Scroll Bars Research Articles

Can Listeners Hear How Many Singers are Singing? The Effect of Listener’s Experience, Vibrato, Onset, and Formant Frequency on the Perception of Number of Simultaneous Singers

This study investigated whether listener's experience, presence/absence of vibrato, formant frequency difference, or onset delay affect the ability of experienced and inexperienced listeners to segregate complex vocal stimuli. Repeated measures factorial design. Two sets of stimuli were constructed: one with no vibrato and another with vibrato. For each set, each stimulus was synthesized at four pitches: A3, E4, B4, and F5. Stimuli were synthesized using formant patterns appropriate for the vowel |ɑ|. Frequencies for formants one through four were systematically varied from lower to higher in an attempt to simulate the acoustic results of corresponding changes in vocal tract length. Four formant patterns were synthesized (patterns A-D). Three pairs were created at each pitch, pairing the formants AB (mezzo-soprano/mezzo-soprano), CD (soprano/soprano), and AD (mezzo-soprano/soprano). Each of these three pairs was constructed in three separate conditions: simultaneous onset; the first voice in the pair with an onset delay of 100 milliseconds; and the second voice in the pair with an onset delay of 100 milliseconds. Using a scroll bar, listeners rated how difficult it was for them to hear each stimulus pair as two separate voices. The most difficult combinations to segregate were produced with no vibrato and used simultaneous onset. The easiest conditions to segregate were combinations including a "soprano-like" formant pattern (D) in the vibrato condition. Overall, listener's experience did not affect the perceived difficulty of segregation; however, in the presence of vibrato cues, inexperienced listeners did not use delay cues as an aid in segregation in the same manner as did experienced listeners. Once vibrato was removed from the experimental context, inexperienced listeners were able to use delay to aid in segregation in a similar manner to experienced listeners. Presence/absence of vibrato, formant pattern difference, and onset delay interact in a complex manner to affect the perceived difficulty of voice segregation.

Experimental meandering river with chute cutoffs

Braided rivers are relatively simple to produce in the laboratory, whereas dynamic meandering rivers have not been sustained beyond initial bend formation. Meandering is theoretically explained by bend instability growing from planimetric perturbation, which convects downstream. In this study, we experimentally tested the importance of upstream perturbation and chute cutoff development in the evolution and dynamics of a meandering channel pattern. The initial straight channel had a transversely moving upstream inlet point and silt‐sized silica flour was added to the sediment feed to allow floodplain formation. We obtained a dynamic meandering river with scroll bars. Bend growth was alternated by chute cutoffs that formed across the point bars. Meandering was maintained as one channel was disconnected by a plug bar. The curvature at the chute bifurcation transported sediment and build a new floodplain, while the other channel widens. At the end of the experiment, the fluvial plain exhibited a meandering channel, point bars, chutes and abandoned and partially filled channels with a slightly cohesive floodplain surface similar to natural meandering gravel bed rivers. We conclude that the necessary and sufficient conditions for dynamic meandering gravel bed river are a sustained dynamic upstream perturbation and floodplain formation.

Diseño de hojas de cálculo como herramientas para el aprendizaje del equilibrio ácido-base: uso de la barra de desplazamiento

This article presents a simple and conceptual application of the spreadsheet and the scroll bar to find the composition of a system in chemical equilibrium, for various situations related to monoprotic acid equilibrium. This method allows to simulate different situations such as a) weak acid dilution, b) common ion effect, c) buffer solutions, and d) the composition of a very dilute acid or an acid of very low acid-dissociation constant.

