Search

AIMS: To systematic review and meta-analyse the association and mechanistic links between atrial fibrillation (AF) and cognitive impairment. METHODS AND RESULTS: PubMed, EMBASE, and Cochrane Library were searched up to 27 March 2021 and yielded 4534 citations. After exclusions, 61 were analysed; 15 and 6 studies reported on the association of AF and cognitive impairment in the general population and post-stroke cohorts, respectively. Thirty-six studies reported on the neuro-pathological changes in patients with AF; of those, 13 reported on silent cerebral infarction (SCI) and 11 reported on cerebral microbleeds (CMB). Atrial fibrillation was associated with 39% increased risk of cognitive impairment in the general population [n = 15: 2 822 974 patients; hazard ratio = 1.39; 95% confidence interval (CI) 1.25-1.53, I2 = 90.3%; follow-up 3.8-25 years]. In the post-stroke cohort, AF was associated with a 2.70-fold increased risk of cognitive impairment [adjusted odds ratio (OR) 2.70; 95% CI 1.66-3.74, I2 = 0.0%; follow-up 0.25-3.78 years]. Atrial fibrillation was associated with cerebral small vessel disease, such as white matter hyperintensities and CMB (n = 8: 3698 patients; OR = 1.38; 95% CI 1.11-1.73, I2 = 0.0%), SCI (n = 13: 6188 patients; OR = 2.11; 95% CI 1.58-2.64, I2 = 0%), and decreased cerebral perfusion and cerebral volume even in the absence of clinical stroke. CONCLUSION: Atrial fibrillation is associated with increased risk of cognitive impairment. The association with cerebral small vessel disease and cerebral atrophy secondary to cardioembolism and cerebral hypoperfusion may suggest a plausible link in the absence of clinical stroke. PROSPERO CRD42018109185.

Research links high blood pressure variability (BPV) with stroke and cerebrovascular disease, however, its association with cognition remains unclear. Moreover, it remains uncertain which BP-derived parameter (ie, variability or mean) holds more significance in understanding vascular contributions to cognitive impairment. We searched PubMed, Embase, PsycINFO, and Scopus and performed a meta-analysis of studies that quantified the association between resting BPV with dementia or cognitive impairment in adults. Two authors independently reviewed all titles, abstracts, and full-texts and extracted data, following Preferred Reporting Items for Systematic Reviews and Meta-Analyses and Meta-Analysis of Observational Studies in Epidemiology guidelines. Study quality was assessed using the (modified) Newcastle-Ottawa Scale. A multilevel meta-analysis was used, which included effect sizes for both BPV and mean BP, with a combined end point of dementia or cognitive impairment as primary outcome. In the primary analysis, 54 effect sizes were extracted from 20 studies, with a total analytical sample of n=7 899 697. Higher systolic BPV (odds ratio [OR], 1.25 [95% CI, 1.16-1.35]), mean systolic pressure (OR, 1.12 [95% CI, 1.02-1.29]), diastolic BPV (OR, 1.20 [95% CI, 1.12-1.29]), and mean diastolic pressure (OR, 1.16 [95% CI, 1.04-1.29]) were associated with dementia and cognitive impairment. A direct comparison showed that mean BP effect sizes were less strong than BPV effect sizes (OR, 0.92 [95% CI, 0.87-0.97], P<0.01), indicating that the relative contribution of BPV exceeded that of mean BP. Methodological and statistical heterogeneity was high. Secondary analyses were less consistent as to whether BPV and mean BP were differentially associated with dementia subtypes and cognitive domains. Future studies are required to investigate BPV as a target for dementia prevention.

