Dust control effectiveness of drywall sanding tools.

PubMed

Young-Corbett, Deborah E; Nussbaum, Maury A

2009-07-01

In this laboratory study, four drywall sanding tools were evaluated in terms of dust generation rates in the respirable and thoracic size classes. In a repeated measures study design, 16 participants performed simulated drywall finishing tasks with each of four tools: (1) ventilated sander, (2) pole sander, (3) block sander, and (4) wet sponge. Dependent variables of interest were thoracic and respirable breathing zone dust concentrations. Analysis by Friedman's Test revealed that the ventilated drywall sanding tool produced significantly less dust, of both size classes, than did the other three tools. The pole and wet sanders produced significantly less dust of both size classes than did the block sander. The block sander, the most commonly used tool in drywall finishing operations, produced significantly more dust of both size classes than did the other three tools. When compared with the block sander, the other tools offer substantial dust reduction. The ventilated tool reduced respirable concentrations by 88% and thoracic concentrations by 85%. The pole sander reduced respirable concentrations by 58% and thoracic by 50%. The wet sander produced reductions of 60% and 47% in the respirable and thoracic classes, respectively. Wet sponge sanders and pole sanders are effective at reducing breathing-zone dust concentrations; however, based on its superior dust control effectiveness, the ventilated sander is the recommended tool for drywall finishing operations.

The effect of class size in grades K-3 on adult earnings, employment, and disability status: evidence from a multi-center randomized controlled trial.

PubMed

Wilde, Elizabeth Ty; Finn, Jeremy; Johnson, Gretchen; Muennig, Peter

2011-11-01

Early education interventions have been forwarded as a means for reducing social disparities in income and health in adulthood. We explore whether a successful early education intervention, which occurred between 1985 and 1989, improved the employment rates, earnings and health of blacks relative to whites through 2008. We used data from Project STAR (Student Teacher Achievement Ratio), a four-year multi-center randomized controlled trial of reduced class sizes in Tennessee involving 11,601 students. Students were initially randomized within 79 schools to classes with 22-25 or 13-17 students. We linked subject records to Social Security Administration (SSA) earnings and disability data collected between 1997 and 2008-when the majority of subjects were between the ages of 18 and 28. We focused our analysis on annual, rather than cumulative, measures of earnings and employment because educational attainment after high school might reduce earnings through age 23. We considered three or more years of statistically significant positive (or negative) annual impacts to be a meaningful effect. Project STAR improved cognition and high school graduation rates. These benefits were primarily realized among low-income and minority students. These early education benefits did not translate into reduced disability claims in adulthood for treated subjects. However, exposure to small class size increased employment for blacks, and increased earnings for black males (p<0.05). Exposure to small classes also led to an increase in earnings for white males. However, white females exposed to small classes experienced a net decline in earnings and employment across the later years of follow up (p<0.05), offsetting any gains by white males. Exposure to small class size in grades K-3 appears to improve earnings and employment for black males and earnings for white males, while reducing employment and earnings among white females.

Reducing Class Size in New York City: Promise vs. Practice

ERIC Educational Resources Information Center

Farrie, Danielle; Johnson, Monete; Lecker, Wendy; Luhm, Theresa

2016-01-01

In the landmark school funding litigation, "Campaign for Fiscal Equity v. State" ("CFE"), the highest Court in New York recognized that reasonable class sizes are an essential element of a constitutional "sound basic education." In response to the rulings in the case, in 2007, the Legislature adopted a law mandating…

What Have Researchers Learned from Project STAR?

ERIC Educational Resources Information Center

Schanzenbach, Diane Whitmore

2007-01-01

Project STAR (Student/Teacher Achievement Ratio) was a large-scale randomized trial of reduced class sizes in kindergarten through the third grade. Because of the scope of the experiment, it has been used in many policy discussions. For example, the California statewide class-size-reduction policy was justified, in part, by the successes of…

Reducing Class Size: What Do We Know?

ERIC Educational Resources Information Center

Bascia, Nina

2010-01-01

This report provides an overview of findings from the research on primary class size reduction as a strategy to improve student learning. Its purpose is to provide a comprehensive and balanced picture of a very popular educational reform strategy that has often been seen as a "quick fix" for improving students' opportunities to learn in…

The Causal Effect of Class Size on Academic Achievement: Multivariate Instrumental Variable Estimators with Data Missing at Random

ERIC Educational Resources Information Center

Shin, Yongyun; Raudenbush, Stephen W.

2011-01-01

This article addresses three questions: Does reduced class size cause higher academic achievement in reading, mathematics, listening, and word recognition skills? If it does, how large are these effects? Does the magnitude of such effects vary significantly across schools? The authors analyze data from Tennessee's Student/Teacher Achievement Ratio…

The Nevada Class Size Reduction Evaluation Study, 1995.

ERIC Educational Resources Information Center

Nevada State Dept. of Education, Carson City.

A primary purpose for reducing the student-teacher ratio in the early grades is to make students more successful in their later years. This document contains two separate, but interrelated reports that examined two aspects of the 1989 Class Size Reduction (CSR) Act in Nevada. The Act called for a reduction in student-teacher ratios for selected…

Examining the effect of publishing of bill sizes to reduce information asymmetry on healthcare costs.

PubMed

Wong, C Y; Wu, E; Wong, T Y

2007-01-01

Information asymmetry has been offered as a reason for unnecessarily high costs in certain industries where significant information asymmetry traditionally exists between providers and consumers, such as healthcare. The purpose of this paper is to examine the impact of the introduction of publishing of bill size as a means to reduce healthcare costs. Specifically, we aim to examine if this initiative to decrease information asymmetry on healthcare prices between healthcare providers and patients, and between healthcare providers themselves, will lead to lower prices for patients. Bill size data of 29 commonly occurring diagnosis-related groups (DRGs) for two ward classes (B2 and C) over a 16- month period were studied. Each ward class was studied separately, i.e. involving 58 DRG data sets. The mean bill size data as well as that of 50th and 90th percentile bill sizes were examined. The study involved some 46,000 inpatient episodes which occurred in the five public sector acute general hospitals of Singapore. Mean prices dropped by 4.14 percent and 9.64 percent for B2 and C classes, respectively. 50 out of 58 DRG data sets showed a drop in prices. Bill sizes at the 50th percentile dropped by 7.95 percent and 10.12 percent for B2 and C classes, respectively; while at the 90th percentile, the corresponding figures were decreases of 8.01 percent and 11.4 percent for the two ward classes. The act of publishing bill sizes has led to less information asymmetry among providers, thereby facilitating more competitive behaviour among hospitals and lower bill sizes.

Will Parents and Teachers Get on the Bandwagon To Reduce Class Size?

ERIC Educational Resources Information Center

Johnson, Jean

2002-01-01

Presents several questions and answers about small high schools based on Public Agenda (a nonprofit research organization in New York City) survey of 920 public high school teachers and 801 parents of students enrolled in public high schools. Discusses community issues related to reducing school size. (PKP)

School Facility Recommendations for Class Size Reduction.

ERIC Educational Resources Information Center

Evans, Ann M.

The California Department of Education encourages its school districts to make every effort to reduce classroom size and maintain the physical size of 960 square feet for elementary schools and 1,350 square feet for kindergartens. This report examines the Code of Regulations relative to classroom size in elementary, kindergarten, and special…

Fukunaga-Koontz transform based dimensionality reduction for hyperspectral imagery

NASA Astrophysics Data System (ADS)

Ochilov, S.; Alam, M. S.; Bal, A.

2006-05-01

Fukunaga-Koontz Transform based technique offers some attractive properties for desired class oriented dimensionality reduction in hyperspectral imagery. In FKT, feature selection is performed by transforming into a new space where feature classes have complimentary eigenvectors. Dimensionality reduction technique based on these complimentary eigenvector analysis can be described under two classes, desired class and background clutter, such that each basis function best represent one class while carrying the least amount of information from the second class. By selecting a few eigenvectors which are most relevant to desired class, one can reduce the dimension of hyperspectral cube. Since the FKT based technique reduces data size, it provides significant advantages for near real time detection applications in hyperspectral imagery. Furthermore, the eigenvector selection approach significantly reduces computation burden via the dimensionality reduction processes. The performance of the proposed dimensionality reduction algorithm has been tested using real-world hyperspectral dataset.

Teaching Large Classes in Higher Education. How To Maintain Quality with Reduced Resources.

ERIC Educational Resources Information Center

Gibbs, Graham, Ed.; Jenkins, Alan, Ed.

This publication seeks to give practical assistance to teachers and administrators responsible for teaching large classes at collges and universities in the United Kingdom. Areas covered include class size, problems related to learning and teaching, teaching strategies in specific disciplines, field study experience and other subjects. The 12…

Intensive Education: How It Affects Teachers' and Students' Work Conditions.

ERIC Educational Resources Information Center

Fallon, Karin

This qualitative study of a high school using intensive education shows how teaching and learning were improved when teachers taught and students attended one class daily for 6 weeks. Intensive education is an alternative scheduling and organizational format that reduces class size and extends class length by having teachers and students in one…

Class-Size Reduction Program Evaluation, 2000-2001. A Report to the North Carolina Department of Public Instruction.

ERIC Educational Resources Information Center

Speas, Carol

This study examined the impact of the second year of the federal class-size reduction (CSR) program in the Wake County Public School System (WCPSS), North Carolina. The 23 participating schools in the WCPSS had from 22% to 51% of their students receiving free or reduced-price lunches. In the second year, the CSR program was expanded from grades 1…

The effects of host size and temperature on the emergence of Echinoparyphium recurvatum cercariae from Lymnaea peregra under natural light conditions.

PubMed

Morley, N J; Adam, M E; Lewis, J W

2010-09-01

The production of cercariae from their snail host is a fundamental component of transmission success in trematodes. The emergence of Echinoparyphium recurvatum (Trematoda: Echinostomatidae) cercariae from Lymnaea peregra was studied under natural sunlight conditions, using naturally infected snails of different sizes (10-17 mm) within a temperature range of 10-29 degrees C. There was a single photoperiodic circadian cycle of emergence with one peak, which correlated with the maximum diffuse sunlight irradiation. At 21 degrees C the daily number of emerging cercariae increased with increasing host snail size, but variations in cercarial emergence did occur between both individual snails and different days. There was only limited evidence of cyclic emergence patterns over a 3-week period, probably due to extensive snail mortality, particularly those in the larger size classes. Very few cercariae emerged in all snail size classes at the lowest temperature studied (10 degrees C), but at increasingly higher temperatures elevated numbers of cercariae emerged, reaching an optimum between 17 and 25 degrees C. Above this range emergence was reduced. At all temperatures more cercariae emerged from larger snails. Analysis of emergence using the Q10 value, a measure of physiological processes over temperature ranges, showed that between 10 and 21 degrees C (approximately 15 degrees C) Q10 values exceeded 100 for all snail size classes, indicating a substantially greater emergence than would be expected for normal physiological rates. From 14 to 25 degrees C (approximately 20 degrees C) cercarial emergence in most snail size classes showed little change in Q10, although in the smallest size class emergence was still substantially greater than the typical Q10 increase expected over this temperature range. At the highest range of 21-29 degrees C (approximately 25 degrees C), Q10 was much reduced. The importance of these results for cercarial emergence under global climate change is discussed.

Size-dependent survival of brook trout Salvelinus fontinalis in summer: effects of water temperature and stream flow.

PubMed

Xu, C L; Letcher, B H; Nislow, K H

2010-06-01

A 5 year individual-based data set was used to estimate size-specific survival rates in a wild brook trout Salvelinus fontinalis population in a stream network encompassing a mainstem and three tributaries (1.5-6 m wetted width), western Massachusetts, U.S.A. The relationships between survival in summer and temperature and flow metrics derived from continuous monitoring data were then tested. Increased summer temperatures significantly reduced summer survival rates for S. fontinalis in almost all size classes in all four sites throughout the network. In contrast, extreme low summer flows reduced survival of large fish, but only in small tributaries, and had no significant effects on fish in smaller size classes in any location. These results provide direct evidence of a link between season-specific survival and environmental factors likely to be affected by climate change and have important consequences for the management of both habitats and populations.

Factors associated with long-term species composition in dry tropical forests of Central India

NASA Astrophysics Data System (ADS)

Agarwala, M.; DeFries, R. S.; Qureshi, Q.; Jhala, Y. V.

2016-10-01

The long-term future of species composition in forests depends on regeneration. Many factors can affect regeneration, including human use, environmental conditions, and species’ traits. This study examines the influence of these factors in a tropical deciduous forest of Central India, which is heavily used by local, forest-dependent residents for livestock grazing, fuel-wood extraction, construction and other livelihood needs. We measure size-class proportions (the ratio of abundance of a species at a site in a higher size class to total abundance in both lower and higher size classes) for 39 tree species across 20 transects at different intensities of human use. The size-class proportions for medium to large trees and for small to medium-sized trees were negatively associated with species that are used for local construction, while size class proportions for saplings to small trees were positively associated with those species that are fire resistant and negatively associated with livestock density. Results indicate that grazing and fire prevent non-fire resistant species from reaching reproductive age, which can alter the long term composition and future availability of species that are important for local use and ecosystem services. Management efforts to reduce fire and forest grazing could reverse these impacts on long-term forest composition.

Breaking Bad Habits: Navigating the Financial Crisis

ERIC Educational Resources Information Center

Jones, Dennis; Wellman, Jane

2010-01-01

The "Great Recession" of 2009 has brought an unprecedented level of financial chaos to public higher education in America. Programs are being reduced, furloughs and layoffs are widespread, class sizes are increasing, sections are being cut, and students can't get into classes needed for graduation. Reports of budget cuts in public…

[Effective size of subpopulations in early-run sockeye salmon Oncorhynchus nerka from Azabach'e Lake (Kamchatka): the effect of relative reproductive success of different-year cohorts].

PubMed

Efremov, V V

2004-05-01

The effect of variation in reproductive success of cohorts of different year of birth (within generation) on the effective subpopulation (breeding group) size in early-run sockeye salmon Oncorhynchus nerka from Azabach'e Lake (Kamchatka). The annual variation in census size and overlapping of year classes reduced the ratio of the effective subpopulation size to the census size by 7 to 88% in different subpopulations. The total effect of the variance of reproductive success in individual years and the variance of reproductive success of different cohorts reduced the effective size/census size ratio by 68-96%.

Class IA phosphoinositide 3-kinase regulates heart size and physiological cardiac hypertrophy.

PubMed

Luo, Ji; McMullen, Julie R; Sobkiw, Cassandra L; Zhang, Li; Dorfman, Adam L; Sherwood, Megan C; Logsdon, M Nicole; Horner, James W; DePinho, Ronald A; Izumo, Seigo; Cantley, Lewis C

2005-11-01

Class I(A) phosphoinositide 3-kinases (PI3Ks) are activated by growth factor receptors, and they regulate, among other processes, cell growth and organ size. Studies using transgenic mice overexpressing constitutively active and dominant negative forms of the p110alpha catalytic subunit of class I(A) PI3K have implicated the role of this enzyme in regulating heart size and physiological cardiac hypertrophy. To further understand the role of class I(A) PI3K in controlling heart growth and to circumvent potential complications from the overexpression of dominant negative and constitutively active proteins, we generated mice with muscle-specific deletion of the p85alpha regulatory subunit and germ line deletion of the p85beta regulatory subunit of class I(A) PI3K. Here we show that mice with cardiac deletion of both p85 subunits exhibit attenuated Akt signaling in the heart, reduced heart size, and altered cardiac gene expression. Furthermore, exercise-induced cardiac hypertrophy is also attenuated in the p85 knockout hearts. Despite such defects in postnatal developmental growth and physiological hypertrophy, the p85 knockout hearts exhibit normal contractility and myocardial histology. Our results therefore provide strong genetic evidence that class I(A) PI3Ks are critical regulators for the developmental growth and physiological hypertrophy of the heart.

The effects of next-day class characteristics on alcohol demand in college students.

PubMed

Berman, Hanna L; Martinetti, Margaret P

2017-06-01

Behavioral economic principles have been useful for addressing strategies to reduce alcohol consumption among college students. For example, academic variables (such as class schedule or academic rigor) have been found to affect alcohol demand assessed with a hypothetical alcohol purchase task (APT). The present studies used the APT to address the effects of 2 academic variables: next-day course level (no class, introductory level or upper level) and class size (no class, 30-student or 12-student). In each of 2 experiments, undergraduate participants read a description of a drinking context (either a no-class control version or 1 of the academic constraint conditions) and were asked to indicate how many drinks they would purchase at a variety of prices. Hursh and Silberberg's (2008) exponential demand equation was used to determine intensity and elasticity of demand, and Hursh and Roma's (2015) essential value (EV) parameter was calculated to assess essential value. In both experiments, a next-day class reduced alcohol demand, and alcohol consumption decreased as drink price increased. The presence of a smaller next-day class reduced alcohol demand compared with a larger next-day class; however, course level did not differentially affect alcohol demand. These results suggest that smaller next-day classes may reduce alcohol demand among college students and also provide initial evidence for the reliability of EV across studies. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

PBL Group Autonomy in a High School Environmental Science Class

ERIC Educational Resources Information Center

Weiss, D. Mark; Belland, Brian R.

2018-01-01

With increasing class sizes, teachers and facilitators alike hope for learning groups where students work together in self-contained and autonomous ways requiring reduced teacher support. Yet many instructors find the idea of developing independent learning in small groups to be elusive particularly in K-12 settings (Ertmer and Simons in…

Reliability and agreement in student ratings of the class environment.

PubMed

Nelson, Peter M; Christ, Theodore J

2016-09-01

The current study estimated the reliability and agreement of student ratings of the classroom environment obtained using the Responsive Environmental Assessment for Classroom Teaching (REACT; Christ, Nelson, & Demers, 2012; Nelson, Demers, & Christ, 2014). Coefficient alpha, class-level reliability, and class agreement indices were evaluated as each index provides important information for different interpretations and uses of student rating scale data. Data for 84 classes across 29 teachers in a suburban middle school were sampled to derive reliability and agreement indices for the REACT subscales across 4 class sizes: 25, 20, 15, and 10. All participating teachers were White and a larger number of 6th-grade classes were included (42%) relative to 7th- (33%) or 8th- (23%) grade classes. Teachers were responsible for a variety of content areas, including language arts (26%), science (26%), math (20%), social studies (19%), communications (6%), and Spanish (3%). Coefficient alpha estimates were generally high across all subscales and class sizes (α = .70-.95); class-mean estimates were greatly impacted by the number of students sampled from each class, with class-level reliability values generally falling below .70 when class size was reduced from 25 to 20. Further, within-class student agreement varied widely across the REACT subscales (mean agreement = .41-.80). Although coefficient alpha and test-retest reliability are commonly reported in research with student rating scales, class-level reliability and agreement are not. The observed differences across coefficient alpha, class-level reliability, and agreement indices provide evidence for evaluating students' ratings of the class environment according to their intended use (e.g., differentiating between classes, class-level instructional decisions). (PsycINFO Database Record (c) 2016 APA, all rights reserved).

A microphysical parameterization of aqSOA and sulfate formation in clouds

NASA Astrophysics Data System (ADS)

McVay, Renee; Ervens, Barbara

2017-07-01

Sulfate and secondary organic aerosol (cloud aqSOA) can be chemically formed in cloud water. Model implementation of these processes represents a computational burden due to the large number of microphysical and chemical parameters. Chemical mechanisms have been condensed by reducing the number of chemical parameters. Here an alternative is presented to reduce the number of microphysical parameters (number of cloud droplet size classes). In-cloud mass formation is surface and volume dependent due to surface-limited oxidant uptake and/or size-dependent pH. Box and parcel model simulations show that using the effective cloud droplet diameter (proportional to total volume-to-surface ratio) reproduces sulfate and aqSOA formation rates within ≤30% as compared to full droplet distributions; other single diameters lead to much greater deviations. This single-class approach reduces computing time significantly and can be included in models when total liquid water content and effective diameter are available.

Laying a Foundation for Lifelong Learning: Case Studies of E-Assessment in Large 1st-Year Classes

ERIC Educational Resources Information Center

Nicol, David

2007-01-01

Concerns about noncompletion and the quality of the 1st-year student experience have been linked to recent changes in higher education such as modularisation, increased class sizes, greater diversity in the student intake and reduced resources. Improving formative assessment and feedback processes is seen as one way of addressing academic failure,…

[Effects of forest gap size on the growth and form quality of Taxus wallichina var. mairei in Cunninghamia lanceolata forests].

PubMed

Ou, Jian de; Wu, Zhi Zhuang; Luo, Ning

2016-10-01

In order to clarify the effects of forest gap size on the growth and stem form quality of Taxus wallichina var. mairei and effectiveness of the precious timbers cultivation, 25 sample plots in Cunninghamia lanceolata forest gaps were established in Mingxi County, Fujian Province, China to determine the indices of the growth, stem form and branching indices of T. wallichina var. mairei seedlings. The relationships between the gap size and growth, stem form and branching were investigated. The 25 sample plots were located at five microhabitats which were classified based on gap size as follows: Class1, 2, 3, 4 and 5, which had a gap size of 25-50 m 2 , 50-75 m 2 , 75-100 m 2 , 100-125 m 2 and 125-150 m 2 , respectively. The evaluation index system of precious timbers was built by using hierarchical analysis. The 5 classes of forest gaps were evaluated comprehensively by using the multiobjective decision making method. The results showed that gap size significantly affected 11 indices, i.e., height, DBH, crown width, forking rate, stem straightness, stem fullness, taperingness, diameter height ratio, height under living branch, interval between branches, and max-branch base diameter. Class1and 2 both significantly promoted the growth of height, DBH and crown width, and both significantly inhibited forking rate and taperingness, and improved stem straightness. Class2 significantly improved stem fullness and diameter height ratio. Class1and 2 significantly improved height under living branch and reduced max-branch base diameter. Class 1 significantly increased interval between branches. Class1and2 significantly improved the comprehensive evaluation score of precious timbers. This study suggested that controlled cutting intensity could be used to create forest gaps of 25-75 m 2 , which improved the precious timber cultivating process of T. wallichina var. mairei in C. lanceolata forests.

Long-term efficacy of diameter-limit cutting to reduce mountain pine beetle-caused tree mortality in a lodgepole pine forest

Treesearch

J. C. Vandygriff; E. Hansen; Barbara Bentz; K. K. Allen; G. D. Amman; L. A. Rasmussen

2015-01-01

Mountain pine beetle, Dendroctonus ponderosae Hopkins, is the most significant mortality agent in pine forests of western North America. Silvicultural treatments that reduce the number of susceptible host trees, alter age and size class distributions, and diversify species composition are considered viable, long-term options for reducing stand susceptibility...

Epicormic branching on hardwood trees bordering forest openings

Treesearch

G.R., Jr. Trimble; Donald W. Seegrist; Donald W. Seegrist

1973-01-01

Epicormic branching in hardwoods can degrade logs and reduce the dollar returns from growing trees. A study made around clearcut openings of various sizes showed that the following variables were related to the degree of epicormic branching on trees bordering the openings: size of opening, species, tree dominance class, exposure of tree bole, and position on tree bole...

Sparse Solutions for Single Class SVMs: A Bi-Criterion Approach

NASA Technical Reports Server (NTRS)

Das, Santanu; Oza, Nikunj C.

2011-01-01

In this paper we propose an innovative learning algorithm - a variation of One-class nu Support Vector Machines (SVMs) learning algorithm to produce sparser solutions with much reduced computational complexities. The proposed technique returns an approximate solution, nearly as good as the solution set obtained by the classical approach, by minimizing the original risk function along with a regularization term. We introduce a bi-criterion optimization that helps guide the search towards the optimal set in much reduced time. The outcome of the proposed learning technique was compared with the benchmark one-class Support Vector machines algorithm which more often leads to solutions with redundant support vectors. Through out the analysis, the problem size for both optimization routines was kept consistent. We have tested the proposed algorithm on a variety of data sources under different conditions to demonstrate the effectiveness. In all cases the proposed algorithm closely preserves the accuracy of standard one-class nu SVMs while reducing both training time and test time by several factors.

Myosins XI-K, XI-1, and XI-2 are required for development of pavement cells, trichomes, and stigmatic papillae in Arabidopsis

PubMed Central

2012-01-01

Background The positioning and dynamics of vesicles and organelles, and thus the growth of plant cells, is mediated by the acto-myosin system. In Arabidopsis there are 13 class XI myosins which mediate vesicle and organelle transport in different cell types. So far the involvement of five class XI myosins in cell expansion during the shoot and root development has been shown, three of which, XI-1, XI-2, and XI-K, are essential for organelle transport. Results Simultaneous depletion of Arabidopsis class XI myosins XI-K, XI-1, and XI-2 in double and triple mutant plants affected the growth of several types of epidermal cells. The size and shape of trichomes, leaf pavement cells and the elongation of the stigmatic papillae of double and triple mutant plants were affected to different extent. Reduced cell size led to significant size reduction of shoot organs in the case of triple mutant, affecting bolt formation, flowering time and fertility. Phenotype analysis revealed that the reduced fertility of triple mutant plants was caused by delayed or insufficient development of pistils. Conclusions We conclude that the class XI myosins XI-K, XI-1 and XI-2 have partially redundant roles in the growth of shoot epidermis. Myosin XI-K plays more important role whereas myosins XI-1 and XI-2 have minor roles in the determination of size and shape of epidermal cells, because the absence of these two myosins is compensated by XI-K. Co-operation between myosins XI-K and XI-2 appears to play an important role in these processes. PMID:22672737

Object recognition of real targets using modelled SAR images

NASA Astrophysics Data System (ADS)

Zherdev, D. A.

2017-12-01

In this work the problem of recognition is studied using SAR images. The algorithm of recognition is based on the computation of conjugation indices with vectors of class. The support subspaces for each class are constructed by exception of the most and the less correlated vectors in a class. In the study we examine the ability of a significant feature vector size reduce that leads to recognition time decrease. The images of targets form the feature vectors that are transformed using pre-trained convolutional neural network (CNN).

Transcriptome assembly and candidate genes involved in nutritional programming in the swordtail fish Xiphophorus multilineatus.

PubMed

Lu, Yuan; Klimovich, Charlotte M; Robeson, Kalen Z; Boswell, William; Ríos-Cardenas, Oscar; Walter, Ronald B; Morris, Molly R

2017-01-01

Nutritional programming takes place in early development. Variation in the quality and/or quantity of nutrients in early development can influence long-term health and viability. However, little is known about the mechanisms of nutritional programming. The live-bearing fish Xiphophorus multilineatus has the potential to be a new model for understanding these mechanisms, given prior evidence of nutritional programming influencing behavior and juvenile growth rate. We tested the hypotheses that nutritional programming would influence behaviors involved in energy homeostasis as well gene expression in X. multilineatus. We first examined the influence of both juvenile environment (varied in nutrition and density) and adult environment (varied in nutrition) on behaviors involved in energy acquisition and energy expenditure in adult male X. multilineatus . We also compared the behavioral responses across the genetically influenced size classes of males. Males stop growing at sexual maturity, and the size classes of can be identified based on phenotypes (adult size and pigment patterns). To study the molecular signatures of nutritional programming, we assembled a de novo transcriptome for X. multilineatus using RNA from brain, liver, skin, testis and gonad tissues, and used RNA-Seq to profile gene expression in the brains of males reared in low quality (reduced food, increased density) and high quality (increased food, decreased density) juvenile environments. We found that both the juvenile and adult environments influenced the energy intake behavior, while only the adult environment influenced energy expenditure. In addition, there were significant interactions between the genetically influenced size classes and the environments that influenced energy intake and energy expenditure, with males from one of the four size classes (Y-II) responding in the opposite direction as compared to the other males examined. When we compared the brains of males of the Y-II size class reared in a low quality juvenile environment to males from the same size class reared in high quality juvenile environment, 131 genes were differentially expressed, including metabolism and appetite master regulator agrp gene. Our study provides evidence for nutritional programming in X. multilineatus , with variation across size classes of males in how juvenile environment and adult diet influences behaviors involved in energy homeostasis. In addition, we provide the first transcriptome of X. multilineatus , and identify a group of candidate genes involved in nutritional programming.

Class-Size Effects in Secondary School

ERIC Educational Resources Information Center

Krassel, Karl Fritjof; Heinesen, Eskil

2014-01-01

We analyze class-size effects on academic achievement in secondary school in Denmark exploiting an institutional setting where pupils cannot predict class size prior to enrollment, and where post-enrollment responses aimed at affecting realized class size are unlikely. We identify class-size effects combining a regression discontinuity design with…

Forest inventory using multistage sampling with probability proportional to size. [Brazil

NASA Technical Reports Server (NTRS)

Parada, N. D. J. (Principal Investigator); Lee, D. C. L.; Hernandezfilho, P.; Shimabukuro, Y. E.; Deassis, O. R.; Demedeiros, J. S.

1984-01-01

A multistage sampling technique, with probability proportional to size, for forest volume inventory using remote sensing data is developed and evaluated. The study area is located in the Southeastern Brazil. The LANDSAT 4 digital data of the study area are used in the first stage for automatic classification of reforested areas. Four classes of pine and eucalypt with different tree volumes are classified utilizing a maximum likelihood classification algorithm. Color infrared aerial photographs are utilized in the second stage of sampling. In the third state (ground level) the time volume of each class is determined. The total time volume of each class is expanded through a statistical procedure taking into account all the three stages of sampling. This procedure results in an accurate time volume estimate with a smaller number of aerial photographs and reduced time in field work.

Argentine tango dance compared to mindfulness meditation and a waiting-list control: a randomised trial for treating depression.

PubMed

Pinniger, Rosa; Brown, Rhonda F; Thorsteinsson, Einar B; McKinley, Patricia

2012-12-01

To determine whether tango dancing is as effective as mindfulness meditation in reducing symptoms of psychological stress, anxiety and depression, and in promoting well-being. This study employed analysis of covariance (ANCOVA) and multiple regression analysis. Ninety-seven people with self-declared depression were randomised into tango dance or mindfulness meditation classes, or to control/waiting-list. classes were conducted in a venue suitable for both activities in the metropolitan area of Sydney, Australia. Participants completed six-week programmes (1½h/week of tango or meditation). The outcome measures were assessed at pre-test and post-test. Depression, Anxiety and Stress Scale; The Self Esteem Scale; Satisfaction with Life Scale, and Mindful Attention Awareness Scale. Sixty-six participants completed the program and were included in the statistical analysis. Depression levels were significantly reduced in the tango (effect size d=0.50, p=.010), and meditation groups (effect size d=0.54, p=.025), relative to waiting-list controls. Stress levels were significantly reduced only in the tango group (effect size d=0.45, p=.022). Attending tango classes was a significant predictor for the increased levels of mindfulness R(2)=.10, adjusted R(2)=.07, F (2,59)=3.42, p=.039. Mindfulness-meditation and tango dance could be effective complementary adjuncts for the treatment of depression and/or inclusion in stress management programmes. Subsequent trials are called to explore the therapeutic mechanisms involved. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

The Determinants of Parental Effort in Education Production: Do Parents Respond to Changes in Class Size?

ERIC Educational Resources Information Center

Bonesronning, Hans

2004-01-01

The present paper supplements the traditional class size literature by exploring the causal relationship between class size and parental effort in education production. Class size variation that is exogenous to parental effort comes from interaction between enrollment and a maximum class size rule of 30 students in the lower secondary school in…

Class Size and Education in England Evidence Report. Research Report. DFE-RR169

ERIC Educational Resources Information Center

Department for Education, 2011

2011-01-01

This report gives an overview of the existing evidence base on class size and education in England. In particular, it considers how class sizes have changed over time; the impact of the increase in birth rate on pupil numbers and how this could affect the teacher requirement and class sizes; and the impact of class size on educational outcomes.…

Applications of remote sensing, volume 1

NASA Technical Reports Server (NTRS)

Landgrebe, D. A. (Principal Investigator)

1977-01-01

The author has identified the following significant results. ECHO successfully exploits the redundancy of states characteristics of sampled imagery of ground scenes to achieve better classification accuracy, reduce the number of classifications required, and reduce the variability of classification results. The information required to produce ECHO classifications are cell size, cell homogeneity, cell-to-field annexation parameters, input data, and a class conditional marginal density statistics deck.

Opportunities for Low Cost Titanium in Reduced Fuel Consumption, Improved Emissions, and Enhanced Durability Heavy Duty Vehicles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kraft, E.H.

2002-07-22

The purpose of this study was to determine which components of heavy-duty highway vehicles are candidates for the substitution of titanium materials for current materials if the cost of those Ti components is very significantly reduced from current levels. The processes which could be used to produce those low cost components were also investigated. Heavy-duty highway vehicles are defined as all trucks and busses included in Classes 2C through 8. These include heavy pickups and vans above 8,500 lbs. GVWR, through highway tractor trailers. Class 8 is characterized as being a very cyclic market, with ''normal'' year volume, such asmore » in 2000, of approximately 240,000 new vehicles. Classes 3-7 are less cyclic, with ''normal'' i.e., year 2000, volume totaling approximately 325,000 new vehicles. Classes 3-8 are powered about 88.5% by diesel engines, and Class 2C at very roughly 83% diesel. The engine portion of the study therefore focused on diesels. Vehicle production volumes were used in estimates of the market size for candidate components.« less

A Heuristics Approach for Classroom Scheduling Using Genetic Algorithm Technique

NASA Astrophysics Data System (ADS)

Ahmad, Izah R.; Sufahani, Suliadi; Ali, Maselan; Razali, Siti N. A. M.

2018-04-01

Reshuffling and arranging classroom based on the capacity of the audience, complete facilities, lecturing time and many more may lead to a complexity of classroom scheduling. While trying to enhance the productivity in classroom planning, this paper proposes a heuristic approach for timetabling optimization. A new algorithm was produced to take care of the timetabling problem in a university. The proposed of heuristics approach will prompt a superior utilization of the accessible classroom space for a given time table of courses at the university. Genetic Algorithm through Java programming languages were used in this study and aims at reducing the conflicts and optimizes the fitness. The algorithm considered the quantity of students in each class, class time, class size, time accessibility in each class and lecturer who in charge of the classes.

Mass Instruction or Higher Learning? The Impact of College Class Size on Student Retention and Graduation

ERIC Educational Resources Information Center

Bettinger, Eric P.; Long, Bridget Terry

2018-01-01

This paper measures the effects of collegiate class size on college retention and graduation. Class size is a perennial issue in research on primary and secondary schooling. Few researchers have focused on the causal impacts of collegiate class size, however. Whereas college students have greater choice of classes, selection problems and nonrandom…

Multi-Positioning Mathematics Class Size: Teachers' Views

ERIC Educational Resources Information Center

Handal, Boris; Watson, Kevin; Maher, Marguerite

2015-01-01

This paper explores mathematics teachers' perceptions about class size and the impact class size has on teaching and learning in secondary mathematics classrooms. It seeks to understand teachers' views about optimal class sizes and their thoughts about the education variables that influence these views. The paper draws on questionnaire responses…

Promoting Physical Education: The Link to Academic Achievement

ERIC Educational Resources Information Center

Smith, Nicole J.; Lounsbery, Monica

2009-01-01

Quality physical education is recognized for its health-related benefits and should be supported as an integral component of every school's curriculum. Unfortunately, quality physical education is not easily established or maintained. Many physical education programs face challenges such as reduced staff, large class sizes, inadequate facilities…

Do Class Size Effects Differ across Grades?

ERIC Educational Resources Information Center

Nandrup, Anne Brink

2016-01-01

This paper contributes to the class size literature by analysing whether short-run class size effects are constant across grade levels in compulsory school. Results are based on administrative data on all pupils enrolled in Danish public schools. Identification is based on a government-imposed class size cap that creates exogenous variation in…

The Synergy of Class Size Reduction and Classroom Quality

ERIC Educational Resources Information Center

Graue, Elizabeth; Rauscher, Erica; Sherfinski, Melissa

2009-01-01

A contextual approach to understanding class size reduction includes attention to both educational inputs and processes. Based on our study of a class size reduction program in Wisconsin we explore the following question: How do class size reduction and classroom quality interact to produce learning opportunities in early elementary classrooms? To…

Online Class Size, Note Reading, Note Writing and Collaborative Discourse

ERIC Educational Resources Information Center

Qiu, Mingzhu; Hewitt, Jim; Brett, Clare

2012-01-01

Researchers have long recognized class size as affecting students' performance in face-to-face contexts. However, few studies have examined the effects of class size on exact reading and writing loads in online graduate-level courses. This mixed-methods study examined relationships among class size, note reading, note writing, and collaborative…

Alternative Fuel Reduction Treatments in the Gunflint Corridor of the Superior National Forest: Second year results and sampling recommendations

Treesearch

Daniel W. Gilmore; Douglas N. Kastendick; John C. Zasada; Paula J. Anderson

2003-01-01

Fuel loadings need to be considered in two ways: 1) the total fuel loadings of various size classes and 2) their distribution across a site. Fuel treatments in this study affected both. We conclude that 1) mechanical treatments of machine piling and salvage logging reduced fine and heavy fuel loadings and 2) prescribed fire was successful in reducing fine fuel...

Wave rotor-enhanced gas turbine engines

NASA Technical Reports Server (NTRS)

Welch, Gerard E.; Scott, Jones M.; Paxson, Daniel E.

1995-01-01

The benefits of wave rotor-topping in small (400 to 600 hp-class) and intermediate (3000 to 4000 hp-class) turboshaft engines, and large (80,000 to 100,000 lb(sub f)-class) high bypass ratio turbofan engines are evaluated. Wave rotor performance levels are calculated using a one-dimensional design/analysis code. Baseline and wave rotor-enhanced engine performance levels are obtained from a cycle deck in which the wave rotor is represented as a burner with pressure gain. Wave rotor-toppings is shown to significantly enhance the specific fuel consumption and specific power of small and intermediate size turboshaft engines. The specific fuel consumption of the wave rotor-enhanced large turbofan engine can be reduced while operating at significantly reduced turbine inlet temperature. The wave rotor-enhanced engine is shown to behave off-design like a conventional engine. Discussion concerning the impact of the wave rotor/gas turbine engine integration identifies tenable technical challenges.

Class Size Effects on Fourth-Grade Mathematics Achievement: Evidence from TIMSS 2011

ERIC Educational Resources Information Center

Li, Wei; Konstantopoulos, Spyros

2016-01-01

Class size reduction policies have been widely implemented around the world in recent years. However, findings about the effects of class size on student achievement have been mixed. This study examines class size effects on fourth-grade mathematics achievement in 14 European countries using data from TIMSS (Trends in International Mathematics and…

Making Sense of Continuing and Renewed Class-Size Findings and Interest.

ERIC Educational Resources Information Center

Achilles, C. M.; Finn, J. D.

In this paper, the authors examine several factors related to class size. The purpose of the presentation is to: (1) trace the evolution of class-size research; (2) briefly describe the Student Achievement Ratio (STAR) class-size experiment; (3) summarize the early and the later student outcomes of STAR participants; (4) outline the…

Primary Class Size Reduction: How Policy Space, Physical Space, and Spatiality Shape What Happens in Real Schools

ERIC Educational Resources Information Center

Bascia, Nina; Faubert, Brenton

2012-01-01

This article reviews the literature base on class size reduction and proposes a new analytic framework that we believe provides practically useful explanations of how primary class size reduction works. It presents descriptions of classroom practice and grounded explanations for how class size reduction affects educational core activities by…

Class Size Effects on Mathematics Achievement in Cyprus: Evidence from TIMSS

ERIC Educational Resources Information Center

Konstantopoulos, Spyros; Shen, Ting

2016-01-01

Class size reduction has been viewed as one school mechanism that can improve student achievement. Nonetheless, the literature has reported mixed findings about class size effects. We used 4th- and 8th-grade data from TIMSS 2003 and 2007 to examine the association between class size and mathematics achievement in public schools in Cyprus. We…

Class-Size Policy: The STAR Experiment and Related Class-Size Studies. NCPEA Policy Brief. Volume 1, Number 2

ERIC Educational Resources Information Center

Achilles, Charles M.

2012-01-01

This brief summarizes findings on class size from over 25 years of work on the Tennessee Student Teacher Achievement Ratio (STAR) randomized, longitudinal experiment, and other Class-Size Reduction (CSR) studies throughout the United States, Australia, Hong Kong, Sweden, Great Britain, and elsewhere. The brief concludes with recommendations. The…

Spatial and temporal variability in estuary habitat use by American alligators

USGS Publications Warehouse

Fujisaki, Ikuko; Hart, Kristen M.; Cherkiss, Michael S.; Mazzotti, Frank J.; Beauchamp, Jeffrey S.; Jeffery, Brian M.; Brandt, Laura A.

2016-01-01

Estuarine habitat occupied by Alligator mississippiensis, a primarily freshwater species, is spatially and temporally heterogeneous largely due to a salinity gradient that fluctuates. Using long-term night light survey data, we examined seasonal patterns in alligators’ habitat use by size classes in midstream and downstream estuary zones of Shark River, Everglades National Park, in southern Florida. We observed predominantly large-sized alligators (total length ≥ 1.75 m); observations of alligators in the small size classes (0.5 m ≤ total length < 1.25 m) were rare especially in the higher-salinity downstream zone. The density of alligators in the downstream zone was lower than that of the midstream zone during the dry season when salinity increases due to reduced precipitation. Conversely, the density of the large size alligators was higher in the downstream zone than in the midstream zone during the wet season, likely because of reduced salinity. We also found a significant declining trend over time in the number of alligators in the dry season, which coincides with the reported decline in alligator relative density in southern Florida freshwater wetlands. Our results indicated high adaptability of alligators to the fluctuating habitat conditions. Use of estuaries by alligators is likely driven in part by physiology and possibly by reproductive cycle, and our results supported their opportunistic use of estuary habitat and ontogenetic niche shifts.

Look, Listen, Learn

ERIC Educational Resources Information Center

Pascopella, Angela

2011-01-01

Starting one's first job as a school superintendent can be daunting. The job has become even tougher now because new superintendents don't have the luxury of expanding successful programs or reducing class sizes given the struggling economy. A new superintendent coming on board has to be incredibly savvy and a communicator to survive long enough…

The CEIC Review, 2001. A Catalyst for Merging Research, Policy, and Practice.

ERIC Educational Resources Information Center

Hartman, Bonnie, Ed.; Rohland, Mark, Ed.

2001-01-01

These three volumes contain articles related to (1) improving educational productivity (lessons from economics); (2) school-to-work (STW); and (3) reduced class size, offering recommendations from national invitational conferences. Topics include making schools work; tax revolts and school performance; market pressure and the impact on…

Class Size: What Research Says and What It Means for State Policy

ERIC Educational Resources Information Center

Whitehurst, Grover J.; Chingos, Matthew M.

2011-01-01

Class size is one of the small number of variables in American K-12 education that are both thought to influence student learning and are subject to legislative action. Legislative mandates on maximum class size have been very popular at the state level. In recent decades, at least 24 states have mandated or incentivized class-size reduction…

Review of "Class Size: What Research Says and What It Means for State Policy"

ERIC Educational Resources Information Center

Whitmore Schanzenbach, Diane

2011-01-01

"Class Size: What Research Says and What It Means for State Policy" argues that increasing average class size by one student will save about 2% of total education spending with negligible impact on academic achievement. It justifies this conclusion on the basis that Class-Size Reduction (CSR) is not particularly effective and is not as…

Cellular metabolism and oxidative stress as a possible determinant for longevity in small breed and large breed dogs

PubMed Central

Winward, Josh; Beattie, Ursula; Cipolli, William

2018-01-01

Among species, larger animals tend to live longer than smaller ones, however, the opposite seems to be true for dogs—smaller dogs tend to live significantly longer than larger dogs across all breeds. We were interested in the mechanism that may allow for small breeds to age more slowly compared with large breeds in the context of cellular metabolism and oxidative stress. Primary dermal fibroblasts from small and large breed dogs were grown in culture. We measured basal oxygen consumption (OCR), proton leak, and glycolysis using a Seahorse XF96 oxygen flux analyzer. Additionally, we measured rates of reactive species (RS) production, reduced glutathione (GSH) content, mitochondrial content, lipid peroxidation (LPO) damage and DNA (8-OHdg) damage. Our data suggests that as dogs of both size classes age, proton leak is significantly higher in older dogs, regardless of size class. We found that all aspects of glycolysis were significantly higher in larger breeds compared with smaller breeds. We found significant differences between age classes in GSH concentration, and a negative correlation between DNA damage in puppies and mean breed lifespan. Interestingly, RS production showed no differences across size and age class. Thus, large breed dogs may have higher glycolytic rates, and DNA damage, suggesting a potential mechanism for their decreased lifespan compared with small breed dogs. PMID:29694441

Study design for the "effect of METOprolol in CARDioproteCtioN during an acute myocardial InfarCtion" (METOCARD-CNIC): a randomized, controlled parallel-group, observer-blinded clinical trial of early pre-reperfusion metoprolol administration in ST-segment elevation myocardial infarction.

PubMed

Ibanez, Borja; Fuster, Valentin; Macaya, Carlos; Sánchez-Brunete, Vicente; Pizarro, Gonzalo; López-Romero, Pedro; Mateos, Alonso; Jiménez-Borreguero, Jesús; Fernández-Ortiz, Antonio; Sanz, Ginés; Fernández-Friera, Leticia; Corral, Ervigio; Barreiro, Maria-Victoria; Ruiz-Mateos, Borja; Goicolea, Javier; Hernández-Antolín, Rosana; Acebal, Carlos; García-Rubira, Juan Carlos; Albarrán, Agustín; Zamorano, José Luis; Casado, Isabel; Valenciano, Juan; Fernández-Vázquez, Felipe; de la Torre, José María; Pérez de Prado, Armando; Iglesias-Vázquez, José Antonio; Martínez-Tenorio, Pedro; Iñiguez, Andrés

2012-10-01

Infarct size predicts post-infarction mortality. Oral β-blockade within 24 hours of a ST-segment elevation acute myocardial infarction (STEMI) is a class-IA indication, however early intravenous (IV) β-blockers initiation is not encouraged. In recent magnetic resonance imaging (MRI)-based experimental studies, the β(1)-blocker metoprolol has been shown to reduce infarct size only when administered before coronary reperfusion. To date, there is not a single trial comparing the pre- vs. post-reperfusion β-blocker initiation in STEMI. The METOCARD-CNIC trial is testing whether the early initiation of IV metoprolol before primary percutaneous coronary intervention (pPCI) could reduce infarct size and improve outcomes when compared to oral post-pPCI metoprolol initiation. The METOCARD-CNIC trial is a randomized parallel-group single-blind (to outcome evaluators) clinical effectiveness trial conducted in 5 Counties across Spain that will enroll 220 participants. Eligible are 18- to 80-year-old patients with anterior STEMI revascularized by pPCI ≤6 hours from symptom onset. Exclusion criteria are Killip-class ≥III, atrioventricular block or active treatment with β-blockers/bronchodilators. Primary end point is infarct size evaluated by MRI 5 to 7 days post-STEMI. Prespecified major secondary end points are salvage-index, left ventricular ejection fraction recovery (day 5-7 to 6 months), the composite of (death/malignant ventricular arrhythmias/reinfarction/admission due to heart failure), and myocardial perfusion. The METOCARD-CNIC trial is testing the hypothesis that the early initiation of IV metoprolol pre-reperfusion reduces infarct size in comparison to initiation of oral metoprolol post-reperfusion. Given the implications of infarct size reduction in STEMI, if positive, this trial might evidence that a refined use of an approved inexpensive drug can improve outcomes of patients with STEMI. Copyright © 2012 Mosby, Inc. All rights reserved.

