Cerebellum for Scanning Electron Microscopy

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    The cerebelli of rats were initially fixed with aldehydes (modified Karnovsky\u27s fixative; 503 mOsM/L) by cardiac perfusion. Blocks of tissue were razor-cut, usually longitudinal to folia, and immersed in the same fluid for 2-4 hours. Three separate methods of treatment followed: (1) immersion in 1% aqueous boric acid, or (2) in 2% phosphate buffered OsO4 followed by boric acid or (3) in an 8/2 mixture of boric acid and OsO4. After 18-48 hours immersion the blocks were dehydrated in ascending grades of acetone. They were then exposed to ultrasound in 100% acetone at frequencies of 80 kHz or 40 kHz for 10 to 20 minutes. Microdissection of cut surfaces (erosion) occurs after all three treatments. It is least extensive after boric acid, moderate after OsO4 and greatest after the combined mixture. All cerebellar cell types are recognizable as are numerous fibers according to morphology and position. Variable erosion accommodates analysis of different levels of neural organization. In general, structural situations not involving great depth of field are best revealed by H3BO3 or OsO4. Blood vascular relationships to other structures are best demonstrated in deeply eroded specimens

    One size doesn't fit all: Tailoring adult antiretroviral treatment

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    Advances in antiretroviral treatment mean that patients in the public health system can be given more options in the management of their treatment. Although public health programmes tend to offer one-size-fits-all approaches, patients might benefit from a more flexible approach. In particular, we propose that people with HIV should be given more choice with regard to when to start treatment, and patients who experience efavirenz side-effects should be encouraged to switch to other medications, which will be facilitated by faster registration and lower prices of newer antiretrovirals

    Diffraction and the Pomeron

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    Recent experimental results on inclusive diffractive scattering and on exclusive vector meson production are reviewed. The dynamical picture of hard diffraction emerging in perturbative QCD is highlighted.Comment: 25 pages, 21 postscript figures, contribution to the XIX International Symposium on Lepton and Photon Interactions at High Energies, Stanford University, August 9-14, 199
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