2,754 research outputs found
Coherent control of injection currents in high-quality films of Bi2Se3
Films of the topological insulator Bi2Se3 are grown by molecular beam epitaxy
with in-situ reflection high-energy electron diffraction. The films are shown
to be high-quality by X-ray reflectivity and diffraction and atomic-force
microscopy. Quantum interference control of photocurrents is observed by
excitation with harmonically related pulses and detected by terahertz
radiation. The injection current obeys the expected excitation irradiance
dependence, showing linear dependence on the fundamental pulse irradiance and
square-root irradiance dependence of the frequency-doubled optical pulses. The
injection current also follows a sinusoidal relative-phase dependence between
the two excitation pulses. These results confirm the third-order nonlinear
optical origins of the coherently controlled injection current. Experiments are
compared to a tight-binding band structure to illustrate the possible optical
transitions that occur in creating the injection current.Comment: 11 pages, 3 figure, journal articl
The Conditional Lucas & Kanade Algorithm
The Lucas & Kanade (LK) algorithm is the method of choice for efficient dense
image and object alignment. The approach is efficient as it attempts to model
the connection between appearance and geometric displacement through a linear
relationship that assumes independence across pixel coordinates. A drawback of
the approach, however, is its generative nature. Specifically, its performance
is tightly coupled with how well the linear model can synthesize appearance
from geometric displacement, even though the alignment task itself is
associated with the inverse problem. In this paper, we present a new approach,
referred to as the Conditional LK algorithm, which: (i) directly learns linear
models that predict geometric displacement as a function of appearance, and
(ii) employs a novel strategy for ensuring that the generative pixel
independence assumption can still be taken advantage of. We demonstrate that
our approach exhibits superior performance to classical generative forms of the
LK algorithm. Furthermore, we demonstrate its comparable performance to
state-of-the-art methods such as the Supervised Descent Method with
substantially less training examples, as well as the unique ability to "swap"
geometric warp functions without having to retrain from scratch. Finally, from
a theoretical perspective, our approach hints at possible redundancies that
exist in current state-of-the-art methods for alignment that could be leveraged
in vision systems of the future.Comment: 17 pages, 11 figure
Mapping alpha-Particle X-Ray Fluorescence Spectrometer (Map-X)
Many planetary surface processes (like physical and chemical weathering, water activity, diagenesis, low-temperature or impact metamorphism, and biogenic activity) leave traces of their actions as features in the size range 10s to 100s of micron. The Mapping alpha-particle X-ray Spectrometer ("Map-X") is intended to provide chemical imaging at 2 orders of magnitude higher spatial resolution than previously flown instruments, yielding elemental chemistry at or below the scale length where many relict physical, chemical, and biological features can be imaged and interpreted in ancient rocks
Conquering the great divide: Rural mothers of children with chronic health conditions accessing specialist medical care for their children
© 2019 Australian College of Nursing Ltd Background: Globally, the number of children with chronic health conditions (CHCs) is increasing and mothers are mostly responsible for their care. Aim: Few studies have focused on rural mothers and their experiences of sourcing health care for their children who have CHCs. The purpose of this study was to explore these experiences. Method: Using a phenomenological approach, semi-structured interviews were conducted in early 2018. The Consolidated criteria for Reporting Qualitative research (COREQ) guidelines were followed. Sixteen rural mothers were interviewed regarding their experiences of accessing health care to provide optimal management of their children's CHC. Findings: Thematic analysis of resulting data revealed the overarching theme ‘Conquering the great divide’. From this overarching theme, four themes emerged. This paper focuses on the first theme, ‘Heading to the big smoke: access’. Discussion: Rural mothers felt challenged accessing health care for their children in the major cities whilst also maintaining routine family life back home. Conclusion: Understanding these rural women's experiences could assist health care professionals to develop strategies to facilitate rural mothers accessing services for their children with a CHC
Clinical spirocercosis in a dog in the UK
A 2-year-old female neutered crossbreed dog was presented for evaluation of a 3-day history of haematemesis, melaena and hyporexia. The dog had been imported from a rescue centre in Hungary 4 months prior to presentation. Abdominal CT revealed the presence of a 3 cm×3 cm×4 cm diameter heterogenous intraluminal mass lesion in the gastric cardia, surrounding the ostium of the cardia and continuous with the distal oesophagus. The mass lesion was subsequently surgically resected. Histopathology of the gastric mass lesion was consistent with a Spirocerca lupi granuloma. The patient unfortunately developed a pyothorax and suffered cardiopulmonary arrest resulting in death 2 days postoperatively. To the authors’ knowledge, this is the first reported case of clinical spirocercosis reported in a dog in the UK
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