Large amplitude vibration of thermo-electro-mechanically stressed FGM laminated plates

This paper presents a large amplitude vibration analysis of pre-stressed functionally graded material (FGM) laminated plates that are composed of a shear deformable functionally graded layer and two surface-mounted piezoelectric actuator layers. Nonlinear governing equations of motion are derived within the context of Reddy's higher-order shear deformation plate theory to account for transverse shear strain and rotary inertia. Due to the bending and stretching coupling effect, a nonlinear static problem is solved first to determine the initial stress state and pre-vibration deformations of the plate that is subjected to uniform temperature change, in-plane forces and applied actuator voltage. By adding an incremental dynamic state to the pre-vibration state, the differential equations that govern the nonlinear vibration behavior of pre-stressed FGM laminated plates are derived. A semi-analytical method that is based on one-dimensional differential quadrature and Galerkin technique is proposed to predict the large amplitude vibration behavior of the laminated rectangular plates with two opposite clamped edges. Linear vibration frequencies and nonlinear normalized frequencies are presented in both tabular and graphical forms, showing that the normalized frequency of the FGM laminated plate is very sensitive to vibration amplitude, out-of-plane boundary support, temperature change, in-plane compression and the side-to-thickness ratio. The CSCF and CFCF plates even change the inherent hard-spring characteristic to soft-spring behavior at large vibration amplitudes. (C) 2003 Elsevier B.V. All rights reserved.

Analysis of Piezoelectric sensor to detect flexural waves

The electromechanical transfer characteristics of adhesively bonded piezoelectric sensors are investigated. By the use of dynamic piezoelectricity theory, Mindlin plate theory for flexural wave propagation, and a multiple integral transform method, the frequency-response functions of piezoelectric sensors with and without backing materials are developed and the pressure-voltage transduction functions of the sensors calculated. The corresponding simulation results show that the sensitivity of the sensors is not only dependent on the sensors' inherent features, such as piezoelectric properties and geometry, but also on local characteristics of the tested structures and the admittance and impedance of the attached electrical circuit. It is also demonstrated that the simplified rigid mass sensor model can be used to analyze successfully the sensitivity of the sensor at low frequencies, but that the dynamic piezoelectric continuum model has to be used for higher frequencies, especially around the resonance frequency of the coupled sensor-structure vibration system.

Postbuckling of piezoelectric FGM plates subject to thermo-electro-mechanical loading

In this paper, we examine the postbuckling behavior of functionally graded material FGM rectangular plates that are integrated with surface-bonded piezoelectric actuators and are subjected to the combined action of uniform temperature change, in-plane forces, and constant applied actuator voltage. A Galerkin-differential quadrature iteration algorithm is proposed for solution of the non-linear partial differential governing equations. To account for the transverse shear strains, the Reddy higher-order shear deformation plate theory is employed. The bifurcation-type thermo-mechanical buckling of fully clamped plates, and the postbuckling behavior of plates with more general boundary conditions subject to various thermo-electro-mechanical loads, are discussed in detail. Parametric studies are also undertaken, and show the effects of applied actuator voltage, in-plane forces, volume fraction exponents, temperature change, and the character of boundary conditions on the buckling and postbuckling characteristics of the plates. (C) 2003 Elsevier Science Ltd. All rights reserved.

Analysis of the thermal stress behaviour of functionally graded hollow circular cylinders

This paper presents an analysis of the thermomechanical behavior of hollow circular cylinders of functionally graded material (FGM). The solutions are obtained by a novel limiting process that employs the solutions of homogeneous hollow circular cylinders, with no recourse to the basic theory or the equations of non-homogeneous thermoclasticity. Several numerical cases are studied, and conclusions are drawn regarding the general properties of thermal stresses in the FGM cylinder. We conclude that thermal stresses necessarily occur in the FGM cylinder, except in the trivial case of zero temperature. While heat resistance may be improved by sagaciously designing the material composition, careful attention must be paid to the fact that thermal stresses in the FGM cylinder are governed by more factors than are its homogeneous counterparts. The results that are presented here will serve as benchmarks for future related work. (C) 2003 Elsevier Science Ltd. All rights reserved.

