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Datun Qi, Yuan Gao, Gan-Xin Yan
No abstract text is available yet for this article.
August 10, 2018: Heart Rhythm: the Official Journal of the Heart Rhythm Society
Kristina Preuer, Philipp Renz, Thomas Unterthiner, Sepp Hochreiter, G Uuml Nter Klambauer
The new wave of successful generative models in machine learning has increased the interest in deep learning driven de novo drug design. However, method comparison is difficult because of various flaws of the currently employed evaluation metrics. We propose an evaluation metric for generative models called Fréchet ChemblNet distance (FCD). The FCD's advantage over previous metrics is that it can detect whether generated molecules are diverse and have similar chemical and biological properties as real molecules...
August 17, 2018: Journal of Chemical Information and Modeling
Madelyne Z Greene, Tonda L Hughes, Marilyn S Sommers, Alexandra Hanlon, Salimah H Meghani
BACKGROUND: Sexual minority women (SMW) face barriers to healthcare that may result in lower utilization of cervical cancer screening. Previous experiences with the healthcare system-specifically reproductive health-related encounters-have the potential to affect future use of screening services. This study aimed to examine the association between pregnancy history and cervical cancer screening in a diverse sample of SMW. Anderson's Behavioral Model of Health Services Use guided the selection of variables included in the study...
August 17, 2018: Journal of Women's Health
J F Haase, Z-Y Wang, J Casanova, M B Plenio
We propose a quantum control scheme aimed at interacting systems that gives rise to highly selective coupling among their near-to-resonance constituents. Our protocol implements temporal control of the interaction strength, switching it on and off again adiabatically. This soft temporal modulation significantly suppresses off-resonant contributions in the interactions. Among the applications of our method we show that it allows us to perform an efficient rotating-wave approximation in a wide parameter regime, the elimination of side peaks in quantum sensing experiments, and selective high-fidelity entanglement gates on nuclear spins with close frequencies...
August 3, 2018: Physical Review Letters
David Colas, Fabrice P Laussy, Matthew J Davis
Negative effective masses can be realized by engineering the dispersion relation of a variety of quantum systems. A recent experiment with spin-orbit coupled Bose-Einstein condensates has shown that a negative effective mass can halt the free expansion of the condensate and lead to fringes in the density [M. A. Khamehchi et al., Phys. Rev. Lett. 118, 155301 (2017)PRLTAO0031-900710.1103/PhysRevLett.118.155301]. Here, we show that the underlying cause of these observations is the self-interference of the wave packet that arises when only one of the two effective mass parameters that characterize the dispersion of the system is negative...
August 3, 2018: Physical Review Letters
Renwen Yu, Qiushi Guo, Fengnian Xia, F Javier García de Abajo
Nanoscale photothermal sources find important applications in theranostics, imaging, and catalysis. In this context, graphene offers a unique suite of optical, electrical, and thermal properties, which we exploit to show self-consistent active photothermal modulation of its nanoscale response. In particular, we predict the existence of plasmons confined to the optical landscape tailored by continuous-wave external-light pumping of homogeneous graphene. This result relies on the high electron temperatures achievable in optically pumped clean graphene while its lattice remains near ambient temperature...
August 3, 2018: Physical Review Letters
Song Ming Du, Yanbei Chen
Quantum gravity corrections have been speculated to lead to modifications to space-time geometry near black-hole horizons. Such structures may reflect gravitational waves, causing echoes that follow the main gravitational waves from binary black-hole coalescence. By studying two phenomenological models of the near-horizon structures under the Schwarzschild approximation, we show that such echoes, if they exist, will give rise to a stochastic gravitational-wave background, which is very substantial if the near-horizon structure has a near-unity reflectivity for gravitational waves, readily detectable by Advanced LIGO...
August 3, 2018: Physical Review Letters
Vilmos Kocsis, Karlo Penc, Toomas Rõõm, Urmas Nagel, Jakub Vít, Judit Romhányi, Yusuke Tokunaga, Yasujiro Taguchi, Yoshinori Tokura, István Kézsmárki, Sándor Bordács
The ultimate goal of multiferroic research is the development of a new-generation nonvolatile memory devices, where magnetic bits are controlled via electric fields with low energy consumption. Here, we demonstrate the optical identification of magnetoelectric (ME) antiferromagnetic (AFM) domains in the LiCoPO_{4} exploiting the strong absorption difference between the domains. This unusual contrast, also present in zero magnetic field, is attributed to the dynamic ME effect of the spin-wave excitations, as confirmed by our microscopic model, which also captures the characteristics of the observed static ME effect...
