2,555 research outputs found
Measurement of 139La(p,x) cross sections from 35–60 MeV by stacked-target activation
A stacked-target of natural lanthanum foils (99.9119% 139La) was irradiated using a 60 MeV proton beam at the LBNL 88-Inch Cyclotron. 139La(p,x) cross sections are reported between 35–60 MeV for nine product radionuclides. The primary motivation for this measurement was the need to quantify the production of 134Ce. As a positron-emitting analogue of the promising medical radionuclide 225Ac, 134Ce is desirable for in vivo applications of bio-distribution assays for this emerging radio-pharmaceutical. The results of this measurement were compared to the nuclear model codes TALYS, EMPIRE and ALICE (using default parameters), which showed significant deviation from the measured values
Energy Dependence of the Delta Resonance: Chiral Dynamics in Action
There is an important connection between the low energy theorems of QCD and
the energy dependence of the Delta resonance in pi-N scattering, as well as the
closely related gamma^{*} N -> pi N reaction. The resonance shape is due not
only to the strong pi-N interaction in the p wave but the small interaction in
the s wave; the latter is due to spontaneous chiral symmetry breaking in QCD
(i.e. the Nambu-Goldstone nature of the pion). A brief overview of experimental
tests of chiral perturbation theory and chiral based models is presentedComment: 11 pages, 6 figures, Festschrift for S.N. yan
The Jacobian Conjecture 2n implies the Dixmier Problem n
The aim of the paper is to describe some ideas, approaches, comments, etc. regarding the Dixmier Conjecture, its generalizations and analogues
Extra-gastrointestinal manifestations of inflammatory bowel disease may be less common than previously reported
Extra-intestinal manifestations are well recognized in inflammatory bowel disease (IBD). To what extent the commonly recognized extra-intestinal manifestations seen in IBD patients are attributable to IBD is, however, not clear due to the limited number of controlled studies published
Age-related differences in adaptation during childhood: The influences of muscular power production and segmental energy flow caused by muscles
Acquisition of skillfulness is not only characterized by a task-appropriate application of muscular forces but also by the ability to adapt performance to changing task demands. Previous research suggests that there is a different developmental schedule for adaptation at the kinematic compared to the neuro-muscular level. The purpose of this study was to determine how age-related differences in neuro-muscular organization affect the mechanical construction of pedaling at different levels of the task. By quantifying the flow of segmental energy caused by muscles, we determined the muscular synergies that construct the movement outcome across movement speeds. Younger children (5-7 years; n = 11), older children (8-10 years; n = 8), and adults (22-31 years; n = 8) rode a stationary ergometer at five discrete cadences (60, 75, 90, 105, and 120 rpm) at 10% of their individually predicted peak power output. Using a forward dynamics simulation, we determined the muscular contributions to crank power, as well as muscular power delivered to the crank directly and indirectly (through energy absorption and transfer) during the downstroke and the upstroke of the crank cycle. We found significant age × cadence interactions for (1) peak muscular power at the hip joint [Wilks' Lambda = 0.441, F(8,42) = 2.65, p = 0.019] indicating that at high movement speeds children produced less peak power at the hip than adults, (2) muscular power delivered to the crank during the downstroke and the upstroke of the crank cycle [Wilks' Lambda = 0.399, F(8,42) = 3.07, p = 0.009] indicating that children delivered a greater proportion of the power to the crank during the upstroke when compared to adults, (3) hip power contribution to limb power [Wilks' Lambda = 0.454, F(8,42) = 2.54, p = 0.023] indicating a cadence-dependence of age-related differences in the muscular synergy between hip extensors and plantarflexors. The results demonstrate that in spite of a successful performance, children construct the task of pedaling differently when compared to adults, especially when they are pushed to their performance limits. The weaker synergy between hip extensors and plantarflexors suggests that a lack of inter-muscular coordination, rather than muscular power production per se, is a factor that limits children's performance ranges
Chosen-ciphertext security from subset sum
We construct a public-key encryption (PKE) scheme whose
security is polynomial-time equivalent to the hardness of the Subset Sum problem. Our scheme achieves the standard notion of indistinguishability against chosen-ciphertext attacks (IND-CCA) and can be used to encrypt messages of arbitrary polynomial length, improving upon a previous construction by Lyubashevsky, Palacio, and Segev (TCC 2010) which achieved only the weaker notion of semantic security (IND-CPA) and whose concrete security decreases with the length of the message being encrypted. At the core of our construction is a trapdoor technique which originates in the work of Micciancio and Peikert (Eurocrypt 2012
An Improved BKW Algorithm for LWE with Applications to Cryptography and Lattices
In this paper, we study the Learning With Errors problem and its binary
variant, where secrets and errors are binary or taken in a small interval. We
introduce a new variant of the Blum, Kalai and Wasserman algorithm, relying on
a quantization step that generalizes and fine-tunes modulus switching. In
general this new technique yields a significant gain in the constant in front
of the exponent in the overall complexity. We illustrate this by solving p
within half a day a LWE instance with dimension n = 128, modulus ,
Gaussian noise and binary secret, using
samples, while the previous best result based on BKW claims a time
complexity of with samples for the same parameters. We then
introduce variants of BDD, GapSVP and UniqueSVP, where the target point is
required to lie in the fundamental parallelepiped, and show how the previous
algorithm is able to solve these variants in subexponential time. Moreover, we
also show how the previous algorithm can be used to solve the BinaryLWE problem
with n samples in subexponential time . This
analysis does not require any heuristic assumption, contrary to other algebraic
approaches; instead, it uses a variant of an idea by Lyubashevsky to generate
many samples from a small number of samples. This makes it possible to
asymptotically and heuristically break the NTRU cryptosystem in subexponential
time (without contradicting its security assumption). We are also able to solve
subset sum problems in subexponential time for density , which is of
independent interest: for such density, the previous best algorithm requires
exponential time. As a direct application, we can solve in subexponential time
the parameters of a cryptosystem based on this problem proposed at TCC 2010.Comment: CRYPTO 201
The cultural construction of subject discipline knowledge: comparing ‘abstraction’ in two international contexts
On the Schoenberg Transformations in Data Analysis: Theory and Illustrations
The class of Schoenberg transformations, embedding Euclidean distances into
higher dimensional Euclidean spaces, is presented, and derived from theorems on
positive definite and conditionally negative definite matrices. Original
results on the arc lengths, angles and curvature of the transformations are
proposed, and visualized on artificial data sets by classical multidimensional
scaling. A simple distance-based discriminant algorithm illustrates the theory,
intimately connected to the Gaussian kernels of Machine Learning
The Proteomic Code: a molecular recognition code for proteins
<p>Abstract</p> <p>Background</p> <p>The Proteomic Code is a set of rules by which information in genetic material is transferred into the physico-chemical properties of amino acids. It determines how individual amino acids interact with each other during folding and in specific protein-protein interactions. The Proteomic Code is part of the redundant Genetic Code.</p> <p>Review</p> <p>The 25-year-old history of this concept is reviewed from the first independent suggestions by Biro and Mekler, through the works of Blalock, Root-Bernstein, Siemion, Miller and others, followed by the discovery of a Common Periodic Table of Codons and Nucleic Acids in 2003 and culminating in the recent conceptualization of partial complementary coding of interacting amino acids as well as the theory of the nucleic acid-assisted protein folding.</p> <p>Methods and conclusions</p> <p>A novel cloning method for the design and production of specific, high-affinity-reacting proteins (SHARP) is presented. This method is based on the concept of proteomic codes and is suitable for large-scale, industrial production of specifically interacting peptides.</p
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