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Biomedical subjects

G Hayward

Publications and source records attributed to G Hayward.

At least 19 recordsLinked to original sources
PubMed2001

Seroepidemiology and molecular epidemiology of Kaposi's sarcoma-associated herpesvirus among Jewish population groups in Israel.

BACKGROUND: The incidence of classic Kaposi's sarcoma among Jews in Israel is among the highest in the developed world. Kaposi's sarcoma-associated herpesvirus (KSHV or human herpesvirus 8) is causally linked to Kaposi's sarcoma. Very little is known about the prevalence of KSHV in the Middle East or about the modes of transmission in Mediterranean countries. METHODS: From 1992 through 1995, sera were obtained from 1648 adults who had tested positive for hepatitis B virus (HBV) surface antigen 20 years earlier at blood donations; sera were also obtained from 2403 of their family members. All sera were tested for anti-KSHV antibodies with the use of an indirect immunofluorescence assay. To analyze the effects of various factors on the risk of KSHV infection for both the HBV-positive cohort and their families, logistic regression for cluster data and generalized estimating equations were used. All statistical tests were two-sided. RESULTS: Among family members, the seroprevalence of antibodies against KSHV was 9.9% (95% confidence interval [CI] = 8.7% to 11.1%); among the former blood donors who had tested positive for hepatitis B, it was 22% (95% CI = 19.9% to 24.1%). Overall, the best predictor of KSHV status was the place of birth. The most important risk factors found for both husband and wife to test KSHV positive were their own places of birth and their spouse's seropositivity. For a child to test positive, the most important risk factor was maternal seropositivity. CONCLUSIONS: The crude prevalence rate of KSHV among the Jewish population in Israel is 9.9%. Important routes of KSHV transmission in the families studied are spouse to spouse and mother to child. The presence of KSHV in Jews in Israel of all ethnic origins and their high incidence of reported Kaposi's sarcoma suggest that KSHV was introduced into the Jewish population prior to the major Diaspora.

Adolescent↗
PubMed2001

Micromachining of a piezocomposite transducer using a copper vapor laser.

A 1-3 piezocomposite transducer with front face dimensions of 2 x 2 mm has been micromachined using a copper vapor laser. The device consists of PZT5A piezoceramic pillars with a 65-micron pitch suspended in a low viscosity thermosetting polymer. The kerf width is 13 microns, and the transducer thickness is 170 microns, making the device suitable for ultrasonic reception at frequencies close to 10 MHz.

Journal Article↗
PubMed2001

The generation and detection of longitudinal guided waves in thin fibers using a conical transformer.

This paper describes a technique to couple ultrasonic energy from a piezoceramic disc transducer into a fiber waveguide to induce longitudinal propagation. A polymer cone is utilized to bond the fiber waveguide onto the surface of the disc and to behave as a mechanical transformer, converting lateral displacements at its base into longitudinal displacements at its apex. Wideband finite element analysis (FEA) results are provided to show that the bond efficiently couples the radial modes of a disc transducer into fiber waveguides for longitudinal mode excitation. Furthermore, narrowband FEA is utilized to investigate how the geometry and material properties of the bond and waveguide influence the coupling efficiency. The technique is then quantified in terms of signal-to-coherent noise ratio (SCNR), reflecting its ability to generate the desired longitudinal waveguide mode and reject erroneous modes. Finally, design parameters are outlined for the successful implementation of this technique.

Journal Article↗
PubMed2001

Localisation of the subthalamic nucleus using Radionics Image Fusion and Stereoplan combined with field potential recording. A technical note.

Subthalamic nucleus stimulation is an effective therapy for alleviating parkinsonian tremor, rigidity and bradykinesia. Although microelectrode recording is said to be essential for accurate targeting, this often prolongs the operation and the multiple recording tracts required may increase the incidence of complications, particularly haemorrhage. We describe a technique for implantation of deep brain electrodes in the subthalamic nucleus using MRI/CT fusion for anatomical localisation followed by bipolar recording of focal field potentials via the implanted stimulating electrode for neurophysiological confirmation of the stimulation site. The technique is effective, safe and requires much less time, and can be used as an alternative method to microelectrode recording.

Electric Stimulation Therapy↗
PubMed2000

Wave propagation in 0-3/3-3 connectivity composites with complex microstructure.

