Systematics of species of the genus Akodon (Rodentia: Sigmodontinae) in southeastern Brazil and implications for the biogeography of the Campos de Altitude

http://deepblue.lib.umich.edu/bitstream/2027.42/111041/1/MP197.pd

Systematics of species of the genus Akodon (Rodentia: Sigmodontinae) in southeastern Brazil and implications for the biogeography of the Campos de Altitude.

Faunal inventories of the highest peaks of the Atlantic forests of South America, in the Caparaó and Itatiaia mountain ranges in Southeastern Brazil, have revealed a new community of small mammals. The species making up this community appear to be restricted to the highest altitudinal zones and are found in close association with scattered montane grasslands (campos de altitude). Their phylogenetic relationships can provide insights into speciation in mountaintop communities of the Atlantic forest. In this paper we review the taxonomic identity and systematic relationships of Akodon mystax, a high- altitude endemic described from Caparaó. We demonstrate that populations from Itatiaia previously assigned to mystax are morphologically, cytogenetically and genetically distinct from that species and appear to represent a northern isolate of Akodon paranaensis, and that Akodon mystax is closely related to Akodon lindberghi from the Central Brazilian grasslands. Phylogenetic relationships among these populations demonstrate that differentiation of the mountaintop endemics of Caparaó and Itatiaia is not solely attributable the isolation of campos de altitude from southern grasslands of Brazil and Uruguay as grasslands retreated southward, phylogenetic analyses of some groups suggest connections between the campos de altitude and Central Brazil."http://deepblue.lib.umich.edu/bitstream/2027.42/102734/1/MP197.pd

Galerkin Method in the Gravitational Collapse: a Dynamical System Approach

We study the general dynamics of the spherically symmetric gravitational collapse of a massless scalar field. We apply the Galerkin projection method to transform a system of partial differential equations into a set of ordinary differential equations for modal coefficients, after a convenient truncation procedure, largely applied to problems of turbulence. In the present case, we have generated a finite dynamical system that reproduces the essential features of the dynamics of the gravitational collapse, even for a lower order of truncation. Each initial condition in the space of modal coefficients corresponds to a well definite spatial distribution of scalar field. Numerical experiments with the dynamical system show that depending on the strength of the scalar field packet, the formation of black-holes or the dispersion of the scalar field leaving behind flat spacetime are the two main outcomes. We also found numerical evidence that between both asymptotic states, there is a critical solution represented by a limit cycle in the modal space with period $\Delta u \approx 3.55$.Comment: 9 pages, revtex4, 10 ps figures; Phys. Rev. D, in pres

Emissary Foramens Of The Human Skull: Anatomical Characteristics And Its Relations With Clinical Neurosurgery [forámenes Emisarios Del Cráneo Humano: Características Anatómicas Y Sus Relaciones Con La Neurocirugía Clínica]

