Separate Output Research Articles

On-chip interference of single photons from an embedded quantum dot and an external laser

In this work, we demonstrate the on-chip two-photon interference between single photons emitted by a single self-assembled InGaAs quantum dot and an external laser. The quantum dot is embedded within one arm of an air-clad directional coupler which acts as a beam-splitter for incoming light. Photons originating from an attenuated external laser are coupled to the second arm of the beam-splitter and then combined with the quantum dot photons, giving rise to two-photon quantum interference between dissimilar sources. We verify the occurrence of on-chip Hong-Ou-Mandel interference by cross-correlating the optical signal from the separate output ports of the directional coupler. This experimental approach allows us to use a classical light source (laser) to assess in a single step the overall device performance in the quantum regime and probe quantum dot photon indistinguishability on application realistic time scales.

Efficiency of Ontario primary care physicians across payment models: a stochastic frontier analysis.

ObjectiveThe study examines the relationship between the primary care model that a physician belongs to and the efficiency of the primary care physician in Ontario, Canada.MethodsSurvey data were collected from 183 self-selected physicians and linked to administrative databases to capture the provision of services to the patients served for the 12 month period ending June 30, 2013, and the characteristics of the patients at the beginning of the study period. Two stochastic frontier regression models were used to estimate efficiency scores and parameters for two separate outputs: the number of distinct patients seen and the number of visits.ResultsBecause of missing data, only 165 physicians were included in the analyses. The average efficiency was 0.72 for both outputs with scores varying from 4 % to 93 % for the visits and 5 % to 94 % for the number of patients seen. We observed that there were both very low and very high efficiency scores within each model. These variations were larger than variations in average scores across models.

Functional Identification of Distinct Subpopulations of PreBötzinger Complex Neurons Regulating Separate Respiratory Motor Outputs

RationaleBreathing is an autonomic behaviour generated by a complex respiratory network in the brainstem. At its core is the preBötzinger Complex (preBötC), a population of neurons producing rhythmic breathing by activating respiratory muscles. The preBötC contains interneurons generating rhythmic respiratory activity, but also preBötC neurons that project to the hypoglossal premotor area, and then to the motor pool to activate the genioglossus muscle, an important upper airway respiratory muscle. The preBötC therefore regulates two distinct components of respiratory activity: rhythmic breathing and upper airway muscle activity. The anatomical organization of preBötC neurons is complex. The inhibitory peptide somatostatin (SST) is found in small fusiform interneurons expressing neurokinin‐1 receptors (small NK‐1R/SST neurons). SST is also co‐expressed with NK‐1Rs in medium‐size neurons that project to the hypoglossal premotor neurons (medium NK‐1R/SST neurons). A subpopulation of large multipolar preBötC neurons express NK‐1R, but not SST (NK‐1R neurons). The functional roles of these three subpopulations in mediating rhythmic breathing and upper airway muscle activity are unknown. Furthermore, NK‐1R and SST receptors can excite or inhibit neuronal activity through G‐protein‐gated inwardly rectifying potassium (GIRK) channels, but the contribution of these channels to SST and NK‐1R modulation of rhythmic breathing and upper airway muscle activity is not known.ObjectivesHere, we propose that GIRK channels play distinct functional roles in these three subpopulations of preBötC neurons. To test this claim, we probed the contributions of SST, NK‐1Rs and GIRK channels to rhythmic breathing and genioglossus muscle activity.MethodsWe microperfused selected agents into the preBötC of adult anesthetized rats and mice (wild‐type and GIRK2 subunit knockout; GIRK2−/−) while recording diaphragm and genioglossus muscle activity.ResultsSST (200 μM) decreased rhythmic breathing and genioglossus muscle activity. SST inhibition of rhythmic breathing, but not genioglossus muscle activity, was blocked by the SST 2A receptor antagonist CYN‐154806 (20 μM). The NK‐1R agonist GR73632 (50 μM) increased rhythmic breathing and genioglossus muscle activity. GIRK channel activation by flupirtine (100 μM) decreased rhythmic activity and genioglossus muscle activity in adult rats and wild‐type mice, but not in GIRK2−/− mice, suggesting that GIRK channels contribute to NK‐1R excitation. On the other hand, SST inhibition of rhythmic breathing was not blocked by the GIRK channel blocker Tertiapin Q (1 μM) and SST inhibition was observed both in wild‐type and GIRK2−/− mice.DiscussionNK1‐Rs regulate rhythmic breathing by acting through GIRK channels likely in small NK‐1R/SST neurons, and increase genioglossus muscle activity through GIRK channels possibly in large NK‐1R neurons. SST inhibits medium‐size NK‐1R/SST neurons and therefore reduce rhythmic breathing and genioglossus muscle activity through an unknown GIRK‐independent mechanism. Here, the functional roles of specific subpopulations of preBötC neurons were dissected by identifying the contribution of GIRK channels to two distinct respiratory behaviors.Support or Funding InformationG.M. was supported by a Parker B. Francis Fellowship.R.L.H was supported by a Tier 1 Canada Research Chair.This research was supported by the Canadian Institutes for Health Research (R.L.H.), the National Sanitarium Association Innovative Research Program (R.L.H.), and Canadian Institutes of Health Research (R.L.H.).

