214 research outputs found
Phase transition in exotic nuclei along the line
The abrupt structure change from the nuclei of to those of is investigated by means of shell model calculations. The basic
features of the even-even and odd-odd nuclei under consideration are nicely
reproduced. A sudden jump of nucleons into the upper shell at
is found to be the main reason that causes the qualitative structure
difference. It is argued that the structure change can be viewed as a decisive
change of the mean field, or a phase transition, along the line.Comment: 4 pages, 5 figures, submitted to Phys. Rev. Let
A new type of carbon resistance thermometer with excellent thermal contact at millikelvin temperatures
Using a new brand of commercially available carbon resistor we built a
cryogenic thermometer with an extremely good thermal contact to its thermal
environment. Because of its superior thermal contact the thermometer is
insensitive to low levels of spurious radio frequency heating. We calibrated
our thermometer down to 5mK using a quartz tuning fork He-3 viscometer and
measured its thermal resistance and thermal response time.Comment: 5 pages, 4 figure
Continuum quasiparticle random phase approximation and the time dependent Hartree-Fock-Bogoliubov approach
Quadrupole excitations of neutron-rich nuclei are analyzed by using the
linear response method in the Quasiparticle Random Phase Approximation (QRPA).
The QRPA response is derived starting from the time-dependent
Hartree-Fock-Bogoliubov (HFB) equations. The residual interaction between the
quasiparticles is determined consistently from the two-body force used in the
HFB equations, and the continuum coupling is treated exactly.
Calculations are done for the neutron-rich oxygen isotopes. It is found that
pairing correlations affect the low-lying states, and that a full treatment of
the continuum can change the structure of the states in the giant resonance
region.Comment: 17 pages, 7 figures. Revised version with comments and references
adde
Thermal diffusivity and Biot number: a new experimental method
A new simple method is presented for measuring thermal diffusivity and Biot number in cylindrical samples made of relatively highly conducting materials, subjected to laminar air flow. The basic idea is a heat source in the middle section of the sample, acting also as a thermocouple; only one additional temperature sensor at the cylinder basis is required to give all information, without requiring any hypothesis about the effective time dependence of the heat source
Neural cytoskeleton capabilities for learning and memory
This paper proposes a physical model involving the key structures within the neural cytoskeleton as major players in molecular-level processing of information required for learning and memory storage. In particular, actin filaments and microtubules are macromolecules having highly charged surfaces that enable them to conduct electric signals. The biophysical properties of these filaments relevant to the conduction of ionic current include a condensation of counterions on the filament surface and a nonlinear complex physical structure conducive to the generation of modulated waves. Cytoskeletal filaments are often directly connected with both ionotropic and metabotropic types of membrane-embedded receptors, thereby linking synaptic inputs to intracellular functions. Possible roles for cable-like, conductive filaments in neurons include intracellular information processing, regulating developmental plasticity, and mediating transport. The cytoskeletal proteins form a complex network capable of emergent information processing, and they stand to intervene between inputs to and outputs from neurons. In this manner, the cytoskeletal matrix is proposed to work with neuronal membrane and its intrinsic components (e.g., ion channels, scaffolding proteins, and adaptor proteins), especially at sites of synaptic contacts and spines. An information processing model based on cytoskeletal networks is proposed that may underlie certain types of learning and memory
Epilithic diatoms in headwater areas of the hydrographical sub-basin of the Andreas Stream, RS, Brazil, and their relation with eutrophication processes
Efficacy of an additional flap operation in bladder-preserving surgery with radical prostatectomy and cystourethral anastomosis for rectal cancer involving the prostate
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