1,158 research outputs found
Replica-molded electro-optic polymer Mach–Zehnder modulator
A Mach-Zehnder electro-optic polymer amplitude modulator is fabricated by a simple and high-throughput soft-stamp replica-molding technique. The modulator structure incorporates the highly nonlinear and stable chromophore, AJL8, doped in amorphous polycarbonate. Single-arm phase-retardation results in a halfwave voltage (V-pi) of 8.4 V at 1600 nm. The on/off extinction ratio is better than 19 dB, resulting from precise Y-branch power splitters and good waveguide uniformity. These results indicate that the simple fabrication process allows for good optical performance from high-fidelity replicas of the original master devices
Spatial Confinement Affects the Heterogeneity and Interactions Between Shoaling Fish
Living objects are able to consume chemical energy and process information
independently from others. However, living objects can coordinate to form
ordered groups such as schools of fish. This work considers these complex
groups as living materials and presents imaging-based experiments of laboratory
schools of fish to understand how this non-equilibrium activity affects the
mechanical properties of a group. We use spatial confinement to control the
motion and structure of fish within quasi-2D shoals of fish. Using image
analysis techniques, we make quantitative observations of the structures, their
spatial heterogeneity, and their temporal fluctuations. Furthermore, we utilize
Monte Carlo simulations to replicate the experimentally observed area
distribution patterns which provide insight into the effective interactions
between fish and confirm the presence of a confinement-based behavioral
preference transition. In addition, unlike in short-range interacting systems,
here structural heterogeneity and dynamic activities are positively correlated
as a result of complex interplay between spatial arrangement and behavioral
dynamics in fish collectives.Comment: 18 pages, 7 Figure
Active Sampling Based on MMD for Model Adaptation
© 2019, ICST Institute for Computer Sciences, Social Informatics and Telecommunications Engineering. In this paper, we demonstrate a method for transfer learning with minimal supervised information. Recently, researchers have proposed various algorithms to solve transfer learning problems, especially the unsupervised domain adaptation problem. They mainly focus on how to learn a good common representation and use it directly for downstream task. Unfortunately, they ignore the fact that this representation may not capture target-specific feature for target task well. In order to solve this problem, this paper attempts to capture target-specific feature by utilizing labeled data in target domain. Now it’s a challenge that how to seek as little supervised information as possible to achieve good results. To overcome this challenge, we actively select instances for training and model adaptation based on MMD method. In this process, we try to label some valuable target data to capture target-specific feature and fine-tune the classifier networks. We choose a batch of data in target domain far from common representation space and having maximum entropy. The first requirement is helpful to learn a good representation for target domain and the second requirement tries to improve the classifier performance. Finally, we experiment with our method on several datasets which shows significant improvement and competitive advantage against common methods
All-organic and organic-silicon photonic ring micro-resonators
Organic electro-optic materials offer exceptional processability (both from solution and the gas phase) that permit fabrication of flexible and conformal device structures and the integration of organic materials with a wide range of disparate materials. In addition, organic electro-optical materials have fundamental response times that are in the terahertz region, and useable electro-optic coefficients that are approaching 300 pm/V (at telecommunication wavelengths). In addition to fabrication by traditional lithographic methods, multiple devices on a single wafer have been fabricated by soft and nano-imprint lithography. In this presentation, we review the fabrication and performance evaluation of a number of all-organic and organic-silicon photonic ring microresonator devices. Both electrical and thermal tuning of devices, including both single and multiple ring micro-resonators, are demonstrated
Generation of continuous variable squeezing and entanglement of trapped ions in time-varying potentials
We investigate the generation of squeezing and entanglement for the motional
degrees of freedom of ions in linear traps, confined by time-varying and
oscillating potentials, comprised of an DC and an AC component. We show that
high degrees of squeezing and entanglement can be obtained by controlling
either the DC or the AC trapping component (or both), and by exploiting
transient dynamics in regions where the ions' motion is unstable, without any
added optical control. Furthermore, we investigate the time-scales over which
the potentials should be switched in order for the manipulations to be most
effective.Comment: 10 pages, submitted to Quantum Information Processing (special issue
on Quantum Decoherence and Entanglement
Imaging Electronic Correlations in Twisted Bilayer Graphene near the Magic Angle
Twisted bilayer graphene with a twist angle of around 1.1{\deg} features a
pair of isolated flat electronic bands and forms a strongly correlated
electronic platform. Here, we use scanning tunneling microscopy to probe local
properties of highly tunable twisted bilayer graphene devices and show that the
flat bands strongly deform when aligned with the Fermi level. At half filling
of the bands, we observe the development of gaps originating from correlated
insulating states. Near charge neutrality, we find a previously unidentified
correlated regime featuring a substantially enhanced flat band splitting that
we describe within a microscopic model predicting a strong tendency towards
nematic ordering. Our results provide insights into symmetry breaking
correlation effects and highlight the importance of electronic interactions for
all filling factors in twisted bilayer graphene.Comment: Main text 9 pages, 4 figures; Supplementary Information 25 page
Genome wide association mapping of grain arsenic, copper, molybdenum and zinc in rice (Oryza sativa L.) grown at four international field sites
Peer reviewedPublisher PD
Polycation-π Interactions Are a Driving Force for Molecular Recognition by an Intrinsically Disordered Oncoprotein Family
Molecular recognition by intrinsically disordered proteins (IDPs) commonly involves specific localized contacts and target-induced disorder to order transitions. However, some IDPs remain disordered in the bound state, a phenomenon coined "fuzziness", often characterized by IDP polyvalency, sequence-insensitivity and a dynamic ensemble of disordered bound-state conformations. Besides the above general features, specific biophysical models for fuzzy interactions are mostly lacking. The transcriptional activation domain of the Ewing's Sarcoma oncoprotein family (EAD) is an IDP that exhibits many features of fuzziness, with multiple EAD aromatic side chains driving molecular recognition. Considering the prevalent role of cation-π interactions at various protein-protein interfaces, we hypothesized that EAD-target binding involves polycation- π contacts between a disordered EAD and basic residues on the target. Herein we evaluated the polycation-π hypothesis via functional and theoretical interrogation of EAD variants. The experimental effects of a range of EAD sequence variations, including aromatic number, aromatic density and charge perturbations, all support the cation-π model. Moreover, the activity trends observed are well captured by a coarse-grained EAD chain model and a corresponding analytical model based on interaction between EAD aromatics and surface cations of a generic globular target. EAD-target binding, in the context of pathological Ewing's Sarcoma oncoproteins, is thus seen to be driven by a balance between EAD conformational entropy and favorable EAD-target cation-π contacts. Such a highly versatile mode of molecular recognition offers a general conceptual framework for promiscuous target recognition by polyvalent IDPs. © 2013 Song et al
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