Tripod Data Research Articles

Exploring academic teasing: predictors and outcomes of teasing for making mistakes in classrooms

ABSTRACT People in ideal learning environments recognize the value of making mistakes and welcome them. However, the reality in many classrooms is that students are ridiculed by their peers for making mistakes. This paper explores academic teasing in schools, i.e. making fun of others for making mistakes. Using Tripod student survey data from spring 2017, this paper demonstrates the prevalence of academic teasing in a large, diverse and urban district in the Southern United States. Additionally, using Tripod data from 2012–15, this study tests potential predictors and outcomes of academic teasing. Analyses apply hierarchical linear modeling (HLM). Results indicate that some students of color are significantly more exposed to academic teasing than White students, and that academic teasing is a significant predictor of students’ hiding and holding back academic effort. Furthermore, teachers with better teaching skills have less academic teasing in their classrooms, controlling for student body composition. Implications are discussed.

Evaluation of in situ and remote sensing sampling methods for SPM concentrations, Belgian continental shelf (southern North Sea)

Large sets of suspended particulate matter (SPM) concentration data from in situ and remote sensing (moderate resolution imaging spectroradiometer, MODIS) samplings in the Belgian nearshore area (southern North Sea) are combined in order to evaluate their heterogeneity and the sampling techniques. In situ SPM concentration measurements are from a vessel (tidal cycle) and from a tripod. During the tidal cycle measurements, vertical profiles of SPM concentration have been collected; these profiles have been used as a link between satellite surface and near-bed tripod SPM concentrations. In situ time series at fixed locations using a tripod are excellent witnesses of SPM concentrations under all weather conditions and may catch SPM concentration variability with a much finer scale. The heterogeneity has been statistically assessed by comparing the SPM concentration frequency distributions. Tidal cycle, tripod and MODIS datasets have different distributions and represent a different subpopulation of the whole SPM concentrations population. The differences between the datasets are related to meteorological conditions during the measurements; to near-bed SPM concentration dynamics, which are partially uncoupled from processes higher up in the water column; to the sampling methods or schemes and to measurement uncertainties. In order to explain the differences between the datasets, the tripod data have been subsampled using wave height conditions and satellite and tidal cycle sampling schemes. It was found that satellites and low-frequent tidal cycle measurements are biased towards good weather condition or spring–summer seasons (satellite). The data show that the mean surface SPM concentration derived from satellite data is slightly lower than from in situ tidal cycle measurements, whereas it is significantly lower than the mean SPM concentration interpolated to the water surface from the tripod measurements. This is explained by the errors arising from the interpolation along the vertical profiles, but also by the fact that satellite-measured signal saturates in the visible band used to retrieve SPM concentration in very turbid waters.

Deposition by seasonal wave- and current-supported sediment gravity flows interacting with spatially varying bathymetry: Waiapu shelf, New Zealand

The Waiapu River sedimentary system, New Zealand, provides a prototype for investigating the relative importance of wave- versus current-supported gravity flows on continental shelf deposition. A two-dimensional model was used to represent gravity-driven sediment transport and deposition on the Waiapu shelf over an annual cycle of storm events and associated Waiapu River floods. Model inputs of waves and wind-driven currents were derived from WAVEWATCH III hindcasts and constrained by benthic tripod data. The 12-month model run included a low-energy period (September 2003 to May 2004) with weak waves and currents and low river discharge, and a high-energy period (May to August 2004) with stronger waves and wind-driven currents and more frequent river floods. Model results suggested that during the low-energy period, riverine sediment was trapped between the 20- and 80-m isobaths. During the high-energy period, sediment was deposited obliquely across the shelf between the 60- and 120-m isobaths. The predicted deposit locations for the low- and high-energy periods, respectively, were consistent with short- and long-term observed accumulation patterns based on 7Be and 210Pb activity [Kniskern, T.A., Kuehl, S.A., Harris, C.K., Carter, L., 2010. Sediment accumulation patterns and fine-scale strata formation on the Waiapu River shelf, New Zealand. Marine Geology 270, 188–201]. Gravity flows were mainly wave-supported landward of the 60-m isobath, but became increasingly current-supported as wave orbital velocity attenuated in deeper water. Both analytical theory and numerical results indicated that wave-supported gravity currents were sensitive to local water depth and favored deposition parallel to isobaths as depth increased. In contrast, current-supported gravity currents were more sensitive to spatial variations in seabed slope, with seaward decreases in slope and along-shelf embayment of bathymetry favoring transport convergence and deposition. We conclude that the longer term (∼ 100 yr) shelf-oblique mud deposit on the Waiapu shelf mainly reflects current-supported gravity flows responding to local variations in seabed slope and curvature of isobaths.

