Electronic and magnetic properties of the monolayer RuCl3_3: A first-principles and Monte Carlo study

Recent experiments revealed that monolayer $\alpha$-RuCl$_3$ can be obtain by chemical exfoliation method and exfoliation or restacking of nanosheets can manipulate the magnetic properties of the materials. In this present paper, the electronic and magnetic properties of $\alpha$-RuCl$_3$ monolayer are investigated by combining first-principles calculations and Monte Carlo simulations. From first-principles calculations, we found that the spin configuration FM corresponds to the ground state for $\alpha$-RuCl$_3$, however, the other excited zigzag oriented spin configuration has energy of 5 meV/atom higher than the ground state. Energy band gap has been obtained as $3$ meV using PBE functionals. When spin-orbit coupling effect is taken into account, corresponding energy gap is determined to be as $57$ meV. We also investigate the effect of Hubbard U energy terms on the electronic band structure of $\alpha$-RuCl$_3$ monolayer and revealed band gap increases approximately linear with increasing U value. Moreover, spin-spin coupling terms ($J_1$, $J_2$, $J_3$) have been obtained using first principles calculations. By benefiting from these terms, Monte Carlo simulations with single site update Metropolis algorithm have been implemented to elucidate magnetic properties of the considered system. Thermal variations of magnetization, susceptibility and also specific heat curves indicate that monolayer $\alpha$-RuCl$_3$ exhibits a phase transition between ordered and disordered phases at the Curie temperature $14.21$ K. We believe that this study can be utilized to improve two-dimensional magnet materials

Laparoscopic versus Open Appendectomy: Where Are We Now?

Rezumat Apendicectomia prin abord laparoscopic versus abord deschis: pentru ce optãm? Scop: Deaei avantajele procedurilor laparoscopice au fost intens studiate pe parcursul ultimelor douã decenii, apendicectomia laparoscopicã nu a putut fi desemnatã ca procedurã standard de tratament din cauza unor dezavantaje de tipul timpilor operatori aei al costurilor crescute. Obiectivul studiului nostru este de a reevalua rezultatele pe termen lung ale abordului laparoscopic versus cel chirurgical deschis pentru aceastã patologie pe baza datelor actuale. Metode: Datele pacienåilor supuaei apendicectomiei între ianuarie 2012 aei iulie 2012 au fost analizate prospectiv. Datele demografice ale pacienåilor, durata procedurii, perioada de internare, nevoia de analgezice, scorul VAS aei rata mortalitãåii au fost înregistrate. Rezultate: Din 241 de pacienåi, 120 (49.8%) au suferit intervenåie deschisã aei 121 (50.2%) au fost operaåi laparoscopic. Perioada intervenåiei a fost similarã între cele douã grupuri (p=0.855). Scorurile VAS dupã prima orã (p=0.001), dupã 6 (p=0.001) aei dupã 12 ore de la operaåie (p=0.028) au fost mai mari în grupul de apendicectomii prin abord deschis (p=0.001). Nu au existat diferenåe statistice vizând ratele de morbiditate între grupul prin abord deschis aei cel prin abord laparoscopic (p=0.617). Concluzii: Cele douã tehnici operatorii sunt similare în ceea ce priveaete perioada de internare, durata operaåiei aei complicaåiile postoperatorii. Apendicectomia laparoscopicã reduce nevoia de analgezice aei scorurile VAS; aceasta ar trebui prin urmare luatã în considerare ca standard de aur în tratamentul chirurgical al apendicitei acute. Cuvinte cheie: apendicitã, apendicectomie, procedurã laparoscopicã, abces abdominal, infecåia plãgii chirurgicale Abstract Purpose: Although the advantages of laparoscopic procedures has been well studied over the last two decade, laparoscopic appendectomy could not to be a standard therapy due to some disadvantages such as longer operative time and higher cost. The objective of our study is to re-evaluate the outcomes of laparoscopic versus open appendectomy with current data. Methods: Between January 2012 and July 2012, the data of the patients who had appendectomy were recorded prospectively. Patients' demographics, duration of procedure, length of hospital stay, need of analgesics, postoperative visual analogue scale scores and morbidity were assessed

SUNNY-CP : a Sequential CP Portfolio Solver

International audienceThe Constraint Programming (CP) paradigm allows to model and solve Constraint Satisfaction / Optimization Problems (CSPs / COPs). A CP Portfolio Solver is a particular constraint solver that takes advantage of a portfolio of different CP solvers in order to solve a given problem by properly exploiting Algorithm Selection techniques. In this work we present sunny-cp: a CP portfolio for solving both CSPs and COPs that turned out to be competitive also in the MiniZinc Challenge, the reference competition for CP solvers

