Conductance distributions in disordered quantum spin-Hall systems

We study numerically the charge conductance distributions of disordered quantum spin-Hall (QSH) systems using a quantum network model. We have found that the conductance distribution at the metal-QSH insulator transition is clearly different from that at the metal-ordinary insulator transition. Thus the critical conductance distribution is sensitive not only to the boundary condition but also to the presence of edge states in the adjacent insulating phase. We have also calculated the point-contact conductance. Even when the two-terminal conductance is approximately quantized, we find large fluctuations in the point-contact conductance. Furthermore, we have found a semi-circular relation between the average of the point-contact conductance and its fluctuation.Comment: 9 pages, 17 figures, published versio

Magnetic-Field Dependence of the Localization Length in Anderson Insulators

Using the conventional scaling approach as well as the renormalization group analysis in $d=2+\epsilon$ dimensions, we calculate the localization length $\xi(B)$ in the presence of a magnetic field $B$. For the quasi 1D case the results are consistent with a universal increase of $\xi(B)$ by a numerical factor when the magnetic field is in the range \ell\ll{\ell_{\!{_H}}}\alt\xi(0), $\ell$ is the mean free path, ${\ell_{\!{_H}}}$ is the magnetic length $\sqrt{\hbar c/eB}$. However, for $d\ge 2$ where the magnetic field does cause delocalization there is no universal relation between $\xi(B)$ and $\xi(0)$. The effect of spin-orbit interaction is briefly considered as well.Comment: 4 pages, revtex, no figures; to be published in Europhysics Letter

Spectral form factor in a random matrix theory

In the theory of disordered systems the spectral form factor $S(\tau)$, the Fourier transform of the two-level correlation function with respect to the difference of energies, is linear for $\tau<\tau_c$ and constant for $\tau>\tau_c$. Near zero and near $\tau_c$ its exhibits oscillations which have been discussed in several recent papers. In the problems of mesoscopic fluctuations and quantum chaos a comparison is often made with random matrix theory. It turns out that, even in the simplest Gaussian unitary ensemble, these oscilllations have not yet been studied there. For random matrices, the two-level correlation function $\rho(\lambda_1,\lambda_2)$ exhibits several well-known universal properties in the large N limit. Its Fourier transform is linear as a consequence of the short distance universality of $\rho(\lambda_1,\lambda_2)$. However the cross-over near zero and $\tau_c$ requires to study these correlations for finite N. For this purpose we use an exact contour-integral representation of the two-level correlation function which allows us to characterize these cross-over oscillatory properties. The method is also extended to the time-dependent case.Comment: 36P, (+5 figures not included

Spectral Density of the QCD Dirac Operator near Zero Virtuality

We investigate the spectral properties of a random matrix model, which in the large $N$ limit, embodies the essentials of the QCD partition function at low energy. The exact spectral density and its pair correlation function are derived for an arbitrary number of flavors and zero topological charge. Their microscopic limit provide the master formulae for sum rules for the inverse powers of the eigenvalues of the QCD Dirac operator as recently discussed by Leutwyler and Smilga.Comment: 9 pages + 1 figure, SUNY-NTG-93/

Efficacy and toxicity outcomes for patients treated with focal salvage high dose rate brachytherapy for locally recurrent prostate cancer

Introduction Isolated local recurrence of prostate cancer following primary radiotherapy or brachytherapy may be treated with focal salvage high dose rate brachytherapy, although there remains an absence of high quality evidence to support this approach. Methods Men with prostate cancer treated consecutively between 2015 and 2018 using 19 Gy in a single fraction high dose rate brachytherapy (HDR) for locally recurrent prostate cancer were identified from an institutional database. Univariable analysis was performed to evaluate the relationship between patient, disease and treatment factors with biochemical progression free survival (bPFS). Results 43 patients were eligible for evaluation. Median follow up duration was 26 months (range 1–60). Median bPFS was 35 months (95% confidence interval 25.6–44.4). Kaplan-Meier estimates for bPFS at 1, 2 and 3 years post salvage were 95.2%, 70.6% and 41.8% respectively. On univariable Cox regression analysis, only nadir PSA was significantly associated with bPFS although the majority of patients were also treated with androgen deprivation therapy. Only one late grade 3 genitourinary toxicity was observed. Conclusion Focal salvage HDR brachytherapy may provide good biochemical control with a low risk of severe toxicity. Further evaluation within clinical trials are needed to establish its role in the management of locally recurrent prostate cancer

Investigating the role of early low-dose aspirin in diabetes: A phase III multicentre double-blinded placebo-controlled randomised trial of aspirin therapy initiated in the first trimester of diabetes pregnancy

