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To characterise subjective symptoms in patients undergoing surgical repair of superior semicircular canal dehiscence.
Questionnaires assessing symptom severity and impact on function and quality of life were administered to patients before superior semicircular canal dehiscence surgery, between June 2011 and March 2016. Questionnaire sections included general quality of life, internal amplified sounds, dizziness and tinnitus, with scores of 0–100 points.
Twenty-three patients completed the questionnaire before surgery. Section scores (mean±standard deviation) were: 38.2 ± 25.2 for general quality of life, 52.5 ± 23.9 for internal amplified sounds, 35.1 ± 28.8 for dizziness, 33.3 ± 30.7 for tinnitus, and 39.8 ± 22.2 for the composite score. Cronbach's α statistic averaged 0.93 (range, 0.84–0.97) across section scores, and 0.83 for the composite score.
The Gopen–Yang Superior Semicircular Canal Dehiscence Questionnaire provides a holistic, patient-centred characterisation of superior semicircular canal dehiscence symptoms. Internal consistency analysis validated the questionnaire and provided a quantitative framework for further optimisation in the clinical setting.
The Parkes multibeam pulsar survey which began in 1997 and is now about 50% complete. It has discovered more than 400 new pulsars so far, including a number of young, high magnetic field, and relativistic binary pulsars. Early results, descriptions of the survey and follow up timing programs can be found in papers by Lyne et al. (1999 MNRAS in press), Camilo et al. (this volume), and Manchester et al. (this volume). This paper describes the data release policy and how you can gain access to the raw data and details on the pulsars discovered.
The Parkes multibeam pulsar survey uses a 13-element receiver operating at a wavelength of 20 cm to survey the inner Galactic plane with remarkable sensitivity. To date we have collected and analyzed data from 45% of the survey region (|b| < 5°; 260° < l < 50°), and have discovered 440 pulsars, in addition to re-detecting 190 previously known ones. Most of the newly discovered pulsars are at great distances, as inferred from a median dispersion measure (DM) of 400 cm−3 pc.
This is the first autopsy study in the United Kingdom to analyse the demographic and pathological characteristics of atheroma associated with sudden cardiac death in young people.
An observational retrospective study of referred cases of sudden cardiac death in the young (⩽35 years) associated with premature atheroma was carried out.
In total, 46 cases were referred, with a median age of 30 years (27, 32); 72% of the referred cases were male, with a mean body mass index of 30 kg/m2. Circumstances of death were as follows: at rest (n=21), exertion (n=7), in bed (n=7), related to drugs/alcohol (n=4), and unknown (n=7). A previous cardiac history was provided in 10 cases. A history of class A/B drug use was found in eight cases. There was macroscopic evidence of infarction in 10 cases (acute, n=3 and chronic, n=7). Microscopically, 10 cases demonstrated contraction band necrosis, 11 acute infarction, and 11 chronic infarction. Single-vessel disease predominated (n=28). The left anterior descending coronary artery was involved in 39/46 cases. Thrombosis was seen in 16 cases, mainly due to erosion; one case showed dual pathology with arrhythmogenic right ventricular cardiomyopathy and another showed left ventricular hypertrophy.
This study highlights premature atheroma mainly in a single vessel in young people with or without evidence of ischaemic damage in the ventricle. Dual pathology may occur. The role of arrhythmias and channelopathies are important considerations. Premature atheroma should prompt investigation for dyslipidaemias in family members.
Human campylobacteriosis exhibits a distinctive seasonality in temperate regions. This paper aims to identify the origins of this seasonality. Clinical isolates [typed by multi-locus sequence typing (MLST)] and epidemiological data were collected from Scotland. Young rural children were found to have an increased burden of disease in the late spring due to strains of non-chicken origin (e.g. ruminant and wild bird strains from environmental sources). In contrast the adult population had an extended summer peak associated with chicken strains. Travel abroad and UK mainland travel were associated with up to 17% and 18% of cases, respectively. International strains were associated with chicken, had a higher diversity than indigenous strains and a different spectrum of MLST types representative of these countries. Integrating empirical epidemiology and molecular subtyping can successfully elucidate the seasonal components of human campylobacteriosis. The findings will enable public health officials to focus strategies to reduce the disease burden.
