1,184 research outputs found
Oxidation of Nickel in AlCl3-1-Butylpyridinium Chloride at Ambient Temperature
We have studied in detail the electrochemical reaction of nickel in several kinds of molar ratio-controlled molten salts consisting of AlCl(3) and 1-butylpyridinium chloride (BPC) at 40°C. We observed NiCl(2) as an oxidation product from nickel on the surface of the electrode in slightly acidic AlCl(3)/BPC salts with molar ratios of 1.05/1.0 and 1.1/1.0. However, in strongly acidic salt with the ratio of 1.5/1.0, NiCl(2) deposits on the electrode less than when in the above salts, and no NiCl(29) is observed in basic and neutral salts with the ratio of 1.0/1.0 or less AlCl(3) content. This suggests that [NiCl(4)](2−) ions form as the oxidation of nickel in such neutral and basic AlC(3)/BPC (salts)
(Pseudo) Random Quantum States with Binary Phase
We prove a quantum information-theoretic conjecture due to Ji, Liu and Song
(CRYPTO 2018) which suggested that a uniform superposition with random
\emph{binary} phase is statistically indistinguishable from a Haar random
state. That is, any polynomial number of copies of the aforementioned state is
within exponentially small trace distance from the same number of copies of a
Haar random state.
As a consequence, we get a provable elementary construction of
\emph{pseudorandom} quantum states from post-quantum pseudorandom functions.
Generating pseduorandom quantum states is desirable for physical applications
as well as for computational tasks such as quantum money. We observe that
replacing the pseudorandom function with a -wise independent function
(either in our construction or in previous work), results in an explicit
construction for \emph{quantum state -designs} for all . In fact, we show
that the circuit complexity (in terms of both circuit size and depth) of
constructing -designs is bounded by that of -wise independent
functions. Explicitly, while in prior literature -designs required linear
depth (for ), this observation shows that polylogarithmic depth suffices
for all .
We note that our constructions yield pseudorandom states and state designs
with only real-valued amplitudes, which was not previously known. Furthermore,
generating these states require quantum circuit of restricted form: applying
one layer of Hadamard gates, followed by a sequence of Toffoli gates. This
structure may be useful for efficiency and simplicity of implementation
Single-dot spectroscopy via elastic single-electron tunneling through a pair of coupled quantum dots
We study the electronic structure of a single self-assembled InAs quantum dot
by probing elastic single-electron tunneling through a single pair of weakly
coupled dots. In the region below pinch-off voltage, the non-linear threshold
voltage behavior provides electronic addition energies exactly as the linear,
Coulomb blockade oscillation does. By analyzing it, we identify the s and p
shell addition spectrum for up to six electrons in the single InAs dot, i.e.
one of the coupled dots. The evolution of shell addition spectrum with magnetic
field provides Fock-Darwin spectra of s and p shell.Comment: 7 pages, 3 figures, Accepted for publication in Phys. Rev. Let
A review on data stream classification
At this present time, the significance of data streams cannot be denied as many researchers have placed their focus on the research areas of databases, statistics, and computer science. In fact, data streams refer to some data points sequences that are found in order with the potential to be non-binding, which is generated from the process of generating information in a manner that is not stationary. As such the typical tasks of searching data have been linked to streams of data that are inclusive of clustering, classification, and repeated mining of pattern. This paper presents several data stream clustering approaches, which are based on density, besides attempting to comprehend the function of the related algorithms; both semi-supervised and active learning, along with reviews of a number of recent studies
Few-electron molecular states and their transitions in a single InAs quantum dot molecule
We study electronic configurations in a single pair of vertically coupled
self-assembled InAs quantum dots, holding just a few electrons. By comparing
the experimental data of non-linear single-electron transport spectra in a
magnetic field with many-body calculations, we identify the spin and orbital
configurations to confirm the formation of molecular states by filling both the
quantum mechanically coupled symmetric and anti-symmetric states. Filling of
the anti-symmetric states is less favored with increasing magnetic field, and
this leads to various magnetic field induced transitions in the molecular
states.Comment: 14 pages, 3 figures, Accepted for publication in Phys. Rev. Let
Comparison of various methods for 3-D eddy current analysis
Computer codes developed for the A-φ, A-φ-Ω, A-Ω, T-Ω, and E-Ω methods are considered. Their accuracy, storage requirements, and CPU time are compared for linear eddy-current models. It is shown that the A-φ-Ω and T-Ω methods are preferable from the viewpoint of accuracy. The A-Ω and E-Ω methods are preferable with respect to storage and CPU time</p
Dasatinib inhibits CXCR4 signaling in chronic lymphocytic leukaemia cells and impairs migration towards CXCL12
