An observer and regulator for linear systems with pure and distributed delays

M.S.Edward W. Kame

Investigation into the molar feeding ratio and temperature dependence on the replacement reaction between platinum ions and silver nanoparticles

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.Cataloged from PDF version of thesis.Includes bibliographical references (p. 21).The deliberate structuring of bimetallic nanoparticles has useful applications in both fuel cell applications and biomedical research. This thesis studies the replacement reaction between platinum ions and silver nanoparticles, with the goal of synthesizing platinum-shelled silver nanoparticles. Specifically, the molar feeding ratio and the temperature dependence on the reaction were investigated. At low levels of supplied platinum, the nanoshells were only partially formed, but at a 1:1 molar ratio, non-uniform thickness nanoshells were formed with large amounts of silver on the surface. The temperature dependence showed increasingly thick shell formation; however, cyclic voltammetry measurements indicated the surface of the nanoparticles contained excessive levels of silver, deeming the particles inadequate for use as fuel cell catalysts. Through high temperature reactions, the surface plasmon resonance excitations peaks of the silver nanoparticles were shifted 100nm higher, pushing the peaks closer to the visible spectrum from the deep ultraviolet region.by Archimedes Stuk.S.B

System for Transmitting and Receiving Electromagnetic Radiation

A system for transmitting and receiving electromagnetic radiation includes a beam splitter and a transceiver. The beam splitter is configured to separate an optical pulse into a pump pulse and a probe pulse. The transceiver may include a transmitter switch and a receiver switch. The pump pulse is directed toward the transmitter switch and the probe pulse is directed towards the receiver switch. Electromagnetic radiation is emitted from the transceiver when the pump pulse strikes the transmitter switch. The electromagnetic radiation may be terahertz radiation in either a pulsed or continuous wave form

Planting the Seeds: Orchestral Music Education as a Context for Fostering Growth Mindsets

Growth mindset is an important aspect of children\u27s socioemotional development and is subject to change due to environmental influence. Orchestral music education may function as a fertile context in which to promote growth mindset; however, this education is not widely available to children facing economic hardship. This study examined whether participation in a program of orchestral music education was associated with higher levels of overall growth mindset and greater change in levels of musical growth mindset among children placed at risk by poverty. After at least 2 years of orchestral participation, students reported significantly higher levels of overall growth mindset than their peers; participating students also reported statistically significant increases in musical growth mindset regardless of the number of years that they were enrolled in orchestral music education. These findings have implications for future research into specific pedagogical practices that may promote growth mindset in the context of orchestral music education and more generally for future studies of the extra-musical benefits of high-quality music education

7-[4-(5,7-Dimethyl-1,8-naphthyridin-2-yl­oxy)phen­oxy]-2,4-dimethyl-1,8-naphthyridine methanol disolvate

The title compound, C26H22N4O2·2CH3OH, was synthesized and characterized by 1H NMR spectroscopy and X-ray structure analysis. There is one half-mol­ecule in the asymmetric unit with a centre of symmetry located at the centre of the benzene ring. The two bridged naphthyridine ring systems are in an anti­parallel orientation. In the crystal structure, O—H⋯N, C—H⋯O and C—H⋯N inter­actions define the packing

Self-reported symptom severity, general health, and impairment in post-acute phases of COVID-19: retrospective cohort study of Swedish public employees

This study aimed to examine current symptom severity and general health in a sample of primarily non-hospitalized persons with polymerase chain reaction (PCR) confirmed COVID-19 in comparison to PCR negative controls. During the first quarter of 2021, we conducted an online survey among public employees in West Sweden, with a valid COVID-19 test result. The survey assessed past-month severity of 28 symptoms and signs, self-rated health, the WHO Disability Assessment Schedule (WHODAS) 2.0 and illness severity at the time of test. We linked participants’ responses to their SARS-CoV-2 PCR tests results. We compared COVID-19 positive and negative participants using univariable and multivariable regression analyses. Out of 56,221 invited, 14,222 (25.3%) responded, with a response rate of 50% among SARS-CoV-2 positive individuals. Analysis included 10,194 participants (86.4% women, mean age 45\ua0years) who tested positive 4–12\ua0weeks (N = 1425; subacute) and > 12\ua0weeks (N = 1584; postcovid) prior to the survey, and 7185 PCR negative participants who did not believe that they had had COVID-19. Symptoms were highly prevalent in all groups, with worst symptoms in subacute phase participants, followed by postcovid phase and PCR negative participants. The most specific symptom for COVID-19 was loss of smell or taste. Both WHODAS 2.0 score and self-rated health were worst in subacute participants, and modestly worse in postcovid participants than in negative controls. Female gender, older age and acute illness severity had larger effects on self-rated health and WHODAS 2.0 score in PCR positive participants than in PCR negative. Studies with longer follow-up are needed to determine the long-term improvement after COVID-19