Background: Preeclampsia, preterm birth and low birth weight represent key contributing factors to perinatal morbidity and mortality. Pregnancies complicated by type 1 and type 2 diabetes are at increased risk of these complications, which are purported to be largely attributed to placental dysfunction. Studies investigating a potential role for aspirin therapy in optimizing perinatal outcome have consistently failed to demonstrate a benefit among women with pre-existing diabetes, and yet widespread aspirin administration has become common practice in many centres. This study seeks to examine the effect of aspirin therapy, administered from the first trimester until 36 weeks gestation, on perinatal outcome in women with established pre-pregnancy diabetes. Our hypothesis is that aspirin therapy will reduce complications mediated by placental dysfunction, and improve perinatal outcomes. Methods: This phase III double-blinded, placebo-controlled randomized clinical trial will be conducted in seven tertiary-level perinatology centres in Ireland. Consenting participants who meet all eligibility criteria will be allocated randomly to either aspirin 150 mg once daily or matching placebo, commenced between 11 + 0 and 13 + 6 weeks. Allocation will take place electronically using software by Clininfo with randomization tables provided by the trial biostatistician. The primary outcome will be a composite clinical measure of placental dysfunction (preeclampsia, preterm birth before 34 weeks, birthweight below the 10th centile or perinatal mortality). This trial has been set up such that it is parallel in design and is a superiority study. No participants have been recruited yet. The trial has been registered with Eudra Clinical Trials - EudraCT Number 2018-000770-29. Funding for this trial was granted by the Health research Board (HRB) 1/9/2017(DIFA-2017-026). Discussion: Aspirin therapy has been investigated for the prevention of preeclampsia owing to its reduction on thromboxane production. Previous studies have failed to demonstrate a beneficial effect of aspirin on perinatal outcome amongst women with type I or type II diabetes. It is plausible that the failure to observe benefit to date, among the limited aspirin studies that have included participants with diabetes, may be a consequence of aspirin initiation too late in pregnancy to exert any effect on placentation. We believe that if aspirin is to be used for the prevention of placental dysfunction, it must be initiated before the second active phase of trophoblast invasion, which takes place from 14 weeks’ gestation onwards. No randomized trials investigating the role of aspirin in prevention of preeclampsia in pregnancies complicated by diabetes have previously initiated treatment in the first trimester, the gestational period at which it is most likely to exert an effect on placentation

Scaling Theory of Conduction Through a Normal-Superconductor Microbridge

The length dependence is computed of the resistance of a disordered normal-metal wire attached to a superconductor. The scaling of the transmission eigenvalue distribution with length is obtained exactly in the metallic limit, by a transformation onto the isobaric flow of a two-dimensional ideal fluid. The resistance has a minimum for lengths near l/Gamma, with l the mean free path and Gamma the transmittance of the superconductor interface.Comment: 8 pages, REVTeX-3.0, 3 postscript figures appended as self-extracting archive, INLO-PUB-94031

Resistivity of a Metal between the Boltzmann Transport Regime and the Anderson Transition

We study the transport properties of a finite three dimensional disordered conductor, for both weak and strong scattering on impurities, employing the real-space Green function technique and related Landauer-type formula. The dirty metal is described by a nearest neighbor tight-binding Hamiltonian with a single s-orbital per site and random on-site potential (Anderson model). We compute exactly the zero-temperature conductance of a finite size sample placed between two semi-infinite disorder-free leads. The resistivity is found from the coefficient of linear scaling of the disorder averaged resistance with sample length. This ``quantum'' resistivity is compared to the semiclassical Boltzmann expression computed in both Born approximation and multiple scattering approximation.Comment: 5 pages, 3 embedded EPS figure

Monomeric C-reactive protein: a novel biomarker predicting neurodegenerative disease and vascular dysfunction

Circulating C-reactive protein (pCRP) concentrations rise dramatically during both acute (e.g., following stroke) or chronic infection and disease (e.g., autoimmune conditions such as lupus), providing complement fixation through C1q protein binding. It is now known, that on exposure to the membranes of activated immune cells (and microvesicles and platelets), or damaged/dysfunctional tissue, it undergoes lysophosphocholine (LPC)-phospholipase-C-dependent dissociation to the monomeric form (mCRP), concomitantly becoming biologically active. We review histological, immunohistochemical, and morphological/topological studies of post-mortem brain tissue from individuals with neuroinflammatory disease, showing that mCRP becomes stably distributed within the parenchyma, and resident in the arterial intima and lumen, being “released” from damaged, hemorrhagic vessels into the extracellular matrix. The possible de novo synthesis via neurons, endothelial cells, and glia is also considered. In vitro, in vivo, and human tissue co-localization analyses have linked mCRP to neurovascular dysfunction, vascular activation resulting in increased permeability, and leakage, compromise of blood brain barrier function, buildup of toxic proteins including tau and beta amyloid (Aβ), association with and capacity to “manufacture” Aβ-mCRP-hybrid plaques, and, greater susceptibility to neurodegeneration and dementia. Recently, several studies linked chronic CRP/mCRP systemic expression in autoimmune disease with increased risk of dementia and the mechanisms through which this occurs are investigated here. The neurovascular unit mediates correct intramural periarterial drainage, evidence is provided here that suggests a critical impact of mCRP on neurovascular elements that could suggest its participation in the earliest stages of dysfunction and conclude that further investigation is warranted. We discuss future therapeutic options aimed at inhibiting the pCRP-LPC mediated dissociation associated with brain pathology, for example, compound 1,6-bis-PC, injected intravenously, prevented mCRP deposition and associated damage, after temporary left anterior descending artery ligation and myocardial infarction in a rat model