The anastomosing pattern and the extensively distributed scroll bars in the middle Amazon River

ABSTRACTThe middle Amazon River, between the confluences of the Negro and Madeira Rivers in Brazil, shows an anastomosing morphology with relatively stable, multiple interconnected channels that locally enclose floodbasins. Additionally, this system is characterized by sinuous secondary channels with meander development, discontinuous natural levees concentrated on the concave banks and extensively distributed scroll bars mainly in the islands, related to subrecent and present‐day migration of mainly secondary channels. This distinguishes the Amazon from many other anastomosing rivers that have laterally stable, non‐meandering channels. We analyzed sedimentary processes using field data, morphology and channel changes trough a temporal analysis using remote sensing data and obtained optically stimulated luminescence (OSL) dating to understand the genesis of this large anastomosing river and the development of its meandering secondary channels. Scroll bars have developed in a multichannel river system at least since 7.5 ± 0.85 ka. Avulsion is inferred to have played a minor role in the formation of this anastomosing system, with only one documented case while mid‐channel bar formation and chute cut‐offs of the main and secondary channels are the main formative mechanisms of anastomosis in this system. Differences in resistance to erosion control the relatively straight main channel and allow secondary channels to develop a meandering platform. Vegetation contributes to the relative stability of islands and the floodplain. Low gradient and high average aggradation rate (1.1 mm yr−1) are conditions which favor the development of anastomosis. Additionally, stable external conditions, low abandonment rate of older channels and independence from high avulsion frequency suggest a long‐lived, semi‐static type of anastomosing river in this reach of the Amazon. Copyright © 2012 John Wiley & Sons, Ltd.

An overfilled lacustrine system and progradational delta in Jezero crater, Mars: Implications for Noachian climate

The presence of valley networks and open-basin lakes in the late Noachian is cited as evidence for overland flow of liquid water and thus a climate on early Mars that might have supported precipitation and runoff. Outstanding questions center on the nature of such a climate, its duration and variability, and its cause. Open basin lakes, their interior morphology, and their associated channels provide evidence to address these questions. We synthesize the extensive knowledge of terrestrial open basin lakes, deltaic environments, and fluvial systems to assess these questions with evidence from Jezero crater, a 45km diameter open basin lake and its 15,000km2 catchment area, ∼645-km long drainage network, interior sedimentary facies, and ∼50km long outlet channel system. We document the presence of extensive scroll bars and epsilon cross-bedding, both indicative of meandering distributary channels that are not observed on alluvial fans but are typical of fluvial-deltaic depositional environments. A fluvial-deltaic environment is further supported by the post-formational erosion of the deltaic complex: the present-day “delta front” is actually an erosional escarpment truncating delta plain features with the clay-rich prodelta environment, predicted from facies models to make up the outer third of the complex, having been largely removed by eolian erosion. The extensive development via lateral accretion of scroll bars and epsilon cross-bedding, and the reconstructed sedimentary architecture suggest a stable baselevel, in contrast to an environment of constantly rising and falling baselevel related to variable input and evaporation that would favor incision during lowstands. The development of the outlet channel is interpreted to have provided baselevel control in the Jezero open-basin lake. The maturity of the outlet channel, in contrast to the catastrophically scoured landscapes typical of dam-breach channels, favors a consistent overfilled hydrology for the paleolacustrine environment. Sediment transport modeling studies of other valley network and related deposits on Mars have suggested durations in the decades to centuries range. We review meander migration rates in terrestrial fluvial environments to provide a comparison for considering the temporal stability implied by the evolution of scroll bars; values of 20–40 years are not uncommon for the structures and migration implied by observations in Jezero. Taking sediment accumulation rates from a variety of terrestrial fluvial-lacustrine environments in conjunction with our estimates of the sedimentary basin-fill thickness suggest timescales of the order of 106–107 years, far longer than implied by some sediment transport models, but still a short period of time geologically. The presence of significant residual accommodation space (space available for potential sediment accumulation) in Jezero indicates that sediment transport into the lake terminated before the basin was completely filled. Climate conditions sufficient for sustained overland flow of water in the valley networks are required to fill Jezero crater, to cause its breaching in a non-catastrophic manner, and to form the significant fluvial-deltaic environment of laterally migrating fluvial channels and scroll bars formed with an apparently stable baselevel. The lack of late-stage channel downcutting suggests that the conditions producing overland flow of water into the basin may have ended abruptly. Our estimates of the duration of fluvial activity (of order 106–107 years) suggest longer times than previously suggested (years to centuries) by sediment transport models, but generally relatively short durations from a geologic perspective.

