Imaging Electronic Correlations in Twisted Bilayer Graphene near the Magic Angle

Twisted bilayer graphene with a twist angle of around 1.1{\deg} features a pair of isolated flat electronic bands and forms a strongly correlated electronic platform. Here, we use scanning tunneling microscopy to probe local properties of highly tunable twisted bilayer graphene devices and show that the flat bands strongly deform when aligned with the Fermi level. At half filling of the bands, we observe the development of gaps originating from correlated insulating states. Near charge neutrality, we find a previously unidentified correlated regime featuring a substantially enhanced flat band splitting that we describe within a microscopic model predicting a strong tendency towards nematic ordering. Our results provide insights into symmetry breaking correlation effects and highlight the importance of electronic interactions for all filling factors in twisted bilayer graphene.Comment: Main text 9 pages, 4 figures; Supplementary Information 25 page

Regulation and marketisation in the Portuguese higher education system

This paper builds on the ongoing discussion on regulation and marketisation of higher education. It aims at investigating the higher education market (des)equilibrium. Teixeira, Rosa and Amaral (2004) have analysed the presence/absence of market mechanisms in the Portuguese higher education sector. We go a step further in quantifying the (mis)mactching between demand and supply, by suggesting and computing a set of indicators, which provide the starting point for a ranking-based analysis. Institutional rankings are central to overcome the problem of absence of information on quality in higher education systems, which is a basic requirement for a real higher education market.higher education market, demand, supply

The impact of family policy packages on fertility trends in developed countries.

We examine how far fertility trends respond to family policies in OECD countries. In the light of the recent fertility rebound observed in several OECD countries, we empirically test the impact of different family policy settings on fertility, using data from 18 OECD countries that spans the years 1982 to 2007. Our results confirm that each instrument of the family policy package (paid leave, childcare services and financial transfers) has a positive influence, suggesting that the addition of these supports for working parents in a continuum during the early childhood is likely to facilitate parents' choice to have children. Policy levers do not have similar weight, however: in-cash benefits covering childhood after the year of childbirth and the coverage of childcare services for children under age three have a larger potential influence on fertility than leave entitlements and benefits granted around childbirth. Our findings are robust once controlling for birth postponement, endogeneity, time lagged fertility reactions and for different national contexts, such as economic development, female employment rates, labour market insecurity and childbearing norms.family policies; fertility; demographic economics; female employment; economics of gender

From association to causality: the new frontier for complex traits

Technological and analytical advances have led to an unprecedented catalog of genomic regions associated with a broad range of clinically relevant phenotypes in humans. However, some examples notwithstanding, the causes of the overwhelming majority of genetic diseases remain obscure. More importantly, an emerging lesson from genome-wide association studies is that, in most instances, the resolution necessary for identifying actual genes that underlie the phenotype is limited, as is our ability to develop mechanistic, testable disease models from such studies. These new realities will probably necessitate a paradigm shift in our approach to complex traits, for which the combinatorial application of genomic and functional studies will be necessary to understand the mechanism and pathology of genetic disease. Here I will discuss these issues and highlight how additional sequencing and genotyping of ever-increasing cohort sizes without functional interpretation is unlikely to improve our ability to dissect the genetic basis of complex traits

Translational bioinformatics applications in genome medicine

Although investigators using methodologies in bioinformatics have always been useful in genomic experimentation in analytic, engineering, and infrastructure support roles, only recently have bioinformaticians been able to have a primary scientific role in asking and answering questions on human health and disease. Here, I argue that this shift in role towards asking questions in medicine is now the next step needed for the field of bioinformatics. I outline four reasons why bioinformaticians are newly enabled to drive the questions in primary medical discovery: public availability of data, intersection of data across experiments, commoditization of methods, and streamlined validation. I also list four recommendations for bioinformaticians wishing to get more involved in translational research

Genetics of Alzheimer's disease: recent advances

Alzheimer's disease is a progressive neurodegenerative disorder with high prevalence in old age. It is the most common cause of dementia, with a risk reaching 50% after the age of 85 years, and with the increasing age of the population it is one of the biggest healthcare challenges of the 21st century. Genetic variation is an important contributor to the risk for this disease, underlying an estimated heritability of about 70%. Alzheimer's genetics research in the 1990s was successful in identifying three genes accounting for most cases of early-onset disease with autosomal dominant inheritance, and one gene involved in the more common late-onset disease, which shows complex inheritance patterns. Despite the presence of significant remaining genetic contribution to the risk, the identification of genes since then has been elusive, reminiscent of most other complex disorders. In the past decade there have been significant efforts towards a systematic evaluation of the multiple genetic association studies for Alzheimer's disease, while the first genome-wide association studies are now being reported with promising results. As sample sizes grow through new collections and collaborative efforts, and as new technologies make it possible to test alternative hypotheses, it is expected that new genes involved in the disease will soon be identified and confirmed. The gene discoveries of the 1990s have taught us a lot about Alzheimer's disease pathogenesis, providing many therapeutic targets that are currently at various stages of testing for future clinical use. As new genes become known and the biological pathways leading to disease are further explored, the possibility of prevention and successful personalized treatment is becoming tangible, providing hope for the millions of patients with Alzheimer's disease and their caregivers

Dissecting complex traits: recent advances in hypertension genomics

Genome-wide association scans are beginning to identify risk alleles for a number of complex diseases and traits. Essential hypertension looked as though it would be an exception to this trend after the Wellcome Trust Case Control Consortium data were published in 2007. However, more recent scans and meta-analyses have reversed the fortunes of essential hypertension. A number of loci have been identified, including a new antihypertensive drug target in the guise of the serine/threonine kinase SPAK. This kinase forms part of a novel kinase cascade that regulates the NCCT (Na+/Cl- co-transporter; SLC12A3) in the kidney and is defective in a rare Mendelian hypertension syndrome (Gordon's syndrome). Genome-wide scans are also being used to look for alleles to predict individual response to antihypertensive drugs and their risk of causing side-effects. The results of these are expected in the near future and may finally deliver the long-awaited goal of personalized drug therapy for hypertensive patients