A first experimental demonstration of a new type of magnetic trap for ultra-cold neutrons is presented. High-field seeking spin-states are trapped in a potential formed by the magnetic field of a ...straight wire and a repulsive coating on the wire surface. Life-times of the trapped neutrons of 60 s could be observed. This configuration can in principle be used to form bound states of the wave function on the surface of the wire to probe new forces at short distances. Further applications include the use as a guide and selector for perfectly polarized neutrons.
The extreme sib-pair approach has been shown to be a powerful strategy to identify susceptibility loci linked to quantitative traits. The body mass index is the usually assessed trait in genetic ...studies on human obesity. Environmental factors clearly play an important role for this trait. We hypothesized that the low weight of most sibs who were seemingly discordant to the obese index proband was influenced by other environmental and/or genetic factors like restrained eating or psychiatric disorders.
A screening questionnaire was sent to parents of all consecutively admitted patients three weeks prior to referral of index probands for inpatient treatment of obesity. The first 320 families were further investigated. Twenty-seven seemingly extremely discordant sib-pairs (ED) were identified and examined in detail.
The low weight of most sibs who were seemingly discordant to the obese index proband was influenced by factors like restrained eating or psychiatric disorders. Only 20% of the interviewed ED could be considered as genuine ED.
We conclude that extensive medical evaluation is necessary if the aim is to guarantee genuine ED in family studies for human obesity. Non-paternity deserves specific attention in ED studies.
Looking for surface states of ultra-cold neutrons Brenner, Th; Butterworth, J; Geltenbort, P ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
2000, Letnik:
440, Številka:
3
Journal Article
Recenzirano
We report experiments testing the question whether or not ultra-cold neutrons (UCN) stored in traps with total-reflecting walls are temporarily adsorbed to the walls. A hypothetical process of ...sticking to the walls is theoretically intriguing but it can apparently make plausible the puzzling observations made in UCN storage experiments over the years.
In unconventional storage experiments we filled ultracold neutrons (UCN) into a Fomblin-grease coated trap and then immediately removed the UCN from the storage volume by an absorber, until their ...residual density in the trap was measured to be negligible. When subsequently the absorber was withdrawn a significant number of UCN of higher energies emerged from the trap. Their appearance cannot be attributed to heating or cooling of residual UCN. Further experiments were performed to investigate the origin of these UCN which we call `late UCN'. We noticed that application of a magnetic field gradient at the trap wall as well as a replacement of Fomblin grease on the surface by Fomblin oil gave rise to small but measurable alterations of storage behavior. These phenomena are consistent with the hypothesis of temporary adhesion of a few UCN to a rough wall.
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