Imaging Inter-Edge State Scattering Centers in the Quantum Hall Regime

We use an atomic force microscope tip as a local gate to study the scattering between edge channels in a 2D electron gas in the quantum Hall regime. The scattering is dominated by individual, microscopic scattering centers, which we directly image here for the first time. The tip voltage dependence of the scattering indicates that tunneling occurs through weak links and localized states.Comment: 4 pages, 5 figure

Control of T lymphocyte morphology by the GTPase Rho

BACKGROUND: Rho family GTPase regulation of the actin cytoskeleton governs a variety of cell responses. In this report, we have analyzed the role of the GTPase Rho in maintenance of the T lymphocyte actin cytoskeleton. RESULTS: Inactivation of the GTPase Rho in the human T lymphocytic cell line HPB-ALL does not inhibit constitutively high adhesion to the integrin β1 substrate fibronectin. It did however result in the aberrant extension of finger-like dendritic processes on the substrates VCAM-1, Fn, and mAb specific to β1 integrins. Time-lapse video microscopy demonstrated that C3 induced extensions were primarily the result of an altered pseudopod elongation rather than retraction. Once the stellate pseudopodia extended, none retracted, and cells became completely immobile. Filipodial structures were absent and the dendritic-like processes in C3 treated cells were rich in filamentous actin. Immunolocalization of RhoA in untreated HPB-ALL cells spreading on fibronectin demonstrated a diffuse staining pattern within the pseudopodia. In C3 treated cells, clusters of RhoA were pronounced and localized within the altered extensions. CONCLUSIONS: GTPase Rho is actively involved in the regulation of T lymphocyte morphology and motility

Scanned Potential Microscopy of Edge and Bulk Currents in the Quantum Hall Regime

Using an atomic force microscope as a local voltmeter, we measure the Hall voltage profile in a 2D electron gas in the quantum Hall (QH) regime. We observe a linear profile in the bulk of the sample in the transition regions between QH plateaus and a distinctly nonlinear profile on the plateaus. In addition, localized voltage drops are observed at the sample edges in the transition regions. We interpret these results in terms of theories of edge and bulk currents in the QH regime.Comment: 4 pages, 5 figure

Evidence for the role of EPHX2 gene variants in anorexia nervosa.

Anorexia nervosa (AN) and related eating disorders are complex, multifactorial neuropsychiatric conditions with likely rare and common genetic and environmental determinants. To identify genetic variants associated with AN, we pursued a series of sequencing and genotyping studies focusing on the coding regions and upstream sequence of 152 candidate genes in a total of 1205 AN cases and 1948 controls. We identified individual variant associations in the Estrogen Receptor-ß (ESR2) gene, as well as a set of rare and common variants in the Epoxide Hydrolase 2 (EPHX2) gene, in an initial sequencing study of 261 early-onset severe AN cases and 73 controls (P=0.0004). The association of EPHX2 variants was further delineated in: (1) a pooling-based replication study involving an additional 500 AN patients and 500 controls (replication set P=0.00000016); (2) single-locus studies in a cohort of 386 previously genotyped broadly defined AN cases and 295 female population controls from the Bogalusa Heart Study (BHS) and a cohort of 58 individuals with self-reported eating disturbances and 851 controls (combined smallest single locus P<0.01). As EPHX2 is known to influence cholesterol metabolism, and AN is often associated with elevated cholesterol levels, we also investigated the association of EPHX2 variants and longitudinal body mass index (BMI) and cholesterol in BHS female and male subjects (N=229) and found evidence for a modifying effect of a subset of variants on the relationship between cholesterol and BMI (P<0.01). These findings suggest a novel association of gene variants within EPHX2 to susceptibility to AN and provide a foundation for future study of this important yet poorly understood condition

Survival Factors for Subcontractors in Economic Downturns

This paper analyzes key issues facing subcontractors in the context of a severe economic crisis, aiming to detect the factors that are critical for the survival of the subcontractors. While previous research efforts have analyzed factors related to subcontractor performance in regular financial conditions, there remains only sparse knowledge of how subcontractors are to survive when economic conditions become dire as they have in recent times in the Spanish construction market. In this research, in-depth interviews with managers of relevant Spanish subcontracting companies were carried out, resulting in the identification of eight factors for subcontractor survival: project delivery method, demand, financial capital, relationship assets, managerial assets, human assets, legal framework, and geographic scope. The project delivery method used by the owner and also by the main contractor is mainly based on price. As a result, the subcontractors bids get lower, making them unsustainable in the long run. Furthermore, subcontractors do not get financial support from banks easily in order to cover their additional financial costs. These facts push subcontractors to get a guarantee of payment by the main contractor, while subcontracting companies may even ask for payments in advance. Subcontractors also seek long-term relationships with the contractor. These trusting relations are very often a prerequisite to qualify and bid for contracts. Subcontractors have to continuously improve, plan ahead and adapt quickly to the new environment. Therefore, subcontractors must remain flexible and maintain a lean hierarchical organization. Doing so makes it is easier for subcontractors to compete in both their native markets, as well as abroad. To this end, the most successful subcontractors have become international during the expansion phase of the economic cycle; many of them went abroad with the help of a contractor from their home country.This research was partially supported by Santander Universidades (Becas Iberoamerica Jovenes Profesionales e Investigadores 2012) that funded a visitorship for Ricardo Oviedo-Haito. The authors are also indebted to all the participants in this research, as well as to Dr. Debra Westall and Dr. Nathaniel Sobin for revising the manuscript. Finally, the valuable commentaries and suggestions of three anonymous reviewers are also highly appreciated.Oviedo-Haito, R.; Jiménez Ayala, J.; Cardoso, F.; Pellicer Armiñana, E. (2014). Survival Factors for Subcontractors in Economic Downturns. Journal of Construction Engineering and Management. 140(3):40130501-40130510. doi:10.1061/(ASCE)CO.1943-7862.0000811S4013050140130510140

"Oh! What a tangled web we weave": Englishness, communicative leisure, identity work and the cultural web of the English folk morris dance scene

In this paper, we consider the relationship between Englishness and the English folk morris dance scene, considering how the latter draws from and reinforces the former. Englishness is considered within the context of the cultural web; a tool more often applied to business management but linked to a sociological viewpoint here. By doing so, we draw the connections between this structured business model and the cultural identity of Englishness. Then, we use the framework of the cultural web and theories of leisure, culture and identity to understand how morris dancers see their role as dancers and ‘communicative leisure’ agents in consciously defending Englishness, English traditions and inventions, the practices and traditions of folk and morris, and the various symbolic communities they inhabit. We argue that most morris dancers in our research become and maintain their leisured identities as dancers because they are attracted to the idea of tradition – even if that tradition is invented and open to change

Combining vitamin C and carotenoid biomarkers better predicts fruit and vegetable intake than individual biomarkers in dietary intervention studies.

The aim of this study was to determine whether combining potential biomarkers of fruit and vegetables is better at predicting FV intake within FV intervention studies than single biomarkers