Contains fulltext : 243916.pdf (Publisher’s version ) (Open Access)

Contains fulltext : 243916.pdf (Publisher’s version ) (Open Access)

Contains fulltext : 243916.pdf (Publisher’s version ) (Open Access)

Background: Research links blood pressure variability (BPV) with stroke; however, the association with cerebral small-vessel disease (CSVD) remains unclear. As BPV and mean blood pressure are interrelated, it remains uncertain whether BPV adds additional information to understanding cerebrovascular morphological characteristics. Methods and Results: A systematic review was performed from inception until March 3, 2019. Eligibility criteria included population, adults without stroke (<4 weeks); exposure, BPV quantified by any metric over any duration; comparison, (1) low versus high or mean BPV and (2) people with versus without CSVD; and outcomes, (1) CSVD as subcortical infarct, lacunae, white matter hyperintensities, cerebral microbleeds, or enlarged perivascular spaces; and (2) standardized mean difference in BPV. A total of 27 articles were meta-analyzed, comprising 12 309 unique brain scans. A total of 31 odds ratios (ORs) were pooled, indicating that higher systolic BPV was associated with higher odds for CSVD (OR, 1.27; 95% CI, 1.14–1.42; I2=85%) independent of mean systolic pressure. Likewise, higher diastolic BPV was associated with higher odds for CSVD (OR, 1.30; 95% CI, 1.14–1.48; I2=53%) independent of mean diastolic pressure. There was no evidence of a pairwise interaction between systolic/diastolic and BPV/mean ORs (P=0.47), nor a difference between BPV versus mean pressure ORs (P=0.58). Fifty-four standardized mean differences were pooled and provided similar results for pairwise interaction (P=0.38) and difference between standardized mean differences (P=0.70). Conclusions: On the basis of the available studies, BPV was associated with CSVD independent of mean blood pressure. However, more high-quality longitudinal data are required to elucidate whether BPV contributes unique variance to CSVD morphological characteristics.

The COVID-19 pandemic poses a significant stress on health resources in Australia. The Heart Rhythm Council of the Cardiac Society of Australia and New Zealand aims to provide a framework for efficient resource utilisation balanced with competing risks when appropriately treating patients with cardiac arrhythmias. This document provides practical recommendations for the electrophysiology (EP) and cardiac implantable electronic devices (CIED) services in Australia. The document will be updated regularly as new evidence and knowledge is gained with time.Copyright © 2020

The COVID-19 pandemic poses a significant stress on health resources in Australia. The Heart Rhythm Council of the Cardiac Society of Australia and New Zealand aims to provide a framework for efficient resource utilisation balanced with competing risks when appropriately treating patients with cardiac arrhythmias. This document provides practical recommendations for the electrophysiology (EP) and cardiac implantable electronic devices (CIED) services in Australia. The document will be updated regularly as new evidence and knowledge is gained with time.Copyright © 2020

The COVID-19 pandemic poses a significant stress on health resources in Australia. The Heart Rhythm Council of the Cardiac Society of Australia and New Zealand aims to provide a framework for efficient resource utilisation balanced with competing risks when appropriately treating patients with cardiac arrhythmias. This document provides practical recommendations for the electrophysiology (EP) and cardiac implantable electronic devices (CIED) services in Australia. The document will be updated regularly as new evidence and knowledge is gained with time.

Background: A body of empirical work demonstrates that wide fluctuations in a person's blood pressure across consecutive measures, known as blood pressure variability (BPV), hold prognostic value to predict stroke and transient ischemic attack. However, the magnitude of association between BPV and other neurological outcomes remains less clear. This systematic review aims to pool together data regarding BPV with respect to incident dementia, cognitive impairment, and cognitive function. Methods: Electronic databases (MEDLINE, EMBASE, and SCOPUS) will be searched for the key words blood pressure variability and outcomes of dementia, cognitive impairment, and cognitive function. Authors and reference lists of included studies will also be contacted to identify additional published and unpublished studies. Eligibility criteria are as follows: population - adult humans (over 18 years but with no upper age limit) without dementia at baseline, with or without elevated blood pressure, or from hypertensive populations (systolic blood pressure ≥ 140 mmHg and/or diastolic blood pressure ≥ 90 mmHg or use of antihypertensive drug for hypertension) and from primary care, community cohort, electronic database registry, or randomized controlled trial (RCT); exposure - any metric of BPV (systolic, diastolic or both) over any duration; comparison - persons without dementia who do not have elevated BPV; and outcome - dementia, cognitive impairment, cognitive function at follow-up from standardized neurological assessment, or cognitive testing. Article screening will be undertaken by two independent reviewers with disagreements resolved through discussion. Data extraction will include original data specified as hazard ratios, odds ratios, correlations, regression coefficients, and original cell data if available. Risk of bias assessment will be undertaken by two independent reviewers. Meta-analytic methods will be used to synthesize the data collected relating to the neurological outc

