Stream Classes Research Articles

Lahar demonstration

Lahar is a warehousing system for Markovian streams ---a common class of uncertain data streams produced via inference on probabilistic models. Example Markovian streams include text inferred from speech, location streams inferred from GPS or RFID readings, and human activity streams inferred from sensor data. Lahar supports OLAP-style queries on Markovian stream archives by leveraging novel approximation and indexing techniques that efficiently manipulate stream probabilities. This demonstration allows users to interactively query a warehouse of imprecise text streams inferred automatically from audio podcasts. Through this interaction, the demo introduces users to the challenges of Markovian stream processing as well as technical contributions developed to address these challenges.

Enhancing prospective teachers’ science teaching efficacy beliefs through scaffolded, student-directed inquiry

This study examined the impact of a recently revised science course that engaged preservice teachers in a scaffolded, student-directed inquiry unit on local streams. Upon the completion of the inquiry project, the teacher candidates in the stream study classes demonstrated significantly greater improvement in the personal science teaching efficacy (PSTE) beliefs than their peers did in the non-stream study classes. Furthermore, the paper reported how the prospective elementary teachers perceived their understandings of science and the instructional strategies related to the stream study unit. Implications and recommendations for future studies are also discussed.

Factors influencing smoking behaviours among male adolescents In Kuantan District

The aims of this study were to determine the prevalence and factors that influenced smoking behaviours among male adolescents in Kuantan, Pahang. A cross-sectional study was conducted among the form four male students in Kuantan District. Three hundred and twenty three students were randomly selected from eight secondary schools. A self-administered questionnaire was distributed to all the respondents. Almost half of the sample was smokers (45.8%) and half of them were Malays (53.1%). Students whose parents had lower level of occupation were more likely to smoke (58.8%). Among smokers, 34.5% of them smoked since primary school and a majority (91.7%) smoked 10 or less cigarettes per day. Half of them (53.4%) reported that they bought loose cigarettes and most of them used their school pocket money to purchase the cigarettes (81.7%). From the multivariate analysis, it was found that Non-Science Stream classes (OR=3.92, 95% CI= 2.10, 7.32), peers' smoking (OR=6.07, 95% CI= 2.32, 15.92), and attitude towards smoking (OR= 21.93, 95% CI= 9.71,49.51) were significantly associated with smoking habit. The prevalence of smoking among male adolescents was considerably high'in this population. It is recommended that antismoking activities in school be carried out regularly and should involve an active participation from the adolescents themselves since peers have great influence on smoking habits.

Development of diatom indicators of ecological conditions for streams of the western US

The species composition of benthic diatoms was related to environmental conditions in streams throughout the western US to develop diatom traits, indicators for assessment of biological condition and indicators for diagnosing stressors. We hypothesized that indicators based on species traits determined for subsets of streams with similar natural landscape features would be more precisely related to environmental conditions than would be indicators calculated based on species traits for all streams in the data set. The ranges of many environmental conditions were wide among western streams, and these conditions covaried greatly along a major environmental gradient characterized by positive correlations among % watershed disturbed by agricultural and urban land uses (% WD), conductivity, total N, total P, and % fine sediments. Species traits were calculated for 242 diatom taxa. Weighted average (WA) methods were used to define species environmental optima, and regression approaches were used to determine whether species were sensitive or tolerant to environmental conditions indicated by % WD, total P, total N, a nutrient multivariate index, pH, conductivity, % fine sediments, % embeddedness, and a watershed disturbance multivariate index. Indicators based on WA optima and sensitive/tolerant traits were highly correlated with these environmental conditions. Natural and anthropogenic conditions varied greatly among classes of streams grouped by climate regions, but indicators developed for the entire western US were consistently more accurate than were regional indicators. Indicators for individual stressors, such as total P, conductivity, and % embeddedness, were highly correlated with values of respective stressors, but covariation among all indicators and stressors indicated that only 1 environmental gradient was reliably reflected by the indicators. Thus, robust indicators of the biological condition of diatom assemblages were developed for streams of the western US, but development of stressor-specific indicators will require application of additional analytical approaches.

