Shape of Deconstruction

We construct a six-dimensional Maxwell theory using a latticized extra space, the continuum limit of which is a shifted torus recently discussed by Dienes. This toy model exhibits the correspondence between continuum theory and discrete theory, and give a geometrical insight to theory-space model building.Comment: 10 pages, 2 figures, RevTeX4. a citation adde

Kinetic response of ionospheric ions to onset of auroral electric fields

Examination of the exact analytic solution of a kinetic model of collisional interaction of ionospheric fions with atmospheric neutrals in the Bhatnagar-Gross-Krook approximation, shows that the onset of intense auroral electric fields in the topside ionosphere can produce the following kinetic effects: (1) heat the bulk ionospheric ions to approximately 2 eV, thus driving them up to higher altitudes where they can be subjected to collisionless plasma processes; (2) produce a nonMaxwellian superthermal tail in the distribution function; and (3) cause the ion distribution function to be anisotropic with respect to the magnetic field with the perpendicular average thermal energy exceeding the parallel thermal energy

Kondo Effect in Fermi Systems with a Gap: A Renormalization Group Study

We present the results of a Wilson Renormalization Group study of the single-impurity Kondo and Anderson models in a system with a gap in the conduction electron spectrum. The behavior of the impurity susceptibility and the zero-frequency response function, $T>$ are discussed in the cases with and without particle-hole symmetry. In addition, for the asymmetric Anderson model the correlation functions, $<\vec S \cdot\vec \sigma (0)>$,$$, and$$ are computed.Comment: 10 pages, 10 figure

Theory of the Three-Group Evolutionary Minority Game

Based on the adiabatic theory for the evolutionary minority game (EMG) that we proposed earlier[1], we perform a detail analysis of the EMG limited to three groups of agents. We derive a formula for the critical point of the transition from segregation (into opposing groups) to clustering (towards cautious behaviors). Particular to the three-group EMG, the strategy switching in the "extreme" group does not occur at every losing step and is strongly intermittent. This leads to an correction to the critical value of the number of agents at the transition, $N_c$. Our expression for $N_c$ is in agreement with the results obtained from our numerical simulations.Comment: 4 pages and 2 figure

Decompression of cavernous sinus meningioma for preservation and improvement of cranial nerve function

Journal ArticleMeningiomas are the most common tumors affecting the cavernous sinus (CS). Despite advances in microsurgery and radiosurgery, treatment of CS meningiomas remains difficult and controversial. As in cases of other meningiomas, the goal of treatment for CS meningioma is long-term growth control and preservation of neural function. Gross-total resection, the ideal treatment for meningioma, is not always possible to obtain in patients with CS meningiomas with an acceptable level of morbidity. Therefore, microsurgery and radiosurgery have recently been advocated as a combined therapy to achieve good control of tumor growth and favorable functional outcome. The authors describe a technique in which tumor volume can be reduced to a minimal residual amount, while preserving cranial nerve function. This enables the smallest field to be treated radiosurgically. The optic nerve is decompressed, and the tumor mass is reduced to provide at least a 5-mm interpositional distance between the optic nerve and the residual lesion. Direct decompression of the CS, with opening of the lateral and superior sinus walls, and piecemeal removal of the tumor in "safe" locations are performed to facilitate an improvement in cranial nerve function. The authors describe the use of this technique in a series of patients and demonstrate improvement of cranial nerve function in a subset of these patients

The JPL telerobot operator control station. Part 1: Hardware

The Operator Control Station of the Jet Propulsion Laboratory (JPL)/NASA Telerobot Demonstrator System provides the man-machine interface between the operator and the system. It provides all the hardware and software for accepting human input for the direct and indirect (supervised) manipulation of the robot arms and tools for task execution. Hardware and software are also provided for the display and feedback of information and control data for the operator's consumption and interaction with the task being executed. The hardware design, system architecture, and its integration and interface with the rest of the Telerobot Demonstrator System are discussed

