Nd-doped aluminum oxide integrated amplifiers at 880 nm, 1060 nm, and 1330 nm

Neodymium-doped Al2O3 layers were deposited on thermally oxidized Si substrates and channel waveguides were patterned using reactive-ion etching. Internal net gain on the Nd3+ transitions at 880, 1064, and 1330 nm was investigated,\ud yielding a maximum gain of 6.3 dB/cm at 1064 nm. Values for the energy-transfer upconversion parameter for different Nd3+\ud concentrations were deduced

AdaSampling for positive-unlabeled and label noise learning with bioinformatics applications

© 2018 IEEE. Class labels are required for supervised learning but may be corrupted or missing in various applications. In binary classification, for example, when only a subset of positive instances is labeled whereas the remaining are unlabeled, positive-unlabeled (PU) learning is required to model from both positive and unlabeled data. Similarly, when class labels are corrupted by mislabeled instances, methods are needed for learning in the presence of class label noise (LN). Here we propose adaptive sampling (AdaSampling), a framework for both PU learning and learning with class LN. By iteratively estimating the class mislabeling probability with an adaptive sampling procedure, the proposed method progressively reduces the risk of selecting mislabeled instances for model training and subsequently constructs highly generalizable models even when a large proportion of mislabeled instances is present in the data. We demonstrate the utilities of proposed methods using simulation and benchmark data, and compare them to alternative approaches that are commonly used for PU learning and/or learning with LN. We then introduce two novel bioinformatics applications where AdaSampling is used to: 1) identify kinase-substrates from mass spectrometry-based phosphoproteomics data and 2) predict transcription factor target genes by integrating various next-generation sequencing data

Vibration based damage identification of a scale-model steel frame structure subjected to bolt connection failures

Large-span steel frame structures prove to be an ideal choice for their speed of construction, relatively low cost, strength, durability and structural design flexibility. For this type of structure, the beam-column connections are critical for its structural integrity and overall stability. This is because a steel frame generally fails first at its connectors, due to the change in stress redistribution with adjacent members and material related failures, caused by various factors such as fire, seismic activity or material deterioration. Since particular attention is required at a steel frame’s connection points, this study explores the applicability of a comprehensive structural health monitoring (SHM) method to identify early damage and prolong the lifespan of connection points of steel frames. An impact hammer test was performed on a scale-model steel frame structure, recording its dynamic response to the hammer strike via an accelerometer. The testing procedure included an intact scenario and two damage scenarios by unfastening four bolt connections in an accumulating order. Based entirely on time-domain experimental data for its calibration, an Auto Regressive Average Exogenous (ARMAX) model is used to create a simple and accurate model for vibration simulation. The calibrated ARMAX model is then used to identify various bolt-connection related damage scenarios via R2 value. The findings in this study suggest that the proposed time-domain approach is capable of identifying structural damage in a parsimonious manner and can be used as a quick or initial solution

On-chip integrated amplifiers and lasers utilizing rare-earth-ion activation

This contribution reviews our recent results on rare-earth-ion-doped integrated amplifiers and lasers. We have concentrated our efforts on complex-doped polymers, amorphous Al2O3, and crystalline potassium double tungstates

Inverse-designed diamond photonics

Diamond hosts optically active color centers with great promise in quantum computation, networking, and sensing. Realization of such applications is contingent upon the integration of color centers into photonic circuits. However, current diamond quantum optics experiments are restricted to single devices and few quantum emitters because fabrication constraints limit device functionalities, thus precluding color center integrated photonic circuits. In this work, we utilize inverse design methods to overcome constraints of cutting-edge diamond nanofabrication methods and fabricate compact and robust diamond devices with unique specifications. Our design method leverages advanced optimization techniques to search the full parameter space for fabricable device designs. We experimentally demonstrate inverse-designed photonic free-space interfaces as well as their scalable integration with two vastly different devices: classical photonic crystal cavities and inverse-designed waveguide-splitters. The multi-device integration capability and performance of our inverse-designed diamond platform represents a critical advancement toward integrated diamond quantum optical circuits

