Correlating Atomic Structure and Transport in Suspended Graphene Nanoribbons

Qi, Zhengqing John,Rodrí,guez-Manzo, Julio A.,Botello-Mé,ndez, André,s R.,Hong, Sung Ju,Stach, Eric A.,Park, Yung Woo,Charlier, Jean-Christophe,Drndić,, Marija,Johnson, A. T. Ch American Chemical Society 2014 NANO LETTERS Vol.14 No.8

<P/><P>Graphene nanoribbons (GNRs) are promising candidates for next generation integrated circuit (IC) components; this fact motivates exploration of the relationship between crystallographic structure and transport of graphene patterned at IC-relevant length scales (<10 nm). We report on the controlled fabrication of pristine, freestanding GNRs with widths as small as 0.7 nm, paired with simultaneous lattice-resolution imaging and electrical transport characterization, all conducted within an aberration-corrected transmission electron microscope. Few-layer GNRs very frequently formed bonded-bilayers and were remarkably robust, sustaining currents in excess of 1.5 μA per carbon bond across a 5 atom-wide ribbon. We found that the intrinsic conductance of a sub-10 nm bonded bilayer GNR scaled with width as <I>G</I><SUB>BL</SUB>(<I>w</I>) ≈ 3/4(<I>e</I><SUP>2</SUP><I>/h</I>)<I>w</I>, where <I>w</I> is the width in nanometers, while a monolayer GNR was roughly five times less conductive. Nanosculpted, crystalline monolayer GNRs exhibited armchair-terminated edges after current annealing, presenting a pathway for the controlled fabrication of semiconducting GNRs with known edge geometry. Finally, we report on simulations of quantum transport in GNRs that are in qualitative agreement with the observations.</P>

The pulsating hot subdwarf Balloon 090100001: results of the 2005 multisite campaign

Baran, A.,Oreiro, R.,Pigulski, A.,Herná,ndez, F. Pé,rez,Ulla, A.,Reed, M. D.,Rodrí,guez-Ló,pez, C.,Moskalik, P.,Kim, S.-L.,Chen, W.-P.,Crowe, R.,Siwak, M.,Armendarez, L.,Binder Blackwell Publishing Ltd 2009 MONTHLY NOTICES- ROYAL ASTRONOMICAL SOCIETY Vol.392 No.3

<P>ABSTRACT</P><P>We present the results of a multisite photometric campaign on the pulsating B-type hot subdwarf star Balloon 090100001 (Bal09). The star is one of the two known hybrid hot subdwarfs with both long- and short-period oscillations, theoretically attributed to <I>g</I> and <I>p</I> modes. The campaign involved eight telescopes with three obtaining <I>UBVR</I> data, four <I>B</I>-band data and one Strömgren <I>uvby</I> photometry. The campaign covered 48 nights, providing a temporal resolution of 0.36 μHz with a detection threshold of about 0.2 mmag in <I>B</I>-filter data.</P><P>Bal09 has the richest pulsation spectrum of any known pulsating subdwarf B star, and our analysis detected 114 frequencies including 97 independent and 17 combination ones. Most of the 24 <I>g</I>-mode frequencies are between 0.1 and 0.4 mHz. Of the remaining 73, presumably <I>p</I> modes, 72 group into four distinct regions near 2.8, 3.8, 4.7 and 5.5 mHz. The density of frequencies requires that some modes must have degrees ℓ larger than 2. The modes in the 2.8 mHz region have the largest amplitudes. The strongest mode (<I>f</I><SUB>1</SUB>) is most likely radial, while the remaining ones in this region form two nearly symmetric multiplets: a triplet and quintuplet, attributed to rotationally split ℓ= 1 and 2 modes, respectively. We find clear increases of splitting in both multiplets between the 2004 and 2005 observing campaigns, amounting to ∼15 per cent on average. The observed splittings imply that the rotational rate in Bal09 depends on stellar latitude and is the fastest on the equator. We also speculate on the possible reasons for the changes of splitting. The only plausible explanation we find is torsional oscillation. This hypothesis, however, needs to be verified in the future by detailed modelling. In this context, it is very important to monitor the splittings on a longer time-scale as their behaviour may help to explain this interesting phenomenon.</P><P>The amplitudes of almost all terms detected in both 2004 and 2005 were found to vary. This is evident even during one season; for example, amplitudes of modes <I>f</I><SUB>8</SUB> and <I>f</I><SUB>C</SUB> were found to change by a factor of 2–3 within about 50 d during 2005.</P><P>We use a small grid of models to constrain the main mode (<I>f</I><SUB>1</SUB>), which most likely represents the radial fundamental pulsation. The groups of <I>p</I>-mode frequencies appear to lie in the vicinity of the consecutive radial overtones, up to the third one. Despite the large number of <I>g</I>-mode frequencies observed, we failed to identify them, most likely because of the disruption of asymptotic behaviour by mode trapping. The observed frequencies were not, however, fully exploited in terms of seismic analysis which should be done in the future with a larger grid of reliable evolutionary models of hot subdwarfs.</P>