The fall of the Annama meteorite occurred early morning (local time) on April 19, 2014 on the Kola Peninsula (Russia). Based on mineralogy and physical properties, Annama is a typical H chondrite. It has a high Ar-Ar age of 4.4 Ga. Its cosmic ray exposure history is atypical as it is not part of the large group of H chondrites with a prominent 7–8 Ma peak in the exposure age histograms. Instead, its exposure age is within uncertainty of a smaller peak at 30 ± 4 Ma. The results from short-lived radionuclides are compatible with an atmospheric pre-entry radius of 30–40 cm. However, based on noble gas and cosmogenic radionuclide data, Annama must have been part of a larger body (radius >65 cm) for a large part of its cosmic ray exposure history. The 10Be concentration indicates a recent (3–5 Ma) breakup which may be responsible for the Annama parent body size reduction to 30–35 cm pre-entry radius. © The Meteoritical Society, 2017.

Summary There is a growing literature on the relationship between team processes and clinical performance. The purpose of this review is to summarize these articles and examine the impact of team process behaviours on clinical performance. We conducted a literature search in five major databases. Inclusion criteria were: English peer-reviewed papers published between January 2001 and May 2012, which showed or tried to show (i) a statistical relationship of a team process variable and clinical performance or (ii) an improvement of a performance variable through a team process intervention. Study quality was assessed using predefined quality indicators. For every study, we calculated the relevant effect sizes. We included 28 studies in the review, seven of which were intervention studies. Every study reported at least one significant relationship between team processes or an intervention and performance. Also, some non-significant effects were reported. Most of the reported effect sizes were large or medium. The study quality ranged from medium to high. The studies are highly diverse regarding the specific team process behaviours investigated and also regarding the methods used. However, they suggest that team process behaviours do influence clinical performance and that training results in increased performance. Future research should rely on existing theoretical frameworks, valid, and reliable methods to assess processes such as teamwork or coordination and focus on the development of adequate tools to assess process performance, linking them with outcomes in the clinical setting

Although previously considered entirely reversible, general anaesthesia is now being viewed as a potentially significant risk to cognitive performance at both extremes of age. A large body of preclinical as well as some retrospective clinical evidence suggest that exposure to general anaesthesia could be detrimental to cognitive development in young subjects, and might also contribute to accelerated cognitive decline in the elderly. A group of experts in anaesthetic neuropharmacology and neurotoxicity convened in Salzburg, Austria for the BJA Salzburg Seminar on Anaesthetic Neurotoxicity and Neuroplasticity. This focused workshop was sponsored by the British Journal of Anaesthesia to review and critically assess currently available evidence from animal and human studies, and to consider the direction of future research. It was concluded that mounting evidence from preclinical studies reveals general anaesthetics to be powerful modulators of neuronal development and function, which could contribute to detrimental behavioural outcomes. However, definitive clinical data remain elusive. Since general anaesthesia often cannot be avoided regardless of patient age, it is important to understand the complex mechanisms and effects involved in anaesthesia-induced neurotoxicity, and to develop strategies for avoiding or limiting potential brain injury through evidence-based approaches

Network Verification is emerging as a critical enabler to manage large complex networks. In order to scale to data-center networks found in Microsoft Azure we developed a new data structure called ddNF, disjoint difference Normal Form, that serves as an efficient container for a small set of equivalence classes over header spaces. Our experiments show that ddNFs outperform representations proposed in previous work, in particular representations based on BDDs, and is especially suited for incremental verification. The advantage is observed empirically; in the worst case ddNFs are exponentially inferior than using BDDs to represent equivalence classes. We analyze main characteristics of ddNFs to explain the advantages we are observing.

