Extended Hubbard model for mesoscopic transport in donor arrays in silicon

Arrays of dopants in silicon are promising platforms for the quantum simulation of the Fermi-Hubbard model. We show that the simplest model with only on-site interaction is insufficient to describe the physics of an array of phosphorous donors in silicon due to the strong intersite interaction in the system. We also study the resonant tunneling transport in the array at low temperature as a mean of probing the features of the Hubbard physics, such as the Hubbard bands and the Mott gap. Two mechanisms of localization which suppresses transport in the array are investigated: The first arises from the electron-ion core attraction and is significant at low filling; the second is due to the sharp oscillation in the tunnel coupling caused by the intervalley interference of the donor electron's wavefunction. This disorder in the tunnel coupling leads to a steep exponential decay of conductance with channel length in one-dimensional arrays, but its effect is less prominent in two-dimensional ones. Hence, it is possible to observe resonant tunneling transport in a relatively large array in two dimensions

"It Is Not Good For Man To Be Alone" The Struggle against Loneliness in Old Age: Basic Assumptions for an Integrative Operational Concept –The Israeli Case

The widespread expression saying that "loneliness is the No. 1 enemy of old age" has, in the 21st century, becomes obvious and banal now that suicide rates among the elderly in many countries and in Israel, the case study for this paper, is higher than among other age groups in those countries.Loneliness itself, its ramifications, consequences, and implications on the lives of the elderly have made it a dominant factor in terms of its potential damage.Old age and loneliness have been the subjects of many different definitions, studies and theories, but despite the quantity and quality of these attempts worldwide, and particularly in Israeli research, there is a conspicuous lack of any comprehensive plan that would address the implications and destructive effects of the loneliness experienced by the elderly. Many limited-scale programs exist on a local level, but they fail to address the clear need to eradicate menacing loneliness.The authors of this essay plan to outline basic principles for designing an operational concept for a national plan to combat the consequences and effects of depression among the elderly, using Israel as an example.This paper will begin with a review of the definitions and literature on the phenomenon of depression, and a review of the literature dealing with the unhealthy connection between old age and depression. We will then review various programs worldwide that deal with the phenomenon of loneliness and old age; continue to present data on the effects of loneliness on elderly Israelis; present various Israeli programs and projects that attempt to deal with this phenomenon; and conclude by detailing the proposed principles for a comprehensive operational approach that maps out this painful phenomenon in Israel and proposes a plan of action on how to best deal with it

Topological phases of a dimerized Fermi-Hubbard model for semiconductor nano-lattices

Motivated by recent advances in fabricating artificial lattices in semiconductors and their promise for quantum simulation of topological materials, we study the one-dimensional dimerized Fermi-Hubbard model. We show how the topological phases at half-filling can be characterized by a reduced Zak phase defined based on the reduced density matrix of each spin subsystem. Signatures of bulk-boundary correspondence are observed in the triplon excitation of the bulk and the edge states of uncoupled spins at the boundaries. At quarter-filling we show that owing to the presence of the Hubbard interaction the system can undergo a transition to the topological ground state of the non-interacting Su-Schrieffer-Heeger model with the application of a moderate-strength external magnetic field. We propose a robust experimental realization with a chain of dopant atoms in silicon or gate-defined quantum dots in GaAs where the transition can be probed by measuring the tunneling current through the many-body state of the chain.Comment: 11 pages, 7 figure

The Diversity of REcent and Ancient huMan (DREAM): a new microarray for genetic anthropology and genealogy, forensics, and personalized medicine

The human population displays wide variety in demographic history, ancestry, content of DNA derived from hominins or ancient populations, adaptation, traits, copy number variation (CNVs), drug response, and more. These polymorphisms are of broad interest to population geneticists, forensics investigators, and medical professionals. Historically, much of that knowledge was gained from population survey projects. While many commercial arrays exist for genome-wide single-nucleotide polymorphism (SNP) genotyping, their design specifications are limited and they do not allow a full exploration of biodiversity. We thereby aimed to design the Diversity of REcent and Ancient huMan (DREAM) - an all-inclusive microarray that would allow both identification of known associations and exploration of standing questions in genetic anthropology, forensics, and personalized medicine. DREAM includes probes to interrogate ancestry informative markers obtained from over 450 human populations, over 200 ancient genomes, and 10 archaic hominins. DREAM can identify 94% and 61% of all known Y and mitochondrial haplogroups, respectively and was vetted to avoid interrogation of clinically relevant markers. To demonstrate its capabilities, we compared its FST distributions with those of the 1000 Genomes Project and commercial arrays. Although all arrays yielded similarly shaped (inverse J) FST distributions, DREAM's autosomal and X-chromosomal distributions had the highest mean FST, attesting to its ability to discern subpopulations. DREAM performances are further illustrated in biogeographical, identical by descent (IBD), and CNV analyses. In summary, with approximately 800,000 markers spanning nearly 2,000 genes, DREAM is a useful tool for genetic anthropology, forensic, and personalized medicine studies

