1,351 research outputs found
Microwave characteristics of liquid-crystal tunable capacitors
[[abstract]]This letter investigates the microwave characteristics of the liquid crystal tunable capacitors for the first time. With the dielectric anisotropy properties, the liquid crystal capacitors present very different characteristics compared to the semiconductor or MEMS tunable capacitors. A quality factor of 310 with a control voltage of 5 V was achieved at 4 GHz. A tuning range of 25.3% for the control voltages from 0 to 5 V was obtained at 5 GHz. The results demonstrate the potential applications of liquid crystals as dielectric materials for capacitors with high quality factors and wide tuning ranges at high frequencies, particularly suitable for the future flexible electronics with transparent substrates.[[fileno]]2030121010007[[department]]電機工程學
Diffuse liver disease classification from ultrasound surface characterization, clinical and laboratorial data
In this work liver contour is semi-automatically segmented and quantified in order to help the identification and diagnosis of diffuse liver disease. The features extracted from the liver contour are jointly used with clinical and laboratorial data in the staging process. The classification results of a support vector machine, a Bayesian and a k-nearest
neighbor classifier are compared. A population of 88 patients at five different
stages of diffuse liver disease and a leave-one-out cross-validation strategy are used in the classification process. The best results are obtained using the k-nearest neighbor classifier, with an overall accuracy of 80.68%. The good performance of the proposed method shows a reliable
indicator that can improve the information in the staging of diffuse liver disease
Magnetotransport near a quantum critical point in a simple metal
We use geometric considerations to study transport properties, such as the
conductivity and Hall coefficient, near the onset of a nesting-driven spin
density wave in a simple metal. In particular, motivated by recent experiments
on vanadium-doped chromium, we study the variation of transport coefficients
with the onset of magnetism within a mean-field treatment of a model that
contains nearly nested electron and hole Fermi surfaces. We show that most
transport coefficients display a leading dependence that is linear in the
energy gap. The coefficient of the linear term, though, can be small. In
particular, we find that the Hall conductivity is essentially
unchanged, due to electron-hole compensation, as the system goes through the
quantum critical point. This conclusion extends a similar observation we made
earlier for the case of completely flat Fermi surfaces to the immediate
vicinity of the quantum critical point where nesting is present but not
perfect.Comment: 11 pages revtex, 4 figure
Usability Challenges in Smartphone Web Access: A Systematic Literature Review
Part 8: International Workshop on Information Engineering and ManagementInternational audienceSystematic literature reviews facilitate methodical understanding of current advances in a field. With the increasing popularity of smartphones, they have become an important means to access the web. Although the literature on this topic is growing in recent times, there has been no effort yet to systematically review it. This paper reports on a systematic literature review of primary studies from 2007 to 2012 that concern mobile web usability. We identify the usability dimensions tested and the testing procedures adopted in the literature. We anticipate that our work will not only help researchers understand the current state of usability testing of mobile web but also identify the areas where further research is needed in addressing the challenges identified
Kinetic energy driven superconductivity in doped cuprates
Within the t-J model, the mechanism of superconductivity in doped cuprates is
studied based on the partial charge-spin separation fermion-spin theory. It is
shown that dressed holons interact occurring directly through the kinetic
energy by exchanging dressed spinon excitations, leading to a net attractive
force between dressed holons, then the electron Cooper pairs originating from
the dressed holon pairing state are due to the charge-spin recombination, and
their condensation reveals the superconducting ground-state. The electron
superconducting transition temperature is determined by the dressed holon pair
transition temperature, and is proportional to the concentration of doped holes
in the underdoped regime. With the common form of the electron Cooper pair, we
also show that there is a coexistence of the electron Cooper pair and
antiferromagnetic short-range correlation, and hence the antiferromagnetic
short-range fluctuation can persist into the superconducting state. Our results
are qualitatively consistent with experiments.Comment: 6 pages, Revtex, two figures are included, corrected typo
Canadian paediatric neurology workforce survey and consensus statement
Background: Little knowledge exists on the availability of academic and community paediatric neurology positions. This knowledge is crucial for making workforce decisions. Our study aimed to: 1) obtain information regarding the availability of positions for paediatric neurologists in academic centres; 2) survey paediatric neurology trainees regarding their perceptions of employment issues and career plans; 3) survey practicing community paediatric neurologists 4) convene a group of paediatric neurologists to develop consensus regarding how to address these workforce issues. Methods: Surveys addressing workforce issues regarding paediatric neurology in Canada were sent to: 1) all paediatric neurology program directors in Canada (n=9) who then solicited information from division heads and from paediatric neurologists in surrounding areas; 2) paediatric neurology trainees in Canada (n=57) and; 3) community paediatric neurologists (n=27). A meeting was held with relevant stakeholders to develop a consensus on how to approach employment issues. Results: The response rate was 100% from program directors, 57.9% from residents and 44% from community paediatric neurologists. We found that the number of projected positions in academic paediatric neurology is fewer than the number of paediatric neurologists that are being trained over the next five to ten years, despite a clinical need for paediatric neurologists. Paediatric neurology residents are concerned about job availability and desire more career counselling. Conclusions: There is a current and projected clinical demand for paediatric neurologists despite a lack of academic positions. Training programs should focus on community neurology as a viable career option
Local fluctuations in quantum critical metals
We show that spatially local, yet low-energy, fluctuations can play an
essential role in the physics of strongly correlated electron systems tuned to
a quantum critical point. A detailed microscopic analysis of the Kondo lattice
model is carried out within an extended dynamical mean-field approach. The
correlation functions for the lattice model are calculated through a
self-consistent Bose-Fermi Kondo problem, in which a local moment is coupled
both to a fermionic bath and to a bosonic bath (a fluctuating magnetic field).