Interference Fit Life Factors for Roller Bearings

NASA Technical Reports Server (NTRS)

Oswald, Fred B.; Zaretsky, Erwin V.; Poplawski, Joseph V.

2008-01-01

The effect of hoop stresses in reducing cylindrical roller bearing fatigue life was determined for various classes of inner ring interference fit. Calculations were performed for up to seven interference fit classes for each of ten bearing sizes. Each fit was taken at tightest, average and loosest values within the fit class for RBEC-5 tolerance, thus requiring 486 separate analyses. The hoop stresses were superimposed on the Hertzian principal stresses created by the applied radial load to calculate roller bearing fatigue life. The method was developed through a series of equations to calculate the life reduction for cylindrical roller bearings based on interference fit. All calculated lives are for zero initial bearing internal clearance. Any reduction in bearing clearance due to interference fit was compensated by increasing the initial (unmounted) clearance. Results are presented as tables and charts of life factors for bearings with light, moderate and heavy loads and interference fits ranging from extremely light to extremely heavy and for bearing accuracy class RBEC 5 (ISO class 5). Interference fits on the inner bearing ring of a cylindrical roller bearing can significantly reduce bearing fatigue life. In general, life factors are smaller (lower life) for bearings running under light load where the unfactored life is highest. The various bearing series within a particular bore size had almost identical interference fit life factors for a particular fit. The tightest fit at the high end of the RBEC-5 tolerance band defined in ANSI/ABMA shaft fit tables produces a life factor of approximately 0.40 for an inner-race maximum Hertz stress of 1200 MPa (175 ksi) and a life factor of 0.60 for an inner-race maximum Hertz stress of 2200 MPa (320 ksi). Interference fits also impact the maximum Hertz stress-life relation.

Epidemiology of school accidents during a six school-year period in one region in Poland.

PubMed

Sosnowska, Stefania; Kostka, Tomasz

2003-01-01

The aim of the study was to analyse the incidence of school accidents in relation to school size, urban/rural environment and conditions of physical education classes. 202 primary schools with nearly 50,000 students aged 7-15 years were studied during a 6-year period in the Włocławek region in Poland. There were in total 3274 school accidents per 293,000 student-years. Accidents during breaks (36.6%) and physical education (33.2%) were most common. Most frequently accidents took place at schoolyard (29.7%), gymnasium (20.2%), and in the corridor and stairs (25.2%). After adjustment for students' age and sex, student-staff ratio and duration of school hours, urban environment increased the probability of accident (OR: 1.25; 95% CI: 1.14-1.38). Middle-size schools (8-23 classes) had similar accident rate as small schools (OR: 0.93; 95% CI: 0.83-1.04), while schools with 24-32 classes (OR: 1.26; 95% CI: 1.10-1.43) and with > or = 33 classes (OR: 1.36; 95% CI: 1.17-1.58) had increased accident rate. Presence of a gymnasium was also associated with increased probability of accident (OR: 1.49; 95% CI: 1.38-1.61). Urban environment, larger school-size and equipment with full-size gymnasium are important and independent risk factors for school accidents. These findings provide some new insights into the epidemiology of school-related accidents and may be useful information for the planning of strategies to reduce accident incidence in schools.

Chiefs' Pocket Guide to Class Size: A Research Synthesis to Inform State Class Size Policies

ERIC Educational Resources Information Center

Council of Chief State School Officers, 2012

2012-01-01

Few questions in public education discourse benefit as much from research-based evidence as the question of class size--the pursuit of the ideal number of students that should be co-located for any particular period of instruction. But for policymakers, research on class size can be an embarrassment of riches, and much of the research appears to…

Percolation and epidemics in random clustered networks

NASA Astrophysics Data System (ADS)

Miller, Joel C.

2009-08-01

The social networks that infectious diseases spread along are typically clustered. Because of the close relation between percolation and epidemic spread, the behavior of percolation in such networks gives insight into infectious disease dynamics. A number of authors have studied percolation or epidemics in clustered networks, but the networks often contain preferential contacts in high degree nodes. We introduce a class of random clustered networks and a class of random unclustered networks with the same preferential mixing. Percolation in the clustered networks reduces the component sizes and increases the epidemic threshold compared to the unclustered networks.

Does Class Size Make a Difference?

ERIC Educational Resources Information Center

Glass, Gene V.; Down, A. Graham

1979-01-01

Argues that study findings indicate that lowered class size increases student achievement and improves school attitudes. Counter argument indicates there is little educational payoff and great monetary expense in small reductions in class size. (RH)

Ocean acidification reduces transfer of essential biomolecules in a natural plankton community

PubMed Central

Bermúdez, J. Rafael; Riebesell, Ulf; Larsen, Aud; Winder, Monika

2016-01-01

Ocean acidification (OA), a process of increasing seawater acidity caused by the uptake of anthropogenic carbon dioxide (CO2) by the ocean, is expected to change surface ocean pH to levels unprecedented for millions of years, affecting marine food web structures and trophic interactions. Using an in situ mesocosm approach we investigated effects of OA on community composition and trophic transfer of essential fatty acids (FA) in a natural plankton assemblage. Elevated pCO2 favored the smallest phytoplankton size class in terms of biomass, primarily picoeukaryotes, at the expense of chlorophyta and haptophyta in the nano-plankton size range. This shift in community composition and size structure was accompanied by a decline in the proportion of polyunsaturated FA (PUFA) to total FA content in the nano- and picophytoplankton size fractions. This decline was mirrored in a continuing reduction in the relative PUFA content of the dominant copepod, Calanus finmarchicus, which primarily fed on the nano-size class. Our results demonstrate that a shift in phytoplankton community composition and biochemical composition in response to rising CO2 can affect the transfer of essential compounds to higher trophic levels, which rely on their prey as a source for essential macromolecules. PMID:27324057

Incorporating "Virtual" and "Real World" Field Trips into Introductory Geography Modules

ERIC Educational Resources Information Center

Friess, Daniel A.; Oliver, Grahame J. H.; Quak, Michelle S. Y.; Lau, Annie Y. A.

2016-01-01

The "field trip" is a key pedagogical tool within geographical education to encourage deep learning, though they are increasingly difficult to implement due to reduced budgets, safety concerns and increasing class sizes. We incorporated three field-learning activities into a large introductory module. A traditional staff-led trip was the…

A Businessman's Guide to the Education Reform Debate. The Backgrounder No. 801.

ERIC Educational Resources Information Center

Allen, Jeanne; McLaughlin, Michael J.

Angered by the continued worsening of public school quality despite 1980s reform efforts and growing business-education partnerships, many American business leaders claim that money and concern are not enough. Boosting teacher salaries and reducing class size have yielded poor results. Business's general dismay with public school performance has…

Evaluating the Impact of National Educational Policy to Reduce Retention and Increase Achievement in Compulsory Education

ERIC Educational Resources Information Center

Barata, M. Clara; Calheiros, M. Manuela; Patrício, Joana Nunes; Graça, João; Lima, M. Luisa

2015-01-01

Despite the accumulated evidence that retention is an ineffective and potentially harmful remedial strategy, several countries struggle with high levels of retention in compulsory schooling. This article provides evidence of the impact of the Portuguese national educational policy "Programa Mais Sucesso Escolar" (PMSE) using class size,…

Case Study: Wallace-Rose Hill High School, Teachey, N.C.

ERIC Educational Resources Information Center

Southern Regional Education Board, Atlanta, GA.

In 1992, school leaders and teachers at Wallace-Rose High School in Teachey, North Carolina, began a multi-year whole-school improvement initiative that included the following actions: (1) identify low-performing students; (2) develop a team of faculty and administrators to work with low-performing students; (3) reduce class size for…

Teachers' Perceived Needs To Become More Effective Inclusion Practitioners: A Single School Study.

ERIC Educational Resources Information Center

King, Wendy; Edmunds, Alan

2001-01-01

Sixty-one teachers at a junior-senior high school in Nova Scotia responded to measures of inclusion attitudes and knowledge. Results revealed that teachers feel inadequately prepared for inclusion, need specific inclusion training, and feel that reducing workloads and class sizes would help. Significant positive correlations were found between…

Shifting to Active Learning: Assessment of a First-Year Biology Course in South Africa

ERIC Educational Resources Information Center

Downs, Colleen T.; Wilson, Amy-Leigh

2015-01-01

Large first-year class sizes have resulted in many lecturers adopting coping strategies consisting of direct-transmission mode teaching, reduced practical time, and assessment. Recently several strategies have been implemented in an attempt to improve student participation and active learning; however, these changes have to be facilitated and…

An Estimation of Technical Efficiency for Florida Public Elementary Schools

ERIC Educational Resources Information Center

Conroy, Stephen J.; Arguea, Nestor M.

2008-01-01

We use a frontier production function estimation technique to analyze whether elementary schools in Florida are operating at an efficient level and to explain any inefficiencies. A motivation for this analysis comes from recent state and federal level educational initiatives designed to improve school accountability and reduce class sizes. Results…

What does modern technology portend for uneven-aged southern pine silviculture?

Treesearch

Don C. Bragg; Michael G. Shelton; James M. Guldin; Ernest Lovett

2004-01-01

Recent changes in forest technology and market influences may impede the practice of uneven-aged (LEA) silviculture. For example, the use of tree-length systems with mechanized harvesters can unacceptably reduce the density of advanced regeneration, making it difficult to maintain the desired size class distribution. Changes to tree utilization standards, limited...

Population structure, density and food sources of Terebralia palustris (Potamididae: Gastropoda) in a low intertidal Avicennia marina mangrove stand (Inhaca Island, Mozambique)

NASA Astrophysics Data System (ADS)

Penha-Lopes, Gil; Bouillon, Steven; Mangion, Perrine; Macia, Adriano; Paula, José

2009-09-01

Population structure and distribution of Terebralia palustris were compared with the environmental parameters within microhabitats in a monospecific stand of Avicennia marina in southern Mozambique. Stable carbon and nitrogen isotope analyses of T. palustris and potential food sources (leaves, pneumatophore epiphytes, and surface sediments) were examined to establish the feeding preferences of T. palustris. Stable isotope signatures of individuals of different size classes and from different microhabitats were compared with local food sources. Samples of surface sediments 2.5-10 m apart showed some variation (-21.2‰ to -23.0‰) in δ13C, probably due to different contributions from seagrasses, microalgae and mangrove leaves, while δ15N values varied between 8.7‰ and 15.8‰, indicating that there is a very high variability within a small-scale microcosm. Stable isotope signatures differed significantly between the T. palustris size classes and between individuals of the same size class, collected in different microhabitats. Results also suggested that smaller individuals feed on sediment, selecting mainly benthic microalgae, while larger individuals feed on sediment, epiphytes and mangrove leaves. Correlations were found between environmental parameters and gastropod population structure and distribution vs. the feeding preferences of individuals of different size classes and in different microhabitats. While organic content and the abundance of leaves were parameters that correlated best with the total density of gastropods (>85%), the abundance of pneumatophores and leaves, as well as grain size, correlated better with the gastropod size distribution (>65%). Young individuals (height < 3 cm) occur predominantly in microhabitats characterized by a low density of leaf litter and pneumatophores, reduced organic matter and larger grain size, these being characteristic of lower intertidal open areas that favour benthic microalgal growth. With increasing shell height, T. palustris individuals start occupying microhabitats nearer the mangrove trees characterized by large densities of pneumatophores and litter, as well as sediments of smaller grain size, leading to higher organic matter availability in the sediment.

Development of shrinkage resistant microfibre-reinforced cement-based composites

NASA Astrophysics Data System (ADS)

Hamedanimojarrad, P.; Adam, G.; Ray, A. S.; Thomas, P. S.; Vessalas, K.

2012-06-01

Different shrinkage types may cause serious durability dilemma on restrained concrete parts due to crack formation and propagation. Several classes of fibres are used by concrete industry in order to reduce crack size and crack number. In previous studies, most of these fibre types were found to be effective in reducing the number and sizes of the cracks, but not in shrinkage strain reduction. This study deals with the influence of a newly introduced type of polyethylene fibre on drying shrinkage reduction. The novel fibre is a polyethylene microfibre in a new geometry, which is proved to reduce the amount of total shrinkage in mortars. This special hydrophobic polyethylene microfibre also reduces moisture loss of mortar samples. The experimental results on short and long-term drying shrinkage as well as on several other properties are reported. The hydrophobic polyethylene microfibre showed promising improvement in shrinkage reduction even at very low concentrations (0.1% of cement weight).

Beyond eruptive scenarios: assessing tephra fallout hazard from Neapolitan volcanoes.

PubMed

Sandri, Laura; Costa, Antonio; Selva, Jacopo; Tonini, Roberto; Macedonio, Giovanni; Folch, Arnau; Sulpizio, Roberto

2016-04-12

Assessment of volcanic hazards is necessary for risk mitigation. Typically, hazard assessment is based on one or a few, subjectively chosen representative eruptive scenarios, which use a specific combination of eruptive sizes and intensities to represent a particular size class of eruption. While such eruptive scenarios use a range of representative members to capture a range of eruptive sizes and intensities in order to reflect a wider size class, a scenario approach neglects to account for the intrinsic variability of volcanic eruptions, and implicitly assumes that inter-class size variability (i.e. size difference between different eruptive size classes) dominates over intra-class size variability (i.e. size difference within an eruptive size class), the latter of which is treated as negligible. So far, no quantitative study has been undertaken to verify such an assumption. Here, we adopt a novel Probabilistic Volcanic Hazard Analysis (PVHA) strategy, which accounts for intrinsic eruptive variabilities, to quantify the tephra fallout hazard in the Campania area. We compare the results of the new probabilistic approach with the classical scenario approach. The results allow for determining whether a simplified scenario approach can be considered valid, and for quantifying the bias which arises when full variability is not accounted for.

Summary of an Analysis of Pupil-Teacher Ratio and Class Size: Differences That Make a Difference and Its Implications on Staffing for Class-Size Reduction.

ERIC Educational Resources Information Center

Sharp, Mark A.

The purpose of this paper was to share findings from an earlier study and to provide a framework for administrators to use in the implementation of class-size reduction (CSR) in their buildings. The study examined actual and average class size (CS), pupil-teacher ratios (PTR), and their differences. A primary goal was to clarify the ramifications…

School Class Size: Research and Policy

ERIC Educational Resources Information Center

Glass, Gene V.; And Others

This book synthesizes research evidence to demonstrate that 1) class size is strongly related to pupil achievement; 2) smaller classes are more conducive to improved pupil performance than larger classes; 3) smaller classes provide more opportunities to adapt learning programs to individual needs; 4) pupils in smaller classes have more interest in…

Habitat degradation and fishing effects on the size structure of coral reef fish communities.

PubMed

Wilson, S K; Fisher, R; Pratchett, M S; Graham, N A J; Dulvy, N K; Turner, R A; Cakacaka, A; Polunin, N V C

2010-03-01

Overfishing and habitat degradation through climate change pose the greatest threats to sustainability of marine resources on coral reefs. We examined how changes in fishing pressure and benthic habitat composition influenced the size spectra of island-scale reef fish communities in Lau, Fiji. Between 2000 and 2006 fishing pressure declined in the Lau Islands due to declining human populations and reduced demand for fresh fish. At the same time, coral cover declined and fine-scale architectural complexity eroded due to coral bleaching and outbreaks of crown-of-thorns starfish, Acanthaster planci. We examined the size distribution of reef fish communities using size spectra analysis, the linearized relationship between abundance and body size class. Spatial variation in fishing pressure accounted for 31% of the variation in the slope of the size spectra in 2000, higher fishing pressure being associated with a steeper slope, which is indicative of fewer large-bodied fish and/or more small-bodied fish. Conversely, in 2006 spatial variation in habitat explained 53% of the variation in the size spectra slopes, and the relationship with fishing pressure was much weaker (approximately 12% of variation) than in 2000. Reduced cover of corals and lower structural complexity was associated with less steep size spectra slopes, primarily due to reduced abundance of fish < 20 cm. Habitat degradation will compound effects of fishing on coral reefs as increased fishing reduces large-bodied target species, while habitat loss results in fewer small-bodied juveniles and prey that replenish stocks and provide dietary resources for predatory target species. Effective management of reef resources therefore depends on both reducing fishing pressure and maintaining processes that encourage rapid recovery of coral habitat.

Effect of a fish stock's demographic structure on offspring survival and sensitivity to climate.

PubMed

Stige, Leif Christian; Yaragina, Natalia A; Langangen, Øystein; Bogstad, Bjarte; Stenseth, Nils Chr; Ottersen, Geir

2017-02-07

Commercial fishing generally removes large and old individuals from fish stocks, reducing mean age and age diversity among spawners. It is feared that these demographic changes lead to lower and more variable recruitment to the stocks. A key proposed pathway is that juvenation and reduced size distribution causes reduced ranges in spawning period, spawning location, and egg buoyancy; this is proposed to lead to reduced spatial distribution of fish eggs and larvae, more homogeneous ambient environmental conditions within each year-class, and reduced buffering against negative environmental influences. However, few, if any, studies have confirmed a causal link from spawning stock demographic structure through egg and larval distribution to year class strength at recruitment. We here show that high mean age and size in the spawning stock of Barents Sea cod (Gadus morhua) is positively associated with high abundance and wide spatiotemporal distribution of cod eggs. We find, however, no support for the hypothesis that a wide egg distribution leads to higher recruitment or a weaker recruitment-temperature correlation. These results are based on statistical analyses of a spatially resolved data set on cod eggs covering a period (1959-1993) with large changes in biomass and demographic structure of spawners. The analyses also account for significant effects of spawning stock biomass and a liver condition index on egg abundance and distribution. Our results suggest that the buffering effect of a geographically wide distribution of eggs and larvae on fish recruitment may be insignificant compared with other impacts.

Interference-Fit Life Factors for Roller Bearings

NASA Technical Reports Server (NTRS)

Oswald, Fred B.; Zaretsky, Erwin V.; Poplawski, Joseph V.

2009-01-01

The effect of hoop stresses in reducing cylindrical roller bearing fatigue life was determined for various classes of inner-ring interference fit. Calculations were performed for up to 7 fit classes for each of 10 bearing sizes. The hoop stresses were superimposed on the Hertzian principal stresses created by the applied radial load to calculate roller bearing fatigue life. A method was developed through a series of equations to calculate the life reduction for cylindrical roller bearings. All calculated lives are for zero initial internal clearance. Any reduction in bearing clearance due to interference fit would be compensated by increasing the initial (unmounted) clearance. Results are presented as tables and charts of life factors for bearings with light, moderate, and heavy loads and interference fits ranging from extremely light to extremely heavy for bearing accuracy class RBEC-5 (ISO class 5). Interference fits on the inner ring of a cylindrical roller bearing can significantly reduce bearing fatigue life. In general, life factors are smaller (lower life) for bearings running under light load where the unfactored life is highest. The various bearing series within a particular bore size had almost identical interference-fit life factors for a particular fit. The tightest fit at the high end of the tolerance band produces a life factor of approximately 0.40 for an inner-race maximum Hertz stress of 1200 MPa (175 ksi) and a life factor of 0.60 for an inner-race maximum Hertz stress of 2200 MPa (320 ksi). Interference fits also impact the maximum Hertz stress-life relation.

Class Size and Student Diversity: Two Sides of the Same Coin. Teacher Voice

ERIC Educational Resources Information Center

Froese-Germain, Bernie; Riel, Rick; McGahey, Bob

2012-01-01

Among Canadian teacher unions, discussions of class size are increasingly being informed by the importance of considering the diversity of student needs within the classroom (often referred to as class composition). For teachers, both class size and diversity matter. Teachers consistently adapt their teaching to address the individual needs of the…

Class Size Reduction: Implementation and Solutions.

ERIC Educational Resources Information Center

Krieger, Jean

This is a report of a study designed to discover the nature of interactions between teachers and students in regular-size classes (25 or more students) and small-size classes (fewer than 18 students). It also describes the efforts of one public school to maintain smaller classes. A review of the literature and observations of 11 primary classrooms…

Additional Evidence on the Relationship between Class Size and Student Performance

ERIC Educational Resources Information Center

Arias, J. J.; Walker, Douglas M.

2004-01-01

Much of the economic education literature suggests that the principles of economics class size does not significantly affect student performance. However, study methods have varied in terms of the aggregation level (student or class), the measure of performance (TUCE or course letter grade), and the class size measure (e.g., students who completed…

Hybrid Wing Body Configuration Scaling Study

NASA Technical Reports Server (NTRS)

Nickol, Craig L.

2012-01-01

The Hybrid Wing Body (HWB) configuration is a subsonic transport aircraft concept with the potential to simultaneously reduce fuel burn, noise and emissions compared to conventional concepts. Initial studies focused on very large applications with capacities for up to 800 passengers. More recent studies have focused on the large, twin-aisle class with passenger capacities in the 300-450 range. Efficiently scaling this concept down to the single aisle or smaller size is challenging due to geometric constraints, potentially reducing the desirability of this concept for applications in the 100-200 passenger capacity range or less. In order to quantify this scaling challenge, five advanced conventional (tube-and-wing layout) concepts were developed, along with equivalent (payload/range/technology) HWB concepts, and their fuel burn performance compared. The comparison showed that the HWB concepts have fuel burn advantages over advanced tube-and-wing concepts in the larger payload/range classes (roughly 767-sized and larger). Although noise performance was not quantified in this study, the HWB concept has distinct noise advantages over the conventional tube-and-wing configuration due to the inherent noise shielding features of the HWB. NASA s Environmentally Responsible Aviation (ERA) project will continue to investigate advanced configurations, such as the HWB, due to their potential to simultaneously reduce fuel burn, noise and emissions.

Class Size Effects on Student Achievement: Heterogeneity across Abilities and Fields

ERIC Educational Resources Information Center

De Paola, Maria; Ponzo, Michela; Scoppa, Vincenzo

2013-01-01

In this paper, we analyze class size effects on college students exploiting data from a project offering special remedial courses in mathematics and language skills to freshmen enrolled at an Italian medium-sized public university. To estimate the effects of class size, we exploit the fact that students and teachers are virtually randomly assigned…

Beyond eruptive scenarios: assessing tephra fallout hazard from Neapolitan volcanoes

PubMed Central

Sandri, Laura; Costa, Antonio; Selva, Jacopo; Tonini, Roberto; Macedonio, Giovanni; Folch, Arnau; Sulpizio, Roberto

2016-01-01

Assessment of volcanic hazards is necessary for risk mitigation. Typically, hazard assessment is based on one or a few, subjectively chosen representative eruptive scenarios, which use a specific combination of eruptive sizes and intensities to represent a particular size class of eruption. While such eruptive scenarios use a range of representative members to capture a range of eruptive sizes and intensities in order to reflect a wider size class, a scenario approach neglects to account for the intrinsic variability of volcanic eruptions, and implicitly assumes that inter-class size variability (i.e. size difference between different eruptive size classes) dominates over intra-class size variability (i.e. size difference within an eruptive size class), the latter of which is treated as negligible. So far, no quantitative study has been undertaken to verify such an assumption. Here, we adopt a novel Probabilistic Volcanic Hazard Analysis (PVHA) strategy, which accounts for intrinsic eruptive variabilities, to quantify the tephra fallout hazard in the Campania area. We compare the results of the new probabilistic approach with the classical scenario approach. The results allow for determining whether a simplified scenario approach can be considered valid, and for quantifying the bias which arises when full variability is not accounted for. PMID:27067389

Small Class Size and Its Effects.

ERIC Educational Resources Information Center

Biddle, Bruce J.; Berliner, David C.

2002-01-01

Describes several prominent early grades small-class-size projects and their effects on student achievement: Indiana's Project Prime Time, Tennessee's Project STAR (Student/Teacher Achievement Ratio), Wisconsin's SAGE (Student Achievement Guarantee in Education) Program, and the California class-size-reduction program. Lists several conclusions,…

A bill to amend title V of the Elementary and Secondary Education Act of 1965 to reduce class size through the use of highly qualified teachers, and for other purposes.

THOMAS, 111th Congress

Sen. Murray, Patty [D-WA

2009-12-16

Senate - 12/16/2009 Read twice and referred to the Committee on Health, Education, Labor, and Pensions. (All Actions) Tracker: This bill has the status IntroducedHere are the steps for Status of Legislation:

EFFECTS OF FOOD AVAILABILITY ON LIPID CLASS COMPOSITION AND C AND N ACCUMULATION IN HEPATOPANCREATIC, OVARIAN AND EMBRYONIC TISSUES OF THE GRASS SHRIMP PALAEMONETES PUGIO: A LABORATORY STUDY

EPA Science Inventory

In a laboratory experiment, limited food availability caused severe mortality and reduced growth of adult female grass shrimp Palaemonetes pugio. However, reproduction, measured by % gravid females and clutch size, was unaffected by food availability. It appears that female shrim...

Snag longevity in relation to wildfire and postfire salvage logging

Treesearch

Robin E. Russell; Victoria A. Saab; Jonathan G. Dudley; Jay J. Rotella

2006-01-01

Snags create nesting, foraging, and roosting habitat for a variety of wildlife species. Removal of snags through postfire salvage logging reduces the densities and size classes of snags remaining after wildfire. We determined important variables associated with annual persistence rates (the probability a snag remains standing from 1 year to the next) of large conifer...

Class Size.

ERIC Educational Resources Information Center

Ellis, Thomas I.

1985-01-01

After a brief introduction identifying current issues and trends in research on class size, this brochure reviews five recent studies bearing on the relationship of class size to educational effectiveness. Part 1 is a review of two interrelated and highly controversial "meta-analyses" or statistical integrations of research findings on…

Form and Objective of the Decision Rule in Absolute Identification

NASA Technical Reports Server (NTRS)

Balakrishnan, J. D.

1997-01-01

In several conditions of a line length identification experiment, the subjects' decision making strategies were systematically biased against the responses on the edges of the stimulus range. When the range and number of the stimuli were small, the bias caused the percentage of correct responses to be highest in the center and lowest on the extremes of the range. Two general classes of decision rules that would explain these results are considered. The first class assumes that subjects intend to adopt an optimal decision rule, but systematically misrepresent one or more parameters of the decision making context. The second class assumes that subjects use a different measure of performance than the one assumed by the experimenter: instead of maximizing the chances of a correct response, the subject attempts to minimize the expected size of the response error (a "fidelity criterion"). In a second experiment, extended experience and feedback did not diminish the bias effect, but explicitly penalizing all response errors equally, regardless of their size, did reduce or eliminate it in some subjects. Both results favor the fidelity criterion over the optimal rule.

Focus on California's Class-Size Reduction: Smaller Classes Aim To Launch Early Literacy.

ERIC Educational Resources Information Center

McRobbie, Joan

Smaller class sizes in California were viewed as a way to improve K-3 education, especially in the area of literacy. The urgency to act prompted state leaders to adopt class-size reduction (CSR) without knowing for sure that it would work and without establishing a formal procedure for evaluating the program. This report looks at past research on…

The Class Size Policy Debate. Working Paper No. 121.

ERIC Educational Resources Information Center

Krueger, Alan B.; Hanushek, Eric A.

These papers examine research on the impact of class size on student achievement. After an "Introduction," (Richard Rothstein), Part 1, "Understanding the Magnitude and Effect of Class Size on Student Achievement" (Alan B. Krueger), presents a reanalysis of Hanushek's 1997 literature review, criticizing Hanushek's vote-counting…

Significance of microhabitat heterogeneity in the spatial pattern and size-class structure of Anastatica hierochuntica L.

NASA Astrophysics Data System (ADS)

Hegazy, Ahmad K.; Kabiel, Hanan F.

2007-05-01

Anastatica hierochuntica L. (Brassicaceae) is a desert monocarpic annual species characterized by a topochory/ombrohydrochory type of seed dispersal. The hygrochastic nature of the dry skeletons (dead individuals) permits controlling seed dispersal by rain events. The amount of dispersed seeds is proportional to the intensity of rainfall. When light showers occur, seeds are released and remain in the site. Seeds dispersed in the vicinity of the mother or source plant (primary type of seed dispersal) resulted in clumped pattern and complicated interrelationships among size-classes of the population. Following heavy rainfall, most seeds are released and transported into small patches and shallow depressions which collect runoff water. The dead A. hierochuntica skeletons demonstrate site-dependent size-class structure, spatial pattern and spatial interrelationships in different microhabitats. Four microhabitat types have been sampled: runnels, patches and simple and compound depressions in two sites (gravel and sand). Ripley's K-function was used to analyze the spatial pattern in populations of A. hierochuntica skeletons in the study microhabitats. Clumped patterns were observed in nearly all of the study microhabitats. Populations of A. hierochuntica in the sand site were more productive than in the gravel site and usually had more individuals in the larger size-classes. In the compound-depression microhabitat, the degree of clumping decreased from the core zone to the intermediate zone then shifted into overdispersed pattern in the outer zone. At the within size-class level, the clumped pattern dominated in small size classes but shifted into random and overdispersed patterns in the larger size classes. Aggregation between small and large size-classes was not well-defined but large individuals were found closer to the smaller individuals than to those of their own class. In relation to the phytomass and the size-class structure, the outer zone of the simple depression and the outer and intermediate zones of the compound depression microhabitats were the most productive sites.

The Class Size Debate.

ERIC Educational Resources Information Center

Mishel, Lawrence, Ed.; Rothstein, Richard, Ed.

This collection of papers debates the merits of smaller class sizes and research methods used to evaluate the efficacy of this education reform measure. Four chapters focus on (1) "Understanding the Magnitude and Effect of Class Size on Student Achievement" (Alan B. Krueger), which discusses expenditures per student and economic criterion; (2)…

Researcher Perspectives on Class Size Reduction

ERIC Educational Resources Information Center

Graue, Elizabeth; Rauscher, Erica

2009-01-01

This article applies to class size research Grant and Graue's (1999) position that reviews of research represent conversations in the academic community. By extending our understanding of the class size reduction conversation beyond published literature to the perspectives of researchers who have studied the topic, we create a review that includes…

76 FR 59116 - Procurement List; Additions

Federal Register 2010, 2011, 2012, 2013, 2014

2011-09-23

... NSN: AF110--Shirt, Class A/Primary Duty, USAF, Men's, Long Sleeve, Dark Navy Blue, Numerous Sizes. NSN: AF111--Shirt, Class A/Primary Duty, USAF, Women's, Long Sleeve, Dark Navy Blue, Numerous Sizes. NSN: AF120--Shirt, Class A/Primary Duty, USAF, Men's, Short Sleeve, Dark Navy Blue, Numerous Sizes. NSN...

Compilation of Class Size Findings: Grade Level, School, and District.

ERIC Educational Resources Information Center

Miller-Whitehead, Marie

This study provides an overview of class size research, examples of various class size and pupil-teacher-ratio (PTR) configurations commonly used by practitioners, and the most recent findings of scientifically controlled experimental Tennessee STAR studies. The learning environment is hierarchical in nature, with student-level data influenced by…

The Opportunity Cost of Smaller Classes: A State-By-State Spending Analysis. Schools in Crisis: Making Ends Meet

ERIC Educational Resources Information Center

Roza, Marguerite; Ouijdani, Monica

2012-01-01

Two seemingly different threads are in play on the issue of class size. The first is manifested in media reports that tell readers that class sizes are rising to concerning levels. The second thread appears in the work of some researchers and education leaders and suggests that repurposing class-size reduction funds to pay for other reforms may…

[Nitrogen Fraction Distributions and Impacts on Soil Nitrogen Mineralization in Different Vegetation Restorations of Karst Rocky Desertification].

PubMed

Hu, Ning; Ma, Zhi-min; Lan, Jia-cheng; Wu, Yu-chun; Chen, Gao-qi; Fu, Wa-li; Wen, Zhi-lin; Wang, Wen-jing

2015-09-01

In order to illuminate the impact on soil nitrogen accumulation and supply in karst rocky desertification area, the distribution characteristics of soil nitrogen pool for each class of soil aggregates and the relationship between aggregates nitrogen pool and soil nitrogen mineralization were analyzed in this study. The results showed that the content of total nitrogen, light fraction nitrogen, available nitrogen and mineral nitrogen in soil aggregates had an increasing tendency along with the descending of aggregate-size, and the highest content was occurred in < 0. 25 mm. The content of nitrogen fractions for all aggregate-classes followed in the order of abandoned land < grass land < brush land < brush-arbor land < arbor land in different sample plots. Artificial forest lands had more effects on the improvement of the soil nitrogen than honeysuckle land. In this study it also showed the nitrogen stockpiling quantity of each aggregate-size class was differed in all aggregate-size classes, in which the content of nitrogen fraction in 5-10 mm and 2-5 mm classes of soil aggregate-size were the highest. And it meant that soil nutrient mainly was stored in large size aggregates. Large size aggregates were significant to the storage of soil nutrient. For each class of soil aggregate-size, the contribution of the nitrogen stockpiling quantity of 0. 25-1 mm class to soil net nitrogen mineralization quantity was the biggest, and following >5mm and 2-5 mm classes, and the others were the smallest. With the positive vegetation succession, the weight percentage of > 5 mm aggregate-size classes was improved and the nitrogen storage of macro-aggregates also was increased. Accordingly, the capacity of soil supply mineral nitrogen and storage organic nitrogen were intensified.

Solid-state 13C NMR experiments reveal effects of aggregate size on the chemical composition of particulate organic matter in grazed steppe soils

NASA Astrophysics Data System (ADS)

Steffens, M.; Kölbl, A.; Kögel-Knabner, I.

2009-04-01

Grazing is one of the most important factors that may reduce soil organic matter (SOM) stocks and subsequently deteriorate aggregate stability in grassland topsoils. Land use management and grazing reduction are assumed to increase the input of OM, improve the soil aggregation and change species composition of vegetation (changes depth of OM input). Many studies have evaluated the impact of grazing cessation on SOM quantity. But until today little is known about the impact of grazing cessation on the chemical quality of SOM in density fractions, aggregate size classes and different horizons. The central aim of this study was to analyse the quality of SOM fractions in differently sized aggregates and horizons as affected by increased inputs of organic matter due to grazing exclusion. We applied a combined aggregate size, density and particle size fractionation procedure to sandy steppe topsoils with different organic matter inputs due to different grazing intensities (continuously grazed = Cg, winter grazing = Wg, ungrazed since 1999 = Ug99, ungrazed since 1979 = Ug79). Three different particulate organic matter (POM; free POM, in aggregate occluded POM and small in aggregate occluded POM) and seven mineral-associated organic matter fractions were separated for each of three aggregate size classes (coarse = 2000-6300 m, medium = 630-2000 m and fine =

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eilert, P.L.; Hoeschele, M.

This paper discussed a market-transformation program to reduce energy use in modular school classrooms, a large part of new construction activities in California's schools. Today's modular classrooms cost more to operate than is necessary to provide effective, comfortable learning conditions for students and teachers. Although past resource acquisition programs have created a demand for efficient products and services, modular classrooms remain poorly differentiated in this respect. The cost-effectiveness of a range of potential energy efficiency measures (EEM's) were evaluated including lighting, alternative HVAC options, and improved envelope features. Viable EEM's were combined in two separate packages. The first includes measuresmore » that can easily be implemented and are projected to reduce operating costs by 30%. The second implements a daylighting system, a two-stage evaporative cooler, and radiant heating, resulting in projected annual energy cost savings over 60%. Transforming the market for modular classrooms is accomplished using natural market forces, rather than financial incentives directed at an entire industry. Proactive efforts are focused on the manufacturing industry's change leaders to commercialize energy-efficient products. Lost market share and peer pressure do the heavy lifting of convincing market followers to upgrade their products. Demand for efficient classrooms is increased by educating schools about the new products' financial advantages, comfort enhancements, and environmental benefits. As new products become established in the marketplace, support will be gradually withdrawn. The relevance of this work extends beyond California, given other States' programs to reduce class size, and the Presidents initiative to reduce class size nationally.« less

Imidazopyridazine Inhibitors of Plasmodium falciparum Calcium-Dependent Protein Kinase 1 Also Target Cyclic GMP-Dependent Protein Kinase and Heat Shock Protein 90 To Kill the Parasite at Different Stages of Intracellular Development

PubMed Central

Moon, Robert W.; Whalley, David; Bowyer, Paul W.; Wallace, Claire; Rochani, Ankit; Nageshan, Rishi K.; Howell, Steven A.; Grainger, Munira; Jones, Hayley M.; Ansell, Keith H.; Chapman, Timothy M.; Taylor, Debra L.; Osborne, Simon A.; Baker, David A.; Tatu, Utpal

2015-01-01

Imidazopyridazine compounds are potent, ATP-competitive inhibitors of calcium-dependent protein kinase 1 (CDPK1) and of Plasmodium falciparum parasite growth in vitro. Here, we show that these compounds can be divided into two classes depending on the nature of the aromatic linker between the core and the R2 substituent group. Class 1 compounds have a pyrimidine linker and inhibit parasite growth at late schizogony, whereas class 2 compounds have a nonpyrimidine linker and inhibit growth in the trophozoite stage, indicating different modes of action for the two classes. The compounds also inhibited cyclic GMP (cGMP)-dependent protein kinase (PKG), and their potency against this enzyme was greatly reduced by substitution of the enzyme's gatekeeper residue at the ATP binding site. The effectiveness of the class 1 compounds against a parasite line expressing the modified PKG was also substantially reduced, suggesting that these compounds kill the parasite primarily through inhibition of PKG rather than CDPK1. HSP90 was identified as a binding partner of class 2 compounds, and a representative compound bound to the ATP binding site in the N-terminal domain of HSP90. Reducing the size of the gatekeeper residue of CDPK1 enabled inhibition of the enzyme by bumped kinase inhibitors; however, a parasite line expressing the modified enzyme showed no change in sensitivity to these compounds. Taken together, these findings suggest that CDPK1 may not be a suitable target for further inhibitor development and that the primary mechanism through which the imidazopyridazines kill parasites is by inhibition of PKG or HSP90. PMID:26711771

Imidazopyridazine Inhibitors of Plasmodium falciparum Calcium-Dependent Protein Kinase 1 Also Target Cyclic GMP-Dependent Protein Kinase and Heat Shock Protein 90 To Kill the Parasite at Different Stages of Intracellular Development.

PubMed

Green, Judith L; Moon, Robert W; Whalley, David; Bowyer, Paul W; Wallace, Claire; Rochani, Ankit; Nageshan, Rishi K; Howell, Steven A; Grainger, Munira; Jones, Hayley M; Ansell, Keith H; Chapman, Timothy M; Taylor, Debra L; Osborne, Simon A; Baker, David A; Tatu, Utpal; Holder, Anthony A

2015-12-28

Imidazopyridazine compounds are potent, ATP-competitive inhibitors of calcium-dependent protein kinase 1 (CDPK1) and of Plasmodium falciparum parasite growth in vitro. Here, we show that these compounds can be divided into two classes depending on the nature of the aromatic linker between the core and the R2 substituent group. Class 1 compounds have a pyrimidine linker and inhibit parasite growth at late schizogony, whereas class 2 compounds have a nonpyrimidine linker and inhibit growth in the trophozoite stage, indicating different modes of action for the two classes. The compounds also inhibited cyclic GMP (cGMP)-dependent protein kinase (PKG), and their potency against this enzyme was greatly reduced by substitution of the enzyme's gatekeeper residue at the ATP binding site. The effectiveness of the class 1 compounds against a parasite line expressing the modified PKG was also substantially reduced, suggesting that these compounds kill the parasite primarily through inhibition of PKG rather than CDPK1. HSP90 was identified as a binding partner of class 2 compounds, and a representative compound bound to the ATP binding site in the N-terminal domain of HSP90. Reducing the size of the gatekeeper residue of CDPK1 enabled inhibition of the enzyme by bumped kinase inhibitors; however, a parasite line expressing the modified enzyme showed no change in sensitivity to these compounds. Taken together, these findings suggest that CDPK1 may not be a suitable target for further inhibitor development and that the primary mechanism through which the imidazopyridazines kill parasites is by inhibition of PKG or HSP90. Copyright © 2016 Green et al.

Effect of a fish stock's demographic structure on offspring survival and sensitivity to climate

PubMed Central

Stige, Leif Christian; Yaragina, Natalia A.; Langangen, Øystein; Bogstad, Bjarte; Stenseth, Nils Chr.; Ottersen, Geir

2017-01-01

Commercial fishing generally removes large and old individuals from fish stocks, reducing mean age and age diversity among spawners. It is feared that these demographic changes lead to lower and more variable recruitment to the stocks. A key proposed pathway is that juvenation and reduced size distribution causes reduced ranges in spawning period, spawning location, and egg buoyancy; this is proposed to lead to reduced spatial distribution of fish eggs and larvae, more homogeneous ambient environmental conditions within each year-class, and reduced buffering against negative environmental influences. However, few, if any, studies have confirmed a causal link from spawning stock demographic structure through egg and larval distribution to year class strength at recruitment. We here show that high mean age and size in the spawning stock of Barents Sea cod (Gadus morhua) is positively associated with high abundance and wide spatiotemporal distribution of cod eggs. We find, however, no support for the hypothesis that a wide egg distribution leads to higher recruitment or a weaker recruitment–temperature correlation. These results are based on statistical analyses of a spatially resolved data set on cod eggs covering a period (1959−1993) with large changes in biomass and demographic structure of spawners. The analyses also account for significant effects of spawning stock biomass and a liver condition index on egg abundance and distribution. Our results suggest that the buffering effect of a geographically wide distribution of eggs and larvae on fish recruitment may be insignificant compared with other impacts. PMID:28115694

Teachers' Beliefs on the Relative Effectiveness of Reforms for Motivating Pupils and Alleviating Behavior Problems

ERIC Educational Resources Information Center

Burns, Robert B.

1977-01-01

A survey of 231 British teachers assessed their ratings of classroom reforms which might stimulate student interest and reduce behavior problems. Results correlate with those from a study in 1952, showing abolition of corporal punishment as having little effect and smaller class size, remedial courses, and parental support as being most effective.…

Low Voltage Low Light Imager and Photodetector

NASA Technical Reports Server (NTRS)

Nikzad, Shouleh (Inventor); Martin, Chris (Inventor); Hoenk, Michael E. (Inventor)

2013-01-01

Highly efficient, low energy, low light level imagers and photodetectors are provided. In particular, a novel class of Della-Doped Electron Bombarded Array (DDEBA) photodetectors that will reduce the size, mass, power, complexity, and cost of conventional imaging systems while improving performance by using a thinned imager that is capable of detecting low-energy electrons, has high gain, and is of low noise.

A Meta-Analysis of Class Sizes and Ratios in Early Childhood Education Programs: Are Thresholds of Quality Associated with Greater Impacts on Cognitive, Achievement, and Socioemotional Outcomes?

ERIC Educational Resources Information Center

Bowne, Jocelyn Bonnes; Magnuson, Katherine A.; Schindler, Holly S.; Duncan, Greg J.; Yoshikawa, Hirokazu

2017-01-01

This study uses data from a comprehensive database of U.S. early childhood education program evaluations published between 1960 and 2007 to evaluate the relationship between class size, child-teacher ratio, and program effect sizes for cognitive, achievement, and socioemotional outcomes. Both class size and child-teacher ratio showed nonlinear…

Class Size: A Battle between Accountability and Quality Instruction

ERIC Educational Resources Information Center

Januszka, Cynthia; Dixon-Krauss, Lisbeth

2008-01-01

A substantial amount of controversy surrounds the issue of class size in public schools. Parents and teachers are on one side, touting the benefits of smaller class sizes (e.g., increased academic achievement, greater student-teacher interaction, utilization of more innovative teaching strategies, and a decrease in discipline problems). On the…

Class Size and Academic Achievement in Introductory Political Science Courses

ERIC Educational Resources Information Center

Towner, Terri L.

2016-01-01

Research on the influence of class size on student academic achievement is important for university instructors, administrators, and students. The article examines the influence of class size--a small section versus a large section--in introductory political science courses on student grades in two comparable semesters. It is expected that…

Class Size Revisited: Glass and Smith in Perspective.

ERIC Educational Resources Information Center

Hess, Fritz

Gene V. Glass and Mary Lee Smith claim in their report, "Meta-Analysis of Research on the Relationship of Class-Size and Achievement" (ED 168 129), that their integration of data from 80 previous studies through complex regression analysis techniques revealed a "clear and strong relationship" between decreases in class size and increases in…

The Effects of Videoconferencing, Class Size, and Learner Characteristics on Training Outcomes

ERIC Educational Resources Information Center

Brown, Kenneth G.; Rietz, Thomas A.; Sugrue, Brenda

2005-01-01

We examined direct and interaction effects of learners' characteristics (cognitive ability, prior knowledge, prior experience, and motivation to learn) and classroom characteristics (videoconferencing and class size) on learning from a 16-week course. A 2x2 quasi-experimental design varied the class size between large (approximately 60 students)…

Effects of Class Size and Attendance Policy on University Classroom Interaction in Taiwan

ERIC Educational Resources Information Center

Bai, Yin; Chang, Te-Sheng

2016-01-01

Classroom interaction experience is one of the main parts of students' learning lives. However, surprisingly little research has investigated students' perceptions of classroom interaction with different attendance policies across different class sizes in the higher education system. To elucidate the effects of class size and attendance policy on…

Biomass and productivity of three phytoplankton size classes in San Francisco Bay.

USGS Publications Warehouse

Cole, B.E.; Cloern, J.E.; Alpine, A.E.

1986-01-01

The 5-22 mu m size accounted for 40-50% of annual production in each embayment, but production by phytoplanton >22 mu m ranged from 26% in the S reach to 54% of total phytoplankton production in the landward embayment of the N reach. A productivity index is derived that predicts daily productivity for each size class as a function of ambient irradiance and integrated chlorophyll a in the photic zone. For the whole phytoplankton community and for each size class, this index was constant at approx= 0.76 g C m-2 (g chlorophyll a Einstein)-1. The annual means of maximum carbon assimilation numbers were usually similar for the three size classes. Spatial and temporal variations in size-fractionated productivity are primarily due to differences in biomass rather than size-dependent carbon assimilation rates. -from Authors

Exploring the full natural variability of eruption sizes within probabilistic hazard assessment of tephra dispersal

NASA Astrophysics Data System (ADS)

Selva, Jacopo; Sandri, Laura; Costa, Antonio; Tonini, Roberto; Folch, Arnau; Macedonio, Giovanni

2014-05-01

The intrinsic uncertainty and variability associated to the size of next eruption strongly affects short to long-term tephra hazard assessment. Often, emergency plans are established accounting for the effects of one or a few representative scenarios (meant as a specific combination of eruptive size and vent position), selected with subjective criteria. On the other hand, probabilistic hazard assessments (PHA) consistently explore the natural variability of such scenarios. PHA for tephra dispersal needs the definition of eruptive scenarios (usually by grouping possible eruption sizes and vent positions in classes) with associated probabilities, a meteorological dataset covering a representative time period, and a tephra dispersal model. PHA results from combining simulations considering different volcanological and meteorological conditions through a weight given by their specific probability of occurrence. However, volcanological parameters, such as erupted mass, eruption column height and duration, bulk granulometry, fraction of aggregates, typically encompass a wide range of values. Because of such a variability, single representative scenarios or size classes cannot be adequately defined using single values for the volcanological inputs. Here we propose a method that accounts for this within-size-class variability in the framework of Event Trees. The variability of each parameter is modeled with specific Probability Density Functions, and meteorological and volcanological inputs are chosen by using a stratified sampling method. This procedure allows avoiding the bias introduced by selecting single representative scenarios and thus neglecting most of the intrinsic eruptive variability. When considering within-size-class variability, attention must be paid to appropriately weight events falling within the same size class. While a uniform weight to all the events belonging to a size class is the most straightforward idea, this implies a strong dependence on the thresholds dividing classes: under this choice, the largest event of a size class has a much larger weight than the smallest event of the subsequent size class. In order to overcome this problem, in this study, we propose an innovative solution able to smoothly link the weight variability within each size class to the variability among the size classes through a common power law, and, simultaneously, respect the probability of different size classes conditional to the occurrence of an eruption. Embedding this procedure into the Bayesian Event Tree scheme enables for tephra fall PHA, quantified through hazard curves and maps representing readable results applicable in planning risk mitigation actions, and for the quantification of its epistemic uncertainties. As examples, we analyze long-term tephra fall PHA at Vesuvius and Campi Flegrei. We integrate two tephra dispersal models (the analytical HAZMAP and the numerical FALL3D) into BET_VH. The ECMWF reanalysis dataset are used for exploring different meteorological conditions. The results obtained clearly show that PHA accounting for the whole natural variability significantly differs from that based on a representative scenarios, as in volcanic hazard common practice.