This work presents a study of the properties of particulate composites. The whole range of particle volume fraction (0-1) and ideal 0-3, 3-3 and intermediate 0-3/3-3 connectivities are analysed. Two different approaches to produce a realistic model of the complex microstructure of the composites are considered. The first one is based on a random location of mono-dispersed particles in the matrix; while the second incorporates a size distribution of the particles based on experimental measurements. Different particle shapes are also considered. A commercial finite element package was used to study the propagation of acoustic plane waves through the composite materials. Due to the complexity of the problem, and as a first step, a two-dimensional model was adopted. The results obtained for the velocity of sound propagation from the finite element technique are compared with those from other theoretical approaches and with experimental data. The study validates the use of this technique to model acoustic wave propagation in 0-3/3-3 connectivity composites. In addition, the finite element calculations, along with the detailed description of the microstructure of the composite, provide valuable information about the micromechanics of the sample and the influence of the microstructure on macroscopic properties.

Acoustics↗
PubMed2000

Beam profile measurements and simulations for ultrasonic transducers operating in air

This paper outlines a method that has been implemented to predict and measure the acoustic radiation generated by ultrasonic transducers operating into air in continuous wave mode. Commencing with both arbitrary surface displacement data and radiating aperture, the transmitted pressure beam profile is obtained and includes simulation of propagation channel attenuation and where necessary, the directional response of any ultrasonic receiver. The surface displacement data may be derived directly, from laser measurement of the vibrating surface, or indirectly, from finite element modeling of the transducer configuration. To validate the approach and to provide experimental measurement of transducer beam profiles, a vibration-free, draft-proof scanning system that has been installed within an environmentally controlled laboratory is described. A comparison of experimental and simulated results for piezoelectric composite, piezoelectric polymer, and electrostatic transducers is then presented to demonstrate some quite different airborne ultrasonic beam-profile characteristics. Good agreement between theory and experiment is obtained. The results are compared with those expected from a classical aperture diffraction approach and the reasons for any significant differences are explained.

Journal Article↗
PubMed2000

Domestic and personal accidents. Prevention in the absence of professional supervision.

This paper provides a review of a selection of recent papers, most of which derive from presentations given at the 4th World Conference on Injury Prevention and Control or the 6th International Conference on Product Safety Research, both of which took place in Amsterdam in May 1998. What all the accidents studied in these papers have in common is the absence of professional supervision. Everyone immediately involved in the incident--whether as injured party, unintended cause or informal supervisor is an 'amateur'. It is proposed that the term 'domestic and personal accidents' should be used to describe this group of accidents, the study of which has been neglected in comparison to transport and occupational injuries. It is argued that domestic and personal activities are more heterogeneous than ones with an element of professional supervision and are therefore more difficult to prevent. Nevertheless examples are given of where 'horizontal' approaches to analysis and prevention of these accidents have proved possible.

Accidents, Home↗
PubMed1996

Risk of injury per hour of exposure to consumer products.

The aim of this study was to determine and compare the risk of injury per hour of use for a range of consumer products. Exposure data was derived from interviewing a large sample of adults about their use of 76 common kitchen, do-it-yourself and household products. This was combined with hospital sample data for injuries involving each product, to yield the risk-of-injury-per-hour-of-use. Powered cutting equipment, access equipment (ladders and scaffolding) and products with sharp blades were shown to have a comparatively high risk, along with cycles, sunbeds, creosote, cement, car jacks and exercise weights. Perceived risk was shown to be a poor basis for priority setting, but a practical guide to priority for preventive action can be provided by "mapping" products on a plot of the risk of injury per hour of use vs the total medical costs of such accidents.

Accident Prevention↗
PubMed1993

The human cytomegalovirus 86K immediate early (IE) 2 protein requires the basic region of the TATA-box binding protein (TBP) for binding, and interacts with TBP and transcription factor TFIIB via regions of IE2 required for transcriptional regulation.

The 86K immediate early (IE) 2 protein of human cytomegalovirus trans-activates a number of homologous and heterologous promoters, including the cellular promoter for the 70K heat-shock protein (hsp70), and the human immunodeficiency virus long terminal repeat. We have previously shown that IE2 trans-activates these two promoters in a TATA-dependent manner, and that IE2 is able to form a direct contact with TATA-box binding protein (TBP) in vitro. We now show that IE2 binds to the basic repeat region of TBP. In addition IE2 can contact a second general transcription factor, TFIIB. We have mapped the TBP- and TFIIB-binding regions within IE2 and show that these regions overlap, and also lie within parts of the protein previously identified as being required for the trans-activation and autoregulation functions of IE2.

Base Sequence↗