Common non-synonymous SNPs associated with breast cancer susceptibility: findings from the Breast Cancer Association Consortium

Milne, Roger L.,Burwinkel, Barbara,Michailidou, Kyriaki,Arias-Perez, Jose-Ignacio,Zamora, M. Pilar,Mené,ndez-Rodrí,guez, Primitiva,Hardisson, David,Mendiola, Marta,Gonzá,lez-Neira, A IRL Press 2014 Human molecular genetics Vol.23 No.22

<P>Candidate variant association studies have been largely unsuccessful in identifying common breast cancer susceptibility variants, although most studies have been underpowered to detect associations of a realistic magnitude. We assessed 41 common non-synonymous single-nucleotide polymorphisms (nsSNPs) for which evidence of association with breast cancer risk had been previously reported. Case-control data were combined from 38 studies of white European women (46 450 cases and 42 600 controls) and analyzed using unconditional logistic regression. Strong evidence of association was observed for three nsSNPs: <I>ATXN7-</I>K264R at 3p21 [rs1053338, per allele OR = 1.07, 95% confidence interval (CI) = 1.04–1.10, <I>P</I> = 2.9 × 10<SUP>−6</SUP>], <I>AKAP9-</I>M463I at 7q21 (rs6964587, OR = 1.05, 95% CI = 1.03–1.07, <I>P</I> = 1.7 × 10<SUP>−6</SUP>) and <I>NEK10-</I>L513S at 3p24 (rs10510592, OR = 1.10, 95% CI = 1.07–1.12, <I>P</I> = 5.1 × 10<SUP>−17</SUP>). The first two associations reached genome-wide statistical significance in a combined analysis of available data, including independent data from nine genome-wide association studies (GWASs): for <I>ATXN7-</I>K264R, OR = 1.07 (95% CI = 1.05–1.10, <I>P</I> = 1.0 × 10<SUP>−8</SUP>); for <I>AKAP9-</I>M463I, OR = 1.05 (95% CI = 1.04–1.07, <I>P</I> = 2.0 × 10<SUP>−10</SUP>). Further analysis of other common variants in these two regions suggested that intronic SNPs nearby are more strongly associated with disease risk. We have thus identified a novel susceptibility locus at 3p21, and confirmed previous suggestive evidence that rs6964587 at 7q21 is associated with risk. The third locus, rs10510592, is located in an established breast cancer susceptibility region; the association was substantially attenuated after adjustment for the known GWAS hit. Thus, each of the associated nsSNPs is likely to be a marker for another, non-coding, variant causally related to breast cancer risk. Further fine-mapping and functional studies are required to identify the underlying risk-modifying variants and the genes through which they act.</P>

Shell evolution of <i>N</i> = 40 isotones towards ⁶⁰Ca: First spectroscopy of ⁶²Ti

Corté,s, M.L.,Rodriguez, W.,Doornenbal, P.,Obertelli, A.,Holt, J.D.,Lenzi, S.M.,Mené,ndez, J.,Nowacki, F.,Ogata, K.,Poves, A.,Rodrí,guez, T.R.,Schwenk, A.,Simonis, J.,Stroberg, S.R. North-Holland Pub. Co 2020 Physics letters. Section B Vol.800 No.-

<P><B>Abstract</B></P> <P>Excited states in the N = 40 isotone <SUP>62</SUP>Ti were populated via the <SUP>63</SUP>V ( p , 2 p ) <SUP>62</SUP>Ti reaction at ∼200 MeV/nucleon at the Radioactive Isotope Beam Factory and studied using <I>γ</I>-ray spectroscopy. The energies of the 2 1 + → 0 gs + and 4 1 + → 2 1 + transitions, observed here for the first time, indicate a deformed <SUP>62</SUP>Ti ground state. These energies are increased compared to the neighboring <SUP>64</SUP>Cr and <SUP>66</SUP>Fe isotones, suggesting a small decrease of quadrupole collectivity. The present measurement is well reproduced by large-scale shell-model calculations based on effective interactions, while ab initio and beyond mean-field calculations do not yet reproduce our findings. The shell-model calculations for <SUP>62</SUP>Ti show a dominant configuration with four neutrons excited across the N = 40 gap. Likewise, they indicate that the N = 40 island of inversion extends down to Z = 20 , disfavoring a possible doubly magic character of the elusive <SUP>60</SUP>Ca.</P>