Multiple Parallel Streams Research Articles

A Canonical Laminar Neocortical Circuit Whose Bottom-Up, Horizontal, and Top-Down Pathways Control Attention, Learning, and Prediction.

All perceptual and cognitive circuits in the human cerebral cortex are organized into layers. Specializations of a canonical laminar network of bottom-up, horizontal, and top-down pathways carry out multiple kinds of biological intelligence across different neocortical areas. This article describes what this canonical network is and notes that it can support processes as different as 3D vision and figure-ground perception; attentive category learning and decision-making; speech perception; and cognitive working memory (WM), planning, and prediction. These processes take place within and between multiple parallel cortical streams that obey computationally complementary laws. The interstream interactions that are needed to overcome these complementary deficiencies mix cell properties so thoroughly that some authors have noted the difficulty of determining what exactly constitutes a cortical stream and the differences between streams. The models summarized herein explain how these complementary properties arise, and how their interstream interactions overcome their computational deficiencies to support effective goal-oriented behaviors.

The Role of Analysis Error in the Convergence of Reanalysis Production Streams in MERRA-2

ABSTRACTDue to production time constraints, most reanalyses are produced in multiple parallel streams instead of a single continuous one. These streams cover separate segments of the reanalysis time period with short overlaps to allow reconstruction of the official record. A fundamental assumption justifying this approach is that the streams will be assimilating the same observations during the periods where they overlap, and so will eventually converge to a similar atmospheric state, making discontinuities at stream junctions negligible. This assumption is revisited in this work by examining the impact of analysis error on the differences between MERRA-2 overlapping streams in three historical periods. Comparison results are shown in terms of standard deviations of stream differences as well as the spectral decomposition of the variance of their differences. Residual differences were found at the end of each year of overlap, with larger values observed in the earlier segments of the presatellite era. By drawing parallels with analysis error statistics estimated from the GMAO OSSE system, these differences are shown to reflect the varying constraint of data with the varying observing network, and to further carry the imprint of errors that the data assimilation process is not able to mitigate. As such, they are unlikely to be reduced by longer spinup periods. The ability of data assimilation to ensure continuity in the parallel streams is put into question when the observing system coverage is inadequate or simply when the data assimilation system as a whole is suboptimal.

Biased synaptopathy as a central mechanism of age-related hearing loss.

Biased synaptopathy as a central mechanism of age-related hearing loss.

Control structures for process piping systems

Many chemical processes require complex piping configurations to achieve a variety of objectives such as splitting a stream into multiple parallel streams, blending several streams, bypassing units and interconnecting process units. The plumbing required for effective fluid-mechanics performance and the control structure required for effective dynamic control differ from case to case. Liquid streams need to be handled in a different manner than vapor streams because their incompressibility prohibits having two control valves in series. This paper presents several important examples of process piping configurations and practical control structures for achieving good performance.

Performance Analysis of SCTP for Multiple Parallel Streams

SCTP is a connection oriented general purpose transport protocol and applications presented in the transport layer for concept of streams. Different streams provide multiple end to end connections that enables independent send and receiver buffer at two end points. In this paper we performed performance measurement for simultaneous parallel streams. Performance of SCTP is closely examined for two parallel streams and considerable improvement of bandwidth utilization observed as compared to single stream

Gradients in predation risk in a tropical river system.

The importance of predation risk as a key driver of evolutionary change is exemplified by the Northern Range in Trinidad, where research on guppies living in multiple parallel streams has provided invaluable insights into the process of evolution by natural selection. Although Trinidadian guppies are now a textbook example of evolution in action, studies have generally categorized predation as a dichotomous variable, representing high or low risk. Yet, ecologists appreciate that community structure and the attendant predation risk vary substantially over space and time. Here, we use data from a longitudinal study of fish assemblages at 16 different sites in the Northern Range to quantify temporal and spatial variation in predation risk. Specifically we ask: 1) Is there evidence for a gradient in predation risk? 2) Does the ranking of sites (by risk) change with the definition of the predator community (in terms of species composition and abundance currency), and 3) Are site rankings consistent over time? We find compelling evidence that sites lie along a continuum of risk. However, site rankings along this gradient depend on how predation is quantified in terms of the species considered to be predators and the abundance currency is used. Nonetheless, for a given categorization and currency, rankings are relatively consistent over time. Our study suggests that consideration of predation gradients will lead to a more nuanced understanding of the role of predation risk in behavioral and evolutionary ecology. It also emphasizes the need to justify and report the definition of predation risk being used.