COMPUTER PROGRAM TO PREDICT PERFORMANCE OF FAST RUNNING HORIZONTAL AXIS WIND TURBINE TO REACHING THE OPTIMUM DESIGN

A computer program in visual basic was designed to predict the performance of fast running horizontal axis wind turbine for electricity generation by using blade element theory and momentum theory. NACA 4415 was chosen for the aerofoil section of blade. the design parameters ( design tip speed ratio , rotor radius and blade number ) represented in scroll bars was designed in visual basic, and by changing these parameters , solidity, chord line and twist angle curves along the blade, in addition to the rotor performance curve (relation of power coefficient with tip speed ratio), will be draw instantly.
 The numerical integration (trapezoidal method) was used to compute the area under rotor performance curve, the program will record the value of this area, and by change parameter design and by knowing the maximum value of area, we will know the optimal design for turbine rotor.
 The three and four rotor blades and the values of design tip speed ratio between (5 - 9) give the best performance of rotor. The effect change of rotor radius on performance rotor was found very small, and there is no noticed effect to rated wind speed on rotor performance when changing parameter design in computer program

Simulating the heterogeneity in braided channel belt deposits: 2. Examples of results and comparison to natural deposits

In part 1 of this paper (Ramanathan et al., 2010b) we presented a methodology and a code for modeling the hierarchical sedimentary architecture in braided channel belt deposits. Here in part 2, the code was used to create a digital model of this architecture and the corresponding spatial distribution of permeability. The simulated architecture was compared to the real stratal architecture observed in an abandoned channel belt. The comparisons included assessments of similarity which were both qualitative and quantitative. The qualitative comparisons show that the geometries of unit types within the synthetic deposits are generally consistent with field observations. The unit types in the synthetic deposits would generally be recognized as representing their counterparts in nature, including cross stratasets, lobate and scroll bar deposits, and channel fills. Furthermore, the synthetic deposits have a hierarchical spatial relationship among these units consistent with observations from field exposures and geophysical images. In quantitative comparisons the proportions and the length, width, and height of unit types at different scales, across all levels of the stratal hierarchy, compare well between the synthetic and the natural deposits. A number of important attributes of the synthetic channel belt deposits are shown to be influenced by more than one level within the hierarchy of stratal architecture. First, the high‐permeability open‐framework gravels connected across all levels and thus formed preferential flow pathways; open‐framework gravels are known to form preferential flow pathways in natural channel belt deposits. The nature of a connected cluster changed across different levels of the stratal hierarchy, and as a result of the geologic structure, the connectivity occurs at proportions of open‐framework gravels below the theoretical percolation threshold for random infinite media. Second, when the channel belt model was populated with permeability distributions by lowest‐level unit type, the composite permeability semivariogram contained structures that were identifiable at more than one scale, and each of these structures could be directly linked to unit types of different scales existing at different levels within the hierarchy of strata. These collective results are encouraging with respect to our goal that this model be relevant for testing ideas in future research on flow and transport in aquifers and reservoirs with multiscale heterogeneity.

Tidal channel meander formation by depositional rather than erosional processes: examples from the prograding Skagit River Delta (Washington, USA)

