Measurement accuracies in band-limited extrapolation

The problem of numerical instability associated with extrapolation algorithms is addressed. An attempt is made to estimate the bounds for the acceptable errors and to place a ceiling on the measurement accuracy and computational accuracy needed for the extrapolation. It is shown that in band limited (or visible angle limited) extrapolation the larger effective aperture L' that can be realized from a finite aperture L by over sampling is a function of the accuracy of measurements. It is shown that for sampling in the interval L/b absolute value of xL, b1 the signal must be known within an error e sub N given by e sub N squared approximately = 1/4(2kL') cubed (e/8b L/L')(2kL') where L is the physical aperture, L' is the extrapolated aperture, and k = 2pi lambda

Self-Consistent-Field Study of Adsorption and Desorption Kinetics of Polyethylene Melts on Graphite and Comparison with Atomistic Simulations

A method is formulated, based on combining self-consistent field theory with dynamically corrected transition state theory, for estimating the rates of adsorption and desorption of end-constrained chains (e.g. by crosslinks or entanglements) from a polymer melt onto a solid substrate. This approach is tested on a polyethylene/graphite system, where the whole methodology is parametrized by atomistically detailed molecular simulations. For short-chain melts, which can still be addressed by molecular dynamics simulations with reasonable computational resources, the self-consistent field approach gives predictions of the adsorption and desorption rate constants which are gratifyingly close to molecular dynamics estimates.Comment: 18 pages, 10 figure

Modern Spectral Climate Patterns in Rhythmically Deposited Argillites of the Gowganda Formation (Early Proterozoic), Southern Ontario, Canada

Rhythmically deposited argillites of the Gowganda Formation (ca. 2.0–2.5 Ga) probably formed in a glacial setting. Drop stones and layered sedimentary couplets in the rock presumably indicate formation in a lacustrine environment with repeating freeze–thaw cycles. It is plausible that temporal variations in the thickness of sedimentary layers are related to interannual climatic variability, e.g. average seasonal temperature could have influenced melting and the amount of sediment source material carried to the lake. A sequence of layer couplet thickness measurements was made from high-resolution digitized photographs taken at an outcrop in southern Ontario, Canada. The frequency spectrum of thickness measurements displays patterns that resemble some aspects of modern climate. Coherent periodic modes in the thickness spectrum appear at 9.9–10.7 layer couplets and at 14.3 layer couplets. It is unlikely that these coherent modes result from random processes. Modern instrument records of regional temperature and rainfall display similar spectral patterns, with some datasets showing significant modes near 14 yr in both parameters. Rainfall and temperature could have affected sedimentary layering in the Gowganda argillite sequence, and climate modulation of couplet thickness emerges as the most likely explanation of the observed layering pattern. If this interpretation is correct, the layer couplets represent predominantly annual accumulations of sediment (i.e. they are varves), and the thickness spectrum provides a glimpse of Early Proterozoic climatic variability. The presence of interannual climate patterns is not unanticipated, but field evidence presented here may be of some value in developing a climate theory for the Early Proterozoic

Inhaler technique mastery and maintenance in healthcare professionals trained on different devices

Peer reviewedPostprin

Παρασκευή καταλυτικού φορέα με υγρές χημικές μεθόδους - Μελέτη των παραμέτρων που επηρεάζουν την πρόσφυση στο κεραμικό υπόστρωμα

91 σ.Αντικείμενο της διπλωματικής αυτής εργασίας αποτέλεσε η μελέτη της παρασκευής καταλυτικού φορέα με τη χρησιμοποίηση υγρών χημικών μεθόδων. Οι μέθοδοι αυτές ήταν η συγκαταβύθιση και η υβριδική μέθοδος λύματος-πυκτής(sol-gel) με τη χρήση υπερδιακλαδισμένων πολυμερών(Βιομιμητική σύνθεση). Έλαβε επίσης χώρα μελέτη των παραμέτρων που επηρεάζουν την πρόσφυση στο κεραμικό υπόστρωμα.The purpose of this thesis was the study of manufacturing catalysts using wet chemical methods. These methods were the coprecipetation and the hybrid sewage-PSVT (sol-gel) with the use of highly active polymers (Biomimetic synthesis). We examined also the parameters affecting the adhesion to the ceramic substrate.Σαράντος Ν. Κρητικό

Technology needs assessment of an atmospheric observation system for tropospheric research missions, part 1

The technology advancements needed to implement the atmospheric observation satellite systems for air quality research were identified. Tropospheric measurements are considered. The measurements and sensors are based on a model of knowledge objectives in atmospheric science. A set of potential missions and attendant spacecraft and sensors is postulated. The results show that the predominant technology needs will be in passive and active sensors for accurate and frequent global measurements of trace gas concentration profiles

Parents\u27 School-related Concerns and Perceived Strengths in Youth with Spina Bifida

BackgroundAlthough the academic difficulties of children with spina bifida (SB) are well-documented, there is limited literature on parents\u27 views of their children\u27s school experiences and school-related supportive services. Thus, the current study examined parents\u27 school-related concerns, as well as perceived areas of strength, among children with SB.MethodsUsing a mixed-methods approach, 30 families (29 mothers and 19 fathers) of children with SB (ages 8–15 years) completed questionnaires and interviews. Content analysis was used to generate themes from interview data about parents\u27 school-related concerns and perceptions of their child\u27s strengths.ResultsOverall, six themes emerged when assessing both parents\u27 concerns and perceived strengths. Some parents did not endorse school concerns or strengths for their child. However, other parents described concerns related to academic performance, cognitive abilities, lack of school support, missed school and/or class time and disengagement, as well as strengths such as academic skills, cognitive abilities, persistence, self-advocacy and agreeableness. Despite parents\u27 concerns about their children\u27s academic performance, quantitative data revealed that less than 50% of children had received a neuropsychological evaluation and/or academic accommodations; additional quantitative data supported the qualitative findings.ConclusionsThe mixed-methods approach used in this study provides a richer understanding of parents\u27 experiences in the school setting when they have a child with SB. Results can inform clinical practice, identifying a need to improve academic support for children with SB and help parents manage education-related stressors

Clinical Utility of Cardiovascular Magnetic Resonance Imaging for Diagnosis of Acute Myocarditis

Cardiac magnetic resonance imaging (CMR) is a novel imaging technique that may help differentiate between myocarditis and acute coronary syndrome and compares favorably to other imaging techniques because it also provides information on tissue consistency and characteristics. We herein present a case, whereby CMR was most useful in providing such a differential diagnosis

Clinical Utility of Cardiovascular Magnetic Resonance Imaging for Diagnosis of Acute Myocarditis

A 49 year-old patient with past medical history significant for arterial hypertension (treated with telmisartan 80 mg daily), presented to the emergency department with 18-hour gastric discomfort and fatigue. Five days prior to this presentation the patient had an episode of febrile gastroenteritis. The evening prior to presentation the patient had blood chemistries performed at an outside institution, where an increase of myocardial enzymes (troponin and CPK-MB) were noted. On presentation the patient was uncomfortable due to abdominal pain, but the clinical examination was almost normal. Blood pressure was 150/80 mmHg and heart rate was 60 beats/min. Cardiac S1 and S2 sounds where audible, without additional cardiac tones, murmurs, pericardial or pleural friction. There was no jugular venous distention, rales or peripheral edema present. Admission 12-lead electrocardiogram (ECG) demonstrated normal sinus rhythm with a rate of 60 beats/min, and early repolarization pattern with a slight J-point elevation in the lateral leads (I, aVL, V5, V6)