The research of laser crystal length impact on the self-Raman dual-wave length lasers output characteristics

Abstract In this work, the loss item of fundamental photon number which caused by the Raman effect is introduced into the rate equation of the fundamental laser, basing on this, the couple equations of self-Raman dual-wavelength continuous wave lasers is constructed. Through the solution of these equations, we achieved the expressions of output power of fundamental and Raman laser respectively and numerically simulated the output characteristics under the condition of different crystal length, including the separate output power, total output power and the ratio of two different wave lengths and deeply analyzed the physical mechanism under different output characteristics. The results show that crystal length of fundamental and Raman lasers are directly relevant to the characteristics of output, in which the former has minimally effect and the latter has maximally effect on it.

Disturbance Decoupling of Singular Boolean Control Networks.

This paper investigates the controller designing for disturbance decoupling problem (DDP) of singular Boolean control networks (SBCNs). Using semi-tensor product (STP) of matrices and the Implicit Function Theorem, a SBCN is converted into the standard BCN. Based on the redundant variable separation technique, both state feedback and output feedback controllers are designed to solve the DDP of the SBCN. Sufficient conditions are also given to analyze the invariance of controllers concerning the DDP of the SBCN with function perturbation. Two illustrative examples are presented to support the effectiveness of these obtained results.

THE NEW SCHEME EFFECTIVE GAS-STEAM INSTALLATION

The article describes the most common design of gas turbine units operated in a wide range of performance characteristics and climatic conditions. The advantages and disadvantages schematics of gas-steam units. The description of the new scheme of gas turbine installations in which the working process is carried out in two flow-through units of power gas turbines, partially combined, with separate outputs gases. Steam is generated in the output stream of one flow-through part of the installation and is supplied to the flow path of the other energy gas turbine power plant. Shown that increases the effective efficiency of the plant increases capacity. Thermal scheme of the GPU designed to meet modern environmental requirements. Observed that the question whether the capture is introduced into the combustion chamber water vapor does not have a universal solution and is determined by the specific working conditions of newly built or renovated power station.

Microwave Chip-Based Beam Splitter for Low-Energy Guided Electrons.

We present a novel beam splitter for low-energy electrons using a micro-structured guiding potential created above the surface of a planar microwave chip. Beam splitting arises from smoothly transforming the transverse guiding potential for an electron beam from a single-well harmonic confinement into a double well, thereby generating two separated output beams with 5mm lateral spacing. Efficient beam splitting is observed for electron kinetic energies up to 3eV, in excellent agreement with particle tracking simulations. We discuss prospects of this novel beam splitter approach for electron-based quantum matter-wave optics experiments.

Dual-function photonic integrated circuit for frequency octo-tupling or single-side-band modulation.