Polymorphic mountain whitefish (Prosopium williamsoni) in a coastal riverscape: size class assemblages, distribution, and habitat associations

USGS Publications Warehouse

Starr, James C.; Torgersen, Christian E.

2015-01-01

We compared the assemblage structure, spatial distributions, and habitat associations of mountain whitefish (Prosopium williamsoni) morphotypes and size classes. We hypothesised that morphotypes would have different spatial distributions and would be associated with different habitat features based on feeding behaviour and diet. Spatially continuous sampling was conducted over a broad extent (29 km) in the Calawah River, WA (USA). Whitefish were enumerated via snorkelling in three size classes: small (10–29 cm), medium (30–49 cm), and large (≥50 cm). We identified morphotypes based on head and snout morphology: a pinocchio form that had an elongated snout and a normal form with a blunted snout. Large size classes of both morphotypes were distributed downstream of small and medium size classes, and normal whitefish were distributed downstream of pinocchio whitefish. Ordination of whitefish assemblages with nonmetric multidimensional scaling revealed that normal whitefish size classes were associated with higher gradient and depth, whereas pinocchio whitefish size classes were positively associated with pool area, distance upstream, and depth. Reach-scale generalised additive models indicated that normal whitefish relative density was associated with larger substrate size in downstream reaches (R2 = 0.64), and pinocchio whitefish were associated with greater stream depth in the reaches farther upstream (R2 = 0.87). These results suggest broad-scale spatial segregation (1–10 km), particularly between larger and more phenotypically extreme individuals. These results provide the first perspective on spatial distributions and habitat relationships of polymorphic mountain whitefish.

Global warming benefits the small in aquatic ecosystems.

PubMed

Daufresne, Martin; Lengfellner, Kathrin; Sommer, Ulrich

2009-08-04

Understanding the ecological impacts of climate change is a crucial challenge of the twenty-first century. There is a clear lack of general rules regarding the impacts of global warming on biota. Here, we present a metaanalysis of the effect of climate change on body size of ectothermic aquatic organisms (bacteria, phyto- and zooplankton, and fish) from the community to the individual level. Using long-term surveys, experimental data and published results, we show a significant increase in the proportion of small-sized species and young age classes and a decrease in size-at-age. These results are in accordance with the ecological rules dealing with the temperature-size relationships (i.e., Bergmann's rule, James' rule and Temperature-Size Rule). Our study provides evidence that reduced body size is the third universal ecological response to global warming in aquatic systems besides the shift of species ranges toward higher altitudes and latitudes and the seasonal shifts in life cycle events.

What We Have Learned about Class Size Reduction in California. Capstone Report.

ERIC Educational Resources Information Center

Bohrnstedt, George W., Ed.; Stecher, Brian M., Ed.

This final report on the California Class Size Reduction (CSR) initiative summarizes findings from three earlier reports dating back to 1997. Chapter 1 recaps the history of California's CSR initiative and includes a discussion of what state leaders' expectations were when CSR was passed. The chapter also describes research on class-size reduction…

Teacher/Student Interactions in Public Elementary Schools When Class Size is a Factor.

ERIC Educational Resources Information Center

Krieger, Jean D.

This report describes a study designed to discover the nature of teacher-student interactions in regular-size classes with 25 or more students and small-size classes with fewer than 18 students. Eleven public-school primary classrooms were observed, and the interactions between the teachers and students were studied. Verbal and nonverbal…

Serendipitous Policy Implications from Class-Size-Initiated Inquiry: IAQ?

ERIC Educational Resources Information Center

Achilles, C. M.; Prout, Jean; Finn, J. D.; Bobbett, Gordon C.

The level of carbon dioxide in a classroom can have a significant negative effect on teaching and learning. Carbon dioxide (CO2) level is affected by class size and time of day. Six urban schools were studied to characterize the effects of these three factors on different class sizes. Carbon monoxide, CO2, temperature, and relative humidity…

The Cost of Class Size Reduction: Advice for Policymakers. RAND Graduate School Dissertation.

ERIC Educational Resources Information Center

Reichardt, Robert E.

This dissertation provides information to state-level policymakers that will help them avoid two implementation problems seen in the past in California's class-size-reduction (CSR) reform. The first problem was that flat, per student reimbursement did not adequately cover costs in districts with larger pre-CSR class-sizes or smaller schools. The…

Size Matters. The Relevance and Hicksian Surplus of Preferred College Class Size

ERIC Educational Resources Information Center

Mandel, Philipp; Susmuth, Bernd

2011-01-01

The contribution of this paper is twofold. First, we examine the impact of class size on student evaluations of instructor performance using a sample of approximately 1400 economics classes held at the University of Munich from Fall 1998 to Summer 2007. We offer confirmatory evidence for the recent finding of a large, highly significant, and…

Class Size Effects on Reading Achievement Using PIRLS Data: Evidence from Greece

ERIC Educational Resources Information Center

Konstantopoulos, Spyros; Traynor, Anne

2014-01-01

Background/Context: The effects of class size on student achievement have gained considerable attention in education research and policy, especially over the last 30 years. Perhaps the best evidence about the effects of class size thus far has been produced from analyses of Project STAR data, a large-scale experiment where students and teachers…

The Effects of Class Size on Student Achievement in Intermediate Level Elementary Students

ERIC Educational Resources Information Center

McInerney, Melissa

2014-01-01

Class size and student achievement have been debated for decades. The vast amount of research on this topic is either conflicting or inconclusive. There are large and small scale studies that support both sides of this dilemma (Achilles, Nye, Boyd-Zaharias, Fulton, & Cain, 1994; Glass & Smith, 1979; Slavin, 1989). Class size reduction is a…

Class Size and Language Learning in Hong Kong: The Students' Perspective

ERIC Educational Resources Information Center

Harfitt, Gary James

2012-01-01

Background: There is currently ongoing debate in Hong Kong between the teachers' union and the Government on the reduction of large class size (typically more than 40 students) in secondary schools and whether smaller class sizes might facilitate improvements in teaching and learning. In fact, many Hong Kong secondary schools have already started…

Does Class Size in First Grade Relate to Children's Academic and Social Performance or Observed Classroom Processes?

ERIC Educational Resources Information Center

Allhusen, Virginia; Belsky, Jay; Booth-LaForce, Cathryn L.; Bradley, Robert; Brownwell, Celia A; Burchinal, Margaret; Campbell, Susan B.; Clarke-Stewart, K. Alison; Cox, Martha; Friedman, Sarah L.; Hirsh-Pasek, Kathryn; Houts, Renate M.; Huston, Aletha; Jaeger, Elizabeth; Johnson, Deborah J.; Kelly, Jean F.; Knoke, Bonnie; Marshall, Nancy; McCartney, Kathleen; Morrison, Frederick J.; O'Brien, Marion; Tresch Owen, Margaret; Payne, Chris; Phillips, Deborah; Pianta, Robert; Randolph, Suzanne M.; Robeson, Wendy W.; Spieker, Susan; Lowe Vandell, Deborah; Weinraub, Marsha

2004-01-01

This study evaluated the extent to which first-grade class size predicted child outcomes and observed classroom processes for 651 children (in separate classrooms). Analyses examined observed child-adult ratios and teacher-reported class sizes. Smaller classrooms showed higher quality instructional and emotional support, although children were…

Class Size and Student Evaluations in Sweden

ERIC Educational Resources Information Center

Westerlund, Joakim

2008-01-01

This paper examines the effect of class size on student evaluations of the quality of an introductory mathematics course at Lund University in Sweden. In contrast to much other studies, we find a large negative, and statistically significant, effect of class size on the quality of the course. This result appears to be quite robust, as almost all…

A hierarchical word-merging algorithm with class separability measure.

PubMed

Wang, Lei; Zhou, Luping; Shen, Chunhua; Liu, Lingqiao; Liu, Huan

2014-03-01

In image recognition with the bag-of-features model, a small-sized visual codebook is usually preferred to obtain a low-dimensional histogram representation and high computational efficiency. Such a visual codebook has to be discriminative enough to achieve excellent recognition performance. To create a compact and discriminative codebook, in this paper we propose to merge the visual words in a large-sized initial codebook by maximally preserving class separability. We first show that this results in a difficult optimization problem. To deal with this situation, we devise a suboptimal but very efficient hierarchical word-merging algorithm, which optimally merges two words at each level of the hierarchy. By exploiting the characteristics of the class separability measure and designing a novel indexing structure, the proposed algorithm can hierarchically merge 10,000 visual words down to two words in merely 90 seconds. Also, to show the properties of the proposed algorithm and reveal its advantages, we conduct detailed theoretical analysis to compare it with another hierarchical word-merging algorithm that maximally preserves mutual information, obtaining interesting findings. Experimental studies are conducted to verify the effectiveness of the proposed algorithm on multiple benchmark data sets. As shown, it can efficiently produce more compact and discriminative codebooks than the state-of-the-art hierarchical word-merging algorithms, especially when the size of the codebook is significantly reduced.

The Effects of Class Size in Online College Courses: Experimental Evidence. CEPA Working Paper No. 15-14

ERIC Educational Resources Information Center

Bettinger, Eric; Doss, Christopher; Loeb, Susanna; Taylor, Eric

2015-01-01

Class size is a first-order consideration in the study of education production and education costs. How larger or smaller classes affect student outcomes is especially relevant to the growth and design of online classes. We study a field experiment in which college students were quasi-randomly assigned to either a large or a small class. All…

45 CFR 1306.32 - Center-based program option.

Code of Federal Regulations, 2011 CFR

2011-10-01

... Center-based program option. (a) Class size. (1) Head Start classes must be staffed by a teacher and an aide or two teachers and, whenever possible, a volunteer. (2) Grantees must determine their class size based on the predominant age of the children who will participate in the class and whether or not a...

Modified centroid for estimating sand, silt, and clay from soil texture class

USDA-ARS?s Scientific Manuscript database

Models that require inputs of soil particle size commonly use soil texture class for input; however, texture classes do not represent the continuum of soil size fractions. Soil texture class and clay percentage are collected as a standard practice for many land management agencies (e.g., NRCS, BLM, ...

Special Education Program Standards Study. Commonwealth of Virginia. Final Technical Report.

ERIC Educational Resources Information Center

Keith, Timothy Z.; And Others

This federally funded study investigated Virginia special education program standards, focusing on local applications of the standards for class size and class mix and the effect of varying class size and class mix on student outcomes. The study concentrated on students with educable mental retardation, severe emotional disturbance, and specific…

The False Promise of Class-Size Reduction

ERIC Educational Resources Information Center

Chingos, Matthew M.

2011-01-01

Class-size reduction, or CSR, is enormously popular with parents, teachers, and the public in general. Many parents believe that their children will benefit from more individualized attention in a smaller class and many teachers find smaller classes easier to manage. The pupil-teacher ratio is an easy statistic for the public to monitor as a…

Two classes of anti-platelet drugs reduce anatomical infarct size in monkey hearts.

PubMed

Yang, Xi-Ming; Liu, Yanping; Cui, Lin; Yang, Xiulan; Liu, Yongge; Tandon, Narendra; Kambayashi, Junichi; Downey, James M; Cohen, Michael V

2013-04-01

Recent studies in rabbits have demonstrated that platelet P2Y12 receptor antagonists are cardioprotective, and that the mechanism is surprisingly not related to blockade of platelet aggregation but rather to triggering of the same signal transduction pathway seen in pre- and postconditioning. We wanted to determine whether this same cardioprotection could be documented in a primate model and whether the protection was limited to P2Y12 receptor antagonists or was a class effect. Thirty-one macaque monkeys underwent 90-min LAD occlusion/4-h reperfusion. The platelet P2Y12 receptor blocker cangrelor started just prior to reperfusion significantly decreased infarction by an amount equivalent to that seen with ischemic postconditioning (p < 0.001). For any size of risk zone, infarct size in treated hearts was significantly smaller than that in control hearts. OM2, an investigational murine antibody against the primate collagen receptor glycoprotein (GP) VI, produced similar protection (p < 0.01) suggesting a class effect. Both cangrelor and OM2 were quite effective at blocking platelet aggregation (94 % and 97 %, respectively). Thus in a primate model in which infarct size could be determined directly platelet anti-aggregatory agents are cardioprotective. The important implication of these investigations is that patients with acute myocardial infarction who are treated with platelet anti-aggregatory agents prior to revascularization may already be in a postconditioned state. This hypothesis may explain why in recent clinical trials postconditioning-mimetic interventions which were so protective in animal models had at best only a modest effect.

46 CFR 56.30-10 - Flanged joints (modifies 104.5.1(a)).

Code of Federal Regulations, 2013 CFR

2013-10-01

... addition of a strength fillet weld of the size as shown, may be used in Class I systems not exceeding 750... buttwelding flanges must be provided. For Class II piping systems, the size of the strength fillet may be... void spaces is desirable. For systems of Class II, the size of the strength fillet may be limited to a...

46 CFR 56.30-10 - Flanged joints (modifies 104.5.1(a)).

Code of Federal Regulations, 2014 CFR

2014-10-01

... addition of a strength fillet weld of the size as shown, may be used in Class I systems not exceeding 750... buttwelding flanges must be provided. For Class II piping systems, the size of the strength fillet may be... void spaces is desirable. For systems of Class II, the size of the strength fillet may be limited to a...

46 CFR 56.30-10 - Flanged joints (modifies 104.5.1(a)).

Code of Federal Regulations, 2012 CFR

2012-10-01

... addition of a strength fillet weld of the size as shown, may be used in Class I systems not exceeding 750... buttwelding flanges must be provided. For Class II piping systems, the size of the strength fillet may be... void spaces is desirable. For systems of Class II, the size of the strength fillet may be limited to a...

Class Size and Sorting in Market Equilibrium: Theory and Evidence. NBER Working Paper No. 13303

ERIC Educational Resources Information Center

Urquiola, Miguel; Verhoogen, Eric

2007-01-01

This paper examines how schools choose class size and how households sort in response to those choices. Focusing on the highly liberalized Chilean education market, we develop a model in which schools are heterogeneous in an underlying productivity parameter, class size is a component of school quality, households are heterogeneous in income and…

The Class Size Question: A Study at Different Levels of Analysis. ACER Research Monograph No. 26.

ERIC Educational Resources Information Center

Larkin, Anthony I.; Keeves, John P.

The purpose of this investigation was to examine the ways in which class size affected other facets of the educational environment of the classroom. The study focused on the commonly found positive relationship between class size and achievement. The most plausible explanation of the evidence seems to involve the effects of grouping more able…

School Governance, Teacher Incentives, and Pupil-Teacher Ratios: Experimental Evidence from Kenyan Primary Schools. NBER Working Paper No. 17939

ERIC Educational Resources Information Center

Duflo, Esther; Dupas, Pascaline; Kremer, Michael

2012-01-01

We examine a program that enabled Parent-Teacher Associations (PTAs) in Kenya to hire novice teachers on short-term contracts, reducing class sizes in grade one from 82 to 44 on average. PTA teachers earned approximately one-quarter as much as teachers operating under central government civil-service institutions but were absent one day per week…

Using Technology-Assisted Instruction and Assessment to Reduce the Effect of Class Size on Student Outcomes in Undergraduate Mathematics Courses

ERIC Educational Resources Information Center

Gleason, Jim

2012-01-01

The implementation of online texts, videos, homework, and tests has changed the process of instruction in introductory college mathematics courses. With this change, more of the students' learning takes place outside of the traditional college classroom and in places such as tutoring centers and dorm rooms. A combination of chi-square tests--for…

When the Army Got Progressive: The Civil Affairs Training School at Stanford University, 1943-1945

ERIC Educational Resources Information Center

Justice, Benjamin

2011-01-01

They sat in the Cubberley Education Lecture Hall to hear visiting experts. More often they could be found meeting in reduced-size classes, or working on small-group activities. They usually took notes; sometimes they took field trips. They memorized lists and sat for exams, but they also watched films and acted out scenarios. Rather than take…

Microcystin distribution in physical size class separations of natural plankton communities

USGS Publications Warehouse

Graham, J.L.; Jones, J.R.

2007-01-01

Phytoplankton communities in 30 northern Missouri and Iowa lakes were physically separated into 5 size classes (>100 ??m, 53-100 ??m, 35-53 ??m, 10-35 ??m, 1-10 ??m) during 15-21 August 2004 to determine the distribution of microcystin (MC) in size fractionated lake samples and assess how net collections influence estimates of MC concentration. MC was detected in whole water (total) from 83% of takes sampled, and total MC values ranged from 0.1-7.0 ??g/L (mean = 0.8 ??g/L). On average, MC in the > 100 ??m size class comprised ???40% of total MC, while other individual size classes contributed 9-20% to total MC. MC values decreased with size class and were significantly greater in the >100 ??m size class (mean = 0.5 ??g /L) than the 35-53 ??m (mean = 0.1 ??g/L), 10-35 ??m (mean = 0.0 ??g/L), and 1-10 ??m (mean = 0.0 ??g/L) size classes (p < 0.01). MC values in nets with 100-??m, 53-??m, 35-??m, and 10-??m mesh were cumulatively summed to simulate the potential bias of measuring MC with various size plankton nets. On average, a 100-??m net underestimated total MC by 51%, compared to 37% for a 53-??m net, 28% for a 35-??m net, and 17% for a 10-??m net. While plankton nets consistently underestimated total MC, concentration of algae with net sieves allowed detection of MC at low levels (???0.01 ??/L); 93% of lakes had detectable levels of MC in concentrated samples. Thus, small mesh plankton nets are an option for documenting MC occurrence, but whole water samples should be collected to characterize total MC concentrations. ?? Copyright by the North American Lake Management Society 2007.

Social Class and Income Inequality in the United States: Ownership, Authority, and Personal Income Distribution from 1980 to 2010

PubMed Central

Wodtke, Geoffrey T.

2016-01-01

This study outlines a theory of social class based on workplace ownership and authority relations, and it investigates the link between social class and growth in personal income inequality since the 1980s. Inequality trends are governed by changes in between-class income differences, changes in the relative size of different classes, and changes in within-class income dispersion. Data from the General Social Survey are used to investigate each of these changes in turn and to evaluate their impact on growth in inequality at the population level. Results indicate that between-class income differences grew by about 60 percent since the 1980s and that the relative size of different classes remained fairly stable. A formal decomposition analysis indicates that changes in the relative size of different social classes had a small dampening effect and that growth in between-class income differences had a large inflationary effect on trends in personal income inequality. PMID:27087695

Social Class and Income Inequality in the United States: Ownership, Authority, and Personal Income Distribution from 1980 to 2010.

PubMed

Wodtke, Geoffrey T

2016-03-01

This study outlines a theory of social class based on workplace ownership and authority relations, and it investigates the link between social class and growth in personal income inequality since the 1980s. Inequality trends are governed by changes in between-class income differences, changes in the relative size of different classes, and changes in within-class income dispersion. Data from the General Social Survey are used to investigate each of these changes in turn and to evaluate their impact on growth in inequality at the population level. Results indicate that between-class income differences grew by about 60% since the 1980s and that the relative size of different classes remained fairly stable. A formal decomposition analysis indicates that changes in the relative size of different social classes had a small dampening effect and that growth in between-class income differences had a large inflationary effect on trends in personal income inequality.

Thin-plate spline analysis of craniofacial growth in Class I and Class II subjects.

PubMed

Franchi, Lorenzo; Baccetti, Tiziano; Stahl, Franka; McNamara, James A

2007-07-01

To compare the craniofacial growth characteristics of untreated subjects with Class II division 1 malocclusion with those of subjects with normal (Class I) occlusion from the prepubertal through the postpubertal stages of development. The Class II division 1 sample consisted of 17 subjects (11 boys and six girls). The Class I sample also consisted of 17 subjects (13 boys and four girls). Three craniofacial regions (cranial base, maxilla, and mandible) were analyzed on the lateral cephalograms of the subjects in both groups by means of thin-plate spline analysis at T1 (prepubertal) and T2 (postpubertal). Both cross-sectional and longitudinal comparisons were performed on both size and shape differences between the two groups. The results showed an increased cranial base angulation as a morphological feature of Class II malocclusion at the prepubertal developmental phase. Maxillary changes in either shape or size were not significant. Subjects with Class II malocclusion exhibited a significant deficiency in the size of the mandible at the completion of active craniofacial growth as compared with Class I subjects. A significant deficiency in the size of the mandible became apparent in Class II subjects during the circumpubertal period and it was still present at the completion of active craniofacial growth.

Protograph LDPC Codes Over Burst Erasure Channels

NASA Technical Reports Server (NTRS)

Divsalar, Dariush; Dolinar, Sam; Jones, Christopher

2006-01-01

In this paper we design high rate protograph based LDPC codes suitable for binary erasure channels. To simplify the encoder and decoder implementation for high data rate transmission, the structure of codes are based on protographs and circulants. These LDPC codes can improve data link and network layer protocols in support of communication networks. Two classes of codes were designed. One class is designed for large block sizes with an iterative decoding threshold that approaches capacity of binary erasure channels. The other class is designed for short block sizes based on maximizing minimum stopping set size. For high code rates and short blocks the second class outperforms the first class.

Early Elementary Class-Size Reduction: A Neo-Institutional Analysis of the Social, Political, and Economic Influences on State-Level Policymaking.

ERIC Educational Resources Information Center

Mitchell, Ross E.

This paper examines the social, political, and economic factors that influenced the adoption and diffusion of early-elementary school class-size-reduction policies at the state level. It applies a neo-institutional framework to explain the rapid spread of class-size reduction policies throughout many state legislatures and boards of education. It…

Class Size and Student Performance at a Public Research University: A Cross-Classified Model

ERIC Educational Resources Information Center

Johnson, Iryna Y.

2010-01-01

This study addresses several methodological problems that have confronted prior research on the effect of class size on student achievement. Unlike previous studies, this analysis accounts for the hierarchical data structure of student achievement, where grades are nested within classes and students, and considers a wide range of class sizes…

77 FR 10724 - Western Pacific Pelagic Fisheries; American Samoa Longline Limited Entry Program

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-23

... size class falls below the maximum allowed. Six permits are available, as follows: Four in Class A (vessels less than or equal to 40 ft in overall length); and Two in Class D (over 70 ft in overall length... the highest priority to the applicant (for any vessel size class) with the earliest documented...

Thin-plate spline analysis of treatment effects of rapid maxillary expansion and face mask therapy in early Class III malocclusions.

PubMed

Baccetti, T; Franchi, L; McNamara, J A

1999-06-01

An effective morphometric method (thin-plate spline analysis) was applied to evaluate shape changes in the craniofacial configuration of a sample of 23 children with Class III malocclusions in the early mixed dentition treated with rapid maxillary expansion and face mask therapy, and compared with a sample of 17 children with untreated Class III malocclusions. Significant treatment-induced changes involved both the maxilla and the mandible. Major deformations consisted of forward displacement of the maxillary complex from the pterygoid region and of anterior morphogenetic rotation of the mandible, due to a significant upward and forward direction of growth of the mandibular condyle. Significant differences in size changes due to reduced increments in mandibular dimensions were associated with significant shape changes in the treated group.

The effect of mitigation measures on size distributed mass concentrations of atmospheric particles and black carbon concentrations during the Olympic Summer Games 2008 in Beijing.

PubMed

Schleicher, Nina; Norra, Stefan; Dietze, Volker; Yu, Yang; Fricker, Mathieu; Kaminski, Uwe; Chen, Yuan; Cen, Kuang

2011-12-15

The period of the 2008 Olympic Summer Games in Beijing can be considered as a unique opportunity to study the influences of emission reduction measures on air quality improvement. Within this study atmospheric particles of different size classes (2.5 to 80 μm) were investigated before, during, and after the Olympic Games period in order to observe and assess the success of short-term measures to mitigate extreme urban aerosol pollution and also to investigate, which particle size classes were reduced most effectively. Furthermore, black carbon (BC) concentrations in fine particles (PM(2.5)) during the source control period were compared to those of the previous years in order to investigate the decrease of combustion-derived aerosols. It is shown that besides the implemented mitigation measures precipitation decisively contributed to a considerable decrease of particulate air pollution in Beijing compared to the respective concentrations during the time directly before and after the Olympic Games, and also compared to average August concentrations during the previous years and the following year 2009. Particles of the fine fraction of the coarse mode (2.5 to 5 μm), which have a residence time in the order of several days and which, therefore, are typically transported over long distances from outside of Beijing, were less efficiently reduced than coarser particles. This indicates that long-range transport of atmospheric particles is difficult to control and that presumably the established mitigation area was not large enough to also reduce the fine fraction of the coarse mode more efficiently. Furthermore, the study showed that coarse geogenic particles, which originated to a high percentage from construction sites and resuspension processes due to traffic seemed to be reduced most efficiently during the Olympic Games period. Copyright © 2011 Elsevier B.V. All rights reserved.

Independence of the blood pressure lowering effect and efficacy of the angiotensin receptor neprilysin inhibitor, LCZ696, in patients with heart failure with preserved ejection fraction: an analysis of the PARAMOUNT trial.

PubMed

Jhund, Pardeep S; Claggett, Brian; Packer, Milton; Zile, Michael R; Voors, Adriaan A; Pieske, Burkert; Lefkowitz, Martin; Shi, Victor; Bransford, Toni; McMurray, John J V; Solomon, Scott D

2014-06-01

The first in class angiotensin receptor neprilysin inhibitor, LCZ696 has been shown to reduce levels of N-terminal pro-brain natriuretic peptide (NT-proBNP), reduce left atrial size and improve New York Heart Association (NYHA) class in patients with heart failure with preserved ejection fraction (HFpEF). We examined whether the effects of LCZ696 were independent of systolic blood pressure (SBP) lowering. In the Prospective comparison of ARNi (angiotensin receptor neprilysin inhibitor) with ARB (angiotensin receptor blocker) on Management Of heart failUre with preserved ejectioN fracTion (PARAMOUNT) trial 301 patients were randomly assigned to LCZ696 or valsartan. We examined the relationship between SBP lowering and LCZ696 on NT-proBNP level, left atrial size, NYHA class and estimated glomerular filtration rate (eGFR). By 12 weeks blood pressure was reduced by 9 mmHg (SD 15)/5 mmHg (SD 11) in patients receiving LCZ696 in comparison with 3 mmHg (SD 17)/2 mmHg (SD 12) in those receiving valsartan. The change in NT-proBNP was poorly correlated with change in SBP (LCZ696, r = 0.17, P = 0.06; valsartan, r = 0.05, P = 0.58) After adjustment for change in SBP, the ratio of change in NT-proBNP at 12 weeks for LCZ696 vs. valsartan was 0.76 (95% CI 0.63-0.93, P = 0.008), and similar to the ratio not adjusting for SBP (0.76, 95% CI 0.63-0.92, P = 0.006); P for interaction was 0.38). Similarly, reduction in left atrial volume index at 36 weeks, improvement in NYHA class and eGFR were all independent of the change in SBP. In patients with HFpEF, the effect of the angiotensin receptor neprilysin inhibitor LCZ696 on NT-proBNP, left atrial volume, functional class, and eGFR was independent of reduction in SBP. © 2014 The Authors. European Journal of Heart Failure © 2014 European Society of Cardiology.

Effects of structural marsh management and salinity on invertebrate prey of waterbirds in marsh ponds during winter on the Gulf Coast Chenier Plain

USGS Publications Warehouse

Bolduc, F.; Afton, A.D.

2003-01-01

Aquatic invertebrates are important food resources for wintering waterbirds, and prey selection generally is limited by prey size. Aquatic invertebrate communities are influenced by sediments and hydrologic characteristics of wetlands, which were affected by structural marsh management (levees, water-control structures and impoundments; SMM) and salinity on the Gulf Coast Chenier Plain of North America. Based on previous research, we tested general predictions that SMM reduces biomass of infaunal invertebrates and increases that of epifaunal invertebrates and those that tolerate low levels of dissolved oxygen (O2) and salinity. We also tested the general prediction that invertebrate biomass in freshwater, oligohaline, and mesohaline marshes are similar, except for taxa adapted to specific ranges of salinity. Finally, we investigated relationships among invertebrate biomass and sizes, sediment and hydrologic variables, and marsh types. Accordingly, we measured biomass of common invertebrate by three size classes (63 to 199 ??m, 200 to 999 ??m, and ???1000 ??m), sediment variables (carbon content, C:N ratio, hardness, particle size, and O, penetration), and hydrologic variables (salinity, water depth,temperature, 02, and turbidity) in ponds of impounded freshwater (IF), oligohaline (IO), mesohaline (IM), and unimpounded mesohaline (UM) marshes during winters 1997-1998 to 1999-2000 on Rockefeller State Wildlife Refuge, near Grand Chenier, Louisiana, USA. As predicted, an a priori multivariate analysis of variance (MANOVA) contrast indicated that biomass of an infaunal class of invertebrates (Nematoda, 63 to 199 ??m) was greater in UM marsh ponds than in those of IM marshes, and biomass of an epifaunal class of invertebrates (Ostracoda, 200 to 999 ??m) was greater in IM marsh ponds than in those of UM marshes. The observed reduction in Nematoda due to SMM also was consistent with the prediction that SMM reduces invertebrates that do not tolerate low salinity. Furthermore, as predicted, an a priori MANOVA contrast indicated that biomass of a single invertebrate class adapted to low salinity (Oligochaeta, 200 to 999 ??m) was greater in ponds of IF marshes than in those of IO and IM marshes. A canonical correspondence analysis indicated that variation in salinity and O2 penetration best explained differences among sites that maximized biomass of the common invertebrate classes. Salinity was positively correlated with the silt-clay fraction, O2, and O2 penetration, and negatively correlated with water depth, sediment hardness, carbon, and C:N. Nematoda, Foraminifera, and Copepoda generally were associated with UM marsh ponds and high salinity, whereas other invertebrate classes were distributed among impounded marsh ponds and associated with lower salinity. Our results suggest that SMM and salinity have relatively small effects on invertebrate prey of wintering waterbirds in marsh ponds because they affect biomass of Nematoda and Oligochaeta, and few waterbirds consume these invertebrates. ?? 2003, The Society of Wetland Scientists.

Object Classification With Joint Projection and Low-Rank Dictionary Learning.

PubMed

Foroughi, Homa; Ray, Nilanjan; Hong Zhang

2018-02-01

For an object classification system, the most critical obstacles toward real-world applications are often caused by large intra-class variability, arising from different lightings, occlusion, and corruption, in limited sample sets. Most methods in the literature would fail when the training samples are heavily occluded, corrupted or have significant illumination or viewpoint variations. Besides, most of the existing methods and especially deep learning-based methods, need large training sets to achieve a satisfactory recognition performance. Although using the pre-trained network on a generic large-scale data set and fine-tune it to the small-sized target data set is a widely used technique, this would not help when the content of base and target data sets are very different. To address these issues simultaneously, we propose a joint projection and low-rank dictionary learning method using dual graph constraints. Specifically, a structured class-specific dictionary is learned in the low-dimensional space, and the discrimination is further improved by imposing a graph constraint on the coding coefficients, that maximizes the intra-class compactness and inter-class separability. We enforce structural incoherence and low-rank constraints on sub-dictionaries to reduce the redundancy among them, and also make them robust to variations and outliers. To preserve the intrinsic structure of data, we introduce a supervised neighborhood graph into the framework to make the proposed method robust to small-sized and high-dimensional data sets. Experimental results on several benchmark data sets verify the superior performance of our method for object classification of small-sized data sets, which include a considerable amount of different kinds of variation, and may have high-dimensional feature vectors.

Larval nutrition differentially affects adult fitness and Plasmodium development in the malaria vectors Anopheles gambiae and Anopheles stephensi

PubMed Central

2013-01-01

Background Mosquito fitness is determined largely by body size and nutritional reserves. Plasmodium infections in the mosquito and resultant transmission of malaria parasites might be compromised by the vector’s nutritional status. We studied the effects of nutritional stress and malaria parasite infections on transmission fitness of Anopheles mosquitoes. Methods Larvae of Anopheles gambiae sensu stricto and An. stephensi were reared at constant density but with nutritionally low and high diets. Fitness of adult mosquitoes resulting from each dietary class was assessed by measuring body size and lipid, protein and glycogen content. The size of the first blood meal was estimated by protein analysis. Mosquitoes of each dietary class were fed upon a Plasmodium yoelii nigeriensis-infected mouse, and parasite infections were determined 5 d after the infectious blood meal by dissection of the midguts and by counting oocysts. The impact of Plasmodium infections on gonotrophic development was established by dissection. Results Mosquitoes raised under low and high diets emerged as adults of different size classes comparable between An. gambiae and An. stephensi. In both species low-diet females contained less protein, lipid and glycogen upon emergence than high-diet mosquitoes. The quantity of larval diet impacted strongly upon adult blood feeding and reproductive success. The prevalence and intensity of P. yoelii nigeriensis infections were reduced in low-diet mosquitoes of both species, but P. yoelii nigeriensis impacted negatively only on low-diet, small-sized An. gambiae considering survival and egg maturation. There was no measurable fitness effect of P. yoelii nigeriensis on An. stephensi. Conclusions Under the experimental conditions, small-sized An. gambiae expressed high mortality, possibly caused by Plasmodium infections, the species showing distinct physiological concessions when nutrionally challenged in contrast to well-fed, larger siblings. Conversely, An. stephensi was a robust, successful vector regardless of its nutrional status upon emergence. The data suggest that small-sized An. gambiae, therefore, would contribute little to malaria transmission, whereas this size effect would not affect An. stephensi. PMID:24326030

Microbial utilization of nitrogen in cold core eddies: size does matter

NASA Astrophysics Data System (ADS)

McInnes, A.; Messer, L. F.; Laiolo, L.; Laverock, B.; Laczka, O.; Brown, M. V.; Seymour, J.; Doblin, M.

2016-02-01

As the base of the marine food web, and the first step in the biological carbon pump, understanding changes in microbial community composition is essential for predicting changes in the marine nitrogen (N) cycle. Climate change projections suggest that oligotrophic waters will become more stratified with a concomitant shift in microbial community composition based on changes in N supply. In regions of strong boundary currents, eddies could reduce this limitation through nutrient uplift and other forms of eddy mixing. Understanding the preference for different forms of N by microbes is essential for understanding and predicting shifts in the microbial community. This study aims to understand the utilization of different N species within different microbial size fractions as well as understand the preferred source of N to these groups across varying mesoscale and sub-mesoscale features in the East Australian Current (EAC). In June 2015 we sampled microbial communities from three depths (surface, chlorophyll-a maximum and below the mixed layer), in three mesoscale and sub-mesoscale eddy features, as well as two end-point water masses (coastal and oligotrophic EAC water). Particulate matter was analysed for stable C and N isotopes, and seawater incubations with trace amounts of 15NO3, 15NH4, 15N2, 15Urea and 13C were undertaken. All samples were size fractionated into 0.3-2.0 µm, 2.0-10 µm, and >10 µm size classes, encompassing the majority of microbes in these waters. Microbial community composition was also assessed (pigments, flow cytometry, DNA), as well as physical and chemical parameters, to better understand the drivers of carbon fixation and nitrogen utilization across a diversity of water masses and microbial size classes. We observed that small, young features have a greater abundance of larger size classes. We therefore predict that these microbes will preferentially draw down the recently pulsed NO3. Ultimately, the size and age of a feature will determine the N compound utilization and microbial community composition and as the feature grows in size and age a community succession will lead to differential more diverse N compound utilization.

The Implication of Large Class Size in the Teaching and Learning of Business Education in Tertiary Institution in Ekiti State

ERIC Educational Resources Information Center

Ayeni, Olapade Grace; Olowe, Modupe Oluwatoyin

2016-01-01

Large class size is one of the problems in the educational sector that developing nations have been grappling with. Nigeria as a developing nation is no exception. The purpose of this study is to provide views of both lecturers and students on large class size and how it affects teaching and learning in tertiary institutions in Ekiti State of…

Environmental influences and ontogenetic differences in vertical habitat use of black marlin (Istiompax indica) in the southwestern Pacific

PubMed Central

Tracey, Sean R.; Pepperell, Julian G.; Domeier, Michael L.; Bennett, Michael B.

2017-01-01

The black marlin (Istiompax indica) is a highly migratory billfish that occupies waters throughout the tropical and subtropical Indo-Pacific. To characterize the vertical habitat use of I. indica, we examined the temperature-depth profiles collected using 102 pop-up satellite archival tags deployed off the east coast of Australia. Modelling of environmental variables revealed location, sea-surface height deviation, mixed layer depth and dissolved oxygen to all be significant predictors of vertical habitat use. Distinct differences in diel movements were observed between the size classes, with larger size classes of marlin (greater than 50 kg) undertaking predictable bounce-diving activity during daylight hours, while diving behaviour of the smallest size class occurred randomly during both day and night. Overall, larger size classes of I. indica were found to use an increased thermal range and spend more time in waters below 150 m than fish of smaller size classes. The differences in the diving behaviour among size classes were suggested to reflect ontogenetic differences in foraging behaviour or physiology. The findings of this study demonstrate, for the first time to our knowledge, ontogenetic differences in vertical habitat in a species of billfish, and further the understanding of pelagic fish ecophysiology in the presence of global environmental change. PMID:29291060

Study on the biomass and size spectra of bio-particles in vermifilter biofilms.

PubMed

Di, Wanyin; Xing, Meiyan

2018-09-15

In biological processes of sludge treatment, the sludge yield is closely related to the energy dissipation of entire microbial system. The vermifilter (VF), a novel biofilter, works efficiently due to the introduction of earthworms, which modifies the energy flow pathway through the variations of microbial size structure. For a deep insight into the sludge reduction in the VF, the biomass size spectrum (BSS) was employed to map the energy dissipation in the VF. The results indicated that bio-particles in the size class of [31, 63] μm were reduced most in the excess sludge after the VF treatment. In biofilms, bio-particles in the size class of [31, 63] μm varied most with the filter depth and earthworm density. Eight biomass and size spectra (BSS) were established for all beds of the VF and BF (the control of the VF, without earthworms). The normalized BSS were all linear both in the VF and BF, and their linear regression parameters, the slopes (k) and intercepts (b), varied with the filter depth and the earthworm density. The k and b of the VF were both significantly different from those of the BF. According to the k, the productivity level of largest bio-particles was higher in the VF than in the BF. According to the b, bio-particles at the bottom of size structure could be taken faster in the VF than in the BF. At last, some improvement approaches with some tries were proposed to enhance the sludge treatment capacity of the VF. Copyright © 2018 Elsevier B.V. All rights reserved.

Variations in tooth size and arch dimensions in Malay schoolchildren.

PubMed

Hussein, Khalid W; Rajion, Zainul A; Hassan, Rozita; Noor, Siti Noor Fazliah Mohd

2009-11-01

To compare the mesio-distal tooth sizes and dental arch dimensions in Malay boys and girls with Class I, Class II and Class III malocclusions. The dental casts of 150 subjects (78 boys, 72 girls), between 12 and 16 years of age, with Class I, Class II and Class III malocclusions were used. Each group consisted of 50 subjects. An electronic digital caliper was used to measure the mesio-distal tooth sizes of the upper and lower permanent teeth (first molar to first molar), the intercanine and intermolar widths. The arch lengths and arch perimeters were measured with AutoCAD software (Autodesk Inc., San Rafael, CA, U.S.A.). The mesio-distal dimensions of the upper lateral incisors and canines in the Class I malocclusion group were significantly smaller than the corresponding teeth in the Class III and Class II groups, respectively. The lower canines and first molars were significantly smaller in the Class I group than the corresponding teeth in the Class II group. The lower intercanine width was significantly smaller in the Class II group as compared with the Class I group, and the upper intermolar width was significantly larger in Class III group as compared with the Class II group. There were no significant differences in the arch perimeters or arch lengths. The boys had significantly wider teeth than the girls, except for the left lower second premolar. The boys also had larger upper and lower intermolar widths and lower intercanine width than the girls. Small, but statistically significant, differences in tooth sizes are not necessarily accompanied by significant arch width, arch length or arch perimeter differences. Generally, boys have wider teeth, larger lower intercanine width and upper and lower intermolar widths than girls.

Differences in xylogenesis between dominant and suppressed trees.

PubMed

Liu, Shushan; Li, Xiaoxia; Rossi, Sergio; Wang, Lily; Li, Wei; Liang, Eryuan; Leavitt, Steven W

2018-05-01

Most dendroecological studies focus on dominant trees, but little is known about the growing season of trees belonging to different size classes and their sensitivity to biotic factors. The objective of this study was to compare the dynamics of xylem formation between dominant and suppressed trees of Abies fabri of similar age growing in the Gongga Mountains, southeastern Tibetan Plateau, and to identify the association between xylem growth and climate. The timing and duration of xylogenesis in histological sections were investigated weekly during the 2013-2015 growing seasons. Our investigation found that timing and duration of xylogenesis varied with canopy position and its associated tree size. Xylogenesis started 6-14 days earlier, and ended 5-11 days later in dominant trees than in suppressed trees, resulting in a significantly longer growing season. Dominant trees also exhibited higher temperature sensitivity of tracheid production rate than suppressed trees. The observed differences in xylogenesis among trees suggested that competition affects tree growth by reducing the growing period in suppressed trees. Representative climate-growth relationships should involve trees of all size classes when evaluating the effects of the environment on forest dynamics. © 2018 Botanical Society of America.

Agro-forest landscape and the 'fringe' city: a multivariate assessment of land-use changes in a sprawling region and implications for planning.

PubMed

Salvati, Luca

2014-08-15

The present study evaluates the impact of urban expansion on landscape transformations in Rome's metropolitan area (1500 km(2)) during the last sixty years. Landscape composition, structure and dynamics were assessed for 1949 and 2008 by analyzing the distribution of 26 metrics for nine land-use classes. Changes in landscape structure are analysed by way of a multivariate statistical approach providing a summary measure of rapidity-to-change for each metric and class. Land fragmentation increased during the study period due to urban expansion. Poorly protected or medium-low value added classes (vineyards, arable land, olive groves and pastures) experienced fragmentation processes compared with protected or high-value added classes (e.g. forests, olive groves) showing larger 'core' areas and lower fragmentation. The relationship observed between class area and mean patch size indicates increased fragmentation for all uses of land (both expanding and declining) except for urban areas and forests. Reducing the impact of urban expansion for specific land-use classes is an effective planning strategy to contrast the simplification of Mediterranean landscape in peri-urban areas. Copyright © 2014 Elsevier B.V. All rights reserved.

Class Size Reduction and Urban Students. ERIC Digest.

ERIC Educational Resources Information Center

Schwartz, Wendy

Researchers have long investigated whether smaller classes improve student achievement. Their conclusions suggest that class size reduction (CSR) can result in greater in-depth coverage of subject matter by teachers, enhanced learning and stronger engagement by students, more personalized teacher-student relationships, and safer schools with fewer…

An Analysis of the Effects of Class Size on Student Achievement in Selected Middle Schools in the Sandhills Region of North Carolina

ERIC Educational Resources Information Center

Maples, Jeffrey B.

2009-01-01

The purpose of this study was to analyze the effects of class size and student achievement in mathematics and reading. The study focused on grades 6 through 8 and used the results of the North Carolina EOG tests in mathematics and reading for the academic year 2006-2007. This study examined the effects of class size and student achievement in…

Longitudinal Effects of Class Size Reductions on Attainment: Results from Hong Kong Primary Classrooms

ERIC Educational Resources Information Center

Galton, Maurice; Pell, Tony

2012-01-01

In a four-year study of the effect of class size on pupil outcomes in a sample of 36 primary schools in Hong Kong, it has been found that there are few positive differences in attainment between classes set at less than 25 pupils and those of normal size averaging 38. Three cohorts of pupils were studied. In Cohort 1 pupils spent 3 years in small…

Class Size Effects on Literacy Skills and Literacy Interest in First Grade: A Large-Scale Investigation

ERIC Educational Resources Information Center

Ecalle, Jean; Magnan, Annie; Gibert, Fabienne

2006-01-01

This article examines the impact of class size on literacy skills and on literacy interest in beginning readers from zones with specific educational needs in France. The data came from an experiment involving first graders in which teachers and pupils were randomly assigned to the different class types (small classes of 10-12 pupils vs. regular…

The Effect of Large Classes on English Teaching and Learning in Saudi Secondary Schools

ERIC Educational Resources Information Center

Bahanshal, Dalal A.

2013-01-01

The effect of class size on teaching and learning English as a foreign language (EFL) has been through a contentious debate among researchers for a long time. Before the 1950's the concern about the effect of class size and the learning outcomes of students in such classes waned for some time. Yet, researchers have reconsidered the case once again…

Cost-Driven Design of a Large Scale X-Plane

NASA Technical Reports Server (NTRS)

Welstead, Jason R.; Frederic, Peter C.; Frederick, Michael A.; Jacobson, Steven R.; Berton, Jeffrey J.

2017-01-01

A conceptual design process focused on the development of a low-cost, large scale X-plane was developed as part of an internal research and development effort. One of the concepts considered for this process was the double-bubble configuration recently developed as an advanced single-aisle class commercial transport similar in size to a Boeing 737-800 or Airbus A320. The study objective was to reduce the contractor cost from contract award to first test flight to less than $100 million, and having the first flight within three years of contract award. Methods and strategies for reduced cost are discussed.

VPS GRCop-84 Liner Development Efforts

NASA Technical Reports Server (NTRS)

Elam, Sandra K.; Holmes, Richard; McKechnie, Tim; Hickman, Robert; Pickens, Tim

2003-01-01

For the past several years, NASA's Marshall Space Flight Center (MSFC) has been working with Plasma Processes, Inc. (PPI) to fabricate combustion chamber liners using the Vacuum Plasma Spray (VPS) process. Multiple liners of a variety of shapes and sizes have been created. Each liner has been fabricated with GRCop-84 (a copper alloy with chromium and niobium) and a functional gradient coating (FGC) on the hot wall. While the VPS process offers versatility and a reduced fabrication schedule, the material system created with VPS allows the liners to operate at higher temperatures, with maximum blanch resistance and improved cycle life. A subscal unit (5K lbf thrust class) is being cycle tested in a LOX/Hydrogen thrust chamber assembly at MSFC. To date, over 75 hot-fire tests have been accumulated on this article. Tests include conditions normally detrimental to conventional materials, yet the VPS GRCop-84 liner has yet to show any signs of degradation. A larger chamber (15K lbf thrust class) has also been fabricated and is being prepared for hot-fire testing at MSFC near the end of 2003. Linear liners have been successfully created to further demonstrate the versatility of the process. Finally, scale up issues for the VPS process are being tackled with efforts to fabricate a full size, engine class liner. Specifically, a liner for the SSME's Main Combustion Chamber (MCC) has recently been attempted. The SSME size was chosen for convenience, since its design was readily available and its size was sufficient to tackle specific issues. Efforts to fabricate these large liners have already provided valuable lessons for using this process for engine programs. The material quality for these large units is being evaluated with destructive analysis and these results will be available by the end of 2003.