Magnetic Induction-Based Simultaneous Wireless Information and Power Transfer for Single Information and Multiple Power Receivers

Magnetic induction (MI)-based communication systems have gained increased attention in recent years. Typical applications for these systems lie in the area of wireless power transfer, near-field communication (NFC), and wireless sensor networks in challenging environments. In this paper, a system for simultaneous wireless information and power transfer (SWIPT) using MI-based signal transmission is designed for supporting one data stream and multiple parallel power streams. One of the possible applications for this scheme is an NFC-based access point. The overall system is optimized to guarantee a certain quality-of-service for the data stream as well as a maximum sum receive power for all power receivers (max-sum problem) or a maximum receive power for the worst power receiver (max-min problem), respectively. Both optimization problems turn out to be non-convex, such that the optimum solution cannot be found with limited computational complexity. Hence, we provide efficient suboptimal solutions. In this context, a convex approximation of the transmit power constraint in MI-based multiple-input multiple-output systems turns out to be very useful. A very high achievable power efficiency renders the proposed MI-based SWIPT system very promising.

Optimized Adaptive Streaming of Multi-video Stream Bundles

In contrast to traditional video, multi-view video streaming allows viewers to interactively switch among multiple perspectives provided by different cameras. One approach to achieve such a service is to encode the video from all of the cameras into a single stream, but this has the disadvantage that only a portion of the received video data will be used, namely that required for the selected view at each point in time. In this paper, we introduce the concept of a “multi-video stream bundle” that consists of multiple parallel video streams that are synchronized in time, each providing the video from a different camera capturing the same event or movie. For delivery we leverage the adaptive features and time-based chunking of HTTP-based adaptive streaming, but now employing adaptation in both content and rate. Users are able to change their viewpoint on-demand and the client player adapts the rate at which data are retrieved from each stream based on the user's current view, the probabilities of switching to other views, and the user's current bandwidth conditions. A crucial component of such a system is the prefetching policy. For this we present an optimization model as well as a simpler heuristic that can balance the playback quality and the probability of playback interruptions. After analytically and numerically characterizing the optimal solution, we present a prototype implementation and sample results. Our prefetching and buffer management solution is shown to provide close to seamless playback switching when there is sufficient bandwidth to prefetch the parallel streams.

Principles of structure building in music, language and animal song.

Human language, music and a variety of animal vocalizations constitute ways of sonic communication that exhibit remarkable structural complexity. While the complexities of language and possible parallels in animal communication have been discussed intensively, reflections on the complexity of music and animal song, and their comparisons, are underrepresented. In some ways, music and animal songs are more comparable to each other than to language as propositional semantics cannot be used as indicator of communicative success or wellformedness, and notions of grammaticality are less easily defined. This review brings together accounts of the principles of structure building in music and animal song. It relates them to corresponding models in formal language theory, the extended Chomsky hierarchy (CH), and their probabilistic counterparts. We further discuss common misunderstandings and shortcomings concerning the CH and suggest ways to move beyond. We discuss language, music and animal song in the context of their function and motivation and further integrate problems and issues that are less commonly addressed in the context of language, including continuous event spaces, features of sound and timbre, representation of temporality and interactions of multiple parallel feature streams. We discuss these aspects in the light of recent theoretical, cognitive, neuroscientific and modelling research in the domains of music, language and animal song.

Parallel, multi-stage processing of colors, faces and shapes in macaque inferior temporal cortex

Visual-object processing culminates in inferior temporal (IT) cortex. To assess the organization of IT, we measured fMRI responses in alert monkey to achromatic images (faces, fruit, bodies, places) and colored gratings. IT contained multiple color-biased regions, which were typically ventral to face patches and, remarkably, yoked to them, spaced regularly at four locations predicted by known anatomy. Color and face selectivity increased for more anterior regions, indicative of a broad hierarchical arrangement. Responses to non-face shapes were found across IT, but were stronger outside color-biased regions and face patches, consistent with multiple parallel streams. IT also contained multiple coarse eccentricity maps: face patches overlapped central representations; color-biased regions spanned mid-peripheral representations; and place-biased regions overlapped peripheral representations. These results suggest that IT comprises parallel, multi-stage processing networks subject to one organizing principle.

