14,957 research outputs found
The preparation of ultra fine beryllium powder by the amalgam process Technical report
Beryllium powder production by electrolysis of beryllium chloride-sodium chloride molten eutectic mixtur
Correlation inequalities for noninteracting Bose gases
For a noninteracting Bose gas with a fixed one-body Hamiltonian H^0
independent of the number of particles we derive the inequalities _N <
_{N+1}, _N _N _N for i\neq j, \partial
_N/\partial \beta >0 and ^+_N _N. Here N_i is the occupation
number of the ith eigenstate of H^0, \beta is the inverse temperature and the
superscript + refers to adding an extra level to those of H^0. The results
follow from the convexity of the N-particle free energy as a function of N.Comment: a further inequality adde
Choice of Consistent Family, and Quantum Incompatibility
In consistent history quantum theory, a description of the time development
of a quantum system requires choosing a framework or consistent family, and
then calculating probabilities for the different histories which it contains.
It is argued that the framework is chosen by the physicist constructing a
description of a quantum system on the basis of questions he wishes to address,
in a manner analogous to choosing a coarse graining of the phase space in
classical statistical mechanics. The choice of framework is not determined by
some law of nature, though it is limited by quantum incompatibility, a concept
which is discussed using a two-dimensional Hilbert space (spin half particle).
Thus certain questions of physical interest can only be addressed using
frameworks in which they make (quantum mechanical) sense. The physicist's
choice does not influence reality, nor does the presence of choices render the
theory subjective. On the contrary, predictions of the theory can, in
principle, be verified by experimental measurements. These considerations are
used to address various criticisms and possible misunderstandings of the
consistent history approach, including its predictive power, whether it
requires a new logic, whether it can be interpreted realistically, the nature
of ``quasiclassicality'', and the possibility of ``contrary'' inferences.Comment: Minor revisions to bring into conformity with published version.
Revtex 29 pages including 1 page with figure
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Exercise addiction – the emergence of a new disorder
An optimal level of regular physical activity plays an important role in the maintenance of physical and mental health. However, excessive exercise in a minority of individuals can have adverse effects on health and lead to exercise addiction. Exercise addiction can be conceptualised as a behavioural addiction. The aim of this paper is to outline the current knowledge on the concept, epidemiology, aetiology, comorbidity, and possible interventions of exercise addiction
Positionally dependent ^(15)N fraction factors in the UV photolysis of N_2O determined by high resolution FTIR spectroscopy
Positionally dependent fractionation factors for the photolysis of isotopomers of N_2O in natural abundance have been determined by high resolution FTIR spectroscopy at three photolysis wavelengths. Fractionation factors show clear 15N position and photolysis wavelength dependence and are in qualitative agreement with theoretical models but are twice as large. The fractionation factors increase with photolysis wavelength from 193 to 211 nm, with the fractionation factors at 207.6 nm for ^(14)N^(15)N^916)O, ^(15)N^(14)N^(16)O and ^(14)N^(14)N^(18)O equal to −66.5±5‰,−27.1±6‰ and −49±10‰, respectively
Ultra-fine beryllium powder by amalgam process Progress report, period ending 31 Oct. 1966
Metallurgical evaluation of beryllium powdered metal, and electron microscope studies of agglomerate particle size
The Paradoxical Forces for the Classical Electromagnetic Lag Associated with the Aharonov-Bohm Phase Shift
The classical electromagnetic lag assocated with the Aharonov-Bohm phase
shift is obtained by using a Darwin-Lagrangian analysis similar to that given
by Coleman and Van Vleck to identify the puzzling forces of the Shockley-James
paradox. The classical forces cause changes in particle velocities and so
produce a relative lag leading to the same phase shift as predicted by Aharonov
and Bohm and observed in experiments. An experiment is proposed to test for
this lag aspect implied by the classical analysis but not present in the
currently-accepted quantum topological description of the phase shift.Comment: 8 pages, 3 figure
Trials and evaluation of an RD Instruments Acoustic Correlation Current Profiler in the Agulhas Current on RRS "Discovery" Cruise 214
Gateway-pathway heritage and urban growth zagreb case study
This paper is a part of on-going research into the typological definition of 'urban gateway-pathways'. This term refers to routes used to connect peripheral settlements to the urban core of contemporary cities. The typology was developed with reference to a sample of 18 Central European cities that were formerly provincial capital cities of the Austro-Hungarian monarchy. This paper provides the first authoritative syntactical description of the city of Zagreb and reports on initial syntactical analysis of its historic pathway typology using the transect method established by Hi II ier (1999). The results from the transect analysis are then used to provide more refined typological descriptions of the gateway-pathways and their historical transformations, and to frame a future phase of research using segment analysis
Thermal Studies on Rubidium Dinitramide
The present study has been carried out to investigate conflicting reports in the literature on the nature of the thermal decomposition of the energetic oxidant rubidium dinitramide in the liquid state. The techniques employed included DSC, simultaneous TG-DTA, simultaneous TG-mass spectrometry and thermomicroscopy. The measurements were supplemented by quantitative chemical analysis of the reaction products. The results showed that, following fusion at 106 °C, the overall decomposition proceeded in a single exothermic reaction stage forming a mixture of rubidium nitrate and rubidium nitrite in the molar ratio 1.2 : 1
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