Why Does Rebalancing Class-Unbalanced Data Improve AUC for Linear Discriminant Analysis?

PubMed

Xue, Jing-Hao; Hall, Peter

2015-05-01

Many established classifiers fail to identify the minority class when it is much smaller than the majority class. To tackle this problem, researchers often first rebalance the class sizes in the training dataset, through oversampling the minority class or undersampling the majority class, and then use the rebalanced data to train the classifiers. This leads to interesting empirical patterns. In particular, using the rebalanced training data can often improve the area under the receiver operating characteristic curve (AUC) for the original, unbalanced test data. The AUC is a widely-used quantitative measure of classification performance, but the property that it increases with rebalancing has, as yet, no theoretical explanation. In this note, using Gaussian-based linear discriminant analysis (LDA) as the classifier, we demonstrate that, at least for LDA, there is an intrinsic, positive relationship between the rebalancing of class sizes and the improvement of AUC. We show that the largest improvement of AUC is achieved, asymptotically, when the two classes are fully rebalanced to be of equal sizes.

Connecting in Class? College Class Size and Inequality in Academic Social Capital

ERIC Educational Resources Information Center

Beattie, Irenee R.; Thiele, Megan

2016-01-01

College students who interact with professors and peers about academic matters have better college outcomes. Although institutional factors influence engagement, prior scholarship has not systematically examined whether class sizes affect students' academic interactions, nor whether race or first-generation status moderate such effects. We…

The Allocation of Teachers in Schools--An Alternative to the Class Size Dialogue.

ERIC Educational Resources Information Center

Loader, David N.

1978-01-01

This article looks beyond class size to such specifics as teachers' load, subject electives available, subject load, and different class groupings in developing a flow chart that gives added understanding and control over the variables relating to the deployment of teachers. (Author/IRT)

Making Class Size Work in the Middle Grades

ERIC Educational Resources Information Center

Tienken, C. H.; Achilles, C. M.

2006-01-01

Most research on the positive effects of class-size reduction (CSR) has occurred in the elementary level (Word, Johnston, Bain, Fulton, Zaharias, Lintz, Achilles, Folger, & Breda, 1990; Molnar, Smith, Zahorik, Palmer, Halbach, & Ehrle, 1999). Is CSR an important variable in improving education in the middle grades? Can small classes be…

All We Need Is a Little Class.

ERIC Educational Resources Information Center

Krieger, Jean D.

This study was designed to discover the nature of interactions between effective teachers in regular-sized classes with 25 or more students and small-size classes with fewer than 18 students. Eleven public school primary classrooms were observed, and the interactions between the teacher and students were studied. Verbal and nonverbal interactions…

The Non-Cognitive Returns to Class Size

ERIC Educational Resources Information Center

Dee, Thomas S.; West, Martin R.

2011-01-01

The authors use nationally representative survey data and a research design that relies on contemporaneous within-student and within-teacher comparisons across two academic subjects to estimate how class size affects certain non-cognitive skills in middle school. Their results indicate that smaller eighth-grade classes are associated with…

Social class and family size as determinants of attributed machismo, femininity, and family planning: a field study in two South American communities.

PubMed

Nicassio, P M

1977-12-01

A study was conducted to determine the way in which stereotypes of machismo and femininity are associated with family size and perceptions of family planning. A total of 144 adults, male and female, from a lower class and an upper middle class urban area in Colombia were asked to respond to photographs of Colombian families varying in size and state of completeness. The study illustrated the critical role of sex-role identity and sex-role organization as variables having an effect on fertility. The lower-class respondents described parents in the photographs as significantly more macho or feminine because of their children than the upper-middle-class subjects did. Future research should attempt to measure when this drive to sex-role identity is strongest, i.e., when men and women are most driven to reproduce in order to "prove" themselves. Both lower- and upper-middle-class male groups considered male dominance in marriage to be directly linked with family size. Perceptions of the use of family planning decreased linearly with family size for both social groups, although the lower-class females attributed more family planning to spouses of large families than upper-middle-class females. It is suggested that further research deal with the ways in which constructs of machismo and male dominance vary between the sexes and among socioeconomic groups and the ways in which they impact on fertility.

Dynamic relationships between body size, species richness, abundance, and energy use in a shallow marine epibenthic faunal community

PubMed Central

Labra, Fabio A; Hernández-Miranda, Eduardo; Quiñones, Renato A

2015-01-01

We study the temporal variation in the empirical relationships among body size (S), species richness (R), and abundance (A) in a shallow marine epibenthic faunal community in Coliumo Bay, Chile. We also extend previous analyses by calculating individual energy use (E) and test whether its bivariate and trivariate relationships with S and R are in agreement with expectations derived from the energetic equivalence rule. Carnivorous and scavenger species representing over 95% of sample abundance and biomass were studied. For each individual, body size (g) was measured and E was estimated following published allometric relationships. Data for each sample were tabulated into exponential body size bins, comparing species-averaged values with individual-based estimates which allow species to potentially occupy multiple size classes. For individual-based data, both the number of individuals and species across body size classes are fit by a Weibull function rather than by a power law scaling. Species richness is also a power law of the number of individuals. Energy use shows a piecewise scaling relationship with body size, with energetic equivalence holding true only for size classes above the modal abundance class. Species-based data showed either weak linear or no significant patterns, likely due to the decrease in the number of data points across body size classes. Hence, for individual-based size spectra, the SRA relationship seems to be general despite seasonal forcing and strong disturbances in Coliumo Bay. The unimodal abundance distribution results in a piecewise energy scaling relationship, with small individuals showing a positive scaling and large individuals showing energetic equivalence. Hence, strict energetic equivalence should not be expected for unimodal abundance distributions. On the other hand, while species-based data do not show unimodal SRA relationships, energy use across body size classes did not show significant trends, supporting energetic equivalence. PMID:25691966

Class size as related to the use of technology, educational practices, and outcomes in Web-based nursing courses.

PubMed

Burruss, Nancy M; Billings, Diane M; Brownrigg, Vicki; Skiba, Diane J; Connors, Helen R

2009-01-01

With the expanding numbers of nursing students enrolled in Web-based courses and the shortage of faculty, class sizes are increasing. This exploratory descriptive study examined class size in relation to the use of technology and to particular educational practices and outcomes. The sample consisted of undergraduate (n = 265) and graduate (n = 863) students enrolled in fully Web-based nursing courses. The Evaluating Educational Uses of Web-based Courses in Nursing survey (Billings, D., Connors, H., Skiba, D. (2001). Benchmarking best practices in Web-based nursing courses. Advances in Nursing Science, 23, 41--52) and the Social Presence Scale (Gunawardena, C. N., Zittle, F. J. (1997). Social presence as a predictor of satisfaction within a computer-mediated conferencing environment. The American Journal of Distance Education, 11, 9-26.) were used to gather data about the study variables. Class sizes were defined as very small (1 to 10 students), small (11 to 20 students), medium (21 to 30 students), large (31 to 40 students), and very large (41 students and above). Descriptive and inferential statistics were used to analyze the data. There were significant differences by class size in students' perceptions of active participation in learning, student-faculty interaction, peer interaction, and connectedness. Some differences by class size between undergraduate and graduate students were also found, and these require further study.

Confinement of surface waves at the air-water interface to control aerosol size and dispersity

NASA Astrophysics Data System (ADS)

Nazarzadeh, Elijah; Wilson, Rab; King, Xi; Reboud, Julien; Tassieri, Manlio; Cooper, Jonathan M.

2017-11-01

The precise control over the size and dispersity of droplets, produced within aerosols, is of great interest across many manufacturing, food, cosmetic, and medical industries. Amongst these applications, the delivery of new classes of high value drugs to the lungs has recently attracted significant attention from pharmaceutical companies. This is commonly achieved through the mechanical excitation of surface waves at the air liquid interface of a parent liquid volume. Previous studies have established a correlation between the wavelength on the surface of liquid and the final aerosol size. In this work, we show that the droplet size distribution of aerosols can be controlled by constraining the liquid inside micron-sized cavities and coupling surface acoustic waves into different volumes of liquid inside micro-grids. In particular, we show that by reducing the characteristic physical confinement size (i.e., either the initial liquid volume or the cavities' diameters), higher harmonics of capillary waves are revealed with a consequent reduction of both aerosol mean size and dispersity. In doing so, we provide a new method for the generation and fine control of aerosols' sizes distribution.

Early Implementation of the Class Size Reduction Initiative.

ERIC Educational Resources Information Center

Illig, David C.

A survey of school districts was conducted to determine the initial progress and problems associated with the 1997 Class Size Reduction (CSR) Initiative. Data reveal that most school districts had enough space for smaller classes for at least two grade levels; small school districts were much less likely to report space constraints. The CSR did…

Student Ratings of Instruction: Examining the Role of Academic Field, Course Level, and Class Size

ERIC Educational Resources Information Center

Laughlin, Anne M.

2014-01-01

This dissertation investigated the relationship between course characteristics and student ratings of instruction at a large research intensive university. Specifically, it examined the extent to which academic field, course level, and class size were associated with variation in mean class ratings. Past research consistently identifies…

The Relationship of Class Size Effects and Teacher Salary

ERIC Educational Resources Information Center

Peevely, Gary; Hedges, Larry; Nye, Barbara A.

2005-01-01

The effects of class size on academic achievement have been studied for decades. Although the results of small-scale, randomized experiments and large-scale, econometric studies point to positive effects of small classes, some scholars see the evidence as ambiguous. Recent analyses from a 4-year, large-scale, randomized experiment on the effects…

Class Size: Teachers' Perspectives

ERIC Educational Resources Information Center

Watson, Kevin; Handal, Boris; Maher, Marguerite

2016-01-01

A consistent body of research shows that large classes have been perceived by teachers as an obstacle to deliver quality teaching. This large-scale study sought to investigate further those differential effects by asking 1,119 teachers from 321 K-12 schools in New South Wales (Australia) their perceptions of ideal class size for a variety of…

Symmetry breaking in two interacting populations of quadratic integrate-and-fire neurons.

PubMed

Ratas, Irmantas; Pyragas, Kestutis

2017-10-01

We analyze the dynamics of two coupled identical populations of quadratic integrate-and-fire neurons, which represent the canonical model for class I neurons near the spiking threshold. The populations are heterogeneous; they include both inherently spiking and excitable neurons. The coupling within and between the populations is global via synapses that take into account the finite width of synaptic pulses. Using a recently developed reduction method based on the Lorentzian ansatz, we derive a closed system of equations for the neuron's firing rates and the mean membrane potentials in both populations. The reduced equations are exact in the infinite-size limit. The bifurcation analysis of the equations reveals a rich variety of nonsymmetric patterns, including a splay state, antiphase periodic oscillations, chimera-like states, and chaotic oscillations as well as bistabilities between various states. The validity of the reduced equations is confirmed by direct numerical simulations of the finite-size networks.

Symmetry breaking in two interacting populations of quadratic integrate-and-fire neurons

NASA Astrophysics Data System (ADS)

Ratas, Irmantas; Pyragas, Kestutis

2017-10-01

We analyze the dynamics of two coupled identical populations of quadratic integrate-and-fire neurons, which represent the canonical model for class I neurons near the spiking threshold. The populations are heterogeneous; they include both inherently spiking and excitable neurons. The coupling within and between the populations is global via synapses that take into account the finite width of synaptic pulses. Using a recently developed reduction method based on the Lorentzian ansatz, we derive a closed system of equations for the neuron's firing rates and the mean membrane potentials in both populations. The reduced equations are exact in the infinite-size limit. The bifurcation analysis of the equations reveals a rich variety of nonsymmetric patterns, including a splay state, antiphase periodic oscillations, chimera-like states, and chaotic oscillations as well as bistabilities between various states. The validity of the reduced equations is confirmed by direct numerical simulations of the finite-size networks.

Food and disturbance effects on Arctic benthic biomass and production size spectra

NASA Astrophysics Data System (ADS)

Górska, Barbara; Włodarska-Kowalczuk, Maria

2017-03-01

Body size is a fundamental biological unit that is closely coupled to key ecological properties and processes. At the community level, changes in size distributions may influence energy transfer pathways in benthic food webs and ecosystem carbon cycling; nevertheless they remain poorly explored in benthic systems, particularly in the polar regions. Here, we present the first assessment of the patterns of benthic biomass size spectra in Arctic coastal sediments and explore the effects of glacial disturbance and food availability on the partitioning of biomass and secondary productivity among size-defined components of benthic communities. The samples were collected in two Arctic fjords off west Spitsbergen (76 and 79°N), at 6 stations that represent three regimes of varying food availability (indicated by chlorophyll a concentration in the sediments) and glacial sedimentation disturbance intensity (indicated by sediment accumulation rates). The organisms were measured using image analysis to assess the biovolume, biomass and the annual production of each individual. The shape of benthic biomass size spectra at most stations was bimodal, with the location of a trough and peaks similar to those previously reported in lower latitudes. In undisturbed sediments macrofauna comprised 89% of the total benthic biomass and 56% of the total production. The lower availability of food resources seemed to suppress the biomass and secondary production across the whole size spectra (a 6-fold decrease in biomass and a 4-fold decrease in production in total) rather than reshape the spectrum. At locations where poor nutritional conditions were coupled with disturbance, the biomass was strongly reduced in selected macrofaunal size classes (class 10 and 11), while meiofaunal biomass and production were much higher, most likely due to a release from macrofaunal predation and competition pressure. As a result, the partitioning of benthic biomass and production shifted towards meiofauna (39% of biomass and 83% of production), which took over the benthic metazoan key-player role in terms of processing organic matter in sediments. Macrofaunal nematodes composed a considerable portion of the benthic community in terms of biomass (up to 9%) and production (up to 12%), but only in undisturbed sediments with high organic matter content. Our study indicates that food availability and disturbance controls the total bulk and partitioning of biomass and production among the size classes in Arctic benthic communities.

Power laws, discontinuities and regional city size distributions

USGS Publications Warehouse

Garmestani, A.S.; Allen, Craig R.; Gallagher, C.M.

2008-01-01

Urban systems are manifestations of human adaptation to the natural environment. City size distributions are the expression of hierarchical processes acting upon urban systems. In this paper, we test the entire city size distributions for the southeastern and southwestern United States (1990), as well as the size classes in these regions for power law behavior. We interpret the differences in the size of the regional city size distributions as the manifestation of variable growth dynamics dependent upon city size. Size classes in the city size distributions are snapshots of stable states within urban systems in flux.

The Effects of Instructor Participation and Class Size on Student Participation in an Online Class Discussion Forum

ERIC Educational Resources Information Center

Parks-Stamm, Elizabeth J.; Zafonte, Maria; Palenque, Stephanie M.

2017-01-01

Student participation in online discussion forums is associated with positive outcomes for student achievement and satisfaction, but research findings on the impact of class size and instructors' participation on student participation have been mixed. The present study analyzed the frequency of instructor and student posts in asynchronous…

A Descriptive Evaluation of the Federal Class-Size Reduction Program: Final Report

ERIC Educational Resources Information Center

Millsap, Mary Ann; Giancola, Jennifer; Smith, W. Carter; Hunt, Dana; Humphrey, Daniel C.; Wechsler, Marjorie E.; Riehl, Lori M.

2004-01-01

The federal Class-Size Reduction (CSR) Program, P.L. 105-277, begun in Fiscal Year 1999, represented a major federal commitment to help school districts hire additional qualified teachers, especially in the early elementary grades, so children would learn in smaller classes. The CSR program also allowed funds to be spent as professional…

Class-Size Effects on Adolescents' Mental Health and Well-Being in Swedish Schools

ERIC Educational Resources Information Center

Jakobsson, Niklas; Persson, Mattias; Svensson, Mikael

2013-01-01

This paper analyzes whether class size has an effect on the prevalence of mental health problems and well-being among adolescents in Swedish schools. We use cross-sectional data collected in year 2008 covering 2755 Swedish adolescents in ninth grade from 40 schools and 159 classes. We utilize different econometric approaches to address potential…

Utilizing Online Education in Florida to Meet Mandated Class Size Limitations

ERIC Educational Resources Information Center

Mattox, Kari Ann

2012-01-01

With the passage of a state constitutional amendment in 2002, Florida school districts faced the challenge of meeting class size mandates in core subjects, such as mathematics, English, and science by the 2010-2011 school year, or face financial penalties. Underpinning the amendment's goals was the argument that smaller classes are more effective…

Three Essays on the Economics of Education: Class-Size Reduction, Teacher Labor Markets, and Teacher Effectiveness

ERIC Educational Resources Information Center

Dieterle, Steven

2012-01-01

Prior research has established the potential for achievement gains from attending smaller classes. However, large statewide class-size reduction (CSR) policies have not been found to consistently realize such gains. A leading explanation for the disappointing performance of CSR policies is that schools are forced to hire additional teachers of…

Class Size: Can School Districts Capitalize on the Benefits of Smaller Classes?

ERIC Educational Resources Information Center

Hertling, Elizabeth; Leonard, Courtney; Lumsden, Linda; Smith, Stuart C.

2000-01-01

This report is intended to help policymakers understand the benefits of class-size reduction (CSR). It assesses the costs of CSR, considers some research-based alternatives, and explores strategies that will help educators realize the benefits of CSR when it is implemented. It examines how CSR enhances student achievement, such as when the…

Class Size Reduction: Lessons Learned from Experience. Policy Brief No. Twenty-Three.

ERIC Educational Resources Information Center

McRobbie, Joan; Finn, Jeremy D.; Harman, Patrick

New federal proposals have fueled national interest in class-size reduction (CSR). However, CSR raises numerous concerns, some of which are addressed in this policy brief. The text draws on the experiences of states and districts that have implemented CSR. The brief addresses the following 15 concerns: Do small classes in and of themselves affect…

Experimental Estimates of the Impacts of Class Size on Test Scores: Robustness and Heterogeneity

ERIC Educational Resources Information Center

Ding, Weili; Lehrer, Steven F.

2011-01-01

Proponents of class size reductions (CSRs) draw heavily on the results from Project Student/Teacher Achievement Ratio to support their initiatives. Adding to the political appeal of these initiative are reports that minority and economically disadvantaged students received the largest benefits from smaller classes. We extend this research in two…

Health Science students' evaluation of courses and Instructors: the effect of response rate and class size interaction.

PubMed

Kuwaiti, Ahmed Al

2015-01-01

This study aims at investigating the effect of response rate and class size interaction on students' evaluation of instructors and the courses offered at heath science colleges in Saudi Arabia. A retrospective study design was adapted to ascertain Course Evaluation Surveys (CES) conducted at the health science colleges of the University of Dammam [UOD] in the academic year 2013-2014. Accordingly, the CES data which was downloaded from an exclusive online application 'UDQUEST' which includes 337 different courses and 15,264 surveys were utilized in this study. Two-way analysis of variance was utilized to test whether there is any significant interaction between the class size and the response rate on the students' evaluation of courses and instructors. The study showed that high response rate is required for student evaluation of instructors at Health Science colleges when the class size is small whereas a medium response rate is required for students' evaluation of courses. On the other hand, when the class size is medium, a medium or high response rate is needed for students' evaluation of both instructors and courses. The results of this study recommend that the administrators of the health science colleges to be aware of the interpretation of students' evaluations of courses and instructors. The study also suggests that the interaction between response rate and class size is a very important factor that needs to be taken into consideration while interpreting the findings of the students' evaluation of instructors and courses.

Rethinking police training policies: large class sizes increase risk of police sexual misconduct.

PubMed

Reingle Gonzalez, Jennifer M; Bishopp, Stephen A; Jetelina, Katelyn K

2016-09-01

The limited research on police sexual misconduct (PSM), a common form of police misconduct, suggests that no evidence-based strategies for prevention are available for use by police departments. To identify new avenues for prevention, we critically evaluated 'front-end' police recruiting, screening, hiring and training procedures. Internal Affairs records were linked with administrative reports and police academy graduation data for officers accused of sexual assault or misconduct between 1994 and 2014. Logistic and proportional hazards regression methods were used to identify predictors of discharge for sustained allegations of PSM and time to discharge, respectively. Officer's graduating class size was positively associated with odds of discharge for PSM. For every one-officer increase in class size, the rate of discharge for PSM increased by 9% [hazard ratio (HR) = 1.09, P < 0.01]. For particularly large classes (>35 graduates), discharge rates were at least four times greater than smaller classes (HR = 4.43, P < 0.05). Large class sizes and more annual graduates increase rates of PSM. Officer recruitment strategies or training quality may be compromised during periods of intensive hiring. Trainee to instructor ratios or maximum class sizes may be instituted by academies to ensure that all police trainees receive the required supervision, one-on-one training, feedback and attention necessary to maximize public safety. © The Author 2015. Published by Oxford University Press on behalf of Faculty of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Mapped Plot Patch Size Estimates

Treesearch

Paul C. Van Deusen

2005-01-01

This paper demonstrates that the mapped plot design is relatively easy to analyze and describes existing formulas for mean and variance estimators. New methods are developed for using mapped plots to estimate average patch size of condition classes. The patch size estimators require assumptions about the shape of the condition class, limiting their utility. They may...

Mars exploration, Venus swingby and conjunction class mission modes, time period 2000 to 2045

NASA Technical Reports Server (NTRS)

Young, A. C.; Mulqueen, J. A.; Skinner, J. E.

1984-01-01

Trajectory and mission requirement data are presented for Earth-Mars opposition class and conjunction class round trip stopover mission opportunities available during the time period year 2000 to year 2045. The opposition class mission employs the gravitational field of Venus to accelerate the space vehicle on either the outbound or inbound leg. The gravitational field of Venus was used to reduce the propulsion requirement associated with the opposition class mission. Representative space vehicle systems are sized to compare the initial mass required in low Earth orbit of one mission opportunity with another mission opportunity. The interplanetary space vehicle is made up of the spacecraft and the space vehicle acceleration system. The space vehicle acceleration system consists of three propulsion stages. The first propulsion stage performs the Earth escape maneuver; the second stage brakes the spacecraft and Earth braking stage into the Mars elliptical orbit and effects the escape maneuver from the Mars elliptical orbit. The third propulsion stage brakes the mission module into an elliptical orbit at Earth return. The interplanetary space vehicle was assumed to be assembled in and depart from the space station circular orbit.

Interactive effects of water temperature and salinity on growth and mortality of eastern oysters, Crassostrea virginica: A meta-analysis using 40 years of monitoring data

USGS Publications Warehouse

Lowe, Michael R.; Sehlinger, Troy; Soniat, Thomas M.; LaPeyre, Megan K.

2017-01-01

Despite nearly a century of exploitation and scientific study, predicting growth and mortality rates of the eastern oyster (Crassostrea virginica) as a means to inform local harvest and management activities remains difficult. Ensuring that models reflect local population responses to varying salinity and temperature combinations requires locally appropriate models. Using long-term (1988 to 2015) monitoring data from Louisiana's public oyster reefs, we develop regionally specific models of temperature- and salinity-driven mortality (sack oysters only) and growth for spat (<25 mm), seed (25–75 mm), and sack (>75 mm) oyster size classes. The results demonstrate that the optimal combination of temperature and salinity where Louisiana oysters experience reduced mortality and fast growth rates is skewed toward lower salinities and higher water temperatures than previous models have suggested. Outside of that optimal range, oysters are commonly exposed to combinations of temperature and salinity that are correlated with high mortality and reduced growth. How these combinations affect growth, and to a lesser degree mortality, appears to be size class dependent. Given current climate predictions for the region and ongoing large-scale restoration activities in coastal Louisiana, the growth and mortality models are a critical step toward ensuring sustainable oyster reefs for long-term harvest and continued delivery of the ecological services in a changing environment.

Declining survival of lake trout stocked during 1963-1986 in U.S. waters of Lake Superior

USGS Publications Warehouse

Hansen, Michael J.; Ebener, Mark P.; Schorfhaar, Richard G.; Schram, Stephen T.; Schreiner, Donald R.; Selgeby, James H.

1994-01-01

The average catch per effort (CPE) values for the 1963–1982 year-classes of stocked lake trout Salvelinus namaycush caught at age 7 in gill nets and for the 1976–1986 year-classes caught at ages 2–4 in trawls declined significantly in U.S. waters of Lake Superior. The declines in CPE were not explained by reduced stocking, but rather by significant declines in survival indices of the year-classes of stocked lake trout. Increases in mortality occurred in year-classes before the fish reached ages 2–4, before they were recruited into the sport and commercial fisheries, and before they reached sizes vulnerable to sea lamprey predation. We conclude that declining abundance of stocked lake trout resulted from increased mortality, which may have been caused by competition, predation, or by a combination of these and other factors. Restoration of lake trout in Lake Superior may now depend on prudent management of naturally reproducing stocks rather than on stocking of hatchery-reared fish.

The Effectiveness of School-Type Classes Compared to the Traditional Lecture/Tutorial Method for Teaching Quantitative Methods to Business Students.

ERIC Educational Resources Information Center

Goldfinch, Judy

1996-01-01

A study compared the effectiveness of two methods (medium-size class instruction and large lectures with tutorial sessions) for teaching mathematics and statistics to first-year business students. Students and teachers overwhelmingly preferred the medium-size class method, which produced higher exam scores but had no significant effect on…

Class-Size Reduction: Using What's Been Learned To Inform Educational Decisions. The Informed Educator Series.

ERIC Educational Resources Information Center

Boniface, Russell; Protheroe, Nancy

Class-size reduction (CSR) has been a complex and contentious issue for the last quarter century. Although the small-class concept was adopted because it appealed to common sense, research over time has revealed a mix of confounding variables, instead of a definitive conclusion. Some CSR efforts, such as Tennessee's Project STAR and Wisconsin's…

The role of heterogeneity in contact timing and duration in network models of influenza spread in schools

PubMed Central

Toth, Damon J. A.; Leecaster, Molly; Pettey, Warren B. P.; Gundlapalli, Adi V.; Gao, Hongjiang; Rainey, Jeanette J.; Uzicanin, Amra; Samore, Matthew H.

2015-01-01

Influenza poses a significant health threat to children, and schools may play a critical role in community outbreaks. Mathematical outbreak models require assumptions about contact rates and patterns among students, but the level of temporal granularity required to produce reliable results is unclear. We collected objective contact data from students aged 5–14 at an elementary school and middle school in the state of Utah, USA, and paired those data with a novel, data-based model of influenza transmission in schools. Our simulations produced within-school transmission averages consistent with published estimates. We compared simulated outbreaks over the full resolution dynamic network with simulations on networks with averaged representations of contact timing and duration. For both schools, averaging the timing of contacts over one or two school days caused average outbreak sizes to increase by 1–8%. Averaging both contact timing and pairwise contact durations caused average outbreak sizes to increase by 10% at the middle school and 72% at the elementary school. Averaging contact durations separately across within-class and between-class contacts reduced the increase for the elementary school to 5%. Thus, the effect of ignoring details about contact timing and duration in school contact networks on outbreak size modelling can vary across different schools. PMID:26063821

The Future of Small- and Medium-Sized Communities in the Prairie Region.

ERIC Educational Resources Information Center

Wellar, Barry S., Ed.

Four papers are featured. The first is a statistical overview and analysis of past, present and future happenings to small communities in the Region; it focuses on two indicators: (1) population growth or declining community class size and, (2) the changing distribution of commercial outlets by community class size. The other three papers report…

Channel catfish Ictalurus punctatus size and feed conversion ratio

USDA-ARS?s Scientific Manuscript database

Channel catfish, Ictalurus punctatus, of five size-classes were stocked into 20, 0.04-ha earthen ponds at a rate of 14,826 fish/ha. Mean initial weights for each size-class were 0.232, 0.458, 0.678, 0.911, and 1.10 kg/fish. Four ponds were randomly allotted to each treatment. A commercial 28% protei...

Impact of an 8-Month Trial Using Height-Adjustable Desks on Children’s Classroom Sitting Patterns and Markers of Cardio-Metabolic and Musculoskeletal Health

PubMed Central

Contardo Ayala, Ana María; Salmon, Jo; Timperio, Anna; Sudholz, Bronwyn; Ridgers, Nicola D.; Sethi, Parneet; Dunstan, David W.

2016-01-01

During school hours, children can sit for prolonged and unbroken periods of time. This study investigated the impact of an 8-month classroom-based intervention focusing on reducing and breaking-up sitting time on children’s cardio-metabolic risk factors (i.e., body mass index, waist circumference, blood pressure) and perceptions of musculoskeletal discomfort. Two Year-6 classes (24 students per class) in one primary school were assigned to either an intervention or control classroom. The intervention classroom was equipped with height-adjustable desks and the teacher was instructed in the delivery of pedagogical strategies to reduce and break-up sitting in class. The control classroom followed standard practice using traditional furniture. At baseline, and after 8-months, time spent sitting, standing, stepping, and sitting-bouts (occasions of continuous sitting) as well as the frequency of sit-to-stand transitions were obtained from activPAL inclinometers and the time spent in light-intensity physical activity was obtained from ActiGraph accelerometers. Demographics and musculoskeletal characteristics were obtained from a self-report survey. Hierarchical linear mixed models found that during class-time, children’s overall time spent sitting in long bouts (>10 min) were lower and the number of sit-to-stand transitions were higher in the intervention group compared to the control group, while no changes were observed for musculoskeletal pain/discomfort. No significant intervention effects were found for the anthropometrics measures and blood pressure. Height-adjustable desks and pedagogical strategies to reduce/break-up sitting can positively modify classroom sitting patterns in children. Longer interventions, larger and varied sample size may be needed to show health impacts; however, these desks did not increase musculoskeletal pain/discomfort. PMID:27973414

Drought survival and reproduction impose contrasting selection pressures on maximum body size and sexual size dimorphism in a snake, Seminatrix pygaea.

PubMed

Winne, Christopher T; Willson, John D; Whitfield Gibbons, J

2010-04-01

The causes and consequences of body size and sexual size dimorphism (SSD) have been central questions in evolutionary ecology. Two, often opposing selective forces are suspected to act on body size in animals: survival selection and reproductive (fecundity and sexual) selection. We have recently identified a system where a small aquatic snake species (Seminatrix pygaea) is capable of surviving severe droughts by aestivating within dried, isolated wetlands. We tested the hypothesis that the lack of aquatic prey during severe droughts would impose significant survivorship pressures on S. pygaea, and that the largest individuals, particularly females, would be most adversely affected by resource limitation. Our findings suggest that both sexes experience selection against large body size during severe drought when prey resources are limited, as nearly all S. pygaea are absent from the largest size classes and maximum body size and SSD are dramatically reduced following drought. Conversely, strong positive correlations between maternal body size and reproductive success in S. pygaea suggest that females experience fecundity selection for large size during non-drought years. Collectively, our study emphasizes the dynamic interplay between selection pressures that act on body size and supports theoretical predictions about the relationship between body size and survivorship in ectotherms under conditions of resource limitation.

Birth order, family size, and intelligence.

PubMed

Belmont, L; Marolla, F A

1973-12-14

The relation of birth order and family size to intellectual performance, as measured by the Raven Progressive Matrices, was examined among nearly all of 400,000 19-year-old males born in the Netherlands in 1944 through 1947. It was found that birth order and family size had independent effects on intellectual performance. Effects of family size were not present in all social classes, but effects of birth order were consistent across social class.

Size-Class Effect Contributes to Tree Species Assembly through Influencing Dispersal in Tropical Forests

PubMed Central

Hu, Yue-Hua; Kitching, Roger L.; Lan, Guo-Yu; Zhang, Jiao-Lin; Sha, Li-Qing; Cao, Min

2014-01-01

We have investigated the processes of community assembly using size classes of trees. Specifically our work examined (1) whether point process models incorporating an effect of size-class produce more realistic summary outcomes than do models without this effect; (2) which of three selected models incorporating, respectively environmental effects, dispersal and the joint-effect of both of these, is most useful in explaining species-area relationships (SARs) and point dispersion patterns. For this evaluation we used tree species data from the 50-ha forest dynamics plot in Barro Colorado Island, Panama and the comparable 20 ha plot at Bubeng, Southwest China. Our results demonstrated that incorporating an size-class effect dramatically improved the SAR estimation at both the plots when the dispersal only model was used. The joint effect model produced similar improvement but only for the 50-ha plot in Panama. The point patterns results were not improved by incorporation of size-class effects using any of the three models. Our results indicate that dispersal is likely to be a key process determining both SARs and point patterns. The environment-only model and joint-effects model were effective at the species level and the community level, respectively. We conclude that it is critical to use multiple summary characteristics when modelling spatial patterns at the species and community levels if a comprehensive understanding of the ecological processes that shape species’ distributions is sought; without this results may have inherent biases. By influencing dispersal, the effect of size-class contributes to species assembly and enhances our understanding of species coexistence. PMID:25251538

A Fast Reduced Kernel Extreme Learning Machine.

PubMed

Deng, Wan-Yu; Ong, Yew-Soon; Zheng, Qing-Hua

2016-04-01

In this paper, we present a fast and accurate kernel-based supervised algorithm referred to as the Reduced Kernel Extreme Learning Machine (RKELM). In contrast to the work on Support Vector Machine (SVM) or Least Square SVM (LS-SVM), which identifies the support vectors or weight vectors iteratively, the proposed RKELM randomly selects a subset of the available data samples as support vectors (or mapping samples). By avoiding the iterative steps of SVM, significant cost savings in the training process can be readily attained, especially on Big datasets. RKELM is established based on the rigorous proof of universal learning involving reduced kernel-based SLFN. In particular, we prove that RKELM can approximate any nonlinear functions accurately under the condition of support vectors sufficiency. Experimental results on a wide variety of real world small instance size and large instance size applications in the context of binary classification, multi-class problem and regression are then reported to show that RKELM can perform at competitive level of generalized performance as the SVM/LS-SVM at only a fraction of the computational effort incurred. Copyright © 2015 Elsevier Ltd. All rights reserved.

Physical Control of Biological Productivity Off the Coast of Peru During the 1997-1998 El Nino

NASA Technical Reports Server (NTRS)

Carr, Mary-Elena

1999-01-01

Satellite observations and an ecosystem model are used to understand the variability in the planktonic ecosystem off Peru for the period January 1996 to May 1998. The objective of this study is to quantify the changes in the ecosystem components, carbon pathways, and available food for small pelagic fish that occur associated with the change in physical forcing due to El Nino. Two periods are distinguished based on the observed sea level anomaly: a La Nina (LaN) period (1996) in which sea level was below normal and El Nino (EN), the average conditions for December 1997, in which the sea level was anomalously high. There are three phytoplankton size classes (pico-, nano-, and net-phytoplankton) which compete for nutrients and are eaten by three zooplankton size classes. The ecosystem model is forced by alongshore wind speed measured by the NASA Scatterometer (NSCAT) and the European Remote-sensing Satellites (ERS-1 and ERS-2). Larger, slower growing organisms are more sensitive to physical disturbance than smaller organisms (Carr, 1998]. In the present simulation as well, the primary effect of the El Nino (reduced nutrient supply, and increased temperature) is to reduce the biomass of large cells (netphytoplankton) and consequently of the zooplankton that rely on large cells as food source. EN conditions are accompanied by a rearrangement of carbon pathways: comparable uptake goes into reduced biomass accumulation, increased losses to respiration, reduced carbon export, and much reduced carbon available to fish. The star indicates the remotely sensed biomass (assuming a constant carbon to chlorophyll ratio of 60) as measured by the Ocean Color and Temperature Sensor (Nov.-Dec. 1996) and the Sea-viewing Wide Field-of-view Sensor (Dec. 1997). The model, which assumes no light limitation, overestimates total phytoplankton biomass. Additional Information is contained in the original.

Voices from the Field: The Perceptions of Teachers and Principals on the Class Size Reduction Program in a Large Urban School District.

ERIC Educational Resources Information Center

Munoz, Marco A.; Portes, Pedro R.

A class size reduction (CSR) program was implemented in a large low-performing urban elementary school district. The CSR program helps schools improve student learning by hiring additional teachers so that children in the early elementary grades can attend smaller classes. This study used a participant-oriented evaluation model to examine the…

Spatial and temporal consumption dynamics of trout in catch-and-release areas in Arkansas tailwaters

USGS Publications Warehouse

Flinders, John M.; Magoulick, Daniel D.

2017-01-01

Restrictive angling regulations in tailwater trout fisheries may be unsuccessful if food availability limits energy for fish to grow. We examined spatial and temporal variation in energy intake and growth in populations of Brown Trout Salmo trutta and Rainbow Trout Oncorhynchus mykiss within three catch-and-release (C-R) areas in Arkansas tailwaters to evaluate food availability compared with consumption. Based on bioenergetic simulations, Rainbow Trout fed at submaintenance levels in both size-classes (≤400 mm TL, >400 mm TL) throughout most seasons. A particular bottleneck in food availability occurred in the winter for Rainbow Trout when the daily ration was substantially below the minimum required for maintenance, despite reduced metabolic costs associated with lower water temperatures. Rainbow Trout growth rates followed a similar pattern to consumption with negative growth rates during the winter periods. All three size-classes (<250 mm TL, 250–400 mm TL, >400 mm TL) of Brown Trout experienced high growth rates and limited temporal bottlenecks in food availability. We observed higher mean densities for Rainbow Trout (47–342 fish/ha) than for Brown Trout (3–84 fish/ha) in all C-R areas. Lower densities of Brown Trout coupled with an ontogenetic shift towards piscivory may have allowed for higher growth rates and sufficient consumption rates to meet energetic demands. Brown Trout at current densities were more effective in maintaining adequate growth rates and larger sizes in C-R areas than were Rainbow Trout. Bioenergetic simulations suggest that reducing stocking levels of Rainbow Trout in the tailwaters may be necessary in order to achieve increased catch rates of larger trout in the C-R areas.

Consumptive and nonconsumptive effects of cannibalism in fluctuating age-structured populations.

PubMed

Wissinger, Scott A; Whiteman, Howard H; Denoël, Mathieu; Mumford, Miranda L; Aubee, Catherine B

2010-02-01

Theory and empirical studies suggest that cannibalism in age-structured populations can regulate recruitment depending on the intensity of intraspecific competition between cannibals and victims and the nature of the cannibalism window, i.e., which size classes interact as cannibals and victims. Here we report on a series of experiments that quantify that window for age-structured populations of salamander larvae and paedomorphic adults. We determined body size limits on cannibalism in microcosms and then the consumptive and nonconsumptive (injuries, foraging and activity, diet, growth) effects on victims in mesocosms with seminatural levels of habitat complexity and alternative prey. We found that cannibalism by the largest size classes (paedomorphs and > or = age 3+ yr larvae) occurs mainly on young-of-the-year (YOY) victims. Surviving YOY and other small larvae had increased injuries, reduced activity levels, and reduced growth rates in the presence of cannibals. Data on YOY survival in an experiment in which we manipulated the density of paedomorphs combined with historical data on the number of cannibals in natural populations indicate that dominant cohorts of paedomorphs can cause observed recruitment failures. Dietary data indicate that ontogenetic shifts in diet should preclude strong intraspecific competition between YOY and cannibals in this species. Thus our results are consistent with previous empirical and theoretical work that suggests that recruitment regulation by cannibalism is most likely when YOY are vulnerable to cannibalism but have low dietary overlap with cannibals. Understanding the role of cannibalism in regulating recruitment in salamander populations is timely, given the widespread occurrences of amphibian decline. Previous studies have focused on extrinsic (including anthropogenic) factors that affect amphibian population dynamics, whereas the data presented here combined with long-term field observations suggest the potential for intrinsically driven population cycles.

Coral population dynamics across consecutive mass mortality events.

PubMed

Riegl, Bernhard; Purkis, Sam

2015-11-01

Annual coral mortality events due to increased atmospheric heat may occur regularly from the middle of the century and are considered apocalyptic for coral reefs. In the Arabian/Persian Gulf, this situation has already occurred and population dynamics of four widespread corals (Acropora downingi, Porites harrisoni, Dipsastrea pallida, Cyphastrea micropthalma) were examined across the first-ever occurrence of four back-to-back mass mortality events (2009-2012). Mortality was driven by diseases in 2009, bleaching and subsequent diseases in 2010/2011/2012. 2009 reduced P. harrisoni cover and size, the other events increasingly reduced overall cover (2009: -10%; 2010: -20%; 2011: -20%; 2012: -15%) and affected all examined species. Regeneration was only observed after the first disturbance. P. harrisoni and A. downingi severely declined from 2010 due to bleaching and subsequent white syndromes, while D. pallida and P. daedalea declined from 2011 due to bleaching and black-band disease. C. microphthalma cover was not affected. In all species, most large corals were lost while fission due to partial tissue mortality bolstered small size classes. This general shrinkage led to a decrease of coral cover and a dramatic reduction of fecundity. Transition matrices for disturbed and undisturbed conditions were evaluated as Life Table Response Experiment and showed that C. microphthalma changed the least in size-class dynamics and fecundity, suggesting they were 'winners'. In an ordered 'degradation cascade', impacts decreased from the most common to the least common species, leading to step-wise removal of previously dominant species. A potentially permanent shift from high- to low-coral cover with different coral community and size structure can be expected due to the demographic dynamics resultant from the disturbances. Similarities to degradation of other Caribbean and Pacific reefs are discussed. As comparable environmental conditions and mortality patterns must be expected worldwide, demographic collapse of many other coral populations may soon be widespread. © 2015 John Wiley & Sons Ltd.

Benign prostatic hyperplasia (BPH) management in the primary care setting.

PubMed

Kapoor, Anil

2012-10-01

Benign prostate hyperplasia (BPH) occurs in up to 50% of men by age 50, and the incidence increases with age. This common clinical problem is diagnosed by history, including the International Prostate Symptom Score (IPSS) questionnaire, and physical examination by digital rectal examination (DRE). Initial management for BPH includes lifestyle modification, and smooth muscle relaxant alpha blocker therapy. Alpha blockers usually take effect quickly within 3-5 days, and have minimal side effects. Current commonly used alpha blockers include the selective alpha blockers tamsulosin (Flomax), alfusosin (Xatral), and silodosin (Rapaflo). For patients with larger prostates, the 5-alpha reductase inhibitor class (finasteride (Proscar) and dutasteride (Avodart)) work effectively to shrink prostate stroma resulting in improved voiding. The 5-ARI class of drugs, in addition to reducing prostate size, also reduce the need for future BPH-related surgery, and reduce the risk of future urinary retention. Drugs from the phosphodiesterase-5 (PDE-5) inhibitor class may now be considered for treating BPH. Once daily 5 mg tadalafil has been shown to improve BPH-related symptoms and is currently approved to treat patients with BPH. Referral to a urologist can be considered for patients with a rising prostate-specific antigen (PSA), especially while on 5-ARI, failure of urinary symptom control despite maximal medical therapy, suspicion of prostate cancer, hematuria, recurrent urinary infections, urinary retention, or renal failure. Currently the primary care physician is armed with multiple treatment options to effectively treat men with symptomatic BPH.

40 CFR 144.28 - Requirements for Class I, II, and III wells authorized by rule.

Code of Federal Regulations, 2010 CFR

2010-07-01

... proposed test or measurement to be made; (D) The amount, size, and location (by depth) of casing to be left..., internal pressure, and axial loading; (iv) Hole size; (v) Size and grade of all casing strings; and (vi... Class III wells the owner or operator shall provide to the Director a qualitative analysis and ranges in...

Determining stocking, forest type and stand-size class from forest inventory data

Treesearch

Mark H. Hansen; Jerold T. Hahn

1992-01-01

This paper describes the procedures used by North Central Forest Experiment Station's Forest Inventory and Analysis Work Unit (NCFIA) in determining stocking, forest type, and stand-size class. The stocking procedure assigns a portion of the stocking to individual trees measured on NCFIA 10-point field plots. Stand size and forest type are determined as functions...

Shape Comparison Between 0.4–2.0 and 20–60 lm Cement Particles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holzer, L.; Flatt, R; Erdogan, S

Portland cement powder, ground from much larger clinker particles, has a particle size distribution from about 0.1 to 100 {micro}m. An important question is then: does particle shape depend on particle size? For the same cement, X-ray computed tomography has been used to examine the 3-D shape of particles in the 20-60 {micro}m sieve range, and focused ion beam nanotomography has been used to examine the 3-D shape of cement particles found in the 0.4-2.0 {micro}m sieve range. By comparing various kinds of computed particle shape data for each size class, the conclusion is made that, within experimental uncertainty, bothmore » size classes are prolate, but the smaller size class particles, 0.4-2.0 {micro}m, tend to be somewhat more prolate than the 20-60 {micro}m size class. The practical effect of this shape difference on the set-point was assessed using the Virtual Cement and Concrete Testing Laboratory to simulate the hydration of five cement powders. Results indicate that nonspherical aspect ratio is more important in determining the set-point than are the actual shape details.« less

Back to the Future: Building resilience in Colorado Front Range forests using research findings and a new guide for restoration of ponderosa and dry-mixed conifer landscapes

Treesearch

Sue Miller; Rob Addington; Greg Aplet; Mike Battaglia; Tony Cheng; Jonas Feinstein; Jeff Underhill

2018-01-01

Historically, the ponderosa and dry mixed-conifer forests of the Colorado Front Range were more open and grassy, and trees of all size classes were found in a grouped arrangement with sizable openings between the clumps. As a legacy of fire suppression, today’s forests are denser, with smaller trees. Proactive restoration of this forest type will help to reduce fuel...

Nanoengineered particles for enhanced intra-articular retention and delivery of proteins.

PubMed

Singh, Ankur; Agarwal, Rachit; Diaz-Ruiz, Carlos A; Willett, Nick J; Wang, Peiyi; Lee, L Andrew; Wang, Qian; Guldberg, Robert E; García, Andrés J

2014-10-01

Localized intra-articular delivery of anti-inflammatory proteins can reduce inflammation in osteoarthritis but poses a challenge because of raid clearance within few hours of injection. A new class of polymer is developed that forms self-assembled nanoparticles ranging from 300 to 900 nm and demonstrates particle size dependent prolonged retention in intra-articular joint spaces compared to bolus protein over a period of 14 d. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Prevalence of Sarcopenic Obesity in Adults with Class II/III Obesity Using Different Diagnostic Criteria.

PubMed

Johnson Stoklossa, Carlene A; Sharma, Arya M; Forhan, Mary; Siervo, Mario; Padwal, Raj S; Prado, Carla M

2017-01-01

Background/Objective . Sarcopenic obesity (SO) is a hidden condition of reduced lean soft tissue (LST) in context of excess adiposity. SO is most commonly reported in older adults and both its risk and prevalence increase with age. A variety of body composition indices and cut points have been used to define this condition, leading to conflicting prevalence and risk prediction. Here, we investigate variability in the prevalence of SO in an adult sample of individuals with class II/III obesity (BMI ≥ 35 kg/m 2 ) using different diagnostic criteria. Methods . SO definitions were identified from a literature review of studies using dual-energy X-ray absorptiometry (DXA) to assess LST. Demographics, anthropometrics, and body composition (by DXA) were measured in n = 120, 86% female (46.9 ± 11.1 years). Results . LST was extremely variable in individuals, even with similar body sizes, and observed across the age spectrum. The prevalence of SO ranged from 0 to 84.5% in females and 0 to 100% in males, depending upon the definition applied, with higher prevalence among definitions accounting for measures of body size or fat mass. Conclusion . SO is present, yet variable, in adults with class II/III obesity. Accounting for body mass or fat mass may identify a higher number of individuals with SO, although risk prediction remains to be studied.