The recognition of emissary foramens is important not only for understanding the regional neurovascular anatomy, but also to distinguish normal from potentially abnormal structures. Thus, the aim of this study was to review the literature on anatomical and clinical aspects of the mastoid, parietal and sphenoid emissary foramens. It was found that the emissary foramen presents importance in clinical practice because it acts as a route of spread of extracranial infection to the intracranial structures and also possible complications in neurosurgery, due to its influence in the performance of techniques such as radiofrequency rhizotomy for treatment of trigeminal neuralgia. The anatomical knowledge of the emissary foramens is important due to variability in their incidence in the human skull and its relation to the dura mater sinuses.311287292Bergman, R.A., Afifi, A.K., Miyauchi, R., (1995) Illustrated Encyclopedia of Human Anatomic Variation: Opus V: Skeletal systems: CraniumBoyd, G.I., Emissary foramina of cranium in man and the anthropoids (1930) J. Anat., 65, pp. 108-121Casella, A.M.B., Monteiro, M.L.R., Rgensteiner, D.B.W., Caldeira, J.B.F., Regeneração aberrante do nervo do oculomotor após tromboflebite do seio cavernoso (1998) Arq. Bras. Oftalmol., 51, pp. 135-137Currarino, G., Normal variants and congenital anomalies in the region of the obelion (1976) Am. J. Roentgenol., 127 (3), pp. 487-494El Kettani, C., Badaoui, R., Fikri, M., Jeanjean, P., Montpellier, D., Tchaoussov, J., Pulmonary edema after venous air embolism during craniotomy (2002) Eur. J. 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Neuropsiq., 61 (2), pp. 434-440Kaalin, R.J., Robinson, W.A., Septic cavernous sinus thrombosis (1984) Ann. Emerg. Med., 13, pp. 449-455Kaplan, M., Erol, F.S., Ozveren, M.F., Topsakal, C., Sam, B., Tekdemir, I., Review of complications due to foramen ovale puncture (2007) J. Clin. Neurosci., 14 (6), pp. 563-568Keats, T.E., (1992) Atlas of normal roentgen variants that may simulate disease., , 5th edition. St. Louis, Mosby Year BookKeskil, S., Gözil, R., Calgüner, E., Common surgical pitfalls in the skull (2003) Surg. Neurol., 59 (3), pp. 228-231Kocaogullar, Y., Avci, E., Fossett, D., Caputy, A., The extradural subtemporal keyhole approach to the sphenocavernous region: Anatomic considerations (2003) Minim. Invas. 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(abstract)., 25 (1), p. 145Reis, C., Deshmukh, V., Zabramski, J.M., Crusius, M., Desmuskh, P., Spetzler, R.E., Preul, M.C., Anatomy of the mastoid emissary vein and venous system of the posterior neck region: Neurosurgical implications (2007) Neurosurg., 61, pp. ONS193-ONS201Reymond, J., Charuta, A., Wysocki, J., The morphology and morphometry of the foramina of the greater wing of the human sphenoid bone (2005) Folia Morphol., 64 (3), pp. 188-193Rossi, A.C., Freire, A.R., Prado, F.B., Caria, P.H.F., Botacin, P.R., Morphological characteristics of foramen of Vesalius and its relationship with clinical implications (2010) J. Morphol. Sci., 27 (1), pp. 26-29Shapiro, R., Robinson, F., The foramina of the middle fossa: A phylogenetic, anatomic and pathologic study (1967) Am. J. 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On Aharonov-Casher bound states

In this work bound states for the Aharonov-Casher problem are considered. According to Hagen's work on the exact equivalence between spin-1/2 Aharonov-Bohm and Aharonov-Casher effects, is known that the $\boldsymbol{\nabla}\cdot\mathbf{E}$ term cannot be neglected in the Hamiltonian if the spin of particle is considered. This term leads to the existence of a singular potential at the origin. By modeling the problem by boundary conditions at the origin which arises by the self-adjoint extension of the Hamiltonian, we derive for the first time an expression for the bound state energy of the Aharonov-Casher problem. As an application, we consider the Aharonov-Casher plus a two-dimensional harmonic oscillator. We derive the expression for the harmonic oscillator energies and compare it with the expression obtained in the case without singularity. At the end, an approach for determination of the self-adjoint extension parameter is given. In our approach, the parameter is obtained essentially in terms of physics of the problem.Comment: 11 pages, matches published versio

Dimensional Dependence of Black Hole Formation in Self-Similar Collapse of Scalar Field

We study classical and quantum self-similar collapses of a massless scalar field in higher dimensions, and examine how the increase in the number of dimensions affects gravitational collapse and black hole formation. Higher dimensions seem to favor formation of black hole rather than other final states, in that the initial data space for black hole formation enlarges as dimension increases. On the other hand, the quantum gravity effect on the collapse lessens as dimension increases. We also discuss the gravitational collapse in a brane world with large but compact extra dimensions.Comment: Improved a few arguments and added a figur