Portable Unit for Metabolic Analysis

The Portable Unit for Metabolic Analysis (PUMA) is an instrument that measures several quantities indicative of human metabolic function. Specifically, this instrument makes time-resolved measurements of temperature, pressure, flow, and the partial pressures of oxygen and carbon dioxide in breath during both inhalation and exhalation. Portable instruments for measuring these quantities have been commercially available, but the response times of those instruments are too long to enable temporal resolution of phenomena on the time scales of human respiration cycles. In contrast, the response time of the PUMA is significantly shorter than characteristic times of human respiration phenomena, making it possible to analyze varying metabolic parameters, not only on sequential breath cycles but also at successive phases of inhalation and exhalation within the same breath cycle. In operation, the PUMA is positioned to sample breath near the subject s mouth. Commercial off-the-shelf sensors are used for three of the measurements: a miniature pressure transducer for pressure, a thermistor for temperature, and an ultrasonic sensor for flow. Sensors developed at Glenn Research Center are used for measuring the partial pressures of oxygen and carbon dioxide: The carbon dioxide sensor exploits the relatively strong absorption of infrared light by carbon dioxide. Light from an infrared source passes through the stream of inhaled or exhaled gas and is focused on an infrared- sensitive photodetector. The oxygen sensor exploits the effect of oxygen in quenching the fluorescence of ruthenium-doped organic molecules in a dye on the tip of an optical fiber. A blue laser diode is used to excite the fluorescence, and the optical fiber carries the fluorescent light to a photodiode, the temporal variation of the output of which bears a known relationship with the rate of quenching of fluorescence and, hence, with the partial pressure of oxygen. The outputs of the sensors are digitized, preprocessed by a small onboard computer, and then sent wirelessly to a desktop computer, where the collected data are analyzed and displayed. In addition to the raw data on temperature, pressure, flow, and mole fractions of oxygen and carbon dioxide, the display can include volumetric oxygen consumption, volumetric carbon dioxide production, respiratory equivalent ratio, and volumetric flow rate of exhaled gas

Псевдомиксома брюшной полости: клиническое наблюдение

Abdominal pseudomyxoma is a rare condition without any specific symptoms. Abdominal pain, nausea or ascites often can be the only symptoms of abdominal pseudomyxoma for a long time after the disease onset. In the majority of cases when patients present with unspecific abdominal symptoms, ultrasound and endoscopy are performed. However, these diagnostic procedures have low sensivity for detection of abdominal pseudomyxoma, which results in late diagnosis and unfavourable prognosis. In the given clinical case importance of CT in patients with abdomianl pain and ascites in the absence of other known cause is emphasized.Псевдомиксома брюшной полости - достаточно редкое заболевание, не имеющее специфической клинической картины. Единственными симптомами псевдомиксомы могут являться боль в животе, тошнота или увеличение живота в объеме, напоминающее асцит. В большинстве случаев при обследовании пациентов, предъявляющих жалобы, характерные для заболеваний желудочно-кишечного тракта, используются такие методы исследования, как УЗИ, гастро- и колоноскопия. В диагностике псевдомиксомы брюшной полости данные методы обладают низкой чувствительностью, что приводит к задержке в постановке диагноза и неблагоприятному прогнозу. В приведенном клиническом наблюдении подчеркивается важность применения КТ при обследовании пациентов с асцитом и болевым синдромом без явной причины

Making the most of what we have: Application of extrapolation approaches in radioecological wildlife transfer models

© 2015 The Authors. We will never have data to populate all of the potential radioecological modelling parameters required for wildlife assessments. Therefore, we need robust extrapolation approaches which allow us to make best use of our available knowledge. This paper reviews and, in some cases, develops, tests and validates some of the suggested extrapolation approaches.The concentration ratio (CRproduct-diet or CRwo-diet) is shown to be a generic (trans-species) parameter which should enable the more abundant data for farm animals to be applied to wild species.An allometric model for predicting the biological half-life of radionuclides in vertebrates is further tested and generally shown to perform acceptably. However, to fully exploit allometry we need to understand why some elements do not scale to expected values.For aquatic ecosystems, the relationship between log10(a) (a parameter from the allometric relationship for the organism-water concentration ratio) and log(Kd) presents a potential opportunity to estimate concentration ratios using Kd values.An alternative approach to the CRwo-media model proposed for estimating the transfer of radionuclides to freshwater fish is used to satisfactorily predict activity concentrations in fish of different species from three lakes. We recommend that this approach (REML modelling) be further investigated and developed for other radionuclides and across a wider range of organisms and ecosystems.Ecological stoichiometry shows potential as an extrapolation method in radioecology, either from one element to another or from one species to another.Although some of the approaches considered require further development and testing, we demonstrate the potential to significantly improve predictions of radionuclide transfer to wildlife by making better use of available data