AbstractChannel meander dynamics in fluvial systems and many tidal systems result from erosion of concave banks coupled with sediment deposition on convex bars. However, geographic information system (GIS) analysis of historical aerial photographs of the Skagit Delta marshes provides examples of an alternative meander forming process in a rapidly prograding river delta: deposition‐dominated tidal channel meander formation through a developmental sequence beginning with sandbar formation at the confluence of a blind tidal channel and delta distributary, proceeding to sandbar colonization and stabilization by marsh vegetation to form a marsh island opposite the blind tidal channel outlet, followed by narrowing of the gap between the island and mainland marsh, closure of one half of the gap to join the marsh island to the mainland, and formation of an approximately right‐angle blind tidal channel meander bend in the remaining half of the gap. Topographic signatures analogous to fluvial meander scroll bars accompany these planform changes. Parallel sequences of marsh ridges and swales indicate locations of historical distributary shoreline levees adjacent to filled former island/mainland gaps. Additionally, the location of marsh islands within delta distributaries is not random; islands are disproportionately associated with blind tidal channel/distributary confluences. Furthermore, blind tidal channel outlet width is positively correlated with the size of the marsh island that forms at the outlet, and the time until island fusion with mainland marsh. These observations suggest confluence hydrodynamics favor sandbar/marsh island development. The transition from confluence sandbar to tidal channel meander can take as little as 10 years, but more typically occurs over several decades. This depositional blind tidal channel meander formation process is part of a larger scale systemic depositional process of delta progradation that includes distributary elongation, gradient reduction, flow‐switching, shoaling, and narrowing. Copyright © 2010 John Wiley & Sons, Ltd.

Collective indexing of emotions in images. A study in emotional information retrieval

AbstractSome documents provoke emotions in people viewing them. Will it be possible to describe emotions consistently and use this information in retrieval systems? We tested collective (statistically aggregated) emotion indexing using images as examples. Considering psychological results, basic emotions are anger, disgust, fear, happiness, and sadness. This study follows an approach developed by Lee and Neal (2007) for music emotion retrieval and applies scroll bars for tagging basic emotions and their intensities. A sample comprising 763 persons tagged emotions caused by images (retrieved from www.Flickr.com) applying scroll bars and (linguistic) tags. Using SPSS, we performed descriptive statistics and correlation analysis. For more than half of the images, the test persons have clear emotion favorites. There are prototypical images for given emotions. The document‐specific consistency of tagging using a scroll bar is, for some images, very high. Most of the (most commonly used) linguistic tags are on the basic level (in the sense of Rosch's basic level theory). The distributions of the linguistic tags in our examples follow an inverse power‐law. Hence, it seems possible to apply collective image emotion tagging to image information systems and to present a new search option for basic emotions. This article is one of the first steps in the research area of emotional information retrieval (EmIR).

Application Framework with Demand-Driven Mashup for Selective Browsing

This paper proposes a mashup framework for creating flexible mashup applications in which the user can selectively browse through mashup items. Our framework provides a data management engine for on-demand data generation, and GUI components called widgets that can be used to browse through mashed-up data selectively. The application developer has to only prepare a mashup relation specifying the web service combinations and widget configurations specifying how to display the mashed-up data. On the basis of these configurations, widgets monitor user interactions and requests data from the data management engine that processes the demand-driven creation of mashed-up data. To enable selective browsing, a table widget, for instance, allows selection of columns to be displayed, provides a limited view with scroll bars, and filtering facilities. Our framework also offers a mechanism for widget coordination where a widget can change the display target according to states or events of other widgets. We introduce a sample application for tour planning using five cooperative widgets, and discuss the usability and performance advantages of our framework.

Enhancing digital images using unsharp-mask

Sir, I read with interest the article ‘Enhancing digital images using unsharp-mask’ by Taneja.[1] The author has discussed a really interesting aspect of dermatological photography. The use of a sharpening tool is definitely helpful in enhancing communication via images, especially in the context of seeing images on the monitor screens, like in teledermatology, but whether and to what extent the same can be used for manipulation of images for publication purposes raises some ethical concerns. We agree with the author that the ‘unsharp-mask’ tool available in Adobe Photoshop® (the latest being Adobe Photoshop CS4) is probably the gold standard as far as image sharpening is concerned. The same feature is available with other imaging software like Picture Window. There is also a specific software for image sharpening called ‘Sharpener Pro 3.0’. However, this software is not free, and also learning to use the ‘unsharp-mask’ tool might be a bit difficult for people not familiar with Photoshop. For people new to the concept of image sharpening, a simpler tool is available in Picassa 3.0 (which can be downloaded free), where you can simply go to the ‘effects’ tool bar and sharpen the image. The extent of sharpening can be controlled by the horizontal scroll bar.

