243 research outputs found
Electric field effects on spin accumulation in Nb-doped SrTiO3 using tunable spin injection contacts at room temperature
We report on features in charge transport and spin injection in an oxide semiconductor, Nb-doped SrTiO3. This is demonstrated using electrically tunable spin injection contacts which exploit the large electric field at the interface and its interplay with the relative permittivity of the semiconductor. We realize spin accumulation in Nb-doped SrTiO3 which displays a unique dependence of the spin lifetime with bias polarity. These findings suggest a strong influence of the interface electric field on the charge transport as well as on spin accumulation unlike in conventional semiconductors and opens up promising avenues in oxide spintronics
Efficient and feasible state tomography of quantum many-body systems
We present a novel method to perform quantum state tomography for
many-particle systems which are particularly suitable for estimating states in
lattice systems such as of ultra-cold atoms in optical lattices. We show that
the need for measuring a tomographically complete set of observables can be
overcome by letting the state evolve under some suitably chosen random circuits
followed by the measurement of a single observable. We generalize known results
about the approximation of unitary 2-designs, i.e., certain classes of random
unitary matrices, by random quantum circuits and connect our findings to the
theory of quantum compressed sensing. We show that for ultra-cold atoms in
optical lattices established techniques like optical super-lattices, laser
speckles, and time-of-flight measurements are sufficient to perform fully
certified, assumption-free tomography. Combining our approach with tensor
network methods - in particular the theory of matrix-product states - we
identify situations where the effort of reconstruction is even constant in the
number of lattice sites, allowing in principle to perform tomography on
large-scale systems readily available in present experiments.Comment: 10 pages, 3 figures, minor corrections, discussion added, emphasizing
that no single-site addressing is needed at any stage of the scheme when
implemented in optical lattice system
Image Tracking Study on Courtship Behavior of Drosophila
Background: In recent years, there have been extensive studies aimed at decoding the DNA. Identifying the genetic cause of specific changes in a simple organism like Drosophila may help scientists recognize how multiple gene interactions may make some people more susceptible to heart disease or cancer. Investigators have devised experiments to observe changes in the gene networks in mutant Drosophila that responds differently to light, or have lower or higher locomotor activity. However, these studies focused on the behavior of the individual fly or on pair-wise interactions in the study of aggression or courtship. The behavior of these activities has been captured on film and inspected by a well-trained researcher after repeatedly watching the recorded film. Some studies also focused on ways to reduce the inspection time and increase the accuracy of the behavior experiment. Methodology: In this study, the behavior of drosophila during courtship was analyzed automatically by machine vision. We investigated the position and behavior discrimination during courtship using the captured images. Identification of the characteristics of drosophila, including sex, size, heading direction, and wing angles, can be computed using image analysis techniques that employ the Gaussian mixture model. The behavior of multiple drosophilae can also be analyzed simultaneously using the motion-prediction model and the variation constraint of heading direction. Conclusions: The overlapped fruit flies can be identified based on the relationship between body centers. Moreover, th
Optical properties of MgH2 measured in situ in a novel gas cell for ellipsometry/spectrophotometry
The dielectric properties of alpha-MgH2 are investigated in the photon energy
range between 1 and 6.5 eV. For this purpose, a novel sample configuration and
experimental setup are developed that allow both optical transmission and
ellipsometric measurements of a transparent thin film in equilibrium with
hydrogen. We show that alpha-MgH2 is a transparent, colour neutral insulator
with a band gap of 5.6 +/- 0.1 eV. It has an intrinsic transparency of about
80% over the whole visible spectrum. The dielectric function found in this work
confirms very recent band structure calculations using the GW approximation by
Alford and Chou [J.A. Alford and M.Y. Chou (unpublished)]. As Pd is used as a
cap layer we report also the optical properties of PdHx thin films.Comment: REVTeX4, 15 pages, 12 figures, 5 table
Stromal-epithelial interaction induces GALNT14 in prostate carcinoma cells