Effectiveness of the river environment classification in the Auckland Region

Abstract: The River Environment Classification (REC) provides a GIS‐based tool to differentiate between biophysical attributes of river systems. This study tests the effectiveness of the REC as a tool to differentiate physical habitat and macroinvertebrate assemblages between four classes of stream in the Auckland region. Results indicate significant within‐class variability in physical habitat and macroinvertebrate assemblages, with considerable overlap among the four classes. Biophysically meaningful stream classes cannot be identified from GIS‐derived data applied in this research. Field analyses of physical habitat (i.e. geomorphic river condition) are required as a supplementary tool to interpret ecological relationships for differing stream types.

Distributed musical performances

An increasing number of novel applications produce a rich set of different data types that need to be managed efficiently and coherently. In this article we present our experience with designing and implementing a data management infrastructure for a distributed immersive performance (DIP) application. The DIP project investigates a versatile framework for the capture, recording, and replay of video, audio, and MIDI (Musical Instrument Digital Interface) streams in an interactive environment for collaborative music performance. We are focusing on two classes of data streams that are generated within this environment. The first category consists of high-resolution isochronous media streams, namely audio and video. The second class comprises MIDI data produced by electronic instruments. MIDI event sequences are alphanumeric in nature and fall into the category of the data streams that have been of interest to data management researchers in recent years. We present our data management architecture, which provides a repository for all DIP data. Streams of both categories need to be acquired, transmitted, stored, and replayed in real time. Data items are correlated across different streams with temporal indices. The audio and video streams are managed in our own High-performance Data Recording Architecture (HYDRA), which integrates multistream recording and retrieval in a consistent manner. This paper reports on the practical issues and challenges that we encountered during the design, implementation and experimental phases of our prototype. We also present some analysis results and discuss future extensions for the architecture.

The Role of Observer Variation in Determining Rosgen Stream Types in Northeastern Oregon Mountain Streams1

Abstract: Consistency in determining Rosgen stream types was evaluated in 12 streams within the John Day Basin, northeastern Oregon. The Rosgen classification system is commonly used in the western United States and is based on the measurement of five stream attributes: entrenchment ratio, width‐to‐depth ratio, sinuosity, slope, and substrate size. Streams were classified from measurements made by three monitoring groups, with each group fielding multiple crews that conducted two to three independent surveys of each stream. In only four streams (33%) did measurements from all crews in all monitoring groups yield the same stream type. Most differences found among field crews and monitoring groups could be attributed to differences in estimates of the entrenchment ratio. Differences in entrenchment ratio were likely due to small discrepancies in determination of maximum bankfull depth, leading to potentially large differences in determination of Rosgen’s flood‐prone width and consequent values of entrenchment. The result was considerable measurement variability among crews within a monitoring group, and because entrenchment ratio is the first discriminator in the Rosgen classification, differences in the assessment of this value often resulted in different determination of primary stream types. In contrast, we found that consistently evaluated attributes, such as channel slope, rarely resulted in any differences in classification. We also found that the Rosgen method can yield nonunique solutions (multiple channel types), with no clear guidance for resolving these situations, and we found that some assigned stream types did not match the appearance of the evaluated stream. Based on these observations we caution the use of Rosgen stream classes for communicating conditions of a single stream or as strata when analyzing many streams due to the reliance of the Rosgen approach on bankfull estimates which are inherently uncertain.

Relationship between the coronal holes and high-speed streams of solar wind

The relationship between two classes of coronal holes and high-speed quasi-stationary streams of solar wind at the Earth’s orbit is investigated. “Open” coronal holes, whose area is invariable or increases with the height over the solar surface, are rated in the first class, and “closed” coronal holes with areas decreasing with the height are referred to as second-class holes. The parameters of the coronal holes are determined from IR and EUV images and spectroheliograms. It is shown that most open coronal holes can be associated with high-speed solar-wind streams, while most closed coronal holes exhibit a much lower correlation with such streams.

Sacrificial girls: a case study of the impact of streaming and setting on gender reform

This article reports on research funded by the Australian Research Council to investigate school responses to gender equity. It addresses the efforts of a disadvantaged school to tackle what they perceived to be gender inequalities, but in the process of constructing a top‐set and bottom‐set/stream class they are developing new forms of old inequalities and new forms of inequalities. This research indicates that despite popular assertions that girls' education has become the priority of schools and education systems, girls are being further disadvantaged through attempts to implement market strategies coupled with gender reform agendas grounded in liberal notions of equity and relying on unsophisticated notions of affirmative action. In addition, this study highlights the extent to which a media‐driven debate about boys' education has influenced the constitution of boys as the ‘new disadvantaged’ with the capacity to determine the nature of gender reform agendas and programmes in schools.

