Biomedical image time series registration with particle filtering (Parçacık süzgeci ile biyomedikal görüntü zaman serisi çakıştırma)

We propose a family of methods for biomedical image time series registration based on Particle filtering. The first method applies an intensity-based information-theoretic approach to calculate importance weights. An effective second group of methods use landmark-based approaches for the same purpose by automatically detecting intensity maxima or SIFT interest points from image time series. A brute-force search for the best alignment usually produces good results with proper cost functions, but becomes computationally expensive if the whole search space is explored. Hill climbing optimizations seek local optima. Particle filtering avoids local solutions by introducing randomness and sequentially updating the posterior distribution representing probable solutions. Thus, it can be more robust for the registration of image time series. We show promising preliminary results on dendrite image time series

Approximative distance computation by random hashing

We propose an approximate computation technique for inter-object distances of binary data sets. Our approach is based on locality sensitive hashing. We randomly select a number of projections of the data set and group objects into buckets based on the hash values of these projections. For each pair of objects, occurrences in the same bucket are counted and the exact Hamming distance is approximated based on the number of co-occurrences in all buckets. We parallelize the computation using mainly two schemes. The first assigns each random subspace to a processor for calculating the local co-occurrence matrix, where all the local co-occurrence matrices are combined into the final co-occurrence matrix. The second method provides the same distance approximation in longer runtimes by limiting the total message size in a parallel computing environment, which is especially useful for very large data sets generating immense message traffic. Our methods produce very accurate results, scale up well with the number of objects, and tolerate processor failures. Experimental evaluations on supercomputers and workstations with several processors demonstrate the usefulness of our methods

Impact of liver transplantation on rate-corrected QT interval and myocardial function in children with chronic liver disease

WOS: 000264891700008PubMed ID: 18537904Prolonged QTc interval (> 440 ms) is a common abnormality in adult patients with CLD and has been reported to predict patient survival. In this study, 88 children who underwent evaluation for LT, including a 12-lead electrocardiogram and echocardiogram included to determine the frequency of QTc prolongation and related factors in children with CLD and the effect of LT on these factors. Sixty-nine healthy, age- and sex-matched children served as controls. QTc interval was prolonged in 40 CLD patients (45.4%). It was found to be related to PELD score and presence of portal hypertension. Mean QTc was higher in patients who died prior to LT than in the survivors without LT. Mortality risk was increased 3.66-fold in patients with prolonged QTc (p = 0.001, 95% CI: 2-7.2). Cox regression analysis showed that only PELD score was an independent predictor of survival (p = 0.001, beta = -0.41, 95% CI: 5.58-1.82). Five of 48 transplanted children died within three months post-transplant; QTc was not related to post-transplant survival (p = 0.27). QTc normalized in 63.8% patients after LT. After LT, LAD, LVEF, and LVPWT decreased. In conclusion, QTc prolongation is common in children with CLD and associated with high mortality. It may be useful for assessment of the severity of CLD and for the timing for transplantation

Excited state dynamics of nanocrystalline VO2 with white light continuum time resolved spectroscopy

In an attempt to use ultrafast pump probe spectroscopy technique with white light continuum to reveal wavelength dependent dynamics of VO2, bandgap needs to be opened. Therefore, nanostructured amorphous and crystalline VO2 thin films were prepared with pulsed DC magnetron reactive sputtering. The mean diameters of grains were measured as 22 +/- 0.1 nm and 44 +/- 0.1 nm for amorphous and crystalline VO2 thin films, respectively. Temperature dependent resistance measurements show that nanocrystalline VO2 thin film exhibit metal insulator phase transition. The films exhibited dual band gaps (2.3 eV, AbstractIn an attempt to use ultrafast pump probe spectroscopy technique with white light continuum to reveal wavelength dependent dynamics of VO2, bandgap needs to be opened. Therefore, nanostructured amorphous and crystalline VO2&nbsp;thin films were prepared with pulsed DC magnetron reactive sputtering. The mean diameters of grains were measured as 22&plusmn;0.1&nbsp;nm and 44&plusmn;0.1&nbsp;nm for amorphous and crystalline VO2&nbsp;thin films, respectively. Temperature dependent resistance measurements show that nanocrystalline VO2&nbsp;thin film exhibit metal insulator phase transition. The films exhibited dual band gaps (2.3&nbsp;eV, &lt;0.6&nbsp;eV for amorphous films and 1.3&nbsp;eV, 1.8&nbsp;eV for crystalline film). Increased band gaps made it possible to perform time resolved transmission and reflection experiments with white light continuum at fluences above and below photo induced phase transition threshold. Although transmission chance due to photo induced phase transition of VO2&nbsp;in the literature usually takes places at infrared region of the spectrum, transmission chance was observed in visible as low as 630&nbsp;nm in broadband probe spectra. It was observed that measured time scales depend on not only pump fluence but also probe wavelength. Experiments gave the evidence of the long-lived lower energy non-equilibrium state related to the photo induced phase.</p

Efficient sensing of single viruses and nanoparticles by nanomechanical sensors integrated with ion lenses

Nanoelectromechanical Systems (NEMS) resonators can be used to detect, weigh and identify single nanoparticles and viruses. Given their small footprint, however, NEMS are plagued by low analyte detection rate since the active sensing cross-sections to capture analyte particles is very small. Here we report on the development of an on-chip focusing lens operating in air and integrated with the NEMS sensor. The integrated system increases the capture efficiency by orders of magnitude, and allows for operation under ambient conditions to measure the mass of nanoparticles and virions. With this system, mass spectrum of nanoparticle samples and mammalian viruses at biologically relevant concentrations can be characterized within less than 30 minutes