Thin films of electroconductive poly[pyrrole-co-3−(1−pyrrolyl)propionic acid] were prepared by electropolymerization onto 3-aminopropyltrimethoxysilane modified and 3−(1−pyrrolyl)propionic acid derivatized interdigitated microsensor electrode (IME) arrays. The ω−(1−pyrrolyl) moiety on the surface of the device provides for specific adhesion of the polymer film to the device and the (N-pyrrolyl)propionic acid moiety on the polymer backbone provides for covalent attachment of bioactive molecules, such as biotin and urease, to the polymer surface. The immobilized, bioactive urease produces an ON/OFF conductimetric response traceable to analyte concentration.
Among different MEMS wafer level bonding processes glass frit bonding provides reliable vacuum tight seals in volume production. The quality of the seal is a function of both seal glass materials and the processing parameters used in glass frit bonding. Therefore, in this study Taguchi L18 screening Design of Experiment (DOE) was used to study the effect of materials and process variables on the quality of the glass seal in 6” silicon wafers bonded in EVG520IS bonder. Six bonding process variables at three levels and two types of sealing glass pastes were considered. The seals were characterized by Scanning Acoustic Microscopy (SAM), cross sectional Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Analysis (EDAX). The results were quantified into four responses for DOE analysis. Key results are a) peak temperature has the strongest influence on seal properties, b) hot melt paste has significantly lower defects compared to liquid paste, and c) peak firing temperatures can be as low as 400°C under certain conditions.
A process for forming thin (1-3 μm) stacks of Si/SiO2 or SiO2/Si/SiO2 layers into spherical shells 0.5-3.0 mm in diameter is demonstrated as the baseline for realizing sub-mm3 micro-robots. The fabrication process combines bulk and thin-film micromachining, design of novel masks, and multistage wet and dry etching to release the layers from the substrate. The released layers curl up, self assembling into a spherical shell. The radius of curvature of the released stack is a function of the type, thickness, and residual stresses in the layers. The diameter of the resulting shells is calculated using a mechanical model of the multi-layer stacks. This calculation is compared with measurements of fabricated spheres. The fabrication process is compatible with CMOS circuitry, and future work will focus on realizing spheres with embedded solar cell as a power source and a capacitor for energy storage, which will result in a functional micro-robot.
In this work, we report the post-growth investigation of the microstructure and stress in the AlN films grown on patterned amorphous dielectrics through micro-Raman spectroscopy. The surface texture of AlN/SiO2 structures was characterized by randomly oriented crystallites typical of polycrystalline films. Post growth analysis of the AlN/SiO2 structures using micro Raman spectroscopy did not reveal phonon modes corresponding to wurtzite AlN. The presence of randomly oriented crystallites with a possibility of oxidized Al phase in the AlN film could have suppressed the appearance of wurtzite AlN phonon peaks in the Raman spectrum. Profiling the stress and the microstructure of AlN/SiO2 structures across the width of the bridges is thus limited by these factors. AlN structures on SiO2 when subjected to wet etching in buffered HF (10:1) showed a clear change in texture. Micro-raman spectroscopy on the etched areas revealed wurtzite AlN like phonon modes. The appearance of wurtzite AlN modes can be attributed to the removal of oxidized Al phase in the AlN film after wet etching.
Progress in the state of the art of nanofabrication now allows devices that may enable the experimental sensing of bubble nucleation in nanochannels, and the direct measurement of the bubble nucleation rate in nanoconfined water and other fluids. In this paper we report on two aspects in achieving this goal: 1) new molecular dynamics simulations of nanobubble formation in nanoconfined argon and water model systems and 2) an ultrasensitive nanofluidic device architecture potentially able to detect individual nanobubble nucleation events.
Nanofluidic devices are finding growing interest for a variety of applications. An initial report is presented here on a wide range of parameters influencing transport of ionic species as they translocate across solid-state nanopores. AC electrical bias at low ionic concentration with overlapping electric double layers provides an enhancement of ionic flux over pure DC bias. Furthermore, results also indicate that concentration and pH gradients can be maintained across solid-state nanopores for extended periods of time that can last for several hours in the absence of driving forces such as electric fields.
