A retrospective study of zygomatico-orbital complex and/or zygomatic arch fractures over a 71-month period

Background/Aim: The aim of this retrospective study was to evaluate the epidemiology, treatment, and complications of zygomatico-orbital complex (ZOC) and/or zygomatic arch (ZA) fractures either associated with other facial fractures or not over a 71-month period. Material and methods: This survey was performed in three hospitals of Ribeirao Preto in Sao Paulo, Brazil, from August 2002 to July 2008. The records of 1575 patients with facial trauma were reviewed. There were 140 cases of ZOC and ZA fractures either associated with other facial fractures or not. Data regarding gender, age, race, addictions, day of trauma, etiology, signs and symptoms, oral hygiene condition, day of initial evaluation, hospital admission, day of surgery, surgery approach, pattern of fractures, treatment performed, post-operative antibiotic therapy, day of hospital discharge, and post-operative complications were collected. The data were subjected to descriptive statistical analyses. Results: The most frequent fractures affected Caucasian men and occurred during the fourth decade of life. The most frequent etiology was traffic accident, and symptoms and signs included pain and edema. Type I fractures were the main injury observed, and the treatment of choice was always rigid internal fixation. Post-operative antibiotic therapy was solely employed when there was an indication. Complications were observed in 13.1% of the cases. Conclusions: The treatment protocol yielded suitable post-operative results and also showed success rates comparable to published data around the world.

Reliability of orbital fits for resonant extrasolar planetary systems: the case of HD82943

We perform a statistical study of the process of orbital determination of the HD82943 extrasolar planetary system, using the current observational data set of N = 165 radial velocity (RV) measurements. Our aim is to analyse the dispersion of possible orbital fits leading to residuals compatible with the best solution, and to discuss the sensitivity of the results with respect to both the data set and the error distribution around the best fit. Although some orbital parameters (e.g. semimajor axis) appear well constrained, we show that the best fits for the HD82943 system are not robust, and at present it is not possible to estimate reliable solutions for these bodies. Finally, we discuss the possibility of a third planet, with a mass of 0.35M(Jup) and an orbital period of 900 d. Stability analysis and simulations of planetary migration indicate that such a hypothetical three-planet system could be locked in a double 2/1 mean-motion resonance, similar to the so-called Laplace resonance of the three inner Galilean satellites of Jupiter.

Dynamics of two planets in co-orbital motion

We study the stability regions and families of periodic orbits of two planets locked in a co-orbital configuration. We consider different ratios of planetary masses and orbital eccentricities; we also assume that both planets share the same orbital plane. Initially, we perform numerical simulations over a grid of osculating initial conditions to map the regions of stable/chaotic motion and identify equilibrium solutions. These results are later analysed in more detail using a semi-analytical model. Apart from the well-known quasi-satellite orbits and the classical equilibrium Lagrangian points L(4) and L(5), we also find a new regime of asymmetric periodic solutions. For low eccentricities these are located at (delta lambda, delta pi) = (+/- 60 degrees, -/+ 120 degrees), where delta lambda is the difference in mean longitudes and delta pi is the difference in longitudes of pericentre. The position of these anti-Lagrangian solutions changes with the mass ratio and the orbital eccentricities and are found for eccentricities as high as similar to 0.7. Finally, we also applied a slow mass variation to one of the planets and analysed its effect on an initially asymmetric periodic orbit. We found that the resonant solution is preserved as long as the mass variation is adiabatic, with practically no change in the equilibrium values of the angles.

Constraining the orbital orientation of eta Carinae from H Paschen lines

During the past decade, several observational and theoretical works have provided evidence of the binary nature of eta Carinae. Nevertheless, there is still no direct determination of the orbital parameters, and the different current models give contradictory results. The orbit is, in general, assumed to coincide with the Homunculus equator although the observations are not conclusive. Among all systems, eta Car has the advantage that it is possible to observe both the direct emission of line transitions in the central source and its reflection by the Homunculus, which is dependent on the orbital inclination. In this work, we studied the orbital phase-dependent hydrogen Paschen spectra reflected by the south-east lobe of the Homunculus to constrain the orbital parameters of eta Car and determine its inclination with respect to the Homunculus axis. Assuming that the emission excess originates in the wind-wind shock region, we were able to model the latitude dependence of the spectral line profiles. For the first time, we were able to estimate the orbital inclination of eta Car with respect to the observer and to the Homunculus axis. The best fit occurs for an orbital inclination to the line of sight of i similar to 60 degrees +/- 10 degrees, and i* similar to 35 degrees +/- 10 degrees with respect to the Homunculus axis, indicating that the angular momenta of the central object and the orbit are not aligned. We were also able to fix the phase angle of conjunction as similar to -40 degrees, showing that periastron passage occurs shortly after conjunction.

