Optimizing double-base elliptic-curve single-scalar multiplication

This paper analyzes the best speeds that can be obtained for single-scalar multiplication with variable base point by combining a huge range of options: • many choices of coordinate systems and formulas for individual group operations, including new formulas for tripling on Edwards curves; • double-base chains with many different doubling/tripling ratios, including standard base-2 chains as an extreme case; • many precomputation strategies, going beyond Dimitrov, Imbert, Mishra (Asiacrypt 2005) and Doche and Imbert (Indocrypt 2006). The analysis takes account of speedups such as S – M tradeoffs and includes recent advances such as inverted Edwards coordinates. The main conclusions are as follows. Optimized precomputations and triplings save time for single-scalar multiplication in Jacobian coordinates, Hessian curves, and tripling-oriented Doche/Icart/Kohel curves. However, even faster single-scalar multiplication is possible in Jacobi intersections, Edwards curves, extended Jacobi-quartic coordinates, and inverted Edwards coordinates, thanks to extremely fast doublings and additions; there is no evidence that double-base chains are worthwhile for the fastest curves. Inverted Edwards coordinates are the speed leader

On Exceptional Times for generalized Fleming-Viot Processes with Mutations

If $\mathbf Y$ is a standard Fleming-Viot process with constant mutation rate (in the infinitely many sites model) then it is well known that for each $t>0$ the measure $\mathbf Y_t$ is purely atomic with infinitely many atoms. However, Schmuland proved that there is a critical value for the mutation rate under which almost surely there are exceptional times at which $\mathbf Y$ is a finite sum of weighted Dirac masses. In the present work we discuss the existence of such exceptional times for the generalized Fleming-Viot processes. In the case of Beta-Fleming-Viot processes with index $\alpha\in\,]1,2[$ we show that - irrespectively of the mutation rate and $\alpha$ - the number of atoms is almost surely always infinite. The proof combines a Pitman-Yor type representation with a disintegration formula, Lamperti's transformation for self-similar processes and covering results for Poisson point processes

Numerical study of the directed polymer in a 1+3 dimensional random medium

The directed polymer in a 1+3 dimensional random medium is known to present a disorder-induced phase transition. For a polymer of length $L$, the high temperature phase is characterized by a diffusive behavior for the end-point displacement $R^2 \sim L$ and by free-energy fluctuations of order $\Delta F(L) \sim O(1)$. The low-temperature phase is characterized by an anomalous wandering exponent $R^2/L \sim L^{\omega}$ and by free-energy fluctuations of order $\Delta F(L) \sim L^{\omega}$ where $\omega \sim 0.18$. In this paper, we first study the scaling behavior of various properties to localize the critical temperature $T_c$. Our results concerning $R^2/L$ and $\Delta F(L)$ point towards $0.76 < T_c \leq T_2=0.79$, so our conclusion is that $T_c$ is equal or very close to the upper bound $T_2$ derived by Derrida and coworkers ($T_2$ corresponds to the temperature above which the ratio $\bar{Z_L^2}/(\bar{Z_L})^2$ remains finite as $L \to \infty$). We then present histograms for the free-energy, energy and entropy over disorder samples. For $T \gg T_c$, the free-energy distribution is found to be Gaussian. For $T \ll T_c$, the free-energy distribution coincides with the ground state energy distribution, in agreement with the zero-temperature fixed point picture. Moreover the entropy fluctuations are of order $\Delta S \sim L^{1/2}$ and follow a Gaussian distribution, in agreement with the droplet predictions, where the free-energy term $\Delta F \sim L^{\omega}$ is a near cancellation of energy and entropy contributions of order $L^{1/2}$.Comment: 8 pages, 16 figure

Issues of Processing and Multiple Testing of SELDI-TOF MS Proteomic Data

A new data filtering method for SELDI-TOF MS proteomic spectra data is described. We examined technical repeats (2 per subject) of intensity versus m/z (mass/charge) of bone marrow cell lysate for two groups of childhood leukemia patients: acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL). As others have noted, the type of data processing as well as experimental variability can have a disproportionate impact on the list of interesting proteins (see Baggerly et al. (2004)). We propose a list of processing and multiple testing techniques to correct for 1) background drift; 2) filtering using smooth regression and cross-validated bandwidth selection; 3) peak finding; and 4) methods to correct for multiple testing (van der Laan et al. (2005)). The result is a list of proteins (indexed by m/z) where average expression is significantly different among disease (or treatment, etc.) groups. The procedures are intended to provide a sensible and statistically driven algorithm, which we argue provides a list of proteins that have a significant difference in expression. Given no sources of unmeasured bias (such as confounding of experimental conditions with disease status), proteins found to be statistically significant using this technique have a low probability of being false positives

The 1+1-dimensional Kardar-Parisi-Zhang equation and its universality class

We explain the exact solution of the 1+1 dimensional Kardar-Parisi-Zhang equation with sharp wedge initial conditions. Thereby it is confirmed that the continuum model belongs to the KPZ universality class, not only as regards to scaling exponents but also as regards to the full probability distribution of the height in the long time limit.Comment: Proceedings StatPhys 2