A dual-function photonic integrated circuit for microwave photonic applications is proposed. The circuit consists of four linear electro-optic phase modulators connected optically in parallel within a generalized Mach-Zehnder interferometer architecture. The photonic circuit is arranged to have two separate output ports. A first port provides frequency up-conversion of a microwave signal from the electrical to the optical domain; equivalently single-side-band modulation. A second port provides tunable millimeter wave carriers by frequency octo-tupling of an appropriate amplitude RF carrier. The circuit exploits the intrinsic relative phases between the ports of multi-mode interference couplers to provide substantially all the static optical phases needed. The operation of the proposed dual-function photonic integrated circuit is verified by computer simulations. The performance of the frequency octo-tupling and up-conversion functions is analyzed in terms of the electrical signal to harmonic distortion ratio and the optical single side band to unwanted harmonics ratio, respectively.

CW dual-frequency MOPA laser with frequency separation of 45 GHz.

A CW dual-frequency master oscillator power amplifier (MOPA) laser system with dozens of gigahertz (GHz) frequency separation is presented. The MOPA system consists of a monolithic microchip seed laser and a double-end pumped traveling wave power amplifier. The short length of seed laser cavity guarantees the seed signal with a large frequency separation (above 53 GHz) but low output power (below 247.8 mW). By adding a long and low-doped active medium laser amplifier stage, a significant increase in laser power and an improvement in beam quality are obtained. After fine temperature tuning of seed laser cavity for "spectra matching", a 2.40 W dual-frequency laser signal with 45 GHz frequency separation is achieved.

Identifying the challenges of creating an optimal dissemination geography for census

The importance of census data in government and private-sector planning cannot be underestimated. However, the geographic level at which it is made available for different users, is a highly debateable issue. It is crucial that census data is disseminated in such a way that it satisfies most user needs as far as possible, to ensure that there is optimum use of the information and that maximum value for money is provided. In the past, Statistics South Africa disseminated data at the same geographic level created for data collection. This causes problems for data users and calls for the creation of a separate output geography rather than using the original collection geography.The research was done on two levels: first, an overview of output geographies, as well as examples of developed and successfully used tools to generate these areas within a geographical information system. Some of these could be used in the South African milieu. Secondly the paper discuss aspects such as the population size variation of EAs, in order to inform the criteria for the creation of the ideal small area (SA) layer to satisfy the majority of user needs. Lastly the paper describes briefly the challenges faced to create the 2011 output geography. The results indicate a strong resemblance between the two EA population size patterns of 2001 and 2011, influenced by the EA demarcation rules. The challenges identified in the process of creating the SAL as a census output geography need to be taken into consideration to enable a more useful and user-friendly output.

A Post-filtering Algorithm for Crosstalk Subtraction in Blind Speech Separation Outputs

In this paper, exclusive activity periods (EAPs) are used to model crosstalks in which only one blind source separation (BSS) output signal is assumed to be active and the others are inactive. Inactive intervals of each EAP are used to estimate the crosstalk leaked from each active signal using a least squares method. Then, we use the Wiener filter to cancel the estimated crosstalks from BSS outputs. The benefit of using EAPs is to simplify the estimation of crosstalks from all other signals to the estimation of them from just one active signal in each interval. Thus, it leads to estimate and suppress crosstalks more precisely. A comparison of our method with other popular post-processing algorithms is drawn. The results show an improved performance of the proposed method over earlier approaches.

Kickback Cuts Backprop's Red-Tape: Biologically Plausible Credit Assignment in Neural Networks

Error backpropagation is an extremely effective algorithm for assigning credit in artificial neural networks. However, weight updates under Backprop depend on lengthy recursive computations and require separate output and error messages — features not shared by biological neurons, that are perhaps unnecessary. In this paper, we revisit Backprop and the credit assignment problem. We first decompose Backprop into a collection of interacting learning algorithms; provide regret bounds on the performance of these sub-algorithms; and factorize Backprop's error signals. Using these results, we derive a new credit assignment algorithm for nonparametric regression, Kickback, that is significantly simpler than Backprop. Finally, we provide a sufficient condition for Kickback to follow error gradients, and show that Kickback matches Backprop's performance on real-world regression benchmarks.

