642 research outputs found
POTENCIALIDADES EDUCATIVAS DE ASPECTOS GEOMORFOLÓGICOS DA SERRA DOS TAPUIAS – BAHIA.
O presente artigo discute a potencialidade didática de dois sítios geomorfológicos da Serra dos Tapuias, município de Riachão das Neves, Bahia. Para sua realização foram realizadas busca de referencial teórico, reconhecimento em campo para compartimentação da paisagem e técnicas de inventariação e avaliação de patrimônio geológico segundo seu caráter educativo. Após análise percebe-se que as áreas configuram-se com potencial para a instituição de práticas ligadas a educação ambiental
Molecular regimes in ultracold Fermi gases
The use of Feshbach resonances for tuning the interparticle interaction in
ultracold Fermi gases has led to remarkable developments, in particular to the
creation and Bose-Einstein condensation of weakly bound diatomic molecules of
fermionic atoms. These are the largest diatomic molecules obtained so far, with
a size of the order of thousands of angstroms. They represent novel composite
bosons, which exhibit features of Fermi statistics at short intermolecular
distances. Being highly excited, these molecules are remarkably stable with
respect to collisional relaxation, which is a consequence of the Pauli
exclusion principle for identical fermionic atoms. The purpose of this review
is to introduce theoretical approaches and describe the physics of molecular
regimes in two-component Fermi gases and Fermi-Fermi mixtures, focusing
attention on quantum statistical effects.Comment: Chapter of the book: "Cold Molecules: Theory, Experiment,
Applications" edited by R. V. Krems, B. Friedrich and W. C. Stwalley
(publication expected in March 2009
Delayed Fluorescence by Triplet–Triplet Annihilation from Columnar Liquid Crystal Films
Delayed fluorescence (DF) by triplet–triplet annihilation (TTA) is observed in solutions of a benzoperylene-imidoester mesogen that shows a hexagonal columnar mesophase at room temperature in the neat state. A similar benzoperylene-imide with a slightly smaller HOMO–LUMO gap, that also is hexagonal columnar liquid crystalline at room temperature, does not show DF in solution, and mixtures of the two mesogens show no DF in solution either, because of collisional quenching of the excited triplet states on the imidoester by the imide. In contrast, DF by TTA from the imide but not from the imidoester is observed in condensed films of such mixtures, even though neat films of either single material are not displaying DF. In contrast to the DF from the monomeric imidoester in solution, DF of the imide occurs from dimeric aggregates in the blend films, assisted by the imidoester. Thus, the close contact of intimately stacked molecules of the two different species in the columnar mesophase leads to a unique mesophase-assisted aggregate DF. This constitutes the first observation of DF by TTA from the columnar liquid crystalline state. If the imide is dispersed in films of polybromostyrene, which provides an external heavy-atom effect facilitating triplet formation, DF is also observed. Organic light-emitting diodes (OLEDs) devices incorporating these liquid crystal molecules demonstrated high external quantum efficiency (EQE). On the basis of the literature and to the best of our knowledge, the EQE reported is the highest among nondoped solution-processed OLED devices using a columnar liquid crystal molecule as the emitting layer
Partially filled stripes in the two dimensional Hubbard model: statics and dynamics
The internal structure of stripes in the two dimensional Hubbard model is
studied by going beyond the Hartree-Fock approximation. Partially filled
stripes, consistent with experimental observations, are stabilized by quantum
fluctuations, included through the Configuration Interaction method. Hopping of
short regions of the stripes in the transverse direction is comparable to the
bare hopping element. The integrated value of compares well
with experimental results.Comment: 4 page
Intercomparison Study of Six HTDMAs: Results and Recommendations
We report on an intercomparison of six different hygroscopicity tandem differential mobility analysers (HTDMAs). These HTDMAs are used worldwide in laboratory experiments and field campaigns to measure the water uptake of aerosol particles and have never been intercompared. After an investigation of the different design of the instruments with their advantages and inconveniencies, the methods for calibration, validation and data analysis are presented. Measurements of nebulised ammonium sulphate as well as of secondary organic aerosol generated from a smog chamber were performed. Agreement and discrepancies between the instruments and to the theory are discussed, and final recommendations for a standard instrument are given, as a benchmark for laboratory or field experiments to ensure a high quality of HTDMA data.JRC.H.2-Climate chang
Search for a Higgs Boson Decaying to Weak Boson Pairs at LEP
A Higgs particle produced in association with a Z boson and decaying into
weak boson pairs is searched for in 336.4 1/pb of data collected by the L3
experiment at LEP at centre-of-mass energies from 200 to 209 GeV. Limits on the
branching fraction of the Higgs boson decay into two weak bosons as a function
of the Higgs mass are derived. These results are combined with the L3 search
for a Higgs boson decaying to photon pairs. A Higgs produced with a Standard
Model e+e- --> Zh cross section and decaying only into electroweak boson pairs
is excluded at 95% CL for a mass below 107 GeV
An Integrated TCGA Pan-Cancer Clinical Data Resource to Drive High-Quality Survival Outcome Analytics
For a decade, The Cancer Genome Atlas (TCGA) program collected clinicopathologic annotation data along with multi-platform molecular profiles of more than 11,000 human tumors across 33 different cancer types. TCGA clinical data contain key features representing the democratized nature of the data collection process. To ensure proper use of this large clinical dataset associated with genomic features, we developed a standardized dataset named the TCGA Pan-Cancer Clinical Data Resource (TCGA-CDR), which includes four major clinical outcome endpoints. In addition to detailing major challenges and statistical limitations encountered during the effort of integrating the acquired clinical data, we present a summary that includes endpoint usage recommendations for each cancer type. These TCGA-CDR findings appear to be consistent with cancer genomics studies independent of the TCGA effort and provide opportunities for investigating cancer biology using clinical correlates at an unprecedented scale. Analysis of clinicopathologic annotations for over 11,000 cancer patients in the TCGA program leads to the generation of TCGA Clinical Data Resource, which provides recommendations of clinical outcome endpoint usage for 33 cancer types
Expert considerations and consensus for using dogs to detect human SARS-CoV-2-infections
Funding Information: This Open Access publication was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – 491094227 “Open Access Publication Funding” and the University of Veterinary Medicine Hannover, Foundation.Peer reviewe
- …