Chemokines and their ligands play a critical role in enabling chronic lymphocytic leukaemia (CLL) cells access to protective microenvironmental niches within tissues, ultimately resulting in chemoresistance and relapse: disruption of these signaling pathways has become a novel therapeutic approach in CLL. The tyrosine kinase inhibitor dasatinib inhibits migration of several cell lines from solid-organ tumours, but effects on CLL cells have not been reported. We studied the effect of clinically achievable concentrations of dasatinib on signaling induced by the chemokine CXCL12 through its' receptor CXCR4, which is highly expressed on CLL cells. Dasatinib pre-treatment inhibited Akt and ERK phosphorylation in CLL cells upon stimulation with CXCL12. Dasatinib also significantly diminished the rapid increase in actin polymerisation observed in CLL cells following CXCL12 stimulation. Moreover, the drug significantly inhibited chemotaxis in a transwell assay, and reduced the percentage of cells able to migrate beneath a CXCL12-expressing murine stromal cell line. Dasatinib also abrogated the anti-apoptotic effect of prolonged CXCL12 stimulation on cultured CLL cells. These data suggest that dasatinib, akin to other small molecule kinase inhibitors targeting the B-cell receptor signaling pathway, may redistribute CLL cells from protective tissue niches to the peripheral blood, and support the investigation of dasatinib in combination strategies
Stress-driven instability in growing multilayer films
We investigate the stress-driven morphological instability of epitaxially
growing multilayer films, which are coherent and dislocation-free. We construct
a direct elastic analysis, from which we determine the elastic state of the
system recursively in terms of that of the old states of the buried layers. In
turn, we use the result for the elastic state to derive the morphological
evolution equation of surface profile to first order of perturbations, with the
solution explicitly expressed by the growth conditions and material parameters
of all the deposited layers. We apply these results to two kinds of multilayer
structures. One is the alternating tensile/compressive multilayer structure,
for which we determine the effective stability properties, including the effect
of varying surface mobility in different layers, its interplay with the global
misfit of the multilayer film, and the influence of asymmetric structure of
compressive and tensile layers on the system stability. The nature of the
asymmetry properties found in stability diagrams is in agreement with
experimental observations. The other multilayer structure that we study is one
composed of stacked strained/spacer layers. We also calculate the kinetic
critical thickness for the onset of morphological instability and obtain its
reduction and saturation as number of deposited layers increases, which is
consistent with recent experimental results. Compared to the single-layer film
growth, the behavior of kinetic critical thickness shows deviations for upper
strained layers.Comment: 27 pages, 11 figures; Phys. Rev. B, in pres
Robust automated detection of microstructural white matter degeneration in Alzheimer’s disease using machine learning classification of multicenter DTI data
Diffusion tensor imaging (DTI) based assessment of white matter fiber tract integrity can support the diagnosis of Alzheimer’s disease (AD). The use of DTI as a biomarker, however, depends on its applicability in a multicenter setting accounting for effects of different MRI scanners. We applied multivariate machine learning (ML) to a large multicenter sample from the recently created framework of the European DTI study on Dementia (EDSD). We hypothesized that ML approaches may amend effects of multicenter acquisition. We included a sample of 137 patients with clinically probable AD (MMSE 20.6±5.3) and 143 healthy elderly controls, scanned in nine different scanners. For diagnostic classification we used the DTI indices fractional anisotropy (FA) and mean diffusivity (MD) and, for comparison, gray matter and white matter density maps from anatomical MRI. Data were classified using a Support Vector Machine (SVM) and a Naïve Bayes (NB) classifier. We used two cross-validation approaches, (i) test and training samples randomly drawn from the entire data set (pooled cross-validation) and (ii) data from each scanner as test set, and the data from the remaining scanners as training set (scanner-specific cross-validation). In the pooled cross-validation, SVM achieved an accuracy of 80% for FA and 83% for MD. Accuracies for NB were significantly lower, ranging between 68% and 75%. Removing variance components arising from scanners using principal component analysis did not significantly change the classification results for both classifiers. For the scanner-specific cross-validation, the classification accuracy was reduced for both SVM and NB. After mean correction, classification accuracy reached a level comparable to the results obtained from the pooled cross-validation. Our findings support the notion that machine learning classification allows robust classification of DTI data sets arising from multiple scanners, even if a new data set comes from a scanner that was not part of the training sample
- …