7,363 research outputs found
Isochoric thermal conductivity of solid nitrogen
The isochoric thermal conductivity of solid nitrogen has been investigated on
four samples of different densities in the temperature interval from 20 K to
the onset of melting. In alfa-N2 the isochoric thermal conductivity exhibits a
dependence weaker than 1/T; in beta-N2 it increases slightly with temperature.
The experimental results are discussed within a model in which the heat is
transported by low-frequency phonons or by "diffusive" modes above the mobility
boundary. The growth of the thermal conductivity in beta-N2 is attributed to
the decreasing "rotational" component of the total thermal resistance, which
occurs as the rotational correlations between the neighboring molecules become
weaker.Comment: Postscript 12 pages, 3 figures, 1 table. To be published in 200
On the Analysis of Chemical Composition of Moon's Surface by Direct Methods
Proportional counter for X ray emission detection and chemical analysis of lunar surface element
Revision of Agraptocoris Reuter (Heteroptera: Miridae: Phylinae), with description of five new species and a review of aedeagal terminology
The predominantly Central Asian genus Agraptocoris Reuter is revised. Eight valid species are recognized, five of those being described as new to science, namely A. eugeniae, A. nigrisetosus, A. pallescens, A. subconcolor (all Mongolia), and A. pamiricus (Tajikistan and Kyrgyzstan). A phylogenetic analysis based on 37 morphological characters is presented for all Agraptocoris species and 13 outgroup taxa. This analysis establishes Agraptocoris as monophyletic and rendered the subtribes Phylina and Oncotylina as non-monophyletic. The differential diagnosis for the genus and a key to all species are given. Habitus photographs, illustrations of male genitalic structures, scanning micrographs of morphological structures, host and distributional information are provided for all species. Homologies and terminology of the aedeagal structures in the subfamily Phylinae are discussed
A New Computationally Simple Approach for Implementing Neural Networks with Output Hard Constraints
A new computationally simple method of imposing hard convex constraints on
the neural network output values is proposed. The key idea behind the method is
to map a vector of hidden parameters of the network to a point that is
guaranteed to be inside the feasible set defined by a set of constraints. The
mapping is implemented by the additional neural network layer with constraints
for output. The proposed method is simply extended to the case when constraints
are imposed not only on the output vectors, but also on joint constraints
depending on inputs. The projection approach to imposing constraints on outputs
can simply be implemented in the framework of the proposed method. It is shown
how to incorporate different types of constraints into the proposed method,
including linear and quadratic constraints, equality constraints, and dynamic
constraints, constraints in the form of boundaries. An important feature of the
method is its computational simplicity. Complexities of the forward pass of the
proposed neural network layer by linear and quadratic constraints are O(n*m)
and O(n^2*m), respectively, where n is the number of variables, m is the number
of constraints. Numerical experiments illustrate the method by solving
optimization and classification problems. The code implementing the method is
publicly available
Causal signal transmission by quantum fields. IV: The causal Wick theorem
Wick's theorem in the Schwinger-Perel-Keldysh closed-time-loop formalism is
written in a form where the place of contractions is taken by the linear
response function of the field. This result demonstrates that the physical
information supplied by Wick's theorem for operators is propagation of the free
field in space and time.Comment: Final version, to appear in Phys Rev
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