200 research outputs found

    The Lateral Torsional Buckling Strength of Cold-formed Stainless Steel Beams

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    The findings of an investigation of the lateral torsional buckling strength of cold-formed stainless steel beams are reported in this study. The sections under consideration are cold-formed lipped channel sections spot-welded back to back to form doubly-symmetric lipped I-beams. The beams were fabricated from a modified AISI Type 409 stainless steel, designated Type 3CR12 corrosion resisting steel. The purpose of this study is to compare the experimental lateral torsional buckling strengths of doubly-symmetric beams to the theoretical predictions proposed by the ASCE Specification for the Design of Cold-Formed Stainless Steel Structural Members. It was concluded in this investigation that an acceptable prediction of beam strength may be obtained through the use of the tangent modulus approach adopted in the ASCE stainless steel design specification

    The Lateral Torsional Buckling Strength of Cold-formed Stainless Steel Lipped Channel Beams

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    The findings of an investigation into the lateral buckling strength of cold-formed singly-symmetric stainless steel beams are reported in this study. The singly-symmetric sections under consideration were lipped channel sections fabricated from a modified AISI stainless steel Type 409 designated 3CR12, a ferritic corrosion resisting steel. The purpose of this study was to compare the experimental strengths of singly-symmetric sections to the theoretical predictions proposed by the new ASCE Specification for the Design of Cold-Formed Stainless Steel Structural Members. It was concluded in this investigation that the tangent modulus approach adopted in the design specification for stainless steels, compared well with the experimental results

    Landscape history, time lags and drivers of change : urban natural grassland remnants in Potchefstroom, South Africa

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    The history of the landscape directly affects biotic assemblages, resulting in time lags in species response to disturbances. In highly fragmented environments, this phenomenon often causes extinction debts. However, few studies have been carried out in urban settings. To determine if there are time lags in the response of temperate natural grasslands to urbanization. Does it differ for indigenous species and for species indicative of disturbance and between woody and open grasslands? Do these time lags change over time? What are the potential landscape factors driving these changes? What are the corresponding vegetation changes? In 1995 and 2012 vegetation sampling was carried out in 43 urban grassland sites. We calculated six urbanization and landscape measures in a 500 m buffer area surrounding each site for 1938, 1961, 1970, 1994, 1999, 2006, and 2010. We used generalized linear models and model selection to determine which time period best predicted the contemporary species richness patterns. Woody grasslands showed time lags of 20-40 years. Contemporary open grassland communities were, generally, associated with more contemporary landscapes. Altitude and road network density of natural areas were the most frequent predictors of species richness. The importance of the predictors changed between the different models. Species richness, specifically, indigenous herbaceous species, declined from 1995 to 2012. The history of urbanization affects contemporary urban vegetation assemblages. This indicates potential extinction debts, which have important consequences for biodiversity conservation planning and sustainable future scenarios.Peer reviewe

    Development of Sensory, Motor and Behavioral Deficits in the Murine Model of Sanfilippo Syndrome Type B

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    BACKGROUND: Mucopolysaccharidosis (MPS) IIIB (Sanfilippo Syndrome type B) is caused by a deficiency in the lysosomal enzyme N-acetyl-glucosaminidase (Naglu). Children with MPS IIIB develop disturbances of sleep, activity levels, coordination, vision, hearing, and mental functioning culminating in early death. The murine model of MPS IIIB demonstrates lysosomal distention in multiple tissues, a shortened life span, and behavioral changes. PRINCIPAL FINDINGS: To more thoroughly assess MPS IIIB in mice, alterations in circadian rhythm, activity level, motor function, vision, and hearing were tested. The suprachiasmatic nucleus (SCN) developed pathologic changes and locomotor analysis showed that MPS IIIB mice start their daily activity later and have a lower proportion of activity during the night than wild-type controls. Rotarod assessment of motor function revealed a progressive inability to coordinate movement in a rocking paradigm. Purkinje cell counts were significantly reduced in the MPS IIIB animals compared to age matched controls. By electroretinography (ERG), MPS IIIB mice had a progressive decrease in the amplitude of the dark-adapted b-wave response. Corresponding pathology revealed shortening of the outer segments, thinning of the outer nuclear layer, and inclusions in the retinal pigmented epithelium. Auditory-evoked brainstem responses (ABR) demonstrated progressive hearing deficits consistent with the observed loss of hair cells in the inner ear and histologic abnormalities in the middle ear. CONCLUSIONS/SIGNIFICANCE: The mouse model of MPS IIIB has several quantifiable phenotypic alterations and is similar to the human disease. These physiologic and histologic changes provide insights into the progression of this disease and will serve as important parameters when evaluating various therapies

    Phase II study of weekly oxaliplatin plus infusional fluorouracil and folinic acid (FUFOX regimen) as first-line treatment in metastatic gastric cancer

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    Oxaliplatin plus fluorouracil/folinic acid (5-FU/FA) every 2 weeks has shown promising activity in advanced gastric cancer. This study assessed the efficacy and safety of weekly oxaliplatin plus 5-FU/FA (FUFOX regimen) in the metastatic setting. Patients with previously untreated metastatic gastric cancer received oxaliplatin (50 mg m−2) plus FA (500 mg m−2, 2-h infusion) followed by 5-FU (2000 mg m−2, 24-h infusion) given on days 1, 8, 15 and 22 of a 5-week cycle. The primary end point of this multicentre phase II study was the response rate according to RECIST criteria. A total of 48 patients were enrolled. Median age was 62 years and all patients had metastatic disease, with a median number of three involved organs. The most common treatment-related grade 3/4 adverse events were diarrhoea (17%), deep vein thrombosis (15%), neutropenia (8%), nausea (6%), febrile neutropenia (4%), fatigue (4%), anaemia (4%), tumour bleeding (4%), emesis (2%), cardiac ischaemia (2%) and pneumonia (2%). Grade 1/2 sensory neuropathy occurred in 67% of patients but there were no episodes of grade 3 neuropathy. Intent-to-treat analysis showed a response rate of 54% (95% CI, 39–69%), including two complete responses. At a median follow-up of 18.1 months (range 11.2–26.2 months), median survival is 11.4 months (95% CI, 8.0–14.9 months) and the median time to progression is 6.5 months (95% CI, 3.9–9.2 months). The weekly FUFOX regimen is well tolerated and shows notable activity as first-line treatment in metastatic gastric cancer
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