DETECTABILITY AND ERROR ESTIMATION IN ORBITAL FITS OF RESONANT EXTRASOLAR PLANETS

We estimate the conditions for detectability of two planets in a 2/1 mean-motion resonance from radial velocity data, as a function of their masses, number of observations and the signal-to-noise ratio. Even for a data set of the order of 100 observations and standard deviations of the order of a few meters per second, we find that Jovian-size resonant planets are difficult to detect if the masses of the planets differ by a factor larger than similar to 4. This is consistent with the present population of real exosystems in the 2/1 commensurability, most of which have resonant pairs with similar minimum masses, and could indicate that many other resonant systems exist, but are currently beyond the detectability limit. Furthermore, we analyze the error distribution in masses and orbital elements of orbital fits from synthetic data sets for resonant planets in the 2/1 commensurability. For various mass ratios and number of data points we find that the eccentricity of the outer planet is systematically overestimated, although the inner planet`s eccentricity suffers a much smaller effect. If the initial conditions correspond to small-amplitude oscillations around stable apsidal corotation resonances, the amplitudes estimated from the orbital fits are biased toward larger amplitudes, in accordance to results found in real resonant extrasolar systems.

Synthesis, mechanism of formation, and molecular orbital calculations of arylamidoximes

A simple and easy synthesis of ten arylamidoximes from arylnitriles and hydroxylamine is described. The formation of the arylamides has been observed to a much lesser extent in the present work. A new mechanism for the formation of arylamidoximes, as well as arylamides, from arylnitriles and hydroxylamine is suggested. Quantum mechanical calculations have been carried out to support this mechanism. The enthalpy of formation in conjunction with atomic charges of the reactants and intermediates helped to understand more about the generation of the products.

Structural, electronic, and magnetic entropy contributions of the orbital order-disorder transition in LaMnO(3)

Measurements of X-ray diffraction, electrical resistivity, and magnetization are reported across the Jahn-Teller phase transition in LaMnO(3). Using a thermodynamic equation, we obtained the pressure derivative of the critical temperature (T(JT)), dT(JT)/dP = -28.3 K GPa(-1). This approach also reveals that 5.7(3)J(mol K)(-1) comes from the volume change and 0.8(2)J(mol K)(-1) from the magnetic exchange interaction change across the phase transition. Around T(JT), a robust increase in the electrical conductivity takes place and the electronic entropy change, which is assumed to be negligible for the majority of electronic systems, was found to be 1.8(3)J(mol K)(-1).

Dependence of Response Functions and Orbital Functionals on Occupation Numbers

Explicitly orbital-dependent approximations to the exchange-correlation energy functional of density functional theory typically not only depend on the single-particle Kohn-Sham orbitals but also on their occupation numbers in the ground-state Slater determinant. The variational calculation of the corresponding exchange-correlation potentials with the optimized effective potential (OEP) method therefore also requires a variation of the occupation numbers with respect to a variation in the effective single-particle potential, which is usually not taken into account. Here it is shown under which circumstances this procedure is justified.

Orbital-polarization terms: From a phenomenological to a first-principles description of orbital magnetism in density-functional theory

Phenomenological orbital-polarizition (OP) terms have been repeatedly introduced in the single-particle equations of spin-density-functional theory, in order to improve the description of orbital magnetic moments in systems containing transition metal ions. Here we show that these ad hoc corrections can be interpreted as approximations to the exchange-correlation vector potential A(xc) of current-density functional theory (CDFT). This connection provides additional information on both approaches: phenomenological OP terms are connected to first-principles theory, leading to a rationale for their empirical success and a reassessment of their limitations and the approximations made in their derivation. Conversely, the connection of OP terms with CDFT leads to a set of simple approximations to the CDFT potential A(xc), with a number of desirable features that are absent from electron-gas-based functionals. (C) 2008 Wiley Periodicals, Inc.

