Schwannoma Of The Craniocervical Junction: Surgical Approach Of Two Cases

We report two cases of craniocervical junction schwannomas with a special focus on the surgical approach. The patients underwent a far-lateral approach in the sitting position that facilitated the lesion removal. This report is meant to improve the understanding of this surgical technique as well as improve awareness of its usefulness for similar cases.6103:00:00639641Baldwin, H., Christopher, G., The far lateral/combined supra- and infratentorial approach (1994) J Neurosurg, 81, pp. 60-68Oliveira, E., Rhoton A.L., Jr., Peace, D., Microsurgical anatomy of the region of the foramen magnum (1985) Surg Neurol, 24, pp. 293-352Salas, E., Sekhar, L.N., Ziyal, I.M., Caputy, A.J., Wright, D.C., Variations of the extreme-lateral craniocervical approach: Anatomical study and clinical analysis of 69 patients (1999) J Neurosurg, 90 (SPINE 2), pp. 206-219Martins, R.S., Suzuki, S.H., Sanematsu P., Jr., Plese, J.P.P., Acoustic neuroma in children without association with neurofibromatosis: Report of two cases (1999) Arq Neuropsiquiatr, 57, pp. 96-100Neto, P.M.A., Stamm, A.C., Braga, F.M., Mandibular trigeminal schwannoma: Case report (2001) Arq Neuropsiquiatr, 59, pp. 959-963Siqueira, M.G., Jennings, E., Moraes, O.J.S., Naso-ethmoid schwannoma with intracranial extension: Case report (2001) Arq Neuropsiquitr, 59, pp. 421-423Andrade, G.C., Neto, P.M.A., Braga, F.M., Thalamic intracerebral schwannoma: Case report (2002) Arq Neuropsiquiatr, 60, pp. 308-313Rhoton A.L., Jr., The far-lateral approach and its transcondylar, supracondylar, and paracondylar extensions (2000) Neurosurgery, 47, pp. 195-210Spetzler, R.F., Grahm, T.W., The far-lateral approach to file inferior clivus and the upper cervical region technical note (1990) BNI Quarterly, 6, pp. 35-38Samii, M., Klekamp, J., Carvalho, G., Surgical results for meningiomas of the craniocervical junction (1996) Neurosurgery, 39, pp. 1086-1095Al-Mefty, O., Borba, L.A.B., Aoki, N., Angtuaco, E., Pait, T.G., The transcondylar approach to extradural nonneoplastic lesions of the craniovertebral junction (1996) J Neurosurg, 84, pp. 1-6Bertalanffy, H., Seeger, W., The dorsolateral, suboccipital, transcondilar approach to the lower clivus and anterior portion of the craniocervical junction (1991) Neurosurgery, 29, pp. 815-82

A Geometric Approach to Massive p-form Duality

Massive theories of abelian p-forms are quantized in a generalized path-representation that leads to a description of the phase space in terms of a pair of dual non-local operators analogous to the Wilson Loop and the 't Hooft disorder operators. Special atention is devoted to the study of the duality between the Topologically Massive and the Self-Dual models in 2+1 dimensions. It is shown that these models share a geometric representation in which just one non local operator suffices to describe the observables.Comment: 26 pages, LaTeX. The discussion about the equivalence between the Proca model and two seldual models, with opposite spins, was eliminated. Typos correcte

Variation of growth performance of the striped venus clam Chamelea gallina (Mollusca: Bivalvia) (Linnaeus, 1758) in relation to environmental variables along the southern part of its geographic range

This study reports relative growth, shell length-age keys and growth performance indices (overall growth performance (OGP) and phi prime) for the striped venus Chamelea gallina from the Huelva coast in southwest (SW) Spain. The morphometric relationship shell height (SH)/shell length (SL) presented isometric growth whereas SL/shell width (SW) and SL/weight (W) displayed negative allometric growth. Shell length at age was estimated through length-frequency distribution (LF) and internal shell growth bands by acetate peel method (AP). C. gallina population consists mainly of three age classes with shell lengths around 13-15 mm for the first year, 25 mm for the second year and 30 mm for the third year. The OGP and phi prime values obtained in the present study are within the range of values for other C. gallina populations from the Gulf of Cádiz. Nevertheless, marked differences in growth performance were observed between populations from the Black Sea (lower growth performance) and from other locations along the southern distribution area of this species, which may be related to the low levels of temperature (SST), salinity (SSS) and chlorophyll-a (chl-a) concentration that exhibit large intra-annual fluctuations.En prensa0,371

High accuracy 234U(n,f) cross section in the resonance energy region

New results are presented of the 234U neutron-induced fission cross section, obtained with high accuracy in the resonance region by means of two methods using the 235U(n,f) as reference. The recent evaluation of the 235U(n,f) obtained with SAMMY by L. C. Leal et al. (these Proceedings), based on previous n-TOF data [1], has been used to calculate the 234U(n,f) cross section through the 234U/235U ratio, being here compared with the results obtained by using the n-TOF neutron flux

Measurement of the 240Pu(n,f) cross-section at the CERN n-TOF facility : First results from experimental area II (EAR-2)

The accurate knowledge of the neutron-induced fission cross-sections of actinides and other isotopes involved in the nuclear fuel cycle is essential for the design of advanced nuclear systems, such as Generation-IV nuclear reactors. Such experimental data can also provide the necessary feedback for the adjustment of nuclear model parameters used in the evaluation process, resulting in the further development of nuclear fission models. In the present work, the 240Pu(n,f) cross-section was measured at CERN's n-TOF facility relative to the well-known 235U(n,f) cross section, over a wide range of neutron energies, from meV to almost MeV, using the time-of-flight technique and a set-up based on Micromegas detectors. This measurement was the first experiment to be performed at n-TOF's new experimental area (EAR-2), which offers a significantly higher neutron flux compared to the already existing experimental area (EAR-1). Preliminary results as well as the experimental procedure, including a description of the facility and the data handling and analysis, are presented

Characterization of the n-TOF EAR-2 neutron beam

The experimental area 2 (EAR-2) at CERNs neutron time-of-flight facility (n-TOF), which is operational since 2014, is designed and built as a short-distance complement to the experimental area 1 (EAR-1). The Parallel Plate Avalanche Counter (PPAC) monitor experiment was performed to characterize the beam prole and the shape of the neutron 'ux at EAR-2. The prompt γ-flash which is used for calibrating the time-of-flight at EAR-1 is not seen by PPAC at EAR-2, shedding light on the physical origin of this γ-flash

New measurement of the 242Pu(n,γ) cross section at n-TOF-EAR1 for MOX fuels : Preliminary results in the RRR

The spent fuel of current nuclear reactors contains fissile plutonium isotopes that can be combined with 238U to make mixed oxide (MOX) fuel. In this way the Pu from spent fuel is used in a new reactor cycle, contributing to the long-term sustainability of nuclear energy. The use of MOX fuels in thermal and fast reactors requires accurate capture and fission cross sections. For the particular case of 242Pu, the previous neutron capture cross section measurements were made in the 70's, providing an uncertainty of about 35% in the keV region. In this context, the Nuclear Energy Agency recommends in its "High Priority Request List" and its report WPEC-26 that the capture cross section of 242Pu should be measured with an accuracy of at least 7-12% in the neutron energy range between 500 eV and 500 keV. This work presents a brief description of the measurement performed at n-TOF-EAR1, the data reduction process and the first ToF capture measurement on this isotope in the last 40 years, providing preliminary individual resonance parameters beyond the current energy limits in the evaluations, as well as a preliminary set of average resonance parameters