Phase diagram of the fully frustrated transverse-field Ising model on the honeycomb lattice

Motivated by the current interest in the quantum dimer model on the triangular lattice, we investigate the phase diagram of the closely related fully-frustrated transverse field Ising model on the honeycomb lattice using classical and semi-classical approximations. We show that, in addition to the fully polarized phase at large field, the classical model possesses a multitude of phases that break the translational symmetry which in the dimer language, correspond to a plaquette phase and a columnar phase separated by an infinite cascade of mixed phases. The modification of the phase diagram by quantum fluctuations has been investigated in the context of linear spin-wave theory. The extrapolation of the semiclassical energies suggests that the plaquette phase extends down to zero field for spin 1/2, in agreement with the $\sqrt{12}\times\sqrt{12}$ phase of the quantum dimer model on the triangular lattice with only kinetic energy.Comment: 15 Pages, 11 Figures, Accepted for PR

Dynamical structure factors and excitation modes of the bilayer Heisenberg model

Using quantum Monte Carlo simulations along with higher-order spin-wave theory, bond-operator and strong-coupling expansions, we analyse the dynamical spin structure factor of the spin-half Heisenberg model on the square-lattice bilayer. We identify distinct contributions from the low-energy Goldstone modes in the magnetically ordered phase and the gapped triplon modes in the quantum disordered phase. In the antisymmetric (with respect to layer inversion) channel, the dynamical spin structure factor exhibits a continuous evolution of spectral features across the quantum phase transition, connecting the two types of modes. Instead, in the symmetric channel we find a depletion of the spectral weight when moving from the ordered to the disordered phase. While the dynamical spin structure factor does not exhibit a well-defined distinct contribution from the amplitude (or Higgs) mode in the ordered phase, we identify an only marginally-damped amplitude mode in the dynamical singlet structure factor, obtained from interlayer bond correlations, in the vicinity of the quantum critical point. These findings provide quantitative information in direct relation to possible neutron or light scattering experiments in a fundamental two-dimensional quantum-critical spin system.Comment: 19 pages, 15 figure

Evidence of columnar order in the fully frustrated transverse field Ising model on the square lattice

Using extensive classical and quantum Monte Carlo simulations, we investigate the ground-state phase diagram of the fully frustrated transverse field Ising model on the square lattice. We show that pure columnar order develops in the low-field phase above a surprisingly large length scale, below which an effective U(1) symmetry is present. The same conclusion applies to the Quantum Dimer Model with purely kinetic energy, to which the model reduces in the zero-field limit, as well as to the stacked classical version of the model. By contrast, the 2D classical version of the model is shown to develop plaquette order. Semiclassical arguments show that the transition from plaquette to columnar order is a consequence of quantum fluctuations.Comment: 5 pages (including Supplemental Material), 5 figure

Current surgical concepts and indications in the management of the short bowel state: A call for the use of multidisciplinary intestinal rehabilitation programs

The mainstay of management for short bowel syndrome (SBS) is to promote access to the best quality of care provided by the intestinal rehabilitation program (IRP) in specialized centres. When treating SBS patients, the main goal is to minimize disease-associated complications, as well as achieve enteral autonomy. Surgical strategies should be selected cautiously upon the actual state of the bowel with respect to what it is clinically relevant for that specific patient. To this aim, a personalized and multidisciplinary approach for such a complex syndrome is needed

‘Malvasia nera di Brindisi/Lecce’ grapevine cultivar (Vitis vinifera L.) originated from ‘Negroamaro’ and ‘Malvasia bianca lunga’

‘Malvasia nera di Brindisi’ and ‘Malvasia nera di Lecce’ are two of the few Malvasias with black berries and belong to the Apulian ampelographic assortment (South Italy). Their presumed synonymy has been recently ascertained with SSR markers and therefore these two black 'Malvasias' can be considered as an unique variety. We discovered that this cultivar is the cross between ‘Malvasia bianca lunga’ alias ‘Malvasia del Chianti’ and ‘Negroamaro’ by using 42 nuclear SSR. Both parents belong to the Apulian varietal resources, since centuries. So far, ‘Malvasia nera di Brindisi/Lecce’ origin has been obscure; now we may assert that this cultivar was born right in Apulia. Three sets of chloroplast SSR loci were used to determine the female and the male parent: 6 ccmp loci, already used in previous pedigree studies, 15 ccSSR loci and 2 NTCP loci, derived from tobacco. The second set of loci was sequenced in order to compare the length of the markers with the reference species where they were originally obtained: in 4 cases no microsatellite motives were detected and in other 4 cases the perfect repetition found in tobacco was not maintained in grape. Unfortunately, the three sets of markers failed to show any polymorphism. A detailed comparison of the black Malvasia morphology with its two parents showed a closer similarity to ‘Negroamaro’. Also the anthocyanin profile is in agreement with that of the black parent; its varietal aroma presents interesting levels of free and bound 2-phenylethanol, responsible for rose flavor, and of bound linalool compounds.