New Relativistic Atomic Natural Orbital Basis Sets for Lanthanide Atoms with Applications to the Ce Diatom and LuF3

New basis sets of the atomic natural orbital (ANO) type have been developed for the lanthanide atoms La-Lu. The ANOs have been obtained from the average density matrix of the ground and lowest excited states of the atom, the positive ions, and the atom in an electric field. Scalar relativistic effects are included through the use of a Douglas-Kroll-Hess Hamiltonian. Multiconfigurational wave functions have been used with dynamic correlation included using second-order perturbation theory (CASSCF/CASPT2). The basis sets are applied in calculations of ionization energies and some excitation energies. Computed ionization energies have an accuracy better than 0.1 eV in most cases. Two molecular applications are inluded as illustration: the cerium diatom and the LuF3 molecule. In both cases it is shown that 4f orbitals are not involved in the chemical bond in contrast to an earlier claim for the latter molecule.

Crystal and molecular structures of three 2-sulphur-substituted cyclohexanones studied by X-ray crystallography and by ab initio molecular orbital calculations

The conformational features of three 2-sulphur-substituted cyclohexanone derivatives, which differ in the number of sulphur-bound oxygen atoms, i.e. zero (I), one (II) and two (III), were investigated by single crystal X-ray crystallography and geometry optimized structures determined using Hartree-Fock method. In each of (I)-(III) an intramolecular S center dot center dot center dot O(carbonyl) interaction is found with the magnitude correlated with the oxidation state of the sulphur atom, i.e. 2.838(3) angstrom in (I) to 2.924(2) angstrom in (II) to 3.0973(18) angstrom in (III). There is an inverse relationship between the strength of this interaction and the magnitude of the carbonyl bond. The supramolecular aggregation patterns are primarily determined by C-H center dot center dot center dot O contacts and are similarly influenced by the number of oxygen atoms in the molecular structures. Thus, a supramolecular chain is found in the crystal structure of (I). With an additional oxygen atom available to participate in C-H center dot center dot center dot O interactions, as in (II), a two-dimensional array is found. Finally, a three-dimensional network is found for (III). Despite there being differences in conformations between the experimental structures and those calculated in the gas-phase, the S center dot center dot center dot O interactions persist. The presence of intermolecular C-H center dot center dot center dot O interactions involving the cyclohexanone-carbonyl group in the solid-state, disrupts the stabilising intramolecular C-H center dot center dot center dot O interaction in the energetically-favoured conformation. (I): C(12)H(13)NO(3)S, triclinic space group P (1) over bar with a = 5.392(3) angstrom b = 10.731(6) angstrom, c = 11.075(6) angstrom, alpha = 113.424(4)degrees, beta = 94.167(9)degrees, gamma = 98.444(6)degrees, V = 575.5(6) angstrom(3), Z = 2, R(1) = 0.052; (II): C(12)H(13)NO(4)S, monoclinic P2(1)/n, a = 7.3506(15) angstrom, b = 6.7814(14) angstrom, c = 23.479(5) angstrom, beta = 92.94(3)degrees, V = 1168.8(4) angstrom(3), Z = 4, R(1) = 0.046; (III): C(12)H(13)NO(5)S, monoclinic P2(1)/c, a = 5.5491(11) angstrom, b = 24.146(3) angstrom, c = 11.124(3) angstrom, beta = 114.590(10)degrees, V = 1355.3(5) angstrom(3), Z = 4, R(1) = 0.051.