Terahertz radiation driven chiral edge currents in graphene

We observe photocurrents induced in single layer graphene samples by illumination of the graphene edges with circularly polarized terahertz radiation at normal incidence. The photocurrent flows along the sample edges and forms a vortex. Its winding direction reverses by switching the light helicity from left- to right-handed. We demonstrate that the photocurrent stems from the sample edges, which reduce the spatial symmetry and result in an asymmetric scattering of carriers driven by the radiation electric field. The developed theory is in a good agreement with the experiment. We show that the edge photocurrents can be applied for determination of the conductivity type and the momentum scattering time of the charge carriers in the graphene edge vicinity.Comment: 4 pages, 4 figure, additional Supplemental Material (3 pages, 1 figure

Vibrational Spectra of a Mechanosensitive Channel

We report the simulated vibrational spectra of a mechanosensitive membrane channel in different gating states. Our results show that while linear absorption is insensitive to structural differences, linear dichroism and sum-frequency generation spectroscopies are sensitive to the orientation of the transmembrane helices, which is changing during the opening process. Linear dichroism cannot distinguish an intermediate structure from the closed structure, but sum-frequency generation can. In addition, we find that two-dimensional infrared spectroscopy can be used to distinguish all three investigated gating states of the mechanosensitive membrane channel.

Ketamine Dysregulates the Amplitude and Connectivity of High-Frequency Oscillations in Cortical-Subcortical Networks in Humans: Evidence From Resting-State Magnetoencephalography-Recordings

Hypofunctioning of the N-methyl-D-aspartate (NMDA)-receptor (NMDA-R) has been prominently implicated in the pathophysiology of schizophrenia (ScZ). The current study tested the effects of ketamine, a dissociative anesthetic and NMDA-R antagonist, on resting-state activity recorded with magnetoencephalography (MEG) in healthy volunteers. In a single-blind cross-over design, each participant (n = 12) received, on two different sessions, a subanesthetic dose of S-ketamine (0.006 mg/Kg) and saline injection. MEG-data were analyzed at sensorand source- level in the beta (13-30 Hz) and gamma (30-90 Hz) frequency ranges. In addition, connectivity analysis at source-level was performed using transfer entropy (TE). Ketamine increased gamma-power while beta-band activity was decreased. Specifically, elevated 30-90 Hz activity was pronounced in subcortical (thalamus and hippocampus) and cortical (frontal and temporal cortex) regions, whilst reductions in beta-band power were localized to the precuneus, cerebellum, anterior cingulate, temporal and visual cortex. TE analysis demonstrated increased information transfer in a thalamo-cortical network after ketamine administration. The findings are consistent with the pronounced dysregulation of highfrequency oscillations following the inhibition of NMDA-R in animal models of ScZ as well as with evidence from EEG-data in ScZ-patients and increased functional connectivity during early illness stages. Moreover, our data highlight the potential contribution of thalamo-cortical connectivity patterns towards ketamine-induced neuronal dysregulation, which may be relevant for the understanding of schizophrenia as a disorder of disinhibition of neural circuits

Tolerance induction through early feeding to prevent food allergy in infants with eczema (TEFFA): rationale, study design, and methods of a randomized controlled trial

BACKGROUND: Up to 8% of all children in industrialized countries suffer from food allergies, whereas children with atopic eczema are affected considerably more frequently. In addition, the type and starting time of weaning foods seem to influence the development of food allergies. However, data from interventional studies on weaning are controversial. The aim of this randomized-controlled clinical trial is to investigate, whether an early introduction of hen's egg (HE), cow's milk (CM), peanut (PN), and hazelnut (HN) in children with atopic eczema can reduce the risk for developing food allergies in the first year of life. METHODS: This is a protocol for a randomized, placebo controlled, double blind, single-center clinical trial. One hundred fifty infants with atopic eczema at 4-8 months of age will be randomized in a 2:1 manner into an active group that will receive rusk-like biscuit powder with HE, CM, PN, and HN (initially approximately 2 mg of each food protein) for 6-8 months or a placebo group, whose participants will receive the same rusk-like biscuit powder without HE, CM, PN, and HN on a daily basis. During the interventional period, the amount of allergens in the study product will be increased three times, each after 6 weeks. All study participants who are sensitized to HE, CM, PN, or HN at the end of the interventional period will undergo an oral food challenge to the respective food in a further visit. Primary endpoint is IgE-mediated food allergy to at least one of the four foods (HE, CM, PN or HN) after 6-8 months of intervention (i.e., at around 1 year of age). Secondary endpoints include multiple food allergies, severity of eczema, wheezing, and sensitization levels against food allergens. DISCUSSION: This clinical trial will assess whether an early introduction of allergenic foods into the diet of children with atopic eczema can prevent the development of food allergies. This trial will contribute to update food allergy prevention guidelines. TRIAL REGISTRATION: German Clinical Trials Register DRKS00016770 . Registered on 09 January 2020