Background - Although adiposity is increasingly recognized as a risk factor for atrial fibrillation (AF), the importance of epicardial fat compared with other adipose tissue depots remains uncertain. We sought to characterize and compare the associations of AF with epicardial fat and measures of abdominal and overall adiposity. Methods and Results - We conducted a meta-analysis of 63 observational studies including 352 275 individuals, comparing AF risk for 1-SD increases in epicardial fat, waist circumference, waist/hip ratio, and body mass index. A 1-SD higher epicardial fat volume was associated with a 2.6-fold higher odds of AF (odds ratio, 2.61; 95% confidence interval [CI], 1.89-3.60), 2.1-fold higher odds of paroxysmal AF (odds ratio, 2.14; 95% CI, 1.45-3.16) and, 5.4-fold higher odds of persistent AF (odds ratio, 5.43; 95% CI, 3.24-9.12) compared with sinus rhythm. Likewise, a 1-SD higher epicardial fat volume was associated with 2.2-fold higher odds of persistent compared with paroxysmal AF (odds ratio, 2.19; 95% CI, 1.66-2.88). Similar associations existed for postablation, postoperative, and postcardioversion AF. In contrast, associations of abdominal and overall adiposity with AF were less extreme, with relative risks per 1-SD higher values of 1.32 (95% CI, 1.25-1.41) for waist circumference, 1.11 (95% CI, 1.08-1.14) for waist/hip ratio, and 1.22 (95% CI, 1.17-1.27) for body mass index. Conclusions - Strong and graded associations were observed between increasing epicardial fat and AF. Moreover, the strength of associations of AF with epicardial fat is greater than for measures of abdominal or overall adiposity. Further studies are needed to assess the mechanisms and clinical relevance of epicardial fat.Copyright © 2016 American Heart Association, Inc.

Background - Although adiposity is increasingly recognized as a risk factor for atrial fibrillation (AF), the importance of epicardial fat compared with other adipose tissue depots remains uncertain. We sought to characterize and compare the associations of AF with epicardial fat and measures of abdominal and overall adiposity. Methods and Results - We conducted a meta-analysis of 63 observational studies including 352 275 individuals, comparing AF risk for 1-SD increases in epicardial fat, waist circumference, waist/hip ratio, and body mass index. A 1-SD higher epicardial fat volume was associated with a 2.6-fold higher odds of AF (odds ratio, 2.61; 95% confidence interval [CI], 1.89-3.60), 2.1-fold higher odds of paroxysmal AF (odds ratio, 2.14; 95% CI, 1.45-3.16) and, 5.4-fold higher odds of persistent AF (odds ratio, 5.43; 95% CI, 3.24-9.12) compared with sinus rhythm. Likewise, a 1-SD higher epicardial fat volume was associated with 2.2-fold higher odds of persistent compared with paroxysmal AF (odds ratio, 2.19; 95% CI, 1.66-2.88). Similar associations existed for postablation, postoperative, and postcardioversion AF. In contrast, associations of abdominal and overall adiposity with AF were less extreme, with relative risks per 1-SD higher values of 1.32 (95% CI, 1.25-1.41) for waist circumference, 1.11 (95% CI, 1.08-1.14) for waist/hip ratio, and 1.22 (95% CI, 1.17-1.27) for body mass index. Conclusions - Strong and graded associations were observed between increasing epicardial fat and AF. Moreover, the strength of associations of AF with epicardial fat is greater than for measures of abdominal or overall adiposity. Further studies are needed to assess the mechanisms and clinical relevance of epicardial fat.Copyright © 2016 American Heart Association, Inc.

