Curvature as an external field in mechanical antiferromagnets

A puckered sheet is a freestanding crystalline membrane with an embedded array of bistable buckled units. Recent work has shown that the bistable units behave like spins in a two-dimensional compressible Ising antiferromagnet with, however, a coupling to flexural phonons. At finite temperature, this purely mechanical system displays Ising-like phase transitions, which drive anomalous thermal expansion. Here, we show that geometry can be used to control phase behavior: curvature produces a radius-dependent "external field" that encourages alignment between neighboring "spins," disrupting the ordered checkerboard ground state of anti-aligned neighbors. The effective field strength scales as the inverse of the radius of curvature. We identify this effective field theoretically with both a discrete real space model and a nonlinear continuum elastic model. We then present molecular dynamics simulations of puckered sheets in cylindrical geometries at zero and finite temperature, probing the influence of curvature on the stability of configurations and phase transitions. Our work demonstrates how curvature and temperature can be used to design and operate a responsive and tunable metamaterial at either the macroscale or nanoscale.Comment: 19 pages, 10 figure

Direct extraction of the Eliashberg function for electron-phonon coupling: A case study of Be(1010)

We propose a systematic procedure to directly extract the Eliashberg function for electron-phonon coupling from high-resolution angle-resolved photoemission data. The procedure is successfully applied to the Be(1010) surface, providing new insights to electron-phonon coupling at this surface. The method is shown to be robust against imperfections in experimental data and suitable for wider applications.Comment: 4 pages, 4 figures. More details concerning the procedure are include

Direct Determination of Electron-Phonon Coupling Matrix Element in a Correlated System

High-resolution electron energy loss spectroscopy measurements have been carried out on an optimally doped cuprate Bi2Sr2CaCu2O8+{\delta}. The momentum-dependent linewidth and the dispersion of an A1 optical phonon are obtained. Based on these data as well as the detailed knowledge of the electronic structure from angle-resolved photoemission spectroscopy, we develop a scheme to determine the full structure of electron-phonon coupling for a specific phonon mode, thus providing a general method for directly resolving the EPC matrix element in systems with anisotropic electronic structures

Multiple Bosonic Mode Coupling in Electron Self-Energy of (La_2-xSr_x)CuO_4

High resolution angle-resolved photoemission spectroscopy data along the (0,0)-($\pi$,$\pi$) nodal direction with significantly improved statistics reveal fine structure in the electron self-energy of the underdoped (La$_{2-x}$Sr$_x$)CuO$_4$ samples in the normal state. Fine structure at energies of (40$\sim$46) meV and (58$\sim$63)meV, and possible fine structure at energies of (23$\sim$29)meV and (75$\sim$85)meV, have been identified. These observations indicate that, in LSCO, more than one bosonic modes are involved in the coupling with electrons.Comment: 4 pages, 3 figures, Fig. 2 update

Bovid ecomorphology and hominin paleoenvironments of the Shungura Formation, lower Omo River Valley, Ethiopia.

The Shungura Formation in the lower Omo River Valley, southern Ethiopia, has yielded an important paleontological and archeological record from the Pliocene and Pleistocene of eastern Africa. Fossils are common throughout the sequence and provide evidence of paleoenvironments and environmental change through time. This study developed discriminant function ecomorphology models that linked astragalus morphology to broadly defined habitat categories (open, light cover, heavy cover, forest, and wetlands) using modern bovids of known ecology. These models used seven variables suitable for use on fragmentary fossils and had overall classification success rates of >82%. Four hundred and one fossils were analyzed from Shungura Formation members B through G (3.4-1.9 million years ago). Analysis by member documented the full range of ecomorph categories, demonstrating that a wide range of habitats existed along the axis of the paleo-Omo River. Heavy cover ecomorphs, reflecting habitats such as woodland and heavy bushland, were the most common in the fossil sample. The trend of increasing open cover habitats from Members C through F suggested by other paleoenvironmental proxies was documented by the increase in open habitat ecomorphs during this interval. However, finer grained analysis demonstrated considerable variability in ecomorph frequencies over time, suggesting that substantial short-term variability is masked when grouping samples by member. The hominin genera Australopithecus, Homo, and Paranthropus are associated with a range of ecomorphs, indicating that all three genera were living in temporally variable and heterogeneous landscapes. Australopithecus finds were predominantly associated with lower frequencies of open habitat ecomorphs, and high frequencies of heavy cover ecomorphs, perhaps indicating a more woodland focus for this genus

