1,720,992 research outputs found
Extradural haematoma of posterior cranial fossa.
No full textTwo cases of extradural haematoma of posterior fossa with an acute course are reported. After trauma, the two patients did not show any symptom for a time of 16 and 18 hours respectively. Both of them showed a status of coma at the moment of hospitalization. The haematoma was diagnosed by CT scan. Both of them were immediately operated in order to evacuate the haematoma. Afterwards, one of the patients presented cerebellar symptoms while the other did not show any neurologic deficiency. The authors have analysed cases of this rare form of post-traumatic pathology referred in the literature since 1941, examining them from a clinical, therapeutic and prognostic point of view. The best diagnostic and therapeutic procedures to follow on this subject are then stressed
Ependymoblastoma. : a clinical review
No full textEpendymoblastoma is a malignant rarely reported neuroectodermal tumor. The authors describe a further case of cerebral ependymoblastoma and examine the clinical-prognostic aspects of this tumor in the light of the published data
Papillary Glioneuronal Tumor : Case Report and Literature Review.
No full textObjective and importance Papillary glioneuronal tumor is a recently described neoplasm composed of gliovascular pseudopapillae associated with intervening neuronal cells ranging from neurocytes to ganglion cells. This tumor is not currently included in the WHO classification of tumors of the central nervous system. We describe a new case of papillary glioneuronal tumor and analyze the data for a series of further 15 patients from international literature. Clinical presentation A 27-year-old man presented to us for generalized seizure. CT and MRI showed a cystic tumor with mural nodule in the left frontal lobe. Intervention Frontal craniotomy with gross total removal of the tumor was performed. Histopathological examination was positive for papillary glioneuronal tumor. Conclusion The clinical, radiologic, and pathological features of our case are strikingly similar to those of the previous reported cases. A review of the literature disclosed only 15 other cases of these tumors. It is important that every new case of PGNT is reported to allow its recognition and classification
Tuning of Surface-Acoustic-Wave Dispersion via Magnetically Modulated Contact Resonances
Full text linkIn this work, we propose the use of contact resonances, controlled via an external magnetic field, as a tunable platform to manipulate the dispersion of surface acoustic waves (SAWs). We exploit the analogy between surface acoustic waves in a semi-infinite medium and edge waves in a plate, to realize a compact experimental setup and to demonstrate our tuning strategy. The setup consists of a set of ferromagnetic bead resonators in contact with thin, permanent magnets and positioned at the free edge of an elastic plate. An additional set of magnets, placed at a controlled and variable distance from the beads, is used to alter the contact stiffness and natural frequencies of the bead resonators. We exploit resonances to open large-frequency band gaps via edge-wave hybridization and implement our tuning strategy to shift their frequency ranges. We predict the tuned dispersive properties of hybridized edge waves via numerical models and experimentally reconstruct them via laser vibrometry, finding excellent agreement. The use of magnetic interaction and contact mechanics as a tuning strategy for SAW systems could pave the way toward programmable devices for sensing and electronic components
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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