Auxiliary Streams Research Articles

ГИДРОБИОЛОГИЧЕСКИЕ СООБЩЕСТВА СРЕДНЕГО ТЕЧЕНИЯ РЕКИ ЛЕНЫ

The investigated site is located within the area of the Yakutsk Urban District and subjected to a high anthropogenic load. The construction of a bridge over the Lena River at its middle reaches is crucial for transport accessibility but will have a negative impact on aquatic bioresources and their habitat. Previously, this section of the river has not been studied, so the results will be indicative of the current state of aquatic biological resources and their habitat. This factor determined the aim of this study: the status assessment of the hydrobionts inhabiting a localized area in the middle reaches of the Lena River. The hydrochemical analysis of water samples has been carried out in the laboratory of the Republican Center for Information, Analysis and Environmental Monitoring (State Budgetary Institution “RIATSEM”); collection and laboratory processing of zooplankton and zoobenthos samples have been conducted according to generally accepted methods. The hydrochemical composition and dissolved gases of the aquatic environment in the localized section of the Middle Lena River in the vicinity of the bridge crossing are favorable for the development of organic life. Zooplankton is represented by 54 species, more than a half of which is comprised by rotifers (52 %). The average biomass of zooplankton in the spring and summer seasons was 1.135 g/m3; in the autumn and winter seasons it was 0.057 g/m3, and the average annual value was 0.238 g/m3. Crustaceans have the highest share in the biomass, and rotifers are the most abundant. Zoobenthic organisms are represented by 9 groups; oligochaetes and chironomid larvae prevail throughout the year. The average biomass of the zoobenthos in the area along the shore was 37.41 g/m2; in the auxiliary streams it was 174.84 g/m2, and in the main course it was 3.52 g/m2. Following the results of this study, the qualitative and quantitative characteristics of the invertebrates have been found to be indicative of a favorable state of their habitat.

Epidemic tracking and forecasting: Lessons learned from a tumultuous year

Epidemic forecasting has garnered increasing interest in the last decade, nurtured and scaffolded by various forecasting challenges organized by groups within the US federal government, including the Centers for Disease Control and Prevention (CDC) (1⇓–3), Office of Science and Technology Policy (OSTP) (4), and Defense Advanced Research Projects Agency (DARPA) (5), and elsewhere (6, 7). In 2017, after several years of experimentation with flu forecasting in academic groups, the CDC decided to incorporate influenza forecasting into its normal operations, including weekly public communications (8) and briefing to higher-ups. To provide more reliable infrastructure and support for its forecasting needs, the CDC in 2019 designated two national Centers of Excellence for Influenza Forecasting, one at the University of Massachusetts at Amherst (https://reichlab.io/people) and one at Carnegie Mellon University (https://delphi.cmu.edu/about/center-of-excellence/). Not unrelatedly, the last decade has also seen a rise in the importance of digital surveillance streams in public health, with improving epidemic tracking and forecasting models being a key application of these data. Digital streams, such as search and social media trends, have constituted a large part of the focus (9⇓⇓⇓⇓–14); however, even more broadly, data from auxiliary streams that operate outside of traditional public health reporting, such as online surveys, medical devices, or electronic medical records (EMRs), have received considerable attention as well (15⇓⇓⇓⇓⇓⇓⇓⇓⇓–25). The Carnegie Mellon Delphi group, which the two of us colead, has worked in both of these emerging disciplines—epidemic forecasting and building relevant auxiliary signals to aid such forecasting models—since 2012. In 2020, as the pandemic broke out, we struggled like many other groups to find ways to contribute to the national efforts to respond to the pandemic. We ended up shifting our … [↵][1]1To whom correspondence may be addressed. Email: ryantibs{at}cmu.edu. [1]: #xref-corresp-1-1

