Experimental limits on monojet production in e+e- annihilation at 29 GeV

A search was made for e+e--->X1X2 where X1 consists of one or more light unobservable particles and X2 decays promptly to a visible jet of particles. One event was found for an integrated luminosity of 176 pb-1, a rate consistent with known backgrounds. This result places a significant constraint on a number of theoretical models.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25641/3/0000191.pd

The vitamin D metabolites 25(OH)D and 1,25(OH)2D are not related to either glucose metabolism or insulin action in obese women

Aim: Vitamin D deficiency has been proposed to be involved in obesity-induced metabolic disease. However, data on the relationship between 25-hydroxycholecalciferol (25(OH)D) and insulin resistance have been inconsistent, and few studies have investigated the active vitamin D metabolite, 1,25-dihydroxycholecalciferol (1,25(OH)2D). This study aimed to determine the relationship between circulating levels of both 25(OH)D and 1,25(OH)2D and direct measures of glucose metabolism and insulin action in obese women. Methods: Serum levels of 25(OH)D and 1,25(OH)2D, and glucose metabolism and tissue-specific insulin action, as assessed in the basal state and during a two-step euglycaemic-hyperinsulinaemic clamp study with [6,6-2H2]glucose infusion, were measured in 37 morbidly obese women (age: 43±10 years; body mass index: 44±6kg/m2). Results: Sixteen subjects had circulating 25(OH)D levels<50nmol/L, consistent with vitamin D deficiency, and 21 had normal 25(OH)D levels. There were no differences in either baseline characteristics or parameters of glucose metabolism and insulin action between the groups. Serum 25(OH)D, but not 1,25(OH)2D, was negatively correlated with both body mass index (r =-0.42, P =0.01) and total body fat (r =-0.46, P <0.01). Neither 25(OH)D nor 1,25(OH)2D levels were related to any measured metabolic parameters, including fasting glucose, fasting insulin, basal endogenous glucose production, and hepatic, adipose-tissue and skeletal muscle insulin sensitivity. Conclusion: Obesity was associated with lower levels of circulating 25(OH)D, but not with the hormonally active metabolite 1,25(OH)2D. Neither 25(OH)D nor 1,25(OH)2D were related to glucose metabolism and tissue-specific insulin sensitivity in obese women, suggesting that vitamin D does not play a major role in obesity-related insulin resistance

Striatal dopamine regulates systemic glucose metabolism in humans and mice

The brain is emerging as an important regulator of systemic glucose metabolism. Accumulating data from animal and observational human studies suggest that striatal dopamine signaling plays a role in glucose regulation, but direct evidence in humans is currently lacking. We present a series of experiments supporting the regulation of peripheral glucose metabolism by striatal dopamine signaling. First, we present the case of a diabetes patient who displayed strongly reduced insulin requirements after treatment with bilateral deep brain stimulation (DBS) targeting the anterior limb of the internal capsule. Next, we show that DBS in this striatal area, which induced dopamine release, increased hepatic and peripheral insulin sensitivity in 14 nondiabetic patients with obsessive-compulsive disorder. Conversely, systemic dopamine depletion reduced peripheral insulin sensitivity in healthy subjects. Supporting these human data, we demonstrate that optogenetic activation of dopamine D1 receptor–expressing neurons in the nucleus accumbens increased glucose tolerance and insulin sensitivity in mice. Together, these findings support the hypothesis that striatal neuronal activity regulates systemic glucose metabolism

COMPARISON OF LIGHT QUARK AND CHARM QUARK FRAGMENTATION

Separate samples of charm quark and light quark (u, d, s) jets have been isolated in an experiment studying e+e- annihilations at s = 29 GeV. The results come from data corresponding to an integrated luminosity of 111 pb-1 collected by the High Resolution Spectrometer. Differences were observed in charged multiplicities, momentum distributions, and rapidity of the size expected from the different fragmentation functions and leading particle decay properties of the two samples. © 1985

COMPARISON OF LIGHT QUARK AND CHARM QUARK FRAGMENTATION

Separate samples of charm quark and light quark (u, d, s) jets have been isolated in an experiment studying e+e- annihilations at s = 29 GeV. The results come from data corresponding to an integrated luminosity of 111 pb-1 collected by the High Resolution Spectrometer. Differences were observed in charged multiplicities, momentum distributions, and rapidity of the size expected from the different fragmentation functions and leading particle decay properties of the two samples. © 1985

Measurement of the F-meson lifetime.

The lifetime of the F meson has been measured to be (3.5-1.8+2.40.9) × 10-13 s by means of the F decay mode. The measurement was made with the High Resolution Spectrometer at the SLAC e+e- storage ring PEP at a center-of-mass energy of 29 GeV. © 1986 The American Physical Society

Comparison of light quark and charm quark fragmentation

Separate samples of charm quark and light quark (u, d, s) jets have been isolated in an experiment studying e+e- annihilations at . The results come from data corresponding to an integrated luminosity of 111 pb-1 collected by the High Resolution Spectrometer. Differences were observed in charged multiplicities, momentum distributions, and rapidity of the size expected from the different fragmentation functions and leading particle decay properties of the two samples.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25527/3/0000068.pd