735 research outputs found
Local unitary invariants for multipartite quantum systems
A method is presented to obtain local unitary invariants for multipartite
quantum systems consisting of fermions or distinguishable particles. The
invariants are organized into infinite families, in particular, the
generalization to higher dimensional single particle Hilbert spaces is
straightforward. Many well-known invariants and their generalizations are also
included.Comment: 13 page
Water quality monitoring: a ‘toolbox’ in response to the EU’s Water Framework Directive requirements
Investigating the temporal trends in PAH, PCB and OCP concentrations in Hartbeespoort Dam, South Africa, using semipermeable membrane devices (SPMDs)
The seasonal variability of persistent organic pollutants in Hartbeespoort Dam, South Africa, was investigated using semipermeable membrane devices (SPMDs) as passive samplers. Freely dissolved waterborne polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) were sampled to investigate seasonal changes in their concentrations. Exposure of the passive samplers was done for 14 days at the same sampling site in each of the four seasons of the year, in 2011. The SPMD-derived analyte amounts enabled the calculation of time-weighted averages of free dissolved waterborne levels of the contaminants. Concentrations ranged from 30.0 ng·l-1 to 51.5 ng·l-1 for PAHs, 38 pg l-1 to 150 pg·l-1 for PCBs, 9.2 to 10.4 ng·l-1 for HCHs and 0.3 to 0.8 ng·l-1 for DDTs, respectively. It was also noted that the winter season generally exhibited higher contaminant concentrations for most compounds studied, which likely reflects the seasonality of their atmospheric deposition. An attempt was also made to identify possible sources of PAH contaminants in the dam by examining PAH ratios. These diagnostic ratios were inclined towards pyrogenic sources of pollution, except for the winter season where both pyrogenic and petrogenic sources likely contribute to the contamination pattern.Keywords: Hartbeespoort dam, persistent organic pollutants, semipermeable membrane devices, water-dissolved concentrations, temporal trends
Model-independent resonance parameter extraction using the trace of K and T matrices
A model-independent method for the determination of Breit-Wigner resonance
parameters is presented. The method is based on eliminating the dependence on
the choice of channel basis by analyzing the trace of the K and T matrices in
the coupled-channel formalism, rather than individual matrix elements of the
multichannel scattering matrix.Comment: 6 pages, 16 figure
Three fermions with six single particle states can be entangled in two inequivalent ways
Using a generalization of Cayley's hyperdeterminant as a new measure of
tripartite fermionic entanglement we obtain the SLOCC classification of
three-fermion systems with six single particle states. A special subclass of
such three-fermion systems is shown to have the same properties as the
well-known three-qubit ones. Our results can be presented in a unified way
using Freudenthal triple systems based on cubic Jordan algebras. For systems
with an arbitrary number of fermions and single particle states we propose the
Pl\"ucker relations as a sufficient and necessary condition of separability.Comment: 23 pages LATE
The Veldkamp space of multiple qubits
We introduce a point-line incidence geometry in which the commutation
relations of the real Pauli group of multiple qubits are fully encoded. Its
points are pairs of Pauli operators differing in sign and each line contains
three pairwise commuting operators any of which is the product of the other two
(up to sign).
We study the properties of its Veldkamp space enabling us to identify subsets
of operators which are distinguished from the geometric point of view. These
are geometric hyperplanes and pairwise intersections thereof.
Among the geometric hyperplanes one can find the set of self-dual operators
with respect to the Wootters spin-flip operation well-known from studies
concerning multiqubit entanglement measures. In the two- and three-qubit cases
a class of hyperplanes gives rise to Mermin squares and other generalized
quadrangles. In the three-qubit case the hyperplane with points corresponding
to the 27 Wootters self-dual operators is just the underlying geometry of the
E6(6) symmetric entropy formula describing black holes and strings in five
dimensions.Comment: 15 pages, 1 figure; added references, corrected typos; minor change
A comparative analysis of the impact of hygiene promotion and sanitation marketing in rural Ethiopia
Access to good quality, safe-to-use sanitation in rural Ethiopia remains low. Implementation by WASH
actors of sanitation marketing in rural Ethiopia is limited. Over four years, People In Need, in
cooperation with government partners implemented a WASH project using a “local systemstrengthening”
approach. This study compares two types of intervention to improve sanitation and
hygiene behaviours: hygiene promotion and hygiene promotion in combination with sanitation
marketing. The study found that the additional sanitation marketing component was associated with
improved latrine quality and presence of a handwashing facility near to the latrine, compared to a
hygiene promotion intervention alone. This demonstrates that sanitation marketing can add significant
value to rural WASH programs
Comparative genome mapping of the deer mouse (Peromyscus maniculatus) reveals greater similarity to rat (Rattus norvegicus) than to the lab mouse (Mus musculus)
<p>Abstract</p> <p>Background</p> <p>Deer mice (<it>Peromyscus maniculatus</it>) and congeneric species are the most common North American mammals. They represent an emerging system for the genetic analyses of the physiological and behavioral bases of habitat adaptation. Phylogenetic evidence suggests a much more ancient divergence of <it>Peromyscus </it>from laboratory mice (<it>Mus</it>) and rats (<it>Rattus</it>) than that separating latter two. Nevertheless, early karyotypic analyses of the three groups suggest <it>Peromyscus </it>to be exhibit greater similarities with <it>Rattus </it>than with <it>Mus</it>.</p> <p>Results</p> <p>Comparative linkage mapping of an estimated 35% of the deer mouse genome was done with respect to the Rattus and Mus genomes. We particularly focused on regions that span synteny breakpoint regions between the rat and mouse genomes. The linkage analysis revealed the Peromyscus genome to have a higher degree of synteny and gene order conservation with the Rattus genome.</p> <p>Conclusion</p> <p>These data suggest that: 1. the <it>Rattus </it>and <it>Peromyscus </it>genomes more closely represent ancestral Muroid and rodent genomes than that of <it>Mus</it>. 2. the high level of genome rearrangement observed in Muroid rodents is especially pronounced in <it>Mus</it>. 3. evolution of genome organization can operate independently of more commonly assayed measures of genetic change (e.g. SNP frequency).</p
Peromyscus as a Mammalian Epigenetic Model
Deer mice (Peromyscus) offer an opportunity for studying the effects of natural genetic/epigenetic variation with several advantages over other mammalian models. These advantages include the ability to study natural genetic variation and behaviors not present in other models. Moreover, their life histories in diverse habitats are well studied. Peromyscus resources include genome sequencing in progress, a nascent genetic map, and >90,000 ESTs. Here we review epigenetic studies and relevant areas of research involving Peromyscus models. These include differences in epigenetic control between species and substance effects on behavior. We also present new data on the epigenetic effects of diet on coat-color using a Peromyscus model of agouti overexpression. We suggest that in terms of tying natural genetic variants with environmental effects in producing specific epigenetic effects, Peromyscus models have a great potential
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