Parallel Integration Research Articles

Swarm-NG: A CUDA library for Parallel n-body Integrations with focus on simulations of planetary systems

We present Swarm-NG, a C++ library for the efficient direct integration of many n-body systems using a Graphics Processing Unit (GPU), such as NVIDIA’s Tesla T10 and M2070 GPUs. While previous studies have demonstrated the benefit of GPUs for n-body simulations with thousands to millions of bodies, Swarm-NG focuses on many few-body systems, e.g., thousands of systems with 3…15 bodies each, as is typical for the study of planetary systems. Swarm-NG parallelizes the simulation, including both the numerical integration of the equations of motion and the evaluation of forces using NVIDIA’s “Compute Unified Device Architecture” (CUDA) on the GPU. Swarm-NG includes optimized implementations of 4th order time-symmetrized Hermite integration and mixed variable symplectic integration, as well as several sample codes for other algorithms to illustrate how non-CUDA-savvy users may themselves introduce customized integrators into the Swarm-NG framework. To optimize performance, we analyze the effect of GPU-specific parameters on performance under double precision. For an ensemble of 131072 planetary systems, each containing three bodies, the NVIDIATesla M2070 GPU outperforms a 6-core Intel Xeon X5675 CPU by a factor of ∼2.75. Thus, we conclude that modern GPUs offer an attractive alternative to a cluster of CPUs for the integration of an ensemble of many few-body systems.Applications of Swarm-NG include studying the late stages of planet formation, testing the stability of planetary systems and evaluating the goodness-of-fit between many planetary system models and observations of extrasolar planet host stars (e.g., radial velocity, astrometry, transit timing). While Swarm-NG focuses on the parallel integration of many planetary systems, the underlying integrators could be applied to a wide variety of problems that require repeatedly integrating a set of ordinary differential equations many times using different initial conditions and/or parameter values.

Mathematics as (Multi)cultural Practice: Irish Lessons From the Polish Weekend School

In this article, the authors challenge the erroneous assumption that mathematics is universal, and thus culturally neutral, by critically investigating diverse cultural meanings and “ways of knowing” that influence individual/social (affective) forms of identity. The authors begin by briefly detailing the structural features of a Polish weekend school and providing an overview profile of the Polish community living in Ireland. The rationale for the “weekend” school is then discussed from both Polish and Irish perspectives. Empirical data suggest a greater need for “parallel integration,” whereby two divergent education systems attempt to culturally coalesce at some level of school policy and/or mathematics classroom practice.

Psychotherapy and rehabilitation for schizophrenia: Thoughts about their parallel development and potential integration.

Psychotherapy and rehabilitation for schizophrenia: Thoughts about their parallel development and potential integration.

Conscious Attention, Meditation, and Bilateral Information Transfer

Recent findings indicate that conscious attention is related to large-scale information integration of various brain regions, including both hemispheres, that enables integration of parallel distributed modalities of processed information. There is also evidence that the level of information transference related to integration or splitting among brain regions, and between hemispheres, establishes a certain level of efficiency of the information processing. The level of information transference also may have modulatory influences on attentional capacity that are closely linked to the emotional arousal and autonomic response related to a stimulus. These findings suggest a hypothesis that changes in conscious attention, specifically during meditation could be reflected in the autonomic activity as the left-right information transference calculated from bilateral electrodermal activity (EDA). With the aim to compare conscious attention during meditation with other attentional states (resting state, Stroop task, and memory task), we performed bilateral EDA measurement in 7 healthy persons during resting state, Stroop task, neurofeedback memory test, and meditation. The results indicate that the information transference (ie, transinformation) is able to distinguish those attentional states, and that the highest level of the transinformation has been found during attentional processing related to meditation, indicating higher level of connectivity between left and right sides. Calculations other than pointwise transinformation (PTI) performed on EDA records, such as mean skin conductance level or laterality index, were not able to distinguish attentional states. The results suggest that PTI may present an interesting method useful for the assessment of information flow, related to neural functioning, that in the case of meditation may reflect typical integrative changes in the autonomic nervous system related to brain functions and focused attentional processing.

