1,576 research outputs found
Research in and application of state variable feedback design of guidance control systems for aerospace vehicles Progress report
Weighted least squares parameter estimation, Kalman filter, and random search problems for aerospace guidance control system desig
Control system design using optimization techniques Final report
Optimization techniques for control of fuel valve systems for air breathing jet engines and 40-60 inlet control problem
Photonic mode density effects on single-molecule fluorescence blinking
We investigated the influence of the photonic mode density (PMD) on the
triplet dynamics of individual chromophores on a dielectric interface by
comparing their response in the presence and absence of a nearby gold film.
Lifetimes of the excited singlet state were evaluated in ordet to measure
directly the PMD at the molecules position. Triplet state lifetimes were
simultaneously determined by statistical analysis of the detection time of the
fluorescence photons. The observed singlet decay rates are in agreement with
the predicted PMD for molecules with different orientations. The triplet decay
rate is modified in a fashion correlated to the singlet decay rate. These
results show that PMD engineering can lead to an important suppression of the
fluorescence, introducing a novel aspect of the physical mechanism to enhance
fluorescence intensity in PMD-enhancing systems such as plasmonic devices
Impact of Cognitive Impairment on Functional Outcome in Stroke
The aim of this study was to investigate the effect of the cognitive impairment on functional status in patients with subacute stroke. Fifty-two patients with subacute stroke were included in the study. Mini mental state examination (MMSE) test was used for the evaluation of cognitive status. Patients were separated into two groups according to their cognitive functions. Functional follow-up parameters were activities of daily living (ADL), global recovery and ambulation status. All patients were evaluated on admission to rehabilitation unit, at discharge and 6 months after discharge. Forty-four patients were completed the study. Mean age was 66 and 57 years; disease duration on admission was 4,8 and 3,5 months in the cognitively impaired and normal groups, respectively. Significant improvement was found in terms of functional follow-up parameters in both groups at discharge (P < .05). Functional follow-up parameters did not show statistically significant difference between the groups. But community ambulation rate was higher in cognitively normal group at the sixth month visit. As a result of this study, inpatient rehabilitation was effective both cognitively normal and impaired subacute stroke patients
Asymmetric polarity reversals, bimodal field distribution, and coherence resonance in a spherically symmetric mean-field dynamo model
Using a mean-field dynamo model with a spherically symmetric helical
turbulence parameter alpha which is dynamically quenched and disturbed by
additional noise, the basic features of geomagnetic polarity reversals are
shown to be generic consequences of the dynamo action in the vicinity of
exceptional points of the spectrum. This simple paradigmatic model yields long
periods of constant polarity which are interrupted by self-accelerating field
decays leading to asymmetric polarity reversals. It shows the recently
discovered bimodal field distribution, and it gives a natural explanation of
the correlation between polarity persistence time and field strength. In
addition, we find typical features of coherence resonance in the dependence of
the persistence time on the noise.Comment: 5 pages, 7 figure
Synthesis of 1,3-diynes via detelluration of bis(ethynyl)tellurides
The synthesis of symmetric conjugated diyne systems with electron-withdrawing or electron-donating substituents via a palladium-catalyzed detelluration of bis(arylethynyl)tellurides and bis(alkylethynyl)tellurides is described. This procedure is effected under atmospheric conditions in DMF using Pd(OAc)2 as a catalyst and AgOAc as an additive in the presence of triethylamine. This route offers efficient access to conjugated diyne systems in short reaction time. X-ray crystallographic structure and solid-state conformation of bis(p-tolylethynyl)telluride show a supramolecular chain aligned along the b axis, sustained by C-H...π interactions.Neste artigo é descrita a síntese de sistemas diínicos conjugados contendo substituintes elétronatratores e elétron-doadores via a deteluração catalizada por paládio de bis-(ariletinil)teluretos e bis-(alquiletinil)teluretos. Este procedimento foi realizado sob condições atmosféricas em DMF usando Pd(Oac)2 como catalisador e AgOAc como um aditivo na presença de trietilamina. Esta rota oferece acesso eficiente a sistemas diínicos conjugados em um curto período de tempo. A estrutura cristalográfica por difração de raios X do telureto de bis(p-toluiletinila) e a conformação no estado sólido mostram uma cadeia supramolecular alinhada ao longo do eixo b, sustentada por interações CH...π.FAPESPCNP
5-(4-Fluorophenyl)-2,2,6-trimethyl-4H-1,3-dioxin-4-one
The 1,3-dioxine ring in the title compound, C13H13FO3, is in a half-boat conformation with the methyl-bonded C atom 0.612 (2) Å out of the plane defined by the remaining five atoms
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