Orientational dependence of the van der Waals interactions for finite-sized particles

Van der Waals forces as interactions between neutral and polarisable particles act at small distances between two objects. Their theoretical origin lies in the electromagnetic interaction between induced dipole moments caused by the vacuum fluctuations of the ground-state electromagnetic field. The resulting theory well describes the experimental situation in the limit of the point dipole assumption. At smaller distances, where the finite size of the particles has to be taken into account, this description fails and has to be corrected by higher orders of the multipole expansion, such as quadrupole moments and so on. With respect to the complexity of the spatial properties of the particles this task requires a considerable effort. In order to describe the van der Waals interaction between such particles, we apply the established method of a spatially spread out polarisability distribution to approximate the higher orders of the multipole expansion. We hence construct an effective theory for effects from anisotropy and finite size on the van der Waals potential

Effective Polarisability Models

Theories for the effective polarisability of a small particle in a medium are presented using different levels of approximation: we consider the virtual cavity, real cavity and the hard-sphere models as well as a continuous interpolation of the latter two. We present the respective hard-sphere and cavity radii as obtained from density-functional simulations as well as the resulting effective polarisabilities at discrete Matsubara frequencies. This enables us to account for macroscopic media in van der Waals interactions between molecules in water and their Casimir-Polder interaction with an interface

Influência da variabilidade meteo-oceanográfica no oceano Atlântico sudoeste sobre a pesca tubarão-azul, Prionace glauca (Linnaeus, 1758)

Brazil has approximately 8,500 km of coastline and a reasonable number of islands, totaling an area of ​​approximately 3.5 million km² of Exclusive Economic Zone (EEZ), which extends from Cape Orange (5 ºN) to the Chuí (34 ºS). Surface longline fishing is a fishing modality used worldwide in the open ocean. Currently the main ports that host the longline fleet in the Southeast region in Santos (SP) and Itaipava (ES) and in the South region the locality of Itajaí and Navegantes (SC). The blue shark, Prionace glauca (Linnaeus, 1758), is one of the species of pelagic elasmobranchs, most captured by the surface longline fleet. The blue shark is considered to be the abundant among the great pelagic sharks present in the Atlantic Ocean. It is an oceanic species, highly migratory, with global distribution, between 60 ° N and 50 ° S latitudes, occurring in tropical and temperate waters, predominantly in those with temperatures between 12 ° C - 20 ° C. The present study aims to evaluate the influence of meteo-oceanographic variability in the southwest Atlantic Ocean on the population of blue shark, Prionace glauca (Linnaeus, 1758), captured by the industrial fleet in the period 1994-2018 in the surface longline modality. For the preparation of the study, the monthly landings data for the South American Atlantic longline fleet between the years 1994 - 2018 will be analyzed.Brasil tiene aproximadamente 8,500 km de costa y un número razonable de islas, totalizando un área de aproximadamente 3.5 millones de km² de Zona Económica Exclusiva (ZEE), que se extiende desde el Cabo Naranja (5 ºN) hasta el Chuí (34 ºS). La pesca con palangre de superficie es una modalidad de pesca utilizada en todo el mundo en mar abierto. Actualmente, los principales puertos que albergan la flota de palangre en la región sureste de Santos (SP) e Itaipava (ES) y en la región sur de la localidad de Itajaí y Navegantes (SC). El tiburón azul, Prionace glauca (Linnaeus, 1758), es una de las especies de elasmobranquios pelágicos, más capturados por la flota de palangre de superficie. Se considera que el tiburón azul es el abundante entre los grandes tiburones pelágicos presentes en el Océano Atlántico. Es una especie oceánica, altamente migratoria, con una distribución global, entre latitudes de 60 ° N y 50 ° S, que ocurre en aguas tropicales y templadas, predominantemente en aquellas con temperaturas entre 12 ° C - 20 ° C. El presente estudio tiene como objetivo evaluar la influencia de la variabilidad meteo-oceanográfica en el suroeste del Océano Atlántico sobre la población del tiburón azul, Prionace glauca (Linnaeus, 1758), capturado por la flota industrial en el período 1994-2018 en la modalidad de palangre de superficie. Para la preparación del estudio, se analizarán los datos de desembarques mensuales de la flota de palangre del Atlántico sudamericano entre los años 1994-2018.O Brasil possui cerca de 8.500 km de linha de litoral e um número razoável de ilhas, totalizando uma área de aproximadamente 3,5 milhões de km² de Zona Econômica Exclusiva (ZEE), que se estendo desde o Cabo Orange (5 ºN) até o Chuí (34 ºS). A pesca com espinhel superfície é uma modalidade pesqueira mundialmente utilizada em oceano aberto. Atualmente os principais portos que abrigam a frota espinheleira na região Sudeste em Santos (SP) e Itaipava (ES) e na região Sul a localidade de Itajaí e Navegantes (SC). O tubarão-azul, Prionace glauca (Linnaeus, 1758), é uma das espécies de elasmobrânquios pelágicos, mais capturadas pela frota de espinhel de superfície. O tubarão-azul, é considerado o abundante dentre os grandes tubarões pelágicos presentes no Oceano Atlântico. É uma espécie oceânica, altamente migratória, apresenta distribuição global, entre as latitudes de 60°N e 50°S, ocorrendo em águas tropicais e temperadas, predominantemente naquelas com temperaturas entre 12°C - 20°C. A presente estudo visa avaliar a influência da variabilidade meteo-oceanográfica no oceano atlântico sudoeste sobre a população de tubarão-azul, Prionace glauca (Linnaeus, 1758), capturada pela frota industrial no período de 1994-2018 na modalidade de espinhel de superfície. Para a elaboração do estudo serão analisados ​​os dados de desembarques mensais da frota espinheleira da região do Atlântico Sudoeste entre os anos 1994 - 2018.&nbsp