Fabrication of uniform multi-compartment particles using microfludic electrospray technology for cell co-culture studies

In this work, we demonstrate a robust and reliable approach to fabricate multi-compartment particles for cell co-culture studies. By taking advantage of the laminar flow within our microfluidic nozzle, multiple parallel streams of liquids flow towards the nozzle without significant mixing. Afterwards, the multiple parallel streams merge into a single stream, which is sprayed into air, forming monodisperse droplets under an electric field with a high field strength. The resultant multi-compartment droplets are subsequently cross-linked in a calcium chloride solution to form calcium alginate micro-particles with multiple compartments. Each compartment of the particles can be used for encapsulating different types of cells or biological cell factors. These hydrogel particles with cross-linked alginate chains show similarity in the physical and mechanical environment as the extracellular matrix of biological cells. Thus, the multi-compartment particles provide a promising platform for cell studies and co-culture of different cells. In our study, cells are encapsulated in the multi-compartment particles and the viability of cells is quantified using a fluorescence microscope after the cells are stained for a live/dead assay. The high cell viability after encapsulation indicates the cytocompatibility and feasibility of our technique. Our multi-compartment particles have great potential as a platform for studying cell-cell interactions as well as interactions of cells with extracellular factors.

Multistream Recognition of Speech: Dealing With Unknown Unknowns

The paper discusses an approach for dealing with unexpected acoustic elements in speech. The approach is motivated by observations of human performance on such problems, which indicate the existence of multiple parallel processing streams in the human speech processing cognitive system, combined with the human ability to know when the correct information is being received. Some earlier relevant engineering approaches in multistream automatic recognition of speech (ASR) that aimed at processing of noisy speech and at dealing with unexpected out-of-vocabulary words are reviewed. The paper also reviews some currently active research in multistream ASR, focusing mainly on feedback-based techniques involving fusion of information between individual processing streams. The difference between the system behavior on its training data and during its operation is proposed as a substitute for the human ability of “knowing when knowing.” Most recent results indicate 9% relative improvement in error rates in phoneme recognition of high signal-to-noise ratio speech and as high as 30% relative improvements in moderate noise.

End-to-End Data-Flow Parallelism for Throughput Optimization in High-Speed Networks

The increase in the data produced by large-scale scientific applications necessitates innovative solutions for efficient transfer of data. Although the current optical networking technology reached theoretical speeds of 100 Gbps, applications still suffer from inefficient transport protocols and bottlenecks on the end-systems (e.g. disk, CPU, NIC). High-performance systems provide us with parallel disks, processors and network interfaces. However the lack of orchestration of these end-system resources with the available network capacity results in underutilization of the network bandwidth. In this study, a model and two algorithms that use `end-to-end data-flow parallelism' to optimize the use of network and end-system resources are proposed. This is achieved by using multiple parallel streams over the network; and multiple parallel disks and CPUs at the end systems. Our model predicts the optimal number of streams and disk/CPU stripes that maximizes the data transfer speed for any setting. Our algorithms use GridFTP parallel samplings and calculate the optimal level of parallelism based on our prediction model. The experiments conducted by using actual GridFTP transfers show that the predictions performed by our model and algorithms provide close-to-optimal performances with negligible overhead and use minimal number of resources. The end-to-end data transfer throughput is improved dramatically in existence of end-system bottlenecks compared to the non-optimized transfers.

109 The role of dopamine in memory consolidation: evidence from patients with Parkinson's disease

Effective learning and memory underlie successful human behaviour. Much experimental evidence suggests that multiple parallel memory streams operate over different time scales. As an example, doctors learn and retain knowledge...

