13,802 research outputs found

    Trends in embryo disposition decisions: patients' responses to a 15-year mailing program

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    BACKGROUND: This study examined the responses of patients of a Belgian fertility center to mailed requests to make or renew an embryo disposition decision (EDD), over a period of 15 years, to investigate trends in the decisions. METHODS: A retrospective analysis was performed on a mailing program from 1992 to 2006, for patients, of the Department of Reproductive Medicine, Ghent University Hospital (Belgium), from whom embryos had been cryopreserved at least 2 years. RESULTS: In 15 years, 3840 EDD forms were prepared for 2334 couples or female patients. The number of forms increased from 21 in 1992 to 558 in 2006. Each year, around a third of the forms were not returned. In general, a quarter of patients who received more than one form never answered. Donation to others for reproduction was overall the least popular option and decreased over the years. The rising trend in decisions to discard reversed into a negative trend from the introduction of donation for science (1997). Since then, donation for science has been the most popular option and its popularity increased with time. In 15 years, 2504 embryos were donated for science. More than a quarter of the patients who chose more than one final EDD in different years did not select the same EDD the second time. CONCLUSIONS: This study showed a positive trend in donation for science and a negative trend in donation to others and discarding. A substantial number of individual patients chose different types of EDDs in consecutive mailings, which shows that advance EDD directives should be used with caution

    Anatomy of extraordinary rainfall and flash flood in a Dutch lowland catchment

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    On 26 August 2010 the eastern part of The Netherlands and the bordering part of Germany were struck by a series of rainfall events lasting for more than a day. Over an area of 740 km2 more than 120 mm of rainfall were observed in 24 h. This extreme event resulted in local flooding of city centres, highways and agricultural fields, and considerable financial loss. In this paper we report on the unprecedented flash flood triggered by this exceptionally heavy rainfall event in the 6.5 km2 Hupsel Brook catchment, which has been the experimental watershed employed by Wageningen University since the 1960s. This study aims to improve our understanding of the dynamics of such lowland flash floods. We present a detailed hydrometeorological analysis of this extreme event, focusing on its synoptic meteorological characteristics, its space-time rainfall dynamics as observed with rain gauges, weather radar and a microwave link, as well as the measured soil moisture, groundwater and discharge response of the catchment. At the Hupsel Brook catchment 160 mm of rainfall was observed in 24 h, corresponding to an estimated return period of well over 1000 years. As a result, discharge at the catchment outlet increased from 4.4 × 10-3 to nearly 5 m3 s-1. Within 7 h discharge rose from 5 × 10-2 to 4.5 m3 s-1. The catchment response can be divided into four phases: (1) soil moisture reservoir filling, (2) groundwater response, (3) surface depression filling and surface runoff and (4) backwater feedback. The first 35 mm of rainfall were stored in the soil without a significant increase in discharge. Relatively dry initial conditions (in comparison to those for past discharge extremes) prevented an even faster and more extreme hydrological response

    Future directions in kaonic atom physics

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    Recent progress and open problems in kaonic atom physics are presented. A connection between phenomenological deep potentials and the underlying KNK^-N interaction is established as well as the need for a theory for multinucleon absorption of kaons. KK^- absorption at rest to specific Λ\Lambda hypernuclei states is briefly discussed.Comment: 6 pages, 3 figures, proceedings of the EXA2011 conference, to appear in Hyperfine Interaction

    Mach's Principle and Model for a Broken Symmetric Theory of Gravity

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    We investigate spontaneous symmetry breaking in a conformally invariant gravitational model. In particular, we use a conformally invariant scalar tensor theory as the vacuum sector of a gravitational model to examine the idea that gravitational coupling may be the result of a spontaneous symmetry breaking. In this model matter is taken to be coupled with a metric which is different but conformally related to the metric appearing explicitly in the vacuum sector. We show that after the spontaneous symmetry breaking the resulting theory is consistent with Mach's principle in the sense that inertial masses of particles have variable configurations in a cosmological context. Moreover, our analysis allows to construct a mechanism in which the resulting large vacuum energy density relaxes during evolution of the universe.Comment: 9 pages, no figure
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