Bottom instrumented tripods: History, applications, and impacts

Instrumented bottom tripods have provided important data on sediment transport processes on continental shelves and in estuaries for four decades. Since the initial deployment in a tidal channel in Puget Sound, WA, in 1965 numerous tripods have been constructed to investigate bottom boundary layer and sediment dynamics worldwide. Tripod data have led to new understanding of near-bottom wave and current flows in the coastal ocean, and have been crucial to the development of shelf circulation and sediment transport models. Calculations of bottom stress, bottom roughness, and sediment flux that resulted directly from tripod data have been compared to bottom boundary layer model results. Where these have differed, new or revised model components have been developed to improve the skill of the models. The many discoveries that have been made from tripod experiments include dense, near-bottom fluid mud layers that transport large quantities of suspended sediment offshore into deeper regions of the continental shelf. This process has been linked to the seaward progradation of subaqueous deltas and to the boundaries of mid-shelf mud deposits off rivers with high fine-sediment discharge.

Clinoform mechanics in the Gulf of Papua, New Guinea

The largest islands of the Indo-Pacific Archipelago are estimated to account for 20–25% of the global sediment discharge to the ocean, and much (>50%) of this sediment is supplied to wide (>150km) continental shelves. These conditions are conducive to creation of large-scale morphologic features known as clinoforms—sigmoidal-shaped deposits on the continental shelf. The Gulf of Papua (GOP) receives 3.84 ×108tons of sediment annually from three principal sediment suppliers, the Fly, Kikori and Purari Rivers, and its prograding clinoform is the focus of this study. During three research cruises, 80 cores and 37 CTD/optical backscatter casts were collected, and an instrumented tripod was deployed twice. Sedimentological and radiochemical results indicate that the GOP clinoform has characteristics similar to those seaward of other major rivers (e.g., Amazon, Ganges–Brahmaputra), specifically sand/mud interbedding on the topset, rapidly accumulating muds on the foreset, and siliciclastic mud mixed with carbonate sand on the bottomset.Using core data and field observations, the mechanics of clinoform progradation are examined. Discrete, large sedimentation events are identified as processes building the clinoform feature. X-radiographs from foreset cores reveal thick beds (>5cm) between bioturbated sections. Detailed 210Pb and grain-size data indicate that low activities and increased clay contents are associated with these beds. They are hypothesized to be formed by fluid–mud deposition in response to periods of large wave-tide bed shear stresses, more likely during the SE-tradewind season, and their regular occurrence produces high rates of mean accumulation (∼4cm/y). Bed preservation is determined by the rates of sediment accumulation and bioturbation.To assess the influence of physical oceanographic factors on clinoform shape, bottom shear stresses from tides and surface waves were calculated using available wave and tripod data. This effort reveals that the depth range (25–40m) of the clinoform rollover point (seaward edge of the topset region) is roughly consistent with the sediment-transport regime. Furthermore, calculations corroborate the core data that suggest possible seasonal sediment storage in the inner topset region (<15-m water depth, during the NW-monsoon winds) with subsequent transfer to foreset beds (more probable during SE-tradewind conditions).A 100-yr sediment budget created with accumulation rate data suggests approximately 20% of the total sediment supplied to the GOP accumulates on the clinoform (creating the clinoform morphology). Less than 5% is believed to escape to the adjacent slope, and much of the remaining 75% is likely trapped on the inner-topset region (<20m water depth) and within the mangrove forests and flood/delta plains of the northern GOP.