Development of a RIVPACS-type predictive model for bioassessment of wadeable streams in Wyoming

RIVPACS models produce a community-level measure of biological condition known as O/E, which is derived from a comparison of the observed (O) biota with those expected (E) to occur in the absence of anthropogenic stress. We used benthic macroinvertebrate and environmental data collected at 925 stream monitoring stations, from 1993 to 2001, to develop, validate, and apply a RIVPACS model to assess the biological condition of wadeable streams in Wyoming. From this dataset, 296 samples were identified as reference, 157 of which were used to calibrate the model, 46 to validate it, and 93 to examine temporal variability in reference site O/E-values. We used cluster analyses to group the model development reference sites into biologically similar classes of streams and multiple discriminant function analysis to determine which environmental variables best discriminated among reference groups. A suite of 14 categorical and continuous environmental variables best discriminated among 15 reference groups and explained a large proportion of the natural variability in biota within the reference dataset. Eleven of the predictor variables were derived from GIS. As expected, mean O/E-values for reference sites used in model development and validation were near unity and statistically similar. Temporal variability in O/E-values for reference sites was low. Test site values ranged from 0 to 1.45 (mean = 0.73). The model was accurate in both space and time and precise enough (S.D. of O/E-values for calibration data = 0.17) to detect modest alteration in biota associated with anthropogenic stressors. Our model was comparable in performance to other RIVPACS models developed in the United States and can produce effective assessments of biological condition over a broad, ecologically diverse region. We also provide convincing evidence that RIVPACS models can be developed primarily with GIS-based predictor variables. This framework not only simplifies the extraction of predictor variable information while potentially reducing expenditures of time and money in the collection of predictor variable information, but opens the door for development and/or application of RIVPACS models in regions where there is a paucity of local-scale, abiotic information.

Developing biological indicators from diverse data: The Potomac Basin-wide Index of Benthic Integrity (B-IBI)

Abstract A Basin-wide Index of Benthic Integrity (B-IBI) was developed to uniformly assess aquatic ecosystem health of non-tidal, wadeable streams in the multi-jurisdictional Potomac River basin (US). Multiple datasets were merged and used to identify stream classes and discriminating biological metrics. The index (aggregated metric scores) accurately identified 95% of impaired sites. A jackknife cross-validation procedure confirmed the accuracy of the B-IBI. B-IBI assessments generally compare favorably to basin states’ assessments derived from the same data. A habitat quality matrix which includes an indicator of anthropogenic alterations and disturbances is recommended. The Potomac B-IBI is more useful than existing state-specific indexes for stream health comparisons across jurisdictional boundaries and basin-wide. The Potomac B-IBI can improve understanding of water quality issues in the basin and enhance the abilities of water quality managers to make well-informed decisions concerning the basin's non-tidal waters.

Coupling GIS and mulitvariate approaches to reference site selection for wadeable stream monitoring

Geographic Information System (GIS) was used to identify potential reference sites for wadeable stream monitoring, and multivariate analyses were applied to test whether invertebrate communities reflected a priori spatial and stream type classifications. We identified potential reference sites in segments with unmodified vegetation cover adjacent to the stream and in >85% of the upstream catchment. We then used various landcover, amenity and environmental impact databases to eliminate sites that had potential anthropogenic influences upstream and that fell into a range of access classes. Each site identified by this process was coded by four dominant stream classes and seven zones, and 119 candidate sites were randomly selected for follow-up assessment. This process yielded 16 sites conforming to reference site criteria using a conditional-probabilistic design, and these were augmented by an additional 14 existing or special interest reference sites. Non-metric multidimensional scaling (NMS) analysis of percent abundance invertebrate data indicated significant differences in community composition among some of the zones and stream classes identified a priori providing qualified support for this framework in reference site selection. NMS analysis of a range standardised condition and diversity metrics derived from the invertebrate data indicated a core set of 26 closely related sites, and four outliers that were considered atypical of reference site conditions and subsequently dropped from the network. Use of GIS linked to stream typology, available spatial databases and aerial photography greatly enhanced the objectivity and efficiency of reference site selection. The multi-metric ordination approach reduced variability among stream types and bias associated with non-random site selection, and provided an effective way to identify representative reference sites.