Network Verification is emerging as a critical enabler to manage large complex networks. In order to scale to data-center networks found in Microsoft Azure we developed a new data structure called ddNF, disjoint difference Normal Form, that serves as an efficient container for a small set of equivalence classes over header spaces. Our experiments show that ddNFs outperform representations proposed in previous work, in particular representations based on BDDs, and is especially suited for incremental verification. The advantage is observed empirically; in the worst case ddNFs are exponentially inferior than using BDDs to represent equivalence classes. We analyze main characteristics of ddNFs to explain the advantages we are observing.

Batch adsorption experiments were carried out for the removal of dye congo red (CR) from aqueous solutions using bagasse charcoal (BC) and banana peels (BP). Experiments were carried out as a function of contact time, initial dye concentration, adsorbent dose and ionic strength. The results showed that the amount of dye adsorbed increased with increasing initial dye concentration and contact time. The kinetics of basic dye adsorption nicely followed the pseudo second-order rate expression and demonstrates that intraparticle diffusion plays a significant role in the adsorption process. The adsorption data fitted well with Langmuir, Freundlich, Temkin, Dubinin and Radushkevich and Generalized isotherms. The characteristic parameters for each model have been determined. The Langmuir isotherm gave the best correlation for the adsorption of dye congo red on both the adsorbents. The monolayer saturation capacity was found to be 45.3 and 44.4 mg/g for BC and BP respectively. The value of separation factor (RL) insinuates that BC and BP can be used as effective adsorbents. The results of the present study corroborate that BC and BP are promising adsorbents for the removal of toxic dye CR.

Batch adsorption experiments were carried out for the removal of dye congo red (CR) from aqueous solutions using bagasse charcoal (BC) and banana peels (BP). Experiments were carried out as a function of contact time, initial dye concentration, adsorbent dose and ionic strength. The results showed that the amount of dye adsorbed increased with increasing initial dye concentration and contact time. The kinetics of basic dye adsorption nicely followed the pseudo second-order rate expression and demonstrates that intraparticle diffusion plays a significant role in the adsorption process. The adsorption data fitted well with Langmuir, Freundlich, Temkin, Dubinin and Radushkevich and Generalized isotherms. The characteristic parameters for each model have been determined. The Langmuir isotherm gave the best correlation for the adsorption of dye congo red on both the adsorbents. The monolayer saturation capacity was found to be 45.3 and 44.4 mg/g for BC and BP respectively. The value of separation factor (RL) insinuates that BC and BP can be used as effective adsorbents. The results of the present study corroborate that BC and BP are promising adsorbents for the removal of toxic dye CR.

Batch adsorption experiments were carried out for the removal of dye congo red (CR) from aqueous solutions using bagasse charcoal (BC) and banana peels (BP). Experiments were carried out as a function of contact time, initial dye concentration, adsorbent dose and ionic strength. The results showed that the amount of dye adsorbed increased with increasing initial dye concentration and contact time. The kinetics of basic dye adsorption nicely followed the pseudo second-order rate expression and demonstrates that intraparticle diffusion plays a significant role in the adsorption process. The adsorption data fitted well with Langmuir, Freundlich, Temkin, Dubinin and Radushkevich and Generalized isotherms. The characteristic parameters for each model have been determined. The Langmuir isotherm gave the best correlation for the adsorption of dye congo red on both the adsorbents. The monolayer saturation capacity was found to be 45.3 and 44.4 mg/g for BC and BP respectively. The value of separation factor (RL) insinuates that BC and BP can be used as effective adsorbents. The results of the present study corroborate that BC and BP are promising adsorbents for the removal of toxic dye CR.

