Extended Quantum Dimer Model and novel valence-bond phases

We extend the quantum dimer model (QDM) introduced by Rokhsar and Kivelson so as to construct a concrete example of the model which exhibits the first-order phase transition between different valence-bond solids suggested recently by Batista and Trugman and look for the possibility of other exotic dimer states. We show that our model contains three exotic valence-bond phases (herringbone, checkerboard and dimer smectic) in the ground-state phase diagram and that it realizes the phase transition from the staggered valence-bond solid to the herringbone one. The checkerboard phase has four-fold rotational symmetry, while the dimer smectic, in the absence of quantum fluctuations, has massive degeneracy originating from partial ordering only in one of the two spatial directions. A resonance process involving three dimers resolves this massive degeneracy and dimer smectic gets ordered (order from disorder).Comment: 20 pages, 13 figures, accepted for publication in J. Stat. Mec

Customer abuse and harassment in the hospitality industry: the immersion of an everyday workplace crime

This article, drawing on the General Strain Theory (GST), discusses customer abuse and harassment in the Greek hospitality sector during the unprecedented strain of the Covid-19 pandemic. The study draws on an online survey questionnaire, incorporating a combination of open-ended and closed questions to secure both qualitative and quantitative data. Customer abuse and harassment are outlined as endemic phenomena of workplace violence in the industry, and workplace crimes that were further intensified because of the pandemic. Managerial immoral inaction towards customer misbehaviour, as well as the underreporting of this issue, are discussed as impeding factors in addressing customer abuse and harassment. The study’s theoretical contribution stems from the examination of abuse and harassment from a criminology perspective, employing the GST and the classification of such (mis)behaviours as an everyday workplace crime, which remains unmanaged, accepted, and tolerated in the hospitality and tourism sector, violating employees’ well-being and dignity at work

Morally disengaged managers and customers on the service front-line: evidence from the Greek tourism and hospitality sector during the pandemic.

Customer abuse remains a pervasive social problem that is widespread across the service sector, which has been exacerbated because of the Covid-19 pandemic, affecting employee wellbeing (Hadjisolomou and Simone, 2021). Worryingly, authors argue that customer abuse has become a social norm (Taylor, 2019) which is developed, facilitated, and strengthened by service cultures within which the customer ‘is always right’ (Korczynski and Evans, 2013). This reinforces the perception that customers may abuse service workers, without evident penalties for their (mis)behaviour whilst management tolerates such behaviour. This uncomfortable truth poses important questions regarding morality in the service employment relationship that warrants further and theoretical and empirical attention. This paper, building on Sayer’s moral economy framework, discusses moral disengagement by managers and customers within the triangular employment relationship in the Greek hospitality and tourism sector. Sayer (2007) reports that humans are ethical social beings who evaluate behaviour and actions that affect well-being, whilst Bolton and Laaser (2013), reflecting on Sayer’s focus on human flourishment, stress an essential sociological inquiry: if and how capitalism dehumanizes workers. This paper contributes to this enquiry exploring customer abuse in a period of socio economic crisis. Drawing on a survey conducted during the Covid-19 period, research findings indicate that customer abuse continued during the pandemic, whilst respondents have emphasized the inactive role of management in protecting workers. Specifically, 53% of respondents have reported that they have experienced abuse and 67% witnessed abuse in the workplace, with the customer being identified as the main perpetrator. Alarmingly, however, from those who have reported the abuse to management, only 20% have reported that action was taken and only for the 19% reporting has improved the situation. This shows that front-line employees are part of social and employment structures that are ethically problematic, especially in a period of crisis. Arguably, customers are morally disengaged detaching themselves from moral actions when interacting with service workers, whilst they rationalize abuse and the abandonment of moral principles drawing on the ‘customer is always right’ culture found in organizations (Yakut, 2021). Along similar lines, management is morally disengaged by tolerating, and neglecting abuse on the front-end and failing to act and protect workers. The paper reveals another level of complexity in organizations which is related to the notion of power imbalance within the service triangle and its impact on morality and workers’ wellbeing (Sayer, 2011). Accepting Sayer’s (2011) argument that organisations are ‘important ‘moral arenas’ for their members, this paper questions morality on the services front-end and within the service triangle, where the powerful and immoral acts of customers, which violate employee wellbeing, are being tolerated and neglected by management. Managerial actions to protect workers are limited within a customer-oriented culture that is driven by market dynamics (Hadjisolomou and Simone, 2021). This reinforces Sayer’s argument that markets are the major force weakening the moral economy and driving moral disengagement within organizations. Understandably, market pressures, especially in a period of crisis, force management and customers to act, ‘if not immorally, then at least amorally’ (Sayer, 2000; 91)

