242 research outputs found
A de Finetti representation for finite symmetric quantum states
Consider a symmetric quantum state on an n-fold product space, that is, the
state is invariant under permutations of the n subsystems. We show that,
conditioned on the outcomes of an informationally complete measurement applied
to a number of subsystems, the state in the remaining subsystems is close to
having product form. This immediately generalizes the so-called de Finetti
representation to the case of finite symmetric quantum states.Comment: 22 pages, LaTe
The effects of water addition on the threshold speed, gamma and net density of Du Pont Lino-Writ 5 direct recording paper
The effects on speed, gamma and net density of Du Pont Lino-Writ 5 paper, by the addition of water prior to the initial exposure and amplification exposure separately and in combination, was investigated. The effects on speed and net density of Kodak Polycontrast paper by water addition prior to exposure were also explored for comparsion purposes.
A statistically significant decrease in the average value of speed and a significant increase in the average value of net density was observed when Lino-Writ paper was moistened. The addition of moisture gave no evidence of having an effect on the average value of gamma. Moisture did not significantly affect either the speed or net density of Kodak Polycontrast paper
Outcome of primary percutaneous stent-revascularization in patients with atherosclerotic acute mesenteric ischemia
Background: Patients with acute mesenteric ischemia (AMI) often exhibit severe co-morbidities and significant surgical risks, leading to high perioperative morbidity. Purpose: To investigate the feasibility of primary percutaneous stent-revascularization (PPSR) in atherosclerotic AMI and its impact on patients' outcome. Material and Methods: Retrospective analysis of 19 consecutive patients (7 women, 12 men;median age, 69 years) with AMI caused by atherosclerotic, non-embolic stenoses/occlusions of the splanchnic arteries and PPSR. Alternative minimally invasive techniques were excluded. Clinical characteristics including the Charlson Comorbidity Index adjusted by age (CCIa) and symptom duration, technical and clinical success of PPSR, clinical course, 30-day mortality, and follow-up were evaluated and compared to literature data for surgical approaches. Technical success was defined as residual stenosis of 4 in 17 of 19 patients, 89%). Median symptom duration was 50 h. Technical and clinical success rates of PPSR were 95% (21 of 22 arteries) and 53% (10 of 19 patients). Seven patients underwent subsequent laparotomy with bowel resection in four cases. Thirty-day mortality was 42% (8 of 19 patients). Conclusion: In our study population of patients with atherosclerotic AMI, severe co-morbidities, prolonged acute symptoms, and significant perioperative risks PPSR of splanchnic stenoses were technically feasible and the clinical outcome was acceptable
Variability and redistribution of heat in the Atlantic Water boundary current north of Svalbard
© The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Journal of Geophysical Research: Oceans 123 (2018): 6373-6391, doi:10.1029/2018JC013814.We quantify Atlantic Water heat loss north of Svalbard using yearâlong hydrographic and current records from three moorings deployed across the Svalbard Branch of the Atlantic Water boundary current in 2012â2013. The boundary current loses annually on average 16âW mâ2 during the eastward propagation along the upper continental slope. The largest vertical fluxes of >100âW mâ2 occur episodically in autumn and early winter. Episodes of sea ice imported from the north in November 2012 and February 2013 coincided with large oceanâtoâice heat fluxes, which effectively melted the ice and sustained open water conditions in the middle of the Arctic winter. Between March and early July 2013, a persistent ice coverâmodulated airâsea fluxes. Melting sea ice at the start of the winter initiates a cold, up to 100âmâdeep halocline separating the ice cover from the warm Atlantic Water. Semidiurnal tides dominate the energy over the upper part of the slope. The vertical tidal structure depends on stratification and varies seasonally, with the potential to contribute to vertical fluxes with shearâdriven mixing. Further processes impacting the heat budget include lateral heat loss due to mesoscale eddies, and modest and negligible contributions of Ekman pumping and shelf break upwelling, respectively. The continental slope north of Svalbard is a key example regarding the role of ocean heat for the sea ice cover. Our study underlines the complexity of the ocean's heat budget that is sensitive to the balance between oceanic heat advection, vertical fluxes, airâsea interaction, and the sea ice cover.Arctic Ocean program at the FRAM-High North Research Centre for Climate and the environment;
National Science Foundation (NSF) Grant Number: ARC-1264098;
Polish-Norwegian Research Programme Grant Number: POL-NOR/202006/10/2013;
Research Council of Norway Grant Number: 276730;
Steven Grossman Family Foundatio
Recommended from our members
Evolutionary biology for the 21st century
New theoretical and conceptual frameworks are required for evolutionary biology to capitalize on the wealth of data now becoming available from the study of genomes, phenotypes, and organisms - including humans - in their natural environments.Molecular and Cellular BiologyOrganismic and Evolutionary Biolog
The Atlantic Water boundary current north of Svalbard in late summer