As Microelectromechanical Systems (MEMS) continue to mature and increase in design complexity, the need to exploit rotation in MEMS devices has become more apparent. An in-plane piezoelectric rotational actuator is proposed that provides free deflections on the order of 1.5° with applied biases of less than 35V and nanoampere currents. Moments up to 6×10−8 N·m, corresponding to forces of 125 μN, were measured using MEMS cantilever springs. The actuator utilizes the low-power, high-force characteristics of lead zirconate titanate and a coupled, dual offset-beam design to provide efficient rotational displacement. The resulting power consumption is three orders of magnitude less than current electrothermal rotational designs.
In this work a novel technique to create nanometer sized air gaps for high frequency (HF) mechanical resonators will be presented. The technique is based on the narrowing of initially wide gaps with a conformal “narrowing” layer. The novelty of this technique is that it enables the creation of narrow high-aspect ratio gaps (e.g. 100nm gaps in 10μm thick layers) without the need for complex lithography or high aspect ratio etching. Furthermore, the electrodes and the resonator itself can be patterned in a single processing step. The process methodology will be explained and validation experiments in a silicon-germanium (SiGe) based technology will be shown. This technology uses low temperature (∼450°C) poly silicon-germanium (SiGe) as the structural layer, which can be processed above CMOS, and therefore allows the fabrication of MEM devices above CMOS.
Wrinkling of thin sheets under strain is a universal phenomenon. The amplitude and period of the wrinkles formed in a thin sheet clamped at both ends are dependent on its strain and material parameters. In our study, wrinkling is observed in microscale for double clamped thin films (L>W>>t) consisting of 200nm deposited low stress silicon nitride bridges fabricated by bulk micromachining. A bilayer system is formed with 30nm aluminum evaporated on to these bridges. At room temperature the bridges are essentially flat. When an electrical current passes through the aluminum layer electrothermal, heating results in thermal expansion that wrinkles the bilayer. In addition we investigated various dimensions of the bridges and their correlation to the amplitude and the number of wrinkles. The observations are compared to existing wrinkling theory.
In this paper, we report the results of a rapid and room temperature integration approach for the selective and structured deposition of carbon nanotubes (CNTs) into three-dimensional microstructures. The approach exploits electrophoretic deposition (EPD) from an aqueous suspension of CNTs, together with suitably patterned and electrically-energized microstructure-bearing substrates. Uniform 2-D and 3-D micropatterns of CNTs on wafer scale have been achieved in less than 4 minutes with controllable thicknesses ranging from 133nm to several micrometers. Orientation of the deposited CNTs was observed in microstructures with certain dimensions. Surface hydrophobicity of the microstructures was found to be critical in achieving well-defined micropatterning of CNTs. A hydrophobic microstructure surface leads to the selective patterning profiles of CNTs, while a hydrophilic surface induces CNTs assembly over the entire microstructure, with resultant loss of selectivity. This approach can be further extended to fabricate 3-D micropatterns with multilayer materials on flexible substrate through the aid of transfer micromolding techniques.
The results of micromechanical tensile experiments performed on thin aluminum samples are presented and discussed. The micro tensile test system and the design of the samples, based on finite element modeling (FEM), and their production by micromachining are briefly described. Some examples of the stress strain curves are presented. The Young's modulus and critical parameters (flow and rupture stress and strains) are reported. The micro structural changes induced by the tensile experiment were observed during and after the testing by scanning electron microscopy (SEM) and transmission electron microscopy (TEM).The results of micromechanical tensile experiments performed on thin aluminum samples are presented and discussed. The micro tensile test system and the design of the samples, based on finite element modeling (FEM), and their production by micromachining are briefly described. Some examples of the stress strain curves are presented. The Young's modulus and critical parameters (flow and rupture stress and strains) are reported. The micro structural changes induced by the tensile experiment were observed during and after the testing by scanning electron microscopy (SEM) and transmission electron microscopy (TEM).
Minimizing risk is an important factor in new product planning because high volume breakthrough products require tens of millions of dollars to develop and bring to market. Sometimes risk can be minimized by following the IC model: build new devices on an existing process – just change the mask set. This approach obviously has limits. Adoption of new materials and processes greatly expands the horizon for “disruptive” products. This paper uses a case study approach to examine how changes in masks, materials and unit processes were used, and will continue to be used, to produce MEMS products for high volume applications.
