11,291 research outputs found
Entanglement of two qubits mediated by one-dimensional plasmonic waveguides
We investigate qubit-qubit entanglement mediated by plasmons supported by
one-dimensional waveguides. We explore both the situation of spontaneous
formation of entanglement from an unentangled state and the emergence of driven
steady-state entanglement under continuous pumping. In both cases, we show that
large values for the concurrence are attainable for qubit-qubit distances
larger than the operating wavelength by using plasmonic waveguides that are
currently available.Comment: 4 pages, 4 figures. Minor Changes. Journal Reference added.
Highlighted in Physic
Selection properties of the baited hooks used in the Cuban longline fishery of Campeche Bank, Gulf of Mexico
A description of the Cuban set longline fishery on Campeche Bank, Gulf of Mexico is given, with emphasis on the effects of different species of pelagic fishes used as bait. The target species is the red grouper Epinephelus morio, with incidental species consisting of other epinephelids (13%), lutjanids (5.4%) and sparids (1.6%)
Effect of dietary sunflower hulls on nutrient digestibility, ileal morphology, and volatile fatty acid concentration in broilers and pullets fed a broiler diet from 1 to 21 days of age
The effects of sunflower hulls (SFH) inclusion on performance, TTAR of nutrients, ileal mucosa morphology, and volatile fatty acid (VFA) concentration in the ceca were studied in birds from 1 to 21 d of age. There were 4 treatments organized as 2 Ă— 2 factorial with 2 chicken lines (broilers vs. pullets) and 2 levels of SFH (0 vs. 3%). Each treatment was replicated 7 times (10 birds). The corn-soybean meal control diet contained 3,010 kcal AMEn/kg, 1.25% digestible Lys, and 8.7% NDF. In the experimental diet, SFH was included at the expense (wt:wt) of the control diet. Diets were offered in mash form. No interactions between main effects were detected for any trait. From 1 to 21 d of age, ADG was greater and FCR was better in broilers than in pullets (P < 0.001) but SFH inclusion did not affect bird performance. The TTAR of all nutrients was higher (P < 0.05) in broilers than in pullets. The inclusion of SFH improved AMEn of the diet (P < 0.05) at both ages and DM and N retention (P < 0.001) at 21 d. Broilers had larger villus and deeper crypt (P < 0.01) than pullets. Broilers tended to have higher (P = 0.077) cecal proportion of acetate than pullets but no effects were observed for the other VFA. SFH inclusion tended to increased villus height (P < 0.05) and cecal proportion of acetate and propionate (P < 0.01). In summary, broilers grew faster, were more efficient, had higher ileum absorptive capacity, TTAR of nutrients than pullets. The inclusion of 3% SFH in substitution (wt:wt) of the whole diet improved AMEn without showing any negative effect on growth performance of the bird
Presencia de Aphis arbuti Ferrari y Wahlgreniella nervata (Gillete) (Hemiptera, Aphididae) en los madroños de la Comunidad de Madrid y estudio de la fumagina asociada.
Determinación de los pulgones asociados al madroño y su relación con los hongos desarrollados sobre la melaza
Fragility of spectral flow for topological phases in non-Wigner-Dyson classes
Topological insulators and superconductors support extended surface states
protected against the otherwise localizing effects of static disorder.
Specifically, in the Wigner-Dyson insulators belonging to the symmetry classes
A, AI, and AII, a band of extended surface states is continuously connected to
a likewise extended set of bulk states forming a ``bridge'' between different
surfaces via the mechanism of spectral flow. In this work we show that this
principle becomes \emph{fragile} in the majority of non-Wigner-Dyson
topological superconductors and chiral topological insulators. In these
systems, there is precisely one point with granted extended states, the center
of the band, . Away from it, states are spatially localized, or can be
made so by the addition of spatially local potentials. Considering the
three-dimensional insulator in class AIII and winding number as a
paradigmatic case study, we discuss the physical principles behind this
phenomenon, and its methodological and applied consequences. In particular, we
show that low-energy Dirac approximations in the description of surface states
can be treacherous in that they tend to conceal the localizability phenomenon.