Measurement of tree canopy architecture

NASA Technical Reports Server (NTRS)

Martens, S. N.; Ustin, S. L.; Norman, J. M.

1991-01-01

The lack of accurate extensive geometric data on tree canopies has retarded development and validation of radiative transfer models. A stratified sampling method was devised to measure the three-dimensional geometry of 16 walnut trees which had received irrigation treatments of either 100 or 33 per cent of evapotranspirational (ET) demand for the previous two years. Graphic reconstructions of the three-dimensional geometry were verified by 58 independent measurements. The distributions of stem- and leaf-size classes, lengths, and angle classes were determined and used to calculate leaf area index (LAI), stem area, and biomass. Reduced irrigation trees have lower biomass of stems, leaves and fruit, lower LAI, steeper leaf angles and altered biomass allocation to large stems. These data can be used in ecological models that link canopy processes with remotely sensed measurements.

ePix: a class of architectures for second generation LCLS cameras

DOE PAGES

Dragone, A.; Caragiulo, P.; Markovic, B.; ...

2014-03-31

ePix is a novel class of ASIC architectures, based on a common platform, optimized to build modular scalable detectors for LCLS. The platform architecture is composed of a random access analog matrix of pixel with global shutter, fast parallel column readout, and dedicated sigma-delta analog-to-digital converters per column. It also implements a dedicated control interface and all the required support electronics to perform configuration, calibration and readout of the matrix. Based on this platform a class of front-end ASICs and several camera modules, meeting different requirements, can be developed by designing specific pixel architectures. This approach reduces development time andmore » expands the possibility of integration of detector modules with different size, shape or functionality in the same camera. The ePix platform is currently under development together with the first two integrating pixel architectures: ePix100 dedicated to ultra low noise applications and ePix10k for high dynamic range applications.« less

Association of a behaviorally based high school health education curriculum with increased exercise.

PubMed

Annesi, James J; Trinity, John; Mareno, Nicole; Walsh, Stephanie M

2015-06-01

Increasing exercise in children and adolescents through academic classes is an understudied area. Potential benefits include associated improvements in health, psychosocial, and quality-of-life factors. A sample of 98 students (M(age) = 14.3) from high school health education classes received six, 40-min lessons incorporating cognitive-behavioral methods to increase exercise over 6 weeks. Significant within-group improvements in exercise, mood, and body satisfaction were found, with slightly larger effect sizes identified for the boys. Increase in exercise was significantly associated with reduced mood distress (β = -.17, p < .001). For the girls only, change in body satisfaction significantly mediated that relationship, and a reciprocal relationship between changes in mood and body satisfaction was also identified. Incorporation of lessons emphasizing goal setting and self-regulation within high school health education classes may foster increased exercise and associated improvements in mood and body satisfaction. For girls, the positive effects may reinforce one another. © The Author(s) 2014.

Variability in Phytoplankton Morphology and Macromolecular Composition With Nutrient Starvation and The Implications for Oceanic Elemental Stoichiometry

NASA Astrophysics Data System (ADS)

Liefer, J. D.; Benner, I.; Brown, C. M.; Garg, A.; Fiset, C.; Irwin, A. J.; Follows, M. J.; Finkel, Z.

2016-02-01

Trait based modeling efforts are an important tool for predicting the distribution of phytoplankton communities in the ocean and their interaction with elemental stoichiometry. The elemental stoichiometry of phytoplankton is based on their macromolecular composition. Many phytoplankton species accumulate C-rich storage products (carbohydrates and lipids) and reduce N and P-rich functional components (proteins and nucleic acids) upon N- or P-starvation. Reconciling global patterns in C:N:P stoichiometry and phytoplankton community structure and succession requires a better understanding of how phytoplankton macromolecular composition varies across taxa, size class, and growth conditions. We examined changes in cell size and composition from exponential growth to nitrogen starvation in four common phytoplankton species representing two size classes each of chlorophytes and diatoms. Variation in cell size, cell mass, and length of stationary growth phase appeared to be size dependent. The larger species of chlorophyte and diatom had a significant increase in cell mass and cell size with N-starvation and showed no significant change in cell density after starvation for 5-7 days. The smaller size species of both phyla showed no significant change in cell size or mass upon N-starvation and a consistent decline in cell density 1-2 days after peak densities were reached. All species had a similar significant increase in C quota, but changes in N quota and C:N were more variable and species-specific. We also present changes in macromolecular composition and C, N, and P-allocation due to N-starvation and their implications for elemental stoichiometry under natural conditions. These results are compared to field observations of C:N:P stoichiometry and phytoplankton community structure to examine the physiological plasticity that may underlie global oceanic C:N:P variability and demonstrate the importance of this plasticity in trait based models.

Dispersion and sampling of adult Dermacentor andersoni in rangeland in Western North America.

PubMed

Rochon, K; Scoles, G A; Lysyk, T J

2012-03-01

A fixed precision sampling plan was developed for off-host populations of adult Rocky Mountain wood tick, Dermacentor andersoni (Stiles) based on data collected by dragging at 13 locations in Alberta, Canada; Washington; and Oregon. In total, 222 site-date combinations were sampled. Each site-date combination was considered a sample, and each sample ranged in size from 86 to 250 10 m2 quadrats. Analysis of simulated quadrats ranging in size from 10 to 50 m2 indicated that the most precise sample unit was the 10 m2 quadrat. Samples taken when abundance < 0.04 ticks per 10 m2 were more likely to not depart significantly from statistical randomness than samples taken when abundance was greater. Data were grouped into ten abundance classes and assessed for fit to the Poisson and negative binomial distributions. The Poisson distribution fit only data in abundance classes < 0.02 ticks per 10 m2, while the negative binomial distribution fit data from all abundance classes. A negative binomial distribution with common k = 0.3742 fit data in eight of the 10 abundance classes. Both the Taylor and Iwao mean-variance relationships were fit and used to predict sample sizes for a fixed level of precision. Sample sizes predicted using the Taylor model tended to underestimate actual sample sizes, while sample sizes estimated using the Iwao model tended to overestimate actual sample sizes. Using a negative binomial with common k provided estimates of required sample sizes closest to empirically calculated sample sizes.

A mechanistic assessment of seasonal microhabitat selection by drift-feeding rainbow trout Oncorhynchus mykiss in a southwestern headwater stream

USGS Publications Warehouse

Kalb, Bradley W.; Huntsman, Brock M.; Caldwell, Colleen A.; Bozek, Michael A.

2018-01-01

The positioning of fishes within a riverscape is dependent on the proximity of complementary habitats. In this study, foraging and non-foraging habitat were quantified monthly over an entire year for a rainbow trout (Oncorhynchus mykiss) population in an isolated, headwater stream in southcentral New Mexico. The stream follows a seasonal thermal and hydrologic pattern typical for a Southwestern stream and was deemed suitable for re-introduction of the native and close relative, Rio Grande cutthroat trout (O. clarkii virginalis). However, uncertainty associated with limited habitat needed to be resolved if repatriation of the native fish was to be successful. Habitat was evaluated using resource selection functions with a mechanistic drift-foraging model to explain trout distributions. Macroinvertebrate drift was strongly season- and temperature-dependent (lower in winter and spring, higher in summer and fall). Models identified stream depth as the most limiting factor for habitat selection across seasons and size-classes. Additionally, positions closer to cover were selected during the winter by smaller size-classes (0, 1, 2), while net energy intake was important during the spring for most size-classes (0, 1, 2, 3). Drift-foraging models identified that 81% of observed trout selected positions that could meet maintenance levels throughout the year. Moreover, 40% of selected habitats could sustain maximum growth. Stream positions occupied by rainbow trout were more energetically profitable than random sites regardless of season or size-class. Larger size-classes (3, 4+) were energetically more limited throughout the year than were smaller size-classes. This research suggests that habitat in the form of deep pools is of paramount importance for rainbow trout or native cutthroat trout.

Size Class Distribution of Quercus engelmannii (Engelmann Oak) on the Santa Rosa Plateau, Riverside County, California

Treesearch

Earl W. Lathrop; Chris Osborne; Anna Rochester; Kevin Yeung; Samuel Soret; Rochelle Hopper

1991-01-01

Size class distribution of Quercus engelmannii (Engelmann oak) on the Santa Rosa Plateau was studied to understand whether current recruitment of young oaks is sufficient to maintain the population in spite of high natural mortality and impacts of development in some portions of the plateau woodland. Sapling-size oaks (1-10 cm dbh) made up 5.56 pct...

POM Pulses: Characterizing the Physical and Chemical Properties of Particulate Organic Matter (POM) Mobilized by Large Storm Events and its Influence on Receiving Fluvial Systems

NASA Astrophysics Data System (ADS)

Johnson, E. R.; Rowland, R. D.; Protokowicz, J.; Inamdar, S. P.; Kan, J.; Vargas, R.

2016-12-01

Extreme storm events have tremendous erosive energy which is capable of mobilizing vast amounts of material from watershed sources into fluvial systems. This complex mixture of sediment and particulate organic matter (POM) is a nutrient source, and has the potential to impact downstream water quality. The impact of POM on receiving aquatic systems can vary not only by the total amount exported but also by the various sources involved and the particle sizes of POM. This study examines the composition of POM in potential sources and within-event POM by: (1) determining the amount and quality of dissolved organic matter (DOM) that can be leached from coarse, medium and fine particle classes; (2) assessing the C and N content and isotopic character of within-event POM; and (3) coupling physical and chemical properties to evaluate storm event POM influence on stream water. Storm event POM samples and source sediments were collected from a forested headwater catchment (second order stream) in the Piedmont region of Maryland. Samples were sieved into three particle classes - coarse (2mm-1mm), medium (1mm-250µm) and fine (<250µm). Extractions were performed for three particle class sizes and the resulting fluorescent organic matter was analyzed. Carbon (C) and Nitrogen (N) amount, C:N ratio, and isotopic analysis of 13C and 15N were performed on solid state event and source material. Future work will include examination of microbial communities associated with POM particle size classes. Physical size class separation of within-event POM exhibited differences in C:N ratios, δ15N composition, and extracted DOM lability. Smaller size classes exhibited lower C:N ratios, more enriched δ15N and more recalcitrant properties in leached DOM. Source material had varying C:N ratios and contributions to leached DOM. These results indicate that both source and size class strongly influence the POM contribution to fluvial systems during large storm events.

The relative efficiency of modular and non-modular networks of different size

PubMed Central

Tosh, Colin R.; McNally, Luke

2015-01-01

Most biological networks are modular but previous work with small model networks has indicated that modularity does not necessarily lead to increased functional efficiency. Most biological networks are large, however, and here we examine the relative functional efficiency of modular and non-modular neural networks at a range of sizes. We conduct a detailed analysis of efficiency in networks of two size classes: ‘small’ and ‘large’, and a less detailed analysis across a range of network sizes. The former analysis reveals that while the modular network is less efficient than one of the two non-modular networks considered when networks are small, it is usually equally or more efficient than both non-modular networks when networks are large. The latter analysis shows that in networks of small to intermediate size, modular networks are much more efficient that non-modular networks of the same (low) connective density. If connective density must be kept low to reduce energy needs for example, this could promote modularity. We have shown how relative functionality/performance scales with network size, but the precise nature of evolutionary relationship between network size and prevalence of modularity will depend on the costs of connectivity. PMID:25631996

49 CFR 175.704 - Plutonium shipments.

Code of Federal Regulations, 2010 CFR

2010-10-01

... lower cargo compartment in the aft-most location that is possible for cargo of its size and weight, and... aboard an aircraft carrying other cargo required to bear any of the following labels: Class 1 (all Divisions), Class 2 (all Divisions), Class 3, Class 4 (all Divisions), Class 5 (all Divisions), or Class 8...

Automated thematic mapping and change detection of ERTS-A images

NASA Technical Reports Server (NTRS)

Gramenopoulos, N. (Principal Investigator)

1975-01-01

The author has identified the following significant results. In the first part of the investigation, spatial and spectral features were developed which were employed to automatically recognize terrain features through a clustering algorithm. In this part of the investigation, the size of the cell which is the number of digital picture elements used for computing the spatial and spectral features was varied. It was determined that the accuracy of terrain recognition decreases slowly as the cell size is reduced and coincides with increased cluster diffuseness. It was also proven that a cell size of 17 x 17 pixels when used with the clustering algorithm results in high recognition rates for major terrain classes. ERTS-1 data from five diverse geographic regions of the United States were processed through the clustering algorithm with 17 x 17 pixel cells. Simple land use maps were produced and the average terrain recognition accuracy was 82 percent.

Harvesting, predation and competition effects on a red coral population

NASA Astrophysics Data System (ADS)

Abbiati, M.; Buffoni, G.; Caforio, G.; Di Cola, G.; Santangelo, G.

A Corallium rubrum population, dwelling in the Ligurian Sea, has been under observation since 1987. Biometric descriptors of colonies (base diameter, weight, number of polyps, number of growth rings) have been recorded and correlated. The population size structure was obtained by distributing the colonies into diameter classes, each size class representing the average annual increment of diameter growth. The population was divided into ten classes, including a recruitment class. This size structure showed a fairly regular trend in the first four classes. The irregularity of survival in the older classes agreed with field observations on harvesting and predation. Demographic parameters such as survival, growth plasticity and natality coefficients were estimated from the experimental data. On this basis a discrete nonlinear model was implemented. The model is based on a kind of density-dependent Leslie matrix, where the feedback term only occurs in survival of the first class; the recruitment function is assumed to be dependent on the total biomass and related to inhibiting effects due to competitive interactions. Stability analysis was applied to steady-state solutions. Numerical simulations of population evolution were carried out under different conditions. The dynamics of settlement and the effects of disturbances such as harvesting, predation and environmental variability were studied.

Small benthic size classes along the N.W. European Continental Margin: spatial and temporal variability in activity and biomass

NASA Astrophysics Data System (ADS)

Pfannkuche, O.; Soltwedel, T.

1998-12-01

In the context of the European OMEX Programme this investigation focused on gradients in the biomass and activity of the small benthic size spectrum along a transect across the Goban Spur from the outer Celtic Sea into Porcupine Abyssal Plain. The effects of food pulses (seasonal, episodic) on this part of the benthic size spectrum were investigated. Sediments sampled during eight expeditions at different seasons covering a range from 200 m to 4800 m water depth were assayed with biochemical bulk measurements: determinations of chloroplastic pigment equivalents (CPE), the sum of chlorophyll a and its breakdown products, provide information concerning the input of phytodetrital matter to the seafloor; phospholipids were analyzed to estimate the total biomass of small benthic organisms (including bacteria, fungi, flagellata, protozoa and small metazoan meiofauna). A new term `small size class biomass' (SSCB) is introduced for the biomass of the smallest size classes of sediment-inhabiting organisms; the reduction of fluorescein-di-acetate (FDA) was determined to evaluate the potential activity of ester-cleaving bacterial exoenzymes in the sediment samples. At all stations benthic biomass was predominantly composed of the small size spectrum (90% on the shelf; 97-98% in the bathyal and abyssal parts of the transect). Small size class biomass (integrated over a 10 cm sediment column) ranged from 8 g C m -2 on the shelf to 2.1 g C m -2 on the adjacent Porcupine Abyssal Plain, exponentially decreasing with increasing water depth. However, a correlation between water depth and SSCB, macrofauna biomass as well as metazoan meiofauna biomass exhibited a significantly flatter slope for the small size classes in comparison to the larger organisms. CPE values indicated a pronounced seasonal cycle on the shelf and upper slope with twin peaks of phytodetrital deposition in mid spring and late summer. The deeper stations seem to receive a single annual flux maximum in late summer. SSCB and heterotrophic activity are significantly correlated to the amount of sediment-bound pigments. Seasonality in pigment concentrations is clearly followed by SSCB and activity. In contrast to macro- and megafauna which integrate over larger periods (months/years), the small benthic size classes, namely bacteria and foraminifera, proved to be the most reactive potential of the benthic communities to any perturbations on short time scales (days/weeks). The small size classes, therefore, occupy a key role in early diagenetic processes.

Impact of interactive school-based media literacy lessons for reducing internalization of media ideals in young adolescent girls and boys.

PubMed

Wilksch, Simon M; Tiggemann, Marika; Wade, Tracey D

2006-07-01

The primary objective of the current study was to examine the efficacy of single media literacy lessons in reducing media internalization in young adolescents. Eleven classes of 237 students (100 girls and 137 boys; mean age = 13.79 years, SD = .42) randomly received 1 of 6 lessons. Eating disorder risk factors were assessed at baseline, and the Sociocultural Attitudes Towards Appearance Questionnaire-3 (SATAQ-3) was used to assess media internalization postintervention. At postintervention, boys had significantly lower SATAQ-3 scores on 4 of the 5 subscales (effect sizes = .42-.71), whereas girls had significantly lower scores on 1 subscale (effect size = .54). Higher baseline levels of dietary restraint, magazines bought/read, and perceived sociocultural pressure predicted smaller reductions in boys' scores, whereas depression predicted smaller reductions in girls' scores. The current study provides support that boys be included in eating disorder prevention programs and that media literacy may represent a promising prevention approach.

Characterization and classification of zebrafish brain morphology mutants

PubMed Central

Lowery, Laura Anne; De Rienzo, Gianluca; Gutzman, Jennifer H.; Sive, Hazel

2010-01-01

The mechanisms by which the vertebrate brain achieves its three-dimensional structure are clearly complex, requiring the functions of many genes. Using the zebrafish as a model, we have begun to define genes required for brain morphogenesis, including brain ventricle formation, by studying 16 mutants previously identified as having embryonic brain morphology defects. We report the phenotypic characterization of these mutants at several time-points, using brain ventricle dye injection, imaging, and immunohistochemistry with neuronal markers. Most of these mutants display early phenotypes, affecting initial brain shaping, while others show later phenotypes, affecting brain ventricle expansion. In the early phenotype group, we further define four phenotypic classes and corresponding functions required for brain morphogenesis. Although we did not use known genotypes for this classification, basing it solely on phenotypes, many mutants with defects in functionally related genes clustered in a single class. In particular, class 1 mutants show midline separation defects, corresponding to epithelial junction defects; class 2 mutants show reduced brain ventricle size; class 3 mutants show midbrain-hindbrain abnormalities, corresponding to basement membrane defects; and class 4 mutants show absence of ventricle lumen inflation, corresponding to defective ion pumping. Later brain ventricle expansion requires the extracellular matrix, cardiovascular circulation, and transcription/splicing-dependent events. We suggest that these mutants define processes likely to be used during brain morphogenesis throughout the vertebrates. PMID:19051268

Lipoxygenase is involved in the control of potato tuber development.

PubMed

Kolomiets, M V; Hannapel, D J; Chen, H; Tymeson, M; Gladon, R J

2001-03-01

Plant lipoxygenases (LOXs) are a functionally diverse class of dioxygenases implicated in physiological processes such as growth, senescence, and stress-related responses. LOXs incorporate oxygen into their fatty acid substrates and produce hydroperoxide fatty acids that are precursors of jasmonic acid and related compounds. Here, we report the involvement of the tuber-associated LOXs, designated the Lox1 class, in the control of tuber growth. RNA hybridization analysis showed that the accumulation of Lox1 class transcripts was restricted to developing tubers, stolons, and roots and that mRNA accumulation correlated positively with tuber initiation and growth. In situ hybridization showed that Lox1 class transcripts accumulated in the apical and subapical regions of the newly formed tuber, specifically in the vascular tissue of the perimedullary region, the site of the most active cell growth during tuber enlargement. Suppression mutants produced by expressing antisense coding sequence of a specific tuber LOX, designated POTLX-1, exhibited a significant reduction in LOX activity in stolons and tubers. The suppression of LOX activity correlated with reduced tuber yield, decreased average tuber size, and a disruption of tuber formation. Our results indicate that the pathway initiated by the expression of the Lox1 class genes of potato is involved in the regulation of tuber enlargement.

[Pesticides use by flower companies associated with the Colombian Association of Flower Exporters].

PubMed

Varona, Marcela E; Tolosa, Jorge E; Cárdenas, Omayda; Torres, Carlos H; Pardo, Darío; Carrasquilla, Gabriel; Frumkin, Howard

2005-09-01

In Colombia, pesticide exposure has became a public health problem, as the use of these substances continues to increase. The current study accumulated information concerning pesticides used by flower companies in Bogotá and Rionegro (Antioquia) that were associated with Asociación Colombiana de Exportadores de Flores (Asocolflores) in Colombia. Eighty-four companies were stratified by geographic location and size. Company and worker information was collected, and for each company, the process of pesticide application and maintenance of the cultivated flowers was carefully observed. Univariate and bivariate, and correlation analyses were applied for data analysis. Sex of workers was 39.4% male and 60.6% female. Pesticides were grouped into 4 toxicity classes: 14.3% were class I, 14.4% class II, 52.0% class III, and 19.2% class IV. Dithiocarbamates was the group of pesticides more commonly used (11.7%). The equipment most frequently used for pesticide application was the "bomba móvil" (92.8%), and the "lanza" (92.9%). Cholinesterase activity measured by the Michel-Aldrige method was the biological marker for exposure to pesticides used in 85.9% of the companies. Recommendations for improvements in their use and for measures to further reduce exposure of workers are made.

Quantifying Grain-Size Variability of Metal Pollutants in Road-Deposited Sediments Using the Coefficient of Variation

PubMed Central

Wang, Xiaoxue; Li, Xuyong

2017-01-01

Particle grain size is an important indicator for the variability in physical characteristics and pollutants composition of road-deposited sediments (RDS). Quantitative assessment of the grain-size variability in RDS amount, metal concentration, metal load and GSFLoad is essential to elimination of the uncertainty it causes in estimation of RDS emission load and formulation of control strategies. In this study, grain-size variability was explored and quantified using the coefficient of variation (Cv) of the particle size compositions, metal concentrations, metal loads, and GSFLoad values in RDS. Several trends in grain-size variability of RDS were identified: (i) the medium class (105–450 µm) variability in terms of particle size composition, metal loads, and GSFLoad values in RDS was smaller than the fine (<105 µm) and coarse (450–2000 µm) class; (ii) The grain-size variability in terms of metal concentrations increased as the particle size increased, while the metal concentrations decreased; (iii) When compared to the Lorenz coefficient (Lc), the Cv was similarly effective at describing the grain-size variability, whereas it is simpler to calculate because it did not require the data to be pre-processed. The results of this study will facilitate identification of the uncertainty in modelling RDS caused by grain-size class variability. PMID:28788078

Ability of One-Dimensional Hairsine-Rose Erosion Model to Predict Sediment Transport over a Soil with Significant Surface Stones

NASA Astrophysics Data System (ADS)

Jomaa, S.; Barry, D. A.; Sander, G. C.; Parlange, J.-Y.; Heng, B. C. P.; Tromp-van Meerveld, H. J.

2010-05-01

Surface stones affect erosion rates by reducing raindrop-driven detachment and protecting the original soil against overland flow induced-hydraulic stress. Numerous studies have shown that the effect of surface stones on erosion depends on both the stone characteristics (e.g., size, distribution) and the soil properties. The aim of this study was (i) to quantify how the stone characteristics can affect the total sediment concentration and the concentrations of the individual size classes, (ii) to test if stones affect preferentially a particular size class within the eroded sediment and (iii) to determine whether the 1D Hairsine-Rose (H-R) erosion model can represent the experimental data. A series of laboratory experiments were conducted using the 2 m × 6 m EPFL erosion flume for a high rainfall intensity (60 mm/h) event on a gentle slope (2.2%). The flume was divided into two identical 1-m wide flumes. This separation was done to allow simultaneous replicate experiments. Experiments were conducted with different configurations and scenarios (stone coverage, size and emplacement). Three coverage proportions (20%, 40%, and 70%), two stone diameters (3-4 and 6-7 cm) and two emplacement types (topsoil and partially embedded) were tested. For each experiment, the total sediment concentration, the concentration for the individual size classes, and the flume discharge were measured. Infiltration rates were measured at different depths and locations. A high resolution laser scanner provided details of the surface change due to erosion during the experiments. This technique allowed us to quantify the spatial distribution of eroded soil and to understand better if sediment transport is 1D or rather 2D over the flumes. The one-dimensional Hairsine-Rose (H-R) erosion model was used to fit the integrated data and to provide estimates of the parameters. The ability of the 1D H-R model to predict the measured sediment concentrations in the presence of stones in the soil matrix with different configurations was tested, with reasonable results.

A population model for a long-lived, resprouting chaparral shrub: Adenostoma fasciculatum

USGS Publications Warehouse

Stohlgren, Thomas J.; Rundel, Philip W.

1986-01-01

Extensive stands of Adenostoma fasciculatum H.&A. (chamise) in the chaparral of California are periodically rejuvenated by fire. A population model based on size-specific demographic characteristics (thinning and fire-caused mortality) was developed to generate probable age distributions within size classes and survivorship curves for typical stands. The model was modified to assess the long term effects of different mortality rates on age distributions. Under observed mean mortality rates (28.7%), model output suggests some shrubs can survive more than 23 fires. A 10% increase in mortality rate by size class slightly shortened the survivorship curve, while a 10% decrease in mortality rate by size class greatly elongated the curve. This approach may be applicable to other long-lived plant species with complex life histories.

The effect of sample size and disease prevalence on supervised machine learning of narrative data.

PubMed Central

McKnight, Lawrence K.; Wilcox, Adam; Hripcsak, George

2002-01-01

This paper examines the independent effects of outcome prevalence and training sample sizes on inductive learning performance. We trained 3 inductive learning algorithms (MC4, IB, and Naïve-Bayes) on 60 simulated datasets of parsed radiology text reports labeled with 6 disease states. Data sets were constructed to define positive outcome states at 4 prevalence rates (1, 5, 10, 25, and 50%) in training set sizes of 200 and 2,000 cases. We found that the effect of outcome prevalence is significant when outcome classes drop below 10% of cases. The effect appeared independent of sample size, induction algorithm used, or class label. Work is needed to identify methods of improving classifier performance when output classes are rare. PMID:12463878

Test Operation Procedure (TOP) 01-1-010A Vehicle Test Course Severity (Surface Roughness)

DTIC Science & Technology

2017-12-12

Department of Agriculture (USDA) classifications, respectively. TABLE 10. PARTICLE SIZE CLASSES CLASS SIZE Cobble and Gravel >4.75 mm particle diameter...ABBREVIATIONS. USCS Unified Soil Classification System USDA United States Department of Agriculture UTM Universal Transverse Mercator WNS wave number

Montane conifer fuel dynamics, Yosemite National Park

USGS Publications Warehouse

van Wagtendonk, J.W.; Moore, P.E.

1997-01-01

Litter and woody fuel accumulation rates over 7 years for 7 montane Sierra Nevada conifer species, including giant sequoia, ponderosa pine, sugar pine, Jeffrey pine, incense-cedar and white fir. Data are from four sites per size class per species with four size classes each. Nonspatial, georeferenced.

Effect Sizes in Three-Level Cluster-Randomized Experiments

ERIC Educational Resources Information Center

Hedges, Larry V.

2011-01-01

Research designs involving cluster randomization are becoming increasingly important in educational and behavioral research. Many of these designs involve two levels of clustering or nesting (students within classes and classes within schools). Researchers would like to compute effect size indexes based on the standardized mean difference to…

Louisiana forests: Status and outlook

Treesearch

Paul A. Murphy

1975-01-01

Between 1964 and 1974, forest area in Louisiana declined 9 percent to 14.5 million acres. Softwood volume increased 31 percent to 9 billion cubic feet, and hardwood declined 7 percent to 7.7 billion. All softwood size classes had increases in volume, and all hardwood size classes had decreases.

Migration Patterns, Densities, and Growth of Neritina punctulata Snails in Rio Espiritu Santo and Rio Mameyes, Northeastern Puerto Rico.

Treesearch

MARK PYRON; ALAN P. COVICH

2003-01-01

Snail size-frequency distributions in Rios Espiritu Santo and Mameyes, which drain the Luquillo Experimental Forest, Puerto Rico, showed that Neritina punctulata with shell lengths greater than 30 mm were the most abundant size class at upstream sites. The highest densities for all size classes were at the downstream sites. Growth rates were 0.015 mm/day for a large...

Capitalizing on Small Class Size. ERIC Digest Number 136.

ERIC Educational Resources Information Center

O'Connell, Jessica; Smith, Stuart C.

This Digest examines school districts' efforts to reap the greatest benefit from smaller classes. Although the report discusses teaching strategies that are most effective in small classes, research has shown that teachers do not significantly change their teaching practices when they move from larger to smaller classes. Smaller classes mean…

Phosphorus content as a function of soil aggregate size and paddy cultivation in highly weathered soils.

PubMed

Li, Baozhen; Ge, Tida; Xiao, Heai; Zhu, Zhenke; Li, Yong; Shibistova, Olga; Liu, Shoulong; Wu, Jinshui; Inubushi, Kazuyuki; Guggenberger, Georg

2016-04-01

Red soils are the major land resource in subtropical and tropical areas and are characterized by low phosphorus (P) availability. To assess the availability of P for plants and the potential stability of P in soil, two pairs of subtropical red soil samples from a paddy field and an adjacent uncultivated upland were collected from Hunan Province, China. Analysis of total P and Olsen P and sequential extraction was used to determine the inorganic and organic P fractions in different aggregate size classes. Our results showed that the soil under paddy cultivation had lower proportions of small aggregates and higher proportions of large aggregates than those from the uncultivated upland soil. The portion of >2-mm-sized aggregates increased by 31 and 20 % at Taoyuan and Guiyang, respectively. The total P and Olsen P contents were 50-150 and 50-300 % higher, respectively, in the paddy soil than those in the upland soil. Higher inorganic and organic P fractions tended to be enriched in both the smallest and largest aggregate size classes compared to the middle size class (0.02-0.2 mm). Furthermore, the proportion of P fractions was higher in smaller aggregate sizes (<2 mm) than in the higher aggregate sizes (>2 mm). In conclusion, soils under paddy cultivation displayed improved soil aggregate structure, altered distribution patterns of P fractions in different aggregate size classes, and to some extent had enhanced labile P pools.

A priori evaluation of two-stage cluster sampling for accuracy assessment of large-area land-cover maps

USGS Publications Warehouse

Wickham, J.D.; Stehman, S.V.; Smith, J.H.; Wade, T.G.; Yang, L.

2004-01-01

Two-stage cluster sampling reduces the cost of collecting accuracy assessment reference data by constraining sample elements to fall within a limited number of geographic domains (clusters). However, because classification error is typically positively spatially correlated, within-cluster correlation may reduce the precision of the accuracy estimates. The detailed population information to quantify a priori the effect of within-cluster correlation on precision is typically unavailable. Consequently, a convenient, practical approach to evaluate the likely performance of a two-stage cluster sample is needed. We describe such an a priori evaluation protocol focusing on the spatial distribution of the sample by land-cover class across different cluster sizes and costs of different sampling options, including options not imposing clustering. This protocol also assesses the two-stage design's adequacy for estimating the precision of accuracy estimates for rare land-cover classes. We illustrate the approach using two large-area, regional accuracy assessments from the National Land-Cover Data (NLCD), and describe how the a priorievaluation was used as a decision-making tool when implementing the NLCD design.

Use of an Inverse Method for Time Series to Estimate the Dynamics of and Management Strategies for the Box Jellyfish Carybdea marsupialis.

PubMed

Bordehore, Cesar; Fuentes, Verónica L; Segarra, Jose G; Acevedo, Melisa; Canepa, Antonio; Raventós, Josep

2015-01-01

Frequently, population ecology of marine organisms uses a descriptive approach in which their sizes and densities are plotted over time. This approach has limited usefulness for design strategies in management or modelling different scenarios. Population projection matrix models are among the most widely used tools in ecology. Unfortunately, for the majority of pelagic marine organisms, it is difficult to mark individuals and follow them over time to determine their vital rates and built a population projection matrix model. Nevertheless, it is possible to get time-series data to calculate size structure and densities of each size, in order to determine the matrix parameters. This approach is known as a "demographic inverse problem" and it is based on quadratic programming methods, but it has rarely been used on aquatic organisms. We used unpublished field data of a population of cubomedusae Carybdea marsupialis to construct a population projection matrix model and compare two different management strategies to lower population to values before year 2008 when there was no significant interaction with bathers. Those strategies were by direct removal of medusae and by reducing prey. Our results showed that removal of jellyfish from all size classes was more effective than removing only juveniles or adults. When reducing prey, the highest efficiency to lower the C. marsupialis population occurred when prey depletion affected prey of all medusae sizes. Our model fit well with the field data and may serve to design an efficient management strategy or build hypothetical scenarios such as removal of individuals or reducing prey. TThis This sdfsdshis method is applicable to other marine or terrestrial species, for which density and population structure over time are available.

Models to compare management options for a protogynous fish.

PubMed

Heppell, Selina S; Heppell, Scott A; Coleman, Felicia C; Koenig, Christopher C

2006-02-01

Populations of gag (Mycteroperca microlepis), a hermaphroditic grouper, have experienced a dramatic shift in sex ratio over the past 25 years due to a decline in older age classes. The highly female-skewed sex ratio can be predicted as a consequence of increased fishing mortality that truncates the age distribution, and raises some concern about the overall fitness of the population. Management efforts may need to be directed toward maintenance of sex ratio as well as stock size, with evaluations of recruitment based on sex ratio or male stock size in addition to the traditional female-based stock-recruitment relationship. We used two stochastic, age-structured models to heuristically compare the effects of reducing fishing mortality on different life history stages and the relative impact of reductions in fertilization rates that may occur with highly skewed sex ratios. Our response variables included population size, sex ratio, lost egg fertility, and female spawning stock biomass. Population growth rates were highest for scenarios that reduced mortality for female gag (nearshore closure), while improved sex ratios were obtained most quickly with spawning reserves. The effect of reduced fertility through sex ratio bias was generally low but depended on the management scenario employed. Our results demonstrate the utility of evaluation of fishery management scenarios through model analysis and simulation, the synergistic interaction of life history and response to changes in mortality rates, and the importance of defining management goals.

Synthesis and study of catalytic application of l-methionine protected gold nanoparticles

NASA Astrophysics Data System (ADS)

Raza, Akif; Javed, Safdar; Qureshi, Muhammad Zahid; khan, Muhammad Usman; Khan, Muhammad Saleem

2017-10-01

Gold nanoparticle is growing class of nanotechnology due to large number of uses. We synthesized stable l-methionine protected gold nanoparticles (AuNps) by in situ reduction of HAuCl4 using sodium borohydrate as reducing and l-methionine as stabilizing agent in an aqueous medium. Different parameters (pH, capping agent, precursor salt, and heating time) were optimized to see the effect on the size of particles. Double beam spectrophotometer was used to carry out the spectroscopic studies. It was observed that pH and concentration of reducing salt are deciding factors in controlling the size and morphology of AuNps. Scanning electron microscopy (SEM) verified the formation of AuNPs as predicted by UV-Vis spectra. The interaction of AuNPs with l-methionine was confirmed by Fourier Transform Infrared (FTIR). The reduction of 4-nitrophenol acted as standard of reaction to check the response of AuNps catalyst. Complete reduction of 4-nitrophenol was accomplished by AuNps sol in just 60 s. Fastest reduction rate was observed with smaller spherical particles. This study concluded that size and shape of AuNps can be monitored by controlling the pH, concentration of capping and reducing agent. It also provides an economical solution to aquatic environment in terms of time saving and use of small volume of catalytic solution for reduction of several other toxic organic pollutants.

Effects of predation and oxygen deficiency on different age classes of the amphipod Monoporeia affinis

NASA Astrophysics Data System (ADS)

Sandberg, E.; Bonsdorff, E.

1996-06-01

Predation by the big brackish-water isopod Saduria entomon on two age-classes (juveniles and adults) of the small deposit-feeding amphipod Monoporeia (syn. Pontoporeia) affinis was studied at different oxygen conditions (normoxia>11 mg/l O 2, and moderate hypoxia 4 mg/l O 2). Vulnerability of juvenile and adult M. affinis was studied in single and mixed age-class treatments. The proportions of juveniles and adults were varied at one total numerical density. The predatory effects were measured as numbers of individuals consumed and of total biomass intake (mg ash-free dry weight). The highest predation rate (in numbers) was detected in the single-prey treatment with juvenile M. affinis, both in normoxia and moderate hypoxia. No preference for any of the two size classes was found in the treatment with equal numbers of adults and juveniles. In normoxia, the total number of prey consumed decreased with increasing proportions of adults, while intake increased in terms of biomass. In moderate hypoxia, high proportions of adults reduced the predation rate of S. entomon to such an extent that also the intake in terms of biomass was significantly negatively affected.

Sella size and jaw bases - Is there a correlation???

PubMed

Neha; Mogra, Subraya; Shetty, Vorvady Surendra; Shetty, Siddarth

2016-01-01

Sella turcica is an important cephalometric structure and attempts have been made in the past to correlate its dimensions to the malocclusion. However, no study has so far compared the size of sella to the jaw bases that determine the type of malocclusion. The present study was undertaken to find out any such correlation if it exists. Lateral cephalograms of 110 adults consisting of 40 Class I, 40 Class II, and 30 Class III patients were assessed for the measurement of sella length, width, height, and area. The maxillary length, mandibular ramus height, and body length were also measured. The sella dimensions were compared among three malocclusion types by one-way ANOVA. Pearson correlation was calculated between the jaw size and sella dimensions. Furthermore, the ratio of jaw base lengths and sella area were calculated. Mean sella length, width and area were found to be greatest in Class III, followed by Class I and least in Class II though the results were not statistically significant. 3 out of 4 measured dimensions of sella, correlated significantly with mandibular ramus and body length each. However, only one dimension of sella showed significant correlation with maxilla. The mandibular ramus and body length show a nearly constant ratio to sella area (0.83-0.85, 0.64-0.65, respectively) in all the three malocclusions. Thus, mandible has a definite and better correlation to the size of sella turcica.

California's Class Size Reduction: Implications for Equity, Practice & Implementation.

ERIC Educational Resources Information Center

Wexler, Edward; Izu, JoAnn; Carlos, Lisa; Fuller, Bruce; Hayward, Gerald; Kirst, Mike

When California implemented its class-size reduction (CSR) program in 1996, a number of questions regarding financial burdens, teacher shortages, scarcity of facilities, and collective bargaining were raised. This first-year implementation study aims to provide some contextual information as background for answering questions, to clarify these…

Effects of Class Size on Alternative Educational Outcomes across Disciplines

ERIC Educational Resources Information Center

Cheng, Dorothy A.

2011-01-01

This is the first study to use self-reported ratings of student learning, instructor recommendations, and course recommendations as the outcome measure to estimate class size effects, doing so across 24 disciplines. Fixed-effects models controlling for heterogeneous courses and instructors reveal that increasing enrollment has negative and…

78 FR 42817 - Small Business Size Standards: Waiver of the Nonmanufacturer Rule

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-17

... SMALL BUSINESS ADMINISTRATION Small Business Size Standards: Waiver of the Nonmanufacturer Rule AGENCY: U.S. Small Business Administration. ACTION: Notice of intent to rescind the class waiver of the... Manufacturing. SUMMARY: The U. S. Small Business Administration (SBA) intends to rescind a class waiver of the...

Financing Class Size Reduction

ERIC Educational Resources Information Center

Achilles, C. M.

2005-01-01

Class size reduction has been shown to, among other things, improve academic achievement for all students and particularly for low-income and minority students. With the No Child Left Behind Act's heavy emphasis on scientifically based research, adequate yearly progress, and disaggregated results, one wonders why all children aren't enrolled in…

Sizing Up What Matters.

ERIC Educational Resources Information Center

McCluskey, Neal

"Smaller is better" is often the mantra of school leaders with regard to class size, while the benefits of smaller schools are ignored. Benefits of small classes seem obvious--teachers with fewer students could devote more time to each student. Conducted in 1985-89, Tennessee's Project STAR (Student/Teacher Achievement Ratio) found that…

Influences of Teaching Approaches and Class Size on Undergraduate Mathematical Learning

ERIC Educational Resources Information Center

Olson, Jo Clay; Cooper, Sandy; Lougheed, Tom

2011-01-01

An issue for many mathematics departments is the success rate of precalculus students. In an effort to increase the success rate, this quantitative study investigated how class size and teaching approach influenced student achievement and students' attitudes towards learning mathematics. Students' achievement and their attitudes toward learning…

Educational Production and Teacher Preferences

ERIC Educational Resources Information Center

Bosworth, Ryan; Caliendo, Frank

2007-01-01

We develop a simple model of teacher behavior that offers a solution to the ''class size puzzle'' and is useful for analyzing the potential effects of the No Child Left Behind Act. When teachers must allocate limited classroom time between multiple instructional methods, rational teachers may respond to reductions in class size by reallocating…

Thin-plate spline analysis of the cranial base in subjects with Class III malocclusion.

PubMed

Singh, G D; McNamara, J A; Lozanoff, S

1997-08-01

The role of the cranial base in the emergence of Class III malocclusion is not fully understood. This study determines deformations that contribute to a Class III cranial base morphology, employing thin-plate spline analysis on lateral cephalographs. A total of 73 children of European-American descent aged between 5 and 11 years of age with Class III malocclusion were compared with an equivalent group of subjects with a normal, untreated, Class I molar occlusion. The cephalographs were traced, checked and subdivided into seven age- and sex-matched groups. Thirteen points on the cranial base were identified and digitized. The datasets were scaled to an equivalent size, and statistical analysis indicated significant differences between average Class I and Class III cranial base morphologies for each group. Thin-plate spline analysis indicated that both affine (uniform) and non-affine transformations contribute toward the total spline for each average cranial base morphology at each age group analysed. For non-affine transformations, Partial warps 10, 8 and 7 had high magnitudes, indicating large-scale deformations affecting Bolton point, basion, pterygo-maxillare, Ricketts' point and articulare. In contrast, high eigenvalues associated with Partial warps 1-3, indicating localized shape changes, were found at tuberculum sellae, sella, and the frontonasomaxillary suture. It is concluded that large spatial-scale deformations affect the occipital complex of the cranial base and sphenoidal region, in combination with localized distortions at the frontonasal suture. These deformations may contribute to reduced orthocephalization or deficient flattening of the cranial base antero-posteriorly that, in turn, leads to the formation of a Class III malocclusion.

Preferential attachment and growth dynamics in complex systems

NASA Astrophysics Data System (ADS)

Yamasaki, Kazuko; Matia, Kaushik; Buldyrev, Sergey V.; Fu, Dongfeng; Pammolli, Fabio; Riccaboni, Massimo; Stanley, H. Eugene

2006-09-01

Complex systems can be characterized by classes of equivalency of their elements defined according to system specific rules. We propose a generalized preferential attachment model to describe the class size distribution. The model postulates preferential growth of the existing classes and the steady influx of new classes. According to the model, the distribution changes from a pure exponential form for zero influx of new classes to a power law with an exponential cut-off form when the influx of new classes is substantial. Predictions of the model are tested through the analysis of a unique industrial database, which covers both elementary units (products) and classes (markets, firms) in a given industry (pharmaceuticals), covering the entire size distribution. The model’s predictions are in good agreement with the data. The paper sheds light on the emergence of the exponent τ≈2 observed as a universal feature of many biological, social and economic problems.

Class Enumeration and Parameter Recovery of Growth Mixture Modeling and Second-Order Growth Mixture Modeling in the Presence of Measurement Noninvariance between Latent Classes

PubMed Central

Kim, Eun Sook; Wang, Yan

2017-01-01

Population heterogeneity in growth trajectories can be detected with growth mixture modeling (GMM). It is common that researchers compute composite scores of repeated measures and use them as multiple indicators of growth factors (baseline performance and growth) assuming measurement invariance between latent classes. Considering that the assumption of measurement invariance does not always hold, we investigate the impact of measurement noninvariance on class enumeration and parameter recovery in GMM through a Monte Carlo simulation study (Study 1). In Study 2, we examine the class enumeration and parameter recovery of the second-order growth mixture modeling (SOGMM) that incorporates measurement models at the first order level. Thus, SOGMM estimates growth trajectory parameters with reliable sources of variance, that is, common factor variance of repeated measures and allows heterogeneity in measurement parameters between latent classes. The class enumeration rates are examined with information criteria such as AIC, BIC, sample-size adjusted BIC, and hierarchical BIC under various simulation conditions. The results of Study 1 showed that the parameter estimates of baseline performance and growth factor means were biased to the degree of measurement noninvariance even when the correct number of latent classes was extracted. In Study 2, the class enumeration accuracy of SOGMM depended on information criteria, class separation, and sample size. The estimates of baseline performance and growth factor mean differences between classes were generally unbiased but the size of measurement noninvariance was underestimated. Overall, SOGMM is advantageous in that it yields unbiased estimates of growth trajectory parameters and more accurate class enumeration compared to GMM by incorporating measurement models. PMID:28928691

Prey size selection and cannibalistic behaviour of juvenile barramundi Lates calcarifer.

PubMed

Ribeiro, F F; Qin, J G

2015-05-01

This study assessed the cannibalistic behaviour of juvenile barramundi Lates calcarifer and examined the relationship between prey size selection and energy gain of cannibals. Prey handling time and capture success by cannibals were used to estimate the ratio of energy gain to energy cost in prey selection. Cannibals selected smaller prey despite its capability of ingesting larger prey individuals. In behavioural analysis, prey handling time significantly increased with prey size, but it was not significantly affected by cannibal size. Conversely, capture success significantly decreased with the increase of both prey and cannibal sizes. The profitability indices showed that the smaller prey provides the most energy return for cannibals of all size classes. These results indicate that L. calcarifer cannibals select smaller prey for more profitable return. The behavioural analysis, however, indicates that L. calcarifer cannibals attack prey of all size at a similar rate but ingest smaller prey more often, suggesting that prey size selection is passively orientated rather than at the predator's choice. The increase of prey escape ability and morphological constraint contribute to the reduction of intracohort cannibalism as fish grow larger. This study contributes to the understanding of intracohort cannibalism and development of strategies to reduce fish cannibalistic mortalities. © 2015 The Fisheries Society of the British Isles.

The design and evolution of the beta two-stage-to-orbit horizontal takeoff and landing launch system

NASA Technical Reports Server (NTRS)

Burkardt, Leo A.; Norris, Rick B.

1992-01-01

The Beta launch system was originally conceived in 1986 as a horizontal takeoff and landing, fully reusable, two-stage-to-orbit, manned launch vehicle to replace the Shuttle. It was to be capable of delivering a 50,000 lb. payload to low polar orbit. The booster propulsion system consisted of JP fueled turbojets and LH fueled ramjets mounted in pods in an over/under arrangement, and a single LOX/LH fueled SSME rocket. The second stage orbiter, which staged at Mach 8, was powered by an SSME rocket. A major goal was to develop a vehicle design consistent with near term technology. The vehicle design was completed with a GLOW of approximately 2,000,000 lbs. All design goals were met. Since then, interest has shifted to the 10,000 lbs. to low polar orbit payload class. The original Beta was down-sized to meet this payload class. The GLOW of the down-sized vehicle was approximately 1,000,000 lbs. The booster was converted to exclusively air-breathing operation. Because the booster depends on conventional air-breathing propulsion only, the staging Mach number was reduced to 5.5. The orbiter remains an SSME rocket-powered stage.

NAS Parallel Benchmarks. 2.4

NASA Technical Reports Server (NTRS)

VanderWijngaart, Rob; Biegel, Bryan A. (Technical Monitor)

2002-01-01

We describe a new problem size, called Class D, for the NAS Parallel Benchmarks (NPB), whose MPI source code implementation is being released as NPB 2.4. A brief rationale is given for how the new class is derived. We also describe the modifications made to the MPI (Message Passing Interface) implementation to allow the new class to be run on systems with 32-bit integers, and with moderate amounts of memory. Finally, we give the verification values for the new problem size.

