Magnetic properties of the two-dimensional Heisenberg model on a triangular lattice

The spin Green's function of the antiferromagnetic Heisenberg model on a triangular lattice is calculated using Mori's projection operator technique. At T=0 the spin excitation spectrum is shown to have gaps at the wave vectors of the classical Neel ordering. This points to the absence of the antiferromagnetic long-range order in the ground state. The calculated spin correlation on the neighboring sites of the same sublattice is in good agreement with the value derived from exact diagonalization. The temperature dependencies of the spin correlations and the gaps are calculated.Comment: 5 pages, 3 figure

Concerns about losing face moderate the effect of visual perspective on health-related intentions and behaviors

Visualizing oneself engaging in future actions has been shown to increase the likelihood of actually engaging in the visualized action. In three studies, we examined the effect of perspective taken to visualize a future action (first-person vs. third-person) as a function of the degree to which individuals worry about others’ evaluation of themselves (face) and whether the visualized behavior is public or private. Across all studies, the effect of visual perspective was present only for participants with high level of face. In this group, the third-person visualization induced stronger intentions to engage in the behavior when the imagined behavior was public (Study 1), whereas the first-person visualization induced stronger intentions and greater likelihood to engage in that behavior when it was private (Study 2). The influence of the first-person perspective on flossing behavior was eliminated when people with high levels of face were encouraged to consider inter-personal consequences of the action (Study 3). Results are discussed in the light of recent theorizing on the cognitive consequences of taking a third-person versus a first-person perspective in visual imagery

Social and Non-social Brain Areas in Risk Behaviour: The Role of Social Context

This work was supported by the Spanish Ministry of Economy, Industry, and Competitiveness through a grant awarded (PSI2016-80558-R to A.Catena) and a postdoctoral contract of the University of Granada (to S. Baltruschat) .The human brain contains social areas that become active when interacting with another human. These are located in the ventral prefrontal and mediodorsal cortices, adjacent to areas involved in reward processing and cognitive control. Human behaviour is strongly influenced by the social context. This is particularly evident when observing greater risk propensity in the presence of a peer, particularly during adolescence and emerging adulthood. We explored the widely held view that enhanced risk propensity is the consequence of weak cognitive control. We used brain activity, estimated from EEG recordings in a sample of 114 emerging adult dyads whilst performing a risk perception task, to predict risk behaviour in a subsequent driving simulation task. Being with a peer reduced the ability to discriminate riskiness in images of traffic scenes, biased responses towards the perception of no-risk, and increased the rate of accidents in the driving simulation. Risk perception involved three sets of clusters showing activity only when being with a peer, only when being alone, and in both social contexts. Functional connectivity between the clusters accounted for the later driving simulation performance depending on the peer’s presence. In the light of our findings, greater risk-taking, when a peer is present, seems to be triggered by the activation of a different, less efficient brain network for risk-processing.Spanish Ministry of Economy, Industry, and Competitiveness PSI2016-80558-RUniversity of Granad

Spatial Structure of Spin Polarons in the t-J Model

The deformation of the quantum Neel state induced by a spin polaron is analyzed in a slave fermion approach. Our method is based on the selfconsistent Born approximation for Green's and the wave function for the quasiparticle. The results of various spin-correlation functions relative to the position of the moving hole are discussed and shown to agree with those available from small cluster calculations. Antiferromagnetic correlations in the direct neighborhood of the hole are reduced, but they remain antiferromagnetic even for J as small as 0.1 t. These correlation functions exhibit dipolar distortions in the spin structure, which sensitively depend on the momentum of the quasiparticle. Their asymptotic decay with the distance from the hole is governed by power laws, yet the spectral weight of the quasiparticles does not vanish.Comment: 12 pages, 2 postscipt files with figures; uses REVTeX, to be published in Phys. Rev. B, Feb. 199

Internal plate fixation of fractures: short history and recent developments

Metal plates for internal fixation of fractures have been used for more than 100 years. Although initial shortcomings such as corrosion and insufficient strength have been overcome, more recent designs have not solved all problems. Further research is needed to develop a plate that accelerates fracture healing while not interfering with bone physiology

A Systematic Review of Side Effects of Nucleoside and Nucleotide Drugs Used for Treatment of Chronic Hepatitis B

Although nucleosides and nucleotides have a good safety record for the treatment of hepatitis B, there have been no systematic reviews on this topic. We searched Medline to include studies of the oral antiviral agents for hepatitis B and adverse events, with at least 48 weeks of follow-up from the initiation of treatment with the drug. Important toxicities include nephrotoxicity, myopathy, and resistance. It is often difficult to ascertain whether an adverse effect is from the study drug or the natural progression of the disease. Further safety data are needed for the newer agents and for all agents with regard to patients with decompensated liver disease, renal dysfunction, the elderly, children, and pregnant women

Patients’ experience of recurrent/metastatic head and neck squamous cell carcinoma and their perspective on the EORTC QLQC30 and QLQ-H&N35 questionnaires: a qualitative study

