283 research outputs found

    Quantum phase transition triggering magnetic BICs in graphene

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    Graphene hosting a pair of collinear adatoms in the phantom atom configuration has pseudogap with cubic scaling on energy, Δε3\Delta\propto|\varepsilon|^{3} which leads to the appearance of spin-degenerate bound states in the continuum (BICs) [Phys. Rev. B 92, 045409 (2015)]. In the case when adatoms are locally coupled to a single carbon atom the pseudogap scales linearly with energy, which prevents the formation of BICs. In this Letter, we explore the effects of non-local coupling characterized by the Fano factor of interference q0,q_{0}, tunable by changing the slope of the Dirac cones in the graphene band-structure. We demonstrate that three distinct regimes can be identified: i) for q0<qc1q_{0}<q_{c1} (critical point) a mixed pseudogap Δε,ε2\Delta\propto|\varepsilon|,|\varepsilon|^{2} appears yielding a phase with spin-degenerate BICs; ii) near q0=qc1q_{0}=q_{c1} when Δε2\Delta\propto|\varepsilon|^{2} the system undergoes a quantum phase transition in which the new phase is characterized by magnetic BICs and iii) at a second critical value q0>qc2q_{0}>q_{c2} the cubic scaling of the pseudogap with energy Δε3\Delta\propto|\varepsilon|^{3} characteristic to the phantom atom configuration is restored and the phase with non-magnetic BICs is recovered. The phase with magnetic BICs can be described in terms of an effective intrinsic exchange field of ferromagnetic nature between the adatoms mediated by graphene monolayer. We thus propose a new type of quantum phase transition resulting from the competition between the states characterized by spin-degenerate and magnetic BICs

    Catching the Bound States in the Continuum of a Phantom Atom in Graphene

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    We explore theoretically the formation of bound states in the continuum (BICs) in graphene hosting two collinear adatoms situated at different sides of the sheet and at the center of the hexagonal cell, where a phantom atom of a fictitious lattice emulates the six carbons of the cell. We verify that in this configuration the local density of states (LDOS) near the Dirac points exhibits two characteristic features: i) the cubic dependence on energy instead of the linear one for graphene as found in New J. Phys. 16, 013045 (2014) and ii) formation of BICs as aftermath of a Fano destructive interference assisted by the Coulomb correlations in the adatoms. For the geometry where adatoms are collinear to carbon atoms, we report absence of BICs

    Familial aggregation of lymphoplasmacytic lymphoma/Waldenström macroglobulinemia with solid tumors and myeloid malignancies.

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    To access publisher full text version of this article. Please click on the hyperlink in Additional Links field.Lymphoplasmacytic lymphoma (LPL)/Waldenström macroglobulinemia (WM) is a B-cell disorder resulting from the accumulation, predominantly in the bone marrow, of clonally related lymphoplasmacytic cells. LPL/WM is a very rare disease, with an incidence rate of 3-4 cases per million people per year.Currently, the causes of LPL/WM are poorly understood; however, there are emerging data to support a role for immune-related factors in the pathogenesis of LPL/WM. In addition, data show that genetic factors are of importance in the etiology of LPL/WM. In this paper, we will review the current knowledge about familiality of LPL/WM and provide novel data on solid tumors and myeloid malignancies in first-degree relatives of LPL/WM patients.Swedish Cancer Society Stockholm County Council Karolinska Institutet Foundations National Institutes of Health, National Cancer Institute Roch

    The impact of prior malignancies on second malignancies and survival in MM patients: a population-based study

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    To access publisher's full text version of this article, please click on the hyperlink in Additional Links field or click on the hyperlink at the top of the page marked FilesIn the present study, we aimed to evaluate 2 hypotheses. First, we hypothesize that prior malignancy is a proxy for genetic susceptibility that could be a risk factor for subsequent malignancy development in multiple myeloma (MM) patients. Second, we hypothesize that survival after MM is influenced by a prior malignancy. All patients diagnosed with MM from 1 January 1973 to 31 December 2010 were identified from the Swedish Cancer Register. Cox regression model was used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) where prior malignancy was compared in MM patients who developed a subsequent malignancy and MM patients who did not. In another Cox regression model, survival was compared in MM patients with and without a prior malignancy diagnosis. A total of 19 791 patients were diagnosed with MM. Patients with a prior malignancy diagnosis had a significantly increased risk of developing a subsequent malignancy compared with MM patients without (HR 1.42, 95% CI 1.23-1.65, P 1 prior malignancy reduces survival even further.Asrun Einarsdottir Foundation in Iceland Blodcancerfonden Swedish Cancer Society Stockholm County Council Karolinska Institutet Foundation University of Iceland Research Fund Icelandic Centre for Research Landspitali University Hospital Research Fund Marie Curie Career Integration Grant Memorial Sloan Kettering Cancer Center Core Grant by the National Cancer Institute, National Institutes of Healt