Batch adsorption experiments were carried out for the removal of dye congo red (CR) from aqueous solutions using bagasse charcoal (BC) and banana peels (BP). Experiments were carried out as a function of contact time, initial dye concentration, adsorbent dose and ionic strength. The results showed that the amount of dye adsorbed increased with increasing initial dye concentration and contact time. The kinetics of basic dye adsorption nicely followed the pseudo second-order rate expression and demonstrates that intraparticle diffusion plays a significant role in the adsorption process. The adsorption data fitted well with Langmuir, Freundlich, Temkin, Dubinin and Radushkevich and Generalized isotherms. The characteristic parameters for each model have been determined. The Langmuir isotherm gave the best correlation for the adsorption of dye congo red on both the adsorbents. The monolayer saturation capacity was found to be 45.3 and 44.4 mg/g for BC and BP respectively. The value of separation factor (RL) insinuates that BC and BP can be used as effective adsorbents. The results of the present study corroborate that BC and BP are promising adsorbents for the removal of toxic dye CR.

The "folding algorithm"\cite{fold1} is a matrix product state algorithm for simulating quantum systems that involves a spatial evolution of a matrix product state. Hence, the computational effort of this algorithm is controlled by the temporal entanglement. We show that this temporal entanglement is, in many cases, equal to the spatial entanglement of a modified Hamiltonian. This inspires a modification to the folding algorithm, that we call the "hybrid algorithm". We find that this leads to improved accuracy for the same numerical effort. We then use these algorithms to study relaxation in a transverse plus parallel field Ising model, finding persistent quasi-periodic oscillations for certain choices of initial conditions., Comment: 16 pages, 11 figures

The design is described of the pre-cast segmental linings for the Waterview three-lane motorway tunnel project. The project involves the construction of the largest tunnel boring machine (TBM) driven tunnel in the Asia-Pacific region, and includes tunnels which are 2.4 km long with a 13.1 m internal diameter. The segmental lining has a configuration of nine interconnected segments and a smaller key segment about one third the size of a typical segment. The rings are straight, left tapered or right tapered, with the taper based on the minimum horizontal radius of curvature along the alignment. The lining is equipped with a groove for an elastomeric waterproofing gasket which provides a seal to resist a maximum possible water pressure of 4.2 bars. Segments and rings are connected using spear bolts which are removed once grouting is completed. There are two shear cone recesses on the intrados face of each segment to facilitate the use of a TBM vacuum pad segment erector and primary grouting of the annulus is undertaken from within the TBM tail skin. The precast concrete lining has been designed to be steel fibre reinforced in combination with steel bar ladders placed close to the segment faces to resist bursting stresses from TBM thrust rams and segment-to-segment bearing. Design and analytical methods employed included 2D bedded beam and 3D plate element modelling., The design is described of the pre-cast segmental linings for the Waterview three-lane motorway tunnel project. The project involves the construction of the largest tunnel boring machine (TBM) driven tunnel in the Asia-Pacific region, and includes tunnels which are 2.4 km long with a 13.1 m internal diameter. The segmental lining has a configuration of nine interconnected segments and a smaller key segment about one third the size of a typical segment. The rings are straight, left tapered or right tapered, with the taper based on the minimum horizontal radius of curvature along the alignment. The lining is equipped with a groove for an elastomeric waterproofing gasket which provides a seal to resist a maximum possible water pressure of 4.2 bars. Segments and rings are connected using spear bolts which are removed once grouting is completed. There are two shear cone recesses on the intrados face of each segment to facilitate the use of a TBM vacuum pad segment erector and primary grouting of the annulus is undertaken from within the TBM tail skin. The precast concrete lining has been designed to be steel fibre reinforced in combination with steel bar ladders placed close to the segment faces to resist bursting stresses from TBM thrust rams and segment-to-segment bearing. Design and analytical methods employed included 2D bedded beam and 3D plate element modelling.

