12,160 research outputs found
Phase diagram of the antiferromagnetic XY model in two dimensions in a magnetic field
The phase diagram of the quasi-two-dimensional easy-plane antiferromagnetic
model, with a magnetic field applied in the easy plane, is studied using the
self-consistent harmonic approximation. We found a linear dependence of the
transition temperature as a function of the field for large values of the
field. Our results are in agreement with experimental data for the spin-1
honeycomb compound BaNi_2V_2O_3Comment: 3 page
Photometric and proper motion study of neglected open cluster NGC 2215
Optical UBVRI photometric measurements using the Faulkes Telescope North were
taken in early 2011 and combined with 2MASS JHK and WISE infrared
photometry as well as UCAC4 proper motion data in order to estimate the main
parameters of the galactic open cluster NGC 2215 of which large uncertainty
exists in the current literature. Fitting a King model we estimate a core
radius of 1.120.04 (0.240.01pc) and a limiting radius of
0.5 (0.940.11pc) for the cluster. The results of isochrone
fits indicates an age of with a distance of
pc, a metallicity of dex and a reddening of
. A proportion of the work in this study was undertaken by
Australian and Canadian upper secondary school students involved in the Space
to Grow astronomy education project, and is the first scientific publication to
have utilized our star cluster photometry curriculum materials.Comment: 10 pages, 9 Figures, 3 Table
Multimodal interaction with BIM data in immersive virtual reality
In this paper, we combine the potential brought by BIM standards to AEC
processes, with the recent trends and results taken from human-computer interaction (HCI). As a result, our system supports the visualization and interaction with 3D BIM models of buildings, at full scale in an immersive virtual reality (VR) environment, using natural and multimodal HCI, namely, combining gesture with speech. We´ve carried usability and user satisfaction evaluation with a panel of architects, engineers and architect students and our research shows that such an environment allows a deeper understanding of the work throughout the design process and improve the communication between AEC specialties, during design briefs. We have concluded also, that our technology offers great
benefits during all the stages of design, from the initial phase of conceptual design until the detailed stages up to the construction work. The practical experimentation of our in-house developed system, was possible by taking advantage of the virtual reality facilities of ISCTE-IUL, namely, its PocketCAVE lab.info:eu-repo/semantics/acceptedVersio
Identification of yeasts isolated from wine-related environments and capable of producing 4-ethylphenol
www.elsevier.nl/locate/jnlabr/yfmic DOI:10.1016/S0740-0020(02)00152-1The ability to produce 4-ethylphenol from the substrate p-coumaric acid in synthetic media was evaluated for several yeast species
associated with wine production.Molar conversion rates as high as 90% were found by only Dekkera bruxellensis, D. anomala and
by some unidentified strains isolated from wine-related environments.Other unidentified strains produced traces of 4-ethylphenol.
All unidentified strains showed the same cultural characteristics as D. bruxellensis when grown on DBDM (Dekkera/Brettanomyces
differential medium) agar.The determination of long-chain fatty acid compositions and the utilization of peptide nucleic acid (PNA)
probes specific for D. bruxellensis showed that the unidentified strains did not belong to this species.Further identification, by
restriction pattern generated from PCR-amplification of the 5.8S rRNA gene and the two internal transcribed spacers (ITS),
assigned the unidentified strains to Candida cantarelli, C. wickerhamii, Debaryomyces hansenii, Kluyveromyces lactis and Pichia
guilliermondii.However, only some strains of P. guilliermondii were capable of converting p-coumaric acid into 4-ethylphenol with
efficiencies close to those observed in D. bruxellensis and D. anomala
On the Nonlinear Stability of Asymptotically Anti-de Sitter Solutions
Despite the recent evidence that anti-de Sitter spacetime is nonlinearly
unstable, we argue that many asymptotically anti-de Sitter solutions are
nonlinearly stable. This includes geons, boson stars, and black holes. As part
of our argument, we calculate the frequencies of long-lived gravitational
quasinormal modes of AdS black holes in various dimensions. We also discuss a
new class of asymptotically anti-de Sitter solutions describing noncoalescing
black hole binaries.Comment: 26 pages. 5 figure
Parasitic infections in two Benthopelagic fish from Amazon: the Arowana Osteoglossum bicirrhosum (Osteoglossidae) and Oscar Astronotus ocellatus (Cichlidae).