Prediction of Optimal Parallelism Level in Wide Area Data Transfers

Wide area data transfer may be a major bottleneck for the end-to-end performance of distributed applications. A practical way of increasing the wide area throughput at the application layer is using multiple parallel streams. Although increased number of parallel streams may yield much better performance than using a single stream, overwhelming the network by opening too many streams may have an inverse effect. The congestion created by excess number of streams may cause a drop down in the throughput achieved. Hence, it is important to decide on the optimal number of streams without congesting the network. Predicting this "optimum” number is not straightforward, since it depends on many parameters specific to each individual transfer. Generic models that try to predict this number either rely too much on historical information or fail to achieve accurate predictions. In this paper, we present a set of new models which aim to approximate the optimal number with least history information and lowest prediction overhead. An algorithm is introduced to select the best combination of historic information to do the prediction for evaluation purposes as well as optimizing prediction by reducing error rate. We measure the feasibility and accuracy of the proposed prediction models by comparing to actual GridFTP data transfer by using little historical information and have seen that we could predict the throughput of parallel streams accurately and find a very close approximation of the optimal stream number.

Exploiting spatial multiplexing and reuse in multi-antenna wireless ad hoc networks

Efficient exploitation of multiple antenna capabilities in ad hoc networks requires carefully designed cross-layer techniques. The work presented in this paper provides a medium access control (MAC)/physical cross-layer scheme for ad hoc networks to address several of the challenges involved in cross-layer design. Multiple antenna systems can be used to increase data rate by spatial multiplexing, that is communicating multiple parallel streams, and to increase spatial reuse by interference suppression. Our proposed scheme, called HYB, exploits both spatial multiplexing and reuse so a receiver node can receive multiple simultaneous data streams from a desired transmitter while suppressing interference from other transmitters in the neighborhood. HYB partitions the available degrees of freedom in the antenna array between spatial multiplexing and reuse which allows the user to obtain different performance characteristics. The applicability of HYB spans across all wireless environments, including line-of-sight and dense multipath scenarios. Simulations demonstrate the significant performance gains and flexibility offered by HYB. The simulation results also offer key insights into the multi-antenna resource allocation problem in ad hoc networks based on traffic patterns and network/transport layer protocols, and consequently provide guidelines for network configuration/management. We show that throughput increases when the degrees of freedom allocated to spatial multiplexing increases, while fairness increases when the degrees of freedom allocated to spatial reuse increases.

Modeling and performance evaluation of transport protocols for firewall control

Firewalls are a crucial building block for securing IP networks. The usage of out-of-band signaling protocols such as SIP for IP telephony and multimedia applications requires a dynamic control of these firewalls and imposes several challenges. Recently, several firewall control architectures and protocols have been developed. The main focus of this paper is the simple middlebox configuration protocol (SIMCO), which is a new transaction-based firewall control protocol. Due to the impact on call setup delays, firewall signaling requires small end-to-end delays and thus mandates a careful choice of the transport protocol. Therefore, this paper studies SCTP, TCP and UDP-based transport for SIMCO and compares different configurations that allow to optimize the performance. We present an analytical model to quantify the impact of head-of-line blocking in SCTP and TCP and verify it with measurements. Both the model and measurements reveal that SCTP can significantly reduce the SIMCO response times by leveraging transmission over multiple parallel streams. While already a few SCTP streams can almost completely avoid head-of-line blocking, our results show that TCP- and UDP-based transport may suffer from significantly larger delays.

Evaluation of Advanced TCP Stacks on Fast Long-Distance Production Networks

With the growing needs of data intensive science, such as high energy physics, and the need to share data between multiple remote computer and data centers worldwide, the necessity for high network performance to replicate large volumes (TBytes) of data between remote sites in Europe, Japan and the U.S. is imperative. Currently, most production bulk-data replication on the network utilizes multiple parallel standard (Reno based) TCP streams. Optimizing the window sizes and number of parallel stream is time consuming, complex, and varies (in some cases hour by hour) depending on network configurations and loads. We therefore evaluated new advanced TCP stacks that do not require multiple parallel streams while giving good performances on high speed long-distance network paths. In this paper, we report measurements made on real production networks with various TCP implementations on paths with different Round Trip Times (RTT) using both optimal and sub-optimal window sizes.We compared the New Reno TCP with the following stacks: HS-TCP, Fast TCP, S-TCP, HSTCP-LP, H-TCP and Bic-TCP. The analysis will compare and report on the stacks in terms of achievable throughput, impact on RTT, intra- and inter-protocol fairness, stability, as well as the impact of reverse traffic.We also report on some tentative results from tests made on unloaded 10 Gbps paths during SuperComputing 2003.