Universality of pseudogap and emergent order in lightly doped Mott insulators

It is widely believed that high-temperature superconductivity in the cuprates emerges from doped Mott insulators. The physics of the parent state seems deceivingly simple: The hopping of the electrons from site to site is prohibited because their on-site Coulomb repulsion U is larger than the kinetic energy gain t. When doping these materials by inserting a small percentage of extra carriers, the electrons become mobile but the strong correlations from the Mott state are thought to survive; inhomogeneous electronic order, a mysterious pseudogap and, eventually, superconductivity appear. How the insertion of dopant atoms drives this evolution is not known, nor whether these phenomena are mere distractions specific to hole-doped cuprates or represent the genuine physics of doped Mott insulators. Here, we visualize the evolution of the electronic states of (Sr1-xLax)2IrO4, which is an effective spin-1/2 Mott insulator like the cuprates, but is chemically radically different. Using spectroscopic-imaging STM, we find that for doping concentration of x=5%, an inhomogeneous, phase separated state emerges, with the nucleation of pseudogap puddles around clusters of dopant atoms. Within these puddles, we observe the same glassy electronic order that is so iconic for the underdoped cuprates. Further, we illuminate the genesis of this state using the unique possibility to localize dopant atoms on topographs in these samples. At low doping, we find evidence for much deeper trapping of carriers compared to the cuprates. This leads to fully gapped spectra with the chemical potential at mid-gap, which abruptly collapse at a threshold of around 4%. Our results clarify the melting of the Mott state, and establish phase separation and electronic order as generic features of doped Mott insulators.Comment: This version contains the supplementary information and small updates on figures and tex

Scientific foundations for an IUCN red list of ecosystems

An understanding of risks to biodiversity is needed for planning action to slow current rates of decline and secure ecosystem services for future human use. Although the IUCN Red List criteria provide an effective assessment protocol for species, a standard global assessment of risks to higher levels of biodiversity is currently limited. In 2008, IUCN initiated development of risk assessment criteria to support a global Red List of ecosystems. We present a new conceptual model for ecosystem risk assessment founded on a synthesis of relevant ecological theories. To support the model, we review key elements of ecosystem definition and introduce the concept of ecosystem collapse, an analogue of species extinction. The model identifies four distributional and functional symptoms of ecosystem risk as a basis for assessment criteria: A) rates of decline in ecosystem distribution; B) restricted distributions with continuing declines or threats; C) rates of environmental (abiotic) degradation; and D) rates of disruption to biotic processes. A fifth criterion, E) quantitative estimates of the risk of ecosystem collapse, enables integrated assessment of multiple processes and provides a conceptual anchor for the other criteria. We present the theoretical rationale for the construction and interpretation of each criterion. The assessment protocol and threat categories mirror those of the IUCN Red List of species. A trial of the protocol on terrestrial, subterranean, freshwater and marine ecosystems from around the world shows that its concepts are workable and its outcomes are robust, that required data are available, and that results are consistent with assessments carried out by local experts and authorities. The new protocol provides a consistent, practical and theoretically grounded framework for establishing a systematic Red List of the world’s ecosystems. This will complement the Red List of species and strengthen global capacity to report on and monitor the status of biodiversity

Deliberate self-harm and attachment: mediating and moderating roles of depression, anxiety, social support and interpersonal problems among Pakistani school going adolescents

Introduction: In Pakistan there is dearth of research on deliberate self-harm (DSH) and its predictors among adolescents. While the lack of research in Pakistan can be partly attributed to the sacrilegious status, criminalization and stigmatization attached to DSH, it is also an attribute of paucity of Urdu versions of the standardized psychological instruments. Previous research in developed countries has indicated that attachment theory can be used as a useful framework to understand the development of austere psychopathologies like DSH, as well as for studying pathways of interaction of interpersonal and intrapersonal factors of psychopathologies. In this study, standardized psychological instruments are translated into Urdu language as a first step. These instruments are then used to study pathways of interaction of interpersonal and intrapersonal factors of DSH, conceptualized within attachment framework. Method: The study was conducted in two steps. In step 1, Youth Health Risk Behavior Survey (YHRB), Inventory of Interpersonal Problems-32 (IIP-32) and Significant Others Scale (SOS), were translated into Urdu language. Along with these scales, Urdu translated versions of Hospital Anxiety and Depression Scale (HADS), Adolescent Relationship Scales Questionnaire (ARSQ), Life Events scale (LES) from CASE questionnaire and Family Affluence Scale-II (FAS-II) were reviewed for accuracy of translation through expert judgement and psychometric evaluation. Secondly, a cross sectional survey was conducted with 1290 adolescents (10 - 19 years age) using the translated Urdu versions of the instruments and demographic pro forma. Structural equation modelling was used to study the pathways of associations between predictors of DSH. Results: The extensive process of translation resulted in establishment of semantic, content, technical and construct equivalence of the translated instruments with the original English versions. Multiple imputation was performed to account for missing values in SPSS 20. Important structural adaptations were made in the scales based on factor analyses conducted in M plus. After modifications, all scales showed satisfactory CFI (≥ 0.90) and RMSEA (≤ 0.06). Results of the survey indicated that the prevalence of DSH (with, without and ambivalent suicidal intentions) was 7%. Two SEM models were constructed involving both mediation and moderation pathways. Results of Model 1 showed association of attachment with DSH was double mediated by social support, depression and anxiety. Model 2 also confirmed association of attachment with DSH with double mediation through relationship style problems, depression and anxiety. In order to understand the contextual picture of the concepts studied in this research both SEM models were also constructed by controlling for demographic factors. This resulted in confirming age, gender and family affluence as significant contributors but with very small effects. Discussion and conclusion: In the present study translation of the instruments helped in building a reservoir for future research. The results of translation and validation of instruments indicated that cultural differences, language needs and age must be accounted for while using standardized psychological instruments. Taking into consideration specific cultural and demographic background of Pakistan, this study also confirms the key role of attachment in influencing interaction of predictors of DSH. It is suggested that intrapersonal and interpersonal factors are influential points of intervention for designing clinical, school and community based awareness and prevention programs for DSH. The thesis also discusses the implications for policy guidelines along with recommendations for future research and other applications of the study

Variations in seasonal rainfall in southern Europe during the present century: Relationships with the North Atlantic Oscillation and the El Nino Southern Oscillation

Analysis of data from seventeen rainfall stations in the Iberian Peninsula, Balearic Islands and Northern Africa has revealed significant El Nino-Southern Oscillation (ENSO) signals in Europe. Both North Atlantic Oscillation (NAO) and Southern Oscillation (SO) exert an influence on Iberian climate, but at different temporal and spatial scales. Though most of the peninsula is under NAO influence in winter, some stations in the eastern region show no connection with this phenomenon. The same is found for ENSO, with a positively correlated region appearing in the eastern part of Spain, while the rest of the peninsula remains insensitive. The correlation between ENSO and Iberian rainfall has increased towards the end of the present century, with strong positive signals spanning over half of the area studied. The percentage of springtime variability due to ENSO has similarly increased, reaching up to 50% in certain areas. We also show how there are outstanding climatic sensors of these phenomena such as Lake Gallocanta, which manifests a positive response to ENSO while appears insensitive to NAO. Common long-term patterns are observed between SOI and an inferred lake level series, suggesting a constant influence of the low-frequency component of ENSO throughout the period considered. Lake drying phases every 14 years reflect the impact of this signal, approximately every four ENSO events