Posterior fossa brain tumors and arterial hypertension

ManuscriptHypertension caused by arterial compression of the rostral ventrolateral medulla is well described. Much less information is available on the association between neurogenic hypertension and posterior fossa brain tumors. To date, multiple reports have supported the impression that a small subpopulation of patients with posterior fossa tumors can present with arterial hypertension, and many of those patients achieved significant improvement of their hypertension after tumor resection and medullary decompression. To review the relationship between posterior fossa brain tumors and hypertension, we detail the history, basic science, and clinical reports along with an illustrative case regarding this topic

Carotid artery-sparing repair of a cavernous carotid artery pseudoaneurysm

Journal ArticleCarotid artery (CA) injury after transsphenoidal and endoscopic sinus surgery is a well-recognized but fortunately rare complication.1 It is associated with significant morbidity and mortality rates5 and is more common in cases of repeated surgery, cavernous sinus invasion, prior radiotherapy, and anatomical anomalies of the sphenoid and cavernous sinuses.4 It usually results in CA stenosis, occlusion, or pseudoaneurysm formation followed by serious complications, such as stroke and caroticocavernous fistulas.5 Direct surgical repair is difficult, and treatment may require parent vessel sacrifice and possibly vascular bypass.5 We describe the successful treatment of a cavernous? CA pseudoaneurysm with a novel CA-sparing approach. This 62-year-old woman with recurrent esthesioneuroblastoma underwent endoscopic tumor resection. A CA injury occurred intraoperatively. Hemostasis was rapidly achieved by packing the bleeding site with cottonoid and packing strip gauze within the sphenoid sinus. Postoperative angiography performed immediately after surgery revealed a 2-mm pseudoaneurysm at the anterior genu of the left cavernous internal CA (ICA) with minimal stenosis (Fig. 1 left). Eight days after the initial arterial injury, repeat angiography demonstrated persistence of the aneurysm. To repair the arterial defect and preserve the CA, an endovascular stent was placed across the puncture site to restore its normal caliber and to provide a buttressing surface for surgical repair by graft apposition (Fig. 1 right). Subsequently, with the aid of the operating microscope, a small piece of autologous fascia lata graft was placed directly over the arterial puncture site via a transnasal?transsphenoidal approach and bound using BioGlue (CryoLife, Inc., Kennesaw, GA), a two-component (bovine serum albumin and glutaraldehyde) surgical adhesive that is used as an adjunct to open surgical repair of large vessels, such as the aorta, femoral artery, and CA.2 The fascia lata graft was placed over the puncture site to patch the hole in the arterial wall directly because the pseudoaneurysm remained and was unchanged after stent placement alone, presumably because of the interstices of the stent

Resolution of an anterior-inferior cerebellar artery feeding aneurysm with the treatment of a transverse-sigmoid dural arteriovenous fistula

ManuscriptThe authors describe a 27-year old man who developed an unruptured anterior-inferior cerebellar artery feeding aneurysm from a transverse-sigmoid dAVF and its subsequent resolution with the treatment of the dAVF. The patient, with a known history of left transverse and sigmoid sinus thrombosis, presented with pulse-synchronous tinnitus. Angiography revealed an extensive dAVF, with feeders from both the extracranial and intracranial circulations, involving the right transverse sinus, the torcula, and the left transverse/sigmoid sinuses. Multimodal endovascular and open surgical therapy was employed. Prior to a planned second-stage treatment for the left sigmoid sinus component, the dAVF improved significantly, but a small flow-related aneurysm developed on the left AICA feeding the petrous dural region in the interval. Resection of the involved sigmoid sinus resulted in resolution of the aneurysm. This is the first reported case of an unruptured feeding-artery aneurysm in an intracranial dAVF that resolved spontaneously with the treatment of the dAVF. Until more is known about its natural history, the decision on when and whether to treat an unruptured dAVF feedingartery aneurysm must be made on an individual basis