On open quantum systems, effective Hamiltonians and device characterization

High fidelity models, which support accurate device characterization and correctly account for environmental effects, are crucial to the engineering of scalable quantum technologies. As it ensures positivity of the density matrix, one preferred model for open systems describes the dynamics with a master equation in Lindblad form. The Linblad operators are rarely derived from first principles, resulting in dynamical models which miss those additional terms that must generally be added to bring the master equation into Lindblad form, together with concomitant other terms that must be assimilated into an effective Hamiltonian. In first principles derivations such additional terms are often cancelled (countered), frequently in an ad hoc manner. In the case of a Superconducting Quantum Interference Device (SQUID) coupled to an Ohmic bath, the resulting master equation implies the environment has a significant impact on the system's energy. We discuss the prospect of keeping or cancelling this impact; and note that, for the SQUID, measuring the magnetic susceptibility under control of the capacitive coupling strength and the externally applied flux, results in experimentally measurable differences between models. If this is not done correctly, device characterization will be prone to systemic errors.Comment: 5 pages, 3 figure

SECOND INTERNATIONAL SYMPOSIUM ON RANAVIRUSES:: A NORTH AMERICAN HERPETOLOGICAL PERSPECTIVE

Ranaviruses are large double stranded DNA viruses of poikilothermic vertebrates including amphibians, reptiles and fish. In North America, ranaviral disease and ranavirus-related die-off events have been documented in all three classes. Ranaviruses are found worldwide, appear to be emerging in some regions, and are increasingly recognized as a threat to many species

On infinite-finite duality pairs of directed graphs

The (A,D) duality pairs play crucial role in the theory of general relational structures and in the Constraint Satisfaction Problem. The case where both classes are finite is fully characterized. The case when both side are infinite seems to be very complex. It is also known that no finite-infinite duality pair is possible if we make the additional restriction that both classes are antichains. In this paper (which is the first one of a series) we start the detailed study of the infinite-finite case. Here we concentrate on directed graphs. We prove some elementary properties of the infinite-finite duality pairs, including lower and upper bounds on the size of D, and show that the elements of A must be equivalent to forests if A is an antichain. Then we construct instructive examples, where the elements of A are paths or trees. Note that the existence of infinite-finite antichain dualities was not previously known

THIRD INTERNATIONAL SYMPOSIUM ON RANAVIRUSES:: ADVANCING THE UNDERSTANDING OF THE THREAT OF RANAVIRUSES TO NORTH AMERICAN HERPETOFAUNA

Members of the genus Ranavirus, one of five genera withinthe family Iridoviridae, encompass a group of large, doublestrandedDNA viruses that infect all three classes of ectothermicvertebrates: fish, amphibians, and reptiles. Ranaviruses areglobally emerging pathogens that cause considerable morbidityand mortality among diverse populations. In North America,ranavirus epizootics are regularly reported in wild and culturedfish, amphibian, and reptile populations

Covering Partial Cubes with Zones

A partial cube is a graph having an isometric embedding in a hypercube. Partial cubes are characterized by a natural equivalence relation on the edges, whose classes are called zones. The number of zones determines the minimal dimension of a hypercube in which the graph can be embedded. We consider the problem of covering the vertices of a partial cube with the minimum number of zones. The problem admits several special cases, among which are the problem of covering the cells of a line arrangement with a minimum number of lines, and the problem of finding a minimum-size fibre in a bipartite poset. For several such special cases, we give upper and lower bounds on the minimum size of a covering by zones. We also consider the computational complexity of those problems, and establish some hardness results

Hitting all Maximal Independent Sets of a Bipartite Graph

We prove that given a bipartite graph G with vertex set V and an integer k, deciding whether there exists a subset of V of size k hitting all maximal independent sets of G is complete for the class Sigma_2^P.Comment: v3: minor chang

On 1-factorizations of Bipartite Kneser Graphs

It is a challenging open problem to construct an explicit 1-factorization of the bipartite Kneser graph $H(v,t)$, which contains as vertices all $t$-element and $(v-t)$-element subsets of $[v]:=\{1,\ldots,v\}$ and an edge between any two vertices when one is a subset of the other. In this paper, we propose a new framework for designing such 1-factorizations, by which we solve a nontrivial case where $t=2$ and $v$ is an odd prime power. We also revisit two classic constructions for the case $v=2t+1$ --- the \emph{lexical factorization} and \emph{modular factorization}. We provide their simplified definitions and study their inner structures. As a result, an optimal algorithm is designed for computing the lexical factorizations. (An analogous algorithm for the modular factorization is trivial.)Comment: We design the first explicit 1-factorization of H(2,q), where q is a odd prime powe

Emerging infectious disease threats to European herpetofauna

In the past decade, infectious disease threats to European herpetofauna have become better understood. Since the 1990s, three major emerging infections in amphibians have been identified (Batrachochytrium dendrobatidis, B. salamandrivorans, and ranaviruses) as well as at least one of unknown status (herpesviruses), while two major emerging infections of reptiles (Ophidiomyces ophiodiicola and ranaviruses) have been identified in wild European populations. The effects of emerging infections on populations have ranged from non-existent to local extirpation. In this article, we review these major infectious disease threats to European herpetofauna, including descriptions of key mortality and/or morbidity events in Europe of their emergence, and address both the distribution and the host diversity of the agent. Additionally, we direct the reader to newly developed resources that facilitate the study of infectious agents in herpetofauna and again stress the importance of an interdisciplinary approach to examining these infectious diseases

Gene Expression Pattern Analysis of Anterior Hox Genes during Zebrafish (Danio rerio) Embryonic Development Reveals Divergent Expression Patterns from Other Teleosts

The regional identity of organs and organ systems along the anterior-posterior axis during embryonic development is patterned, in part, by Hox genes, which encode transcription factor proteins that activate or repress the expression of downstream target genes. Divergent nested Hox gene expression patterns may have had a role in facilitating morphological divergence of structures, such as the pharyngeal jaw apparatus, among evolutionarily divergent teleost fishes. Recent studies from several evolutionarily divergent teleosts, such as the Japanese Medaka (Oryzias latipes) and the Nile Tilapia (Oreochromis niloticus), have shown the presence of divergent expression patterns of several Hox genes within paralog groups 2–5 between these species. Specifically, these expression patterns were documented in the pharyngeal arches, which give rise to the pharyngeal jaw apparatus. While the expression patterns of several Zebrafish (Danio rerio) Hox genes that are orthologous to those of Medaka and Tilapia have been documented within the developing hindbrain and pharyngeal arches, many still have yet to be documented, especially within the pharyngeal arches during the postmigratory cranial neural crest cell stages. Here, we present the expression patterns of six Zebrafish Hox genes, hoxc3a, d3a, a4a, d4a, b5a, and c5a, within the pharyngeal arches during a postmigratory cranial neural crest cell stage and compare them to their orthologous genes of Medaka and Tilapia at similar stages. We show that while hoxc3a, d3a, and c5a of Zebrafish are absent from the pharyngeal arches, hoxa4a, d4a, and b5a show divergent expression patterns from their orthologs in Medaka and Tilapia. These observed divergences may be, in part, responsible for the divergent pharyngeal jaw apparatus structures exhibited by these fishes