Adherence and Constancy in LIME-RS Explanations for Recommendation

Explainable Recommendation has attracted a lot of attention due to a renewed interest in explainable artificial intelligence. In particular, post-hoc approaches have proved to be the most easily applicable ones to increasingly complex recommendation models, which are then treated as black boxes. The most recent literature has shown that for post-hoc explanations based on local surrogate models, there are problems related to the robustness of the approach itself. This consideration becomes even more relevant in human-related tasks like recommendation. The explanation also has the arduous task of enhancing increasingly relevant aspects of user experience such as transparency or trustworthiness. This paper aims to show how the characteristics of a classical post-hoc model based on surrogates is strongly model-dependent and does not prove to be accountable for the explanations generatedThe authors acknowledge partial support of PID2019-108965GB-I00, PONARS01_00876BIO-D,CasadelleTecnologie mergenti della Cittàdi Matera, PONARS01_00821FLET4.0, PIAServiziLocali2.0,H2020Passapartout-Grantn. 101016956, PIAERP4.0,andIPZS-PRJ4_IA_NORMATIV

Line managers' perceptions of diversity management: insights from a social exchange theory perspective

Purpose: Drawing on the social exchange theory, this study aims to explore line managers' perceptions of diversity management, as well as their perceptions of their role and responsibilities in shaping and implementing diversity practices. The senior management's leadership support, as it is perceived by line managers, in assisting them to manage diversity successfully is also examined. Design/methodology/approach: Semi-structured interviews with 51 line managers across different sectors in the UK were conducted to address the following three research questions. First, how do line managers perceive diversity management? Second, what are the actual roles and responsibilities of line managers in shaping diversity practices' implementation? Third, how do leadership interactions within the organisation influence line managers' perceptions of diversity practices? Findings: Line managers present high levels of personal determination and commitment towards diversity supplemented by a consensus on the strategic role of leadership in relation to diversity management. In addition, poor levels of organisational support, leadership values and style are identified; all highly related to their ability to deliver results and, most importantly, to form effective relationships in the workplace. Research limitations/implications: Data included line managers' views but not senior managers' perspectives, thus limiting the study in identifying the holistic impact of social exchanges in shaping effective relations. In addition, quantitative research could test and enhance the generalisability of existing findings. Practical implications: Investing in social relationships can positively influence line managers' ability to deliver results. Action is required at the organisational level by senior management to support and recognise line managers' critical roles to enable them to apply and promote diversity management. Originality/value: These findings address a theoretical gap relating to the evaluation of the critical role played by line managers in the delivery of diversity practices. The study further demonstrates how social exchange relationships can influence line managers' perceptions of diversity management, an unexplored area within the diversity literature

Can retention forestry help conserve biodiversity?

Industrial forestry typically leads to a simplified forest structure and altered species composition. Retention of trees at harvest was introduced about 25years ago to mitigate negative impacts on biodiversity, mainly from clearcutting, and is now widely practiced in boreal and temperate regions. Despite numerous studies on response of flora and fauna to retention, no comprehensive review has summarized its effects on biodiversity in comparison to clearcuts as well as un-harvested forests. Using a systematic review protocol, we completed a meta-analysis of 78 studies including 944 comparisons of biodiversity between retention cuts and either clearcuts or un-harvested forests, with the main objective of assessing whether retention forestry helps, at least in the short term, to moderate the negative effects of clearcutting on flora and fauna. Retention cuts supported higher richness and a greater abundance of forest species than clearcuts as well as higher richness and abundance of open-habitat species than un-harvested forests. For all species taken together (i.e. forest species, open-habitat species, generalist species and unclassified species), richness was higher in retention cuts than in clearcuts. Retention cuts had negative impacts on some species compared to un-harvested forest, indicating that certain forest-interior species may not survive in retention cuts. Similarly, retention cuts were less suitable for some open-habitat species compared with clearcuts. Positive effects of retention cuts on richness of forest species increased with proportion of retained trees and time since harvest, but there were not enough data to analyse possible threshold effects, that is, levels at which effects on biodiversity diminish. Spatial arrangement of the trees (aggregated vs. dispersed) had no effect on either forest species or open-habitat species, although limited data may have hindered our capacity to identify responses. Results for different comparisons were largely consistent among taxonomic groups for forest and open-habitat species, respectively.Synthesis and applications. Our meta-analysis provides support for wider use of retention forestry since it moderates negative harvesting impacts on biodiversity. Hence, it is a promising approach for integrating biodiversity conservation and production forestry, although identifying optimal solutions between these two goals may need further attention. Nevertheless, retention forestry will not substitute for conservation actions targeting certain highly specialized species associated with forest-interior or open-habitat conditions.Our meta-analysis provides support for wider use of retention forestry since it moderates negative harvesting impacts on biodiversity. Hence, it is a promising approach for integrating biodiversity conservation and production forestry, although identifying optimal solutions between these two goals may need further attention. Nevertheless, retention forestry will not substitute for conservation actions targeting certain highly specialized species associated with forest-interior or open-habitat conditions

Extreme oxygen isotope zoning in garnet and zircon from a metachert block in melange reveals metasomatism at the peak of subduction metamorphism