Aplicação de sensoriamento remoto orbital no mapeamento de unidades vulcano-sedimentar no Platô da Ramada, Vila Nova do Sul, RS

Os produtos de sensoriamento remoto gerados pelos novos sensores orbitais, aliados ao desenvolvimento de sistemas computacionais e de técnicas de processamento de imagens possibilitam a manipulação numérica das imagens, visando o realce de informações de interesse para a interpretação visual ou automática. O uso dessas técnicas traz boas perspectivas no mapeamento geológico básico, pois possibilita uma visão sinóptica de amplas áreas e a integração de dados litológicos e estruturais de várias fontes. Este trabalho selecionou as imagens do sensor ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) devido as características de suas resoluções espectral e espacial, como as mais promissoras para identificação dos diferentes litotipos da área do Platô da Ramada, em especial as unidades vulcânicas e hipabissais relacionadas e sedimentares subjacentes. O Platô da Ramada, região de Vila Nova do Sul (RS) constitui uma feição geomorfológica de destaque na área, facilmente identificável nas imagens orbitais, sendo formado por uma seqüência vulcânica caracterizada por depósitos efusivos e piroclásticos, de composição dominantemente ácida. Representa uma fração significativa do magmatismo alcalino sódico neoproterozóico no Escudo Sul-rio-grandense e marca um dos ciclos vulcânicos do período pós-colisional do Ciclo Brasiliano Este estudo testou e avaliou diversos processamentos das imagens multiespectrais para diferenciação litológica, a identificação de alvos e a definição de morfoestruturas da área do Platô da Ramada. A integração de dados geológicos existentes com os produtos obtidos neste estudo possibilitou novas informações anexadas ao mapa geológico utilizado como verdade terrestre. O processamento utilizando a técnica de Transformação por Componentes Principais Seletivas proporcionou os melhores resultados realçando diferenças espectrais existentes entre as rochas vulcânicas e hipabissais e as rochas sedimentares. A partir dessa técnica, selecionou-se as imagens CP2 dos pares das bandas 4-5 (R), 3-4 (G) e 8-9 (B) na geração de uma composição colorida. Esta imagem permitiu a diferenciação espectral entre as rochas vulcânicas do Platô da Ramada e as rochas sedimentares do Grupo Maricá, bem como a individualização, no Grupo Maricá, de duas subunidades, levando-se em conta a densidade de intrusões de diques riolíticos ao norte da área. Identificou-se, ainda, um corpo diorítico com forma elíptica na borda SW do Platô da Ramada, não registrado anteriormente.

Monitoramento de temperaturas noturnas da superfície terrestre no estado do Rio Grande do Sul com uso do sensor orbital AVHRR/NOAA

A temperatura da superfície terrestre (TST), além da ação determinante sobre o crescimento e o desenvolvimento das plantas, influencia também muitos processos físicos, químicos e biológicos, tendo significativa relevância científica em um vasto campo das atividades de pesquisa e gerenciamento dos recursos naturais. O objetivo geral deste estudo foi verificar a adequação do uso de sensores orbitais AVHRR/3 NOAA (National Oceanic and Atmospheric Administration) classe POES (Polar Operational Environmental Satellites) para mapeamento de temperaturas da superfície terrestre no Rio Grande do Sul, visando sua implementação em programas operacionais de monitoramento agrometeorológico. No estudo realizado no período de junho a setembro de 2002, foram utilizadas 11 imagens noturnas e 20 imagens diurnas, captadas na estação de recepção de imagens NOAA pertencente ao Centro Estadual de Pesquisas em Sensoriamento Remoto e Meteorologia (CEPSRM). Após processamento, as imagens foram utilizadas para a determinação da temperatura de brilho da banda 4 e 5 da TST através dos métodos de Becker e Li (1990), Kerr et al. (1992) e Sobrino et al. (1993). A TST obtida a partir das imagens foi comparada aos dados de temperatura do ar obtidos em 13 estações meteorológicas de superfície Os resultados mostraram que os sensores orbitais AVHRR/3 são adequados para o mapeamento noturno de temperaturas da superfície terrestre no Rio Grande do Sul. O método de Sobrino et al. (1993) é o mais adequado entre os métodos testados para a estimativa das temperaturas noturnas no Estado, embora ainda seja necessário um aprofundamento teórico em relação aos efeitos atmosféricos sobre regiões localizadas em baixas latitudes. Também a temperatura estimada por sensores remotos pode ser utilizada para estimar a temperatura do ar nos locais avaliados, sendo que ainda deve ser testada a extrapolação para outros locais.

Teoria do Orbital Molecular (TOM)

O material aborda a Teoria do Orbital Molecular (TOM), ressaltando o conceito de energia e probabilidade. O objetivo é propiciar a compreensão da teoria através da visualização das ligações dos orbitais.