Deep Sequencing Analysis of RNAs from Citrus Plants Grown in a Citrus Sudden Death-Affected Area Reveals Diverse Known and Putative Novel Viruses.

Citrus sudden death (CSD) has caused the death of approximately four million orange trees in a very important citrus region in Brazil. Although its etiology is still not completely clear, symptoms and distribution of affected plants indicate a viral disease. In a search for viruses associated with CSD, we have performed a comparative high-throughput sequencing analysis of the transcriptome and small RNAs from CSD-symptomatic and -asymptomatic plants using the Illumina platform. The data revealed mixed infections that included Citrus tristeza virus (CTV) as the most predominant virus, followed by the Citrus sudden death-associated virus (CSDaV), Citrus endogenous pararetrovirus (CitPRV) and two putative novel viruses tentatively named Citrus jingmen-like virus (CJLV), and Citrus virga-like virus (CVLV). The deep sequencing analyses were sensitive enough to differentiate two genotypes of both viruses previously associated with CSD-affected plants: CTV and CSDaV. Our data also showed a putative association of the CSD-symptomatic plants with a specific CSDaV genotype and a likely association with CitPRV as well, whereas the two putative novel viruses showed to be more associated with CSD-asymptomatic plants. This is the first high-throughput sequencing-based study of the viral sequences present in CSD-affected citrus plants, and generated valuable information for further CSD studies

On-chip production of nanometer sized 'Ultra fine' bubble populations

Microbubble (MB) contrast agents have been used for many years as image enhancers for medical Ultrasound (US). Ultra-Fine bubble (UFB) populations of bubbles <1 µm in diameter are a relatively new technology that has found use as highly effective ‘eco’ cleaning agents. High-resolution US imaging is another potentially exciting area for UFB. This paper reports the on-chip production of UFB populations with a diameter of ~ 500 – 700 nm at a concentration of 10¹⁰ bub / mL. These UFB showed US scattering at higher frequency fields and enhanced contrast when imaging in in vivo mouse models

Membrane cholesterol modulates LOX-1 shedding in endothelial cells

The lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is a scavenger receptor responsible for ox-LDL recognition, binding and internalization, which is up-regulated during atherogenesis. Its activation triggers endothelium dysfunction and induces inflammation. A soluble form of LOX-1 has been identified in the human blood and its presence considered a biomarker of cardiovascular diseases. We recently showed that cholesterol-lowering drugs inhibit ox-LDL binding and internalization, rescuing the ox-LDL induced apoptotic phenotype in primary endothelial cells. Here we have investigated the molecular bases of human LOX-1 shedding by metalloproteinases and the role of cell membrane cholesterol on the regulation of this event by modulating its level with MβCD and statins. We report that membrane cholesterol affects the release of different forms of LOX-1 in cells transiently and stably expressing human LOX-1 and in a human endothelial cell line (EA.hy926). In particular, our data show that i) cholesterol depletion triggers the release of LOX-1 in exosomes as a full-length transmembrane isoform and as a truncated ectodomain soluble fragment (sLOX-1); ii) endothelial cells secrete a soluble metalloproteinase which induces LOX-1 ectodomain shedding and iii) long term statins treatment enhances sLOX-1 proteolytic shedding

Plasticised regenerated silk/gold nanorods hybrids as sealant and bio-piezoelectric materials

Manual and mechanical suturing are currently the gold standard for bowel anastomosis. If tissue approximation fails, anastomotic leaks occur. Anastomotic leaks may have catastrophic consequences. The development of a fully absorbable, biocompatible sealant material based on a bio-ink silk fibroin can reduce the chance of anastomotic leaks. We have produced a Ca-modified plasticised regenerated silk (RS) with gold nanorods sealant. This sealant was applied to anastomosed porcine intestine. Water absorption from wet tissue substrate applied compressive strains on hybrid RS films. This compression results in a sealant effect on anastomosis. The increased toughness of the hybrid plasticised RS resulted in the designing of a bio-film with superior elongation at break (i.e., &asymp;200%) and bursting pressure. We have also reported structure-dependent piezoelectricity of the RS film that shows a piezoelectric effect out of the plane. We hope that in the future, bowel anastomosis can be simplified by providing a multifunctional bio-film that makes feasible the mechanical tissue joint without the need for specific tools and could be used in piezoelectric sealant heads