Non-linear analysis of the thermo-electro-mechanical behaviour of shear deformable FGM plates with piezoelectric actuators

This paper investigates the non-linear bending behaviour of functionally graded plates that are bonded with piezoelectric actuator layers and subjected to transverse loads and a temperature gradient based on Reddy's higher-order shear deformation plate theory. The von Karman-type geometric non-linearity, piezoelectric and thermal effects are included in mathematical formulations. The temperature change is due to a steady-state heat conduction through the plate thickness. The material properties are assumed to be graded in the thickness direction according to a power-law distribution in terms of the volume fractions of the constituents. The plate is clamped at two opposite edges, while the remaining edges can be free, simply supported or clamped. Differential quadrature approximation in the X-axis is employed to convert the partial differential governing equations and the associated boundary conditions into a set of ordinary differential equations. By choosing the appropriate functions as the displacement and stress functions on each nodal line and then applying the Galerkin procedure, a system of non-linear algebraic equations is obtained, from which the non-linear bending response of the plate is determined through a Picard iteration scheme. Numerical results for zirconia/aluminium rectangular plates are given in dimensionless graphical form. The effects of the applied actuator voltage, the volume fraction exponent, the temperature gradient, as well as the characteristics of the boundary conditions are also studied in detail. Copyright (C) 2004 John Wiley Sons, Ltd.

The muscle strength and bone density relationship in young women: dependence on exercise status

Aim. Numerous studies report an association between muscle strength and bone mineral density (BMD) in young and older women. However, the participants are generally non-athletes, thus it is unclear if the relationship varies by exercise status. Therefore, the purpose was to examine the relationships between BMD and muscle strength in young women with markedly different exercise levels. Methods. Experimental design: cross-sectional. Setting: a University research laboratory. Participants: 18 collegiate gymnasts and 22 age- and weight-matched recreationally active control women. Measures: lumbar spine, femoral neck, arm, leg and whole body BMD (g/cm(2)) were assessed by dual X-ray absorptiometry. In addition, lumbar spine and femoral neck bone mineral apparent density (BMAD, g/cm(3)) was calculated. Handgrip strength and knee extensor and flexor torque (60degrees/s) were determined by dynamometry, and bench press and leg press strength (1-RM) using isotonic equipment. Results. BMD at all sites and bench press, leg press and knee flexor strength were greater in gymnasts than controls (p

Active and passive smoking and the risk of subarachnoid hemorrhage - An international population-based case-control study

Background and Purpose - This study was undertaken to better clarify the risks associated with cigarette smoking and subarachnoid hemorrhage (SAH). Methods - The study included 432 incident cases of SAH frequency matched to 473 community SAH-free controls to determine dose-dependent associations of active and passive smoking ( at home) and smoking cessation with SAH. Results - Compared with never smokers not exposed to passive smoking, the adjusted odds ratio for SAH among current smokers was 5.0 (95% confidence interval [CI], 3.1 to 8.1); for past smokers, 1.2 ( 95% CI, 0.8 to 2.0); and for passive smokers, 0.9 ( 95% CI, 0.6 to 1.5). Current and lifetime exposures showed a clear dose-dependent effect, and risks appeared more prominent in women and for aneurysmal SAH. Approximately 1 in 3 cases of SAH could be attributed to current smoking, but risks decline quickly after smoking cessation, even among heavy smokers. Conclusions - A strong positive association was found between cigarette smoking and SAH, especially for aneurysmal SAH and women, which is virtually eliminated within a few years of smoking cessation. Large opportunities exist for preventing SAH through smoking avoidance and cessation programs.

A Research Agenda for Assessing the Potential Contribution of Genomic Medicine to Tobacco Control

This paper identifies research priorities in evaluating the ways in which "genomic medicine"-the use of genetic information to prevent and treat disease-may reduce tobacco-related harm by: (1) assisting more smokers to quit; (2) preventing non-smokers from beginning to smoke tobacco; and (3) reducing the harm caused by tobacco smoking. The method proposed to achieve the first aim is pharmacogenetics", the use of genetic information to optimise the selection of smoking-cessation programmes by screening smokers for polymorphisms that predict responses to different methods of smoking cessation. This method competes with the development of more effective forms of smoking cessation that involve vaccinating smokers against the effects of nicotine and using new pharmaceuticals (such as cannabinoid antagonists and nicotine agonists). The second and third aims are more speculative. They include: screening the population for genetic susceptibility to nicotine dependence and intervening (eg, by vaccinating children and adolescents against the effects of nicotine) to prevent smoking uptake, and screening the population for genetic susceptibility to tobacco-related diseases. A framework is described for future research on these policy options. This includes: epidemiological modelling and economic evaluation to specify the conditions under which these strategies are cost-effective; and social psychological research into the effect of providing genetic information on smokers' preparedness to quit, and the general views of the public on tobacco smoking.