August 3, 2018: Physical Review Letters
Jooseop Lee, Masaaki Matsuda, John A Mydosh, Igor Zaliznyak, Alexander I Kolesnikov, Stefan Süllow, Jacob P C Ruff, Garrett E Granroth
The duality between the localized and itinerant nature of magnetism in 5f-electron systems has been a long-standing puzzle. Here, we report inelastic neutron scattering measurements, which reveal both local and itinerant aspects of magnetism in a single-crystalline system of UPt_{2}Si_{2}. In the antiferromagnetic state, we observe a broad continuum of diffuse magnetic scattering with a resonancelike gap of ≈7  meV and the surprising absence of coherent spin waves, suggestive of itinerant magnetism. While the gap closes above the Néel temperature, strong dynamic spin correlations persist to a high temperature...
August 3, 2018: Physical Review Letters
Wenqin Shi, Vincent Callewaert, Bernardo Barbiellini, Rolando Saniz, Maik Butterling, Werner Egger, Marcel Dickmann, Christoph Hugenschmidt, Behtash Shakeri, Robert W Meulenberg, Ekkes Brück, Bart Partoens, Arun Bansil, Stephan W H Eijt
Previous studies have shown that positron-annihilation spectroscopy is a highly sensitive probe of the electronic structure and surface composition of ligand-capped semiconductor quantum dots (QDs) embedded in thin films. The nature of the associated positron state, however, whether the positron is confined inside the QDs or localized at their surfaces, has so far remained unresolved. Our positron-annihilation lifetime spectroscopy studies of CdSe QDs reveal the presence of a strong lifetime component in the narrow range of 358-371 ps, indicating abundant trapping and annihilation of positrons at the surfaces of the QDs...
August 3, 2018: Physical Review Letters
Misao Sasaki, Teruaki Suyama, Takahiro Tanaka, Shuichiro Yokoyama
This corrects the article DOI: 10.1103/PhysRevLett.117.061101.
August 3, 2018: Physical Review Letters
Morten H Christensen, Peter P Orth, Brian M Andersen, Rafael M Fernandes
Recent experiments in iron pnictide superconductors reveal that, as the putative magnetic quantum critical point is approached, different types of magnetic order coexist over a narrow region of the phase diagram. Although these magnetic configurations share the same wave vectors, they break distinct symmetries of the lattice. Importantly, the highest superconducting transition temperature takes place close to this proliferation of near-degenerate magnetic states. In this Letter, we employ a renormalization group calculation to show that such a behavior naturally arises due to the effects of spin-orbit coupling on the quantum magnetic fluctuations...
August 3, 2018: Physical Review Letters
S G Baek, G M Wallace, P T Bonoli, D Brunner, I C Faust, A E Hubbard, J W Hughes, B LaBombard, R R Parker, M Porkolab, S Shiraiwa, S Wukitch
Efficient lower hybrid current drive (LHCD) is demonstrated at densities up to n[over ¯]_{e}≈1.5×10^{20}  m^{-3} in diverted plasmas on the Alcator C-Mod tokamak by operating at increased plasma current-and therefore reduced Greenwald density fraction. This density exceeds the nominal "LH density limit" at n[over ¯]_{e}≈1.0×10^{20}  m^{-3} reported previously, above which an anomalous loss of current drive efficiency was observed. The recovery of current drive efficiency to a level consistent with engineering scalings is correlated with a reduction in density shoulders and turbulence levels in the far scrape-off layer...
August 3, 2018: Physical Review Letters
Balázs Dóra, Balázs Hetényi, Cătălin Paşcu Moca
Motivated by recent experiments in ultracold gases, we focus on the properties of the center-of-mass coordinate of an interacting one-dimensional Fermi gas, displaying several distinct phases. While the variance of the center of mass vanishes in insulating phases such as phase-separated and charge density wave phases, it remains finite in the metallic phase, which realizes a Luttinger liquid. By combining numerics with bosonization, we demonstrate that the autocorrelation function of the center-of-mass coordinate is universal throughout the metallic phase...