Linking organic matter deposition and iron mineral transformations to groundwater arsenic levels in the Mekong delta, Cambodia

Enriched As in drinking water wells in south and Southeast Asia has increased the risk of cancer for nearly 100 million people. This enrichment is generally attributed to the reductive dissolution of Fe oxides; however, the complex expression of As enrichment in these areas is not yet well understood. Here, the coupled sedimentological and geochemical factors that contribute to the extent and spatial distribution of groundwater As concentrations in the Mekong River delta, Cambodia in an avulsed scroll bar sequence are examined. X-Ray absorption spectroscopy (XAS) was used to determine Fe and As speciation in redox preserved sediment collected from drilled cores. Dissolved As, Fe and S solution concentrations in existing and newly drilled wells (cores) differed considerably depending on their source sedimentology. The rapid burial of organic matter in the scroll bar sequence facilitated the development of extensive Fe-reducing conditions, and As release into the aquifer. In older features organic C levels are high enough to sustain extensive Fe reduction and provide ample SO4 which is reduced to sulfide. This S reduction impacts As levels; As is sequestered in sulfide minerals outside of the scrollbar sequence, decreasing pore water concentrations. In contrast, As is depleted in sediments from the scroll sequence, and associated with elevated pore water aqueous concentrations. The concentration and form of organic C in the scrollbar sequence is related to depositional environment, and can facilitate Fe and S mineral transformations, distinct sedimentary environments explain a portion of the inherent heterogeneity of aquifer As concentrations.

EGames: Is imagination the forgotten ingredient?

Commercial eGames strive to create seamless transitions between realistic virtual worlds. This condenses the experience and can create more intense engagement. However, there is no evidence that this is essential in eGames used for educational applications. Educators seek nearly opposite attributes. They need materials that can be disaggregated into units small enough to fit within timetables and that can be edited and customised to fit curricula without resort to programming. This paper proposes the alternative of a meta-game – a loose string of game and puzzle tasks in the tradition of heroes’ journeys, tournaments, scavenger hunts, and road rallies. Imagination and symbolism provide the links between otherwise unrelated clues, puzzles, and tasks. Spreadsheets serve as the ideal hub for meta-games. Current spreadsheets include form controls such as scroll bars and buttons, share the same multimedia applications as other office software, and can even create animation. The spreadsheet has the versatility to fill the niche of the cardboard box as a plaything. Research is reviewed that supports a role for eGames with less overt reward and more left to the imagination.

Performance Characteristics of the Suspected Blood Indicator Feature in Capsule Endoscopy According to Indication for Study

The suspected blood indicator (SBI) feature of wireless capsule endoscopy (WCE) was developed for rapid screening of intestinal lesions with bleeding potential. Our aim was to assess the accuracy and performance characteristics of the SBI according to the indications for study in a large cohort of patients. We reviewed collected data on all WCE studies performed at Johns Hopkins Hospital from January 2006 to June 2007. Study indications were as follows: anemia of unknown origin (n = 53), obscure gastrointestinal bleeding (n = 112), suspected Crohn's disease (n = 122), and other (n = 4). Concordant and discordant findings between gastroenterologists' readings and SBI were recorded for each patient. A total of 221 lesions with bleeding potential was detected. The overall sensitivity, specificity, positive predictive value, and negative predictive value for the SBI were 56.4%, 33.5%, 24.0%, and 67.3%, respectively. For actively bleeding lesions, the SBI sensitivity and positive predictive value were only 58.3% and 70%, respectively. The sensitivity was highest (64%) in patients undergoing WCE for suspected Crohn's disease, with a negative predictive value of 80.4%. The sensitivity was only 58.3% and 41.3%, respectively, in studies performed for obscure gastrointestinal bleeding and anemia. Performance characteristics of the currently available SBI feature in WCE are suboptimal and insufficient to screen for lesions with bleeding potential. Even in patients with active intestinal bleeding, the sensitivity of SBI was less than 60%, which is lower than previously reported. However, in patients with suspected Crohn's disease, the high sensitivity and negative predictive value of SBI may make it a useful tool for the detection of large areas of abnormal mucosa.