Integration of early identification and brief intervention in frontline health services: the case of Quebec

In 2006, the Quebec provincial government committed itself to developing capacity for evidence-based alcohol and other drug screening and brief intervention (SBI) in frontline health-service delivery settings. Two studies were conducted prior to province-wide deployment to inform decision makers as to possible implementation challenges. Study 1 evaluated the efficacy of implementing a model of SBI, adapted from the World Health Organization, in three frontline public health services. Sixty-two clinicians were trained in systematic detection of substance use and brief motivational intervention. Chart review of new admissions (N = 453) prior and following training assessed clinician conformity to SBI guidelines. Forty percent of patients endorsed at least one item on the four-question CAGE-AID (Cut Down, Annoyed, Guilty, Eye Opener screen Adapted to Include Drugs). Systematic screening among new admissions peaked at 70% and decreased to pre-training levels seven months after training. However, more than half of all new patients were assessed with validated questionnaires rather than informal questioning. Implementation of motivational interviewing techniques led to modest changes in clinician interventions. A second qualitative study was conducted to document possible organizational barriers to SBI implementation. Interviews were conducted with 24 clinicians and program administrators from frontline services of the six main health regions of Quebec province. Choice of vocabulary used in public policy documents and program material and sequence of delivery of services created confusion among clinicians as to what constituted alcohol and other drug SBI. Many resources developed for other SBI health programs in these frontline services seemed to be transferable to alcohol and drug SBI. Lessons learned were as follows: complexity in the SBI program is inversely related to the subsequent integrity of program deployment; clarity as to what constitutes SBI is paramount; and integration of parallel competencies/related programs could facilitate deployment of alcohol and other drug SBI.

Some investigations on fuzzy P + fuzzy I + fuzzy D controller for non-stationary process

The paper addresses the adaptive behaviour of parallel fuzzy proportional plus fuzzy integral plus fuzzy derivative (FP+FI+FD) controller. The parallel FP+FI+FD controller is actually a non-linear adaptive controller whose gain changes continuously with output of the process under control. Two non-stationary processes, whose characteristics change with time, are considered for simulation study. Simulation is performed using software LabVIEW?. The set-point tracking response of parallel FP+FI+FD is compared with conventional parallel proportional plus integral plus derivative (PID) controller, tuned with the Ziegler-Nichols (Z-N) tuning technique. Simulation results show that conventional PID controller fails to track the set-point and becomes unstable as the process changes its characteristic with time. But the parallel FP+FI+FD controller shows considerably much better set-point tracking response and does not deviate from steady state. Also, a huge spike is observed in the output of PID controller as the reference set-point and process parameters are changed, while the FP+FI+FD controller gives spike free control signal.

Spike-Timing-Dependent Plasticity With Weight Dependence Evoked From Physical Constraints

Analogue and mixed-signal VLSI implementations of Spike-Timing-Dependent Plasticity (STDP) are reviewed. A circuit is presented with a compact implementation of STDP suitable for parallel integration in large synaptic arrays. In contrast to previously published circuits, it uses the limitations of the silicon substrate to achieve various forms and degrees of weight dependence of STDP. It also uses reverse-biased transistors to reduce leakage from a capacitance representing weight. Chip results are presented showing: various ways in which the learning rule may be shaped; how synaptic weights may retain some indication of their learned values over periods of minutes; and how distributions of weights for synapses convergent on single neurons may shift between more or less extreme bimodality according to the strength of correlational cues in their inputs.