Advice on exercise from a family physician can help sedentary patients to become active

Objectives: To test the effectiveness, in the setting of primary health care, of verbal advice on exercise from a family physician (FP) combined with supporting written information. Design: A controlled trial with subjects allocated to a control group or one of two intervention groups using a balanced design based on day of the week. Setting: Ten general practices in Perth, Western Australia. Subjects: All sedentary patients consulting an FP. Intervention: Verbal advice on exercise from the FP and a pamphlet on exercise mailed to the patient's home address within 2 days of his/her visit to the doctor. Main outcome measure: Level of physical activity at followup. Results: 6,351 adult patients attending an FP practice completed a screening questionnaire, and 763 sedentary adults were recruited to the project. The response to follow-up, via a postal survey at 1, 6, and 12 months after the index consultation was 70%, 60%, and 57%, respectively. At 1 month a subsample of the control and intervention subjects were contacted for a telephone interview to verify self-reported levels of activity (n = 136). Treating all nonresponders as sedentary, at 1 month significantly more subjects in the combined intervention groups reported doing some physical activity (40%) compared with the control group (31%). Similarly, at 6 months, 30% of the control group and 38% of the combined intervention groups were now active. There was very little change at followup at 12 months (31% control and 36% intervention groups, respectively). Conclusion: A simple intervention aimed at the promotion of physical activity to sedentary patients in general practice can help reduce inactivity.

Active site-directed protein regulation

Regulation of protein function is vital for the control of cellular processes. Proteins are often regulated by allosteric mechanisms, in which effecters bind to regulatory sites distinct from the active sites and alter protein function. Intrasteric regulation, directed at the active site and thus the counterpart of allosteric control, is now emerging as an important regulatory mechanism.

Inactive free : total prostate specific antigen ratios in ejaculate from men with suspected and known prostate cancer, compared with young control men

Objective To measure free:total prostate specific antigen (PSA) ratios in ejaculate from men with suspected and known prostate cancer, and in young control men, to determine if this ratio might be useful in discriminating benign from malignant prostatic conditions. Patients, subjects and methods Forty-seven men with prostate cancer (positive biopsies), 52 men with suspected prostate cancer but who had negative biopsies and 28 young men (< 30 years old) and with no family history of cancer, provided either a single ejaculate specimen (total 59) or multiple specimens (total 193) on subsequent occasions. Free and total PSA were measured using appropriate assays. All specimens were diluted in a PSA-negative female serum pool. Results The median free:total PSA ratios were 0.76-0.81 among the patient groups and control men, and there was no statistical difference between the groups. These data presumably only reflect the inactive component of free PSA, given that any alpha(2)-macroglobulin or alpha(1)-antichymotrypsin in the assay serum diluent was likely to have bound the active free PSA component in these samples. Similar results were obtained from those providing single and multiple samples, suggesting that a single specimen is sufficient to reflect the seminal plasma free:total PSA ratio over that period. There was no relationship between seminal plasma free:total PSA ratio and age for the controls or the positive biopsy group, although there was a negative relationship (i.e. a decline with age) that almost reached significance in those with negative biopsies (P = 0.058, R-2 = 0.07). Conclusions This is the first report of free:total PSA ratios in the ejaculate of men with suspected and known prostate cancer compared with young control men. Although no significant changes were detected in the free:total PSA ratios in ejaculate, these results may be confounded by differences in ratios with age, as is the case for serum PSA or different molecular forms of PSA. Indeed, these data suggest that a large proportion of free PSA in seminal plasma may be inactive. Further studies are needed to determine the potential utility of measuring free:total PSA, or other candidate markers, in ejaculate to better discriminate benign from malignant prostate disease.