Geomorphic controls on groundwater arsenic distribution in the Mekong River Delta, Cambodia

Natural arsenic contamination of groundwater is a severe public health crisis affecting nearly 60 million people in South Asia and Southeast Asia alone. Contamination is spatially heterogeneous and results from the coupled microbial decomposition of organic matter and reductive dissolution of arsenic-bearing iron minerals. Here we demonstrate that elevated arsenic concentrations arise in regions of recent organic matter deposition and thus are controlled by fluvial geomorphic processes. Arsenic contamination is best expressed within recent geomorphic features such as docked islands, scroll bars, and avulsions. Within these features, the deposition of rapidly buried reactive organic matter facilitates microbial iron reduction and arsenic release. Ultimately, the organic matter supply is exhausted and the conditions necessary for soluble arsenic to persist diminish.

법학도서관 웹사이트 내비게이션 비교.분석

본 연구에서는 국내 11개 국외 5개의 법학도서관 웹사이트 내비게이션 시스템을 전역, 지역, 문맥, 지원 내비게이션으로 나누어 분석하였다. 그 결과 전역 내비게이션은 일관된 내비게이션을 제공해야 하며, 핵심지역과 기능에 바로 접근할 수 있어야 하는 것으로 나타났다. 지역 내비게이션의 Quick Link는 스크롤바의 이동이 가능하도록 제공할 필요가 있었다. 문맥 내비게이션의 메뉴의 수와 링크 유형은 가급적 적은 수를 제공해야 하는 것으로 나타났다. 마지막으로 지원 내비게이션의 사이트맵과 사이트색인은 웹사이트의 콘텐트의 양에 따라 알맞게 제공해야 하며, 누락된 링크가 없어야 하며 제공내용이 충실해야 하는 것으로 나타났다. In this study, we analyzed the web site navigation of law school libraries in terms of global, local, context, support navigation. The recommendations for good web site design were as follows. First, global navigation should provide the consistent navigation and be able to access to the important site and function. Second, quick links of local navigation need to provide the movement of scroll bar. The number of menu and type of link in context navigation should provide the least number. Finally, the site map and index should provide with qualified contents and minimal errors.

A device for easily browsing various content using the metaphor of reading poetry

We propose an interface for easily accessing a variety of content using the metaphor of reading poetry. The interface is designed to search content by turning the pages of a book-like device. Using the device, the user can easily access desired content without pressing buttons many times, using complex graphical user interfaces, or using a scroll bar to scroll excessively. The prototype we developed can control TV, radio, and media files stored in an HDD and browse the Internet. The interface can be applied as a controller for products such as PCs, TVs, and mobile devices.

An Exploratory Study of How Developers Seek, Relate, and Collect Relevant Information during Software Maintenance Tasks

Much of software developers' time is spent understanding unfamiliar code. To better understand how developers gain this understanding and how software development environments might be involved, a study was performed in which developers were given an unfamiliar program and asked to work on two debugging tasks and three enhancement tasks for 70 minutes. The study found that developers interleaved three activities. They began by searching for relevant code both manually and using search tools; however, they based their searches on limited and misrepresentative cues in the code, environment, and executing program, often leading to failed searches. When developers found relevant code, they followed its incoming and outgoing dependencies, often returning to it and navigating its other dependencies; while doing so, however, Eclipse's navigational tools caused significant overhead. Developers collected code and other information that they believed would be necessary to edit, duplicate, or otherwise refer to later by encoding it in the interactive state of Eclipse's package explorer, file tabs, and scroll bars. However, developers lost track of relevant code as these interfaces were used for other tasks, and developers were forced to find it again. These issues caused developers to spend, on average, 35 percent of their time performing the mechanics of navigation within and between source files. These observations suggest a new model of program understanding grounded in theories of information foraging and suggest ideas for tools that help developers seek, relate, and collect information in a more effective and explicit manner.