Testing functional and morphological interpretations of enamel thickness along the deciduous tooth row in human children.

PubMed

Mahoney, Patrick

2013-08-01

The significance of a gradient in enamel thickness along the human permanent molar row has been debated in the literature. Some attribute increased enamel thickness from first to third molars to greater bite force during chewing. Others argue that thicker third molar enamel relates to a smaller crown size facilitated by a reduced dentin component. Thus, differences in morphology, not function, explains enamel thickness. This study draws on these different interpretive models to assess enamel thickness along the entire human deciduous tooth row. Average enamel thickness (AET), the area and proportion of crown enamel and dentin, and a crown size proxy are calculated for incisors, canines, and molars. Allometric scaling relationships are assessed within each tooth class, and then comparisons are undertaken along the row. Generally, AET was correlated with crown size and scaled with isometry, except for second molars which scaled with positive allometry. Mean AET increased along the row and was greater on molars, where bite forces are reported to be higher. Second molars combined the largest crown size with the thickest enamel and the smallest proportion of dentin, which is consistent with a reduction in the potential for cusp fracture under high bite forces. Resistance to wear may also account for some enamel thickness variation between tooth classes. Dental reduction did not explain the trend in AET from central to lateral incisors, or from first to second molars. The gradient in AET along the deciduous tooth row is partly consistent with a functional interpretation of enamel thickness. Copyright © 2013 Wiley Periodicals, Inc.

Transitions in Smokers’ Social Networks After Quit Attempts: A Latent Transition Analysis

PubMed Central

Smith, Rachel A.; Piper, Megan E.; Roberts, Linda J.; Baker, Timothy B.

2016-01-01

Introduction: Smokers’ social networks vary in size, composition, and amount of exposure to smoking. The extent to which smokers’ social networks change after a quit attempt is unknown, as is the relation between quitting success and later network changes. Methods: Unique types of social networks for 691 smokers enrolled in a smoking-cessation trial were identified based on network size, new network members, members’ smoking habits, within network smoking, smoking buddies, and romantic partners’ smoking. Latent transition analysis was used to identify the network classes and to predict transitions in class membership across 3 years from biochemically assessed smoking abstinence. Results: Five network classes were identified: Immersed (large network, extensive smoking exposure including smoking buddies), Low Smoking Exposure (large network, minimal smoking exposure), Smoking Partner (small network, smoking exposure primarily from partner), Isolated (small network, minimal smoking exposure), and Distant Smoking Exposure (small network, considerable nonpartner smoking exposure). Abstinence at years 1 and 2 was associated with shifts in participants’ social networks to less contact with smokers and larger networks in years 2 and 3. Conclusions: In the years following a smoking-cessation attempt, smokers’ social networks changed, and abstinence status predicted these changes. Networks defined by high levels of exposure to smokers were especially associated with continued smoking. Abstinence, however, predicted transitions to larger social networks comprising less smoking exposure. These results support treatments that aim to reduce exposure to smoking cues and smokers, including partners who smoke. Implications: Prior research has shown that social network features predict the likelihood of subsequent smoking cessation. The current research illustrates how successful quitting predicts social network change over 3 years following a quit attempt. Specifically, abstinence predicts transitions to networks that are larger and afford less exposure to smokers. This suggests that quitting smoking may expand a person’s social milieu rather than narrow it. This effect, plus reduced exposure to smokers, may help sustain abstinence. PMID:27613925

Class Size Reduction or Rapid Formative Assessment?: A Comparison of Cost-Effectiveness

ERIC Educational Resources Information Center

Yeh, Stuart S.

2009-01-01

The cost-effectiveness of class size reduction (CSR) was compared with the cost-effectiveness of rapid formative assessment, a promising alternative for raising student achievement. Drawing upon existing meta-analyses of the effects of student-teacher ratio, evaluations of CSR in Tennessee, California, and Wisconsin, and RAND cost estimates, CSR…

Class Size Reduction in a Large Urban School District: A Mixed Methodology Evaluation Research Study.

ERIC Educational Resources Information Center

Munoz, Marco A.

This study evaluated the Class Size Reduction (CSR) program in 34 elementary schools in Kentucky's Jefferson County Public Schools. The CSR program is a federal initiative to help elementary schools improve student learning by hiring additional teachers. Qualitative data were collected using unstructured interviews, site observations, and document…

Class Size Reduction: Great Hopes, Great Challenges. Policy Brief.

ERIC Educational Resources Information Center

WestEd, San Francisco, CA.

This policy brief examines the benefits and the challenges that accompany class-size reduction (CSR). It suggests that when designing CSR programs, states should carefully assess specific circumstances in their schools as they adopt or modify CSR efforts to avoid the unintended consequences that some programs have experienced. Some of the…

The Effects of Class Size on Students' Academic Achievement

ERIC Educational Resources Information Center

Wilson, Claire

2011-01-01

The purpose of this quantitative correlational research was to study the relationship between class size and students' academic achievement. Citywide language arts and math test scores for third and fifth grade students in four New York City public schools were examined using a variety of variables including (a) gender, (b) ethnicity, (c) grade…

Relationship of Class-Size to Classroom Processes, Teacher Satisfaction and Pupil Affect: A Meta-Analysis.

ERIC Educational Resources Information Center

Smith, Mary Lee; Glass, Gene V.

Using data from previously completed research, the authors of this report attempted to examine the relationship between class size and measures of outcomes such as student attitudes and behavior, classroom processes and learning environment, and teacher satisfaction. The authors report that statistical integration of the existing research…

Smart Class-Size Policies for Lean Times. SREB Policy Brief

ERIC Educational Resources Information Center

Gagne, Jeff

2012-01-01

Most states nationwide have had policies for several decades that limit the number of students assigned to public K-12 classrooms. Southern Regional Education Board (SREB) states, led by Tennessee and Texas, spearheaded this effort in the 1980s, and SREB's own "Legislative Briefings" have marked the growth of class-size policies across…

Forest fragmentation of southern U.S. bottomland hardwoods

Treesearch

Victor A. Rudis

1993-01-01

The magnitude and character of forest fragmentation are evaluated for bottomland hardwoods in the southern United States.Fragment size class is significantly associated with the frequency of bottomland hardwood species, stand size and ownership classes, and land use attributes.Differences in the frequency of indicators of multiple values are apparent. Two diverse...

40 CFR 113.4 - Size classes and associated liability limits for fixed onshore oil storage facilities, 1,000...

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 21 2010-07-01 2010-07-01 false Size classes and associated liability... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS LIABILITY LIMITS FOR... privity and knowledge of the owner or operator, the following limits of liability are established for...

Impact of removable partial denture prosthesis on chewing efficiency

PubMed Central

BESSADET, Marion; NICOLAS, Emmanuel; SOCHAT, Marine; HENNEQUIN, Martine; VEYRUNE, Jean-Luc

2013-01-01

Removable partial denture prostheses are still being used for anatomic, medical and economic reasons. However, the impact on chewing parameters is poorly described. Objectives The objective of this study was to estimate the impact of removable partial denture prosthesis on masticatory parameters. Material and Methods Nineteen removable partial denture prosthesis (RPDP) wearers participated in the study. Among them, 10 subjects were Kennedy Class III partially edentulous and 9 with posterior edentulism (Class I). All presented a complete and full dentate opposing arch. The subjects chewed samples of carrots and peanuts with and without their prosthesis. The granulometry of the expectorated boluses from carrot and peanuts was characterized by median particle size (D50), determined at the natural point of swallowing. Number of chewing cycles (CC), chewing time (CT) and chewing frequency (CF=CC/CT) were video recorded. Results With RPDP, the mean D50 values for carrot and peanuts were lower [Repeated Model Procedures (RMP), F=15, p<0.001] regardless of the type of Kennedy Class. For each food, mean CC, CT and CF values recorded decreased (RMP, F=18, F=9, and F=20 respectively, p<0.01). With or without RPD, the boluses' granulometry values were above the masticatory normative index (MNI) determined as 4,000 µm. Conclusion RPDP rehabilitation improves the ability to reduce the bolus particle size, but does not reestablish fully the masticatory function. Clinical relevance This study encourages the clinical improvement of oral rehabilitation procedure. PMID:24212983

Two Universality Classes for the Many-Body Localization Transition

NASA Astrophysics Data System (ADS)

Khemani, Vedika; Sheng, D. N.; Huse, David A.

2017-08-01

We provide a systematic comparison of the many-body localization (MBL) transition in spin chains with nonrandom quasiperiodic versus random fields. We find evidence suggesting that these belong to two separate universality classes: the first dominated by "intrinsic" intrasample randomness, and the second dominated by external intersample quenched randomness. We show that the effects of intersample quenched randomness are strongly growing, but not yet dominant, at the system sizes probed by exact-diagonalization studies on random models. Thus, the observed finite-size critical scaling collapses in such studies appear to be in a preasymptotic regime near the nonrandom universality class, but showing signs of the initial crossover towards the external-randomness-dominated universality class. Our results provide an explanation for why exact-diagonalization studies on random models see an apparent scaling near the transition while also obtaining finite-size scaling exponents that strongly violate Harris-Chayes bounds that apply to disorder-driven transitions. We also show that the MBL phase is more stable for the quasiperiodic model as compared to the random one, and the transition in the quasiperiodic model suffers less from certain finite-size effects.

Annual variation in neustonic micro- and meso-plastic particles and zooplankton in the Bay of Calvi (Mediterranean-Corsica).

PubMed

Collignon, Amandine; Hecq, Jean-Henri; Galgani, François; Collard, France; Goffart, Anne

2014-02-15

The annual variation in neustonic plastic particles and zooplankton was studied in the Bay of Calvi (Corsica) between 30 August 2011 and 7 August 2012. Plastic particles were classified into three size classes, small microplastics (0.2-2mm), large microplastics (2-5mm) and mesoplastics (5-10mm). 74% of the 38 samples contained plastic particles of varying composition: e.g. filaments, polystyrene, thin plastic films. An average concentration of 6.2 particles/100 m(2) was observed. The highest abundance values (69 particles/100 m(2)) observed occurred during periods of low offshore wind conditions. These values rose in the same order of magnitude as in previous studies in the North Western Mediterranean. The relationships between the abundance values of the size classes between zooplankton and plastic particles were then examined. The ratio for the intermediate size class (2-5mm) reached 2.73. This would suggest a potential confusion for predators regarding planktonic prey of this size class. Copyright © 2013 Elsevier Ltd. All rights reserved.

Mixture models for estimating the size of a closed population when capture rates vary among individuals

USGS Publications Warehouse

Dorazio, R.M.; Royle, J. Andrew

2003-01-01

We develop a parameterization of the beta-binomial mixture that provides sensible inferences about the size of a closed population when probabilities of capture or detection vary among individuals. Three classes of mixture models (beta-binomial, logistic-normal, and latent-class) are fitted to recaptures of snowshoe hares for estimating abundance and to counts of bird species for estimating species richness. In both sets of data, rates of detection appear to vary more among individuals (animals or species) than among sampling occasions or locations. The estimates of population size and species richness are sensitive to model-specific assumptions about the latent distribution of individual rates of detection. We demonstrate using simulation experiments that conventional diagnostics for assessing model adequacy, such as deviance, cannot be relied on for selecting classes of mixture models that produce valid inferences about population size. Prior knowledge about sources of individual heterogeneity in detection rates, if available, should be used to help select among classes of mixture models that are to be used for inference.

Three tiers of genome evolution in reptiles

PubMed Central

Organ, Chris L.; Moreno, Ricardo Godínez; Edwards, Scott V.

2008-01-01

Characterization of reptilian genomes is essential for understanding the overall diversity and evolution of amniote genomes, because reptiles, which include birds, constitute a major fraction of the amniote evolutionary tree. To better understand the evolution and diversity of genomic characteristics in Reptilia, we conducted comparative analyses of online sequence data from Alligator mississippiensis (alligator) and Sphenodon punctatus (tuatara) as well as genome size and karyological data from a wide range of reptilian species. At the whole-genome and chromosomal tiers of organization, we find that reptilian genome size distribution is consistent with a model of continuous gradual evolution while genomic compartmentalization, as manifested in the number of microchromosomes and macrochromosomes, appears to have undergone early rapid change. At the sequence level, the third genomic tier, we find that exon size in Alligator is distributed in a pattern matching that of exons in Gallus (chicken), especially in the 101—200 bp size class. A small spike in the fraction of exons in the 301 bp—1 kb size class is also observed for Alligator, but more so for Sphenodon. For introns, we find that members of Reptilia have a larger fraction of introns within the 101 bp–2 kb size class and a lower fraction of introns within the 5–30 kb size class than do mammals. These findings suggest that the mode of reptilian genome evolution varies across three hierarchical levels of the genome, a pattern consistent with a mosaic model of genomic evolution. PMID:21669810

Chemical Characterization and Source Apportionment of Size Fractionated Atmospheric Aerosols, and, Evaluating Student Attitudes and Learning in Large Lecture General Chemistry Classes

NASA Astrophysics Data System (ADS)

Allen, Gregory Harold

Chemical speciation and source apportionment of size fractionated atmospheric aerosols were investigated using laser desorption time-of-flight mass spectrometry (LD TOF-MS) and source apportionment was carried out using carbon-14 accelerator mass spectrometry (14C AMS). Sample collection was carried out using the Davis Rotating-drum Unit for Monitoring impact analyzer in Davis, Colfax, and Yosemite, CA. Ambient atmospheric aerosols collected during the winter of 2010/11 and 2011/12 showed a significant difference in the types of compounds found in the small and large sized particles. The difference was due to the increase number of oxidized carbon species that were found in the small particles size ranges, but not in the large particles size ranges. Overall, the ambient atmospheric aerosols collected during the winter in Davis, CA had and average fraction modern of F14C = 0.753 +/- 0.006, indicating that the majority of the size fractionated particles originated from biogenic sources. Samples collected during the King Fire in Colfax, CA were used to determine the contribution of biomass burning (wildfire) aerosols. Factor analysis was used to reduce the ions found in the LD TOF-MS analysis of the King Fire samples. The final factor analysis generated a total of four factors that explained an overall 83% of the variance in the data set. Two of the factors correlated heavily with increased smoke events during the sample period. The increased smoke events produced a large number of highly oxidized organic aerosols (OOA2) and aromatic compounds that are indicative of biomass burning organic aerosols (WBOA). The signal intensities of the factors generated in the King Fire data were investigated in samples collected in Yosemite and Davis, CA to look at the impact of biomass burning on ambient atmospheric aerosols. In both comparison sample collections the OOA2 and WBOA factors both increased during biomass burning events located near the sampling sites. The correlation between the OOA2 and WBOA factors and smoke levels indicates that these factors can be used to identify the influence of biomass burning on ambient aerosols. The effectiveness of using the ChemWiki instead of a traditional textbook was investigated during the spring quarter of 2014. Student performance was measured using common midterms, a final, and a pre/post content exams. We also employed surveys, the Colorado Learning Attitudes about Science Survey (CLASS) for Chemistry, and a weekly time-on-task survey to quantify students' attitudes and study habits. The effectiveness of the ChemWiki compared to a traditional textbook was examined using multiple linear regression analysis with a standard non-inferiority testing framework. Results show that the performance of students in the section who were assigned readings from the ChemWiki was non-inferior to the performance of students in the section who were assigned readings from the traditional textbook, indicating that the ChemWiki does not substantially differ from the standard textbook in terms of student learning outcomes. The results from the surveys also suggest that the two classes were similar in their beliefs about chemistry and overall average time spent studying. These results indicate that the ChemWiki is a viable cost-saving alternative to traditional textbooks. The impact of using active learning techniques in a large lecture general chemistry class was investigated by assessing student performance and attitudes during the fall 2014 and winter 2015 quarters. One instructor applied active learning strategies while the remaining instructors employed more traditional lecture styles. Student performance, learning, learning environments, and attitudes were measured using a standardized pre/post exams, common final exams, classroom observations, and the CLASS chemistry instrument in large lecture general chemistry courses. Classroom observation data showed that the active learning class was the most student centered and of the other classes two instructors were transitional in their teaching style and the remaining two primarily employed traditional lecture techniques. The active learning class had the highest student performance but the difference was only statistically significant when compared to the two traditional lecture classes. Overall, our data showed a trend that student performance increased as the instructional style became more student centered. Student attitudes didn't seem to correlate with any specific instructional style and the students in the active learning class had similar attitudes to the other general students. The active learning class was successful in increasing the average time students spent studying outside of the class, a statistically significant difference of about 1.5 to 3.0 hrs/week.

49 CFR 172.446 - CLASS 9 label.

Code of Federal Regulations, 2010 CFR

2010-10-01

... the six white spaces between them. The lower half of the label must be white with the class number “9... 49 Transportation 2 2010-10-01 2010-10-01 false CLASS 9 label. 172.446 Section 172.446... SECURITY PLANS Labeling § 172.446 CLASS 9 label. (a) Except for size and color, the “CLASS 9...

Small is Beautiful When...

ERIC Educational Resources Information Center

Dixon, Annabelle

1980-01-01

The author, Deputy Head of Chalk Dell Infant School in Hertford, England, reviews research on the effects of class size and analyzes her own experience with a class of 33 and a class of 23 students. (Editor/SJL)

Arabidopsis Class I and Class II TCP Transcription Factors Regulate Jasmonic Acid Metabolism and Leaf Development Antagonistically1[C][W

PubMed Central

Danisman, Selahattin; van der Wal, Froukje; Dhondt, Stijn; Waites, Richard; de Folter, Stefan; Bimbo, Andrea; van Dijk, Aalt DJ; Muino, Jose M.; Cutri, Lucas; Dornelas, Marcelo C.; Angenent, Gerco C.; Immink, Richard G.H.

2012-01-01

TEOSINTE BRANCHED1/CYCLOIDEA/PROLIFERATING CELL FACTOR1 (TCP) transcription factors control developmental processes in plants. The 24 TCP transcription factors encoded in the Arabidopsis (Arabidopsis thaliana) genome are divided into two classes, class I and class II TCPs, which are proposed to act antagonistically. We performed a detailed phenotypic analysis of the class I tcp20 mutant, showing an increase in leaf pavement cell sizes in 10-d-old seedlings. Subsequently, a glucocorticoid receptor induction assay was performed, aiming to identify potential target genes of the TCP20 protein during leaf development. The LIPOXYGENASE2 (LOX2) and class I TCP9 genes were identified as TCP20 targets, and binding of TCP20 to their regulatory sequences could be confirmed by chromatin immunoprecipitation analyses. LOX2 encodes for a jasmonate biosynthesis gene, which is also targeted by class II TCP proteins that are under the control of the microRNA JAGGED AND WAVY (JAW), although in an antagonistic manner. Mutation of TCP9, the second identified TCP20 target, resulted in increased pavement cell sizes during early leaf developmental stages. Analysis of senescence in the single tcp9 and tcp20 mutants and the tcp9tcp20 double mutants showed an earlier onset of this process in comparison with wild-type control plants in the double mutant only. Both the cell size and senescence phenotypes are opposite to the known class II TCP mutant phenotype in JAW plants. Altogether, these results point to an antagonistic function of class I and class II TCP proteins in the control of leaf development via the jasmonate signaling pathway. PMID:22718775

A Note on Cluster Effects in Latent Class Analysis

ERIC Educational Resources Information Center

Kaplan, David; Keller, Bryan

2011-01-01

This article examines the effects of clustering in latent class analysis. A comprehensive simulation study is conducted, which begins by specifying a true multilevel latent class model with varying within- and between-cluster sample sizes, varying latent class proportions, and varying intraclass correlations. These models are then estimated under…

Speech Music Discrimination Using Class-Specific Features

DTIC Science & Technology

2004-08-01

Speech Music Discrimination Using Class-Specific Features Thomas Beierholm...between speech and music . Feature extraction is class-specific and can therefore be tailored to each class meaning that segment size, model orders...interest. Some of the applications of audio signal classification are speech/ music classification [1], acoustical environmental classification [2][3

Statistical Analyses of Femur Parameters for Designing Anatomical Plates.

PubMed

Wang, Lin; He, Kunjin; Chen, Zhengming

2016-01-01

Femur parameters are key prerequisites for scientifically designing anatomical plates. Meanwhile, individual differences in femurs present a challenge to design well-fitting anatomical plates. Therefore, to design anatomical plates more scientifically, analyses of femur parameters with statistical methods were performed in this study. The specific steps were as follows. First, taking eight anatomical femur parameters as variables, 100 femur samples were classified into three classes with factor analysis and Q-type cluster analysis. Second, based on the mean parameter values of the three classes of femurs, three sizes of average anatomical plates corresponding to the three classes of femurs were designed. Finally, based on Bayes discriminant analysis, a new femur could be assigned to the proper class. Thereafter, the average anatomical plate suitable for that new femur was selected from the three available sizes of plates. Experimental results showed that the classification of femurs was quite reasonable based on the anatomical aspects of the femurs. For instance, three sizes of condylar buttress plates were designed. Meanwhile, 20 new femurs are judged to which classes the femurs belong. Thereafter, suitable condylar buttress plates were determined and selected.

Energy Current Cumulants in One-Dimensional Systems in Equilibrium

NASA Astrophysics Data System (ADS)

Dhar, Abhishek; Saito, Keiji; Roy, Anjan

2018-06-01

A recent theory based on fluctuating hydrodynamics predicts that one-dimensional interacting systems with particle, momentum, and energy conservation exhibit anomalous transport that falls into two main universality classes. The classification is based on behavior of equilibrium dynamical correlations of the conserved quantities. One class is characterized by sound modes with Kardar-Parisi-Zhang scaling, while the second class has diffusive sound modes. The heat mode follows Lévy statistics, with different exponents for the two classes. Here we consider heat current fluctuations in two specific systems, which are expected to be in the above two universality classes, namely, a hard particle gas with Hamiltonian dynamics and a harmonic chain with momentum conserving stochastic dynamics. Numerical simulations show completely different system-size dependence of current cumulants in these two systems. We explain this numerical observation using a phenomenological model of Lévy walkers with inputs from fluctuating hydrodynamics. This consistently explains the system-size dependence of heat current fluctuations. For the latter system, we derive the cumulant-generating function from a more microscopic theory, which also gives the same system-size dependence of cumulants.

Alcohol policies and practices among four-year colleges in the United States: prevalence and patterns.

PubMed

Lenk, Kathleen M; Erickson, Darin J; Nelson, Toben F; Winters, Ken C; Toomey, Traci L

2012-05-01

The purpose of this study was to assess the prevalence of college alcohol policies and practices and to identify patterns of policies/practices across colleges. An online survey of administrators at a random sample of 351 4-year U.S. colleges was conducted in 2008. The prevalence of 31 alcohol policies and practices was assessed as well as differences across size and type of colleges. Latent class analyses identified classes of colleges based on their alcohol policies/practices. The majority of colleges prohibit alcohol use at sporting events, whereas less than half prohibit alcohol use at fraternity and sorority events. Less than half of the colleges also prohibit alcohol advertising in/on campus newspapers and radio stations. Small colleges are more likely than large colleges to prohibit alcohol use at tailgating events and to prohibit newspaper alcohol advertising. Public colleges are more likely than private colleges to prohibit alcohol use in dorms but less likely to prohibit alcohol advertising. We identified four classes of colleges-the largest class (38%) was characterized by having many alcohol policies/practices, the smallest class (13%) had none or few alcohol policies/practices, and the remainder fit into two middle classes that had certain policies/practices in place but lacked others. Most colleges report implementing some alcohol policies/ practices but are lacking others. Only two of every five colleges fit into a class that has many alcohol policies. More studies are needed to validate our findings and assess whether certain policies/practices and patterns of policies are associated with reducing student alcohol consumption and related problems.

Four Reasons to Question the Accuracy of a Biotic Index; the Risk of Metric Bias and the Scope to Improve Accuracy

PubMed Central

Monaghan, Kieran A.

2016-01-01

Natural ecological variability and analytical design can bias the derived value of a biotic index through the variable influence of indicator body-size, abundance, richness, and ascribed tolerance scores. Descriptive statistics highlight this risk for 26 aquatic indicator systems; detailed analysis is provided for contrasting weighted-average indices applying the example of the BMWP, which has the best supporting data. Differences in body size between taxa from respective tolerance classes is a common feature of indicator systems; in some it represents a trend ranging from comparatively small pollution tolerant to larger intolerant organisms. Under this scenario, the propensity to collect a greater proportion of smaller organisms is associated with negative bias however, positive bias may occur when equipment (e.g. mesh-size) selectively samples larger organisms. Biotic indices are often derived from systems where indicator taxa are unevenly distributed along the gradient of tolerance classes. Such skews in indicator richness can distort index values in the direction of taxonomically rich indicator classes with the subsequent degree of bias related to the treatment of abundance data. The misclassification of indicator taxa causes bias that varies with the magnitude of the misclassification, the relative abundance of misclassified taxa and the treatment of abundance data. These artifacts of assessment design can compromise the ability to monitor biological quality. The statistical treatment of abundance data and the manipulation of indicator assignment and class richness can be used to improve index accuracy. While advances in methods of data collection (i.e. DNA barcoding) may facilitate improvement, the scope to reduce systematic bias is ultimately limited to a strategy of optimal compromise. The shortfall in accuracy must be addressed by statistical pragmatism. At any particular site, the net bias is a probabilistic function of the sample data, resulting in an error variance around an average deviation. Following standardized protocols and assigning precise reference conditions, the error variance of their comparative ratio (test-site:reference) can be measured and used to estimate the accuracy of the resultant assessment. PMID:27392036

Accuracy assessment of percent canopy cover, cover type, and size class

Treesearch

H. T. Schreuder; S. Bain; R. C. Czaplewski

2003-01-01

Truth for vegetation cover percent and type is obtained from very large-scale photography (VLSP), stand structure as measured by size classes, and vegetation types from a combination of VLSP and ground sampling. We recommend using the Kappa statistic with bootstrap confidence intervals for overall accuracy, and similarly bootstrap confidence intervals for percent...

Principals as Middle Managers: School Leadership during the Implementation of Primary Class Size Reduction Policy in Ontario

ERIC Educational Resources Information Center

Flessa, Joseph J.

2012-01-01

Previous work on policy implementation has often suggested that schools leave their "thumbprints" on policies received from above. During the implementation of Primary Class Size Reduction (PCS) Initiative in Ontario, Canada, however, school principals spoke with remarkable uniformity about the ways PCS affected their work. This article…

District Resource Capacity and the Effects of Educational Policy: The Case of Primary Class Size Reduction in Ontario

ERIC Educational Resources Information Center

Mascall, Blair; Leung, Joannie

2012-01-01

In a study of Ontario, Canada's province-wide Primary Class Size Reduction (PCS) Initiative, school districts' ability to direct and support schools was related to their experience with planning and monitoring, interest in innovation, and its human and fiscal resource base. Districts with greater "resource capacity" were able to…

Relationship between Class Size and Students' Opportunity to Learn Writing in Middle School

ERIC Educational Resources Information Center

Tienken, Christopher H.; Achilles, Charles M.

2009-01-01

Class-size reduction (CSR) initiatives have demonstrated positive short- and long-term effects in elementary grades. Less is known about CSR influence on achievement in middle grades. Thus, we conducted a non-experimental, longitudinal, explanatory study of CSR influence on writing achievement of 3 independent cohorts of students (n = 123) in…

An Evaluation of the Federal Class-Size Reduction Program in Wake County, North Carolina--1999-2000.

ERIC Educational Resources Information Center

Scudder, David F.

An empirical evaluation of the federal class-size reduction (CSR) program in Wake County, North Carolina, during the 1999-2000 school year is presented. The qualitative process evaluation showed implementation issues involving the mechanics and the meaning of CSR. Often, schools did not understand where CSR occurred because of changing enrollment…

Learning Approaches and Lecture Attendance of Medical Students

ERIC Educational Resources Information Center

Bates, Madeleine; Curtis, Sally; Dismore, Harriet

2018-01-01

There are arguably many factors that affect the way a student learns. A recent report by the Higher Education Policy Institute (HEPI) and the Higher Education Academy (HEA) on student academic experience in the UK states that class size is an important factor in the quality of the student experience and that smaller class sizes provide greater…

A Plan for the Evaluation of California's Class Size Reduction Initiative.

ERIC Educational Resources Information Center

Kirst, Michael; Bomstedt, George; Stecher, Brian

In July 1996, California began its Class Size Reduction (CSR) Initiative. To gauge the effectiveness of this initiative, an analysis of its objectives and an overview of proposed strategies for evaluating CSR are presented here. An outline of the major challenges that stand between CSR and its mission are provided. These include logistical…

Ontario's Primary Class Size Reduction Initiative: Report on Early Implementation

ERIC Educational Resources Information Center

Bascia, Nina

2010-01-01

Reduction in the size of classes from Kindergarten to Grade 3 was a major Liberal Party campaign promise in Ontario's 2003 provincial election. It was intended to demonstrate a new government's commitment to improving public education. By the 2008-09 school year, the provincial government's goals had been achieved: over 90% of all primary classes…

You Just Feed Them with a Long-Handled Spoon: Families Evaluate Their Experiences in a Class Size Reduction Reform

ERIC Educational Resources Information Center

Graue, M. Elizabeth; Oen, Denise

2009-01-01

Emerging from an evaluation of Wisconsin's Student Achievement Guarantee in Education program (SAGE), a multidimensional program popularly known for its class size reduction component, this article examines SAGE's "lighted schoolhouse" initiative aimed to strengthen links between home and school. Drawing on family focus groups held at…

Study of Cost of Distance Education Institutes with Different Size Classes in India.

ERIC Educational Resources Information Center

Datt, Ruddar

A study of the cost of distance education institutes in India with different size classes involved nine institutions. The sample included 47 percent of total enrollment in distance education institutions in India. The study was restricted to recurring costs and examined the shares of different components of costs and the sources of funding. It…

Using Flexible Busing to Meet Average Class Size Targets

ERIC Educational Resources Information Center

Felt, Andrew J.; Koelemay, Ryan; Richter, Alexander

2008-01-01

This article describes a method of flexible redistricting for K-12 public school districts that allows students from the same geographical region to be bused to different schools, with the goal of meeting average class size (ACS) target ranges. Results of a case study on a geographically large school district comparing this method to a traditional…

Sound Levels in East Texas Schools.

ERIC Educational Resources Information Center

Turner, Aaron Lynn

A survey of sound levels was taken in several Texas schools to determine the amount of noise and sound present by size of class, type of activity, location of building, and the presence of air conditioning and large amounts of glass. The data indicate that class size and relative amounts of glass have no significant bearing on the production of…

Class Size and Student Outcomes: Research and Policy Implications

ERIC Educational Resources Information Center

Chingos, Matthew M.

2013-01-01

Schools across the United States are facing budgetary pressures on a scale not seen in generations. Times of fiscal exigency force policymakers and education practitioners to pay more attention to the return on various categories of public investment in education. The sizes of the classes in which students are educated are often a focus of these…

40 CFR 113.4 - Size classes and associated liability limits for fixed onshore oil storage facilities, 1,000...

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 23 2012-07-01 2012-07-01 false Size classes and associated liability limits for fixed onshore oil storage facilities, 1,000 barrels or less capacity. 113.4 Section 113.4 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS LIABILITY LIMITS FOR...

40 CFR 113.4 - Size classes and associated liability limits for fixed onshore oil storage facilities, 1,000...

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 22 2014-07-01 2013-07-01 true Size classes and associated liability limits for fixed onshore oil storage facilities, 1,000 barrels or less capacity. 113.4 Section 113.4 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS LIABILITY LIMITS FOR...

A Comparison of QEIA and Non-QEIA Schools: Implications of Class Size Reduction

ERIC Educational Resources Information Center

Platt, Louise Carolyn Sater

2013-01-01

The purpose of this research study is to compare student achievement changes between matched QEIA and non-QEIA schools in an effort to infer effects of the most significant feature of QEIA funding, class size reduction. The study addressed the critical question--are there demonstrated, significant differences in student achievement gains between…

An Examination of Class Size Reduction on Teaching and Learning Processes: A Theoretical Perspective

ERIC Educational Resources Information Center

Harfitt, Gary James; Tsui, Amy B. M.

2015-01-01

The question of how class size impacts on student learning has been debated for some time, not least because it has substantial financial implications for educational policy. The strength of this debate notwithstanding, results from numerous international studies have been inconclusive. The study from which this paper stems sought to conceptualise…

Examine Middle School Students' Constructivist Environment Perceptions in Turkey: School Location and Class Size

ERIC Educational Resources Information Center

Yigit, Nevzat; Alpaslan, Muhammet Mustafa; Cinemre, Yasin; Balcin, Bilal

2017-01-01

This study aims to examine the middle school students' perceptions of the classroom learning environment in the science course in Turkey in terms of school location and class size. In the study the Assessing of Constructivist Learning Environment (ACLE) questionnaire was utilized to map students' perceptions of the classroom learning environment.…

What the Research Tells Us: Class Size Reduction. Information Capsule. Volume 1001

ERIC Educational Resources Information Center

Romanik, Dale

2010-01-01

This Information Capsule examines the background and history in addition to research findings pertaining to class size reduction (CSR). This Capsule concludes that although educational researchers have not definitively agreed upon the effectiveness of CSR, given its almost universal public appeal, there is little doubt it is here to stay in some…

Environmental characteristics and student physical activity in PE class: findings from two large urban areas of Texas.

PubMed

Skala, Katherine A; Springer, Andrew E; Sharma, Shreela V; Hoelscher, Deanna M; Kelder, Steven H

2012-05-01

Physical education (PE) classes provide opportunities for children to be active. This study examined the associations between specific environmental characteristics (teacher characteristics; class size, duration and location; and lesson context) and elementary school-aged children's moderate-to-vigorous activity (MVPA) during PE. Environmental characteristics and student activity levels were measured in 211 third-, fourth-, and fifth-grade PE classes in 74 Texas public schools using SOFIT direct observation. Students engaged in less than half their PE class time in MVPA (38%), while approximately 25% of class time was spent in classroom management. Percent time in MVPA was significantly higher in outdoor classes compared with indoors (41.4% vs. 36.1%, P = .037). Larger (P = .044) and longer (P = .001) classes were negatively associated with percentage of MVPA and positively correlated with time spent in management (P < .001). Findings suggest that children's activity may be influenced by environmental factors such as class size, location, and lesson contexts. These findings hold important policy implications for PE class organization and the need for strategies that maximize children's MVPA. Further research is needed to test the causal association of these factors with student MVPA.

What Doesn't Work for Whom? Exploring Heterogeneity in Responsiveness to the Family Check-Up in Early Childhood Using a Mixture Model Approach.

PubMed

Pelham, William E; Dishion, Thomas J; Tein, Jenn-Yun; Shaw, Daniel S; Wilson, Melvin N

2017-11-01

This study applied latent class analysis to a family-centered prevention trial in early childhood to identify subgroups of families with differential responsiveness to the Family Check-Up (FCU) intervention. The sample included 731 families with 2-year-olds randomized to the FCU or control condition and followed through age 5 with yearly follow-up assessments. A two-step mixture model was used to examine whether specific constellations of family characteristics at age 2 (baseline) were related to intervention response across ages 3, 4, and 5. The first step empirically identified latent classes of families based on several family risk and adjustment variables selected on the basis of previous research. The second step modeled the effect of the FCU on longitudinal change in children's problem behavior in each of the empirically derived latent classes. Results suggested a five-class solution, where a significant intervention effect of moderate to large size was observed in one of the five classes-the class characterized by child neglect, legal problems, and parental mental health issues. Pairwise comparisons revealed that the intervention effect was significantly greater in this class of families than in two other classes that were generally less at risk for the development of child disruptive behavior problems, albeit still low-income. Thus, findings suggest that (a) the FCU is most successful in reducing child problem behavior in more highly distressed, low-income families, and (b) the FCU may have little impact for relatively low-risk, low-income families. Future directions include the development of a brief screening process that can triage low-income families into groups that should be targeted for intervention, redirected to other services, monitored prospectively, or left alone.

Size-Independent Exciton Localization Efficiency in Colloidal CdSe/CdS Core/Crown Nanosheet Type-I Heterostructures.

PubMed

Li, Qiuyang; Wu, Kaifeng; Chen, Jinquan; Chen, Zheyuan; McBride, James R; Lian, Tianquan

2016-03-22

CdSe/CdS core/crown nanoplatelet type I heterostructures are a class of two-dimensional materials with atomically precise thickness and many potential optoelectronic applications. It remains unclear how the precise thickness and lack of energy disorder affect the properties of exciton transport in these materials. By steady-state photoluminescence excitation spectroscopy and ultrafast transient absorption spectroscopy, we show that in five CdSe/CdS core/crown structures with the same core and increasing crown size (with thickness of ∼1.8 nm, width of ∼11 nm, and length from 20 to 40 nm), the crown-to-core exciton localization efficiency is independent of crown size and increases with photon energy above the band edge (from 70% at 400 nm to ∼100% at 370 nm), while the localization time increases with the crown size. These observations can be understood by a model that accounts for the competition of in-plane exciton diffusion and selective hole trapping at the core/crown interface. Our findings suggest that the exciton localization efficiency can be further improved by reducing interfacial defects.

Parenting Stress among Low-Income and Working-Class Fathers: The Role of Employment

PubMed Central

Nomaguchi, Kei; Johnson, Wendi

2014-01-01

Contemporary norms of fatherhood emphasize the dual demands of breadwinning and daily involvement in childcare. Recent qualitative research suggests that working-class fathers find it difficult to meet these demands due to job instability and workplace inflexibility. Yet, little quantitative research has examined how employment characteristics are related to fathers’ parenting stress, in comparison with mothers’. Analyses using data from the Fragile Families and Child Wellbeing Study (N = 3,165) show that unemployment and workplace inflexibility, but not overwork, multiple jobs, odd-jobs, and nonstandard hours, are related to more parenting stress for fathers. Although these two factors are also related to more parenting stress for mothers, nuanced gender differences emerged: these are better predictors than other parental or child characteristics for fathers only, and the effect size of workplace inflexibility is greater for fathers than mothers. In sum, securing a job with flexible schedule is central to reducing fathers’ parenting stress. PMID:27616804

Green-noise halftoning with dot diffusion

NASA Astrophysics Data System (ADS)

Lippens, Stefaan; Philips, Wilfried

2007-02-01

Dot diffusion is a halftoning technique that is based on the traditional error diffusion concept, but offers a high degree of parallel processing by its block based approach. Traditional dot diffusion however suffers from periodicity artifacts. To limit the visibility of these artifacts, we propose grid diffusion, which applies different class matrices for different blocks. Furthermore, in this paper we will discuss two approaches in the dot diffusion framework to generate green-noise halftone patterns. The first approach is based on output dependent feedback (hysteresis), analogous to the standard green-noise error diffusion techniques. We observe that the resulting halftones are rather coarse and highly dependent on the used dot diffusion class matrices. In the second approach we don't limit the diffusion to the nearest neighbors. This leads to less coarse halftones, compared to the first approach. The drawback is that it can only cope with rather limited cluster sizes. We can reduce these drawbacks by combining the two approaches.

Parenting Stress among Low-Income and Working-Class Fathers: The Role of Employment.

PubMed

Nomaguchi, Kei; Johnson, Wendi

2016-08-01

Contemporary norms of fatherhood emphasize the dual demands of breadwinning and daily involvement in childcare. Recent qualitative research suggests that working-class fathers find it difficult to meet these demands due to job instability and workplace inflexibility. Yet, little quantitative research has examined how employment characteristics are related to fathers' parenting stress, in comparison with mothers'. Analyses using data from the Fragile Families and Child Wellbeing Study ( N = 3,165) show that unemployment and workplace inflexibility, but not overwork, multiple jobs, odd-jobs, and nonstandard hours, are related to more parenting stress for fathers. Although these two factors are also related to more parenting stress for mothers, nuanced gender differences emerged: these are better predictors than other parental or child characteristics for fathers only, and the effect size of workplace inflexibility is greater for fathers than mothers. In sum, securing a job with flexible schedule is central to reducing fathers' parenting stress.

Capitalizando en los cursos pequenos (Capitalizing on Small Class Size). ERIC Digest.

ERIC Educational Resources Information Center

O'Connell, Jessica; Smith, Stuart C.

This digest in Spanish examines school districts' efforts to reap the greatest benefit from smaller classes. Although the report discusses teaching strategies that are most effective in small classes, research has shown that teachers do not significantly change their teaching practices when they move from larger to smaller classes. Although…

The Effectiveness of learning materials based on multiple intelligence on the understanding of global warming

NASA Astrophysics Data System (ADS)

Liliawati, W.; Purwanto; Zulfikar, A.; Kamal, R. N.

2018-05-01

This study aims to examine the effectiveness of the use of teaching materials based on multiple intelligences on the understanding of high school students’ material on the theme of global warming. The research method used is static-group pretest-posttest design. Participants of the study were 60 high school students of XI class in one of the high schools in Bandung. Participants were divided into two classes of 30 students each for the experimental class and control class. The experimental class uses compound-based teaching materials while the experimental class does not use a compound intelligence-based teaching material. The instrument used is a test of understanding of the concept of global warming with multiple choices form amounted to 15 questions and 5 essay items. The test is given before and after it is applied to both classes. Data analysis using N-gain and effect size. The results obtained that the N-gain for both classes is in the medium category and the effectiveness of the use of teaching materials based on the results of effect-size test results obtained in the high category.

Soil erosion and effluent particle size distribution under different initial conditions and rock fragment coverage

NASA Astrophysics Data System (ADS)

Jomaa, S.; Barry, D. A.; Brovelli, A.; Heng, B. C. P.; Sander, G. C.; Parlange, J.-Y.

2012-04-01

It is well known that the presence of rock fragments on the soil surface and the soil's initial characteristics (moisture content, surface roughness, bulk density, etc.) are key factors influencing soil erosion dynamics and sediment delivery. In addition, the interaction of these factors increases the complexity of soil erosion patterns and makes predictions more difficult. The aim of this study was (i) to investigate the effect of soil initial conditions and rock fragment coverage on soil erosion yields and effluent particle size distribution and (ii) to evaluate to what extent the rock fragment coverage controls this relationship. Three laboratory flume experiments with constant precipitation rate of 74 mm/h on a loamy soil parcel with a 2% slope were performed. Experiments with duration of 2 h were conducted using the 6-m × 2-m EPFL erosion flume. During each experiment two conditions were considered, a bare soil and a rock fragment-protected (with 40% coverage) soil. The initial soil surface state was varied between the three experiments, from a freshly re-ploughed and almost dry condition to a compacted soil with a well-developed shield layer and high moisture content. Experiments were designed so that rain splash was the primary driver of soil erosion. Results showed that the amount of eroded mass was highly controlled by the initial soil conditions and whether the steady-state equilibrium was un-, partially- or fully- developed during the previous event. Additionally, results revealed that sediment yields and particle size composition in the initial part of an erosion event are more sensitive to the erosion history than the long-time behaviour. This latter appears to be mainly controlled by rainfall intensity. If steady-state was achieved for a previous event, then the next event consistently produced concentrations for each size class that peaked rapidly, and then declined gradually to steady-state equilibrium. If steady state was not obtained, then different and more complex behaviour was observed in the next event, with large differences found between fine, medium and coarse size classes. The presence of rock fragments on the topsoil reduced the time needed to reach steady state compared with the bare soil. This was attributed to the reduction of rain splash erosion caused by the rapid development of the overland flow, as a result of rock fragments reducing the flow cross-sectional area.

Macroscopic self-oscillations and aging transition in a network of synaptically coupled quadratic integrate-and-fire neurons.

PubMed

Ratas, Irmantas; Pyragas, Kestutis

2016-09-01

We analyze the dynamics of a large network of coupled quadratic integrate-and-fire neurons, which represent the canonical model for class I neurons near the spiking threshold. The network is heterogeneous in that it includes both inherently spiking and excitable neurons. The coupling is global via synapses that take into account the finite width of synaptic pulses. Using a recently developed reduction method based on the Lorentzian ansatz, we derive a closed system of equations for the neuron's firing rate and the mean membrane potential, which are exact in the infinite-size limit. The bifurcation analysis of the reduced equations reveals a rich scenario of asymptotic behavior, the most interesting of which is the macroscopic limit-cycle oscillations. It is shown that the finite width of synaptic pulses is a necessary condition for the existence of such oscillations. The robustness of the oscillations against aging damage, which transforms spiking neurons into nonspiking neurons, is analyzed. The validity of the reduced equations is confirmed by comparing their solutions with the solutions of microscopic equations for the finite-size networks.

Autonomous taxis could greatly reduce greenhouse-gas emissions of US light-duty vehicles

NASA Astrophysics Data System (ADS)

Greenblatt, Jeffery B.; Saxena, Samveg

2015-09-01

Autonomous vehicles (AVs) are conveyances to move passengers or freight without human intervention. AVs are potentially disruptive both technologically and socially, with claimed benefits including increased safety, road utilization, driver productivity and energy savings. Here we estimate 2014 and 2030 greenhouse-gas (GHG) emissions and costs of autonomous taxis (ATs), a class of fully autonomous shared AVs likely to gain rapid early market share, through three synergistic effects: (1) future decreases in electricity GHG emissions intensity, (2) smaller vehicle sizes resulting from trip-specific AT deployment, and (3) higher annual vehicle-miles travelled (VMT), increasing high-efficiency (especially battery-electric) vehicle cost-effectiveness. Combined, these factors could result in decreased US per-mile GHG emissions in 2030 per AT deployed of 87-94% below current conventionally driven vehicles (CDVs), and 63-82% below projected 2030 hybrid vehicles, without including other energy-saving benefits of AVs. With these substantial GHG savings, ATs could enable GHG reductions even if total VMT, average speed and vehicle size increased substantially. Oil consumption would also be reduced by nearly 100%.

Six-Degree-of-Freedom Trajectory Optimization Utilizing a Two-Timescale Collocation Architecture

NASA Technical Reports Server (NTRS)

Desai, Prasun N.; Conway, Bruce A.

2005-01-01

Six-degree-of-freedom (6DOF) trajectory optimization of a reentry vehicle is solved using a two-timescale collocation methodology. This class of 6DOF trajectory problems are characterized by two distinct timescales in their governing equations, where a subset of the states have high-frequency dynamics (the rotational equations of motion) while the remaining states (the translational equations of motion) vary comparatively slowly. With conventional collocation methods, the 6DOF problem size becomes extraordinarily large and difficult to solve. Utilizing the two-timescale collocation architecture, the problem size is reduced significantly. The converged solution shows a realistic landing profile and captures the appropriate high-frequency rotational dynamics. A large reduction in the overall problem size (by 55%) is attained with the two-timescale architecture as compared to the conventional single-timescale collocation method. Consequently, optimum 6DOF trajectory problems can now be solved efficiently using collocation, which was not previously possible for a system with two distinct timescales in the governing states.

Converting a Natural Protein Compartment into a Nanofactory for the Size-Constrained Synthesis of Antimicrobial Silver Nanoparticles.

PubMed

Giessen, Tobias W; Silver, Pamela A

2016-12-16

Engineered biological systems are used extensively for the production of high value and commodity organics. On the other hand, most inorganic nanomaterials are still synthesized via chemical routes. By engineering cellular compartments, functional nanoarchitectures can be produced under environmentally sustainable conditions. Encapsulins are a new class of microbial nanocompartments with promising applications in nanobiotechnology. Here, we engineer the Thermotoga maritima encapsulin EncTm to yield a designed compartment for the size-constrained synthesis of silver nanoparticles (Ag NPs). These Ag NPs exhibit uniform shape and size distributions as well as long-term stability. Ambient aqueous conditions can be used for Ag NP synthesis, while no reducing agents or solvents need to be added. The antimicrobial activity of the synthesized protein-coated or shell-free Ag NPs is superior to that of silver nitrate and citrate-capped Ag NPs. This study establishes encapsulins as an engineerable platform for the synthesis of biogenic functional nanomaterials.

