RADIO FREQUENCY SIGNAL PROCESSING WITH MICROELECTROMECHANICAL RESONATING SYSTEMS

This thesis presents a study of the dynamics and applications of a high frequency micromechanical (MEMS) resonator. Mechanical systems, which have been scaled in dimension to the micron scale, show promise for replacing electrical resonant systems, which have larger physical size and lower performance. MEMS resonators can also be integrated into a chip containing conventional field effect transistors. A process incorporating both frequency dependent resonant systems as well as analog and digital electronics will enable all hardware in a communication architecture to be placed on a single silicon chip. In this study, a micron-sized circular membrane, suspended in the middle and clamped on the periphery, forms the basis of the resonant mechanical system. A small degree of curvature is fabricated into the resonator, which serves to stiffen the device and hence increase the frequency range. A microheater, defined in proximity to the resonator, is used to induce motion in the membrane. The frequency dependent response of the membrane is then detected through either interferometric or piezoresistive techniques. Resistive actuation and detection allow the membrane and actuators to be fabricated into a single plane of silicon, facilitating integration of the complete MEMS system. It is demonstrated how both the resonators and transducers can be implemented into two CMOS processes. Both designs incorporate the mechanical system as well as the solid-state electronics for output signal detection into a single fabrication process. Finally, the dynamics of the MEMS resonator, both in the linear and non-linear regime, are explored. The micron-sized mechanical system is demonstrated to perform several types of signal processing that are critical for wireless communication architectures. These studies shed new light on how the nonlinear dynamics of these systems may be characterized and harnessed for new applications

Cell arrest and cell death in mammalian preimplantation development

The causes, modes, biological role and prospective significance of cell death in preimplantation development in humans and other mammals are still poorly understood. Early bovine embryos represent a very attractive experimental model for the investigation of this fundamental and important issue. To obtain reference data on the temporal and spatial occurrence of cell death in early bovine embryogenesis, three-dimensionally preserved embryos of different ages and stages of development up to hatched blastocysts were examined in toto by confocal laser scanning microscopy. In parallel, transcript abundance profiles for selected apoptosis-related genes were analyzed by real-time reverse transcriptase-polymerase chain reaction. Our study documents that in vitro as well as in vivo, the first four cleavage cycles are prone to a high failure rate including different types of permanent cell cycle arrest and subsequent non-apoptotic blastomere death. In vitro produced and in vivo derived blastocysts showed a significant incidence of cell death in the inner cell mass (ICM), but only in part with morphological features of apoptosis. Importantly, transcripts for CASP3, CASP9, CASP8 and FAS/FASLG were not detectable or found at very low abundances. In vitro and in vivo, errors and failures of the first and the next three cleavage divisions frequently cause immediate embryo death or lead to aberrant subsequent development, and are the main source of developmental heterogeneity. A substantial occurrence of cell death in the ICM even in fast developing blastocysts strongly suggests a regular developmentally controlled elimination of cells, while the nature and mechanisms of ICM cell death are unclear. Morphological findings as well as transcript levels measured for important apoptosis-related genes are in conflict with the view that classical caspase-mediated apoptosis is the major cause of cell death in early bovine development

Earth observations into action: the systemic integration of earth observation applications into national risk reduction decision structures

Purpose - As stated in the United Nations Global Assessment Report 2022 Concept Note, decision-makers everywhere need data and statistics that are accurate, timely, sufficiently disaggregated, relevant, accessible and easy to use. The purpose of this paper is to demonstrate scalable and replicable methods to advance and integrate the use of earth observation (EO), specifically ongoing efforts within the Group on Earth Observations (GEO) Work Programme and the Committee on Earth Observation Satellites (CEOS) Work Plan, to support risk-informed decision-making, based on documented national and subnational needs and requirements. Design/methodology/approach - Promotion of open data sharing and geospatial technology solutions at national and subnational scales encourages the accelerated implementation of successful EO applications. These solutions may also be linked to specific Sendai Framework for Disaster Risk Reduction (DRR) 2015–2030 Global Targets that provide trusted answers to risk-oriented decision frameworks, as well as critical synergies between the Sendai Framework and the 2030 Agenda for Sustainable Development. This paper provides examples of these efforts in the form of platforms and knowledge hubs that leverage latest developments in analysis ready data and support evidence-based DRR measures. Findings - The climate crisis is forcing countries to face unprecedented frequency and severity of disasters. At the same time, there are growing demands to respond to policy at the national and international level. EOs offer insights and intelligence for evidence-based policy development and decision-making to support key aspects of the Sendai Framework. The GEO DRR Working Group and CEOS Working Group Disasters are ideally placed to help national government agencies, particularly national Sendai focal points to learn more about EOs and understand their role in supporting DRR. Originality/value - The unique perspective of EOs provide unrealized value to decision-makers addressing DRR. This paper highlights tangible methods and practices that leverage free and open source EO insights that can benefit all DRR practitioners

