Unforeseen high temperature and humidity stability of FeCl3 intercalated few layer graphene

This is the final version of the article. Available from the publisher via the DOI in this record.We present the first systematic study of the stability of the structure and electrical properties of FeCl3 intercalated few-layer graphene to high levels of humidity and high temperature. Complementary experimental techniques such as electrical transport, high resolution transmission electron microscopy and Raman spectroscopy conclusively demonstrate the unforseen stability of this transparent conductor to a relative humidity up to 100% at room temperature for 25 days, to a temperature up to 150°C in atmosphere and to a temperature as high as 620°C in vacuum, that is more than twice higher than the temperature at which the intercalation is conducted. The stability of FeCl3 intercalated few-layer graphene together with its unique values of low square resistance and high optical transparency, makes this material an attractive transparent conductor in future flexible electronic applications

Holographic dual of the Eguchi-Kawai mechanism

archiveprefix: arXiv primaryclass: hep-th reportnumber: NORDITA-2014-40, UUITP-03-14, QMUL-PH-14-08 slaccitation: %%CITATION = ARXIV:1404.0225;%%archiveprefix: arXiv primaryclass: hep-th reportnumber: NORDITA-2014-40, UUITP-03-14, QMUL-PH-14-08 slaccitation: %%CITATION = ARXIV:1404.0225;%%archiveprefix: arXiv primaryclass: hep-th reportnumber: NORDITA-2014-40, UUITP-03-14, QMUL-PH-14-08 slaccitation: %%CITATION = ARXIV:1404.0225;%%The work of K.Z. was supported by the ERC advanced grant No 341222, by the Marie Curie network GATIS of the European Union’s FP7 Programme under REA Grant Agreement No 317089, and by the Swedish Research Council (VR) grant 2013-4329. DY acknowledges NORDITA where this work was begun, during his time as a NORDITA fellow

Gluon Scattering Amplitudes in Finite Temperature Gauge/Gravity Dualities

We examine the gluon scattering amplitude in N=4 super Yang-Mills at finite temperature with nonzero R-charge densities, and in Non-Commutative gauge theory at finite temperature. The gluon scattering amplitude is defined as a light-like Wilson loop which lives at the horizon of the T-dual black holes of the backgrounds we consider. We study in detail a special amplitude, which corresponds to forward scattering of a low energy gluon off a high energy one. For this kinematic configuration in the considered backgrounds, we find the corresponding minimal surface which is directly related to the gluon scattering amplitude. We find that for increasing the chemical potential or the non-commutative parameter, the on-shell action corresponding to our Wilson loop in the T-dual space decreases. For all of our solutions the length of the short side of the Wilson loop is constrained by an upper bound which depends on the temperature, the R-charge density and the non-commutative parameter. Due to this constraint, in the limit of zeroth temperature our approach breaks down since the upper bound goes to zero, while by keeping the temperature finite and letting the chemical potential or the non-commutative parameter to approach to zero the limit is smooth.Comment: 30 pages, 16 figures, minor corrections (plus improved numerical computation for the non-commutative case

Clinical presentation of strokes confined to the insula: a systematic review of literature

BACKGROUND AND PURPOSE: The insular cortex serves a wide variety of functions in humans, ranging from sensory and affective processing to high-level cognition. Hence, insular dysfunction may result in several different presentations. Ischemic strokes limited to the insular territory are rare and deserve a better characterization, to be quickly recognized and to receive the appropriate treatment (e.g. thrombolysis). METHODS: We reviewed studies on patients with a first-ever acute stroke restricted to the insula. We searched in the Medline database the keywords "insular stroke" and "insular infarction", to identify previously published cases. Afterwards, the results were divided depending on the specific insular region affected by the stroke: anterior insular cortex (AIC), posterior insular cortex (PIC) or total insula cortex (TIC). Finally, a review of the clinical correlates associated with each region was performed. RESULTS: We identified 25 reports including a total of 49 patients (59.7 ± 15.5 years, 48% male) from systematic review of the literature. The most common clinical phenotypes were motor and somatosensory deficits, dysarthria, aphasia and a vestibular-like syndrome. Atypical presentations were also common and included dysphagia, awareness deficits, gustatory disturbances, dysautonomia, neuropsychiatric or auditory disturbances and headache. CONCLUSIONS: The clinical presentation of insular strokes is heterogeneous; however, an insular stroke should be suspected when vestibular-like, somatosensory, speech or language disturbances are combined in the same patient. Further studies are needed to improve our understanding of more atypical presentations

