5,964 research outputs found
Bitcoin Crypto - bounties for quantum capable adversaries
With the advances in quantum computing taking place over the last few years, researchers have started considering the implications on cryptocurrencies. As most digital signature schemes would be impacted, it is somewhat reassuring that transition schemes to quantum resistant signatures are already being considered for Bitcoin. In this work, we stress the danger of public key reuse, as it prevents users from recovering their funds in the presence of a quantum enabled adversary despite any transition scheme the developers decide to implement. We emphasize this threat by quantifying the damage a functional quantum computer could inflict on Bitcoin (and Bitcoin Cash) by breaking exposed public keys
Sampling constrained probability distributions using Spherical Augmentation
Statistical models with constrained probability distributions are abundant in
machine learning. Some examples include regression models with norm constraints
(e.g., Lasso), probit, many copula models, and latent Dirichlet allocation
(LDA). Bayesian inference involving probability distributions confined to
constrained domains could be quite challenging for commonly used sampling
algorithms. In this paper, we propose a novel augmentation technique that
handles a wide range of constraints by mapping the constrained domain to a
sphere in the augmented space. By moving freely on the surface of this sphere,
sampling algorithms handle constraints implicitly and generate proposals that
remain within boundaries when mapped back to the original space. Our proposed
method, called {Spherical Augmentation}, provides a mathematically natural and
computationally efficient framework for sampling from constrained probability
distributions. We show the advantages of our method over state-of-the-art
sampling algorithms, such as exact Hamiltonian Monte Carlo, using several
examples including truncated Gaussian distributions, Bayesian Lasso, Bayesian
bridge regression, reconstruction of quantized stationary Gaussian process, and
LDA for topic modeling.Comment: 41 pages, 13 figure
Evidence for CP Violation in B0 -> D+D- Decays
We report measurements of the branching fraction and CP violation parameters
in B0 -> D+D- decays. The results are based on a data sample that contains 535
x 10^6 BBbar pairs collected at the Upsilon(4S) resonance, with the Belle
detector at the KEKB asymmetric-energy e+e- collider. We obtain [1.97 +- 0.20
(stat) +- 0.20 (syst)] x 10^(-4) for the branching fraction of B0 -> D+D-. The
measured values of the CP violation parameters are: S = -1.13 +- 0.37 +- 0.09,
A = 0.91 +- 0.23 +- 0.06, where the first error is statistical and the second
is systematic. We find evidence of CP violation in B0 -> D+D- at the 4.1 sigma
confidence level. While the value of S is consistent with expectations from
other measurements, the value of the parameter A favors large direct CP
violation at the 3.2 sigma confidence level, in contradiction to Standard Model
expectations.Comment: 12 pages, 3 figures, submitted to PR
A flexible stand-alone testbench for characterizing the front-end electronics for the CMS preshower detector under LHC-like timing conditions
Search for the h_c meson in B^+- ->h_c K^+-
We report a search for the meson via the decay chain , \etac \gamma with and
. No significant signals are observed. We obtain upper limits on the
branching fractions for in bins of the
invariant mass. The results are based on an analysis of 253
fb of data collected by the Belle detector at the KEKB
collider.Comment: 12 pages, 6 figures, submitted to Phys. Rev.
Search for Resonant Decays at Belle
We report measurements and searches for resonant decays where is a
meson or
the X(3872) particle.Comment: accepted by Physics Letters
Statistical properties of contact vectors
We study the statistical properties of contact vectors, a construct to
characterize a protein's structure. The contact vector of an N-residue protein
is a list of N integers n_i, representing the number of residues in contact
with residue i. We study analytically (at mean-field level) and numerically the
amount of structural information contained in a contact vector. Analytical
calculations reveal that a large variance in the contact numbers reduces the
degeneracy of the mapping between contact vectors and structures. Exact
enumeration for lengths up to N=16 on the three dimensional cubic lattice
indicates that the growth rate of number of contact vectors as a function of N
is only 3% less than that for contact maps. In particular, for compact
structures we present numerical evidence that, practically, each contact vector
corresponds to only a handful of structures. We discuss how this information
can be used for better structure prediction.Comment: 20 pages, 6 figure
Study of time-dependent CP violation in B0 -> J/Psi pi0 decays
We report a measurement of CP asymmetry parameters in the decay B0(B0bar) ->
J/Psi pi0, which is governed by the b->c cbar d transition. The analysis is
based on a 140/fb data sample accumulated at the Upsilon(4S) resonance by the
belle detector at the KEKB asymmetric-energy e+e- collider. We fully
reconstruct one neutral B meson in the J/Psi pi0 final state. The accompanying
B meson flavor is identified by its decay products. From the distribution of
proper time intervals between the two B decays, we obtain the following
CP-violating parameters: S_{J/Psi pi0}=-0.72+-0.42+-0.09 and A_{J/Psi
pi0}=-0.01 +-0.29+-0.03.Comment: 5 pages, 2 figures, submitted to PR
A CLASP-modulated cell edge barrier mechanism drives cell-wide cortical microtubule organization in Arabidopsis
It is well known that the parallel order of microtubules in the plant cell cortex defines the direction of cell expansion, yet it remains unclear how microtubule orientation is controlled, especially on a cell-wide basis. Here we show through 4D imaging and computational modelling that plant cell polyhedral geometry provides spatial input that determines array orientation and heterogeneity. Microtubules depolymerize when encountering sharp cell edges head-on, whereas those oriented parallel to those sharp edges remain. Edge-induced microtubule depolymerization, however, is overcome by the microtubule-associated protein CLASP, which accumulates at specific cell edges, enables microtubule growth around sharp edges and promotes formation of microtubule bundles that span adjacent cell faces. By computationally modelling dynamic 'microtubules on a cube' with edges differentially permissive to microtubule passage, we show that the CLASP-edge complex is a 'tuneable' microtubule organizer, with the inherent flexibility to generate the numerous cortical array patterns observed in nature
Improved Measurements of Branching Fractions and CP Asymmetries in B-> eta h Decays
We report improved measurements of B decays with an eta meson in the final
state using 492 fb^{-1} of data collected by the Belle detector at the KEKB e^+
e^- collider. We observe the decays B^{+-}-> eta pi^{+-} and B^{+-}-> eta
K^{+-}; the measured branching fractions are Br(B^{+-}-> eta pi^{+-}) = (4.2+-
0.4(stat)+- 0.2(sys))x10^{-6} and Br(B^{+-}-> eta K^{+-}) =
(1.9+-0.3(stat)^{+0.2}_{-0.1}(sys))x10^{-6}. The corresponding CP-violating
asymmetries are measured to be -0.23+- 0.09(stat) +-0.02(sys) for eta pi^{+-}
and -0.39+-0.16(stat)+-0.03(sys) for eta K^{+-}. We also search for B^0-> eta
K^0 decays and set an upper limit of 1.9x10^{-6} at the 90% confidence level.Comment: 7 pages, 3 figure
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