Author Posting. © American Geophysical Union, 2017. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 122 (2017): 2269â2290, doi:10.1002/2016JC012486.Data from a shipboard hydrographic/velocity survey carried out in September 2013 of the region north of Svalbard in the Nansen Basin are analyzed to characterize the Atlantic Water (AW) boundary current as it flows eastward along the continental slope. Eight meridional transects across the current, spanning an alongstream distance of 180 km, allow for a detailed description of the current and the regional water masses. During the survey the winds were light and there was no pack-ice. The mean section reveals that the boundary current was O(40 km) wide, surface-intensified, with a maximum velocity of 20 cm/s. Its mean transport during the survey was 3.11â±â0.33 Sv, of which 2.31â±â0.29 Sv was AW. This suggests that the two branches of AW entering the Arctic Ocean via Fram Straitâthe Yermak Plateau branch and the Svalbard branchâhave largely combined into a single current by 30°E. At this location the boundary current meanders with a systematic change in its kinematic structure during offshore excursions. A potential vorticity analysis indicates that the flow is baroclinically unstable, consistent with previous observations of AW anticyclones offshore of the current as well as the presence of a near-field cyclone in this data set. Our survey indicates that only a small portion of the boundary current is diverted into the KvitĂžya Trough (0.17â±â0.08 Sv) and that the AW temperature/salinity signal is quickly eroded within the trough.National Science Foundation Grant Number: ARC-12640982017-09-2
One-and-a-half quantum de Finetti theorems
We prove a new kind of quantum de Finetti theorem for representations of the
unitary group U(d). Consider a pure state that lies in the irreducible
representation U_{mu+nu} for Young diagrams mu and nu. U_{mu+nu} is contained
in the tensor product of U_mu and U_nu; let xi be the state obtained by tracing
out U_nu. We show that xi is close to a convex combination of states Uv, where
U is in U(d) and v is the highest weight vector in U_mu. When U_{mu+nu} is the
symmetric representation, this yields the conventional quantum de Finetti
theorem for symmetric states, and our method of proof gives near-optimal bounds
for the approximation of xi by a convex combination of product states. For the
class of symmetric Werner states, we give a second de Finetti-style theorem
(our 'half' theorem); the de Finetti-approximation in this case takes a
particularly simple form, involving only product states with a fixed spectrum.
Our proof uses purely group theoretic methods, and makes a link with the
shifted Schur functions. It also provides some useful examples, and gives some
insight into the structure of the set of convex combinations of product states.Comment: 14 pages, 3 figures, v4: minor additions (including figures),
published versio
A Self-Consistent Microscopic Theory of Surface Superconductivity
The electronic structure of the superconducting surface sheath in a type-II
superconductor in magnetic fields is calculated
self-consistently using the Bogoliubov-de Gennes equations. We find that the
pair potential exhibits pronounced Friedel oscillations near the
surface, in marked contrast with the results of Ginzburg-Landau theory. The
role of magnetic edge states is emphasized. The local density of states near
the surface shows a significant depletion near the Fermi energy due to the
development of local superconducting order. We suggest that this structure
could be unveiled by scanning-tunneling microscopy studies performed near the
edge of a superconducting sample.Comment: 12 pages, Revtex 3.0, 3 postscript figures appende
Structure, transport, and seasonality of the Atlantic Water boundary current north of Svalbard: Results from a yearlong mooring array
Author Posting. © American Geophysical Union, 2019. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research-Oceans 124(3), (2019): 1679-1698, doi:10.1029/2018JC014759.The characteristics and seasonality of the Svalbard branch of the Atlantic Water (AW) boundary current in the Eurasian Basin are investigated using data from a sixâmooring array deployed near 30°E between September 2012 and September 2013. The instrument coverage extended to 1,200âm depth and approximately 50 km offshore of the shelf break, which laterally bracketed the flow. Averaged over the year, the transport of the current over this depth range was 3.96 ± 0.32 Sv (1 Sv = 106 m3/s). The transport within the AW layer was 2.08 ± 0.24 Sv. The current was typically subsurface intensified, and its dominant variability was associated with pulsing rather than meandering. From late summer to early winter the AW was warmest and saltiest, and its eastward transport was strongest (2.44 ± 0.12 Sv), while from midspring to midsummer the AW was coldest and freshest and its transport was weakest (1.10 ± 0.06 Sv). Deep mixed layers developed through the winter, extending to 400â to 500âm depth in early spring until the pack ice encroached the area from the north shutting off the airâsea buoyancy forcing. This vertical mixing modified a significant portion of the AW layer, suggesting that, as the ice cover continues to decrease in the southern Eurasian Basin, the AW will be more extensively transformed via local ventilation.We are grateful to the crew of the R/V Lance for the collection of the data. The U.S. component of AâTWAIN was funded by the National Science Foundation under grant ARCâ1264098 as well as a grant from the Steven Grossman Family Foundation. The Norwegian component of AâTWAIN was funded by the âArctic Oceanâ flagship program at the Fram Centre. The data used in this study are available at http://atwain.whoi.edu and data.npolar.no (Sundfjord et al., 2017). The data from Fram Strait are available at https://doi.pangaea.de/10.1594/PANGAEA.8539022019-08-1
Emisari: a management information system designed to aid and involve people
The EMISARI System described in this paper represents a major departure from conventional MIS design. It is oriented not toward data per se, but rather toward activities of the people who generate and use the data. Thus it provides not merely for reporting up the chain of command, but also for dissemination of policy guidance and reference material down the chain, and for lateral communication among all users. It places a premium upon flexibility, to permit rapid system modifications in response to changes in user functions and needs and it offers a greatly simplified operation, to avoid any necessity for extensive user training or complex operation manuals. The overall approach may be viewed as a greatly modernized version of the classic telephone party line, using a computer to organize, selectively sort, and store-and-forward a constant flow of statistics, messages, estimates, reference materials, guidelines, notices, and other informational accountrements of a modern management operation
- âŠ