185 research outputs found
How Effectively Are We Managing Innovation?
The writer\u27s observe that top management\u27s stated commitment to innovation has yet to be successfully infused into many organizations
Microscopic model approaches to fragmentation of nuclei and phase transitions in nuclear matter
The properties of excited nuclear matter and the quest for a phase transition
which is expected to exist in this system are the subject of intensive
investigations. High energy nuclear collisions between finite nuclei which lead
to matter fragmentation are used to investigate these properties. The present
report covers effective work done on the subject over the two last decades. The
analysis of experimental data is confronted with two major problems, the
setting up of thermodynamic equilibrium in a time-dependent fragmentation
process and the finite size of nuclei. The present status concerning the first
point is presented. Simple classical models of disordered systems are derived
starting with the generic bond percolation approach. These lattice and cellular
equilibrium models, like percolation approaches, describe successfully
experimental fragment multiplicity distributions. They also show the properties
of systems which undergo a thermodynamic phase transition. Physical observables
which are devised to show the existence and to fix the order of critical
behaviour are presented. Applications to the models are shown. Thermodynamic
properties of finite systems undergoing critical behaviour are advantageously
described in the framework of the microcanonical ensemble. Applications to the
designed models and to experimental data are presented and analysed.
Perspectives of further developments of the field are suggested.Comment: 150 pages including 28 figures. To be published in Phys. Rep.
Corrected discussion in section 3.2.3 and new Fig.5. New caption of Fig.2
NPY Neuron-Specific Y2 Receptors Regulate Adipose Tissue and Trabecular Bone but Not Cortical Bone Homeostasis in Mice
BACKGROUND: Y2 receptor signalling is known to be important in neuropeptide Y (NPY)-mediated effects on energy homeostasis and bone physiology. Y2 receptors are located post-synaptically as well as acting as auto receptors on NPY-expressing neurons, and the different roles of these two populations of Y2 receptors in the regulation of energy homeostasis and body composition are unclear. METHODOLOGY/PRINCIPAL FINDINGS: We thus generated two conditional knockout mouse models, Y2(lox/lox) and NPYCre/+;Y2(lox/lox), in which Y2 receptors can be selectively ablated either in the hypothalamus or specifically in hypothalamic NPY-producing neurons of adult mice. Specific deletion of hypothalamic Y2 receptors increases food intake and body weight compared to controls. Importantly, specific ablation of hypothalamic Y2 receptors on NPY-containing neurons results in a significantly greater adiposity in female but not male mice, accompanied by increased hepatic triglyceride levels, decreased expression of liver carnitine palmitoyltransferase (CPT1) and increased expression of muscle phosphorylated acetyl-CoA carboxylase (ACC). While food intake, body weight, femur length, bone mineral content, density and cortical bone volume and thickness are not significantly altered, trabecular bone volume and number were significantly increased by hypothalamic Y2 deletion on NPY-expressing neurons. Interestingly, in situ hybridisation reveals increased NPY and decreased proopiomelanocortin (POMC) mRNA expression in the arcuate nucleus of mice with hypothalamus-specific deletion of Y2 receptors in NPY neurons, consistent with a negative feedback mechanism between NPY expression and Y2 receptors on NPY-ergic neurons. CONCLUSIONS/SIGNIFICANCE: Taken together these data demonstrate the anti-obesogenic role of Y2 receptors in the brain, notably on NPY-ergic neurons, possibly via inhibition of NPY neurons and concomitant stimulation of POMC-expressing neurons in the arcuate nucleus of the hypothalamus, reducing lipogenic pathways in liver and/or skeletal muscle in females. These data also reveal as an anti-osteogenic effect of Y2 receptors on hypothalamic NPY-expressing neurons on trabecular but not on cortical bone
The James Webb Space Telescope Mission
Twenty-six years ago a small committee report, building on earlier studies,
expounded a compelling and poetic vision for the future of astronomy, calling
for an infrared-optimized space telescope with an aperture of at least .
With the support of their governments in the US, Europe, and Canada, 20,000
people realized that vision as the James Webb Space Telescope. A
generation of astronomers will celebrate their accomplishments for the life of
the mission, potentially as long as 20 years, and beyond. This report and the
scientific discoveries that follow are extended thank-you notes to the 20,000
team members. The telescope is working perfectly, with much better image
quality than expected. In this and accompanying papers, we give a brief
history, describe the observatory, outline its objectives and current observing
program, and discuss the inventions and people who made it possible. We cite
detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space
Telescope Overview, 29 pages, 4 figure
Pengantar komunikasi massa : literasi media dan budaya
Jil.1xxvii,280 p. : il.; 23 cm
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