Validating XML documents in the streaming model with external memory

We study the problem of validating XML documents of size N against general DTDs in the context of streaming algorithms. The starting point of this work is a well-known space lower bound. There are XML documents and DTDs for which p -pass streaming algorithms require Ω( N / p ) space. We show that when allowing access to external memory, there is a deterministic streaming algorithm that solves this problem with memory space O(log 2 N ), a constant number of auxiliary read/write streams, and O(log N ) total number of passes on the XML document and auxiliary streams. An important intermediate step of this algorithm is the computation of the First-Child-Next-Sibling (FCNS) encoding of the initial XML document in a streaming fashion. We study this problem independently, and we also provide memory-efficient streaming algorithms for decoding an XML document given in its FCNS encoding. Furthermore, validating XML documents encoding binary trees against any DTD in the usual streaming model without external memory can be done with sublinear memory. There is a one-pass algorithm using O(√ N log N ) space, and a bidirectional two-pass algorithm using O(log 2 N ) space which perform this task.

Effect of chip-level asynchronism on a CDMA-based overlay system for optical network management

Recently, an all-digital overlay system has been developed in for providing useful management functionalities in optically routed networks. The main feature of the system is to overlay a low-rate stream of management data on a high-rate payload data channel so that the low-rate stream can be recovered by low-cost decoders located at various points within the network. The two key components of the overlay architecture are (i) a constant weight code used for multiplexing payload data streams, and (ii) a CDMA-based protocol used for managing interference among auxiliary data streams. In this work, we provide a general analysis under chip-asynchronous conditions, thereby extending a previous study under chip-synchronous conditions. Our analysis reveals that the bit error rate of the management data channel is limited by the presence of the payload interference. We show that significant performance improvements can be achieved by exploiting the covariance structure of the payload interference and investigate several low-complexity linear detection strategies. Analytical and numerical performance results are provided, and fundamental tradeoffs among several system parameters are identified.

Zerotree-based stereoscopic video CODEC

Due to the provision of a more natural representation of a scene in the form of left and right eye views, a stereoscopic imaging system provides a more effective method for image/video display. Unfortunately the vast amount of information that must be transmitted/stored to represent a stereo image pair/video sequence, has so far hindered its use in commercial applications. However, by properly exploiting the spatial, temporal and binocular redundancy, a stereo image pair or a sequence could be compressed and transmitted through a single monocular channel's bandwidth without unduly sacrificing the perceived stereoscopic image quality. We propose a timely and novel framework to transmit stereoscopic data efficiently. We propose a timely and novel framework to transmit stereoscopic data efficiently. We present a new technique for coding stereo video sequences based on discrete wavelet transform (DWT) technology. The proposed technique particularly exploits zerotree entropy (ZTE) coding that makes use of the wavelet block concept to achieve low bit rate stereo video coding. One of the two image streams, namely, the main stream, is independently coded by a zerotree video CODEC, while the second stream, namely, the auxiliary stream, is predicted based on disparity compensation. A zerotree video CODEC subsequently codes the residual stream. We compare the performance of the proposed CODEC with a discrete cosine transform (DCT)-based, modified MPEG-2 stereo video CODEC. We show that the proposed CODEC outperforms the benchmark CODEC in coding both main and auxiliary streams.

Performance of fractionating reactors in the absence of rate limitations

AbstractA fractionating reactor for equilibrium‐limited reactions is studied theoretically. Reactant A is fed in the center of the countercurrent fractionating system. Product P is effectively transported with the auxiliary phase, while product Q is effectively transported with the main phase, in which the reaction takes place. Model calculations were based on partition and reaction equilibrium at all stages. These show that if the initial reactant concentration and the flow rates are properly selected, the extent of conversion will significantly exceed the corresponding batch conversion. To approach complete conversion in the fractionating reactor, and to recover both products in a pure form, net transport of reactant in either of the countercurrent directions should be prevented. However, irrespective of the number of equilibrium stages, this situation cannot be fully reached when the reactant feed stream is too large (compared with the main and auxiliary streams). Nonetheless, one of the two products may be recovered in a pure form even for such large feed streams. Copyright © 2004 Society of Chemical Industry