4,513 research outputs found
Development of an orbit determination program to regress for lunar potential constants
Orbit calculation program modified to provide corrected state vectors for lunar potential constants in moon centered coordinate syste
Short versus long range interactions and the size of two-body weakly bound objects
Very weakly bound systems may manifest intriguing "universal" properties,
independent of the specific interaction which keeps the system bound. An
interesting example is given by relations between the size of the system and
the separation energy, or scaling laws. So far, scaling laws have been
investigated for short-range and long-range (repulsive) potentials. We report
here on scaling laws for weakly bound two-body systems valid for a larger class
of potentials, i.e. short-range potentials having a repulsive core and
long-range attractive potentials. We emphasize analogies and differences
between the short- and the long-range case. In particular, we show that the
emergence of halos is a threshold phenomenon which can arise when the system is
bound not only by short-range interactions but also by long-range ones, and
this for any value of the orbital angular momentum . These results
enlarge the image of halo systems we are accustomed to.Comment: 6 pages, 1 figure. To be published in the Proceedings of the Workshop
"Hirschegg 2003: Nuclear Structure and Dynamics at the Limits", Hirschegg,
January 12 - 18, 200
Description of Heavy Quark Systems by means of Energy Dependent Potentials
We apply, for the first time, an energy dependent Schrodinger equation to
describe static properties of heavy quark systems, i.e. charmonium and
bottonium. We show that a good description of the eigenstates and reasonable
values for the widths can be obtained. Values of the radii and of the density
at the origin are also given. We compare the results to those deduced with a
Schrodinger equation implemented with potentials used so far. We note that the
energy dependence of the confining potential provides a natural mechanism for
the saturation of the spectra. Our results introduce a new class of potentials
for the description of heavy quark systems.Comment: 3 page
Influence of the electron-phonon interfacial conductance on the thermal transport at metal/dielectric interfaces
Thermal boundary conductance at a metal-dieletric interface is a quantity of
prime importance for heat management at the nanoscale. While the boundary
conductance is usually ascribed to the coupling between metal phonons and
dielectric phonons, in this work we examine the influence of a direct coupling
between the metal electrons and the dielectric phonons. The effect of electron-
phonon processes is generally believed to be resistive, and tends to decrease
the overall thermal boundary conductance as compared to the phonon-phonon
conductance {\sigma}p . Here, we find that the effect of a direct coupling
{\sigma}e is to enhance the effective thermal conductance, between the metal
and the dielectric. Resistive effects turn out to be important only for thin
films of metals having a low electron-phonon coupling strength. Two approaches
are explored to reach these conclusions. First, we present an analytical
solution of the two-temperature model to compute the effective conductance
which account for all the relevant energy channels, as a function of {\sigma}e
, {\sigma}p and the electron-phonon coupling factor G. Second, we use numerical
resolution to examine the influence of {\sigma}e on two realistic cases: gold
film on silicon or silica substrates. We point out the implications for the
interpretation of time-resolved thermoreflectance experiments
The development of an advanced system to cool a man in a pressure suit
Conductive cooling system for cooling man in pressurized space sui
Complex potentials and the inverse problem
The occurrence of complex potentials with real eigenvalues has implications concerning the inverse problem, i.e. the determination of a potential from its spectrum. First, any complex potential with real eigenvalues has at least one equivalent local potential. Secondly, a real spectrum does not necessarily corresponds to a local real potential. A basic ambiguity arises from the possibility the spectrum to be generated by a complex potential. The purpose of this work is to discuss several aspects of this problem
Cound, Friedenthal & Miller: Civil Procedure, Cases and Materials
A Book Review of Civil Procedure, Cases and Materials by John J. Coun
Mercury deposition in southern New Hampshire, 2006–2009
The atmospheric deposition of mercury (Hg) occurs via several mechanisms including wet, dry, and occult processes. In an effort to understand the atmospheric cycling and seasonal depositional characteristics of Hg, event-based wet deposition samples and reactive gaseous Hg (RGM) measurements were collected for approximately 3 years at Thompson Farm (TF), a near-coastal rural site in Durham, NH, part of the University of New Hampshire AIRMAP Observing Network. Total aqueous mercury exhibited seasonal patterns in Hg wet deposition at TF. The lowest Hg wet deposition was measured in the winter with an average total seasonal deposition of 1.56 μg m−2compared to the summer average of 4.71 μg m−2. Inter-annual differences in total wet deposition are generally linked with precipitation volume, with the greatest deposition occurring in the wettest year. Relationships between surface level RGM and Hg wet deposition were also investigated based on continuous RGM measurements at TF from November 2006 to September 2009. No correlations were observed between RGM mixing ratios and Hg wet deposition, however the ineffective scavenging of RGM during winter precipitation events was evidenced by the less frequent depletion of RGM below the detection level. Seasonal dry deposition of reactive gaseous Hg (RGM) was estimated using an order-of-magnitude approach. RGM mixing ratios and dry deposition estimates were greatest during the winter and spring. The seasonal ratios of Hg wet deposition to RGM dry deposition vary by up to a factor of 80
Nucleation in dilute 3He-4He liquid mixtures at low temperatures
We present a study of phase separation from supersaturated 3He-4He liquid
mixtures at low temperatures addressing both the degree of critical
supersaturation Dx and the thermal-to-quantum crossover temperature T* for the
nucleation process. Two different nucleation seeds are investigated, namely 3He
droplets and 4He vortex lines with cores filled with 3He. We have found that
the experimental T* is reproduced when we consider that nucleation proceeds
from 3He droplets, whereas Dx is reproduced when we consider 4He vortex lines
filled with 3He. However, neither nucleation configuration is able to
simultaneously reproduce the current experimental information on Dx and T*.Comment: To appear in J. of Low Temp. Physic
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