The anisotropic quasi-static permittivity of single-crystal β-Ga\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e3\u3c/sub\u3e measured by terahertz spectroscopy

The quasi-static anisotropic permittivity parameters of electrically insulating beta gallium oxide (β-Ga2O3) were determined by terahertz spectroscopy. Polarization-resolved frequency domain spectroscopy in the spectral range from 200 GHz to 1 THz was carried out on bulk crystals along different orientations. Principal directions for permittivity were determined along crystallographic axes c and b and reciprocal lattice direction a*. No significant frequency dispersion in the real part of dielectric permittivity was observed in the measured spectral range. Our results are in excellent agreement with recent radio frequency capacitance measurements as well as with extrapolations from recent infrared measurements of phonon mode and high-frequency contributions and close the knowledge gap for these parameters in the terahertz spectral range. Our results are important for applications of β-Ga2O3 in high-frequency electronic devices

Influence of Radiotherapy on Ossification of Vascularized Osseous Reconstruction of the Jaw: A Radiological Retrospective Cohort Study Based on Panoramic Radiographs

Background: The aim of this study was to evaluate the impact of irradiation and time of irradiation on the ossification of jaws reconstructed with free bone grafts. Methods: In total, 100 reconstructions of the jaw were retrospectively evaluated for ossification between bone segments by two raters based on postoperative panoramic radiographs (immediate postOP, approximately 6, 12 and 24 months follow-up). Three subgroups were divided according to the time of irradiation: preoperative radiation therapy (n = 41), postoperative radiation therapy (n = 26) and patients without any radiation therapy (n = 33) as the control group. Ossification time and influencing factors were documented. Results: The fastest ossification with a median of 304 ± 37 days was observed (p < 0.001) in the nonirradiated control group. No significant difference (p = 0.087) in ossification was found between the pre- (447 ± 136 days) and postoperative (510 ± 112 days) radiation groups. Ossification between two graft segments (336 ± 38 days) showed significantly (p < 0.001) faster ossification than between the original and grafted bone (448 ± 85 days). Moreover, closer initial contact between the segments resulted in faster ossification (p < 0.001). When analyzing cofactors, tobacco consumption was the only negative factor aggravating ossification (p = 0.006). Conclusion: Head and neck radiation corresponded with the impaired and prolonged ossification of jaw reconstructions with free bone grafts. There was no difference in ossification if radiotherapy was performed before or after reconstructive surgery. A close bony contact was particularly important for ossification between the original and grafted bone