667 research outputs found
Preroughening, Diffusion, and Growth of An FCC(111) Surface
Preroughening of close-packed fcc(111) surfaces, found in rare gas solids, is
an interesting, but poorly characterized phase transition. We introduce a
restricted solid-on-solid model, named FCSOS, which describes it. Using mostly
Monte Carlo, we study both statics, including critical behavior and scattering
properties, and dynamics, including surface diffusion and growth. In antiphase
scattering, it is shown that preroughening will generally show up at most as a
dip. Surface growth is predicted to be continuous at preroughening, where
surface self-diffusion should also drop. The physical mechanism leading to
preroughening on rare gas surfaces is analysed, and identified in the step-step
elastic repulsion.Comment: Revtex + uuencoded figures, to appear in Physical Review Letter
Sequential drain amylase to guide drain removal following pancreatectomy
BACKGROUND:
Although used as criterion for early drain removal, postoperative day (POD) 1 drain fluid amylase (DFA) ≤ 5000 U/L has low negative predictive value for clinically relevant postoperative pancreatic fistula (CR-POPF). It was hypothesized that POD3 DFA ≤ 350 could provide further information to guide early drain removal.
METHODS:
Data from a pancreas surgery consortium database for pancreatoduodenectomy and distal pancreatectomy patients were analyzed retrospectively. Those patients without drains or POD 1 and 3 DFA data were excluded. Patients with POD1 DFA ≤ 5000 were divided into groups based on POD3 DFA: Group A (≤350) and Group B (>350). Operative characteristics and 60-day outcomes were compared using chi-square test.
RESULTS:
Among 687 patients in the database, all data were available for 380. Fifty-five (14.5%) had a POD1 DFA > 5000. Among 325 with POD1 DFA ≤ 5000, 254 (78.2%) were in Group A and 71 (21.8%) in Group B. Complications (35 (49.3%) vs 87 (34.4%); p = 0.021) and CR-POPF (13 (18.3%) vs 10 (3.9%); p < 0.001) were more frequent in Group B.
CONCLUSIONS:
In patients with POD1 DFA ≤ 5000, POD3 DFA ≤ 350 may be a practical test to guide safe early drain removal. Further prospective testing may be useful
Guidelines for Perioperative Care for Liver Surgery: Enhanced Recovery After Surgery (ERAS) Society Recommendations 2022.
Enhanced Recovery After Surgery (ERAS) has been widely applied in liver surgery since the publication of the first ERAS guidelines in 2016. The aim of the present article was to update the ERAS guidelines in liver surgery using a modified Delphi method based on a systematic review of the literature.
A systematic literature review was performed using MEDLINE/PubMed, Embase, and the Cochrane Library. A modified Delphi method including 15 international experts was used. Consensus was judged to be reached when >80% of the experts agreed on the recommended items. Recommendations were based on the Grading of Recommendations, Assessment, Development and Evaluations system.
A total of 7541 manuscripts were screened, and 240 articles were finally included. Twenty-five recommendation items were elaborated. All of them obtained consensus (>80% agreement) after 3 Delphi rounds. Nine items (36%) had a high level of evidence and 16 (64%) a strong recommendation grade. Compared to the first ERAS guidelines published, 3 novel items were introduced: prehabilitation in high-risk patients, preoperative biliary drainage in cholestatic liver, and preoperative smoking and alcohol cessation at least 4 weeks before hepatectomy.
These guidelines based on the best available evidence allow standardization of the perioperative management of patients undergoing liver surgery. Specific studies on hepatectomy in cirrhotic patients following an ERAS program are still needed
Muon-spin rotation and magnetization studies of chemical and hydrostatic pressure effects in EuFe_{2}(As_{1-x}P_{x})_{2}
The magnetic phase diagram of EuFe(AsP) was
investigated by means of magnetization and muon-spin rotation studies as a
function of chemical (isovalent substitution of As by P) and hydrostatic
pressure. The magnetic phase diagrams of the magnetic ordering of the Eu and Fe
spins with respect to P content and hydrostatic pressure are determined and
discussed. The present investigations reveal that the magnetic coupling between
the Eu and the Fe sublattices strongly depends on chemical and hydrostatic
pressure. It is found that chemical and hydrostatic pressure have a similar
effect on the Eu and Fe magnetic order.Comment: 11 pages, 10 figure
Pseudogap formation of four-layer BaRuO and its electrodynamic response changes
We investiaged the optical properties of four-layer BaRuO, which shows
a fermi-liquid-like behavior at low temperature. Its optical conductivity
spectra clearly displayed the formation of a pseudogap and the development of a
coherent peak with decreasing temperature. Temperature-dependences of the
density and the scattering rate of the coherent component were
also derived. As the temperature decreases, both and decrease for
four-layer BaRuO. These electrodynamic responses were compared with those
of nine-layer BaRuO, which also shows a pseudogap formation but has an
insulator-like state at low temperature. It was found that the relative rates
of change of both and determine either metallic or insulator-like
responses in the ruthenates. The optical properties of the four-layer ruthenate
were also compared with those of other pseudogap systems, such as high
cuprates and heavy electron systems.Comment: 7 figures. submitted to Phys. Rev.
Constraints on Large Extra Dimensions with Bulk Neutrinos
We consider right-handed neutrinos propagating in (large) extra
dimensions, whose only coupling to Standard Model fields is the Yukawa coupling
to the left-handed neutrino and the Higgs boson. These theories are attractive
as they can explain the smallness of the neutrino mass, as has already been
shown. We show that if is bigger than two, there are strong
constraints on the radius of the extra dimensions, resulting from the
experimental limit on the probability of an active state to mix into the large
number of sterile Kaluza-Klein states of the bulk neutrino. We also calculate
the bounds on the radius resulting from requiring that perturbative unitarity
be valid in the theory, in an imagined Higgs-Higgs scattering channel.Comment: 24 pages, 4 figures, revtex4. v2: Minor typos corrected, references
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Multipartite entangled states in coupled quantum dots and cavity-QED
We investigate the generation of multipartite entangled state in a system of
N quantum dots embedded in a microcavity and examine the emergence of genuine
multipartite entanglement by three different characterizations of entanglement.
At certain times of dynamical evolution one can generate multipartite entangled
coherent exciton states or multiqubit states by initially preparing the
cavity field in a superposition of coherent states or the Fock state with one
photon, respectively. Finally we study environmental effects on multipartite
entanglement generation and find that the decay rate for the entanglement is
proportional to the number of excitons.Comment: 9 pages, 4 figures, to appear in Phys. Rev.
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