Laser-assisted nanofabrication of carbon nanostructures

An overview of laser-assisted techniques developed in our group for fabricating carbon nanostructures, including two-dimensional graphene, one-dimensional carbon nanotubes, and zero-dimensional carbon nanoonions, is presented. Unique laser-material interactions provide versatile possibilities in fabricating carbon nanostructures, including localized heating, direct laser writing, tip-enhanced optical near-field effect, polarization, ablation, resonant excitation, precise energy delivery, and mask-free direct patterning. Rapid single-step fabrication of graphene patterns was achieved using laser directing writing. Parallel integration of single-walled carbon nanotubes was realized by making use of tip-enhanced optical near-field effect. High-quality carbon nanoonions were obtained through laser resonant excitation of precursor molecules.

Affective Learning: Empathetic Agents with Emotional Facial and Tone of Voice Expressions

Empathetic behavior has been suggested to be one effective way for Embodied Conversational Agents (ECAs) to provide feedback to learners' emotions. An issue that has been raised is the effective integration of parallel and reactive empathy. The aim of this study is to examine the impact of ECAs' emotional facial and tone of voice expressions combined with empathetic verbal behavior when displayed as feedback to students' fear, sad, and happy emotions in the context of a self-assessment test. Three identical female agents were used for this experiment: 1) an ECA performing parallel empathy combined with neutral emotional expressions, 2) an ECA performing parallel empathy displaying emotional expressions that were relevant to the emotional state of the student, and 3) an ECA performing parallel empathy by displaying relevant emotional expressions followed by emotional expressions of reactive empathy with the goal of altering the student's emotional state. Results indicate that an agent performing parallel empathy displaying emotional expressions relevant to the emotional state of the student may cause this emotion to persist. Moreover, the agent performing parallel and then reactive empathy appeared to be effective in altering an emotional state of fear to a neutral one.

Localized Netrins Act as Positional Cues to Control Layer-Specific Targeting of Photoreceptor Axons in Drosophila

SummaryA shared feature of many neural circuits is their organization into synaptic layers. However, the mechanisms that direct neurites to distinct layers remain poorly understood. We identified a central role for Netrins and their receptor Frazzled in mediating layer-specific axon targeting in the Drosophila visual system. Frazzled is expressed and cell autonomously required in R8 photoreceptors for directing their axons to the medulla-neuropil layer M3. Netrin-B is specifically localized in this layer owing to axonal release by lamina neurons L3 and capture by target neuron-associated Frazzled. Ligand expression in L3 is sufficient to rescue R8 axon-targeting defects of Netrin mutants. R8 axons target normally despite replacement of diffusible Netrin-B by membrane-tethered ligands. Finally, Netrin localization is instructive because expression in ectopic layers can retarget R8 axons. We propose that provision of localized chemoattractants by intermediate target neurons represents a highly precise strategy to direct axons to a positionally defined layer.

Suspension Culture of Human Pluripotent Stem Cells in Controlled, Stirred Bioreactors

Therapeutic and industrial applications of pluripotent stem cells and their derivatives require large cell quantities generated in defined conditions. To this end, we have translated single cell-inoculated suspension cultures of human pluripotent stem cells (hPSCs; including human induced pluripotent stem cells [hiPS] and human embryonic stem cells [hESC]) to stirred tank bioreactors. These systems that are widely used in biopharmaceutical industry allow straightforward scale up and detailed online monitoring of key process parameters. To ensure minimum medium consumption, but in parallel functional integration of all probes mandatory for process monitoring, that is, for pO₂ and pH, experiments were performed in 100 mL culture volume in a "mini reactor platform" consisting of four independently controlled vessels. By establishing defined parameters for tightly controlled cell inoculation and aggregate formation up to 2×10⁸ hiPSCs/100 mL were generated in a single process run in 7 days. Expression of pluripotency markers and ability of cells to differentiate into derivates of all three germ layers in vitro was maintained, underlining practical utility of this new process. The presented data provide key steps toward scalable mass expansion of human iPS and ES cells thereby enabling translation of stem cell research to (pre)clinical application in relevant large animal models and valuable in vitro assays for drug development and validation as well.