Abstract Background Head and neck squamous cell carcinoma (HNSCC) and its associated treatments may affect all aspects of patients’ health-related quality of life (HRQoL). Although the EORTC QLQ-H&N35 is regularly administered to patients with HNSCC, there is a paucity of studies re-assessing the conceptual relevance of this patient-reported outcome (PRO) measure from a patient perspective. Furthermore, the content validity of the EORTC QLQ-C30 has not been widely documented in patients with recurrent and/or metastatic HNSCC. The objectives of this study were to understand patients’ experiences of recurrent/metastatic HNSCC and its treatments, and to evaluate the conceptual relevance and acceptability of the EORTC QLQ-C30 and QLQ-H&N35 from a patient perspective for use in clinical trials. Methods A literature review and clinician interviews were conducted to inform in-depth semi-structured telephone interviews with US patients who had received treatment for recurrent and/or metastatic HNSCC in the preceding 12 months. Interview transcripts were analysed thematically using ATLAS.ti v7; patient quotes were coded to identify concepts and themes to develop a conceptual model of HNSCC experience. Results Fourteen patients were interviewed (71% male, aged 35–84 years). Patients reported few symptoms pre-diagnosis including neck lump/swelling (n = 7/14, 50%) and/or difficulty swallowing (n = 3/14, 21%). Treatments generally comprised surgery and chemotherapy and/or radiotherapy. A number of side effects from all treatments were reported. Numbness, difficulty speaking and pain were the most reported side effects of surgery (n = 4/8, 50%); weight loss and fatigue were the most reported side effects of chemotherapy and/or radiotherapy (n = 8/13, 61%). All side effects negatively impacted patients’ HRQoL. Patients generally found the QLQ-C30 and QLQ H&N35 content to be understandable and conceptually relevant; excessive mucous production and neuropathic symptoms were among the suggested additions. Conclusions HNSCC and its diverse symptoms and treatments have a negative impact on many aspects of patients’ lives. A number of reported symptoms including difficulty speaking and swallowing, localised pain and fatigue may be important for treatment benefit evaluation in clinical trials from a patient perspective. The QLQ-C30 and QLQ-H&N35 are generally relevant and suitable for use in clinical trials. However, some items could be amended/added to ensure conceptual comprehensiveness of these measures

A systematic review of the efficacy of alcohol interventions for incarcerated people

Aim: The aim of this current study was to systematically review the literature on brief alcohol interventions for incarcerated individuals to ascertain the efficacy or effectiveness in making changes to either consumption of alcohol or other social outcomes. Short summary: Levels of risky drinking and dependency are high amongst incarcerated individuals. Eleven studies from nine articles were included in the systematic review. Six of the studies included brief intervention and three extended interventions. Interventions have the potential to positively impact on risky drinking. More studies are needed in this setting. Introduction: It has been shown that around three times as many incarcerated individuals are risky drinkers and alcohol dependency is ten times higher than in the general population. Methods: Systematic review of randomised controlled trials or matched group trials of the efficacy of psychosocial alcohol interventions for incarcerated individuals: we searched seven databases, with no restrictions on language, year or location from inception through to August 2017. The Critical Appraisal Skills Programme tool was used to assess the quality of included studies. The Template for Intervention Description and Replication checklist was used to ascertain intervention descriptions. Results: Nine studies from 11 papers were included in the analysis. Six of the studies included brief interventions and three extended interventions. Every study used a different measure of alcohol consumption. Three of the studies that looked at brief interventions and all of the three extended intervention studies found significant reductions in relation to alcohol outcomes. Conclusions: Results show that interventions in the prison setting have the potential to positively impact on alcohol use; however, because of small numbers and the use of different outcome measures we could not conduct a meta-analysis or generalise findings. Future studies are needed to standardise approaches to ensure greater rigour and efficacy

Degradation of Mouse Invariant Chain: Roles of Cathepsins S and D and the Influence of Major Histocompatibility Complex Polymorphism

Antigen-presenting cells (APC) degrade endocytosed antigens into peptides that are bound and presented to T cells by major histocompatibility complex (MHC) class II molecules. Class II molecules are delivered to endocytic compartments by the class II accessory molecule invariant chain (Ii), which itself must be eliminated to allow peptide binding. The cellular location of Ii degradation, as well as the enzymology of this event, are important in determining the sets of antigenic peptides that will bind to class II molecules. Here, we show that the cysteine protease cathepsin S acts in a concerted fashion with other cysteine and noncysteine proteases to degrade mouse Ii in a stepwise fashion. Inactivation of cysteine proteases results in incomplete degradation of Ii, but the extent to which peptide loading is blocked by such treatment varies widely among MHC class II allelic products. These observations suggest that, first, class II molecules associated with larger Ii remnants can be converted efficiently to class II–peptide complexes and, second, that most class II–associated peptides can still be generated in cells treated with inhibitors of cysteine proteases. Surprisingly, maturation of MHC class II in mice deficient in cathepsin D is unaffected, showing that this major aspartyl protease is not involved in degradation of Ii or in generation of the bulk of antigenic peptides