The effects of grouping fourth grade students into cooperative learning groups by learning patterns

The purpose of this study was to evaluate the performance of fourth grade students working in cooperative learning groups. Students worked in three cooperative learning groups in order to determine whether grouping students heterogeneously into cooperative learning groups based on individual students\u27 learning pattern would have a positive correlation with group and individual success. First students were grouped randomly and then homogeneously by learning pattern, and lastly heterogeneously by learning pattern. During each cooperative learning experience groups were expected to complete in-class group work. Students were then given a quiz and a test on the material covered during their cooperative learning groups. Moreover, students\u27 ability to cooperate and complete the assignments was observed and recorded. The findings of this study indicated that grouping fourth grade students into cooperative learning groups heterogeneously by learning patterns were overall more successful. The data indicated that students working in heterogeneous cooperative learning groups achieved a higher class average on in-class group assignments than the random and homogeneous groups based on learning pattern. However, not all data was statistically significant. Moreover, teacher-researcher\u27s observations revealed that student participation, involvement, and cooperation among group members during heterogeneous cooperative groups was significantly better in comparison to both homogeneous and random cooperative groups

Phenotypic and genetic differences in soil bacterial communities among successional stages

The association between soil microbes and plants can influence plant growth and survival as well as alter soil microbial community dynamics. The purpose of this study was to determine how the length of this interaction between plants and bacteria affects the bacterial soil community structure. Soil microbial communities associated with plant communities at different successional stages at the Santa Ana National Wildlife Refuge were investigated. The study sites included three revegetated sites (4 months, 21 months, and 221 months since revegetation) and a control site (native brush, never revegetated). Five soil samples were randomly collected at each site. Soil microbial communities at each site were characterized for density, nutrient utilization, and genetic profiles. There was no significant difference in density among the revegetated sites. Microbial communities associated with plant communities at earlier successional stages used significantly more nutrients and had higher activities than communities at later stages. Amplified Ribosomal DNA-Restriction Analysis (ARDRA) profiled the bacterial community to determine genetic differences in community structure within and among the sites. Restriction analysis using five restriction enzymes revealed more variation within and among bacterial communities associated with plant communities at earlier successional stages than at later stages. Soil microbial communities associated with younger revegetated sites were still in flux as they were undergoing succession and had not yet achieved a climax community

Flow Structure and Transport Characteristics of Feeding and Exchange Currents Generated by Upside-Down Cassiopea Jellyfish

Quantifying the flows generated by the pulsations of jellyfish bells is crucial for understanding the mechanics and efficiency of their swimming and feeding. Recent experimental and theoretical work has focused on the dynamics of vortices in the wakes of swimming jellyfish with relatively simple oral arms and tentacles. The significance of bell pulsations for generating feeding currents through elaborate oral arms and the consequences for particle capture are not as well understood. To isolate the generation of feeding currents from swimming, the pulsing kinematics and fluid flow around the benthic jellyfish Cassiopea spp. were investigated using a combination of videography, digital particle image velocimetry and direct numerical simulation. During the rapid contraction phase of the bell, fluid is pulled into a starting vortex ring that translates through the oral arms with peak velocities that can be of the order of 10 cm s–1. Strong shear flows are also generated across the top of the oral arms throughout the entire pulse cycle. A coherent train of vortex rings is not observed, unlike in the case of swimming oblate medusae such as Aurelia aurita. The phase-averaged flow generated by bell pulsations is similar to a vertical jet, with induced flow velocities averaged over the cycle of the order of 1–10 mm s–1. This introduces a strong near-horizontal entrainment of the fluid along the substrate and towards the oral arms. Continual flow along the substrate towards the jellyfish is reproduced by numerical simulations that model the oral arms as a porous Brinkman layer of finite thickness. This two-dimensional numerical model does not, however, capture the far-field flow above the medusa, suggesting that either the three-dimensionality or the complex structure of the oral arms helps to direct flow towards the central axis and up and away from the animal

Three-dimensional low Reynolds number flows near biological filtering and protective layers

Mesoscale filtering and protective layers are replete throughout the natural world. Within the body, arrays of extracellular proteins, microvilli, and cilia can act as both protective layers and mechanosensors. For example, blood flow profiles through the endothelial surface layer determine the amount of shear stress felt by the endothelial cells and may alter the rates at which molecules enter and exit the cells. Characterizing the flow profiles through such layers is therefore critical towards understanding the function of such arrays in cell signaling and molecular filtering. External filtering layers are also important to many animals and plants. Trichomes (the hairs or fine outgrowths on plants) can drastically alter both the average wind speed and profile near the leaf's surface, affecting the rates of nutrient and heat exchange. In this paper, dynamically scaled physical models are used to study the flow profiles outside of arrays of cylinders that represent such filtering and protective layers. In addition, numerical simulations using the Immersed Boundary Method are used to resolve the 3D flows within the layers. The experimental and computational results are compared to analytical results obtained by modeling the layer as a homogeneous porous medium with free flow above the layer. The experimental results show that the bulk flow is well described by simple analytical models. The numerical results show that the spatially averaged flow within the layer is well described by the Brinkman model. The numerical results also demonstrate that the flow can be highly 3D with fluid moving into and out of the layer. These effects are not described by the Brinkman model and may be significant for biologically relevant volume fractions. The results of this paper can be used to understand how variations in density and height of such structures can alter shear stresses and bulk flows.Comment: 28 pages, 10 figure

Has spring snowpack declined in the Washington Cascades?