Single crystal silicon nanopillars, nanoneedles and nanoblades with precise positioning for massively parallel nanoscale device integration

Arrays of precisely positioned single crystal silicon nanopillars, nanoneedles, and nanoblades with minimum feature sizes as small as 30 nm are fabricated using entirely scalable top-down fabrication techniques. Using the same scalable technologies, devices consisting of electrically connected silicon nanopillars with multiple addressable electrodes for each nanostructure are realized. The arrays of nanopillars, nanoneedles, and nanoblades are shown to exhibit Raman signal enhancement on 1,2-benzenedithiol monolayers, opening a path to nanodevices that manipulate, position, detect and analyze molecules.

Spatial localization and projection densities of brainstem mossy fibre afferents to the forelimb C1 zone of the rat cerebellum.

The present study uses a double retrograde tracer technique in rats to examine the spatial localization and pattern of axonal branching in mossy fibres arising from three major sources in the medulla-the external cuneate nucleus, the sensory trigeminal nucleus and the reticular formation, to two electrophysiologically-identified parts of the cerebellar cortex that are linked by common climbing fibre input - the forelimb-receiving parts of the C1 zone in lobulus simplex and the paramedian lobule. In each experiment a small injection of rhodamine-tagged beads was injected into one cortical region and an injection of fluorescein-tagged beads was injected into the other region. The main findings were: (i) the proportion of double-labelled cells in each of the three precerebeller sources of mossy fibres was positively correlated with those in the inferior olive; and (ii) the C1 zone in lobulus simplex was found to receive a greater density of projections from all three sources of mossy fibres than the C1 zone in the paramedian lobule. These data suggest that two rostrocaudally separated but somatotopically corresponding parts of the C1 zone receive common mossy fibre and climbing fibre inputs. However, the differences in projection densities also suggest that the two parts of the zone differ in the extent to which they receive mossy fibre signals arising from the same precerebellar nuclei. This implies differences in function between somatotopically corresponding parts of the same cortical zone, and could enable a higher degree of parallel processing and integration of information within them.

Real Time Parallel Intraoperative Integration of Endoscopic, Microscopic, and Navigation Images: A Proof of Concept Based on Laboratory Dissections

Endoscope, microscope, and neuronavigation systems are integrated in neurosurgical procedures mainly by using a serial combination algorithm, where, the user must switch his/her field of view from one platform display to another. The integration of theses devices could be optimized by incorporating different displays into one viewing platform thus achieving a parallel combination. In this study, we investigated the feasibility and the applicability of parallel integration of microscopic, endoscopic, and neuronavigation images by real time displaying the endoscope and neuronavigation image datasets in the main operative microscope oculars. The proposed set-up was effective in displaying the three images dataset in an operationally actionable mode. Ergonomically, the ability of using the different image dataset without the need of taking the eyes off the microscope oculars did not disrupt the flow or the tempo of the operative procedure. However, new endoscopes specific to this application are recommended.

An improved fuzzy cellular neural network (IFCNN) for an edge detection based on parallel RK(5,6) approach

Parallel RK(5,6) algorithms are employed to validate the potential behaviour under improved fuzzy cellular neural network paradigm for an edge detection problem is the novelty of this paper. The function of the simulator is capable of performing raster fuzzy cellular neural network simulation for any kind as well as any size of input image. The raster pseudo code exploits the latency properties of improved fuzzy cellular neural network coupled with different parallel numerical integration algorithms. Results provide a better understanding about single layer/raster behaviour simulation.

Computing overall elastic constants of polydisperse particulate composites from microtomographic data

In this paper, we use the well-known Hashin–Shtrikman–Willis variational principle to obtain the overall mechanical properties of heterogeneous polydisperse particulate composites. The emphasis is placed on the efficient numerical integration of complex three-dimensional integrals and on aspects of the anisotropic material response of real tomographically characterized packs. For this purpose, we numerically calculate the complete statistics of real packs, which are numerically or tomographically generated. We use the parallel adaptive sparse Smolyak integration method with hierarchical basis to integrate complex singular integrals containing the product of probability functions and the second derivative of Green's function. Selected examples illustrate both the numerical and physical facets of our work. First, we show the reduction of integral points for integration in spherical coordinates. Then, we comment on the parallel scalability of our method and on the numerical accuracy associated with the integration of a singular function. Next, we validate the solver against the experimental data and verify the results by comparing it to a closed-form expression. To investigate the ability of our scheme to capture the anisotropic nature of packs, we study a lattice type system. Finally, we report on the elastic constants computed for the modeled anisotropic particulate system that is tomographically characterized.