Class Size and Teacher Load in High School English. New York State English Council Monography No. 8.

ERIC Educational Resources Information Center

Wade, Durlyn E.

To determine the class size and teaching load of secondary teachers of English in New York state, the Research Committee of the State English Council mailed 1,093 questionnaires to chairmen of English Departments in the state's registered public and private secondary schools. The 694 usable replies--representing 4,410 full-time English…

Review of "The Impact of a Universal Class-Size Reduction Policy: Evidence from Florida's Statewide Mandate"

ERIC Educational Resources Information Center

Finn, Jeremy D.

2010-01-01

In 2002, voters in Florida approved a constitutional amendment limiting class sizes in public schools to 18 students in the elementary grades, 22 students in middle grades, and 25 in high school grades. Analyzing statewide achievement data for school districts from 2004-2006 and for schools in 2007, this study purports to find that "mandated…

Factors in the Determination of Cost Effective Class Sizes. Report No. 009-79.

ERIC Educational Resources Information Center

Woods, Nancy A.

A system to determine cost effectiveness of class size should be based on both budgeted and actual expenditures and credit hours at the individual course section level. These two factors, in combination, are often expressed as cost per credit hour, and this statistic forms the primary means of evaluating planned "inputs" against actual "outputs."…

Understanding the Effect of Response Rate and Class Size Interaction on Students Evaluation of Teaching in a Higher Education

ERIC Educational Resources Information Center

Al Kuwaiti, Ahmed; AlQuraan, Mahmoud; Subbarayalu, Arun Vijay

2016-01-01

Objective: This study aims to investigate the interaction between response rate and class size and its effects on students' evaluation of instructors and the courses offered at a higher education Institution in Saudi Arabia. Study Design: A retrospective study design was chosen. Methods: One thousand four hundred and forty four different courses…

So How Big Is Big? Investigating the Impact of Class Size on Ratings in Student Evaluation

ERIC Educational Resources Information Center

Gannaway, Deanne; Green, Teegan; Mertova, Patricie

2018-01-01

Australian universities have a long history of use of student satisfaction surveys. Their use has expanded and purpose changed over time. The surveys are often viewed as distorted by external influences such as discipline context, class size and year level of participants. This paper reports on the results of a large-scale investigation…

Scaling Up: Faculty Workload, Class Size, and Student Satisfaction in a Distance Learning Course on Geographic Information Science.

ERIC Educational Resources Information Center

Dibiase, David; Rademacher, Henry J.

2005-01-01

This article explores issues of scalability and sustainability in distance learning. The authors kept detailed records of time they spent teaching a course in geographic information science via the World Wide Web over a six-month period, during which class sizes averaged 49 students. The authors also surveyed students' satisfaction with the…

The Impact of California's Class Size Reduction Initiative on Student Achievement: Detailed Findings from Eight School Districts.

ERIC Educational Resources Information Center

Mitchell, Douglas E.; Mitchell, Ross E.

This report presents a comprehensive preliminary analysis of how California's Class Size Reduction (CSR) initiative has impacted student achievement during the first 2 years of implementation. The analysis is based on complete student, classroom, and teacher records from 26,126 students in 1,174 classrooms from 83 schools in 8 Southern California…

Estimating accuracy of land-cover composition from two-stage cluster sampling

USGS Publications Warehouse

Stehman, S.V.; Wickham, J.D.; Fattorini, L.; Wade, T.D.; Baffetta, F.; Smith, J.H.

2009-01-01

Land-cover maps are often used to compute land-cover composition (i.e., the proportion or percent of area covered by each class), for each unit in a spatial partition of the region mapped. We derive design-based estimators of mean deviation (MD), mean absolute deviation (MAD), root mean square error (RMSE), and correlation (CORR) to quantify accuracy of land-cover composition for a general two-stage cluster sampling design, and for the special case of simple random sampling without replacement (SRSWOR) at each stage. The bias of the estimators for the two-stage SRSWOR design is evaluated via a simulation study. The estimators of RMSE and CORR have small bias except when sample size is small and the land-cover class is rare. The estimator of MAD is biased for both rare and common land-cover classes except when sample size is large. A general recommendation is that rare land-cover classes require large sample sizes to ensure that the accuracy estimators have small bias. ?? 2009 Elsevier Inc.

Computational techniques for flows with finite-rate condensation

NASA Technical Reports Server (NTRS)

Candler, Graham V.

1993-01-01

A computational method to simulate the inviscid two-dimensional flow of a two-phase fluid was developed. This computational technique treats the gas phase and each of a prescribed number of particle sizes as separate fluids which are allowed to interact with one another. Thus, each particle-size class is allowed to move through the fluid at its own velocity at each point in the flow field. Mass, momentum, and energy are exchanged between each particle class and the gas phase. It is assumed that the particles do not collide with one another, so that there is no inter-particle exchange of momentum and energy. However, the particles are allowed to grow, and therefore, they may change from one size class to another. Appropriate rates of mass, momentum, and energy exchange between the gas and particle phases and between the different particle classes were developed. A numerical method was developed for use with this equation set. Several test cases were computed and show qualitative agreement with previous calculations.

Does a Single Eigenstate Encode the Full Hamiltonian?

NASA Astrophysics Data System (ADS)

Garrison, James R.; Grover, Tarun

2018-04-01

The eigenstate thermalization hypothesis (ETH) posits that the reduced density matrix for a subsystem corresponding to an excited eigenstate is "thermal." Here we expound on this hypothesis by asking: For which class of operators, local or nonlocal, is ETH satisfied? We show that this question is directly related to a seemingly unrelated question: Is the Hamiltonian of a system encoded within a single eigenstate? We formulate a strong form of ETH where, in the thermodynamic limit, the reduced density matrix of a subsystem corresponding to a pure, finite energy density eigenstate asymptotically becomes equal to the thermal reduced density matrix, as long as the subsystem size is much less than the total system size, irrespective of how large the subsystem is compared to any intrinsic length scale of the system. This allows one to access the properties of the underlying Hamiltonian at arbitrary energy densities (or temperatures) using just a single eigenstate. We provide support for our conjecture by performing an exact diagonalization study of a nonintegrable 1D quantum lattice model with only energy conservation. In addition, we examine the case in which the subsystem size is a finite fraction of the total system size, and we find that, even in this case, many operators continue to match their canonical expectation values, at least approximately. In particular, the von Neumann entanglement entropy equals the thermal entropy as long as the subsystem is less than half the total system. Our results are consistent with the possibility that a single eigenstate correctly predicts the expectation values of all operators with support on less than half the total system, as long as one uses a microcanonical ensemble with vanishing energy width for comparison. We also study, both analytically and numerically, a particle-number conserving model at infinite temperature that substantiates our conjectures.

Single Atomic Iron Catalysts for Oxygen Reduction in Acidic Media: Particle Size Control and Thermal Activation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Hanguang; Hwang, Sooyeon; Wang, Maoyu

To significantly reduce the cost of proton exchange membrane (PEM) fuel cells, current Pt must be replaced by platinum-metal-group (PGM)-free catalysts for the oxygen reduction reaction (ORR) in acid. We report here a new class of high-performance atomic iron dispersed carbon catalysts through controlled chemical doping of iron ions into zinc-zeolitic imidazolate framework (ZIF), a type of metal-organic framework (MOF). The novel synthetic chemistry enables accurate size control of Fe-doped ZIF catalyst particles with a wide range from 20 to 1000 nm without changing chemical properties, which provides a great opportunity to increase the density of active sites that ismore » determined by the particle size. We elucidated the active site formation mechanism by correlating the chemical and structural changes with thermal activation process for the conversion from Fe-N4 complex containing hydrocarbon networks in ZIF to highly active FeNx sites embedded into carbon. A temperature of 800oC was identified as the critical point to start forming pyridinic nitrogen doping at the edge of the graphitized carbon planes. Further increasing heating temperature to 1100oC leads to increase of graphitic nitrogen, generating possible synergistic effect with FeNx sites to promote ORR activity. The best performing catalyst, which has well-defined particle size around 50 nm and abundance of atomic FeNx sites embedded into carbon structures, achieve a new performance milestone for the ORR in acid including a half-wave potential of 0.85 V vs RHE and only 20 mV loss after 10,000 cycles in O2 saturated H2SO4 electrolyte. The new class PGM-free catalyst with approaching activity to Pt holds great promise for future PEM fuel cells.« less

Antioxidants, mechanisms, and recovery by membrane processes.

PubMed

Bazinet, Laurent; Doyen, Alain

2017-03-04

Antioxidants molecules have a great interest for bio-food and nutraceutical industries since they play a vital role for their capacity to reduce oxidative processes. Consequently, these molecules, generally present in complex matrices, have to be fractionated and purified to characterize them and to test their antioxidant activity. However, as natural or synthetics antioxidant molecules differ in terms of structural composition and physico-chemical properties, appropriate separation technologies must be selected. Different fractionation technologies are available but the most commonly used are filtration processes. Indeed, these technologies allow fractionation according to molecular size (pressure-driven processes), charge, or both size and charge (electrically driven processes). In this context, and after summarizing the reaction mechanisms of the different classes and nature of antioxidants as well as membrane fractionation technologies, this manuscript presents the specific applications of these membranes processes for the recovery of antioxidant molecules.

No evidence of nonlinear effects of predator density, refuge availability, or body size of prey on prey mortality rates.

PubMed

Simkins, Richard M; Belk, Mark C

2017-08-01

Predator density, refuge availability, and body size of prey can all affect the mortality rate of prey. We assume that more predators will lead to an increase in prey mortality rate, but behavioral interactions between predators and prey, and availability of refuge, may lead to nonlinear effects of increased number of predators on prey mortality rates. We tested for nonlinear effects in prey mortality rates in a mesocosm experiment with different size classes of western mosquitofish ( Gambusia affinis ) as the prey, different numbers of green sunfish ( Lepomis cyanellus ) as the predators, and different levels of refuge. Predator number and size class of prey, but not refuge availability, had significant effects on the mortality rate of prey. Change in mortality rate of prey was linear and equal across the range of predator numbers. Each new predator increased the mortality rate by about 10% overall, and mortality rates were higher for smaller size classes. Predator-prey interactions at the individual level may not scale up to create nonlinearity in prey mortality rates with increasing predator density at the population level.

Disadvantaged Students in the Early Grades: Will Smaller Classes Help Them?

ERIC Educational Resources Information Center

Vaag Iversen, Jon Marius; Bonesrønning, Hans

2013-01-01

This paper uses data from the Norwegian elementary school to test whether students from disadvantaged backgrounds benefit from smaller classes. The data cover one cohort of fourth graders who have been treated in small versus large classes for a period of three years. The Norwegian class size rule of maximum 28 students is used to generate…

An Analysis of the Perceptions and Resources of Large University Classes

ERIC Educational Resources Information Center

Cash, Ceilidh Barlow; Letargo, Jessa; Graether, Steffen P.; Jacobs, Shoshanah R.

2017-01-01

Large class learning is a reality that is not exclusive to the first-year experience at midsized, comprehensive universities; upper-year courses have similarly high enrollment, with many class sizes greater than 200 students. Research into the efficacy and deficiencies of large undergraduate classes has been ongoing for more than 100 years, with…

78 FR 62785 - Self-Regulatory Organizations; Topaz Exchange, LLC; Notice of Filing and Immediate Effectiveness...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-22

... will automatically remove a market maker's quotes in all series of an options class when certain... on a class-by-class basis. These parameters are available for market maker quotes in single options... contracts executed by the market maker in an options class; (2) the percentage of the total size of the...

Intrinsic classes in the Union of European Football Associations soccer team ranking

NASA Astrophysics Data System (ADS)

Ausloos, Marcel

2014-11-01

A strong structural regularity of classes is found in soccer teams ranked by the Union of European Football Associations (UEFA) for the time interval 2009-2014. It concerns 424 to 453 teams according to the 5 competition seasons. The analysis is based on the rank-size theory considerations, the size being the UEFA coefficient at the end of a season. Three classes emerge: (i) the few "top" teams, (ii) 300 teams, (iii) the rest of the involved teams (about 150) in the tail of the distribution. There are marked empirical laws describing each class. A 3-parameter Lavalette function is used to describe the concave curving as the rank increases, and to distinguish the the tail from the central behavior.

Detecting representative data and generating synthetic samples to improve learning accuracy with imbalanced data sets.

PubMed

Li, Der-Chiang; Hu, Susan C; Lin, Liang-Sian; Yeh, Chun-Wu

2017-01-01

It is difficult for learning models to achieve high classification performances with imbalanced data sets, because with imbalanced data sets, when one of the classes is much larger than the others, most machine learning and data mining classifiers are overly influenced by the larger classes and ignore the smaller ones. As a result, the classification algorithms often have poor learning performances due to slow convergence in the smaller classes. To balance such data sets, this paper presents a strategy that involves reducing the sizes of the majority data and generating synthetic samples for the minority data. In the reducing operation, we use the box-and-whisker plot approach to exclude outliers and the Mega-Trend-Diffusion method to find representative data from the majority data. To generate the synthetic samples, we propose a counterintuitive hypothesis to find the distributed shape of the minority data, and then produce samples according to this distribution. Four real datasets were used to examine the performance of the proposed approach. We used paired t-tests to compare the Accuracy, G-mean, and F-measure scores of the proposed data pre-processing (PPDP) method merging in the D3C method (PPDP+D3C) with those of the one-sided selection (OSS), the well-known SMOTEBoost (SB) study, and the normal distribution-based oversampling (NDO) approach, and the proposed data pre-processing (PPDP) method. The results indicate that the classification performance of the proposed approach is better than that of above-mentioned methods.

Office of the Secretary of Defense Research, Development Test and Evaluation, Development and Test Evaluation, Defense, Director of Operational Test and Evaluation Defense, FY 1994 Budget Estimates, Justification of Estimates Submitted to Congress April 1993

DTIC Science & Technology

1993-04-01

separation capability. o Demonstrate advanced KKVs in the 6-20 KG weight class. o Test planning for SRAM/LEAP and PATRIOT/LEAP integrated technology...packaging techniques to reduce satellite size, weight , power, and total system costs. Further development of these technologies are absolutely 4...1993 o Developed a master plan with a delivery schedule for each light- weight subassembly in the sensor integration payload. o Finalized a contract for

Protection of large predators in a marine reserve alters size-dependent prey mortality

PubMed Central

Gaines, Steven D.; Hamilton, Scott L.; Warner, Robert R.

2017-01-01

Where predator–prey interactions are size-dependent, reductions in predator size owing to fishing has the potential to disrupt the ecological role of top predators in marine ecosystems. In southern California kelp forests, we investigated the size-dependence of the interaction between herbivorous sea urchins and one of their predators, California sheephead (Semicossyphus pulcher). Empirical tests examined how differences in predator size structure between reserve and fished areas affected size-specific urchin mortality. Sites inside marine reserves had greater sheephead size and biomass, while empirical feeding trials indicated that larger sheephead were required to successfully consume urchins of increasing test diameter. Evaluations of the selectivity of sheephead for two urchin species indicated that shorter-spined purple urchins were attacked more frequently and successfully than longer-spined red urchins of the same size class, particularly at the largest test diameters. As a result of these size-specific interactions and the higher biomass of large sheephead inside reserves, urchin mortality rates were three times higher inside the reserve for both species. In addition, urchin mortality rates decreased with urchin size, and very few large urchins were successfully consumed in fished areas. The truncation of sheephead size structure that commonly occurs owing to fishing will probably result in reductions in urchin mortality, which may reduce the resilience of kelp beds to urchin barren formation. By contrast, the recovery of predator size structure in marine reserves may restore this resilience, but may be delayed until fish grow to sizes capable of consuming larger urchins. PMID:28123086

Teachers and Group Size as Variables in Stimulating Oral Language Development with Grade One Disadvantaged Children. IMRID, Volume III, No. 1.

ERIC Educational Resources Information Center

Dunn, Lloyd M.; And Others

The purpose of this study was to evaluate both the relative effectiveness of different instructional personnel and the effect of differences in group size upon oral language acquisition for educationally disadvantaged first grade children. Involved in the treatment program were 23 classes in eight schools, all serving lower class areas of a…

Estimating live fuels for shrubs and herbs with BIOPAK.

Treesearch

Joseph E. Means; Olga N Krankina; Hao Jiang; Hongyan Li

1996-01-01

This paper describes use of BIOPAK to calculate size classes of live fuels for shrubs and herbs. A library of equations to estimate such fuels in the Pacific Northwest and northern Rocky Mountains is presented and used in an example. These methods can be used in other regions if the user first enters fuel size-class equations for a given region into a new library by...

A Study on the Learning Processes in Discrimination Shift Learning of Children with Mental Retardation: From the Point of Developmental View of "Logical Manipulation by Classification."

ERIC Educational Resources Information Center

Kanno, Atsushi

1989-01-01

The study was designed to investigate the learning processes in discrimination shift learning, in terms of developmental views of "logical manipulation by classification." Tasks comparing sizes of intradimensional value-classes and comparing sizes of interdimensional value-classes were devised in order to measure subjects' levels of…

Using Mobile Phone Technology in EFL Classes

ERIC Educational Resources Information Center

Sad, Süleyman Nihat

2008-01-01

Teachers of English as a foreign language (EFL) who want to develop successful lessons face numerous challenges, including large class sizes and inadequate instructional materials and technological support. Another problem is unmotivated students who refuse to participate in class activities. According to Harmer (2007), uncooperative and…

PSD-95 regulates synaptic kainate receptors at mouse hippocampal mossy fiber-CA3 synapses.

PubMed

Suzuki, Etsuko; Kamiya, Haruyuki

2016-06-01

Kainate-type glutamate receptors (KARs) are the third class of ionotropic glutamate receptors whose activation leads to the unique roles in regulating synaptic transmission and circuit functions. In contrast to AMPA receptors (AMPARs), little is known about the mechanism of synaptic localization of KARs. PSD-95, a major scaffold protein of the postsynaptic density, is a candidate molecule that regulates the synaptic KARs. Although PSD-95 was shown to bind directly to KARs subunits, it has not been tested whether PSD-95 regulates synaptic KARs in intact synapses. Using PSD-95 knockout mice, we directly investigated the role of PSD-95 in the KARs-mediated components of synaptic transmission at hippocampal mossy fiber-CA3 synapse, one of the synapses with the highest density of KARs. Mossy fiber EPSCs consist of AMPA receptor (AMPAR)-mediated fast component and KAR-mediated slower component, and the ratio was significantly reduced in PSD-95 knockout mice. The size of KARs-mediated field EPSP reduced in comparison with the size of the fiber volley. Analysis of KARs-mediated miniature EPSCs also suggested reduced synaptic KARs. All the evidence supports critical roles of PSD-95 in regulating synaptic KARs. Copyright © 2015 Elsevier Ireland Ltd and Japan Neuroscience Society. All rights reserved.

Shotgun mitogenomics across body size classes in a local assemblage of tropical Diptera: Phylogeny, species diversity and mitochondrial abundance spectrum.

PubMed

Choo, Le Qin; Crampton-Platt, Alex; Vogler, Alfried P

2017-10-01

Mitochondrial genomes can be assembled readily from shotgun-sequenced DNA mixtures of mass-trapped arthropods ("mitochondrial metagenomics"), speeding up the taxonomic characterization. Bulk sequencing was conducted on some 800 individuals of Diptera obtained by canopy fogging of a single tree in Borneo dominated by small (<1.5 mm) individuals. Specimens were split into five body size classes for DNA extraction, to equalize read numbers across specimens and to study how body size, a key ecological trait, interacts with species and phylogenetic diversity. Genome assembly produced 304 orthologous mitochondrial contigs presumed to each represent a different species. The small-bodied fraction was the by far most species-rich (187 contigs). Identification of contigs was through phylogenetic analysis together with 56 reference mitogenomes, which placed most of the Bornean community into seven clades of small-bodied species, indicating phylogenetic conservation of body size. Mapping of shotgun reads against the mitogenomes showed wide ranges of read abundances within each size class. Ranked read abundance plots were largely log-linear, indicating a uniformly filled abundance spectrum, especially for small-bodied species. Small-bodied species differed greatly from other size classes in neutral metacommunity parameters, exhibiting greater levels of immigration, besides greater total community size. We suggest that the established uses of mitochondrial metagenomics for analysis of species and phylogenetic diversity can be extended to parameterize recent theories of community ecology and biodiversity, and by focusing on the number mitochondria, rather than individuals, a new theoretical framework for analysis of mitochondrial abundance spectra can be developed that incorporates metabolic activity approximated by the count of mitochondria. © 2017 John Wiley & Sons Ltd.

Grain growth in Class I protostar Per-emb-50: a dust continuum analysis with NOEMA & SMA .

NASA Astrophysics Data System (ADS)

Agurto-Gangas, C.; Pineda, J. E.; Testi, L.; Caselli, P.; Szucs, L.; Tazzari, M.; Dunham, M.; Stephens, I. W.; Miotello, A.

A good understanding of when dust grains grow from sub-micrometer to millimeter sizes occurs is crucial for models of planet formation. This provides the first step towards the production of pebbles and planetesimals in protoplanetary disks. Thanks to detailed studies of the spectral index in Class II disks, it is well established that Class II objects have already dust grains of millimetres sizes, however, it is not clear when in the star formation process this grain growth occurs. Here, we present interferometric data from NOEMA at 3 mm and SMA at 1.3 mm of the Class I protostar, Per-emb-50, to determine the flux density spectral index at mm-wavelengths of the unresolved disk and the surrounding envelope. We find a spectral index in the unresolved disk 30% smaller than the envelope, alpha env=2.18, comparable to values obtained toward Class 0 sources.

Changes in Tree Reproductive Traits Reduce Functional Diversity in a Fragmented Atlantic Forest Landscape

PubMed Central

Girão, Luciana Coe; Lopes, Ariadna Valentina; Tabarelli, Marcelo; Bruna, Emilio M.

2007-01-01

Functional diversity has been postulated to be critical for the maintenance of ecosystem functioning, but the way it can be disrupted by human-related disturbances remains poorly investigated. Here we test the hypothesis that habitat fragmentation changes the relative contribution of tree species within categories of reproductive traits (frequency of traits) and reduces the functional diversity of tree assemblages. The study was carried out in an old and severely fragmented landscape of the Brazilian Atlantic forest. We used published information and field observations to obtain the frequency of tree species and individuals within 50 categories of reproductive traits (distributed in four major classes: pollination systems, floral biology, sexual systems, and reproductive systems) in 10 fragments and 10 tracts of forest interior (control plots). As hypothesized, populations in fragments and control plots differed substantially in the representation of the four major classes of reproductive traits (more than 50% of the categories investigated). The most conspicuous differences were the lack of three pollination systems in fragments-pollination by birds, flies and non-flying mammals-and that fragments had a higher frequency of both species and individuals pollinated by generalist vectors. Hermaphroditic species predominate in both habitats, although their relative abundances were higher in fragments. On the contrary, self-incompatible species were underrepresented in fragments. Moreover, fragments showed lower functional diversity (H' scores) for pollination systems (−30.3%), floral types (−23.6%), and floral sizes (−20.8%) in comparison to control plots. In contrast to the overwhelming effect of fragmentation, patch and landscape metrics such as patch size and forest cover played a minor role on the frequency of traits. Our results suggest that habitat fragmentation promotes a marked shift in the relative abundance of tree reproductive traits and greatly reduces the functional diversity of tree assemblages in fragmented landscapes. PMID:17878943

Spatial patterns of giant sequoia (Sequoiadendron giganteum) in two sequoia groves in Sequoia National Park, California

USGS Publications Warehouse

Stohlgren, Thomas J.

1993-01-01

Although Muir Grove and Castle Creek Grove are similar in area, elevation, and number of giant sequoias, various spatial pattern analysis techniques showed that they had dissimilar spatial patterns for similar-sized trees. Two-dimensional and transect two-term local quadrat variance techniques detected general trends in the spatial patterns of different-sized trees, detected multiple-scale patterns within individual size classes, and provided information on the scale and intensity of patches of individual size classes of trees in Muir and Castle Creek groves. In Muir Grove, midsized sequoias (1.5 to 2.4 m DBH classes) had major pattern scales 350–450 m in diameter, whereas the same-sized trees in Castle Creek Grove had pattern scales >1000 m in diameter. Many size classes of trees had minor patches superimposed on larger scale patterns in both groves. There may be different recruitment patterns in core (i.e., central) areas compared with peripheral areas of sequoia groves; core areas of both groves had more small live sequoias and dead sequoias than peripheral areas of the groves. Higher densities of sequoias and, perhaps, more rapid turnover of individuals in core areas may indicate (i) differences in disturbance histories and favorability of microsites in the core and peripheral areas of groves; (ii) different responses to disturbance due to shifts in the species composition of the stand and thus, the relative influences of intra- to inter-specific competition; or (iii) slower growth or lower survivorship rates in marginal habitat (i.e., peripheral areas).

Population biology of the mangrove crab Ucides cordatus (Decapoda: Ucididae) in an estuary from semiarid northeastern Brazil.

PubMed

Leite, Marcos de Miranda Leão; Rezende, Carla Ferreira; Silva, José Roberto Feitosa

2013-12-01

The mangrove crab Ucides cordatus is an important resource of estuarine regions along the Brazilian coast. U. cordatus is distributed from Florida, U.S.A., to the coast of Santa Catarina, Brazil. The species plays an important role in processing leaf litter in the mangroves, which optimizes the processes of energy transfer and nutrient cycling, and is considered a keystone species in the ecosystem. Population declines have been reported in different parts of the Brazilian coast. In the present study we evaluated aspects of the population structure, sex ratio and size at morphological sexual maturity. We analyzed 977 specimens collected monthly over 24 months (2010-2012), in a mangrove of the Jaguaribe River, in the municipality of Aracati on the East coast of Ceará state, Northeastern Brazil. The study area has a mild semiarid tropical climate, with mean temperatures between 26 and 28 degrees C. The area is located within the eco-region of the semiarid Northeast coast, where mangroves occur in small areas and estuaries are affected by mesomareal regimes. The population structure was evaluated by the frequency distribution of size classes in each month, and the overall sex ratio was analyzed using the chi-square test. Size at morphological sexual maturity was estimated based on the allometry of the cheliped of the males and the abdomen width of the females, using the program REGRANS. The size-frequency distribution was unimodal in both sexes. The overall sex ratio (M:F) (1:0.6) was significantly different from 1:1. Analysis of the sex ratio by size class showed that the proportion of males increased significantly from size class 55-60 mm upward, and this pattern persisted in the larger size classes. In the smaller size classes the sex ratio did not differ from 1:1. The size at morphological sexual maturity was estimated at a carapace width (CW) of 52 mm and 45 mm for males and females, respectively. Analysis of the population parameters indicated that the population of U. cordatus in the Jaguaribe River mangrove is stable. However, constant monitoring of the population is required to detect any changes in the population attributes that may affect this stability.

Exploratory analysis of osteoarthritis progression among medication users: data from the Osteoarthritis Initiative.

PubMed

Driban, Jeffrey B; Lo, Grace H; Eaton, Charles B; Lapane, Kate L; Nevitt, Michael; Harvey, William F; McCulloch, Charles E; McAlindon, Timothy E

2016-12-01

We conducted an exploratory analysis of osteoarthritis progression among medication users in the Osteoarthritis Initiative to identify interventions or pathways that may be associated with disease modification and therefore of interest for future clinical trials. We used participants from the Osteoarthritis Initiative with annual medication inventory data between the baseline and 36-month follow-up visit ( n = 2938). Consistent medication users were defined for each medication classification as a participant reporting at all four annual visits that they were regularly using an oral prescription medication at the time of the visit. The exploratory analysis focused on medication classes with 40 or more users. The primary outcome measures were medial tibiofemoral joint space width change and the Western Ontario and McMaster Universities Arthritis Index (WOMAC) knee pain score change (12-36-month visits). Within each knee, we explored eight comparisons between users and matched or unmatched nonusers (defined two ways). An effect size of each comparison was calculated. Medication classes had potential signals if (a) both knees had less progression among users compared with nonusers, or (b) there was less progression based on structure and symptoms in one knee. We screened 28 medication classes. Six medication classes had signals for fewer structural changes and better knee pain changes: alpha-adrenergic blockers, antilipemic (excluding statins and fibric acid), anticoagulants, selective serotonin reuptake inhibitors, antihistamines, and antineoplastic agents. Four medication classes had signals for structural changes alone: anti-estrogen (median effect size = 0.28; range = -0.41-0.64), angiotensin-converting enzyme inhibitors (median effect size = 0.13; range = -0.08-0.28), beta-adrenergic blockers (median effect size = 0.09; range = 0.01-0.30), and thyroid agents (median effect size = 0.04; range = -0.05-0.14). Thiazide diuretics had evidence for symptom modification (median effect size = -0.12; range = -0.24-0.04). Users of neurovascular, antilipemic, or hormonal interventions may have less disease progression compared with nonusers.

Adaptability of laser diffraction measurement technique in soil physics methodology

NASA Astrophysics Data System (ADS)

Barna, Gyöngyi; Szabó, József; Rajkai, Kálmán; Bakacsi, Zsófia; Koós, Sándor; László, Péter; Hauk, Gabriella; Makó, András

2016-04-01

There are intentions all around the world to harmonize soils' particle size distribution (PSD) data by the laser diffractometer measurements (LDM) to that of the sedimentation techniques (pipette or hydrometer methods). Unfortunately, up to the applied methodology (e. g. type of pre-treatments, kind of dispersant etc.), PSDs of the sedimentation methods (due to different standards) are dissimilar and could be hardly harmonized with each other, as well. A need was arisen therefore to build up a database, containing PSD values measured by the pipette method according to the Hungarian standard (MSZ-08. 0205: 1978) and the LDM according to a widespread and widely used procedure. In our current publication the first results of statistical analysis of the new and growing PSD database are presented: 204 soil samples measured with pipette method and LDM (Malvern Mastersizer 2000, HydroG dispersion unit) were compared. Applying usual size limits at the LDM, clay fraction was highly under- and silt fraction was overestimated compared to the pipette method. Subsequently soil texture classes determined from the LDM measurements significantly differ from results of the pipette method. According to previous surveys and relating to each other the two dataset to optimizing, the clay/silt boundary at LDM was changed. Comparing the results of PSDs by pipette method to that of the LDM, in case of clay and silt fractions the modified size limits gave higher similarities. Extension of upper size limit of clay fraction from 0.002 to 0.0066 mm, and so change the lower size limit of silt fractions causes more easy comparability of pipette method and LDM. Higher correlations were found between clay content and water vapor adsorption, specific surface area in case of modified limit, as well. Texture classes were also found less dissimilar. The difference between the results of the two kind of PSD measurement methods could be further reduced knowing other routinely analyzed soil parameters (e.g. pH(H2O), organic carbon and calcium carbonate content).

AN ASSESSMENT OF TYPEWRITING SKILLS IN THE SECONDARY SCHOOLS OF THE STATE OF UTAH IN RELATION TO JOB ENTRY REQUIREMENTS.

ERIC Educational Resources Information Center

PEHRSON, PATSY MAY

THE PURPOSE OF THIS STUDY WAS TO DETERMINE HOW MANY SEMESTERS OF TYPEWRITING SHOULD BE OFFERED TO AN ABLE STUDENT TO ATTAIN EMPLOYABLE SKILL. THE INFLUENCE OF THE FOLLOWING FACTORS ON TYPEWRITING ACHIEVEMENT WAS STUDIED--(1) STUDENT GRADE LEVEL, (2) CLASS SIZE, (3) SCHOOL SIZE, (4) LENGTH OF CLASS PERIOD, (5) USE OF MANUAL OR ELECTRIC TYPEWRITERS,…

Stocking, Forest Type, and Stand Size Class - The Southern Forest Inventory and Analysis Unit's Calculation of Three Important Stand Descriptors

Treesearch

Dennis M. May

1990-01-01

The procedures by which the Southern Forest Inventory and Analysis unit calculates stocking from tree data collected on inventory sample plots are described in this report. Stocking is then used to ascertain two other important stand descriptors: forest type and stand size class. Inventory data for three plots from the recently completed 1989 Tennessee survey are used...

What the Research Says about Class Size, Professional Development, and Recruitment, Induction, and Retention of Highly Qualified Teachers: A Compendium of the Evidence on Title II, Part A, Program-Funded Strategies

ERIC Educational Resources Information Center

Krasnoff, Basha

2015-01-01

States and districts have the flexibility to creatively use Title II, Part A funds to address teacher quality issues. Currently, three strategies predominate--class size reduction, professional development, and recruitment, induction, and retention of highly qualified teachers. Each strategy is implemented with the intention of improving teaching…

Abundance and Size Distribution of Cavity Trees in Second-Growth and Old-Growth Central Hardwood Forests

Treesearch

Zhaofei Fan; Stephen R. Shifley; Martin A. Spetich; Frank R. Thompson III; David R. Larsen

2005-01-01

In central hardwood forests, mean cavity-tree abundance increases with increasing standsize class (seedling/sapling, pole, sawtimber, old-growth). However, within a size class, the number of cavity trees is highly variable among 0.1-ha inventory plots. Plots in young stands are most likely to have no cavity trees, but some plots may have more than 50 cavity trees/ha....

Abundance and size distribution of cavity trees in second-growth and old-growth central hardwood forests

Treesearch

Zhaofei Fan; Stephen R. Shifley; Martin A. Spetich; Frank R. Thompson; David R. Larsen

2005-01-01

In central hardwood forests, mean cavity-tree abundance increases with increasing standsize class (seedling/sapling, pole, sawtimber, old-growth). However, within a size class, the number of cavity trees is highly variable among 0.1-ha inventory plots. Plots in young stands are most likely to have no cavity trees, but some plots may have more than 50 cavity trees/ha....

Estimating the quadratic mean diameters of fine woody debris in forests of the United States

Treesearch

Christopher W. Woodall; Vicente J. Monleon

2010-01-01

Most fine woody debris (FWD) line-intersect sampling protocols and associated estimators require an approximation of the quadratic mean diameter (QMD) of each individual FWD size class. There is a lack of empirically derived QMDs by FWD size class and species/forest type across the U.S. The objective of this study is to evaluate a technique known as the graphical...

Examining the Effect of Class Size on Classroom Engagement and Teacher-Pupil Interaction: Differences in Relation to Pupil Prior Attainment and Primary vs. Secondary Schools

ERIC Educational Resources Information Center

Blatchford, Peter; Bassett, Paul; Brown, Penelope

2011-01-01

It is widely recognized that we need to know more about effects of class size on classroom interactions and pupil behavior. This paper extends research by comparing effects on pupil classroom engagement and teacher-pupil interaction, and examining if effects vary by pupil attainment level and between primary and secondary schools. Systematic…

Use of alligator hole abundance and occupancy rate as indicators for restoration of a human-altered wetland

USGS Publications Warehouse

Fujisaki, Ikuko; Mazzotti, Frank J.; Hart, Kristen M.; Rice, Kenneth G.; Ogurcak, Danielle; Rochford, Michael; Jeffery, Brian M.; Brandt, Laura A.; Cherkiss, Michael S.

2012-01-01

Use of indicator species as a measure of ecosystem conditions is an established science application in environmental management. Because of its role in shaping wetland systems, the American alligator (Alligator mississippiensis) is one of the ecological indicators for wetland restoration in south Florida, USA. We conducted landscape-level aerial surveys of alligator holes in two different habitats in a wetland where anthropogenic modification of surface hydrology has altered the natural system. Alligator holes were scarcer in an area where modified hydrology caused draining and frequent dry-downs compared to another area that maintains a functional wetland system. Lower abundance of alligator holes indicates lack of alligator activities, lower overall species diversity, and lack of dry-season aquatic refugia for other organisms. The occupancy rate of alligator holes was lower than the current restoration target for the Everglades, and was variable by size class with large size-class alligators predominantly occupying alligator holes. This may indicate unequal size-class distribution, different habitat selection by size classes, or possibly a lack of recruitment. Our study provides pre-restoration baseline information about one indicator species for the Everglades. Success of the restoration can be assessed via effective synthesis of information derived by collective research efforts on the entire suite of selected ecological indicators.

Recent progress in half-Heusler thermoelectric materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Lihong; Zhang, Qinyong; Yuan, Bo

2016-04-15

Highlights: • Summarize the recent progress and advances in HH thermoelectric materials. • Preparing nanocomposites could reduce thermal conductivity. • Introducing enhance phonon scattering could further reduce the thermal conductivity. • Forming ternary systems to reducing the cost effectively. • The new class of HHs presents another opportunity to further optimize the HH system. - Abstract: Half-Heusler (HH) thermoelectric (TE) materials have been attracting extensive research interest over the last two decades, owing to their thermal stability, mechanical strength, and moderate ZT. This material system are potential candidates for medium to high temperature applications, which is close to the temperaturemore » range of most industrial waste heat sources. In this mini-review article, we briefly summarize the recent progress and advances in HH thermoelectric materials. Some effectively available approaches, such as HH nanocomposites to reduce thermal conductivity, using larger atomic mass and size differences to enhance phonon scattering to further reduce the thermal conductivity, forming ternary systems following the cost effective approach. In addition, new thermoelectric HH members are also discussed in this article, which points out that many new HH compounds may be possible for TE applications.« less

Class Extraction and Classification Accuracy in Latent Class Models

ERIC Educational Resources Information Center

Wu, Qiong

2009-01-01

Despite the increasing popularity of latent class models (LCM) in educational research, methodological studies have not yet accumulated much information on the appropriate application of this modeling technique, especially with regard to requirement on sample size and number of indicators. This dissertation study represented an initial attempt to…

Matrix models for size-structured populations: unrealistic fast growth or simply diffusion?

PubMed

Picard, Nicolas; Liang, Jingjing

2014-01-01

Matrix population models are widely used to study population dynamics but have been criticized because their outputs are sensitive to the dimension of the matrix (or, equivalently, to the class width). This sensitivity is concerning for the population growth rate (λ) because this is an intrinsic characteristic of the population that should not depend on the model specification. It has been suggested that the sensitivity of λ to matrix dimension was linked to the existence of fast pathways (i.e. the fraction of individuals that systematically move up a class), whose proportion increases when class width increases. We showed that for matrix population models with growth transition only from class i to class i + 1, λ was independent of the class width when the mortality and the recruitment rates were constant, irrespective of the growth rate. We also showed that if there were indeed fast pathways, there were also in about the same proportion slow pathways (i.e. the fraction of individuals that systematically remained in the same class), and that they jointly act as a diffusion process (where diffusion here is the movement in size of an individual whose size increments are random according to a normal distribution with mean zero). For 53 tree species from a tropical rain forest in the Central African Republic, the diffusion resulting from common matrix dimensions was much stronger than would be realistic. Yet, the sensitivity of λ to matrix dimension for a class width in the range 1-10 cm was small, much smaller than the sampling uncertainty on the value of λ. Moreover, λ could either increase or decrease when class width increased depending on the species. Overall, even if the class width should be kept small enough to limit diffusion, it had little impact on the estimate of λ for tree species.

Temperature-Correlated Changes in Phytoplankton Community Structure Are Restricted to Polar Waters.

PubMed

Ward, Ben A

2015-01-01

Globally distributed observations of size-fractionated chlorophyll a and temperature were used to incorporate temperature dependence into an existing semi-empirical model of phytoplankton community size structure. The additional temperature-dependent term significantly increased the model's ability to both reproduce and predict observations of chlorophyll a size-fractionation at temperatures below 2°C. The most notable improvements were in the smallest (picoplankton) size-class, for which overall model fit was more than doubled, and predictive skill was increased by approximately 40%. The model was subsequently applied to generate global maps for three phytoplankton size classes, on the basis of satellite-derived estimates of surface chlorophyll a and sea surface temperature. Polar waters were associated with marked decline in the chlorophyll a biomass of the smallest cells, relative to lower latitude waters of equivalent total chlorophyll a. In the same regions a complementary increase was seen in the chlorophyll a biomass of larger size classes. These findings suggest that a warming and stratifying ocean will see a poleward expansion of the habitat range of the smallest phytoplankton, with the possible displacement of some larger groups that currently dominate. There was no evidence of a strong temperature dependence in tropical or sub-tropical regions, suggesting that future direct temperature effects on community structure at lower latitudes may be small.

How long does a mindfulness-based stress reduction program need to be? A review of class contact hours and effect sizes for psychological distress.

PubMed

Carmody, James; Baer, Ruth A

2009-06-01

The mindfulness-based stress reduction (MBSR) program was designed to be long enough for participants to grasp the principles of self-regulation through mindfulness and develop skill and autonomy in mindfulness practice. It traditionally consists of 26 hours of session time including eight classes of 2-1/2 hours and an all-day class. The circumstances of some groups exclude them from participating in this standard form and a number of trials have evaluated programs with abbreviated class time. If lower program time demands can lead to similar outcomes in psychological functioning, it would support their utility in these settings and might lead to greater participation. However, the effect of variation in class hours on outcomes has not been systematically studied. To obtain preliminary information related to this question we examined effect sizes for psychological outcome variables in published studies of MBSR, some of which had adapted the standard number of class hours. The correlation between mean effect size and number of in-class hours was nonsignificant for both clinical and nonclinical samples and suggests that adaptations that include less class time may be worthwhile for populations for whom reduction of psychological distress is an important goal and for whom longer time commitment may be a barrier to their ability or willingness to participate. However, the standard MBSR format has accrued the most empirical support for its efficacy and session time may be important to the development of other kinds of program outcomes. The result points to the importance of empirical studies systematically examining this question. Copyright 2009 Wiley Periodicals, Inc.

Aggregate distribution and associated organic carbon influenced by cover crops

NASA Astrophysics Data System (ADS)

Barquero, Irene; García-González, Irene; Benito, Marta; Gabriel, Jose Luis; Quemada, Miguel; Hontoria, Chiquinquirá

2013-04-01

Replacing fallow with cover crops during the non-cropping period seems to be a good alternative to diminish soil degradation by enhancing soil aggregation and increasing organic carbon. The aim of this study was to analyze the effect of replacing fallow by different winter cover crops (CC) on the aggregate distribution and C associated of an Haplic Calcisol. The study area was located in Central Spain, under semi-arid Mediterranean climate. A 4-year field trial was conducted using Barley (Hordeum vulgare L.) and Vetch (Vicia sativa L.) as CC during the intercropping period of maize (Zea mays L.) under irrigation. All treatments were equally irrigated and fertilized. Maize was directly sown over CC residues previously killed in early spring. Composite samples were collected at 0-5 and 5-20 cm depths in each treatment on autumn of 2010. Soil samples were separated by wet sieving into four aggregate-size classes: large macroaggregates ( >2000 µm); small macroaggregates (250-2000 µm); microaggregates (53-250 µm); and < 53 µm (silt + clay size). Organic carbon associated to each aggregate-size class was measured by Walkley-Black Method. Our preliminary results showed that the aggregate-size distribution was dominated by microaggregates (48-53%) and the <53 µm fraction (40-44%) resulting in a low mean weight diameter (MWD). Both cover crops increased aggregate size resulting in a higher MWD (0.28 mm) in comparison with fallow (0.20 mm) in the 0-5 cm layer. Barley showed a higher MWD than fallow also in 5-20 cm layer. Organic carbon concentrations in aggregate-size classes at top layer followed the order: large macroaggregates > small macroaggregates > microaggregates > silt + clay size. Treatments did not influence C concentration in aggregate-size classes. In conclusion, cover crops improved soil structure increasing the proportion of macroaggregates and MWD being Barley more effective than Vetch at subsurface layer.

Fishing and temperature effects on the size structure of exploited fish stocks.

PubMed

Tu, Chen-Yi; Chen, Kuan-Ting; Hsieh, Chih-Hao

2018-05-08

Size structure of fish stock plays an important role in maintaining sustainability of the population. Size distribution of an exploited stock is predicted to shift toward small individuals caused by size-selective fishing and/or warming; however, their relative contribution remains relatively unexplored. In addition, existing analyses on size structure have focused on univariate size-based indicators (SBIs), such as mean length, evenness of size classes, or the upper 95-percentile of the length frequency distribution; these approaches may not capture full information of size structure. To bridge the gap, we used the variation partitioning approach to examine how the size structure (composition of size classes) responded to fishing, warming and the interaction. We analyzed 28 exploited stocks in the West US, Alaska and North Sea. Our result shows fishing has the most prominent effect on the size structure of the exploited stocks. In addition, the fish stocks experienced higher variability in fishing is more responsive to the temperature effect in their size structure, suggesting that fishing may elevate the sensitivity of exploited stocks in responding to environmental effects. The variation partitioning approach provides complementary information to univariate SBIs in analyzing size structure.

Achievement Flourishes in Larger Classes: Secondary School Students in Most Countries Achieved Better Literacy in Larger Classes

ERIC Educational Resources Information Center

Alharbi, Abeer A.; Stoet, Gijsbert

2017-01-01

There is no consensus among academics about whether children benefit from smaller classes. We analysed the data from the 2012 Programme for International Student Assessment (PISA) to test if smaller classes lead to higher performance. Advantages of using this data set are not only its size (478,120 15-year old students in 63 nations) and…

Ecological effects of particulate matter.

PubMed

Grantz, D A; Garner, J H B; Johnson, D W

2003-06-01

Atmospheric particulate matter (PM) is a heterogeneous material. Though regulated as un-speciated mass, it exerts most effects on vegetation and ecosystems by virtue of the mass loading of its chemical constituents. As this varies temporally and spatially, prediction of regional impacts remains difficult. Deposition of PM to vegetated surfaces depends on the size distribution of the particles and, to a lesser extent, on the chemistry. However, chemical loading of an ecosystem may be determined by the size distribution as different constituents dominate different size fractions. Coating with dust may cause abrasion and radiative heating, and may reduce the photosynthetically active photon flux reaching the photosynthetic tissues. Acidic and alkaline materials may cause leaf surface injury while other materials may be taken up across the cuticle. A more likely route for metabolic uptake and impact on vegetation and ecosystems is through the rhizosphere. PM deposited directly to the soil can influence nutrient cycling, especially that of nitrogen, through its effects on the rhizosphere bacteria and fungi. Alkaline cation and aluminum availability are dependent upon the pH of the soil that may be altered dramatically by deposition of various classes of PM. A regional effect of PM on ecosystems is linked to climate change. Increased PM may reduce radiation interception by plant canopies and may reduce precipitation through a variety of physical effects. At the present time, evidence does not support large regional threats due to un-speciated PM, though site-specific and constituent-specific effects can be readily identified. Interactions of PM with other pollutants and with components of climate change remain important areas of research in assessment of challenges to ecosystem stability.

Entanglement entropy of 2D conformal quantum critical points: hearing the shape of a quantum drum.

PubMed

Fradkin, Eduardo; Moore, Joel E

2006-08-04

The entanglement entropy of a pure quantum state of a bipartite system A union or logical sumB is defined as the von Neumann entropy of the reduced density matrix obtained by tracing over one of the two parts. In one dimension, the entanglement of critical ground states diverges logarithmically in the subsystem size, with a universal coefficient that for conformally invariant critical points is related to the central charge of the conformal field theory. We find that the entanglement entropy of a standard class of z=2 conformal quantum critical points in two spatial dimensions, in addition to a nonuniversal "area law" contribution linear in the size of the AB boundary, generically has a universal logarithmically divergent correction, which is completely determined by the geometry of the partition and by the central charge of the field theory that describes the critical wave function.