Sediment-transport events on the northern California continental shelf

A long-term monitoring tripod has been maintained in 60-m water depth at the northern end of the STRATAFORM study site on the northern California continental shelf. As part of this ongoing study, tripod data for 1 year beginning 24 September 1995 are used to provide a sediment-transport analysis on an event-by-event basis. The objective of this paper is to highlight the energetic nature of this shelf region in terms of the frequency, duration, and magnitude of sediment-suspension events and the associated particle flux. Analyses are based on measurements from two current meters and two optical backscatterance sensors located at 30 and 100 cm above the bed. Data from these instruments and a pressure sensor were averaged over 7.5 min every hour. During the year of record, 41 distinct sediment-suspension events occurred (i.e., sustained suspended-sediment concentrations greater than 20 mg/l above background level at 100 cm above bed). Suspended-sediment events were associated with significant wave activity, tidal currents, and river discharge. The average duration of a sediment-suspension event was 3.1 days and varied from 0.7 to 8 days. During events, mean suspended-sediment concentrations of 110 mg/l were observed with peak hourly observations exceeding 1000 mg/l. Concentrations between events averaged 35 mg/l. The overall sediment flux for the period of record was directed seaward and southward. The distribution and magnitude of sediment-suspension events and particle flux showed a strong seasonality. For example, of the sediment transport during events, 98% of the net along-shelf, and 73% of the net across-shelf sediment transport occurred in the winter. Three major winter storms could account for 72% of the total along-shelf transport but only 10% of the across-shelf transport. The across-shelf flux was more evenly distributed over the year and occurred as a result of mean currents and very low-frequency seaward flows associated with mesoscale circulation patterns.

Estimates of suspended-sediment flux and bedform activity on the inner portion of the Eel continental shelf

Energetic waves, strong bottom currents, and relatively high rates of sediment discharge from the Eel River combined to produce large amounts of suspended-sediment transport on the inner continental shelf near the Eel River during the winter of 1995–1996. Bottom-boundary-layer (BBL) measurements at a depth of ∼50 m using the GEOPROBE tripod showed that the strongest near-bottom flows (combined wave and current speeds of over 1 m/s) and highest sediment concentrations (exceeding 2 g/l at ∼1.2 m above the bed) occurred during two storms, one in December 1995 and the other in February 1996. Discharge from the Eel River during these storms was estimated at between 2 and 4×10 3 m 3/s. Suspended-sediment flux (SSF) was measured 1.2 m above the bed and calculated throughout the BBL, by applying the tripod data to a shelf sediment-transport model. These results showed initially northward along-shelf SSF during the storms, followed by abrupt and persistent southward reversals. Along-shelf flux was more pronounced during and after the December storm than in February. Across-shelf SSF over the entire measurement period was decidedly seaward. This seaward transport could be responsible for surficial deposits of recent sediment on the outer shelf and upper continental slope in this region. Sediment ripples and larger bedforms were observed in the very fine to fine sand at 50-m depth using a sector-scanning sonar mounted on the tripod. Ripple wavelengths estimated from the sonar images were about 9 cm, which compared favorably with photographs of the bottom taken with a camera mounted on the tripod. The ripple patterns were stable during periods of low combined wave–current bottom stresses, but changed significantly during high-stress events, such as the February storm. Two different sonic altimeters recorded changes in bed elevation of 10 to 20 cm during the periods of measurement. These changes are thought to have been caused principally by the migration of low-amplitude, long-wavelength sand waves into the measurement area.

電話・物流・人流のODデータに基づく地域間関連の動的構造分析

電話・物流・人流のODデータに基づく地域間関連の動的構造分析