Ab initio prediction of Boron compounds arising from Borozene: Structural and electronic properties

Structure and electronic properties of two unusual boron clusters obtained by fusion of borozene rings has been studied by means of first principles calculations, based on the generalized-gradient approximation of the density functional theory, and the semiempirical tight-binding method was used for the transport calculations. The role of disorder has also been considered with single vacancies and substitutional atoms. Results show that the pure boron clusters are topologically planar and characterized by (3c-2e) bonds, which can explain, together with the aromaticity (estimated by means of NICS), the remarkable cohesive energy values obtained. Such feature makes these systems competitive with the most stable boron clusters to date. On the contrary, the introduction of impurities compromises stability and planarity in both cases. The energy gap values indicate that these clusters possess a semiconducting character, while when the larger system is considered, zero-values of the density of states are found exclusively within the HOMO-LUMO gap. Electron transport calculations within the Landauer formalism confirm these indications, showing semiconductor-like low bias differential conductance for these stuctures. Differences and similarities with Carbon clusters are highlighted in the discussion.Comment: 10 pages, 2 tables, 5 figure

Goldstones in Diphotons

We study the conditions for a new scalar resonance to be observed first in diphotons at the LHC Run-2. We focus on scenarios where the scalar arises either from an internal or spacetime symmetry broken spontaneously, for which the mass is naturally below the cutoff and the low-energy interactions are fixed by the couplings to the broken currents, UV anomalies, and selection rules. We discuss the recent excess in diphoton resonance searches observed by ATLAS and CMS at 750 GeV, and explore its compatibility with other searches at Run-1 and its interpretation as Goldstone bosons in supersymmetry and composite Higgs models. We show that two candidates naturally emerge: a Goldstone boson from an internal symmetry with electromagnetic anomalies, and the scalar partner of the Goldstone of supersymmetry breaking: the sgoldstino. The dilaton from conformal symmetry breaking is instead disfavoured by present data, in its minimal natural realization.Comment: 18 pages + refs, 2 figures. v2: typos corrected, references added, discussions extended and three new plots. Conclusion unchanged. v3: published versio

Change in N-terminal pro-B-type natriuretic peptide at 1 year predicts mortality in wild-type transthyretin amyloid cardiomyopathy

OBJECTIVES: Wild-type transthyretin amyloid cardiomyopathy (wtATTR-CM) is a progressive and fatal condition. Although prognosis can be determined at the time of diagnosis according to National Amyloidosis Centre (NAC) transthyretin amyloidosis (ATTR) stage, the clinical course varies substantially between individuals. There are currently no established measures of rate of disease progression. Through systematic analysis of functional, biochemical and echocardiographic disease-related variables we aimed to identify prognostic markers of disease progression in wtATTR-CM. METHODS: This is a retrospective observational study of 432 patients with wtATTR-CM diagnosed at the UK NAC, none of whom received disease-modifying therapy. The association between mortality from the 12-month timepoint and change from diagnosis to 12 months in a variety of disease-related variables was explored using Cox regression. RESULTS: Change in N-terminal pro-B-type natriuretic peptide concentration (∆ NT-proBNP) at 12 months from diagnosis was the strongest predictor of ongoing mortality and was independent of both change in other disease-related variables (HR 1.04 per 500 ng/L increase (95% CI 1.01 to 1.07); p=0.003) and a range of known prognostic variables at the time of diagnosis (HR 1.07 per 500 ng/L increase (95% CI 1.02 to 1.13); p=0.007). An increase in NT-proBNP of >500 ng/L, >1000 ng/L and >2000 ng/L during the first year of follow-up occurred in 45%, 35% and 16% of patients, respectively. CONCLUSION: Change in NT-proBNP concentration during the first year of follow-up is a powerful independent predictor of mortality in wtATTR-CM

99mTc-DPD scintigraphy in immunoglobulin light chain (AL) cardiac amyloidosis

AIMS: Technetium-99m-labelled 3,3-diphosphono-1,2-propanodicarboxylic acid (99mTc-DPD scintigraphy) is recognized as highly accurate for the non-invasive diagnosis of transthyretin (ATTR) cardiac amyloidosis (CA). A proportion of patients with immunoglobulin light chain (AL) CA have also been reported to show cardiac 99mTc-DPD uptake. Herein, we assessed the frequency and degree of cardiac 99mTc-DPD uptake and its clinical significance among patients with AL CA. METHODS AND RESULTS: Between 2010 and 2017, 292 consecutive patients with AL CA underwent 99mTc-DPD scintigraphy and were included in this study: 114 (39%) had cardiac 99mTc-DPD uptake: grade 1 in 75%, grade 2 in 17%, and grade 3 in 8% of cases. Patients with cardiac 99mTc-DPD uptake had poorer cardiac systolic function and higher N-terminal pro-brain natriuretic peptide. No differences were noted in cardiac magnetic resonance parameters between patients with and without cardiac 99mTc-DPD uptake (N = 19 and 42, respectively). Patients with cardiac 99mTc-DPD uptake showed a trend to worse survival than those with no uptake (log-rank P = 0.056). Among 22 patients who underwent serial 99mTc-DPD scintigraphy, 5 (23%) showed reduction in the grade of cardiac uptake. CONCLUSIONS: In this large cohort of patients with AL CA, 99mTc-DPD scintigraphy ∼40% of cases showed cardiac uptake, including grade 2-3 in 10% of all patients (25% of those with cardiac 99mTc-DPD uptake). Cardiac 99mTc-DPD uptake was associated with poorer cardiac function and outcomes. These data highlight the critical importance of ruling out AL amyloidosis in all patients with cardiac 99mTc-DPD uptake to ensure such patients are not assumed to have ATTR CA

