Observations on the vibration of axially-tensioned elastomeric pipes conveying fluids

A study of the effect of axial tension on the vibration of a single-span elastomeric pipe clamped at both ends conveying fluid has been carried out both experimentally and theoretically. A new mathematical model using a penalty function technique and the method of kinematic correction and fictitious loads has been developed. The influence of flowing fluid and axial tension on natural frequencies and mode shapes of the system has been described using this model and compared with experimental observations. Linear and non-linear dynamic response of the harmonically excited pipe has also been investigated for varying flow velocities and initial axial tensions

The Impact of Temperature on Physical Activity Levels During a 12-Week Walking Intervention

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Induction of Colonic Aberrant Crypts in Mice by Feeding Apparent N-Nitroso Compounds Derived From Hot Dogs

Nitrite-preserved meats (e.g., hot dogs) may help cause colon cancer because they contain N-nitroso compounds. We tested whether purified hot-dog-derived total apparent N-nitroso compounds (ANC) could induce colonic aberrant crypts, which are putative precursors of colon cancer. We purified ANC precursors in hot dogs and nitrosated them to produce ANC. In preliminary tests, CF1 mice received 1 or 3 i.p. injections of 5mg azoxymethane (AOM)/kg. In Experiments 1 and 2, female A/J mice received ANC in diet. In Experiment 1, ANC dose initially dropped sharply because the ANC precursors had mostly decomposed but, later in Experiment 1 and throughout Experiment 2, ANC remained at 85 nmol/g diet. Mice were killed after 8 (AOM tests) or 17–34 (ANC tests) wk.Median numbers of aberrant crypts in the distal 2 cm of the colon for 1 and 3 AOMinjections, CF1 controls, ANC (Experiment 1), ANC (Experiment 2),and untreated A/J mice were 31, 74, 12, 20, 12, and 5–6, with P < 0.01 for both ANC tests. Experiment 2 showed somewhat increased numbers of colonic mucin-depleted foci in the ANC-treated group. We conclude that hot-dog-derived ANC induced significant numbers of aberrant crypts in the mouse colon

Application of reliability-based robustness assessment of steel moment resisting frame structures under post-mainshock cascading events

This paper proposes a reliability-based framework for quantifying structural robustness considering the occurrence of a major earthquake (mainshock) and subsequent cascading hazard events, such as aftershocks that are triggered by the mainshock. These events can significantly increase the probability of failure of buildings, especially for structures that are damaged during the mainshock. The application of the proposed framework is exemplified through three numerical case studies. The case studies correspond to three SAC steel moment frame buildings of three, nine, and 20 stories, which were designed to pre-Northridge codes and standards. Two-dimensional nonlinear finite-element models of the buildings are developed with the Open System for Earthquake Engineering Simulation framework (OpenSees), using a finite length plastic hinge beam model and a bilinear constitutive law with deterioration, and are subjected to multiple mainshock-aftershock seismic sequences. For the three buildings analyzed herein, it is shown that the structural reliability under a single seismic event can be significantly different from that under a sequence of seismic events. The reliability based robustness indicator shows that the structural robustness is influenced by the extent to which a structure can distribute damage

Longitudinal Assessment of Gray and White Matter in Chronic Schizophrenia: A Combined Diffusion-Tensor and Structural Magnetic Resonance Imaging Study

Previous studies have reported continued focal gray matter loss after the clinical onset of schizophrenia. Longitudinal assessments in chronic illness, of white matter in particular, have been less conclusive

Comparative Assessment of Soil-Structure Interaction Regulations of ASCE 7-16 and ASCE 7-10

This paper evaluates the consequences of practicing soil structure interaction (SSI) regulations of ASCE 7-16 on seismic performance of building structures. The motivation for this research stems from the significant changes in the new SSI provisions of ASCE 7-16 compared to the previous 2010 edition. Generally, ASCE 7 considers SSI as a beneficial effect, and allows designer to reduce the design base shear. However, literature shows that this idea cannot properly capture the SSI effects on nonlinear systems. ASCE 7-16 is the first edition of ASCE 7 that considers the SSI effect on yielding systems. This study investigates the consequences of practicing the new provisions on a wide range of buildings with different dynamic characteristics on different soil types. Ductility demand of the structure forms the performance metric of this study, and the probability that practicing SSI provisions, in lieu of fixed-base provisions, increases the ductility demand of the structure is computed. The analyses are conducted within a probabilistic framework which considers the uncertainties in the ground motion and in the properties of the soil-structure system. It is concluded that, for structures with surface foundation on moderate to soft soils, SSI regulations of both ASCE 7-10 and ASCE 7-16 are fairly likely to result in a similar and larger structural responses than those obtained by practicing the fixed-base design regulations. However, for squat and ordinary stiff structures on soft soil or structures with embedded foundation on moderate to soft soils, the SSI provisions of ASCE 7-16 result in performance levels that are closer to those obtained by practicing the fixed-base regulations. Finally, for structures on very soft soils, the new SSI provisions of ASCE 7-16 are likely to rather conservative designs.Comment: ASCE Structures Congress, Fort Worth, TX, USA, April 19-21 (2018

Effects of high-amylose maize starch and butyrylated high-amylose maize starch on azoxymethane-induced intestinal cancer in rats

Colorectal cancer (CRC) is a major cause of death worldwide. Studies suggest that dietary fibre offers protection perhaps by increasing colonic fermentative production of butyrate. This study examined the importance of butyrate by investigating the effects of resistant starch (RS) and butyrylated-RS on azoxymethane (AOM)-induced CRC in rats. Four groups (n = 30 per group) of Sprague–Dawley rats were fed AIN-93G-based diets containing a standard low-RS maize starch (LAMS), LAMS + 3% tributyrin (LAMST), 10% high-amylose maize starch (HAMS) and 10% butyrylated HAMS (HAMSB) for 4 weeks. Rats were injected once weekly for 2 weeks with 15 mg/kg AOM, maintained on diets for 25 weeks and then killed. Butyrate concentrations in large bowel digesta were higher in rats fed HAMSB than other groups (P < 0.001); levels were similar in HAMS, LAMS and LAMST groups. The proportion of rats developing tumours were lower in HAMS and HAMSB than LAMS (P < 0.05), and the number of tumours per rat were lower in HAMSB than LAMS (P < 0.05). Caecal digesta butyrate pools and concentrations were negatively correlated with tumour size (P < 0.05). Hepatic portal plasma butyrate concentrations were higher (P < 0.001) in the HAMSB compared with other groups and negatively correlated with tumour number per rat (P < 0.009) and total tumour size for each rat (P = 0.05). HAMSB results in higher luminal butyrate than RS alone or tributyrin. This is associated with reduced tumour incidence, number and size in this rat model of CRC supporting the important protective role of butyrate. Interventional strategies designed to maximize luminal butyrate may be of protective benefit in humans