Numerical Simulation of Nano Scanning in Intermittent-Contact Mode AFM under Q control

We investigate nano scanning in tapping mode atomic force microscopy (AFM) under quality (Q) control via numerical simulations performed in SIMULINK. We focus on the simulation of whole scan process rather than the simulation of cantilever dynamics and the force interactions between the probe tip and the surface alone, as in most of the earlier numerical studies. This enables us to quantify the scan performance under Q control for different scan settings. Using the numerical simulations, we first investigate the effect of elastic modulus of sample (relative to the substrate surface) and probe stiffness on the scan results. Our numerical simulations show that scanning in attractive regime using soft cantilevers with high Qeff results in a better image quality. We, then demonstrate the trade-off in setting the effective Q factor (Qeff) of the probe in Q control: low values of Qeff cause an increase in tapping forces while higher ones limit the maximum achievable scan speed due to the slow response of the cantilever to the rapid changes in surface profile. Finally, we show that it is possible to achieve higher scan speeds without causing an increase in the tapping forces using adaptive Q control (AQC), in which the Q factor of the probe is changed instantaneously depending on the magnitude of the error signal in oscillation amplitude. The scan performance of AQC is quantitatively compared to that of standard Q control using iso-error curves obtained from numerical simulations first and then the results are validated through scan experiments performed using a physical set-up

Scan speed control for tapping mode SPM

In order to increase the imaging speed of a scanning probe microscope in tapping mode, we propose to use a dynamic controller on 'parachuting' regions. Furthermore, we propose to use variable scan speed on 'upward step' regions, with the speed determined by the error signal of the closed-loop control. We offer line traces obtained on a calibration grating with 25-nm step height, using both standard scanning and our scanning method, as experimental evidence

Dexmedetomidine or Propofol for Sedation in Mechanically Ventilated Adults with Sepsis

BACKGROUND: Guidelines currently recommend targeting light sedation with dexmedetomidine or propofol for adults receiving mechanical ventilation. Differences exist between these sedatives in arousability, immunity, and inflammation. Whether they affect outcomes differentially in mechanically ventilated adults with sepsis undergoing light sedation is unknown. METHODS: In a multicenter, double-blind trial, we randomly assigned mechanically ventilated adults with sepsis to receive dexmedetomidine (0.2 to 1.5 μg per kilogram of body weight per hour) or propofol (5 to 50 μg per kilogram per minute), with doses adjusted by bedside nurses to achieve target sedation goals set by clinicians according to the Richmond Agitation-Sedation Scale (RASS, on which scores range from -5 [unresponsive] to +4 [combative]). The primary end point was days alive without delirium or coma during the 14-day intervention period. Secondary end points were ventilator-free days at 28 days, death at 90 days, and age-adjusted total score on the Telephone Interview for Cognitive Status questionnaire (TICS-T; scores range from 0 to 100, with a mean of 50±10 and lower scores indicating worse cognition) at 6 months. RESULTS: Of 432 patients who underwent randomization, 422 were assigned to receive a trial drug and were included in the analyses - 214 patients received dexmedetomidine at a median dose of 0.27 μg per kilogram per hour, and 208 received propofol at a median dose of 10.21 μg per kilogram per minute. The median duration of receipt of the trial drugs was 3.0 days (interquartile range, 2.0 to 6.0), and the median RASS score was -2.0 (interquartile range, -3.0 to -1.0). We found no difference between dexmedetomidine and propofol in the number of days alive without delirium or coma (adjusted median, 10.7 vs. 10.8 days; odds ratio, 0.96; 95% confidence interval [CI], 0.74 to 1.26), ventilator-free days (adjusted median, 23.7 vs. 24.0 days; odds ratio, 0.98; 95% CI, 0.63 to 1.51), death at 90 days (38% vs. 39%; hazard ratio, 1.06; 95% CI, 0.74 to 1.52), or TICS-T score at 6 months (adjusted median score, 40.9 vs. 41.4; odds ratio, 0.94; 95% CI, 0.66 to 1.33). Safety end points were similar in the two groups. CONCLUSIONS: Among mechanically ventilated adults with sepsis who were being treated with recommended light-sedation approaches, outcomes in patients who received dexmedetomidine did not differ from outcomes in those who received propofol. (Funded by the National Institutes of Health; ClinicalTrials.gov number, NCT01739933.

Aplicação do movimento kepleriano na orientação de imagens HRC - CBERS 2b

Nos últimos 20 anos, pesquisas voltadas ao desenvolvimento de modelos rigorosos para a orientação de sensores orbitais puhbroom lineares vêm sendo desenvolvidas e apresentadas. Na maioria destas pesquisas, a trajetória e a orientação do satélite durante a formação das cenas são obtidas a partir de polinômios de 1º, 2º e até 3º grau. Porém, a atribuição de significado físico aos coeficientes polinomiais indica que o primeiro e o segundo termo se referem à velocidade e a aceleração da plataforma no instante referente à aquisição da primeira linha da cena. Estas quantidades podem ser associadas ao Problema dos Dois Corpos, sendo desenvolvido de acordo com a equação do Movimento Uniformemente Variado. O modelo resultante deste desenvolvimento foi denominado por Michalis e Dowman como Modelo de Kepler. Nesta pesquisa, o Modelo de Kepler é aplicado na orientação de imagens HRC/CBERS 2B e comparado com os modelos que utilizam polinômios para a propagação dos Parâmetros de orientação exterior (POE), amplamente utilizados atualmente. Os resultados obtidos ao comparar o Modelo de Kepler e os modelos polinomiais indicaram que o uso do primeiro modelo permitiu a obtenção de melhores resultados em relação ao segundo