Combining Anomaly and Z' Mediation of Supersymmetry Breaking

We propose a scenario in which the supersymmetry breaking effect mediated by an additional U(1)' is comparable with that of anomaly mediation. We argue that such a scenario can be naturally realized in a large class of models. Combining anomaly with Z' mediation allows us to solve the tachyonic slepton problem of the former and avoid significant fine tuning in the latter. We focus on an NMSSM-like scenario where U(1)' gauge invariance is used to forbid a tree-level mu term, and present concrete models, which admit successful dynamical electroweak symmetry breaking. Gaugino masses are somewhat lighter than the scalar masses, and the third generation squarks are lighter than the first two. In the specific class of models under consideration, the gluino is light since it only receives a contribution from 2-loop anomaly mediation, and it decays dominantly into third generation quarks. Gluino production leads to distinct LHC signals and prospects of early discovery. In addition, there is a relatively light Z', with mass in the range of several TeV. Discovering and studying its properties can reveal important clues about the underlying model.Comment: Minor changes: references added, typos corrected, journal versio

Warped Radion Dark Matter

Warped scenarios offer an appealing solution to the hierarchy problem. We consider a non-trivial deformation of the basic Randall-Sundrum framework that has a KK-parity symmetry. This leads to a stable particle beyond the Standard Model, that is generically expected to be the first KK-parity odd excitation of the radion field. We consider the viability of the KK-radion as a DM candidate in the context of thermal and non-thermal production in the early universe. In the thermal case, the KK-radion can account for the observed DM density when the radion decay constant is in the natural multi-TeV range. We also explore the effects of coannihilations with the first KK excitation of the RH top, as well as the effects of radion-Higgs mixing, which imply mixing between the KK-radion and a KK-Higgs (both being KK-parity odd). The non-thermal scenario, with a high radion decay constant, can also lead to a viable scenario provided the reheat temperature and the radion decay constant take appropriate values, although the reheat temperature should not be much higher than the TeV scale. Direct detection is found to be feasible if the DM has a small (KK-parity odd) Higgs admixture. Indirect detection via a photon signal from the galactic center is an interesting possibility, while the positron and neutrino fluxes from KK-radion annihilations are expected to be rather small. Colliders can probe characteristic aspects of the DM sector of warped scenarios with KK-parity, such as the degeneracy between the radion and the KK-radion (DM) modes.Comment: 43 pages, 16 figures; added reference

Cardiac Magnetic Resonance–Derived Extracellular Volume Mapping for the Quantification of Hepatic and Splenic Amyloid

BACKGROUND: Systemic amyloidosis is characterized by amyloid deposition that can involve virtually any organ. Splenic and hepatic amyloidosis occurs in certain types, in some patients but not others, and may influence prognosis and treatment. SAP (serum amyloid P component) scintigraphy is uniquely able to identify and quantify amyloid in the liver and spleen, thus informing clinical management, but it is only available in 2 centers globally. The aims of this study were to examine the potential for extracellular volume (ECV) mapping performed during routine cardiac magnetic resonance to: (1) detect amyloid in the liver and spleen and (2) estimate amyloid load in these sites using SAP scintigraphy as the reference standard. METHODS: Five hundred thirty-three patients referred to the National Amyloidosis Centre, London, between 2015 and 2017 with suspected systemic amyloidosis who underwent SAP scintigraphy and cardiac magnetic resonance with T1 mapping were studied. RESULTS: The diagnostic performance of ECV to detect splenic and hepatic amyloidosis was high for both organs (liver: area under the curve, -0.917 [95% CI, 0.880-0.954]; liver ECV cutoff, 0.395; sensitivity, 90.7%; specificity, 77.7%; P<0.001; spleen: area under the curve, -0.944 [95% CI, 0.925-0.964]; spleen ECV cutoff, 0.385; sensitivity, 93.6%; specificity, 87.5%; P<0.001). There was good correlation between liver and spleen ECV and amyloid load assessed by SAP scintigraphy (r=0.504, P<0.001; r=0.693, P<0.001, respectively). There was high interobserver agreement for both the liver and spleen (ECV liver intraclass correlation coefficient, 0.991 [95% CI, 0.984-0.995]; P<0.001; ECV spleen intraclass correlation coefficient, 0.995 [95% CI, 0.991-0.997]; P<0.001) with little bias across a wide range of ECV values. CONCLUSIONS: Our study demonstrates that ECV measurements obtained during routine cardiac magnetic resonance scans in patients with suspected amyloidosis can identify and measure the magnitude of amyloid infiltration in the liver and spleen, providing important clues to amyloid type and offering a noninvasive measure of visceral amyloid burden that can help guide and track treatment