Surgical versus conservative treatment for lumbar disc herniation: a prospective cohort study.

OBJECTIVES Evidence comparing the effectiveness of surgical and conservative treatment of symptomatic lumbar disc herniation is controversial. We sought to compare short-term and long-term effectiveness of surgical and conservative treatment in sciatica symptom severity and quality of life in patients with lumbar disc herniation in a routine clinical setting. METHODS A prospective cohort study of a routine clinical practice registry consisting of 370 patients. Outcome measures were the North American Spine Society questionnaire and the 36-Item Short-Form Health Survey to assess patient-reported back pain, physical function, neurogenic symptoms and quality of life. Primary outcomes were back pain at 6 and 12 weeks. Standard open discectomy was assessed versus conservative interventions at 6, 12, 52 and 104 weeks. We filled in missing outcome variable values with multiple imputation, accounted for repeated measures within patients with mixed-effects models and adjusted baseline group differences in relevant prognostic indicators by inverse probability of treatment weighting. RESULTS Surgical treatment patients reported less back pain at 6 weeks than those receiving conservative therapy (-0.97; 95% CI -1.89 to -0.09), were more likely to report ≥50% decrease in back pain symptoms from baseline to 6 weeks (48% vs 17%, risk difference: 0.34; 95% CI 0.16 to 0.47) and reported less physical function disability at 52 weeks (-3.7; 95% CI -7.4 to -0.1). The other assessments showed minimal between-group differences with CIs, including the null effect. CONCLUSIONS Compared with conservative therapy, surgical treatment provided faster relief from back pain symptoms in patients with lumbar disc herniation, but did not show a benefit over conservative treatment in midterm and long-term follow-up

Cyclic game dynamics driven by iterated reasoning

Recent theories from complexity science argue that complex dynamics are ubiquitous in social and economic systems. These claims emerge from the analysis of individually simple agents whose collective behavior is surprisingly complicated. However, economists have argued that iterated reasoning--what you think I think you think--will suppress complex dynamics by stabilizing or accelerating convergence to Nash equilibrium. We report stable and efficient periodic behavior in human groups playing the Mod Game, a multi-player game similar to Rock-Paper-Scissors. The game rewards subjects for thinking exactly one step ahead of others in their group. Groups that play this game exhibit cycles that are inconsistent with any fixed-point solution concept. These cycles are driven by a "hopping" behavior that is consistent with other accounts of iterated reasoning: agents are constrained to about two steps of iterated reasoning and learn an additional one-half step with each session. If higher-order reasoning can be complicit in complex emergent dynamics, then cyclic and chaotic patterns may be endogenous features of real-world social and economic systems.Comment: 8 pages, 4 figures, and supplementary informatio

Moderators, Mediators, and Prognostic Indicators of Treatment With Hip Arthroscopy or Physical Therapy for Femoroacetabular Impingement Syndrome: Secondary Analyses From the Australian FASHIoN Trial.