Integrated optical backplane amplifier

A solution for compensating losses in optical interconnects is provided. Large-core Al2O3:Nd3+ channel waveguide amplifiers are characterized and tested in combination with passive polymer waveguides. Coupling losses between the two waveguides are investigated in order to optimize the channel geometries of the two waveguide types. A tapered Al2O3:Nd3+ waveguide is designed to improve the pump intensity in the active region. A maximum 0.21-dB net gain at a signal wavelength of 880 nm is demonstrated in a structure in which an Al2O3:Nd3+ waveguide is coupled between two polymer waveguides. The gain can be improved by increasing the pump power and adjusting the waveguide properties of the amplifier

Neuroimaging Evidence of Major Morpho-Anatomical and Functional Abnormalities in the BTBR T+TF/J Mouse Model of Autism

BTBR T+tf/J (BTBR) mice display prominent behavioural deficits analogous to the defining symptoms of autism, a feature that has prompted a widespread use of the model in preclinical autism research. Because neuro-behavioural traits are described with respect to reference populations, multiple investigators have examined and described the behaviour of BTBR mice against that exhibited by C57BL/6J (B6), a mouse line characterised by high sociability and low self-grooming. In an attempt to probe the translational relevance of this comparison for autism research, we used Magnetic Resonance Imaging (MRI) to map in both strain multiple morpho-anatomical and functional neuroimaging readouts that have been extensively used in patient populations. Diffusion tensor tractography confirmed previous reports of callosal agenesis and lack of hippocampal commissure in BTBR mice, and revealed a concomitant rostro-caudal reorganisation of major cortical white matter bundles. Intact inter-hemispheric tracts were found in the anterior commissure, ventro-medial thalamus, and in a strain-specific white matter formation located above the third ventricle. BTBR also exhibited decreased fronto-cortical, occipital and thalamic gray matter volume and widespread reductions in cortical thickness with respect to control B6 mice. Foci of increased gray matter volume and thickness were observed in the medial prefrontal and insular cortex. Mapping of resting-state brain activity using cerebral blood volume weighted fMRI revealed reduced cortico-thalamic function together with foci of increased activity in the hypothalamus and dorsal hippocampus of BTBR mice. Collectively, our results show pronounced functional and structural abnormalities in the brain of BTBR mice with respect to control B6 mice. The large and widespread white and gray matter abnormalities observed do not appear to be representative of the neuroanatomical alterations typically observed in autistic patients. The presence of reduced fronto-cortical metabolism is of potential translational relevance, as this feature recapitulates previously-reported clinical observations

Membrane-Associated Transporter Protein (MATP) Regulates Melanosomal pH and Influences Tyrosinase Activity

The SLC45A2 gene encodes a Membrane-Associated Transporter Protein (MATP). Mutations of this gene cause oculocutaneous albinism type 4 (OCA4). However, the molecular mechanism of its action in melanogenesis has not been elucidated. Here, we discuss the role of MATP in melanin production. The SLC45A2 gene is highly enriched in human melanocytes and melanoma cell lines, and its protein, MATP, is located in melanosomes. The knockdown of MATP using siRNAs reduced melanin content and tyrosinase activity without any morphological change in melanosomes or the expression of melanogenesis-related proteins. Interestingly, the knockdown of MATP significantly lowered the melanosomal pH, as verified through DAMP analysis, suggesting that MATP regulates melanosomal pH and therefore affects tyrosinase activity. Finally, we found that the reduction of tyrosinase activity associated with the knockdown of MATP was readily recovered by copper treatment in the in vitro L-DOPA oxidase activity assay of tyrosinase. Considering that copper is an important element for tyrosinase activity and that its binding to tyrosinase depends on melanosomal pH, MATP may play an important role in regulating tyrosinase activity via controlling melanosomal pH.112820Ysciescopu