A tectonic block of garnet quartzite in the amphibolite-facies melange of the Catalina Schist (Santa Catalina Island, California, USA) records the metasomatic pre-treatment of high-delta O-18 sediments as they enter the subduction zone. The block is primarily quartz, but contains two generations of garnet that record extreme oxygen isotope disequilibrium and inverse fractionations between garnet cores and matrix quartz. Rare millimeter-scale garnet crystals record prograde cation zoning patterns, whereas more abundant similar to 200-mu m-diameter crystals have the same composition as rims on the larger garnets. Garnets of both generations have high-delta O-18 cores (20.8 parts per thousand-26.3 parts per thousand, Vienna standard mean ocean water) that require an unusually high-delta O-18 protolith and lower-delta O-18, less variable rims (10.0 parts per thousand-11.2 parts per thousand). Matrix quartz values are homogeneous (13.6 parts per thousand). Zircon crystals contain detrital cores (delta O-18 = 4.7 parts per thousand-8.5 parts per thousand, 124.6 + 1.4/-2.9 Ma) with a characteristic igneous trace element composition likely sourced from arc volcanics, surrounded by zircon with metamorphic age (115.1 +/- 2.5 Ma) and trace element compositions that suggest growth in the presence of garnet. Metamorphic zircon decreases in delta O-18 from near-core (24.1 parts per thousand) to rim (12.4 parts per thousand), in equilibrium with zoned garnets. Collectively, the data document the subduction of a mixed high-delta O-18 siliceous ooze and/or volcanic ash protolith reaching temperatures of 550-625 degrees C prior to the nucleation of small garnets without influence from external fluids. Metasomatism was recorded in rims of both garnet and zircon populations as large volumes of broadly homogeneous subduction fluids stripped matrix quartz of its extremely high oxygen isotope signature. Thus, zoned garnet and zircon in high-delta O-18 subducted sediments offer a detailed window into subduction fluids

Genetic regulation of pituitary gland development in human and mouse

Normal hypothalamopituitary development is closely related to that of the forebrain and is dependent upon a complex genetic cascade of transcription factors and signaling molecules that may be either intrinsic or extrinsic to the developing Rathke’s pouch. These factors dictate organ commitment, cell differentiation, and cell proliferation within the anterior pituitary. Abnormalities in these processes are associated with congenital hypopituitarism, a spectrum of disorders that includes syndromic disorders such as septo-optic dysplasia, combined pituitary hormone deficiencies, and isolated hormone deficiencies, of which the commonest is GH deficiency. The highly variable clinical phenotypes can now in part be explained due to research performed over the last 20 yr, based mainly on naturally occurring and transgenic animal models. Mutations in genes encoding both signaling molecules and transcription factors have been implicated in the etiology of hypopituitarism, with or without other syndromic features, in mice and humans. To date, mutations in known genes account for a small proportion of cases of hypopituitarism in humans. However, these mutations have led to a greater understanding of the genetic interactions that lead to normal pituitary development. This review attempts to describe the complexity of pituitary development in the rodent, with particular emphasis on those factors that, when mutated, are associated with hypopituitarism in humans

Immunoregulatory gene polymorphisms in women with preeclampsia

The costimulatory molecules CD28, cytotoxic T-lymphocyte antigen-4 (CTLA-4) (cytotoxic T-lymphocyte-associated antigen-4) and inducible costimulator (ICOS) are believed to have a critical modulatory role in the immune response. However, few studies have been performed on the role of these immune regulatory molecules and their polymorphisms in women with preeclampsia (PE). the aim of our study was to evaluate the CTLA4 (+49 A/G) (rs 231775), CD28 (+17 T/C) (rs 3116496) and ICOS (-1564 T/C) (rs 4675378) gene polymorphisms in Brazilian women with PE. This case-control study included 130 patients with PE and 261 control women without any obstetric or systemic disorders. Genomic DNA was extracted from peripheral blood, and the polymorphism genotyping was performed by digesting the PCR products with the restriction endonucleases BbvI (CTLA-4), Afel (CD28) and AluI (ICOS). Data were analyzed by X(2) or Fisher's exact test; a P-value of < 0.05 was considered as significant. There were significant differences in the ICOS genotype and allelic frequencies between the PE and control groups (P=0.01 and P=0.01, respectively). We found a significantly lower frequency of the ICOS (-1564) T allele in women with mild PE compared with the controls. There were no differences in the CTLA-4 (+49 A/G) and CD28 (+17 T/C) genotypes and allelic frequencies between the PE patients and controls. Our data suggest that PE is associated with ICOS, but is not associated with the CTLA-4 or CD28 gene polymorphisms. Hypertension Research (2011) 34, 384-388; doi:10.1038/hr.2010.247; published online 16 December 2010Fundacao de Amparo a PesquisaCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Universidade Federal de São Paulo, Dept Obstet, BR-01415002 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Obstet, BR-01415002 São Paulo, BrazilFundacao de Amparo a Pesquisa: 07/57446-0Web of Scienc