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Hyang-Tag Lim, Emre Togan, Martin Kroner, Javier Miguel-Sanchez, Atac Imamoğlu
Neutral particles subject to artificial gauge potentials can behave as charged particles in magnetic fields. This fascinating premise has led to demonstrations of one-way waveguides, topologically protected edge states and Landau levels for photons. In ultracold neutral atoms, effective gauge fields have allowed the emulation of matter under strong magnetic fields leading to realization of Harper-Hofstadter and Haldane models. Here we show that application of perpendicular electric and magnetic fields effects a tunable artificial gauge potential for two-dimensional microcavity exciton polaritons...
February 23, 2017: Nature Communications
Cedric E Ginestet, Richard Emsley, Sabine Landau
A mental health trial is analyzed using a dose-response model, in which the number of sessions attended by the patients is deemed indicative of the dose of psychotherapeutic treatment. Here, the parameter of interest is the difference in causal treatment effects between the subpopulations that take part in different numbers of therapy sessions. For this data set, interactions between random treatment allocation and prognostic baseline variables provide the requisite instrumental variables. While the corresponding two-stage least squares (TSLS) estimator tends to have smaller bias than the ordinary least squares (OLS) estimator; the TSLS suffers from larger variance...
February 21, 2017: Statistics in Medicine
Marjolein Bruijning, Marco D Visser, Helene C Muller-Landau, S Joseph Wright, Liza S Comita, Stephen P Hubbell, Hans de Kroon, Eelke Jongejans
Dioecy has a demographic disadvantage compared with hermaphroditism: only about half of reproductive adults produce seeds. Dioecious species must therefore have fitness advantages to compensate for this cost through increased survival, growth, and/or reproduction. We used a full life cycle approach to quantify the demographic costs and benefits associated with dioecy while controlling for demographic differences between dioecious and hermaphroditic species related to other functional traits. The advantage of this novel approach is that we can focus on the effect of breeding system across a diverse tree community...
March 2017: American Naturalist
Ming Yang, Henry Chan, Gongpu Zhao, Joong Hwan Bahng, Peijun Zhang, Petr Král, Nicholas A Kotov
Nanoscale compartments are one of the foundational elements of living systems. Capsids, carboxysomes, exosomes, vacuoles and other nanoshells easily self-assemble from biomolecules such as lipids or proteins, but not from inorganic nanomaterials because of difficulties with the replication of spherical tiling. Here we show that stabilizer-free polydispersed inorganic nanoparticles (NPs) can spontaneously organize into porous nanoshells. The association of water-soluble CdS NPs into self-limited spherical capsules is the result of scale-modified electrostatic, dispersion and other colloidal forces...
March 2017: Nature Chemistry
Elliot Landau, Danielle Del Re, Bina Kviatkovsky, Aryeh Rothstein, Jonathan Scheiner, Cheryl Lin
OBJECTIVES: Since 2009, the rate of nondiagnostic (ND) thyroid nodule fine-needle aspiration (FNA) has ranged from 2% to 20%. A ND result can cause further patient morbidity secondary to repeated procedures and delay in diagnosis. The use of real-time strain elastography (RTE) in determining nodule malignant risk has gained considerable focus recently. A less studied area where RTE may prove beneficial is its role in targeting areas for FNA. Our hypothesis is that FNA performed in concurrence with RTE will show a decreased rate of ND results leading to fewer repeated FNA...
2017: Journal of Clinical Imaging Science
Biswajit Datta, Santanu Dey, Abhisek Samanta, Hitesh Agarwal, Abhinandan Borah, Kenji Watanabe, Takashi Taniguchi, Rajdeep Sensarma, Mandar M Deshmukh
Quantum Hall effect provides a simple way to study the competition between single particle physics and electronic interaction. However, electronic interaction becomes important only in very clean graphene samples and so far the trilayer graphene experiments are understood within non-interacting electron picture. Here, we report evidence of strong electronic interactions and quantum Hall ferromagnetism seen in Bernal-stacked trilayer graphene. Due to high mobility ∼500,000 cm(2 )V(-1 )s(-1) in our device compared to previous studies, we find all symmetry broken states and that Landau-level gaps are enhanced by interactions; an aspect explained by our self-consistent Hartree-Fock calculations...