Infant contact in day-care centres in Vietnam: A cross-sectional study to understand infant infection risk

Background: Infant contact information (skin-to-skin contact between infants and others) is important to understand Streptococcus pneumoniae transmission patterns. A few studies have investigated infant contact patterns by asking the mother/guardian to record all contacts a child makes in one day. However, this approach does not capture contact behaviour in day-care. Our study describes the frequency and nature of physical contacts of infants in day-care to understand infant infection risk in day-care in Nha Trang, central Vietnam. Methods: This cross-sectional study enrolled infants aged less than 12 months, attending 10 randomly selected day-care centres in Nha Trang. Physical contacts of each infant for one day at the day-care centre were observed and recorded. The mean number of contacts of infants and its factors were assessed using negative binomial regression. Results: In total 14 infants, aged 6 to 11 months, were enrolled, and a total of 96 contacts were observed. The mean number of contacts an infant made in one day was 6.9. Infants who walked independently (age-adjusted rate ratio 1.68, 95% confidence interval 1.06-2.68) and those cared for in a larger group (1.99, 1.42-2.79) had more contacts at day-care. About 50% of infants made contact with at least one person from a commune different from the infant\u27s, and 50% made contact with at least one other infant at day-care. Conclusion: This study found that day-care attendance may be one factor that increases contact rates of infants in Nha Trang and diversifies them in terms of age and geographical spread. In this study, day-care attendance not only increased contact rates beyond those usually experienced by young children cared at home but specifically increased the contact rates with other children and adults from other communes. Day-care may play a key role in the transmission of respiratory pathogens like Streptococcus pneumoniae to infants

Human Nasal Challenge with Streptococcus pneumoniae Is Immunising in the Absence of Carriage

Infectious challenge of the human nasal mucosa elicits immune responses that determine the fate of the host-bacterial interaction; leading either to clearance, colonisation and/or disease. Persistent antigenic exposure from pneumococcal colonisation can induce both humoral and cellular defences that are protective against carriage and disease. We challenged healthy adults intra-nasally with live 23F or 6B Streptococcus pneumoniae in two sequential cohorts and collected nasal wash, bronchoalveolar lavage (BAL) and blood before and 6 weeks after challenge. We hypothesised that both cohorts would successfully become colonised but this did not occur except for one volunteer. The effect of bacterial challenge without colonisation in healthy adults has not been previously assessed. We measured the antigen-specific humoral and cellular immune responses in challenged but not colonised volunteers by ELISA and Flow Cytometry. Antigen-specific responses were seen in each compartment both before and after bacterial challenge for both cohorts. Antigen-specific IgG and IgA levels were significantly elevated in nasal wash 6 weeks after challenge compared to baseline. Immunoglobulin responses to pneumococci were directed towards various protein targets but not capsular polysaccharide. 23F but not 6B challenge elevated IgG anti-PspA in BAL. Serum immunoglobulins did not increase in response to challenge. In neither challenge cohort was there any alteration in the frequencies of TNF, IL-17 or IFNγ producing CD4 T cells before or after challenge in BAL or blood. We show that simple, low dose mucosal exposure with pneumococci may immunise mucosal surfaces by augmenting anti-protein immunoglobulin responses; but not capsular or cellular responses. We hypothesise that mucosal exposure alone may not replicate the systemic immunising effect of experimental or natural carriage in humans

Role of Fibronectin in the Adhesion of Acinetobacter baumannii to Host Cells

Adhesion to host cells is an initial and important step in Acinetobacter baumannii pathogenesis. However, there is relatively little information on the mechanisms by which A. baumannii binds to and interacts with host cells. Adherence to extracellular matrix proteins, such as fibronectin, affords pathogens with a mechanism to invade epithelial cells. Here, we found that A. baumannii adheres more avidly to immobilized fibronectin than to control protein. Free fibronectin used as a competitor resulted in dose-dependent decreased binding of A. baumannii to fibronectin. Three outer membrane preparations (OMPs) were identified as fibronectin binding proteins (FBPs): OMPA, TonB-dependent copper receptor, and 34 kDa OMP. Moreover, we demonstrated that fibronectin inhibition and neutralization by specific antibody prevented significantly the adhesion of A. baumannii to human lung epithelial cells (A549 cells). Similarly, A. baumannii OMPA neutralization by specific antibody decreased significantly the adhesion of A. baumannii to A549 cells. These data indicate that FBPs are key adhesins that mediate binding of A. baumannii to human lung epithelial cells through interaction with fibronectin on the surface of these host cells