3,108 research outputs found
Investigation of DC-8 nacelle modifications to reduce fan-compressor noise in airport communities. Part 5 - Economic implications of retrofit Technical report, May 1967 - Oct. 1969
Economic impact of modifications to DC-8 aircraft nacelles to reduce fan-compressor noise - Part
Krylov-Bogoliubov-Mitropolsky Averaging Used to Construct Effective Hamiltonians in the Theory of Strongly Correlated Electron Systems
We show that the Krylov-Bogoliubov-Mitropolsky averaging in the canonical
formulation can be used as a method for constructing effective Hamiltonians in
the theory of strongly correlated electron systems. As an example, we consider
the transition from the Hamiltonians of the Hubbard and Anderson models to the
respective Hamiltonians of the t-J and Kondo models. This is a very general
method, has several advantages over other methods, and can be used to solve a
wide range of problems in the physics of correlated systems.Comment: 9 page
Supported magnetic nanoclusters: Softlanding of Pd clusters on a MgO surface
Low-energy deposition of neutral Pd_N clusters (N=2-7 and 13) on a MgO(001)
surface F-center (FC) was studied by spin-density-functional molecular dynamics
simulations. The incident clusters are steered by an attractive "funnel"
created by the FC, resulting in adsorption of the cluster, with one of its
atoms bonded atop of the FC. The deposited Pd_2-Pd_6 clusters retain their
gas-phase structures, while for N>6 surface-commensurate isomers are
energetically more favorable. Adsorbed clusters with N > 3 are found to remain
magnetic at the surface.Comment: 5 pages, 2 figs, Phys.Rev.Lett., accepte
Microminiaturized, biopotential conditioning system (MBCS)
Multichannel, medical monitoring system allows almost complete freedom of movement for subject during monitoring periods. System comprises monitoring unit (biobelt), transmission line, and data acquisition unit. Belt, made of polybenzimidizole fabric, is wrapped around individual's waist and held in place by overlapping sections of Velcro closure material
Investigation of DC-8 nacelle modifications to reduce fan-compressor noise in airport communities. Part 4 - Flight acoustical and performance evaluations, for period May 1967 - October 1969
Flight acoustical and performance evaluations of DC 8 nacelle modifications to reduce fan-compressor noise in airport communitie
Patient and provider characteristics associated with communication about opioids: An observational study
Objective
Our objective is to examine the relationship of patient and provider characteristics and communication with chronic non-cancer pain and opioid management in primary care.
Method
We conducted an observational study using audio-recorded primary care appointments (up to 3/patient) and self-reported assessments of primary care providers (PCPs) and patients. We coded visit transcripts for 1) opioid and pain management talk and 2) mental health and opioid safety talk.
Results
Eight PCPs and 30 patients had complete data for 78 clinic visits. PCPs and patients engaged in more opioid and pain management talk when patients reported greater pain catastrophizing and PCPs reported higher psychosocial orientation. PCPs and patients engaged in talk about mental health and opioid safety when patients reported greater anxiety, higher working alliance with their PCP, and when PCPs reported higher burnout. PCPs’ negative attitudes about opioids were associated with fewer discussions about mental health and opioid safety.
Conclusions
Our results should facilitate design of interventions that improve communication and, ultimately, pain outcomes for patients.
Practice Implications
Clinicians can use our results to increase patient engagement in discussions about opioid use and pain management or mental health and safety discussions
The Milky Way rotation curve in Horava - Lifshitz theory
The Horava - Lifshitz (HL) theory has recently attracted a lot of interest as
a viable solution to some quantum gravity related problems and the presence of
an effective cosmological constant able to drive the cosmic speed up. We show
here that, in the weak field limit, the HL proposal leads to a modification of
the gravitational potential because of two additive terms (scaling respectively
as and ) to the Newtonian potential. We then derive a
general expression to compute the rotation curve of an extended system under
the assumption that the mass density only depends on the cylindrical
coordinates showing that the HL modification induces a dependence of
the circular velocity on the mass function which is a new feature of the
theory. As a first exploratory analysis, we then try fitting the Milky Way
rotation curve using its visible components only in order to see whether the HL
modified potential can be an alternative to the dark matter framework. This
turns out not to be the case so that we argue that dark matter is still needed,
but the amount of dark matter and the dark halo density profile have to be
revised according to the new HL potential.Comment: 10 pages, 1 figure, accepted for publication on MNRA
Measurement of the solar neutrino capture rate with gallium metal
The solar neutrino capture rate measured by the Russian-American Gallium
Experiment (SAGE) on metallic gallium during the period January 1990 through
December 1997 is 67.2 (+7.2-7.0) (+3.5-3.0) SNU, where the uncertainties are
statistical and systematic, respectively. This represents only about half of
the predicted Standard Solar Model rate of 129 SNU. All the experimental
procedures, including extraction of germanium from gallium, counting of 71Ge,
and data analysis are discussed in detail.Comment: 34 pages including 14 figures, Revtex, slightly shortene
How many sigmas is the solar neutrino effect?
The minimal standard electroweak model can be tested by allowing all the
solar neutrino fluxes, with undistorted energy spectra, to be free parameters
in fitting the measured solar neutrino event rates, subject only to the
condition that the total observed luminosity of the sun is produced by nuclear
fusion. The rates of the five experiments prior to SNO (chlorine, Kamiokande,
SAGE, GALLEX, Super-Kamiokande) cannot be fit by an arbitrary choice of
undistorted neutrino fluxes at the level of 2.5 sigma (formally 99% C.L.).
Considering just SNO and Super-Kamiokande, the discrepancy is at the 3.3 sigma
level(10^{-3} C.L.). If all six experiments are fit simultaneously, the formal
discrepancy increases to 4 sigma (7*10^{-5} C.L.). If the relative scaling in
temperature of the nuclear reactions that produce 7Be and 8B neutrinos is taken
into account, the formal discrepancy is at the 7.4 sigma level.Comment: 1 figure; related information at http://www.sns.ias.edu/~jn
Solar Neutrinos and the Violation of Equivalence Principle
In this Brief Report, a non-standard solution to the solar neutrino problem
is revisited. This solution assumes that neutrino flavors could have different
couplings to gravity, hence, the equivalence principle is violated in this
mechanism. The gravity induced mixing has the potential of accounting for the
current solar neutrino data from several experiments even for massless
neutrinos. We fit this solution to the total rate of neutrino events in the
SuperKamiokande detector together with the total rate from other detectors and
also with the most recent results of the SuperKamiokande results for the
recoil-electron spectrum.Comment: 6 pages, 4 figures, submitted to Phys.Rev.
- …