February 20, 2017: Nature Communications
Samuel F Bakhoum, Dan Avi Landau
Large-scale, massively parallel sequencing of human cancer samples has revealed tremendous genetic heterogeneity within individual tumors. Indeed, tumors are composed of an admixture of diverse subpopulations-subclones-that vary in space and time. Here, we discuss a principal driver of clonal diversification in cancer known as chromosomal instability (CIN), which complements other modes of genetic diversification creating the multilayered genomic instability often seen in human cancer. Cancer cells have evolved to fine-tune chromosome missegregation rates to balance the acquisition of heterogeneity while preserving favorable genotypes, a dependence that can be exploited for a therapeutic benefit...
February 17, 2017: Cold Spring Harbor Perspectives in Medicine
Alexander Georgi, Peter Nemes-Incze, Ramon Carrillo-Bastos, Daiara Faria, Silvia Viola Kusminskiy, Dawei Zhai, Martin Schneider, Dinesh Subramaniam, Torge Mashoff, Nils Michael Freitag, Marcus Liebmann, Marco Pratzer, Ludger Wirtz, Colin R Woods, Roman Vladislavovich Gorbachev, Yang Cao, Kostya S Novoselov, Nancy Sandler, Markus Morgenstern
One of the intriguing characteristics of honeycomb lattices is the appearance of a pseudo-magnetic field as a result of mechanical deformation. In the case of graphene, the Landau quantization resulting from this pseudo-magnetic field has been measured using scanning tunneling microscopy. Here we show that a signature of the pseudo-magnetic field is a local sublattice symmetry breaking observable as a redistribution of the local density of states. This can be interpreted as a polarization of graphene's pseudospin due to a strain induced pseudo-magnetic field, in analogy to the alignment of a real spin in a magnetic field...
February 17, 2017: Nano Letters
Johannes Binder, Freddie Withers, Maciej R Molas, Clement Faugeras, Karol Nogajewski, Kenji Watanabe, Takashi Taniguchi, Aleksey Kozikov, Andre K Geim, Kostya S Novoselov, Marek Potemski
We report on experimental investigations of an electrically driven WSe2 based light-emitting van der Waals heterostructure. We observe a threshold voltage for electroluminescence significantly lower than the corresponding single particle band gap of monolayer WSe2. This observation can be interpreted by considering the Coulomb interaction and a tunneling process involving excitons, well beyond the picture of independent charge carriers. An applied magnetic field reveals pronounced magneto-oscillations in the electroluminescence of the free exciton emission intensity with a 1/B-periodicity...
February 17, 2017: Nano Letters
Katsuya Miura, Shin Yabuuchi, Masaki Yamada, Masahiko Ichimura, Bivas Rana, Susumu Ogawa, Hiromasa Takahashi, Yasuhiro Fukuma, Yoshichika Otani
Recent progress in magnetic tunnel junctions (MTJs) with a perpendicular easy axis consisting of CoFeB and MgO stacking structures has shown that magnetization dynamics are induced due to voltage-controlled magnetic anisotropy (VCMA), which will potentially lead to future low-power-consumption information technology. For manipulating magnetizations in MTJs by applying voltage, it is necessary to understand the coupled magnetization motion of two magnetic (recording and reference) layers. In this report, we focus on the magnetization motion of two magnetic layers in MTJs consisting of top layers with an in-plane easy axis and bottom layers with a perpendicular easy axis, both having perpendicular magnetic anisotropy...
February 17, 2017: Scientific Reports
Nuno M Silvestre, M Tasinkevych
The Landau-de Gennes free energy is used to study theoretically the effective interaction of spherical "key" and anisotropic "lock" colloidal particles. We assume identical anchoring properties of the surfaces of the key and of the lock particles, and we consider planar degenerate and perpendicular anchoring conditions separately. The lock particle is modeled as a spherical particle with a spherical dimple. When such a particle is introduced into a nematic liquid crystal, it orients its dimple at an oblique angle θ_{eq} with respect to the far field director n_{∞}...
January 2017: Physical Review. E
Grant M Rotskoff, Gavin E Crooks, Eric Vanden-Eijnden
Optimal control of nanomagnets has become an urgent problem for the field of spintronics as technological tools approach thermodynamically determined limits of efficiency. In complex, fluctuating systems, such as nanomagnetic bits, finding optimal protocols is challenging, requiring detailed information about the dynamical fluctuations of the controlled system. We provide a physically transparent derivation of a metric tensor for which the length of a protocol is proportional to its dissipation. This perspective simplifies nonequilibrium optimization problems by recasting them in a geometric language...
January 2017: Physical Review. E
Makoto Yamaguchi, Tatsuro Yuge, Tetsuo Ogawa
By introducing a temporal change time scale τ_{A}(t) for the time-dependent system Hamiltonian, a general formulation of the Markovian quantum master equation is given to go well beyond the adiabatic regime. In appropriate situations, the framework is well justified even if τ_{A}(t) is faster than the decay time scale of the bath correlation function. An application to the dissipative Landau-Zener model demonstrates this general result. The findings are applicable to a wide range of fields, providing a basis for quantum control beyond the adiabatic regime...
