Ground state features of the Frohlich model

Following the ideas behind the Feynman approach, a variational wave function is proposed for the Fr\"ohlich model. It is shown that it provides, for any value of the electron-phonon coupling constant, an estimate of the polaron ground state energy better than the Feynman method based on path integrals. The mean number of phonons, the average electronic kinetic and interaction energies, the ground state spectral weight and the electron-lattice correlation function are calculated and successfully compared with the best available results.Comment: 6 figure

A neurodevelopment approach for a transitional model of early onset schizophrenia

In the last decades, the conceptualization of schizophrenia has dramatically changed, moving from a neurodegenerative process occurring in early adult life to a neurodevelopmental disorder starting be-fore birth, showing a variety of premorbid and prodromal symptoms and, in relatively few cases, evolving in the full-blown psychotic syndrome. High rates of co-occurring different neurodevelopmental disorders such as Autism spectrum disorder and ADHD, predating the onset of SCZ, and neurobio-logical underpinning with significant similarities, support the notion of a pan-developmental disturbance consisting of impairments in neuromotor, receptive language, social and cognitive development. Con-sidering that many SCZ risk factors may be similar to symptoms of other neurodevelopmental psychi-atric disorders, transition processes from child & adolescent to adult systems of care should include both high risk people as well as subject with other neurodevelopmental psychiatric disorders with different levels of severity. This descriptive mini-review discuss the need of innovative clinical approaches, re-considering specific diagnostic categories, stimulating a careful analysis of risk factors and promoting the appropriate use of new and safer medications

Design, synthesis and biological activity of selective hCAs inhibitors based on 2-(benzylsulfinyl)benzoic acid scaffold

A large library of derivatives based on the scaffold of 2-(benzylsulfinyl)benzoic acid were synthesised and tested as atypical inhibitors against four different isoforms of human carbonic anhydrase (hCA I, II, IX and XII, EC 4.2.1.1). The exploration of the chemical space around the main functional groups led to the discovery of selective hCA IX inhibitors in the micromolar/nanomolar range, thus establishing robust structure-activity relationships within this versatile scaffold. HPLC separation of some selected chiral compounds and biological evaluation of the corresponding enantiomers was performed along with molecular modelling studies on the most active derivatives

Sharp transition for single polarons in the one-dimensional Su-Schrieffer-Heeger model

We study a single polaron in the Su-Schrieffer-Heeger (SSH) model using four different techniques (three numerical and one analytical). Polarons show a smooth crossover from weak to strong coupling, as a function of the electron-phonon coupling strength $\lambda$, in all models where this coupling depends only on phonon momentum $q$. In the SSH model the coupling also depends on the electron momentum $k$; we find it has a sharp transition, at a critical coupling strength $\lambda_c$, between states with zero and nonzero momentum of the ground state. All other properties of the polaron are also singular at $\lambda = \lambda_c$, except the average number of phonons in the polaronic cloud. This result is representative of all polarons with coupling depending on $k$ and $q$, and will have important experimental consequences (eg., in ARPES and conductivity experiments)

Unusual sub-genus associations of fecal Prevotella and Bacteroides with specific dietary patterns

Background: Diet has a recognized effect in shaping gut microbiota. Many studies link an increase in Prevotella to high-fibre diet, while Bacteroides abundance is usually associated with the consumption of animal fat and protein-rich diets. Nevertheless, closely related species and strains may harbour different genetic pools; therefore, further studies should aim to understand whether species of the same genus are consistently linked to dietary patterns or equally responsive to diet variations. Here, we used oligotyping of 16S rRNA gene sequencing data to exploit the diversity within Prevotella and Bacteroides genera in faecal samples of omnivore and non-omnivore subjects from a previously studied cohort. Results: A great heterogeneity was found in oligotype composition. Nevertheless, different oligotypes within the same genus showed distinctive correlation patterns with dietary components and metabolome. We found that some Prevotella oligotypes are significantly associated with the plant-based diet but some are associated with animal-based nutrients, and the same applies to Bacteroides. Therefore, an indiscriminate association of Bacteroidetes genera with specific dietary patterns may lead to an oversimplified vision that does not take into account sub-genus diversity and the different possible responses to dietary components. Conclusions: We demonstrated that Prevotella and Bacteroides oligotypes show distinctive correlation patterns with dietary components and metabolome. These results substantiate a current oversimplification of diet-dependent microbe-host associations and highlighted that sub-genus differences must be taken into account when planning gut microbiota modulation for health benefits