Phosphate sink containing two-component signaling systems as tunable threshold devices.

Synthetic biology aims to design de novo biological systems and reengineer existing ones. These efforts have mostly focused on transcriptional circuits, with reengineering of signaling circuits hampered by limited understanding of their systems dynamics and experimental challenges. Bacterial two-component signaling systems offer a rich diversity of sensory systems that are built around a core phosphotransfer reaction between histidine kinases and their output response regulator proteins, and thus are a good target for reengineering through synthetic biology. Here, we explore the signal-response relationship arising from a specific motif found in two-component signaling. In this motif, a single histidine kinase (HK) phosphotransfers reversibly to two separate output response regulator (RR) proteins. We show that, under the experimentally observed parameters from bacteria and yeast, this motif not only allows rapid signal termination, whereby one of the RRs acts as a phosphate sink towards the other RR (i.e. the output RR), but also implements a sigmoidal signal-response relationship. We identify two mathematical conditions on system parameters that are necessary for sigmoidal signal-response relationships and define key parameters that control threshold levels and sensitivity of the signal-response curve. We confirm these findings experimentally, by in vitro reconstitution of the one HK-two RR motif found in the Sinorhizobium meliloti chemotaxis pathway and measuring the resulting signal-response curve. We find that the level of sigmoidality in this system can be experimentally controlled by the presence of the sink RR, and also through an auxiliary protein that is shown to bind to the HK (yielding Hill coefficients of above 7). These findings show that the one HK-two RR motif allows bacteria and yeast to implement tunable switch-like signal processing and provides an ideal basis for developing threshold devices for synthetic biology applications.

Design methodology of a six-component balance for measuring forces and moments in water tunnel tests

This article describes the methodology used in the design and evaluation of a new, six-component balance. This balance is used to measure the forces and moments in model tests conducted in the water tunnel at the Iran University of Science & Technology (IUST). To design the structural parameters of the balance, were used derived equations as well as the finite element method in an iterative process. At every step in this process, the dimensions obtained from the derived equations were determined by considering the nominal strain. The finite element method was used to demonstrate the manner in which the strain was distributed and the reliability of the quantities obtained from the derived equations. To evaluate the designed balance, the strain distribution, linearity, stiffness, and the balance’s ability to produce separate component outputs were investigated. The results that were obtained indicating that the designed structure satisfied all the design criteria. A first-order model was used to calibrate the balance. The evaluation of the sensitivity matrix showed that the error that resulted from the effects of the non-linearity associated with the applied loads was less than 0.05%.

Simultaneous purification and fractionation of nucleic acids and proteins from complex samples using bidirectional isotachophoresis.

We report on our efforts to create an on-chip system to simultaneously purify and fractionate nucleic acids and proteins from complex samples using isotachophoresis (ITP). We have developed this technique to simultaneously extract extracellular DNA and proteins from human blood serum samples and deliver these to two separate output reservoirs on a chip. The purified DNA is compatible with quantitative polymerase chain reaction (qPCR), and proteins can be extracted so as to exclude albumin, the most abundant protein in serum. We describe significant remaining challenges in making this bidirectional method a robust and efficient technique. These challenges include managing channel surface adsorption of proteins, identifying the cause of observed reductions in low molecular weight proteins, and dealing with nonspecific binding of proteins and DNA.

Repetitive Control for High-Performance Resonant Pulsed Power Supply in Radio Frequency Applications

This paper presents a novel three phase series resonant parallel loaded (SRPL) resonant converter topology for radio frequency (RF) applications. The proposed converter is capable to produce as output voltage a series of “long pulses”, each one lasting 1ms in time. Three individual single phase resonant stages are able to operate independently in conjunction with three separate single phase output rectification stages. Due to this important feature, the converter has a strong ability of rejecting the influence of unbalance in the resonant tanks. A PI + Repetitive Control (RC) strategy has been used for the output pulsed voltage regulation, resulting in a fast rise time, reduced overshoot, and constant amplitude. The soft-switching of semiconductor devices is ensured at full power by a combined frequency and phase shift modulation (CFPS), even in the presence of large tank unbalances.

