Heat flow in southernmost California and the origin of the Salton Trough

Heat flow in the Imperial Valley and adjacent crystalline rocks is very high (∼140 mW m−2). Gravity and seismic studies suggest the crust is about 23.5 km thick with the lower half composed of gabbro and the upper fourth composed of low-density sediments. Conduction through such a crust resting directly on asthenosphere would give the observed heat flow if there were no extension or sedimentation. However, both processes must have been active, as the Imperial Valley is part of the Salton Trough, a pull-apart sedimentary basin that evolved over the past 4 or 5 m.y. To investigate the interrelations of these factors, we consider a one-dimensional model of basin formation in which the lower crustal gabbro and upper crustal sediments accumulated simultaneously as the crust extended and sedimentation kept pace with isostatic subsidence. For parameters appropriate for the Salton Trough, increasing the extension rate has little effect on surface heat flow because it increases effects of heating by intrusion and cooling by sedimentation in a compensating manner; it does, however, result in progressively increasing lower crustal temperatures. Analytical results suggest that the average extensional strain rate during formation of the trough was ∼20–50%/m.y. (∼1014 s−1); slower rates are inadequate to account for the present composition of the crust, and faster rates would probably cause massive crustal melting. To achieve the differential velocities of the Pacific plate at one end of the trough and North American plate at the other with this strain rate, extension must have, on the average, been distributed (or shifted about) over a spreading region ∼150 km wide. This is about 10 times wider than the present zone of active seismicity, suggesting that the seismic pattern is ephemeral on the time scale for the trough's formation. Narrow spreading zones are typical where sustained spreading is compensated by basaltic intrusion to form the thin oceanic crust, but where such spreading occurs in thicker continental crust, broader zones of distributed extension (with smaller strain rates) may be required for heat balance. The Salton Trough model suggests that distributed extension can be associated with substantial magmatic additions to the crust; their effect on crustal buoyancy has important implications for the relation between crustal extension and subsidence

Processing Queries in a Large Peer-to-Peer System

Abstract. While current search engines seem to easily handle the size of the data available on the Internet, they cannot provide fresh results. The most up-to-date data always resides on the data sources. Efficiently interconnecting data providers, however, is not an easy problem. Peer-to-peer computing is the latest technology to address this problem. However, efficient query processing in peer-to-peer networks remains an open research area. In this paper, we present a performance study of a system that facilitates efficient searches of large numbers of independent data providers on the Internet. In our scenario, each data provider becomes an autonomous node in a large peer-to-peer system. Using small indices on each node, we can efficiently direct queries submitted on any node to the relevant sources. Experiments with a large peer-to-peer network demonstrate the feasibility of our approach.

Clear cell sarcoma of the scapula. A case report and review of the literature

BACKGROUND: Clear cell sarcoma of tendons and aponeuroses (CCSTA) appears usually in the extremities and rarely in the trunk. CASE PRESENTATION: We present an unusual case of CCSTA overlying the scapular region and with secondary osseous extension in the lower scapula. The patient underwent a wide local excision with removal of the tumor and the lower two thirds of the scapula. He had no local recurrences but he developed lung metastases after 5 months in spite of postoperative chemotherapy. He finally died ten months later. CONCLUSION: The patients with CCSTA have a variable unpredictable course. Despite treatment the overall prognosis is poor

Unusual patterns of Monteggia fracture-dislocation

BACKGROUND: High-energy trauma may result in uncommon open injuries around the elbow joint. The management of these injuries can be difficult. CASE DESCRIPTION: Fourteen patients were treated between 1999 and 2003 and their injuries consisted of Monteggia fracture-dislocations combined with segmental fractures of the ulna or fractures of the forearm bones and/or various more complex trauma such as neural injuries, bone comminution and severe soft tissue injuries around the elbow. Eight of them (57%) were multiply injured with severe additional injuries. All patients underwent surgery within first 4–6 hours. Internal fixation, external fixation or a combination of both methods were used to stabilize fractures while open wounds had secondary closure. RESULTS: Additional operations were required in 6 patients. The functional results according to the Mayo Elbow Performance Index were excellent or good in eleven patients, and fair or poor in the remaining three. The patients with fair and poor results had suffered from severe neural and soft tissue trauma and/or multiple fractures of the upper extremity. CONCLUSION: These injuries should be treated as an emergency. The surgeon should apply any available method that can provide stability to the bone fragments and safe handling of the soft tissues giving priority to internal fixation of the fractures. Severe osseous, soft tissue and neural trauma affect the functional results of the elbow region

Recherche et dénombrement des Escherichia coli dans les produits carnés. Emploi de la Gélose au Désoxycholate de sodium à température d incubation de 44°

Pantaléon Jean, Galanis N., Guibert M. Recherche et dénombrement des Escherichia coli dans les produits carnés. Emploi de la Gélose au Désoxycholate de sodium à température d'incubation de 44°. In: Bulletin de l'Académie Vétérinaire de France tome 112 n°8, 1959. pp. 467-471

Nonequilibrium steady states in a vibrated-rod monolayer: tetratic, nematic and smectic correlations

We study experimentally the nonequilibrium phase behaviour of a horizontal monolayer of macroscopic rods. The motion of the rods in two dimensions is driven by vibrations in the vertical direction. Aside from the control variables of packing fraction and aspect ratio that are typically explored in molecular liquid crystalline systems, due to the macroscopic size of the particles we are also able to investigate the effect of the precise shape of the particle on the steady states of this driven system. We find that the shape plays an important role in determining the nature of the orientational ordering at high packing fraction. Cylindrical particles show substantial tetratic correlations over a range of aspect ratios where spherocylinders have previously been shown by Bates et al (JCP 112, 10034 (2000)) to undergo transitions between isotropic and nematic phases. Particles that are thinner at the ends (rolling pins or bails) show nematic ordering over the same range of aspect ratios, with a well-established nematic phase at large aspect ratio and a defect-ridden nematic state with large-scale swirling motion at small aspect ratios. Finally, long-grain, basmati rice, whose geometry is intermediate between the two shapes above, shows phases with strong indications of smectic order.Comment: 18 pages and 13 eps figures, references adde

Current trends in the management of extra-abdominal desmoid tumours

Extra-abdominal desmoid tumours are slow-growing, histologically benign tumours of fibroblastic origin with variable biologic behaviour. They are locally aggressive and invasive to surrounding anatomic structures. Magnetic resonance imaging is the modality of choice for the diagnosis and the evaluation of the tumours. Current management of desmoids involves a multidisciplinary approach. Wide margin surgical resection remains the main treatment modality for local control of the tumour. Amputation should not be the initial treatment, and function-preserving procedures should be the primary treatment goal. Adjuvant radiation therapy is recommended both for primary and recurrent lesions. Chemotherapy may be used for recurrent or unresectable disease. Overall local recurrence rates vary and depend on patient's age, tumour location and margins at resection