Our best estimates of 1 April snow water equivalent (SWE) in the Cascade Mountains of Washington State indicate a substantial (roughly 15–35%) decline from mid-century to 2006, with larger declines at low elevations and smaller declines or increases at high elevations. This range of values includes estimates from observations and hydrologic modeling, reflects a range of starting points between about 1930 and 1970 and also reflects uncertainties about sampling. The most important sampling issue springs from the fact that half the 1 April SWE in the Cascades is found below about 1240 m, altitudes at which sampling was poor before 1945. Separating the influences of temperature and precipitation on 1 April SWE in several ways, it is clear that long-term trends are dominated by trends in temperature, whereas variability in precipitation adds "noise" to the time series. Consideration of spatial and temporal patterns of change rules out natural variations like the Pacific Decadal Oscillation as the sole cause of the decline. Regional warming has clearly played a role, but it is not yet possible to quantify how much of that regional warming is related to greenhouse gas emissions

Investigation of time-gap formulae on the CRE system using mouse tissue as a biological model.

The cumulative radiation effect (CRE) is one of several empirical scalar descriptions of biological effect which enable corrections to be made for gaps in radiotherapy treatment. Predictions of this theory were tested using mouse crypt regeneration and mouse skin as biological models. These experimental results are discussed in terms of the dependence of tissue regeneration potential during a gap on the biological effect achieved before the gap, and on gap length. A hypothesis is proposed to reconcile the apparent conflict between the two experiments. While the simple exponential gap formulation of the CRE is seen to be inadequate, insufficient data are available at present to modify it

Exploring agricultural land-use and childhood malaria associations in sub-Saharan Africa

Agriculture in Africa is rapidly expanding but with this comes potential disbenefits for the environment and human health. Here, we retrospectively assess whether childhood malaria in sub-Saharan Africa varies across differing agricultural land uses after controlling for socio-economic and environmental confounders. Using a multi-model inference hierarchical modelling framework, we found that rainfed cropland was associated with increased malaria in rural (OR 1.10, CI 1.03 – 1.18) but not urban areas, while irrigated or post flooding cropland was associated with malaria in urban (OR 1.09, CI 1.00 – 1.18) but not rural areas. In contrast, although malaria was associated with complete forest cover (OR 1.35, CI 1.24 – 1.47), the presence of natural vegetation in agricultural lands potentially reduces the odds of malaria depending on rural-urban context. In contrast, no associations with malaria were observed for natural vegetation interspersed with cropland (veg-dominant mosaic). Agricultural expansion through rainfed or irrigated cropland may increase childhood malaria in rural or urban contexts in sub-Saharan Africa but retaining some natural vegetation within croplands could help mitigate this risk and provide environmental co-benefits

Assessing Potential Winter Weather Response to Climate Change and Implications for Tourism in The U.S. Great Lakes and Midwest

Study Region: Eight U.S. states bordering the North American Laurentian Great Lakes. Study Focus: Variable Infiltration Capacity (VIC) model simulations, based on data from an en- semble of atmospheric-ocean general circulation models (AOGCMs) used for the Intergovernmental Panel on Climate Change\u27s (IPCC\u27s) Fifth Assessment Report (AR5), were used to quantify potential climate change impacts on winter weather and hydrology in the study re- gion and understand implications for its tourism sector. New Hydrologic Insights for the Region: By the 2080s, climate change could result in winters that are shorter by over a month, reductions of over a month in days with snow depths required for many kinds of winter recreation, declines in average holiday snow depths of 50 percent or more, and reductions in the percent area of the study region that would be considered viable for winter tourism from about 22 percent to 0.3 percent. Days with temperatures suitable for artificial snowmaking decline to less than a month annually, making it potentially less feasible as an adaptation strategy. All of the region\u27s current ski resorts are operating in areas that will become non-viable for winter tourism businesses under a high emissions scenario. Given the economic importance of the winter tourism industry in the study region, businesses and communities should consider climate change and potential adaptation strategies in their future planning and overall decision-making

Acceptance Criteria for Critical Software Based on Testability Estimates and Test Results

Testability is defined as the probability that a program will fail a test, conditional on the program containing some fault. In this paper, we show that statements about the testability of a program can be more simply described in terms of assumptions on the probability distribution of the failure intensity of the program. We can thus state general acceptance conditions in clear mathematical terms using Bayesian inference. We develop two scenarios, one for software for which the reliability requirements are that the software must be completely fault-free, and another for requirements stated as an upper bound on the acceptable failure probability