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Major Structures (major + structure)

Distribution by Scientific Domains

Medical Sciences	42%
Life Sciences	28%

Selected Abstracts

The role of soil in the collapse of 18 piers of Hanshin Expressway in the Kobe earthquake

EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 5 2006
George Mylonakis
Abstract An investigation is presented of the collapse of a 630 m segment (Fukae section) of the elevated Hanshin Expressway during the 1995 Kobe earthquake. The earthquake has, from a geotechnical viewpoint, been associated with extensive liquefactions, lateral soil spreading, and damage to waterfront structures. Evidence is presented that soil,structure interaction (SSI) in non-liquefied ground played a detrimental role in the seismic performance of this major structure. The bridge consisted of single circular concrete piers monolithically connected to a concrete deck, founded on groups of 17 piles in layers of loose to dense sands and moderate to stiff clays. There were 18 spans in total, all of which suffered a spectacular pier failure and transverse overturning. Several factors associated with poor structural design have already been identified. The scope of this work is to extend the previous studies by investigating the role of soil in the collapse. The following issues are examined: (1) seismological and geotechnical information pertaining to the site; (2) free-field soil response; (3) response of foundation-superstructure system; (4) evaluation of results against earlier studies that did not consider SSI. Results indicate that the role of soil in the collapse was multiple: First, it modified the bedrock motion so that the frequency content of the resulting surface motion became disadvantageous for the particular structure. Second, the compliance of soil and foundation altered the vibrational characteristics of the bridge and moved it to a region of stronger response. Third, the compliance of the foundation increased the participation of the fundamental mode of the structure, inducing stronger response. It is shown that the increase in inelastic seismic demand in the piers may have exceeded 100% in comparison with piers fixed at the base. These conclusions contradict a widespread view of an always-beneficial role of seismic SSI. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Anterior cranial base reconstruction using free tissue transfer: Changing trends,

HEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 2 2003
Joseph Califano MD
Abstract Introduction. A consecutive series of 135 patients undergoing resection for malignant tumors involving the anterior cranial base between 1976 and 1999 was reviewed. Patient and Methods. In the years from 1976,1991, free-tissue transfer was used in 5 of 76 or 6.6% of cases, whereas free-tissue reconstruction was used in 24 of 59 or 40% of cases in the years 1992,1999. Of those cases reconstructed with free-tissue transfer in 1976,1991, 60% (three of five) underwent a complex resection defined as involving dura, brain, or more than one major structure adjacent to skull base. Of those patients reconstructed with conventional (pericranial or pericranial/galeal) pedicled flaps in this time period, 35% (25 of 71) underwent a complex resection. From 1992,1999, 75% (18 of 24) of patients reconstructed with free-tissue transfer received a complex resection, whereas only 6% (2 of 35) of patients reconstructed by other means received a complex resection. Outcomes. For those patients reconstructed by free-tissue transfer, there were no instances of flap loss. Comparison of these two time periods was notable for a similar patient composition in terms of age, histologic findings, and extent of resection. Major complication rates for patients who are reconstructed with free-tissue transfer for anterior cranial base resections (31%) are similar compared with patients who have been reconstructed with conventional pedicled flaps (35%). This was noted despite an increased extent and complexity of resection in those patients who underwent free-tissue transfer reconstruction (72%) compared with those patients reconstructed by more conventional means (26%) p < .001. Conclusion. In our institution, the use of vascularized, free-tissue transfer has replaced pedicled flaps as the preferred modality for reconstructing complex anterior cranial base defects involving resection of dura, brain, or multiple major structures adjacent to local skull base, including the orbit, palate, and other structures. Complication rates for patients reconstructed with free-tissue transfer techniques is similar to those patients reconstructed by conventional techniques, despite an increase in complexity of resection in this group. © 2002 Wiley Periodicals, Inc. Head Neck 24: 000,000, 2002 [source]

Receptor for the globular heads of C1q (gC1q-R, p33, hyaluronan-binding protein) is preferentially expressed by adenocarcinoma cells

INTERNATIONAL JOURNAL OF CANCER, Issue 5 2004
Daniel B. Rubinstein
Abstract Combinatorial Ig libraries with phage display allow in vitro generation of human Ig fragments without the need to maintain hybridomas in ongoing cell culture or to select circulating Ig from human serum. Identifying tumor-associated antigens on the surface of intact tumor cells, as opposed to purified proteins, presents a challenge due to the difficulty of preserving complex 3-D epitopic sites on the cell surface, the variable expression of antigens on different malignant cell types and the stereotactic interference of closely associated proteins on the intact membrane surface limiting accessibility to antigenic sites. A combinatorial Ig library of 1010 clones was generated from the cDNA of PBMCs derived from patients with breast adenocarcinoma. Following subtractive panning, the library was enriched for Ig (Fab fragment) binding to intact adenocarcinoma cells and the resultant Fabs were screened against a cDNA expression library, itself generated from breast cancer cells. Using this approach, we isolated clones from the cDNA library expressing gC1q-R, a glycoprotein comprising the major structure of C1, the first component of the complement system. gC1q-R is a 33 kDa glycoprotein expressed not only on the cell surface but also intracellularly, with motifs that target it to mitochondria and complete homology with HABP and human HeLa cell protein p32, which is copurified with pre-mRNA SF2. Sequencing of the gene encoding tumor-associated gC1q-R did not reveal any consistent tumor-specific mutations. However, histochemical staining with anti-gC1q-R MAb demonstrated marked differential expression of gC1q-R in thyroid, colon, pancreatic, gastric, esophageal and lung adenocarcinomas compared to their nonmalignant histologic counterparts. In contrast, differential expression was not seen in endometrial, renal and prostate carcinomas. Despite high expression in breast carcinoma, gC1q-R was also expressed in nonmalignant breast tissue. Although the precise relation of gC1q-R to carcinogenesis remains unclear, our finding of tumor overexpression and the known multivalent binding of gC1q-R to not only C1q itself but also a variety of circulating plasma proteins as well as its involvement in cell-to-cell interactions suggest that gC1q-R may have a role in tumor metastases and potentially serve in molecule-specific targeting of malignant cells. © 2004 Wiley-Liss, Inc. [source]