A comparison of mud- and sand-dominated meanders in a downstream coarsening reach of the mixed bedrock-alluvial Klip River, eastern Free State, South Africa

Along a 28 km reach of the Klip River, eastern Free State, South Africa, mud- and sand-dominated meanders have developed in close proximity within a floodplain wetland up to 1.5 km wide, providing an unusual opportunity to compare their characteristics under similar hydrological conditions. Throughout the reach, the channel bed is grounded on sandstone/shale bedrock although the banks are alluvial, and most river activity occurs during summer high flows. The reach can be divided into three geomorphological zones: Zone 1 (0–11 km), a muddy proximal part with a single meandering channel (w/d < 10) and near-permanent standing water in oxbows and backswamps; Zone 2 (11–17.5 km), a transitional mud-to-sand part with one main channel (w/d ∼ 20–30), a number of sinuous palaeochannels and oxbows, and only limited standing water; and Zone 3 (17.5–28 km), a sandy distal part with a single meandering channel (w/d ∼ 15–30), scroll bars and oxbows, and little standing water. Each zone also has a distinctive sedimentology: Zone 1 is characterised by an ∼ 3–4 m thick succession of basal sand and minor granules overlain by dominantly muddy sediment deposited primarily by oblique accretion in meander bends; Zone 2 is characterised by < 4 m of interbedded sand and mud deposited primarily by lateral point-bar accretion, although a history of avulsions also attests to the importance of abandoned-channel accretion; and Zone 3 is characterised by < 3 m of dominantly sand deposited primarily by lateral point-bar accretion. This unusual downstream sediment coarsening trend, and the associated changes in channel and floodplain character, are independent of sediment inputs from tributaries, and result from a downstream increase in bankfull unit stream power from < 3.5 W m − 2 (Zone 1) to ∼ 4–10 W m − 2 (Zone 3). Mud is deposited primarily in low-energy Zone 1 but is conveyed in suspension more effectively through higher energy Zones 2 and 3, only forming drapes over sandy lateral accretion deposits during waning flood stages. The downstream increase in unit stream power is controlled in part by a slight downstream increase in floodplain gradient that may be related to a subtle variation in the erosional resistance of the bedrock underlying the channel bed. These findings add to previous work on meandering rivers by demonstrating that mud-dominated meanders can occur in long-term erosional settings where the channel bed is grounded on bedrock, and that downstream fining trends may be reversed locally.

Stratigraphy and lithologic heterogeneity in the Mannville Group (southeast Saskatchewan) defined by integrating 3-D seismic and log data

Abstract Wireline log and 3-D seismic data were integrated to define stratigraphic units and lithologic heterogeneity in the Mannville Group of southeast Saskatchewan. The Mannville in this area is a stratigraphically complex unit formed of fluvial to marine deposits that, although non-prospective for hydrocarbons in this area, share many similarities with time-equivalent strata in areas of heavy oil production. Seismic sequence stratigraphic principles permitted us to subdivide the Mannville into three packages. The ability to visualize the 3-D seismic data in a variety of ways, including arbitrary lines and stratal or horizon slicing techniques, helped us to define stratigraphic features that would affect fluid flow in hydrocarbon producing areas. These features include channels of various sizes and orientations, and channel elements such as scroll bars and lateral accretion surfaces, that are present within specific portions of the Group. Because the effectiveness of enhanced recovery methods such as steam-assisted gravity drainage depends on a development team's ability to recognize reservoir heterogeneity, similar integration of 3-D seismic, well logs and other data types would assist greatly in developing the Mannville in heavy oil areas. There is close, but not one-to-one, correspondence between the stratigraphic units we defined and those established by regional log- and core-based correlations. Seismic resolution problems or log correlation styles could be responsible for the differences.