A randomised controlled study shows supplementation of overweight and obese adults with lactobacilli and bifidobacteria reduces bodyweight and improves well-being

In an exploratory, block-randomised, parallel, double-blind, single-centre, placebo-controlled superiority study (ISRCTN12562026, funded by Cultech Ltd), 220 Bulgarian participants (30 to 65 years old) with BMI 25–34.9 kg/m2 received Lab4P probiotic (50 billion/day) or a matched placebo for 6 months. Participants maintained their normal diet and lifestyle. Primary outcomes were changes in body weight, BMI, waist circumference (WC), waist-to-height ratio (WtHR), blood pressure and plasma lipids. Secondary outcomes were changes in plasma C-reactive protein (CRP), the diversity of the faecal microbiota, quality of life (QoL) assessments and the incidence of upper respiratory tract infection (URTI). Significant between group decreases in body weight (1.3 kg, p < 0.0001), BMI (0.045 kg/m2, p < 0.0001), WC (0.94 cm, p < 0.0001) and WtHR (0.006, p < 0.0001) were in favour of the probiotic. Stratification identified greater body weight reductions in overweight subjects (1.88%, p < 0.0001) and in females (1.62%, p = 0.0005). Greatest weight losses were among probiotic hypercholesterolaemic participants (−2.5%, p < 0.0001) alongside a significant between group reduction in small dense LDL-cholesterol (0.2 mmol/L, p = 0.0241). Improvements in QoL and the incidence rate ratio of URTI (0.60, p < 0.0001) were recorded for the probiotic group. No adverse events were recorded. Six months supplementation with Lab4P probiotic resulted in significant weight reduction and improved small dense low-density lipoprotein-cholesterol (sdLDL-C) profiles, QoL and URTI incidence outcomes in overweight/obese individuals

Propofol cardioplegia: A single-center, placebo-controlled, randomized controlled trial

OBJECTIVES: Cardiac surgery with cardiopulmonary bypass and cardioplegic arrest is an effective treatment for coronary artery and aortic valve diseases. However, the myocardium sustains reperfusion injury after ischemic cardioplegic arrest. Our objective was to assess the benefits of supplementing cardioplegia solution with the general anesthetic propofol in patients undergoing either coronary artery bypass grafting (CABG) or aortic valve replacement (AVR). METHODS: A single-center, double-blind randomized controlled trial was carried out to compare cardioplegia solution supplemented with propofol (concentration 6 μg/mL) versus intralipid (placebo). The primary outcome was cardiac troponin T release over the first 48 hours after surgery. RESULTS: We recruited 101 participants (51 in the propofol group, 50 in the intralipid group); 61 underwent CABG and 40 underwent AVR. All participants were followed to 3 months. Cardiac troponin T release was on average 15% lower with propofol supplementation (geometric mean ratio, 0.85; 95% confidence interval [CI], 0.73-1.01; P = .051). There were no differences for CABG participants but propofol-supplemented participants undergoing AVR had poorer postoperative renal function (geometric mean ratio, 1.071; 95% CI, 1.019-1.125; P = .007), with a trend toward longer intensive care stay (median, 89.5 vs 47.0 hours; hazard ratio, 0.58; 95% CI, 0.31-1.09; P = .09) and fewer with perfect health (based on the EQ-5D health utility index) at 3 months (odds ratio, 0.26; 95% CI, 0.06-1.05; P = .058) compared with the intralipid group. Safety profiles were similar. There were no deaths. CONCLUSIONS: Propofol supplementation in cardioplegia appears to be cardioprotective. Its influence on early clinical outcomes may differ between CABG and AVR surgery. A larger, multicenter study is needed to confirm or refute these suggestions