January 2017: Physical Review. E
Ana R Fialho, Nelson R Bernardino, Nuno M Silvestre, Margarida M Telo da Gama
The confinement of liquid crystals inside curved geometries leads to exotic structures, with applications ranging from biosensors to optical switches and privacy windows. Here we study how curvature affects the alignment of a cholesteric liquid crystal. We model the system on the mesoscale using the Landau-de Gennes model. Our study was performed in three stages, analyzing different curved geometries from cylindrical walls and pores, to toroidal domains, in order to isolate the curvature effects. Our results show that the stresses introduced by the curvature influence the orientation of the liquid crystal molecules, and cause distortions in the natural periodicity of the cholesteric that depend on the radius of curvature, on the pitch, and on the dimensions of the system...
January 2017: Physical Review. E
Rohit Singh, Kishore Dutta, Malay K Nandy
A recent theoretical study [Phys. Rev. Lett. 112, 037202 (2014)10.1103/PhysRevLett.112.037202] has revealed that systems such as uranium ferromagnetic superconductors obey conserved dynamics. To capture the critical behavior near the paramagnetic to ferromagnetic phase transition of these compounds, we study the conserved critical dynamics of a nonlocal Ginzburg-Landau model. A dynamic renormalization-group calculation at one-loop order yields the critical indices in the leading order of ε=d_{c}-d, where d_{c}=4-2ρ is the upper critical dimension, with ρ an exponent in the nonlocal interaction...
January 2017: Physical Review. E
Zhongkui Sun, Ning Ma, Wei Xu
In this paper, the effects of random errors on the oscillating behaviors have been studied theoretically and numerically in a prototypical coupled nonlinear oscillator. Two kinds of noises have been employed respectively to represent the measurement errors accompanied with the parameter specifying the distance from a Hopf bifurcation in the Stuart-Landau model. It has been demonstrated that when the random errors are uniform random noise, the change of the noise intensity can effectively increase the robustness of the system...
February 15, 2017: Scientific Reports
B E Grüter, A Pangalu, K Landau, W Wichmann
No abstract text is available yet for this article.
February 9, 2017: Clinical Neuroradiology
Haibo Yao, Mingfeng Zhu, Liwei Jiang, Yisong Zheng
We perform a numerical simulation on time evolution of electronic wave packet in a Weyl semimetal(WSM) slab driven by a magnetic field. We find that the evolution trajectory of the wave packet depends sensitively on its initial spin state. Only the initial spin state being identical to that of the Fermi arc state at the surface it localized, does the wave packet evolution demonstrate the characteristic cyclotron orbit of WSM predicted previously from a semiclassical viewpoint. By analyzing the eigen-expansion of the electronic wave packet, we find the chiral Landau Levels(LLs) of the WSM slab, as an ingredient of the wave packet, is responsible for establishing the characteristic cyclotron orbit of Weyl semimetal...
February 9, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Asnat Walfisch, Tamar Wainstock, Ofer Beharier, Daniella Landau, Eyal Sheiner
BACKGROUND: Preterm delivery may affect the development of the upper airways resulting in a higher risk of obstructive sleep apnoea (OSA). We investigated whether children born at early term (37-38 6/7 weeks' gestation) are at an increased risk for childhood OSA as compared with those born later. METHODS: In this population-based cohort analysis all singleton deliveries occurring between 1991-2013 at a single regional tertiary medical centre were included. Gestational age upon delivery was sub-divided into: early preterm (<33 6/7 weeks' gestation), late preterm (34-36 6/7), early term, full term (39-40 6/7), late term (41-41 6/7), and post term (>42 0/7)...
March 2017: Paediatric and Perinatal Epidemiology
Marie-Louise Meng, Ruth Landau, Olof Viktorsdottir, Jennifer Banayan, Tamila Grant, Brian Bateman, Richard Smiley, Elena Reitman
OBJECTIVE: To identify whether pregnancy outcomes vary by etiology and severity of pulmonary hypertension and whether contemporary therapies influence outcomes. METHODS: A retrospective review of medical records at four academic institutions was conducted to identify pregnant women with pulmonary hypertension (2001-2015). International Classification of Diseases, 9th Revision codes for pulmonary hypertension and pregnancy were used to identify potential participants...
March 2017: Obstetrics and Gynecology
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