The "folding algorithm"\cite{fold1} is a matrix product state algorithm for simulating quantum systems that involves a spatial evolution of a matrix product state. Hence, the computational effort of this algorithm is controlled by the temporal entanglement. We show that this temporal entanglement is, in many cases, equal to the spatial entanglement of a modified Hamiltonian. This inspires a modification to the folding algorithm, that we call the "hybrid algorithm". We find that this leads to improved accuracy for the same numerical effort. We then use these algorithms to study relaxation in a transverse plus parallel field Ising model, finding persistent quasi-periodic oscillations for certain choices of initial conditions., Comment: 16 pages, 11 figures

We study the problem of disorder-free metals near a continuous Ising nematic quantum critical point in $d=3+1$ dimensions. We begin with perturbation theory in the `Yukawa' coupling between the electrons and undamped bosons (nematic order parameter fluctuations) and show that the perturbation expansion breaks down below energy scales where the bosons get substantially Landau damped. Above this scale however, we find a regime in which low-energy fermions obtain an imaginary self-energy that varies linearly with frequency, realizing the `marginal Fermi liquid' phenomenology\cite{Varma}. We discuss a large N theory in which the marginal Fermi liquid behavior is enhanced while the role of Landau damping is suppressed, and show that quasiparticles obtain a decay rate parametrically larger than their energy., Comment: 5 pages, 2 figures

We study the problem of disorder-free metals near a continuous Ising nematic quantum critical point in $d=3+1$ dimensions. We begin with perturbation theory in the `Yukawa' coupling between the electrons and undamped bosons (nematic order parameter fluctuations) and show that the perturbation expansion breaks down below energy scales where the bosons get substantially Landau damped. Above this scale however, we find a regime in which low-energy fermions obtain an imaginary self-energy that varies linearly with frequency, realizing the `marginal Fermi liquid' phenomenology\cite{Varma}. We discuss a large N theory in which the marginal Fermi liquid behavior is enhanced while the role of Landau damping is suppressed, and show that quasiparticles obtain a decay rate parametrically larger than their energy., Comment: 5 pages, 2 figures

We present an electromechanical stability analysis of passivated parallel-plate electrostatic actuators in conductive dielectric media and show that the pull-in instability can be eliminated by tuning the applied frequency below a design-dependent stability limit. A partial instability region is also obtained, where the actuator jumps from the pull-in displacement to another stable position within the gap. The results predict that the stability limit is always greater than the critical actuation frequency, and therefore any device that is feasible to actuate in a conductive fluid can be operated with stability over the full range of motion. (C) 2010 American Institute of Physics. [doi:10.1063/1.3389491]

We present an electromechanical stability analysis of passivated parallel-plate electrostatic actuators in conductive dielectric media and show that the pull-in instability can be eliminated by tuning the applied frequency below a design-dependent stability limit. A partial instability region is also obtained, where the actuator jumps from the pull-in displacement to another stable position within the gap. The results predict that the stability limit is always greater than the critical actuation frequency, and therefore any device that is feasible to actuate in a conductive fluid can be operated with stability over the full range of motion. (C) 2010 American Institute of Physics. [doi:10.1063/1.3389491]

Pulsed laser treatment of an individual multiwall carbon nanotube induced selective exfoliation of the amorphous carbon contamination layer. The multiwall carbon nanotube (MWCNT) was exposed to a 248 nm excimer laser. After the treatment, transmission electron microscopy images show that the amorphous layer has expanded and separated from the crystalline MWCNT walls. This interesting observation has implications for laser cleaning and possible thinning of MWCNTs to reduce the radial dimensions. (C) 2007 American Institute of Physics.

Pulsed laser treatment of an individual multiwall carbon nanotube induced selective exfoliation of the amorphous carbon contamination layer. The multiwall carbon nanotube (MWCNT) was exposed to a 248 nm excimer laser. After the treatment, transmission electron microscopy images show that the amorphous layer has expanded and separated from the crystalline MWCNT walls. This interesting observation has implications for laser cleaning and possible thinning of MWCNTs to reduce the radial dimensions. (C) 2007 American Institute of Physics.