We propose a fast calculation method to extract feature covariance matrix of cuboid of arbitrary size and arbitrary location within a given video. Every pixel in a video has several features, such as coordinates, color, gray value, gradients and orientation. Feature covariance matrix can be used to describe a video cuboid. By taking advantage of the spatio-temporal arrangement of pixels using integral video, any cuboid sum can be computed in constant time. We follow a similar idea for fast calculation of cuboid's covariance matrices. We construct integral videos for all separate features as well as integral videos of the multiplication of any two feature combinations. Using this set of integral videos we can expedite the search process more than hundreds of times in comparison to the existing conventional approach.
We studied the temperature-dependent steady-state and time-resolved fluorescence properties of very small (1-2 nm) ZnO, CdO, and PbO amorphous nanoclusters prepared in AOT reverse micelles and imbedded in polymethyl methacrylate(PMMA) films. X-ray diffraction and electron diffraction and imaging indicate that these structures are amorphous. These amorphous oxide nanoclusters demonstrate similar structural, electronic, and optical properties. Properties of steady-state fluorescence spectra indicate the unique localization of electronic states due to the amorphous structure. ZnO and CdO show double-band fluorescence structure, which is due to the spin-orbital splitting, similar to Cu2O. Time-resolved fluorescence studies of the nanoclusters in the polymer reveal two lifetime components, as found in solution. The slow component reflects relaxation processes from band-tail states while the fast component may be related to high-lying extended states. The temperature dependence of fast fluorescence component reveals the presence of exciton hopping between anharmonic wells at temperatures higher than 200K. We correlate the barrier height between two wells formed around local atoms with the inter-atomic distance and bond ionicity.
Wurtzite‐structured III‐group nitrides, like GaN, InN, AlN, and their alloys, present both piezoelectric and semiconducting properties under straining owing to the polarization of ions in a crystal with non‐central symmetry. The piezoelectric polarization charges are created at the interface when a strain is applied. As a result, a piezoelectric potential (piezopotential) is produced, which is used as a “gate” to tune/control the charge transport behavior across a metal/semiconductor interface or a p‐n junction. This is called as piezotronic effect. A series of piezotronic devices and applications have been developed, such as piezotronic nanogenerators (NGs), piezotronic transistors, piezotronic logic devices, piezotronic electromechanical memories, piezotronic enhanced biochemical, and gas sensors and so on. With the flourished development of piezotronic effect, the piezo‐phototronic effect, as the three‐way coupling of piezoelectric polarization, semiconductor properties, and optical excitation, utilizes the piezopotential to modulate the energy band profile and control the carrier generation, transportation, separation, and/or recombination for improving performances of optoelectronic devices. This paper intends to provide an overview of the rapid progress in the emerging fields of piezotronics and piezo‐phototronics, covering from the fundamental principles to devices and applications. This study will provide important insight into the potential applications of GaN based electronic/optoelectronic devices in sensing, active flexible/stretchable electronics/optoelectronics, energy harvesting, human‐machine interfacing, biomedical diagnosis/therapy, and prosthetics.
Background: The early identification of recipients at high risk of graft loss is clinically relevant after kidney transplantation. The authors explored whether the earlier monitoring of tacrolimus (Tac) time-in-therapeutic range (TTR) is predictive of and a subsequent gain in TTR improves transplant outcomes. Methods: The TTR within 3, 6, 9, and 12 months was evaluated. Multivariate Cox analyses were performed to explore when TTR was predictive of transplant outcomes. Patients were divided into 3 groups based on incremental TTR change [TTR gain (increase >10%), TTR stable (maintained within 10%), and TTR loss (decrease >10%)] and 4 groups based on predefined cutoff values [low–low (LL), low–high (LH), high–low (HL), and high–high (HH)] using 6- and 12-month TTRs. Death-censored graft loss and patient death were primary outcomes. Results: Nonlinear associations were observed between 6-, 9-, and 12-month TTR and death-censored graft and patient survival rates. In multivariate analysis, every 10% increase in 6-, 9-, and 12-month TTRs was associated with reduced patient death [hazard ratio (HR): 0.83; HR: 0.68; HR: 0.61, respectively] and graft loss (HR: 0.88; HR: 0.73; HR: 0.66, respectively). A nonlinear relationship was observed between transplant outcomes and incremental changes in TTR. TTR gain and stable TTR contributed to higher graft survival (HR: 0.20; HR: 0.21) and patient survival (HR: 0.14; HR: 0.15) rates than TTR loss, whereas the former 2 had comparable outcomes. Furthermore, compared with those in the HH group, the LL and HL groups had inferior graft survival (HR: 3.33; HR: 5.17) and patient survival (HR: 5.15; HR: 8.94) rates, whereas the LH group had similar outcomes ( P = 0.63, P = 0.97). Nonadherence was the main controllable risk factor for low TTR. Conclusions: The 6-month TTR identified patients at higher risk of worse outcomes. The subsequent gain of TTR may contribute to better transplant outcomes.
Abstract Abstract A dynamical theory is proposed to calculate the diffraction patterns of electrons which have undergone thermal diffuse scattering (TDS). The lattice dynamics and electron diffraction dynamics are comprehensively combined in this approach. Full dynamical simulations are presented for Mo(001). Under the single-inelastic-scattering approximation and in the near-zone-axis case, the sharpness of the TDS streaks is determined by the phonon dispersion relationships of the acoustic branches, the optical branches contribute only a diffuse background, and dynamical scattering effects can change the intensity distribution of TDS electrons but have almost no effect on the sharpness of TDS streaks. The TDS streaks are defined by the qx-qy curves which satisfy δi(q)=O, where δi(q) is the phonon dispersion relationship determined by the two-dimensional atomic vibrations in the (hkl) plane perpendicular to the incident beam direction B = [hkl]. The directions of TDS streaks predicted according to these procedures are consistent with those predicted according to the q·[r(1)-r(l1) = 0 rule given by Wang and Bentley, where the summation of l1, is restricted to the first-nearest neighbours of the lth atom that are located in the same atomic plane as the lth atom perpendicular to the incidence beam direction. Atomic resolution images can be formed by TDS electrons in transmission electron microscopy. The image theory is equivalent to the incoherent imaging theory if the spherical aberration coefficient C8 for the objective lens is small. The image resolution may be higher than that formed by pure elastically scattered electrons, but the 'inclined-incidence effect' (i.e. the correction of momentum transfer q to the electron wave-vector K) in phonon scattering may distort the image. The phase coupling of vibrating atoms does not affect calculations for images but does affect diffraction patterns. Thus the image simulation can be performed based on the Einstein model as long as the correct vibration amplitude for each atom is used. Equivalent results are obtained for the TDS electrons based on either the quantum inelastic scattering theory or the 'frozen'-lattice model of the semiclassical approach if the temperature is not much higher than room temperature.
Electron beam chemical vapor deposition was performed in a modified environmental scanning electron microscope to deposit platinum structures. Process variables including voltage, beam current, deposition time, dwell time, and line time were studied in statistically designed and analyzed experiments on fiber (pillar-like structures) and line (wall-like structures) deposition. Deposition rates and geometric features such as aspect ratio were optimized. Results from the experimentation showed the importance of the beam current, voltage, and adsorbate replenishment to the deposition process. Growth rates up to 0.9μm∕min were obtained for short deposition times.