Review of animal models for autism: implication of thyroid hormone

CONGENITAL ANOMALIES, Issue 1 2006
Miyuki Sadamatsu
ABSTRACT,, Autism is a behaviorally defined disorder associated with characteristic impairments in social interactions and communication, as well as restricted and repetitive behaviors and interest. Its prevalence was once thought to be 2/10 000, but recently several large autism prevalence reviews revealed that the rate of occurrence was roughly 30/10 000. While it has been considered a developmental disorder, little is certain about its etiology. Neuroanatomical studies at the histological level in the brains of autistic patients provide many arguments in the etiology of autism. Results from postmortem and imaging studies have implicated many major structures of the brain including the limbic system, cerebellum, corpus callosum, basal ganglia and brainstem. There is no single biological or clinical marker for autism. While several promising candidate genes have been presented, the critical loci are yet unknown. Environmental influences such as rubella virus, valproic acid, and thalidomide exposure during pregnancy are also considered important, as concordance in monozygotic twins is less than 100% and the phenotypic expression of the disorder varies widely. It is thus hypothesized that non-genetic mechanisms contribute to the onset of autistic syndrome. In light of these ambiguities, hope is held that an animal model of autism may help elucidate matters. In this article, we overview most of the currently available animal models for autism, and propose the rat with mild and transient neonatal hypothyroidism as a novel model for autism. [source]

Anterior cranial base reconstruction using free tissue transfer: Changing trends,

Dynamic modelling of passive margin salt tectonics: effects of water loading, sediment properties and sedimentation patterns

BASIN RESEARCH, Issue 3 2005
Lykke Gemmer
We investigate the evolution of passive continental margin sedimentary basins that contain salt through two-dimensional (2D) analytical failure analysis and plane-strain finite-element modelling. We expand an earlier analytical failure analysis of a sedimentary basin/salt system at a passive continental margin to include the effects of submarine water loading and pore fluid pressure. Seaward thinning sediments above a weak salt layer produce a pressure gradient that induces Poiseuille flow in the viscous salt. We determine the circumstances under which failure at the head and toe of the frictional,plastic sediment wedge occurs, resulting in translation of the wedge, landward extension and seaward contraction, accompanied by Couette flow in the underlying salt. The effects of water: (i) increase solid and fluid pressures in the sediments; (ii) reduce the head to toe differential pressure in the salt and (iii) act as a buttress to oppose failure and translation of the sediment wedge. The magnitude of the translation velocity upon failure is reduced by the effects of water. The subsequent deformation is investigated using a 2D finite-element model that includes the effects of the submarine setting and hydrostatic pore pressures. The model quantitatively simulates a 2D approximation of the evolution of natural sedimentary basins on continental margins that are formed above salt. Sediment progradation above a viscous salt layer results in formation of landward extensional basins and listric normal growth faults as well as seaward contraction. At a later stage, an allochthonous salt nappe overthrusts the autochthonous limit of the salt. The nature and distribution of major structures depends on the sediment properties and the sedimentation pattern. Strain weakening of sediment favours landward listric growth faults with formation of asymmetric extensional depocentres. Episodes of low sediment influx, with partial infill of depocentres, produce local pressure gradients in the salt that result in diapirism. Diapirs grow passively during sediment aggradation. [source]

The "safe zone" in medial percutaneous calcaneal pin placement

CLINICAL ANATOMY, Issue 4 2009
Zakareya Gamie
Abstract Percutaneous pin insertion into the medial calcaneus places a number of structures at risk. Evidence suggests that the greatest risk is to the medial calcaneal nerve (MCN). The medial calcaneal region of 24 cadavers was dissected to determine the major structures at risk. By using four palpable anatomical landmarks, the inferior tip of the medial malleolus (point A), the posterior superior portion of the calcaneal tuberosity (point B), the navicular tuberosity (point C), and the medial process of the calcaneal tuberosity (point D), we attempted to define the safe zone taking into account all possible variables in our dissections including ankle position, side, gender, and possible anatomical variations of the MCN. The commonest arrangement of the MCN was two MCNs that arose independently, one arising before the bifurcation of the tibial nerve and the other arising from the medial plantar nerve. A zone could be defined posterior to 75% of the distance along the lines AB, CD, AD, and CB which would avoid most structures. The posterior branches of the MCN, however, would still be at risk and placing the pin too far posteriorly risks an avulsion fracture. This is the first study to employ four palpable anatomical landmarks to identify a zone to minimize damage to neurovascular structures. It may not be possible, however, to avoid injury of the MCN and consequent sensory loss to the sole of the foot. foot. Clin. Anat. 22:523,529, 2009. © 2009 Wiley-Liss, Inc. [source]