The emergence of BioMEMS fabrication technologies such as soft lithography, micromolding and assembly of 3D structures, and biodegradable microfluidics, are already making significant contributions to the field of regenerative medicine. Over the past decade, BioMEMS have evolved from early silicon laboratory devices to polymer-based structures and even biodegradable constructs suitable for a range of ex vivo and in vivo applications. These systems are still in the early stages of development, but the long-term potential of the technology promises to enable breakthroughs in health care challenges ranging from the systemic toxicity of drugs to the organ shortage. Ex vivo systems for organ assist applications are emerging for the liver, kidney and lung, and the precision and scalability of BioMEMS fabrication techniques offer the promise of dramatic improvements in device performance and patient outcomes.
Ultimately, the greatest benefit from BioMEMS technologies will be realized in applications for implantable devices and systems. Principal advantages include the extreme levels of achievable miniaturization, integration of multiple functions such as delivery, sensing and closed loop control, and the ability of precision microscale and nanoscale features to reproduce the cellular microenvironment to sustain long-term functionality of engineered tissues. Drug delivery systems based on BioMEMS technologies are enabling local, programmable control over drug concentrations and pharmacokinetics for a broad spectrum of conditions and target organs. BioMEMS fabrication methods are also being applied to the development of engineered tissues for applications such as wound healing, microvascular networks and bioartificial organs. Here we review recent progress in BioMEMS-based drug delivery systems, engineered tissue constructs and organ assist devices for a range of ex vivo and in vivo applications in regenerative medicine.
Liquid metal microscale switches, often using mercury, are sometimes used in place of solid-solid contact switches because of the ability to minimize damage from switching and the ability to make good contacts for electrical and thermal conductivity. However, mercury has potential health and safety problems, and is difficult to use at high frequency (kHz) operation due to poor adhesion between the liquid-solid contacts. One alternative to the mechanical and chemical problems of a liquid mercury switch is using soft metals, such as gallium or tin, as a solid metal sphere for switches that can melt at moderate temperatures. Ga micro-spheres for switching operations were deposited on a substrate consisting of photolithographically patterned W films on SiO2 and Si substrates by electroplating, and the applicability for use in a microscale switch was investigated by characterizing the macro structure, hardness, and electrical performance during switching. The resistivity of the electroplated Ga droplets was similar to the theoretical value for pure Ga, and suggests that the electrodeposited Ga will be suitable for a solid MEMS switch. The hardness of the Ga sphere was 5.7 MPa. This suggests a maximum of ∼40 micron-Newton can be applied to each 50 micron-meter radius Ga contact in the current configuration for switching applications. When the Ga spheres were investigated for electrical performance during hot switching, the resistance increased over six switching cycles, but the original lower resistivity was recovered after a 393 K thermal reflow process.
Fatigue properties of thin film materials are extremely important to design durable and reliable microelectromechanical systems (MEMS) devices. However, it is rather difficult to apply conventional fatigue testing method of bulk materials to thin films. Therefore, a fatigue testing method fitted to thin film materials is required. In this investigation, we have developed a fatigue testing method that uses a resonance of cantilever type specimen prepared from thin films. Cantilever beam specimens with dimensions of 1(W) × 3(L) × 0.01(t) mm3 were prepared from Ni-P amorphous alloy thin films and gold foils. In addition, cantilever beam specimens with dimension of 3(L) × 0.3(W) × 0.005(t) mm3 were also prepared from single crystalline silicon thin films. These specimens were fixed to a holder that is connected to an golddio speaker used as an actuator, and were resonated in bending mode. In order to check the validity of this testing method, Young's moduli of these specimens were measured from resonant frequencies. The average Young's modulus of Ni-P was 108 GPa and that of gold foil specimen was 63 GPa, and these values were comparable with those measured by other techniques. This indicates that the resonance occurred theoretically-predicted manner and this testing method is valid for measuring the fatigue properties of thin films. Resonant fatigue tests were carried out for these specimens by changing amplitude range of resonance, and S-N curves were successfully obtained.