IntroductionCell-cell communication is an important process in healthy tissue but also gains enhanced attention regarding pathological tissue. To date, the tumor microenvironment is gradually brought into focus when studying tumorigenesis. In the prostate gland, stromal and epithelial cells greatly interact to maintain homeostasis or tissue integrity. This study focuses on an indirect communication via soluble factors.MethodsTo investigate the cell-cell interaction via soluble factors, the prostate carcinoma cell line LNCaP and the stromal primary cells p21 were co-cultured without direct contact and RNA was isolated at defined time points. Differences in gene expression were finally analyzed by RNA sequencing.ResultsRNA sequencing revealed a time-depending differential expression profile. Selected factors were subsequently characterized at molecular level and analyzed in human prostate tissue of different developmental stages as well as pathology. GALNT14 was one of the highest induced co-culture-specific genes in LNCaP cells. Detection in healthy tissue and BPH revealed an age-dependent decrease in GALNT14 expression. Moreover, in prostate carcinoma, GALNT14 expression heavily varied independent of the Gleason score.ConclusionOverall, this work provides a basis for further studies related to paracrine stromal-epithelial interaction in prostate carcinoma and highlights the importance of GALNT14
Automated Home-Cage Behavioural Phenotyping of Mice
Neurobehavioral analysis of mouse phenotypes requires the monitoring of mouse behavior over long
periods of time. Here, we describe a trainable computer vision system enabling the automated analysis
of complex mouse behaviors. We provide software and an extensive manually annotated video
database used for training and testing the system. Our system performs on par with human scoring, as
measured from ground-truth manual annotations of thousands of clips of freely behaving mice. As a
validation of the system, we characterized the home-cage behaviors of two standard inbred and two
non-standard mouse strains. From this data we were able to predict in a blind test the strain identity of
individual animals with high accuracy. Our video-based software will complement existing sensor
based automated approaches and enable an adaptable, comprehensive, high-throughput, fine-grained,
automated analysis of mouse behavior.McGovern Institute for Brain ResearchCalifornia Institute of Technology. Broad Fellows Program in Brain CircuitryNational Science Council (China) (TMS-094-1-A032
Electromechanical finite element modelling for dynamic analysis of a cantilevered piezoelectric energy harvester with tip mass offset under base excitations
A new electromechanical finite element modelling of a vibration power harvester and its validation with experimental studies are presented in this paper. The new contributions for modelling the electromechanical finite element piezoelectric unimorph beam with tip mass offset under base excitation encompass five major solution techniques. These include the electromechanical discretization, kinematic equations, coupled field equations, Lagrangian electromechanical dynamic equations, and orthonormalised global matrix and scalar forms of electromechanical finite element dynamic equations. Such techniques have not been rigorously modelled previously by other researchers. There are also benefits to presenting the numerical techniques proposed in this paper. First, the proposed numerical techniques can be used for Q1 applications in many different geometrical models, including MEMS power harvesting devices. Second, applying tip mass offset located after the end of the piezoelectric beam length can result in a very practical design, which avoids direct contact with piezoelectric material because of its brittle nature.Since the surfaces of actual piezoelectric material are covered evenly with thin conducting electrodes for generating single voltage, we introduce the new electromechanical discretization, consisting of the mechanical and electrical discretised elements. Moreover, the reduced electromechanical finite element dynamic equations can be further formulated to obtain the series form of new multimode electromechanical frequency response functions (FRFs) of the displacement, velocity, voltage, current, and power, including optimal power harvesting. The normalized numerical strain node and eigenmode shapes are also further formulated using numerical discretization. Finally, the parametric numerical case studies of the piezoelectric unimorph beam under a resistive shunt circuit show good agreement with the experimental studies
Optimizing quantum process tomography with unitary 2-designs
We show that weighted unitary 2-designs define optimal measurements on the
system-ancilla output state for ancilla-assisted process tomography of unital
quantum channels. Examples include complete sets of mutually unbiased
unitary-operator bases. Each of these specifies a minimal series of optimal
orthogonal measurements. General quantum channels are also considered.Comment: 28 page
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