Constitutively Active Mutant D816VKit Induces Megakayocyte and Mast Cell Differentiation of Early Haemopoietic Cells from Murine Foetal Liver

Mutations of Kit at position D816 have been implicated in mastocytosis, acute myeloid leukaemia and germ cell tumours. Expression of this mutant Kit in cell lines results in factor-independent growth, differentiation and increased survival in vitro and tumourigenicity in vivo. Mutant D816VKit and wild-type Kit were expressed in murine primary haemopoietic cells and grown in stem cell factor (SCF) or the absence of factors. Expression of D816VKit did not lead to transformation as assessed by a colony assay, but resulted in enhanced differentiation of cells when compared to control cells. D816VKit induced an increase in the number of cells differentiating along the megakaryocyte lineage in the absence of factors. SCF had an added effect with an increase in differentiation of mast cells. Expression of wild-type Kit in the presence of SCF also failed to cause transformation and induced differentiation of mast cells and megakaryocytes. We conclude that constitutive expression of D816VKit in primary haemopoietic cells is not a sufficient transforming stimulus but leads to the survival and maturation of cells whose phenotype is influenced by the presence of SCF. (C) 2003 Elsevier Science Ltd. All rights reserved.

Evaluation of liquid Bacillus thuringiensis var. israelensis products for control of Australian Aedes arbovirus vectors

Laboratory bioassay studies were conducted in southeast Queensland, Australia,: on the efficacy of Teknar (R), VectoBac (R) 12AS, and Cybate (R) (active ingredient: 1,200 international toxic units Bacillus thuringiensis var, israelensis [Bti]) against 3rd instars of the arbovirus vectors Aedes aegypti. Ae. notoscriptus, Ae. vigilax, and Ae. camptorhynchus. Probit analyses were then used to determine LD,, (median lethal dose), LD95, and lethal dose ratios (LDR). Aedes aegypti and Ae. notoscriptus, both container-habitat species, tolerated the highest Bti concentrations compared with saltmarsh Ae. vigilax and Ae. camptorhynchus. For example, the LDR for Ae. vigilax versus Ae. notoscriptus exposed to Cybate was 0.14 (95% confidence limit [CL] 0.03-0.61). Similarly, the Cybate LDR for Ae. camptorhynchus versus Ae. notoscriptus was 0.22 (95% CL 0.07-0.70). Teknar produced similar results with an LDR of 0.21 (95% CL 0.04-1.10) for Aedes vigilax versus Aedes notoscriptus. Differences in product efficacy were found when tested against the 2 container-breeding species. Cybate was less effective than Teknar with LDRs of 1.55 (95% CL 0.65-3.67) and 1.87 (95% CL 0.68-5.15) for Aedes aegypti and Ae. notoscriptus, respectively. The significant differences in susceptibility between mosquito species and varying efficacy between products highlight the importance of evaluating concentration-response data prior to contracting with distributors of mosquito control products. This information is crucial to resistance management strategies.

Cost of malaria control in China: Henan's consolidation programme from community and government perspectives

Objective To assist with strategic planning for the eradication,of malaria in Henan Province, China, which reached the consolidation phase of malaria control in 1992, when only 318 malaria cases were reported, Methods We conducted a prospective two-year study of the costs for Henan's malaria control programme. We used a cost model that could also be applied to other malaria programmes in-mainland China, and analysed the cost of the three components of Henan's malaria programme. suspected malaria case management,, vector surveillance,,and population blood surveys. Primary cost data were collected from the government, and data on suspected malaria patient's were collected in two malaria counties (population 2 093 100). We enlisted the help of 260 village doctors. in six-townships or former communities (population 247 762), and studied all 12 315 reported cases of suspected malaria in catchment areas in 1994 and 1995. Findings The average-annual government investment in malaria control was estimated to be US$ 111 516 (case-management 59%; active blood surveys 25%;vector surveillance 12%; and contingencies and special projects 4%). The average cost (direct and indirect) for-patients seeking-treatment for suspected malaria was US$ 3.48, equivalent,to 10 days' income for rural residents. Each suspected malaria case cost the government an, average of US$ 0.78. Conclusion Further cuts in government funding will increase future costs, when epidemic malaria returns; investment in malaria control should therefore continue at least at current levels,of US$ 0.03 per person a risk.

Vibration instability in rolling mills: Modeling and experimental results

Models for the occurrence of the vibrational instability during rolling known as third octave chatter are presented and discussed. An analysis of rolling mill chatter was performed for the purpose of identifying characteristics of the vibrations and to determine any dependency on the rolling schedule. In particular, a stability criterion for the critical rolling speed is used to predict the maximum rolling speed without chatter instability on schedules from a 5 stand tandem mill rolling thin steel product. The results correlate well with measurements of critical speed occurring on the mill using a vibration monitor: This research provides significant insights into the chatter phenomena and has been used to investigate control methods for suppression of the instability.