The parasitic fauna of wild Osteoglossum bicirrhosum from central Amazon (Brazil) and wild Astronotus ocellatus from eastern Amazon (Brazil) as well as the host-parasite relationship were evaluated. 87.5% O. bicirrhosum were parasitized only by Gonocleithrum aruanae (Monogenoidea). 92.8% A. ocellatus were parasitized by Ichthyophthirius multifiliis (Ciliophora), Gussevia asota (Monogenoidea), Posthodiplostomum sp. metacercariae (Diplostomidae), Procamallanus inopinatus adults and Contracaecum larvae (Anisakidae). High levels of infection by G. aruanae occurred in O. bicirrhosum while in A. ocellatus the highest levels of infection were caused by helminthes ectoparasites such as G. asota, and endoparasites such as Posthodiplostomum sp., P. inopinatus and Contracaecum sp. There was a significant (p>0.05) negative correlation between the intensity of helminthes species and the relative condition factor (Kn) from A. ocellatus, indicating that these parasites are pathogenic for hosts. The parasite fauna of O. bicirrhosum was scarce, while the parasites for A. ocellatus were mainly helminthes species, including adults and larval forms. Such differences on parasites fauna of both omnivore hosts may due to their history life as well as environmental and biological factors
Relação peso-comprimento e fator de condição relativo (Kn) do pirarucu Arapaima gigas Schinz, 1822 (Arapaimidae) em cultivo semi-intensivo no estado do Amazonas, Brasil.
O pirarucu Arapaima gigas (Osteoglossiformes, Arapaimidae), peixe da bacia amazônica, apresenta alta taxa de crescimento e tolerância a alta densidade de estocagem, tem rusticidade ao manuseio e aceita alimentação artificial quando treinado no inÃcio da vida, caracterÃsticas relevantes para o cultivo de peixe. Neste estudo, a relação peso-comprimento (W=a·Lb) e o fator de condição relativo (Kn) foram estimados para alevinos, juvenis e jovens de pirarucus cultivados em piscicultura semi-intensiva no municÃpio de Manacapuru, estado do Amazonas, na Amazônia central, Brasil. Alevinos foram previamente treinados para aceitar ração comercial durante no inÃcio da vida e depois foram alimentados com ração para peixes contendo 45% de proteÃna bruta. A equação relação peso-comprimento mostrou crescimento do tipo isométrico, com valor da constante de regressão (b) igual 3,068. O Kn variou de 0.811 a 1.170 (média de 1.007 ± 0.059) e esses valores elevados indicaram boas condições corporais dos peixes nas condições cultivadas
Radiocarbon and blue optically stimulated luminescence chronologies of the Oitavos consolidated dune (Western Portugal)
The dune of Oitavos, the underlying paleosol, and Helix sp. gastropod shells found within the paleosol were dated using a combination of radiocarbon and blue optically stimulated luminescence (OSL). The organic component of the paleosol produced a significantly older age (~20,000 cal BP) than the OSL age measurement (~15,000 yr), while 14C age measurements on the inorganic component and the gastropods produced ages of ~35,000 yr and ~34,000 yr, respectively. Rare-earth
element analyses provide evidence that the gastropods incorporate geological carbonate, making them an unreliable indicator of the age of the paleosol. We propose that the 14C age of the small organic component of the paleosol is also likely to be unreliable due to incorporation of residual material. The OSL age measurement of the upper paleosol (~15,000 yr) is consistent with the age for the base of the dune (~14,500 yr). The younger OSL age for the top of the dune (~12,000 yr) suggests that it was built up by at least 2 sand pulses or that there was a remobilization of material at the top during its evolution, prior to consolidation
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