General Option Exercise Rules, with Applications to Embedded Options and Monopolistic Expansion

This paper provides a general framework for pricing of real options for wide classes of payoff streams that are functions of Levy processes. As applications, we calculate the values of sequences of embedded options, (which we call Russian dolls), and study two models of expansion of a monopoly. In the first model, the monopoly increases capital stock each time the stochastic demand crosses the boundary of the inaction region. Assuming that above a certain level, the stochastic demand factor increases slower than in the standard geometric Levy models, we demonstrate that the investment threshold is lower than in the standard models. Moreover, in the intermediate range between the regimes of the fast and slow growth, the monopoly may find it optimal to simultaneously increase the capital stock and decrease the output price. In a two-factor model of technology adoption, we show that diffusion and jump uncertainty can produce opposite effects.

General Option Exercise Rules, with Applications to Embedded Options and Monopolistic Expansion

This paper provides a general framework for pricing of real options in continuous time for wide classes of payoff streams that are functions of Levy processes. As applications, we calculate the option values of multi-stage investment/disinvestment problems (sequences of embedded options, which we call Russian dolls), and study two models of expansion of a monopoly. In the first model, each time when the stochastic demand reaches the boundary of the inaction region or crosses it, the monopoly increases capital stock but uses the same production technology. We assume that above a certain level, the stochastic demand factor increases slower than in the standard geometric Levy models, and demonstrate that then the investment threshold is lower than in the standard models. Moreover, in the intermediate range between the regimes of the fast and slower growth, the monopoly may find it optimal to simultaneously increase the capital stock and decrease the output price. The second model is driven by two factors: one factor follows a process with upward jumps and describes the dynamics of the frontier technology, the other - demand uncertainty. The impact of these factors on new technology adoption is analyzed. It is shown that depending on the situation and type of uncertainty, the diffusion uncertainty and jump uncertainty can produce opposite effects.

Dynamic bandwidth recycle algorithm for OVSF–CDMA systems

AbstractThis paper presents a dynamic bandwidth recycle algorithm in the downlink of a WCDMA system using orthogonal variable spreading factor codes (OVSF). It consists of a bandwidth recycle algorithm and a bandwidth reservation algorithm. The bandwidth recycle algorithm is used to recycle bandwidth from current serviced connections when the system does not have enough available bandwidth to support a bandwidth request. The bandwidth reservation algorithm is used to reduce transmission delay caused by suddenly increasing bandwidth requests. Four traffic classes, conversational, streaming, interactive, and background classes, defined by universal mobile telecommunication system (UMTS) are considered. Simulation results show that the bandwidth utilization and block rate are improved, the bandwidth guaranteed to conversational and streaming classes are protected, and the delay time of interactive and background classes are kept under an acceptable value even when the traffic load is heavy. Copyright © 2005 John Wiley & Sons, Ltd.

A call admission control for service differentiation and fairness management in WDM grooming networks

We investigate a call admission control (CAC) mechanism for providing fairness control and service differentiation in a WDM network with grooming capabilities. A WDM grooming network can handle different classes of traffic streams which differ in their bandwidth requirements. We assume that for each class, call interarrival and holding times are exponentially distributed. Using a Markov Decision Process approach, an optimal CAC policy is derived for providing fairness in the network. The Policy Iteration algorithm is used to numerically compute the optimal policy. Furthermore, we propose a heuristic decomposition algorithm with lower computational complexity and good performance. Simulation results compare the performance of our proposed policy with those of Complete Sharing and Complete Partitioning policies. Comparisons show that our proposed policy provides the best performance in most cases. Although this approach is motivated by WDM networks, it may be deployed to determine the optimal resource allocation in many problems in wireless and wired telecommunications systems.

