34,346 research outputs found
Newton's "Experimental Philosophy"
My talk today will be about Newtonâs avowed methodology, and specifically the place of experiment in his conception of science, and how his ideas changed significantly over the course of his career. I also want to look at his actual scientific practice and see how this influenced his views on the nature of the experimental sciences
Principles of equilibrium statistical mechanics revisited: The idea of vortex energy
We show that the law of energy conservation with the fact of matter stability
imply the existence of energy complementary to that given by the function of
states of interacting systems and treated, with the environment, the function
of states of interacting extended systems. The complementary energy, we called
it vortex, is integral, not quantized, and causes trends contrary to that
prescribed by equilibrium statistical mechanics. We formulate its principles
and theorems, and question traditional insights in thermodynamics, entropy law,
phase transitions, persistent currents, Brownian motion.Comment: 8 pages. Refined the title and wording, corrected typos, added the
acknowledgement. arXiv admin note: substantial text overlap with
arXiv:1109.2605; refined the title, clarified some phrases, refined
concluding remarks, results unchange
Photoassociation adiabatic passage of ultracold Rb atoms to form ultracold Rb_2 molecules
We theoretically explore photoassociation by Adiabatic Passage of two
colliding cold ^{85}Rb atoms in an atomic trap to form an ultracold Rb_2
molecule. We consider the incoherent thermal nature of the scattering process
in a trap and show that coherent manipulations of the atomic ensemble, such as
adiabatic passage, are feasible if performed within the coherence time window
dictated by the temperature, which is relatively long for cold atoms. We show
that a sequence of ~2*10^7 pulses of moderate intensities, each lasting ~750
ns, can photoassociate a large fraction of the atomic ensemble at temperature
of 100 microkelvin and density of 10^{11} atoms/cm^3. Use of multiple pulse
sequences makes it possible to populate the ground vibrational state. Employing
spontaneous decay from a selected excited state, one can accumulate the
molecules in a narrow distribution of vibrational states in the ground
electronic potential. Alternatively, by removing the created molecules from the
beam path between pulse sets, one can create a low-density ensemble of
molecules in their ground ro-vibrational state.Comment: RevTex, 23 pages, 9 figure
Orbital Magnetism in Two-dimensional Integrable Systems
We study orbital magnetism of a degenerate electron gas in a number of
two-dimensional integrable systems, within linear response theory. There are
three relevant energy scales: typical level spacing, the energy related to the
inverse time of flight across the system, and the Fermi energy.
Correspondingly, there are three distinct temperature regimes: microscopic,
mesoscopic, and macroscopic. In the first two regimes there are large
finite-size effects in the magnetic susceptibility, whereas in the third regime
the susceptibility approaches its macroscopic value. In some cases, such as a
quasi-one-dimensional strip or a harmonic confining potential, it is possible
to obtain analytic expressions for the susceptibility in the entire temperature
range.Comment: 28 pages, Latex, 4 Postscript figure
Judicial Incentives and Indeterminacy in Substantive Review of Administrative Decisions
Uppsatsen tydliggör och beskriver innehĂ„llet i elva lokala överenskommelser (LĂK) mellan civilsamhĂ€llet och offentlig sektor. Studien visar ocksĂ„ hur relationen mellan parterna avspeglas i texterna. Uppsatsen visar ocksĂ„ pĂ„ hur olika idĂ©er och synsĂ€tt i överenskommelserna kan fĂ„ praktiska konsekvenser för civilsamhĂ€llet
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