Monolithic integration of a quantum emitter with a compact on-chip beam-splitter

A fundamental component of an integrated quantum optical circuit is an on-chip beam-splitter operating at the single-photon level. Here, we demonstrate the monolithic integration of an on-demand quantum emitter in the form of a single self-assembled InGaAs quantum dot (QD) with a compact (>10 μm), air clad, free standing directional coupler acting as a beam-splitter for anti-bunched light. The device was tested by using single photons emitted by a QD embedded in one of the input arms of the device. We verified the single-photon nature of the QD signal by performing Hanbury Brown-Twiss measurements and demonstrated single-photon beam splitting by cross-correlating the signal from the separate output ports of the directional coupler.

A study on the role of transmittances effect the self-Raman dual-wavelength laser output characteristics

In this work, the coupled equations of self-Raman dual-wavelength continuous-wave lasers are constructed by introducing the loss item of fundamental photon number. The output power analytical expressions of the fundamental laser and Raman laser are obtained through solving the couple equations. The impaction of transmittances on the self-Raman dual-wavelength laser output characteristics are simulated. Under different transmittance combination conditions, the changing rules of the separate output power, total output power and the ratio of two different wavelengths output power are given. The coupled equations are solved in approximations such as plane wave and independent-space intensity distribution, however the simulated results can show the main tendency of self-Raman dual-wavelength continuous-wave lasers, this has a certain guiding significance for the experiment.

Parvalbumin-positive basket cells differentiate among hippocampal pyramidal cells.

CA1 pyramidal cells (PCs) are not homogeneous but rather can be grouped by molecular, morphological, and functional properties. However, less is known about synaptic sources differentiating PCs. Using paired recordings in vitro, two-photon Ca(2+) imaging in vivo, and computational modeling, we found that parvalbumin-expressing basket cells (PVBCs) evoked greater inhibition in CA1 PCs located in the deep compared to superficial layer of stratum pyramidale. In turn, analysis of reciprocal connectivity revealed more frequent excitatory inputs to PVBCs by superficial PCs, demonstrating bias in target selection by both the excitatory and inhibitory local connections in CA1. Additionally, PVBCs further segregated among deep PCs, preferentially innervating the amygdala-projecting PCs but receiving preferential excitation from the prefrontal cortex-projecting PCs, thus revealing distinct perisomatic inhibitory interactions between separate output channels. These results demonstrate the presence of heterogeneous PVBC-PC microcircuits, potentially contributing to the sparse and distributed structure of hippocampal network activity.

Heterogeneous Farm Output and Technical Efficiency Estimates

Farmers in most OECD countries are engaged in different activities which go beyond agriculture. When assessing farm performance, it is appropriate to model these heterogeneous farm outputs separately. In this study, we use the distance function approach, which allows the consideration of technology with multiple outputs and multiple inputs. We compare estimates from single-output technology with estimates from multiple- output technology. Our empirical analysis is based on an unbalanced panel of dairy farms in the plain region of Switzerland for the period from 2003 to 2009. We choose the parametric estimation method and employ a translog specification of the production technology. The test of output separability favours a model that separately considers three different outputs: agricultural output; para-agricultural output; and direct payments. The separate modelling of direct payments has considerable influence on the estimated technology parameters as well as the technical efficiency scores. The consideration of direct payments as a separate output increases the elasticity of land by a factor greater than two and, accordingly, reduces the distance function elasticities of other inputs. The average technical efficiency estimates do not differ substantially when specifications differ. However, we reveal serious differences in the estimates of technical efficiency for individual farms. The estimated rank correlation coefficients show that the ranking of farms in terms of technical efficiency differs considerably when direct payments are modelled as a separate output.