Phases of planar 5-dimensional supersymmetric Chern-Simons theory

In this paper we investigate the large-$N$ behavior of 5-dimensional $\mathcal{N}=1$ super Yang-Mills with a level $k$ Chern-Simons term and an adjoint hypermultiplet. As in three-dimensional Chern-Simons theories, one must choose an integration contour to completely define the theory. Using localization, we reduce the path integral to a matrix model with a cubic action and compute its free energy in various scenarios. In the limit of infinite Yang-Mills coupling and for particular choices of the contours, we find that the free-energy scales as $N^{5/2}$ for $U(N)$ gauge groups with large values of the Chern-Simons 't\,Hooft coupling, $\tilde\lambda\equiv N/k$. If we also set the hypermultiplet mass to zero, then this limit is a superconformal fixed point and the $N^{5/2}$ behavior parallels other fixed points which have known supergravity duals. We also demonstrate that $SU(N)$ gauge groups cannot have this $N^{5/2}$ scaling for their free-energy. At finite Yang-Mills coupling we establish the existence of a third order phase transition where the theory crosses over from the Yang-Mills phase to the Chern-Simons phase. The phase transition exists for any value of $\tilde\lambda$, although the details differ between small and large values of $\tilde\lambda$. For pure Chern-Simons theories we present evidence for a chain of phase transitions as $\tilde\lambda$ is increased. We also find the expectation values for supersymmetric circular Wilson loops in these various scenarios and show that the Chern-Simons term leads to different physical properties for fundamental and anti-fundamental Wilson loops. Different choices of the integration contours also lead to different properties for the loops.Comment: 40 pages, 17 figures, Minor corrections, Published versio

Premenopausal endogenous oestrogen levels and breast cancer risk: a meta-analysis.

BACKGROUND: Many of the established risk factors for breast cancer implicate circulating hormone levels in the aetiology of the disease. Increased levels of postmenopausal endogenous oestradiol (E2) have been found to increase the risk of breast cancer, but no such association has been confirmed in premenopausal women. We carried out a meta-analysis to summarise the available evidence in women before the menopause. METHODS: We identified seven prospective studies of premenopausal endogenous E2 and breast cancer risk, including 693 breast cancer cases. From each study we extracted odds ratios of breast cancer between quantiles of endogenous E2, or for unit or s.d. increases in (log transformed) E2, or (where odds ratios were unavailable) summary statistics for the distributions of E2 in breast cancer cases and unaffected controls. Estimates for a doubling of endogenous E2 were obtained from these extracted estimates, and random-effect meta-analysis was used to obtain a pooled estimate across the studies. RESULTS: Overall, we found weak evidence of a positive association between circulating E2 levels and the risk of breast cancer, with a doubling of E2 associated with an odds ratio of 1.10 (95% CI: 0.96, 1.27). CONCLUSION: Our findings are consistent with the hypothesis of a positive association between premenopausal endogenous E2 and breast cancer risk

M2-M5 blackfold funnels

We analyze the basic M2-M5 intersection in the supergravity regime using the blackfold approach. This approach allows us to recover the 1/4-BPS self-dual string soliton solution of Howe, Lambert and West as a three-funnel solution of an effective fivebrane worldvolume theory in a new regime, the regime of a large number of M2 and M5 branes. In addition, it allows us to discuss finite temperature effects for non-extremal self-dual string soliton solutions and wormhole solutions interpolating between stacks of M5 and anti-M5 branes. The purpose of this paper is to exhibit these solutions and their basic properties.Comment: 19 pages, 5 figures, harvmac; typo corrected in equation (3.19

On stable higher spin states in Heterotic String Theories

We study properties of 1/2 BPS Higher Spin states in heterotic compactifications with extended supersymmetry. We also analyze non BPS Higher Spin states and give explicit expressions for physical vertex operators of the first two massive levels. We then study on-shell tri-linear couplings of these Higher Spin states and confirm that BPS states with arbitrary spin cannot decay into lower spin states in perturbation theory. Finally, we consider scattering of vector bosons off higher spin BPS states and extract form factors and polarization effects in various limits.Comment: 38 page

Imaging spontaneous currents in superconducting arrays of pi-junctions

Superconductors separated by a thin tunneling barrier exhibit the Josephson effect that allows charge transport at zero voltage, typically with no phase shift between the superconductors in the lowest energy state. Recently, Josephson junctions with ground state phase shifts of pi proposed by theory three decades ago have been demonstrated. In superconducting loops, pi-junctions cause spontaneous circulation of persistent currents in zero magnetic field, analogous to spin-1/2 systems. Here we image the spontaneous zero-field currents in superconducting networks of temperature-controlled pi-junctions with weakly ferromagnetic barriers using a scanning SQUID microscope. We find an onset of spontaneous supercurrents at the 0-pi transition temperature of the junctions Tpi = 3 K. We image the currents in non-uniformly frustrated arrays consisting of cells with even and odd numbers of pi-junctions. Such arrays are attractive model systems for studying the exotic phases of the 2D XY-model and achieving scalable adiabatic quantum computers.Comment: Pre-referee version. Accepted to Nature Physic