We also identify markers defined in terms of Berry curvature as measures for
the degree of state localization in lattice models, and back our analytical
predictions by extensive numerical simulations. A main conclusion of this work
is that the surface phenomenology of non-Wigner-Dyson topological insulators is
a lot richer than that of their Wigner-Dyson siblings, extreme limits being
spectrum wide quantum critical delocalization of all states vs. full
localization except at the critical point. As part of our study we
identify possible experimental signatures distinguishing between these
different alternatives in transport or tunnel spectroscopy.Comment: 16 pages, 8 figure
Review: Towards the agroecological management of ruminants, pigs and poultry through the development of sustainable breeding programmes. II. Breeding strategies
Agroecology uses ecological processes and local resources rather than chemical inputs to develop productive and resilient livestock and crop production systems. In this context, breeding innovations are necessary to obtain animals that are both productive and adapted to a broad range of local contexts and diversity of systems. Breeding strategies to promote agroecological systems are similar for different animal species. However, current practices differ regarding the breeding of ruminants, pigs and poultry. Ruminant breeding is still an open system where farmers continue to choose their own breeds and strategies. Conversely, pig and poultry breeding is more or less the exclusive domain of international breeding companies which supply farmers with hybrid animals. Innovations in breeding strategies must therefore be adapted to the different species. In developed countries, reorienting current breeding programmes seems to be more effective than developing programmes dedicated to agroecological systems that will struggle to be really effective because of the small size of the populations currently concerned by such systems. Particular attention needs to be paid to determining the respective usefulness of cross-breeding v. straight breeding strategies of well-adapted local breeds. While cross-breeding may offer some immediate benefits in terms of improving certain traits that enable the animals to adapt well to local environmental conditions, it may be difficult to sustain these benefits in the longer term and could also induce an important loss of genetic diversity if the initial pure-bred populations are no longer produced. As well as supporting the value of within-breed diversity, we must preserve between-breed diversity in order to maintain numerous options for adaptation to a variety of production environments and contexts. This may involve specific public policies to maintain and characterize local breeds (in terms of both phenotypes and genotypes), which could be used more effectively if they benefited from the scientific and technical resources currently available for more common breeds. Last but not least, public policies need to enable improved information concerning the genetic resources and breeding tools available for the agroecological management of livestock production systems, and facilitate its assimilation by farmers and farm technicians
Bogomolny equations for vortices in the noncommutative torus
We derive Bogomolny-type equations for the Abelian Higgs model defined on the
noncommutative torus and discuss its vortex like solutions. To this end, we
carefully analyze how periodic boundary conditions have to be handled in
noncommutative space and discussed how vortex solutions are constructed. We
also consider the extension to an model, a simplified
prototype of the noncommutative standard model.Comment: 23 pages, no figure
LZS/Al2O3 nanostructured composites obtained by colloidal processing and spark plasma sintering
[EN] Li2O-SiO2-ZrO2 (LZS) glass-ceramics have high mechanical strength, hardness, resistance to abrasion and chemical attack, but also a high coefficient of thermal expansion (CTE), which can be reduced adding alumina nanoparticles. The conventional glass-ceramic production is relatively complex and energy consuming, since it requires the melting of the raw materials to form a glass frit and a two-step milling process to obtain particle sizes adequate for compaction. This study describes the preparation of LZS glass-ceramics through a colloidal processing approach from mixtures of SiO2 and ZrO2 nanopowders and a Li precursor (lithium acetate obtained by reaction of the carbonate with acetic acid). Concentrated suspensions were freeze-dried to obtain homogeneous mixtures of powders that were pressed (100 MPa) and sintered conventionally and by spark plasma sintering. The effect of the alumina nanoparticles additions on suspensions rheology, sintering behavior and properties such as thermal expansion, thermal conductivity, hardness and Young's modulus were evaluated. (C) 2017 Elsevier Ltd. All rights reserved.This work has been supported by Ministerio de Economia y Competitividad (MINECO) and FEDER Funds under grant No MAT2016-67586-C3-R. Authors greatly acknowledge the financial Support of CAPES in the frame of the International Cooperation Program Science without Borders for Special Visiting Researcher PVE (MEC/MCTI/CAPES/CNPQ/FAPs/No 71/2013), Project no. A011/2013. A. Borrell acknowledges the MINECO for her Juan de la Cierva-Incorporacion contract (IJCI-2014-19839).Arcaro, S.; Novaes De Oliveira, A.; Gutierrez-Gonzalez, C.; Salvador Moya, MD.; Borrell Tomás, MA.; Moreno, R. (2017). LZS/Al2O3 nanostructured composites obtained by colloidal processing and spark plasma sintering. Journal of the European Ceramic Society. 37(16):5139-5148. https://doi.org/10.1016/j.jeurceramsoc.2017.03.023S51395148371
Providing Personalized Guidance in Arithmetic Problem Solving
Supervising a student's resolution of an arithmetic word problem is a cumbersome task. Di erent students may use di erent lines of reasoning to reach the nal solution, and the assistance provided should be consistent with the resolution path that the student has in mind. In addition, further learning gains can be achieved if the previous student's background is also considered in the process. In this paper, we outline a relatively simple method to adapt the hints given by an Intelligent Tutoring System to the line of reasoning that the student is currently following. We also outline possible extensions to build a model of the student's most relevant skills, by tracking user's actions
The Neotropical species of Clistopyga (Hymenoptera, Ichneumonidae, Pimplinae). Part I: the C. chaconi species group, with the description of eleven new species
The New World Clistopyga chaconi species group is revised. Eleven species are described as new: C. amazonica sp. nov., C. cinnamoptera sp. nov., C. cuscoensis sp. nov., C. hayesiana sp. nov., C. melanoptera sp. nov., C. misionensis sp. nov., C. mocaguae sp. nov., C. orellanae sp. nov., C. porteri sp. nov., C. rondoniae sp. nov. and C. yabuquensis sp. nov. Additional morphological data are provided for the previously known species, C. caramba Castillo & Saaksjarvi and C. chaconi Gauld. An illustrated identification key to all species of the group is provided. The Clistopyga chaconi species group appears to be most diverse at the Andean and Amazonian interface in western South America
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