80,196 research outputs found
On Deriving Space-Time From Quantum Observables and States
We prove that, under suitable assumptions, operationally motivated data
completely determine a space-time in which the quantum systems can be
interpreted as evolving. At the same time, the dynamics of the quantum system
is also determined. To minimize technical complications, this is done in the
example of three-dimensional Minkowski space.Comment: 19 pages, to appear in Communications in Mathematical Physics; minor
corrections mad
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CO J = 3→2 and J = 2→1 mapping and spectroscopy of NGC 7027
We present spectra and mapping for NGC 7072 in the J = 3→2 and J = 2→1 transitions of CO. The central profile at J = 2→1 is shown to be very similar to the J = 1→0 spectrum measured by Thronson (1983), and this implies a source expansion at roughly constant velocity. The J = 3→2 line however appears weaker, with evidence for appreciable quenching of the higher velocity components. Detailed modelling f the source indicates that densities n must vary appreciably with shell radius R(as nα R-a, where α≥2), and this leads to a corresponding steep radial decrease in the radiation temperature TR. In consequence, the source FWHM is found to decrease appreciably iwth increasing transition frequency, a trend which appears also to be confirmed by our central J = 3→2 scans. It is not however possible to constrain gas kinetic tempertures TK, the level of CO thermalisation, or shell mass M with any degree of confidence - both low and high mass models appear capable of replicating our spectra.
Finally, the J = 2→1 spatial velocity map displays evidence for a decrease in velocity width towards the outer regions of the nebula; a feature which is expected of most outflow models. The J = 3→2 map also indicates the presence of a nebular extension to the north-west of the peak emission core, although this is not reproduced in the corresponding J = 1→0 map of Mufson et al. (1975)
Energetics of Domain Walls in the 2D t-J model
Using the density matrix renormalization group, we calculate the energy of a
domain wall in the 2D t-J model as a function of the linear hole density
\rho_\ell, as well as the interaction energy between walls, for J/t=0.35. Based
on these results, we conclude that the ground state always has domain walls for
dopings 0 < x < 0.3. For x < 0.125, the system has (1,0) domain walls with
\rho_\ell ~ 0.5, while for 0.125 < x < 0.17, the system has a possibly
phase-separated mixture of walls with \rho_\ell ~ 0.5 and \rho_\ell =1. For x >
0.17, there are only walls with \rho_\ell =1. For \rho_\ell = 1, diagonal (1,1)
domain walls have very nearly the same energy as (1,0) domain walls.Comment: Several minor changes. Four pages, four encapsulated figure
Study of nickel hydroxide electrodes. 2: Oxidation products of nickel (2) hydroxides
Pure phases of some oxidized Ni oxides were prepared galvanimetrically with the Ni(2) hydroxide electrode of an alkaline battery. The crystallographic data of these phases, their chemical behavior, and conditions of transition were studied
Using A Nameserver to Enhance Control System Efficiency
The Thomas Jefferson National Accelerator Facility (Jefferson Lab) control
system uses a nameserver to reduce system response time and to minimize the
impact of client name resolution on front-end computers. The control system is
based on the Experimental Physics and Industrial Control System (EPICS), which
uses name-based broadcasts to initiate data communication. By default, when
EPICS process variables (PV) are requested by client applications, all
front-end computers receive the broadcasts and perform name resolution
processing against local channel name lists. The nameserver is used to offload
the name resolution task to a single node. This processing, formerly done on
all front-end computers, is now done only by the nameserver. In a control
system with heavily loaded front-end computers and high peak client connection
loads, a significant performance improvement is seen. This paper describes the
name server in more detail, and discusses the strengths and weaknesses of
making name resolution a centralized service.Comment: ICALEPCS 200
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A high resolution millimetre and submillimetre study of W3
The continuum bolometer receiver on the James Clerk Maxwell telescope has been used to map the dense core of the star formation region W3 with a spatial resolution of 15-20 arcsec. At 350 and 800 μm, the region appears as two principal peaks around the known IR sources IRS4 and IRS5, while at 1100 μm, a further peak is noted which is interpreted as being due to free-free emission around IRS2. Taking into account the free-free contribution to the intensity, the continuum dust emission from the region is found to be consistent with optically thin emission at all of the three wavelengths considered. Values for the dust optical depth, hydrogen column density, mass, and central density have been obtained for each of the main peaks
The Leeds Winter Warmth Campaign: Stakeholder Evaluation
The winter of 2012/13 was longer and colder than usual; whilst temperatures were average in December, it was colder than usual from January through to May. March was the coldest it has been for 50 years (Met Office, 2013). This evaluation focuses on the organisations funded by the Winter Warmth campaign to deliver services to Leeds residents. The overriding aim of the evaluation was to inform the operation of possible future schemes, with good practices and any issues identified. The views of organisations on the need for the funds and how the campaign was organised were ascertained. How they delivered the services, reached clients and worked with other stakeholders is explored and their suggestions for improvements described. This report should be read alongside the overall campaign report, by Leeds City Council, and the beneficiary report
Engaging men with penile cancer in qualitative research: reflections from an interview-based study.
To explore the challenges of engaging men with penile cancer in qualitative interview research
THE IMPACT OF PENILE CANCER TREATMENT ON SEXUAL RELATIONSHIPS: A QUALITATIVE ENQUIRY
Background: Penile cancer is a rare but highly treatable condition. Current guidance recommends the use of a surgical procedure to excise the primary tumour (and a margin of normal penile tissue). Whilst treatment can be effective, treatment often has a significant impact on a patient's sexual and urinary function, and physical and mental wellbeing. The objective of this study was to explore the impact of treatment for penile cancer on sexual function and relationships. Methods: Qualitative data was collected via narrative video interviews. Maximum variation sampling was used to acquire the widest possible range of experiences. All interviews were recorded using either a digital video recorder or digital audio recorder, transcribed. A method of constant comparison analysis was used to illicit themes and outliers. Results: Twenty seven men were interviewed; mean age at diagnosis = 63 (range = 41-82); Mean number of years post-surgery = 3 (range = 0-15 years) 15 men were married, a further two were in a committed relationship, the remaining 10 were single/widowed. All men had received surgical treatment ranging from circumcision to total penectomy. Just two men had attended any form of psychological therapy. The impact of treatment varied considerably. The majority of men talked about still being able to experience arousal and sexual pleasure in some way. However, for many, penetrative sex was awkward and less gratifying than before treatment. One man who had received a total penectomy was surprised to experience a form of orgasm after surgery. For a number of men, the impact of treatment on their ability to satisfy their sexual partners was a key concern. Men who were able to openly talk with their partners about sex and the impact of the treatment on sexual practice found this a great comfort. Conclusion: The significance of sex for a man can differ considerably between individuals; relationship status, age and life stage are all likely to have a bearing on the role that sex plays in a man life. A diagnosis of cancer can also affect how a man (and his partner) views sex and the level of importance which he attaches to it. For men who are sexually active prior to treatment, surgery will undoubtedly result in changes to sexual practice, however, treatment does not have to result in sexual abstinence
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