Spin polarization of electrons with Rashba double-refraction

We demonstrate how the Rashba spin-orbit coupling in semiconductor heterostructures can produce and control a spin-polarized current without ferromagnetic leads. Key idea is to use spin-double refraction of an electronic beam with a nonzero incidence angle. A region where the spin-orbit coupling is present separates the source and the drain without spin-orbit coupling. We show how the transmission and the beam spin-polarization critically depend on the incidence angle. The transmission halves when the incidence angle is greater than a limit angle and a significant spin-polarization appears. Increasing the spin-orbit coupling one can obtain the modulation of the intensity and of the spin-polarization of the output electronic current when the input current is unpolarized. Our analysis shows the possibility to realize a spin-field-effect transistor based on the propagation of only one mode with the region with spin-orbit coupling. Where the original Datta and Das device [Appl.Phys.Lett. {\bf 56}, 665 (1990)] use the spin-precession that originates from the interference between two modes with orthogonal spin.Comment: 12 pages with 7 figure

Polaron features for long-range electron-phonon interaction

The polaron features for long-range electron-phonon interaction are investigated by extending a variational approach previously proposed for the study of systems with local coupling. The ground-state spectral weight, the average kinetic energy, the mean number of phonons, and the electron-lattice correlation function are discussed for a wide range of model parameters focusing on the adiabatic regime and comparing the results with the short-range case (Holstein model). A strong mixing of electronic and phononic degrees of freedom for small values of the electron-phonon coupling constant is found in the adiabatic case due to the long-range interaction. Finally a polaron "phase diagram" is proposed.Comment: 4 figs., to appear in J. Phys.:Condens. Matte

Physical therapy for benign positional vertigo of posterior canal: the role of alternated Epley and Semont maneuvers.

Objective: To investigate if alternated Epley (EP) and Semont (ST) maneuvers could be more effective than repetition of the same in benign paroxysmal positional vertigo of posterior semicircular canal (pBPPV). Design: We retrospectively reviewed the outcome of pBPPV patients treated with a second maneuver for the persistence of positional nystagmus. Study Sample: Forty-seven patients underwent 2 STs, 64 with 2 EPs, and 71 EPs followed by ST. Videonystagmography and Dizziness Handicap Inventory (DHI) questionnaire were performed. Results: Absence of positional nystagmus was achieved after 2 maneuvers in 136 patients with pBPPV: 65.9% in the ST group, 70.3% in the EP group, and 84.5% in the EP-ST group. Alternated EP and ST were significantly more effective than repeated ST (P = .03), while we found no significant difference when compared with repeated EP (P = .07). At 1-month follow-up, 12 patients showed persistent positional nystagmus without difference between groups. After 1 month, the 46 patients with negative outcome had significantly higher DHI values (P = .01) than other 136 patients with pBPPV. Conclusions: Alternated EP and ST seemed more effective than repeating the same maneuver in treating pBPPV, and this should be confirmed in prospective clinical studies. Resolution of nystagmus after maneuvers was fundamental to reduce handicap deriving from dizziness as reported in DHI

Interplay between charge-lattice interaction and strong electron correlations in cuprates: phonon anomaly and spectral kinks

We investigate the interplay between strong electron correlations and charge-lattice interaction in cuprates. The coupling between half breathing bond stretching phonons and doped holes in the t-t'-J model is studied by limited phonon basis exact diagonalization method. Nonadiabatic electron-phonon interaction leads to the splitting of the phonon spectral function at half-way to the zone boundary at $\vec{q}_s=\{(\pm \pi / 2, 0), (0, \pm \pi / 2) \}$ and to low energy kink feature in the electron dispersion, in agreement with experimental observations. Another kink due to strong electron correlation effects is observed at higher energy, depending on the strength of the charge-lattice coupling.Comment: 4 pages, 3 figure

Environmental microbiome mapping as a strategy to improve quality and safety in the food industry

In food industries, an environmentally-adapted microbiome can colonize the surfaces of equipment and tools and be transferred to the food product or intermediates of production. These complex microbial consortia may include microbial spoilers, pathogens, as well as beneficial microbes. Advances in sequencing technologies and metagenomics provide the opportunity to map the environmental microbiome in food industries at an unprecedented depth, highlighting the importance of the resident microbial communities in influencing food quality and safety, as well as the main factors shaping its composition and activities. However, specific technical issues must be considered. Although microbiome mapping in the food industry has the potential to revolutionize food safety and quality management systems, its application as routine practice is still challenging and technical issues limit the exploitation of the powerful information that can be obtained by the application of such state-of-the-art approaches