A renormalization-group treatment of this impurity problem--perturbative in
, where is an exponent characterizing the spectrum
of the bosonic bath--shows that competition between the two couplings can drive
the local-moment fluctuations critical. As a result, two distinct types of
quantum critical point emerge in the Kondo lattice, one being of the usual
spin-density-wave type, the other ``locally critical.'' Near the locally
critical point, the dynamical spin susceptibility exhibits scaling
with a fractional exponent. While the spin-density-wave critical point is
Gaussian, the locally critical point is an interacting fixed point at which
long-wavelength and spatially local critical modes coexist. A Ginzburg-Landau
description for the locally critical point is discussed. It is argued that
these results are robust, that local criticality provides a natural description
of the quantum critical behavior seen in a number of heavy-fermion metals, and
that this picture may also be relevant to other strongly correlated metals.Comment: 20 pages, 12 figures; typos in figure 3 and in the main text
corrected, version as publishe
Doping dependence of the gap anisotropy in LCCO studied by millimeter-wave spectroscopy
We measure the penetration depth of optimally doped and underdoped
La2-xCexCuO4 in the millimeter frequency domain (4 - 7 cm-1) and for
temperatures 2 K < T < 300 K. The penetration depth as function of temperature
reveals significant changes on electron doping. It shows quadratic temperature
dependence in underdoped samples, but increases almost exponentially at optimal
doping. Significant changes in the gap anisotropy (or even in the gap symmetry)
may account for this transition.Comment: 4 pages, 4 figure
‘Cytology-on-a-chip’ based sensors for monitoring of potentially malignant oral lesions
Despite significant advances in surgical procedures and treatment, long-term prognosis for patients with oral cancer remains poor, with survival rates among the lowest of major cancers. Better methods are desperately needed to identify potential malignancies early when treatments are more effective. Objective To develop robust classification models from cytology-on-a-chip measurements that mirror diagnostic performance of gold standard approach involving tissue biopsy. Materials and methods Measurements were recorded from 714 prospectively recruited patients with suspicious lesions across 6 diagnostic categories (each confirmed by tissue biopsy -histopathology) using a powerful new ‘cytology-on-a-chip’ approach capable of executing high content analysis at a single cell level. Over 200 cellular features related to biomarker expression, nuclear parameters and cellular morphology were recorded per cell. By cataloging an average of 2000 cells per patient, these efforts resulted in nearly 13 million indexed objects. Results Binary “low-risk”/“high-risk” models yielded AUC values of 0.88 and 0.84 for training and validation models, respectively, with an accompanying difference in sensitivity + specificity of 6.2%. In terms of accuracy, this model accurately predicted the correct diagnosis approximately 70% of the time, compared to the 69% initial agreement rate of the pool of expert pathologists. Key parameters identified in these models included cell circularity, Ki67 and EGFR expression, nuclear-cytoplasmic ratio, nuclear area, and cell area. Conclusions This chip-based approach yields objective data that can be leveraged for diagnosis and management of patients with PMOL as well as uncovering new molecular-level insights behind cytological differences across the OED spectrum
Measurement of W Polarisation at LEP
The three different helicity states of W bosons produced in the reaction e+
e- -> W+ W- -> l nu q q~ at LEP are studied using leptonic and hadronic W
decays. Data at centre-of-mass energies \sqrt s = 183-209 GeV are used to
measure the polarisation of W bosons, and its dependence on the W boson
production angle. The fraction of longitudinally polarised W bosons is measured
to be 0.218 \pm 0.027 \pm 0.016 where the first uncertainty is statistical and
the second systematic, in agreement with the Standard Model expectation
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