    Thrombosis is associated with inferior survival in multiple myeloma

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    Germline and somatic JAK2 mutations and susceptibility to chronic myeloproliferative neoplasms

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    Myeloproliferative neoplasms (MPNs) are a group of closely related stem-cell-derived clonal proliferative diseases. Most cases are sporadic but first-degree relatives of MPN patients have a five- to seven-fold increased risk for developing an MPN. The tumors of most patients carry a mutation in the Janus kinase 2 gene (JAK2V617F). Recently, three groups have described a strong association of JAK2 germline polymorphisms with MPN in patients positive for JAK2V617F. The somatic mutation occurs primarily on one particular germline JAK2 haplotype, which may account for as much as 50% of the risk to first-degree relatives. This finding provides new directions for unraveling the pathogenesis of MPN

    On the possibility of a terahertz light emitting diode based on a dressed quantum well

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    We consider theoretically the realization of a tunable terahertz light emitting diode from a quantum well with dressed electrons placed in a highly doped p-n junction. In the considered system the strong resonant dressing field forms dynamic Stark gaps in the valence and conduction bands and the electric field inside the p-n junction makes the QW asymmetric. It is shown that the electrons transiting through the light induced Stark gaps in the conduction band emit photons with energy directly proportional to the dressing field. This scheme is tunable, compact, and shows a fair efficiency.Comment: 6 pages, 5 figure

    The ambivalence of losing weight after bariatric surgery

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    This study is grounded in a phenomenological lifeworld perspective. It aims at providing rich descriptions of lived experience of the process of losing weight after obesity surgery. Two women participated in in-depth interviews four times each during the first postoperative year. Based on the women's experiences, a meaning structure—the ambivalence of losing weight after obesity surgery—was identified across the women's processes of change. This consisted of five core themes: movement and activity—freedom but new demands and old restraints; eating habits and digestion—the complexity of change; appearance—smaller, but looser; social relations—stability and change; and being oneself—vulnerability and self-assurance. These core themes changed over time in terms of dominance. The experience of ambivalence is discussed according to a phenomenological perspective of the body as lived experience

    Success or failure of primary second/foreign language programmes in Asia: What do the data tell us?

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    Primary school second/foreign language (SL/FL) programmes in Asia, as well as in other parts of the world, are becoming more common, with many targeting English as the SL or FL. The pressures for such English language programmes come from top-down notions that in a globalised world English is required for societies to be competitive, especially with Asian neighbours, and bottom-up pressures from parents who see English as the key to educational success for their children. In many polities, these forces have resulted in support for policies that introduce early primary school English teaching curricula for all students and have led to parents spending large sums of money on private tutoring or out-of-school tuition. This study reviews the results of nine language planning studies from the Asian region that set out to examine questions such as 'Is this trend towards early primary SL or FL education (mainly English) realistic or is it unattainable and a waste of resources? Do children really benefit from these programmes? What needs to be done to foster learners' success?' These issues are viewed from a language planning and policy perspective through an examination of the language-in-education policy types required for the development of successful programmes. The policies of a number of Asian countries are used as case studies to illustrate this issue

    Modeling Historic Rangeland Management and Grazing Pressures in Landscapes of Settlement

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    Defining historic grazing pressures and rangeland management is vital if early landscape threshold crossing and long–term trajectories of landscape change are to be properly understood. In this paper we use a new environmental simulation model, Búmodel, to assess two contrasting historical grazing landscapes in Mývatnssveit Iceland for two key periods—the colonization period (ca. Landnám, A.D. 872–1000) and the early eighteenth century A.D. Results suggest that there were spatial and temporal variations in productivity and grazing pressure within and between historic grazing areas and indicate that land degradation was not an inevitable consequence of the livestock grazing introduced with settlement. The results also demonstrate the significance of grazing and livestock management strategies in preventing overgrazing, particularly under cooler climatic conditions. The model enables detailed consideration of historic grazing management scenarios and their associated landscape pressures
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