Surface-Tension Driven Heterogeneous Integration of Thin Film Photonic Devices Using Micro-Contact Printing for Multi-Material Photonic Integrated Circuits

We introduce a surface-tension driven heterogeneous integration of thin film photonic devices using a surface wetting modification. In this process, the combination of a micro-contact printing method and plasma surface modification is used to selectively form a binding liquid on an integration host substrate. With predefined integration areas using the binding liquid, thin film GaAs photodetectors (PDs) are successfully integrated. We have demonstrated the implementation of this integration method by presenting a multi-material photonic integrated structure with integrated GaAs based thin film PDs and a polymer waveguide on a silicon substrate. The measured average misalignment of the integrated PDs was 2.8 μ m from the predefined integration locations. Stable electrical contact between the PDs and the host substrate has been confirmed with dark and photocurrent measurements. The proposed process has the potential towards a low-cost, parallel heterogeneous integration of III-V photonic devices on a silicon platform.

Resolving a L2-prefetch-caused parallel nonscaling on Intel Core microarchitecture

Parallel workloads on shared-memory multi-core processors often suffer from performance degradation. Cache eviction, true/false sharing and bus contention are among the well-understood causes to this problem. This paper presents a study that shows the L2 DPL (data prefetch logic) in processors based on Intel Core microarchitecture can be a cause to this problem as well. The study through a case of an image integration finds the nonscaling problem on the parallel integration of images whose size exceeds the capacity of the processor’s L2 cache. Through an analysis on relevant performance events using Intel VTune™Performance Analyser the L2 DPL prefetch is found less effective over the parallel integration in prefetching needed data than over the serial ones. To resolve the problem a novel parallel image reverse loading is developed with the purpose of reducing the number of memory accesses over the parallel integration and the associated delay. Experimental results demonstrate that the parallel integration after the parallel reverse loading shows significant speedup against the same parallel integration but after serial loading.

QYMSYM: A GPU-accelerated hybrid symplectic integrator that permits close encounters

We describe a parallel hybrid symplectic integrator for planetary system integration that runs on a graphics processing unit (GPU). The integrator identifies close approaches between particles and switches from symplectic to Hermite algorithms for particles that require higher resolution integrations. The integrator is approximately as accurate as other hybrid symplectic integrators but is GPU accelerated.

L’identità europea

The problem of a distinctive European identity is both an interesting research question and a politically relevant issue. It is a complex and controversial research question for two main reasons: first, Europe has traditionally been an open and multiple world, with several cultural identities, which has constantly put into question its common beliefs and unifying ties – as a result, some scholars consider it more appropriate to speak of European identities in the plural. Second, the culture of Europe has become the culture of modernity and various basic components of the European identity have been globally diffused, making it difficult, to identify what is to-day specifically European. European identity is also a key political issue. There is widespread criticism that the European Union is today a limited project since the economic integration of Europe has not been transformed by a parallel cultural integration into a true political union. Actually, the current construction of the European Union- as a process of building a loosely coupled, open system through a set of supra-national, supra-state normative institutions- is made possible by a common historical heritage and by shared cultural attitudes. It is argued that there are both several different identities of the European peoples and a European common identity based on a set of common cultural roots that the advent of modernity had fixed into a specific cultural and institutional setting. The European project is still a modern project because its common identity must be constructed on the future, on the principle of the unity through the diversity denying the old belief that what is different is potentially hostile: iy may be weaker than traditional national identities, but is more apt to contribute to a democratic form of global governance.