2D-3D crossover in a dense electron liquid in silicon

Doping of silicon via phosphene exposures alternating with molecular beam epitaxy overgrowth is a path to Si:P substrates for conventional microelectronics and quantum information technologies. The technique also provides a new and well-controlled material for systematic studies of two-dimensional lattices with a half-filled band. We show here that for a dense ($n_s=2.8\times 10^{14}$\,cm$^{-2}$) disordered two-dimensional array of P atoms, the full field angle-dependent magnetostransport is remarkably well described by classic weak localization theory with no corrections due to interaction effects. The two- to three-dimensional cross-over seen upon warming can also be interpreted using scaling concepts, developed for anistropic three-dimensional materials, which work remarkably except when the applied fields are nearly parallel to the conducting planes.Comment: 9 pages, 4 figures, supplementary informatio

Genome-wide association identifies nine common variants associated with fasting proinsulin levels and provides new insights into the pathophysiology of type 2 diabetes.

OBJECTIVE: Proinsulin is a precursor of mature insulin and C-peptide. Higher circulating proinsulin levels are associated with impaired β-cell function, raised glucose levels, insulin resistance, and type 2 diabetes (T2D). Studies of the insulin processing pathway could provide new insights about T2D pathophysiology. RESEARCH DESIGN AND METHODS: We have conducted a meta-analysis of genome-wide association tests of ∼2.5 million genotyped or imputed single nucleotide polymorphisms (SNPs) and fasting proinsulin levels in 10,701 nondiabetic adults of European ancestry, with follow-up of 23 loci in up to 16,378 individuals, using additive genetic models adjusted for age, sex, fasting insulin, and study-specific covariates. RESULTS: Nine SNPs at eight loci were associated with proinsulin levels (P < 5 × 10(-8)). Two loci (LARP6 and SGSM2) have not been previously related to metabolic traits, one (MADD) has been associated with fasting glucose, one (PCSK1) has been implicated in obesity, and four (TCF7L2, SLC30A8, VPS13C/C2CD4A/B, and ARAP1, formerly CENTD2) increase T2D risk. The proinsulin-raising allele of ARAP1 was associated with a lower fasting glucose (P = 1.7 × 10(-4)), improved β-cell function (P = 1.1 × 10(-5)), and lower risk of T2D (odds ratio 0.88; P = 7.8 × 10(-6)). Notably, PCSK1 encodes the protein prohormone convertase 1/3, the first enzyme in the insulin processing pathway. A genotype score composed of the nine proinsulin-raising alleles was not associated with coronary disease in two large case-control datasets. CONCLUSIONS: We have identified nine genetic variants associated with fasting proinsulin. Our findings illuminate the biology underlying glucose homeostasis and T2D development in humans and argue against a direct role of proinsulin in coronary artery disease pathogenesis

How Less Alienation Creates More Exploitation? Audience Labour on Social Network Sites.

Abstract: The notion of audience labour has been an important contribution to Marxist political economy of the media. It revised the traditional political economy analysis, which focused on media ownership, by suggesting that media was also a site of production, constituting particular relations of production. Such analysis highlighted the active role of audience in the creation of media value as both commodities and workers, thus pointing to audience exploitation. Recently, in light of paradigmatic transformations in the media environment – particularly the emergence of Web 2.0 and social network sites – there has been a renewed interest in such analysis, and a reexamination of audience exploitation. Focusing on Facebook as a case-study, this article examines audience labour on social network sites along two Marxist themes – exploitation and alienation. It argues for a historical shift in the link between exploitation and alienation of audience labour, concurrent with the shift from mass media to social media. In the mass media, the capacity for exploitation of audience labour was quite limited while the alienation that such work created was high. In contrast, social media allows for the expansion and intensification of exploitation. Simultaneously, audience labour on social media – because it involves communication and sociability – also ameliorates alienation by allowing self-expression, authenticity, and relations with others. Moreover, the article argues that the political economy of social network sites is founded on a dialectical link between exploitation and alienation: in order to be de-alienated, Facebook users must communicate and socialize, thus exacerbating their exploitation. And vice-versa, in order for Facebook to exploit the work of its users, it must contribute to their de-alienation

Topological phases of a dimerized Fermi-Hubbard model for semiconductor nano-lattices

Motivated by recent advances in fabricating artificial lattices in semiconductors and their promise for quantum simulation of topological materials, we study the one-dimensional dimerized Fermi- Hubbard model. We show how the topological phases at half-filling can be characterized by a reduced Zak phase defined based on the reduced density matrix of each spin subsystem. Signatures of bulk-boundary correspondence are observed in the triplon excitation of the bulk and the edge states of uncoupled spins at the boundaries. At quarter-filling we show that owing to the presence of the Hubbard interaction the system can undergo a transition to the topological ground state of the non-interacting Su-Schrieffer-Heeger model with the application of a moderate-strength external magnetic field. We propose a robust experimental realization with a chain of dopant atoms in silicon or gate-defined quantum dots in GaAs where the transition can be probed by measuring the tunneling current through the many-body state of the chain