August 3, 2018: Physical Review Letters
Zheng Kun Yang, Cheng-Zong Yuan, An-Wu Xu
The development of low-cost and highly efficient single-atom oxygen reduction catalysts to replace platinum for fuel cells and metal-air cells is highly desirable but remains challenging. Herein, we report the fabrication of isolated single-atom Fe anchored on porous nitrogen-doped carbon from the pyrolysis of a well-designed solely Fe-tetrapyridophenazine coordination complex. The N-rich bridging ligand, tetrapyridophenazine (tpphz) is first employed as a spatial isolation agent of Fe that suppresses its aggregation during high temperature pyrolysis, resulting in highly reactive and stable single-atom Fe ORR catalysts...
August 17, 2018: Nanoscale
Cheng-Wu You, Chengchangfeng Lu, Tian-Yi Wang, Shun-Rong Qian, Zhen-Gang Yang, Ke-Jia Wang, Jin-Song Liu, Sheng-Lie Wang
In this paper, a neoteric algorithm based on a two-dimensional continuous wavelet transform is developed to get the defect contour in the terahertz (THz) non-destructive testing result obtained from a raster-scan frequency-modulated continuous-wave (FMCW) THz imaging system. In order to prove the method's validity, an experiment is carried out. The result of the experiment shows that the method allows one to extract the defect contour from the THz FMCW interference with severe stripe noises. Moreover, the relative error of defect area between the actual value and that obtained from the extracted defect contour is no more than 3...
June 10, 2018: Applied Optics
Zao Xu, Dick K P Yue
In measuring the coefficient of variation (CV) of underwater wave-induced sunlight irradiance, the spatial integration of irradiance signals due to the finite aperture size of an irradiance detector usually causes underestimation of the measured variance. Because this spatial integration effect is strongly coupled with ocean wave features, inherent optical properties (IOPs) of water, and atmospheric radiance conditions, direct deconvolution techniques from measured irradiance signals can lead to serious signal-to-noise degradation in a noisy upper ocean...
June 10, 2018: Applied Optics
Qun Hao, Shaopu Wang, Yao Hu, Yifeng Tan, Tengfei Li, Shanshan Wang
Measurement of aspheric and freeform surfaces remains challenging due to the various shapes of the surface under test (SUT), especially when the SUT has a large aperture and strong deviation from the spherical surface. This paper proposes a two-step carrier-wave stitching method to enlarge the measurement bandwidth of a digital Moiré interferometry. Then, measurements of aspheric and freeform surfaces with a standard spherical interferometer without a phase-shifting mechanism are demonstrated. Experimental results with a root-mean-square repeatability of better than 1/200λ present good consistency to UA3P contact measurement results...
June 10, 2018: Applied Optics
Benjamin D Kaebe, Nickolas P Robins, Toby K Boyson, Harald Kleine, Sean O'Byrne
This paper presents 1.6 MHz scan rate, non-intrusive, time-resolved temperature measurements of a normal shock reflection from a plane end wall within a shock tube. A vertical-cavity surface-emitting laser (VCSEL) was used to conduct tunable diode laser absorption spectroscopy with water vapor as the probe species. The results are compared with analytical predictions. Temperatures measured with this technique agree within a single-scan standard deviation of ±33  K with calculated temperatures at a VCSEL modulation frequency of 800 kHz, which is sufficiently rapid enough to be used to investigate highly transient shock wave interaction processes...
July 10, 2018: Applied Optics
Kazusa Oe, Takanori Nomura
Phase imaging by digital holography is widely used. An in-line optical setup is preferable for a practical use. A twin image, however, is a serious obstacle to achievement of high-quality phase imaging in in-line digital holography. For in-line digital holography, a time-division phase-shifting method or a wave-splitting phase-shifting method is used to eliminate the twin image. The former requires multiple exposures, and the latter requires specially designed optical elements. To solve these problems, a twin-image reduction method using a diffuser is proposed...
July 10, 2018: Applied Optics
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