BACKGROUND Although randomized controlled trials comparing hip arthroscopy with physical therapy for the treatment of femoroacetabular impingement (FAI) syndrome have emerged, no studies have investigated potential moderators or mediators of change in hip-related quality of life. PURPOSE To explore potential moderators, mediators, and prognostic indicators of the effect of hip arthroscopy and physical therapy on change in 33-item international Hip Outcome Tool (iHOT-33) score for FAI syndrome. STUDY DESIGN Cohort study; Level of evidence, 2. METHODS Overall, 99 participants were recruited from the clinics of orthopaedic surgeons and randomly allocated to treatment with hip arthroscopy or physical therapy. Change in iHOT-33 score from baseline to 12 months was the dependent outcome for analyses of moderators, mediators, and prognostic indicators. Variables investigated as potential moderators/prognostic indicators were demographic variables, symptom duration, alpha angle, lateral center-edge angle (LCEA), Hip Osteoarthritis MRI Scoring System (HOAMS) for selected magnetic resonance imaging (MRI) features, and delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) score. Potential mediators investigated were change in chosen bony morphology measures, HOAMS, and dGEMRIC score from baseline to 12 months. For hip arthroscopy, intraoperative procedures performed (femoral ostectomy ± acetabular ostectomy ± labral repair ± ligamentum teres debridement) and quality of surgery graded by a blinded surgical review panel were investigated for potential association with iHOT-33 change. For physical therapy, fidelity to the physical therapy program was investigated for potential association with iHOT-33 change. RESULTS A total of 81 participants were included in the final moderator/prognostic indicator analysis and 85 participants in the final mediator analysis after exclusion of those with missing data. No significant moderators or mediators of change in iHOT-33 score from baseline to 12 months were identified. Patients with smaller baseline LCEA (β = -0.82; P = .034), access to private health care (β = 12.91; P = .013), and worse baseline iHOT-33 score (β = -0.48; P < .001) had greater iHOT-33 improvement from baseline to 12 months, irrespective of treatment allocation, and thus were prognostic indicators of treatment response. Unsatisfactory treatment fidelity was associated with worse treatment response (β = -24.27; P = .013) for physical therapy. The quality of surgery and procedures performed were not associated with iHOT-33 change for hip arthroscopy (P = .460-.665 and P = .096-.824, respectively). CONCLUSION No moderators or mediators of change in hip-related quality of life were identified for treatment of FAI syndrome with hip arthroscopy or physical therapy in these exploratory analyses. Patients who accessed the Australian private health care system, had smaller LCEAs, and had worse baseline iHOT-33 scores, experienced greater iHOT-33 improvement, irrespective of treatment allocation

Melting, bubble-like expansion and explosion of superheated plasmonic nanoparticles

We report on time-resolved coherent diffraction imaging of gas-phase silver nanoparticles, strongly heated via their plasmon resonance. The x-ray diffraction images reveal a broad range of phenomena for different excitation strengths, from simple melting over strong cavitation to explosive disintegration. Molecular dynamics simulations fully reproduce this behavior and show that the heating induces rather similar trajectories through the phase diagram in all cases, with the very different outcomes being due only to whether and where the stability limit of the metastable superheated liquid is crossed.Comment: 17 pages, 8 figures (including supplemental material

Decreased brain venous vasculature visibility on susceptibility-weighted imaging venography in patients with multiple sclerosis is related to chronic cerebrospinal venous insufficiency.

BACKGROUND: The potential pathogenesis between the presence and severity of chronic cerebrospinal venous insufficiency (CCSVI) and its relation to clinical and imaging outcomes in brain parenchyma of multiple sclerosis (MS) patients has not yet been elucidated. The aim of the study was to investigate the relationship between CCSVI, and altered brain parenchyma venous vasculature visibility (VVV) on susceptibility-weighted imaging (SWI) in patients with MS and in sex- and age-matched healthy controls (HC). METHODS: 59 MS patients, 41 relapsing-remitting and 18 secondary-progressive, and 33 HC were imaged on a 3T GE scanner using pre- and post-contrast SWI venography. The presence and severity of CCSVI was determined using extra-cranial and trans-cranial Doppler criteria. Apparent total venous volume (ATVV), venous intracranial fraction (VIF) and average distance-from-vein (DFV) were calculated for various vein mean diameter categories: .9 mm. RESULTS: CCSVI criteria were fulfilled in 79.7% of MS patients and 18.2% of HC (p < .0001). Patients with MS showed decreased overall ATVV, ATVV of veins with a diameter < .3 mm, and increased DFV compared to HC (all p < .0001). Subjects diagnosed with CCSVI had significantly increased DFV (p < .0001), decreased overall ATVV and ATVV of veins with a diameter < .3 mm (p < .003) compared to subjects without CCSVI. The severity of CCSVI was significantly related to decreased VVV in MS (p < .0001) on pre- and post-contrast SWI, but not in HC. CONCLUSIONS: MS patients with higher number of venous stenoses, indicative of CCSVI severity, showed significantly decreased venous vasculature in the brain parenchyma. The pathogenesis of these findings has to be further investigated, but they suggest that reduced metabolism and morphological changes of venous vasculature may be taking place in patients with MS