Defining perennial, intermittent, and ephemeral channels in Eastern Kentucky: Application to forestry best management practices

Typically, Forestry Best Management Practices (BMPs) that are applied to riparian areas are dependent upon stream flow duration. Definitions vary but most often perennial, intermittent and ephemeral channels are classified and used to determine the specific BMP prescription for a site. The most common technique to determine stream class is to use USGS Quadrangle “blue line” maps where blue lines are considered perennial, dashed blue lines are considered intermittent, and ephemeral channels occur where there is convergent topography but no lines are present. This research and others indicate that the “blue line” method is highly inaccurate at the site scale, especially for lower flow systems. In this study we use the channel geometry method and watershed characteristics to develop multiple regression models to predict flow duration across the range of channels in the Eastern Coalfield Region of Eastern Kentucky, USA. Based on our set of predictive models, we can explain 78–91% of the observed variability in flow duration. Parameters that were most common in the models included the natural log of watershed area, bankfull width, width:depth ratio, stream slope and entrenchment ratio. By utilizing our most encompassing model (all sites for their longest time period), we were able to develop a table of general guidelines that classified >95% of study channels correctly. Given the high predictive capability of our models and the geographic range of sites, we believe that our table of guidelines is robust for the Eastern Coalfield Physiographic Region of Eastern Kentucky.

Characterizing macroinvertebrate assemblage structure in relation to stream size and tributary position

We examined the variability of macroinvertebrate assemblage structure, species identities, and functional feeding group composition in relation to stream size, tributary position, and in-stream factors in a boreal watershed in Finland. Our study included three riffle sites in each of three stream sections in each of three stream size classes. Multi-response permutation procedure, indicator value method, and canonical correspondence analysis revealed clear differences in assemblage structure among the stream size classes, with a gradual increase of species richness as the stream size increased. Significant differences in assemblage structure were also found among the tributary river systems. The functional feeding group composition broadly followed the river continuum concept, i.e., headwaters were dominated by shredders, gatherers, or filterers, whereas scrapers increased in relative abundance with stream size. There was, however, considerable variation in the functional feeding group composition both among and within the headwater stream sections. Our findings refer to a strong influence of stream size on macroinvertebrate assemblages, but also factors prevailing at the scale of individual riffles should be considered in biodiversity conservation of lotic ecosystems.

Quantitative Characterization of Event Streams in Analysis of Hard Real-Time Applications

Many real-time embedded systems process event streams that are composed of a finite number of different event types. Each different event type on the stream would typically impose a different workload to the system, and thus the knowledge of possible correlations and dependencies between the different event types could be exploited to get tighter analytic performance bounds of the complete system. We propose an abstract stream model to characterize such an event stream. The model captures the needed information of all possible traces of a class of event streams. Hence, it can be used to obtain hard bounded worst-case and best-case analysis results of a system. We show how the proposed abstract stream model can be obtained from a concrete stream specification, and how it can be used for performance analysis. The applicability of our approach and its advantages over traditional worst-case performance analysis are shown in a case study of a multimedia application.

Quality of service and performance issues in multiservice networks subject to voice and video traffics

Third generation networks tend to integrate an ever increasing number of services. Thus, standards and protocols such as the UMTS and Wireless Access Protocol (WAP) should allow any mobile user, in addition to telephony, to navigate the Web, have a videoconference call, etc. However, the integration of services raises a certain number of problems. For example, the advent of new services (such as the Internet) has questioned the traditional traffic models used in the telecommunications world. New models have then been proposed to take into account bursty and self-similar traffic. But in third generation networks, even if several studies have been dedicated to the analysis of the performance of radio technologies, few have been done on the analysis of these networks from an application perspective, when various types of traffic are aggregated. In this paper, the focus is on the performance issues arising in UMTS third-generation wireless networks, subject to voice and video traffics. For that purpose, we adapt existing traffic models or propose new ones, which are based on the UMTS forum specifications and real traffic observations. The models obtained are calibrated and validated by comparison with real traces and used to simulate a UMTS network aggregating various types of traffic. This defines a reference model whose performance was evaluated according to certain metrics of quality of service (QoS). The performance achieved by the implementation is average because the throughputs suggested by the UMTS forum are a little restrictive. It is thus necessary in the design process to carefully define the QoS profiles associated with each class or application. For the streaming class, it would be necessary to install adequate buffers to ensure the quality of service, particularly end-to-end delay. Also, the addition of another QoS management layer has shown to improve the performance.