Deicing and Anti-Icing Unite

NASA Technical Reports Server (NTRS)

2002-01-01

With funding from Glenn's Small Business Innovation Research (SBIR) program, Cox & Company, Inc., built an ice protection system that combines thermal anti-icing and mechanical deicing to keep airfoils (wings and other lifting surfaces) clear of ice. Cox's concept was to combine an anti-icing system with NASA's Electro-Mechanical Expulsion Deicing System, a mechanical deicer. The anti-icing element of this hybrid would reduce the aerodynamic losses associated with deicing systems. The Cox Low Power Ice Protection System is the first new aircraft ice protection system that has been approved by the Federal Aviation Administration for use on a business jet in 40 years. While the system is currently sized for Premier class aircraft, there are no apparent constraints prohibiting its use on aircraft of any size. The company is investigating further applications, such as adapting the system for unmanned aerial vehicles and other military aircraft.

Class Sizes and Dissadvantaged Schools.

ERIC Educational Resources Information Center

Warner, David

1978-01-01

Describes a program in which smaller class groups for socially and culturally deprived children resulted in enhanced social attitudes and more responsive, mature behavior in interaction with both adults and peers. (Author/IRT)

Asteroid Airbursts: Risk Assessment and Reduction

NASA Astrophysics Data System (ADS)

Boslough, M.

2015-12-01

Airbursts are events in which small (meters to tens-of-meters in diameter) asteroids deposit most of their energy in the atmosphere with a total energy greater than small nuclear explosions (>0.1 kilotons of TNT). The airburst risk is higher than previous assessments for two reasons. First, they are more frequent than previously thought. The Tunguska-class (~40 meters) population estimate has doubled, and Chelyabinsk-class (~20 meters) has increased by a factor of 2.6. Second, asteroid airbursts are significantly more damaging than previously assumed. In most cases, they more efficiently couple energy to the surface than nuclear explosions of the same yield. Past Near-Earth Object (NEO) risk assessments concluded that the largest asteroids (> 1 km) dominated the hazard. Large NEOs represent only a tiny fraction of the population but the potential for global catastrophe means that the contribution from low-probability, high-consequence events is large. Nearly 90% of these objects, none of which is on a collision course, have been catalogued. This has reduced their assessed near-term statistical risk by more than an order of magnitude because completion is highest for the largest and most dangerous. The relative risk from small objects would therefore be increasing even if their absolute assessed risk were not. Uncertainty in the number of small NEOs remains large and can only be reduced by expanded surveys. One strategy would be to count small NEOs making close passes in statistically significant numbers. For example, there are about 25 times as many objects of a given size that pass within the distance of geosynchronous orbit than collide with the earth, and 2000 times as many pass within a lunar distance (accounting for gravitational focusing). An asteroid the size of the Chelyabinsk impactor (~20 m) could potentially be observed within geosynchronous orbit every two years and within lunar orbit nearly once a week. A Tunguska-sized asteroid (~40 m) passes within a lunar distance several times a year. A survey optimized to discover and count these objects would rapidly reduce the uncertainty in their populations. An additional benefit would be early warning of an imminent impact to give authorities time to issue evacuation or take-cover instructions in circumstances for which there would be no time the prevent an impact.

Sensitivity Analysis of the USLE Soil Erodibility Factor to Its Determining Parameters

NASA Astrophysics Data System (ADS)

Mitova, Milena; Rousseva, Svetla

2014-05-01

Soil erosion is recognized as one of the most serious soil threats worldwide. Soil erosion prediction is the first step in soil conservation planning. The Universal Soil Loss Equation (USLE) is one of the most widely used models for soil erosion predictions. One of the five USLE predictors is the soil erodibility factor (K-factor), which evaluates the impact of soil characteristics on soil erosion rates. Soil erodibility nomograph defines K-factor depending on soil characteristics, such as: particle size distribution (fractions finer that 0.002 mm and from 0.1 to 0.002 mm), organic matter content, soil structure and soil profile water permeability. Identifying the soil characteristics, which mostly influence the K-factor would give an opportunity to control the soil loss through erosion by controlling the parameters, which reduce the K-factor value. The aim of the report is to present the results of analysis of the relative weight of these soil characteristics in the K-factor values. The relative impact of the soil characteristics on K-factor was studied through a series of statistical analyses of data from the geographic database for soil erosion risk assessments in Bulgaria. Degree of correlation between K-factor values and the parameters that determine it was studied by correlation analysis. The sensitivity of the K-factor was determined by studying the variance of each parameter within the range between minimum and maximum possible values considering average value of the other factors. Normalizing transformation of data sets was applied because of the different dimensions and the orders of variation of the values of the various parameters. The results show that the content of particles finer than 0.002 mm has the most significant relative impact on the soil erodibility, followed by the content of particles with size from 0.1 mm to 0.002 mm, the class of the water permeability of the soil profile, the content of organic matter and the aggregation class. The relationships of the K-factor with the relative content of particle size from 0.1 to 0.002 mm and the class of aggregation are linear, directly proportional. When the content of particles sized from 0.1 to 0.002 mm increases with one relative unit, the K-factor increases with 0.0091 t ha h / ha MJ mm, while the same relative increase of the class of aggregation, results to an increase of the K-factor by 0.0034 t ha h / ha MJ mm. On the other side, the relationships between the K-factor values and the contents of clay and organic matter, and the class of profile water permeability, are linear, inversely proportional. When the clay content increases with one relative unit, the K-factor value decreases by 0.0099 t ha h / ha MJ mm. The same relative increases in the content of soil organic matter and the class of soil profile water permeability, result to a decrease of the values of K-factor respectively by 0.0042 and 0.0045 t ha h / ha MJ mm.

Transitions in Smokers' Social Networks After Quit Attempts: A Latent Transition Analysis.

PubMed

Bray, Bethany C; Smith, Rachel A; Piper, Megan E; Roberts, Linda J; Baker, Timothy B

2016-12-01

Smokers' social networks vary in size, composition, and amount of exposure to smoking. The extent to which smokers' social networks change after a quit attempt is unknown, as is the relation between quitting success and later network changes. Unique types of social networks for 691 smokers enrolled in a smoking-cessation trial were identified based on network size, new network members, members' smoking habits, within network smoking, smoking buddies, and romantic partners' smoking. Latent transition analysis was used to identify the network classes and to predict transitions in class membership across 3 years from biochemically assessed smoking abstinence. Five network classes were identified: Immersed (large network, extensive smoking exposure including smoking buddies), Low Smoking Exposure (large network, minimal smoking exposure), Smoking Partner (small network, smoking exposure primarily from partner), Isolated (small network, minimal smoking exposure), and Distant Smoking Exposure (small network, considerable nonpartner smoking exposure). Abstinence at years 1 and 2 was associated with shifts in participants' social networks to less contact with smokers and larger networks in years 2 and 3. In the years following a smoking-cessation attempt, smokers' social networks changed, and abstinence status predicted these changes. Networks defined by high levels of exposure to smokers were especially associated with continued smoking. Abstinence, however, predicted transitions to larger social networks comprising less smoking exposure. These results support treatments that aim to reduce exposure to smoking cues and smokers, including partners who smoke. Prior research has shown that social network features predict the likelihood of subsequent smoking cessation. The current research illustrates how successful quitting predicts social network change over 3 years following a quit attempt. Specifically, abstinence predicts transitions to networks that are larger and afford less exposure to smokers. This suggests that quitting smoking may expand a person's social milieu rather than narrow it. This effect, plus reduced exposure to smokers, may help sustain abstinence. © The Author 2016. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Study of effect of variables on particle size of telmisartan nanosuspensions using box-Behnken design.

PubMed

Rao, M R P; Bajaj, A

2014-12-01

Telmisartan, an orally active nonpeptide angiotensin II receptor antagonist is a BCS Class II drug having aqueous solubility of 9.9 µg/ml and hence oral bioavailability of 40%. The present study involved preparation of nanosuspensions by evaporative antisolvent precipitation technique to improve the saturation solubility and dissolution rate of telmisartan. Various stabilizers such as TPGS, PVPK 30, PEG 6000 were investigated of which TPGS was found to provide maximum decrease in particle size and accord greater stability to the nanosuspensions. Box-Behnken design was used to investigate the effect of independent variables like stabilizer concentration, time and speed of stirring on particle size of nanosuspensions. Pharmacodynamic studies using Goldblatt technique were undertaken to evaluate the effect of nano-sizing on the hypotensive effect of the drug. Concentration of TPGS and speed of rotation were found to play an important role in particle size of the nanosuspensions whereas time of stirring displayed an exponential relationship with particle size. Freeze dried nanocrystals obtained from nanosuspension of least particle size were found to have increased saturation solubility of telmisartan in different dissolution media. The reconstituted nanosuspension was found to reduce both systolic and diastolic blood pressure without affecting pulse pressure and heart rate. Statistical tools can be used to identify key process and formulation parameters which play a significant role in controlling the particle size in nanosuspensions. © Georg Thieme Verlag KG Stuttgart · New York.

Measurement of variation in soil solute tracer concentration across a range of effective pore sizes

USGS Publications Warehouse

Harvey, Judson W.

1993-01-01

Solute transport concepts in soil are based on speculation that solutes are distributed nonuniformly within large and small pores. Solute concentrations have not previously been measured across a range of pore sizes and examined in relation to soil hydrological properties. For this study, modified pressure cells were used to measure variation in concentration of a solute tracer across a range of pore sizes. Intact cores were removed from the site of a field tracer experiment, and soil water was eluted from 10 or more discrete classes of pore size. Simultaneous changes in water content and unsaturated hydraulic conductivity were determined on cores using standard pressure cell techniques. Bromide tracer concentration varied by as much as 100% across the range of pore sizes sampled. Immediately following application of the bromide tracer on field plots, bromide was most concentrated in the largest pores; concentrations were lower in pores of progressively smaller sizes. After 27 days, bromide was most dilute in the largest pores and concentrations were higher in the smaller pores. A sharp, threefold decrease in specific water capacity during elution indicated separation of two major pore size classes at a pressure of 47 cm H2O and a corresponding effective pore diameter of 70 μm. Variation in tracer concentration, on the other hand, was spread across the entire range of pore sizes investigated in this study. A two-porosity characterization of the transport domain, based on water retention criteria, only broadly characterized the pattern of variation in tracer concentration across pore size classes during transport through a macroporous soil.

Novel orally active growth hormone secretagogues.

PubMed

Hansen, T K; Ankersen, M; Hansen, B S; Raun, K; Nielsen, K K; Lau, J; Peschke, B; Lundt, B F; Thøgersen, H; Johansen, N L; Madsen, K; Andersen, P H

1998-09-10

A novel class of growth hormone-releasing compounds with a molecular weight in the range from 500 to 650 has been discovered. The aim of this study was to obtain growth hormone secretagogues with oral bioavailability. By a rational approach we were able to reduce the size of the lead compound ipamorelin (4) and simultaneously to reduce hydrogen-bonding potential by incorporation of backbone isosters while retaining in vivo potency in swine. A rat pituitary assay was used for screening of all compounds and to evaluate which compounds should be tested further for in vivo potency in swine and oral bioavailability, fpo, in dogs. Most of the tested compounds had fpo in the range of 10-55%. In vivo potency in swine after iv dosing is reported, and ED50 was found to be 30 nmol/kg of body weight for the most potent compound.

Heart period variability and psychopathology in urban boys at risk for delinquency.

PubMed

Pine, D S; Wasserman, G A; Miller, L; Coplan, J D; Bagiella, E; Kovelenku, P; Myers, M M; Sloan, R P

1998-09-01

To examine associations between heart period variability (HPV) and psychopathology in young urban boys at risk for delinquency, a series of 697-11-year-old younger brothers of adjudicated delinquents received a standardized psychiatric evaluation and an assessment of heart period variability (HPV). Psychiatric symptoms were rated in two domains: externalizing and internalizing psychopathology. Continuous measures of both externalizing and internalizing psychopathology were associated with reductions in HPV components related to parasympathetic activity. These associations could not be explained by a number of potentially confounding variables, such as age, ethnicity, social class, body size, or family history of hypertension. Although familial hypertension predicted reduced HPV and externalizing psychopathology, associations between externalizing psychopathology and HPV were independent of familial hypertension. Psychiatric symptoms are associated with reduced HPV in young urban boys at risk for delinquency.

The relationship of blue crab (Callinectes sapidus) size class and molt stage to disease acquisition and intensity of Hematodinium perezi infections.

PubMed

Lycett, Kristen A; Chung, J Sook; Pitula, Joseph S

2018-01-01

In the blue crab, Callinectes sapidus, early studies suggested a relationship between smaller crabs, which molt more frequently, and higher rates of infection by the dinoflagellate parasite, Hematodinium perezi. In order to better explore the influence of size and molting on infections, blue crabs were collected from the Maryland coastal bays and screened for the presence of H. perezi in hemolymph samples using a quantitative PCR assay. Molt stage was determined by a radioimmunoassay which measured ecdysteroid concentrations in blue crab hemolymph. Differences were seen in infection prevalence between size classes, with the medium size class (crabs 61 to 90 mm carapace width) and juvenile crabs (≤ 30 mm carapace width) having the highest infection prevalence at 47.2% and 46.7%, respectively. All size classes were susceptible to infection, although fall months favored disease acquisition by juveniles, whereas mid-sized animals (31-90 mm carapace width) acquired infection predominantly in summer. Disease intensity was also most pronounced in the summer, with blue crabs > 61 mm being primary sources of proliferation. Molt status appeared to be influenced by infection, with infected crabs having significantly lower concentrations of ecdysteroids than uninfected crabs in the spring and the fall. We hypothesize that infection by H. perezi may increase molt intervals, with a delay in the spring molt cycle as an evolutionary adaptation functioning to coincide with increased host metabolism, providing optimal conditions for H. perezi propagation. Regardless of season, postmolt crabs harbored significantly higher proportions of moderate and heavy infections, suggesting that the process of ecdysis, and the postmolt recovery period, has a positive effect on parasite proliferation.

A 15-year randomized controlled study of a reduced shrinkage stress resin composite.

PubMed

van Dijken, Jan W V; Lindberg, Anders

2015-09-01

The aim of this randomized controlled study was to evaluate the long term effectiveness of a reduced shrinkage stress resin composite in Class II restorations. The material was compared intra-individually with a microhybrid resin composite. Each of 50 patients with at least one pair of two similar sized Class II cavities participated (22 female, 28 male, mean age 43 years, range 18-64). Each participant received in each pair, in a randomized way, one Class II restoration performed with a reduced shrinkage stress resin composite (InTen-S) and the other restoration with a microhybrid resin composite restoration (Point 4). Both restorations were placed with an etch-and-rinse bonding system and an oblique layering technique. A total of 106 restorations, 33 premolar and 73 molars, were placed. The restorations were evaluated blindly each year using modified USPHS criteria. The overall performance of the experimental restorations was tested after intra-individual comparison using the Friedmańs two-way analysis of variance test. The hypothesis was rejected at the 5% level. At 15 years, 91 restorations were evaluated. The drop out frequency was 15 restorations (5 male, 3 female participants; 2 premolar and 13 molar restorations). Except for 2 participants, who reported slight symptoms during a few weeks after placement, no post-operative sensitivity was observed at the recalls. The overall success rate at 15 years was 77%. Twenty-one non acceptable restorations were observed during the 15 years follow up, 10 InTen-S (21.7%) and 11 Point 4 (24.4%) restorations (p>0.05). Annual failure rates for the resin composites were 1.5% and 1.6%, respectively. The main reasons for failure were secondary caries (8) and resin composite fracture (7). The differences between premolar vs. molar restorations and between restorations in male vs. female participants were not significant. Significant differences were observed between 2-surface vs. 3-surface restorations. During the 15-year follow up, the reduced shrinkage stress resin composite showed a good clinical durability in Class II cavities, but not significantly better than the control microhybrid resin composite. Secondary caries and material fracture were the main reasons of failure. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Crown-root morphology of lower incisors in patients with class III malocclusion.

PubMed

Wang, Bo; Shen, Guofang; Fang, Bing; Zhang, Li

2012-07-01

The purpose of this study was to investigate the crown-root morphology of lower incisors in patients with class III malocclusion using cone-beam computed tomography. Cone-beam computed tomography images were analyzed from 53 adult class I patients (group 1), 37 preadolescent class III patients (group 2), and 66 adult class III patients (group 3) comprising 3 divisions (divisions 1, 2, and 3 corresponded to mild, moderate, and severe class III malocclusions). The size and crown-root angulations of lower incisors in different groups and divisions were statistically appraised with group 1 used as the control group. No significant differences were found for the size of lower incisors among different groups and divisions (P > 0.05). Compared with group 1, the crown-root angulations of lower incisors in groups 2 and 3 were significantly larger (P < 0.01), and among 3 divisions, the lower incisors of division 3 rather than divisions 2 and 3 exhibited larger crown-root angulations (P < 0.01). Attention should be paid to the enlarged crown-root angulations of lower incisors in class III patients during orthodontic and orthognathic treatment, especially in severe ones.

Digital image processing of nanometer-size metal particles on amorphous substrates

NASA Technical Reports Server (NTRS)

Soria, F.; Artal, P.; Bescos, J.; Heinemann, K.

1989-01-01

The task of differentiating very small metal aggregates supported on amorphous films from the phase contrast image features inherently stemming from the support is extremely difficult in the nanometer particle size range. Digital image processing was employed to overcome some of the ambiguities in evaluating such micrographs. It was demonstrated that such processing allowed positive particle detection and a limited degree of statistical size analysis even for micrographs where by bare eye examination the distribution between particles and erroneous substrate features would seem highly ambiguous. The smallest size class detected for Pd/C samples peaks at 0.8 nm. This size class was found in various samples prepared under different evaporation conditions and it is concluded that these particles consist of 'a magic number' of 13 atoms and have cubooctahedral or icosahedral crystal structure.

Student Achievement in Large-Lecture Remedial Math Classes

ERIC Educational Resources Information Center

Monte, Brent M.

2011-01-01

Due to the increase in students seeking remedial math classes at the community college level, coupled with declining revenues to the community colleges and a lack of classroom availability, the need to consider increasing class size has become a relevant and timely issue. This study is a mixed-method, quasi-experimental study testing effects of…

76 FR 32257 - Small Business Size Standards; Waiver of the Nonmanufacturer Rule

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-03

... AGENCY: U.S. Small Business Administration. ACTION: Notice of proposed retraction of a Class Waiver from...: The U.S. Small Business Administration (SBA) is proposing the retraction of a class waiver from the... retraction of the class waiver from the Nonmanufacturer Rule for PSC 9130 (Liquid Propellants--Petroleum Base...

Big Class Size Challenges: Teaching Reading in Primary Classes in Kampala, Uganda's Central Municipality

ERIC Educational Resources Information Center

Kewaza, Samuel; Welch, Myrtle I.

2013-01-01

Research on reading has established that reading is a pivotal discipline and early literacy development dictates later reading success. Therefore, the purpose of this study is to investigate challenges encountered with reading pedagogy, teaching materials, and teachers' attitudes towards teaching reading in crowded primary classes in Kampala,…

An algorithm for spatial heirarchy clustering

NASA Technical Reports Server (NTRS)

Dejesusparada, N. (Principal Investigator); Velasco, F. R. D.

1981-01-01

A method for utilizing both spectral and spatial redundancy in compacting and preclassifying images is presented. In multispectral satellite images, a high correlation exists between neighboring image points which tend to occupy dense and restricted regions of the feature space. The image is divided into windows of the same size where the clustering is made. The classes obtained in several neighboring windows are clustered, and then again successively clustered until only one region corresponding to the whole image is obtained. By employing this algorithm only a few points are considered in each clustering, thus reducing computational effort. The method is illustrated as applied to LANDSAT images.

Heat exchangers in regenerative gas turbine cycles

NASA Astrophysics Data System (ADS)

Nina, M. N. R.; Aguas, M. P. N.

1985-09-01

Advances in compact heat exchanger design and fabrication together with fuel cost rises continuously improve the attractability of regenerative gas turbine helicopter engines. In this study cycle parameters aiming at reduced specific fuel consumption and increased payload or mission range, have been optimized together with heat exchanger type and size. The discussion is based on a typical mission for an attack helicopter in the 900 kw power class. A range of heat exchangers is studied to define the most favorable geometry in terms of lower fuel consumption and minimum engine plus fuel weight. Heat exchanger volume, frontal area ratio and pressure drop effect on cycle efficiency are considered.

Varying Radii of On-Axis Anode Hollows For kJ-Class Dense Plasma Focus

NASA Astrophysics Data System (ADS)

Shaw, Brian; Chapman, Steven; Falabella, Steven; Pankin, Alexei; Liu, Jason; Link, Anthony; Schmidt, Andréa

2017-10-01

A dense plasma focus (DPF) is a compact plasma gun that produces high energy ion beams, up to several MeV, through strong potential gradients. Motivated by particle-in-cell simulations, we have tried a series of hollow anodes on our kJ-class DPF. Each anode has varying hollow sizes, and has been studied to optimize ion beam production in Helium, reduce anode sputter, and increase neutron yields in deuterium. We diagnose the rate at which electrode material is ablated and deposited onto nearby surfaces. This is of interest in the case of solid targets, which perform poorly in the presence of sputter. We have found that the larger the hollow radius produces more energetic ion beams, higher neutron yield, and sputter less than a flat top anode. A complete comparison is presented. This work was prepared by LLNL under Contract DE-AC52-07NA27344 and supported by Office of Defense Nuclear Nonproliferation Research and Development within U.S. Department of Energy's National Nuclear Security Administration.

Model reduction by trimming for a class of semi-Markov reliability models and the corresponding error bound

NASA Technical Reports Server (NTRS)

White, Allan L.; Palumbo, Daniel L.

1991-01-01

Semi-Markov processes have proved to be an effective and convenient tool to construct models of systems that achieve reliability by redundancy and reconfiguration. These models are able to depict complex system architectures and to capture the dynamics of fault arrival and system recovery. A disadvantage of this approach is that the models can be extremely large, which poses both a model and a computational problem. Techniques are needed to reduce the model size. Because these systems are used in critical applications where failure can be expensive, there must be an analytically derived bound for the error produced by the model reduction technique. A model reduction technique called trimming is presented that can be applied to a popular class of systems. Automatic model generation programs were written to help the reliability analyst produce models of complex systems. This method, trimming, is easy to implement and the error bound easy to compute. Hence, the method lends itself to inclusion in an automatic model generator.

Ectomycorrhizal ecology is imprinted in the genome of the dominant symbiotic fungus Cenococcum geophilum

PubMed Central

Peter, Martina; Kohler, Annegret; Ohm, Robin A.; Kuo, Alan; Krützmann, Jennifer; Morin, Emmanuelle; Arend, Matthias; Barry, Kerrie W.; Binder, Manfred; Choi, Cindy; Clum, Alicia; Copeland, Alex; Grisel, Nadine; Haridas, Sajeet; Kipfer, Tabea; LaButti, Kurt; Lindquist, Erika; Lipzen, Anna; Maire, Renaud; Meier, Barbara; Mihaltcheva, Sirma; Molinier, Virginie; Murat, Claude; Pöggeler, Stefanie; Quandt, C. Alisha; Sperisen, Christoph; Tritt, Andrew; Tisserant, Emilie; Crous, Pedro W.; Henrissat, Bernard; Nehls, Uwe; Egli, Simon; Spatafora, Joseph W.; Grigoriev, Igor V.; Martin, Francis M.

2016-01-01

The most frequently encountered symbiont on tree roots is the ascomycete Cenococcum geophilum, the only mycorrhizal species within the largest fungal class Dothideomycetes, a class known for devastating plant pathogens. Here we show that the symbiotic genomic idiosyncrasies of ectomycorrhizal basidiomycetes are also present in C. geophilum with symbiosis-induced, taxon-specific genes of unknown function and reduced numbers of plant cell wall-degrading enzymes. C. geophilum still holds a significant set of genes in categories known to be involved in pathogenesis and shows an increased genome size due to transposable elements proliferation. Transcript profiling revealed a striking upregulation of membrane transporters, including aquaporin water channels and sugar transporters, and mycorrhiza-induced small secreted proteins (MiSSPs) in ectomycorrhiza compared with free-living mycelium. The frequency with which this symbiont is found on tree roots and its possible role in water and nutrient transport in symbiosis calls for further studies on mechanisms of host and environmental adaptation. PMID:27601008

An analysis of spectral envelope-reduction via quadratic assignment problems

NASA Technical Reports Server (NTRS)

George, Alan; Pothen, Alex

1994-01-01

A new spectral algorithm for reordering a sparse symmetric matrix to reduce its envelope size was described. The ordering is computed by associating a Laplacian matrix with the given matrix and then sorting the components of a specified eigenvector of the Laplacian. In this paper, we provide an analysis of the spectral envelope reduction algorithm. We described related 1- and 2-sum problems; the former is related to the envelope size, while the latter is related to an upper bound on the work involved in an envelope Cholesky factorization scheme. We formulate the latter two problems as quadratic assignment problems, and then study the 2-sum problem in more detail. We obtain lower bounds on the 2-sum by considering a projected quadratic assignment problem, and then show that finding a permutation matrix closest to an orthogonal matrix attaining one of the lower bounds justifies the spectral envelope reduction algorithm. The lower bound on the 2-sum is seen to be tight for reasonably 'uniform' finite element meshes. We also obtain asymptotically tight lower bounds for the envelope size for certain classes of meshes.

Fourier spatial frequency analysis for image classification: training the training set

NASA Astrophysics Data System (ADS)

Johnson, Timothy H.; Lhamo, Yigah; Shi, Lingyan; Alfano, Robert R.; Russell, Stewart

2016-04-01

The Directional Fourier Spatial Frequencies (DFSF) of a 2D image can identify similarity in spatial patterns within groups of related images. A Support Vector Machine (SVM) can then be used to classify images if the inter-image variance of the FSF in the training set is bounded. However, if variation in FSF increases with training set size, accuracy may decrease as the size of the training set increases. This calls for a method to identify a set of training images from among the originals that can form a vector basis for the entire class. Applying the Cauchy product method we extract the DFSF spectrum from radiographs of osteoporotic bone, and use it as a matched filter set to eliminate noise and image specific frequencies, and demonstrate that selection of a subset of superclassifiers from within a set of training images improves SVM accuracy. Central to this challenge is that the size of the search space can become computationally prohibitive for all but the smallest training sets. We are investigating methods to reduce the search space to identify an optimal subset of basis training images.

The Casalbuoni-Brink-Schwarz superparticle with covariant, reducible constraints

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dayi, O.F.

1992-04-30

This paper discusses the fermionic constraints of the massless Casalbuoni-Brink-Schwarz superparticle in d = 10 which are separated covariantly as first- and second-class constraints which are infinitely reducible. Although the reducibility conditions of the second-class constraints include the first-class ones a consistent quantization is possible. The ghost structure of the system for quantizing it in terms of the BFV-BRST methods is given and unitarity is shown.

Size-dependent selective mechanisms on males and females and the evolution of sexual size dimorphism in frogs.

PubMed

Nali, Renato C; Zamudio, Kelly R; Haddad, Célio F B; Prado, Cynthia P A

2014-12-01

Sexual size dimorphism (SSD) varies in animals from male biased to female biased. The evolution of SSD is potentially influenced by a number of factors, such as territoriality, fecundity, and temporal breeding patterns (explosive vs. prolonged). In general, frogs show female-biased SSD with broad variance among species. Using comparative methods, we examine how different selective forces affect male and female sizes, and we test hypotheses about size-dependent mechanisms shaping SSD in frogs. Male size was weakly associated with SSD in all size classes, and we found no significant association among SSD, male size, temporal breeding pattern, and male territoriality. In contrast, female size best explained SSD variation across all size classes but especially for small-bodied species. We found a stronger evolutionary association between female body size and fecundity, and this fecundity advantage was highest in explosively breeding species. Our data indicate that the fecundity advantage associated with female body size may not be linear, such that intermediate and large females benefit less with body size increases. Therefore, size-dependent selection in females associated with fecundity and breeding patterns is an important mechanism driving SSD evolution in frogs. Our study underscores the fact that lineage-specific ecology and behavior should be incorporated in comparative analyses of animal SSD.

Predicting the recruitment of established regeneration into the sapling size class following partial cutting in the Acadian Forest Region: Using long-term observations to assess the performance of FVS-NE

Treesearch

David Ray; Chad Keyser; Robert Seymour; John Brissette

2008-01-01

Forest managers are increasingly called upon to provide long-term predictions of forest development. The dynamics of regeneration establishment, survival and subsequent recruitment of established seedlings to larger size classes is a critical component of these forecasts, yet remains a weak link in available models. To test the reliability of FVS-NE for simulating...

Plant-mediated effects on extracellular enzyme activities in distinct soil aggregate size classes in field

NASA Astrophysics Data System (ADS)

Kumar, Amit; Dorodnikov, Maxim; Splettstößer, Thomas; Kuzyakov, Yakov; Pausch, Johanna

2017-04-01

Soil aggregation and microbial activities within the aggregates are important factors regulating soil carbon (C) turnover. A reliable and sensitive proxy for microbial activity is activity of extracellular enzymes (EEA). In the present study, effects of soil aggregates on EEA were investigated under three maize plant densities (Low, Normal, and High). Bulk soil was fractionated into three aggregate size classes (>2000 µm large macroaggregates; 2000-250 µm small macroaggregates; <250 µm microaggregates) by optimal-moisture sieving. Microbial biomass and EEA (β-1,4-glucosidase (BG), β-1,4-N-acetylglucosaminidase (NAG), L-leucine aminopeptidase (LAP) and acid phosphatase (acP)) catalyzing soil organic matter (SOM) decomposition were measured in rooted soil of maize and soil from bare fallow. Microbial biomass C (Cmic) decreased with decreasing aggregate size classes. Potential and specific EEA (per unit of Cmic) increased from macro- to microaggregates. In comparison with bare fallow soil, specific EEA of microaggregates in rooted soil was higher by up to 73%, 31%, 26%, and 92% for BG, NAG, acP and LAP, respectively. Moreover, high plant density decreased macroaggregates by 9% compared to bare fallow. Enhanced EEA in three aggregate size classes demonstrated activation of microorganisms by roots. Strong EEA in microaggregates can be explained by microaggregates' localization within the soil. Originally adhering to surfaces of macroaggregates, microaggregates were preferentially exposed to C substrates and nutrients, thereby promoting microbial activity.

Population biology and feeding habits of the nephropid lobster Metanephrops thomsoni (Bate, 1888) in the East China Sea.

PubMed

Choi, Jung Hwa; Kim, Jung Nyun; Kim, Mi Hyang; Chang, Dae Soo; Yoo, Joon Taek; Kim, Jin Koo

2008-07-01

Population biology and feeding habits of the nephropidlobsterMetanephrops thomsoni (Bate) was studied from a field survey sampled with bottom trawls in the East China Sea. The female/male ratio was 1.06:1. Three size-class groups were discriminated for both sexes, which may correspond to one to three year-old cohorts. The average stage fecundity was 471 in each brood. Larger than two-year-size-class females are multi broods during the breeding season. Gut analysis showed that this lobster is a common camivore and mainly consume crustaceans and fishes, regardless of sex and carapace length size.

75 FR 28077 - Small Business Size Standards: Waiver of the Nonmanufacturer Rule

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-19

... class waiver of the Nonmanufacturer Rule for Improved Outer Tactical Vests and related accessories under... Class Waiver for Improved Outer Tactical Vests, PSC 8470, NAICS code 339113, Federal Register Notice...

Purification and Characterization of Enzymes from Yeast: An Extended Undergraduate Laboratory Sequence for Large Classes

ERIC Educational Resources Information Center

Johanson, Kelly E.; Watt, Terry J.; McIntyre, Neil R.; Thompson, Marleesa

2013-01-01

Providing a project-based experience in an undergraduate biochemistry laboratory class can be complex with large class sizes and limited resources. We have designed a 6-week curriculum during which students purify and characterize the enzymes invertase and phosphatase from bakers yeast. Purification is performed in two stages via ethanol…

Student Response Systems and Facilitating the Large Lecture Basic Communication Course: Assessing Engagement and Learning

ERIC Educational Resources Information Center

Denker, Katherine J.

2013-01-01

Instructors of large lecture classes face a variety of challenges, including student engagement and participation. With budget cuts and increasing class sizes, more schools may turn to large lecture/lab formats for the basic communication course (Stanley & Porter, 2002); instructors must understand how these classes engage students. One viable…

Evaluating the Benefits of Providing Archived Online Lectures to In-Class Math Students

ERIC Educational Resources Information Center

Cascaval, Radu C.; Fogler, Kethera A.; Abrams, Gene D.; Durham, Robert L.

2008-01-01

The present study examines the impact of a novel online video lecture archiving system on in-class students enrolled in traditional math courses at a mid-sized, primarily undergraduate, university in the West. The archiving system allows in-class students web access to complete video recordings of the actual classroom lectures, and sometimes of…

Empirical study of seven data mining algorithms on different characteristics of datasets for biomedical classification applications.

PubMed

Zhang, Yiyan; Xin, Yi; Li, Qin; Ma, Jianshe; Li, Shuai; Lv, Xiaodan; Lv, Weiqi

2017-11-02

Various kinds of data mining algorithms are continuously raised with the development of related disciplines. The applicable scopes and their performances of these algorithms are different. Hence, finding a suitable algorithm for a dataset is becoming an important emphasis for biomedical researchers to solve practical problems promptly. In this paper, seven kinds of sophisticated active algorithms, namely, C4.5, support vector machine, AdaBoost, k-nearest neighbor, naïve Bayes, random forest, and logistic regression, were selected as the research objects. The seven algorithms were applied to the 12 top-click UCI public datasets with the task of classification, and their performances were compared through induction and analysis. The sample size, number of attributes, number of missing values, and the sample size of each class, correlation coefficients between variables, class entropy of task variable, and the ratio of the sample size of the largest class to the least class were calculated to character the 12 research datasets. The two ensemble algorithms reach high accuracy of classification on most datasets. Moreover, random forest performs better than AdaBoost on the unbalanced dataset of the multi-class task. Simple algorithms, such as the naïve Bayes and logistic regression model are suitable for a small dataset with high correlation between the task and other non-task attribute variables. K-nearest neighbor and C4.5 decision tree algorithms perform well on binary- and multi-class task datasets. Support vector machine is more adept on the balanced small dataset of the binary-class task. No algorithm can maintain the best performance in all datasets. The applicability of the seven data mining algorithms on the datasets with different characteristics was summarized to provide a reference for biomedical researchers or beginners in different fields.

The oxidoreductase ERp57 efficiently reduces partially folded in preference to fully folded MHC class I molecules

PubMed Central

Antoniou, Antony N.; Ford, Stuart; Alphey, Magnus; Osborne, Andrew; Elliott, Tim; Powis, Simon J.

2002-01-01

The oxidoreductase ERp57 is an integral component of the peptide loading complex of major histocompatibility complex (MHC) class I molecules, formed during their chaperone-assisted assembly in the endoplasmic reticulum. Misfolded MHC class I molecules or those denied suitable peptides are retrotranslocated and degraded in the cytosol. The presence of ERp57 during class I assembly suggests it may be involved in the reduction of intrachain disulfides prior to retrotranslocation. We have studied the ability of ERp57 to reduce MHC class I molecules in vitro. Recombinant ERp57 specifically reduced partially folded MHC class I molecules, whereas it had little or no effect on folded and peptide-loaded MHC class I molecules. Reductase activity was associated with cysteines at positions 56 and 405 of ERp57, the N-terminal residues of the active CXXC motifs. Our data suggest that the reductase activity of ERp57 may be involved during the unfolding of MHC class I molecules, leading to targeting for degradation. PMID:12032078

The energy consumption and cost savings of truck electrification for heavy duty vocational applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Zhiming; Lin, Zhenhong; Franzese, Oscar

This paper evaluates the application of battery electric vehicles (BEVs) and genset plug-in hybrid electric vehicles (PHEVs) to Class-7 local delivery trucks and genset PHEV for Class-8 utility bucket trucks over widely real-world driving data performed by conventional heavy-duty trucks. A simulation tool based on vehicle tractive energy methodology and component efficiency for addressing component and system performance was developed to evaluate the energy consumption and performance of the trucks. As part of this analysis, various battery sizes combined with different charging powers on the E-Trucks for local delivery and utility bucket applications were investigated. The results show that themore » E-Truck applications not only reduce energy consumption but also achieve significant energy cost savings. For delivery E-Trucks, the results show that periodic stops at delivery sites provide sufficient time for battery charging, and for this reason, a high-power charger is not necessary. For utility bucket PHEV trucks, energy consumption per mile of bucket truck operation is typically higher because of longer idling times and extra high idling load associated with heavy utility work. The availability of on-route charging is typically lacking at the work sites of bucket trucks; hence, the battery size of these trucks is somewhat larger than that of the delivery trucks studied.« less

Extending a prototype knowledge- and object-based image analysis model to coarser spatial resolution imagery: an example from the Missouri River

USGS Publications Warehouse

Strong, Laurence L.

2012-01-01

A prototype knowledge- and object-based image analysis model was developed to inventory and map least tern and piping plover habitat on the Missouri River, USA. The model has been used to inventory the state of sandbars annually for 4 segments of the Missouri River since 2006 using QuickBird imagery. Interpretation of the state of sandbars is difficult when images for the segment are acquired at different river stages and different states of vegetation phenology and canopy cover. Concurrent QuickBird and RapidEye images were classified using the model and the spatial correspondence of classes in the land cover and sandbar maps were analysed for the spatial extent of the images and at nest locations for both bird species. Omission and commission errors were low for unvegetated land cover classes used for nesting by both bird species and for land cover types with continuous vegetation cover and water. Errors were larger for land cover classes characterized by a mixture of sand and vegetation. Sandbar classification decisions are made using information on land cover class proportions and disagreement between sandbar classes was resolved using fuzzy membership possibilities. Regression analysis of area for a paired sample of 47 sandbars indicated an average positive bias, 1.15 ha, for RapidEye that did not vary with sandbar size. RapidEye has potential to reduce temporal uncertainty about least tern and piping plover habitat but would not be suitable for mapping sandbar erosion, and characterization of sandbar shapes or vegetation patches at fine spatial resolution.

Extending a prototype knowledge and object based image analysis model to coarser spatial resolution imagery: an example from the Missouri River

USGS Publications Warehouse

Strong, Laurence L.

2012-01-01

A prototype knowledge- and object-based image analysis model was developed to inventory and map least tern and piping plover habitat on the Missouri River, USA. The model has been used to inventory the state of sandbars annually for 4 segments of the Missouri River since 2006 using QuickBird imagery. Interpretation of the state of sandbars is difficult when images for the segment are acquired at different river stages and different states of vegetation phenology and canopy cover. Concurrent QuickBird and RapidEye images were classified using the model and the spatial correspondence of classes in the land cover and sandbar maps were analysed for the spatial extent of the images and at nest locations for both bird species. Omission and commission errors were low for unvegetated land cover classes used for nesting by both bird species and for land cover types with continuous vegetation cover and water. Errors were larger for land cover classes characterized by a mixture of sand and vegetation. Sandbar classification decisions are made using information on land cover class proportions and disagreement between sandbar classes was resolved using fuzzy membership possibilities. Regression analysis of area for a paired sample of 47 sandbars indicated an average positive bias, 1.15 ha, for RapidEye that did not vary with sandbar size. RapidEye has potential to reduce temporal uncertainty about least tern and piping plover habitat but would not be suitable for mapping sandbar erosion, and characterization of sandbar shapes or vegetation patches at fine spatial resolution.

Development of population structure and spatial distribution patterns of a restored forest during 17-year succession (1993-2010) in Pingshuo opencast mine spoil, China.

PubMed

Zhao, Zhongqiu; Wang, Lianhua; Bai, Zhongke; Pan, Ziguan; Wang, Yun

2015-07-01

Afforestation of native tree species is often recommended for ecological restoration in mining areas, but the understanding of the ecological processes of restored vegetation is quite limited. In order to provide insight of the ecological processes of restored vegetation, in this study, we investigate the development of the population structure and spatial distribution patterns of restored Robinia pseudoacacia (ROPS) and Pinus tabuliformis (PITA) mixed forests during the 17 years of the mine spoil period of the Pingshuo opencast mine, Shanxi Province, China. After a 17-year succession, apart from the two planted species, Ulmus pumila (ULPU), as an invasive species, settled in the plot along with a large number of small diameter at breast height (DBH) size. In total, there are 10,062 living individual plants, much more than that at the plantation (5105), and ROPS had become the dominant species with a section area with a breast height of 9.40 m(2) hm(-2) and a mean DBH of 6.72 cm, much higher than both PITA and ULPU. The DBH size classes of all the total species showed inverted J-shaped distributions, which may have been a result of the large number of small regenerated ULPU trees. The DBH size classes of both ROPS and PITA showed peak-type structures with individuals mainly gathering in the moderate DBH size class, indicating a relatively healthy DBH size class structure. Meanwhile, invasive ULPU were distributed in a clear L shape, concentrating on the small DBH size class, indicating a relatively low survival rate for adult trees. Both ROPS and PITA species survival in the plantation showed uniform and aggregated distribution at small scales and random with scales increasing. ULPU showed a strong aggregation at small scales as well as random with scales increasing. Both the population structure and spatial distribution indicated that ROPS dominates and will continue to dominate the community in the future succession, which should be continuously monitored.

Variation in size frequency distribution of coral populations under different fishing pressures in two contrasting locations in the Indian Ocean.

PubMed

Grimsditch, G; Pisapia, C; Huck, M; Karisa, J; Obura, D; Sweet, M

2017-10-01

This study aimed to assess how the size-frequency distributions of coral genera varied between reefs under different fishing pressures in two contrasting Indian Ocean locations (the Maldives and East Africa). Using generalized linear mixed models, we were able to demonstrate that complex interactions occurred between coral genera, coral size class and fishing pressure. In both locations, we found Acropora coral species to be more abundant in non-fished compared to fished sites (a pattern which was consistent for nearly all the assessed size classes). Coral genera classified as 'stress tolerant' showed a contrasting pattern i.e. were higher in abundance in fished compared to non-fished sites. Site specific variations were also observed. For example, Maldivian reefs exhibited a significantly higher abundance in all size classes of 'competitive' corals compared to East Africa. This possibly indicates that East African reefs have already been subjected to higher levels of stress and are therefore less suitable environments for 'competitive' corals. This study also highlights the potential structure and composition of reefs under future degradation scenarios, for example with a loss of Acropora corals and an increase in dominance of 'stress tolerant' and 'generalist' coral genera. Copyright © 2017. Published by Elsevier Ltd.

Size of nesting female Broad-snouted Caimans (Caiman latirostris Daudin 1802).

PubMed

Leiva, P M L; Simoncini, M S; Portelinha, T C G; Larriera, A; Piña, C I

2018-03-12

The southern distribution of the Broad-snouted Caiman (Caiman latirostris Daudin 1802) in Argentina occurs in Santa Fe Province, where its population has been under management by "Proyecto Yacaré" since 1990. From 1997 to 2016, we captured 77 nesting female Broad-snouted Caimans in Santa Fe Province. Our results suggest that previously defined size classes for Broad-snouted Caiman do not adequately describe the reproductively mature female segment of the population. Here we propose to change size ranges for general size classes for Broad-snouted Caiman. In addition, we have observed that reintroduced reproductive females by Proyecto Yacaré represent about 32% of captured females. These results indicate that reintroduced females by the management program are surviving and reproducing in the wild at least up to 20 years.

Support Vector Data Description Model to Map Specific Land Cover with Optimal Parameters Determined from a Window-Based Validation Set.

PubMed

Zhang, Jinshui; Yuan, Zhoumiqi; Shuai, Guanyuan; Pan, Yaozhong; Zhu, Xiufang

2017-04-26

This paper developed an approach, the window-based validation set for support vector data description (WVS-SVDD), to determine optimal parameters for support vector data description (SVDD) model to map specific land cover by integrating training and window-based validation sets. Compared to the conventional approach where the validation set included target and outlier pixels selected visually and randomly, the validation set derived from WVS-SVDD constructed a tightened hypersphere because of the compact constraint by the outlier pixels which were located neighboring to the target class in the spectral feature space. The overall accuracies for wheat and bare land achieved were as high as 89.25% and 83.65%, respectively. However, target class was underestimated because the validation set covers only a small fraction of the heterogeneous spectra of the target class. The different window sizes were then tested to acquire more wheat pixels for validation set. The results showed that classification accuracy increased with the increasing window size and the overall accuracies were higher than 88% at all window size scales. Moreover, WVS-SVDD showed much less sensitivity to the untrained classes than the multi-class support vector machine (SVM) method. Therefore, the developed method showed its merits using the optimal parameters, tradeoff coefficient ( C ) and kernel width ( s ), in mapping homogeneous specific land cover.

A complementary graphical method for reducing and analyzing large data sets. Case studies demonstrating thresholds setting and selection.

PubMed

Jing, X; Cimino, J J

2014-01-01

Graphical displays can make data more understandable; however, large graphs can challenge human comprehension. We have previously described a filtering method to provide high-level summary views of large data sets. In this paper we demonstrate our method for setting and selecting thresholds to limit graph size while retaining important information by applying it to large single and paired data sets, taken from patient and bibliographic databases. Four case studies are used to illustrate our method. The data are either patient discharge diagnoses (coded using the International Classification of Diseases, Clinical Modifications [ICD9-CM]) or Medline citations (coded using the Medical Subject Headings [MeSH]). We use combinations of different thresholds to obtain filtered graphs for detailed analysis. The thresholds setting and selection, such as thresholds for node counts, class counts, ratio values, p values (for diff data sets), and percentiles of selected class count thresholds, are demonstrated with details in case studies. The main steps include: data preparation, data manipulation, computation, and threshold selection and visualization. We also describe the data models for different types of thresholds and the considerations for thresholds selection. The filtered graphs are 1%-3% of the size of the original graphs. For our case studies, the graphs provide 1) the most heavily used ICD9-CM codes, 2) the codes with most patients in a research hospital in 2011, 3) a profile of publications on "heavily represented topics" in MEDLINE in 2011, and 4) validated knowledge about adverse effects of the medication of rosiglitazone and new interesting areas in the ICD9-CM hierarchy associated with patients taking the medication of pioglitazone. Our filtering method reduces large graphs to a manageable size by removing relatively unimportant nodes. The graphical method provides summary views based on computation of usage frequency and semantic context of hierarchical terminology. The method is applicable to large data sets (such as a hundred thousand records or more) and can be used to generate new hypotheses from data sets coded with hierarchical terminologies.

Biochemical distributions (amino acids, neutral sugars, and lignin phenols) among size-classes of modern marine sediments from the Washington coast

NASA Astrophysics Data System (ADS)

Keil, Richard G.; Tsamakis, Elizabeth; Giddings, J. Calvin; Hedges, John I.

1998-04-01

In order to examine relationships of organic matter source, composition, and diagenesis with particle size and mineralogy in modern marine depositional regimes, sediments from the continental shelf and slope along the Northwest Pacific rim (Washington coast, USA) were sorted into hydrodynamic size fractions (sand: >250, 63-250 μm; silt: 35-63, 17-35, 8-17, 3-8 μm; and clay-sized: 1-3, 0.5-1, <0.5 μm). The size fractions were then density fractionated to separate distinct organic debris from mineral-associated organic matter, and the various separates were analyzed for their amino acid, aldose, and lignin compositions. The composition of organic matter in the separates changes markedly as a function of particle size and density. Large compositional differences were observed between the clay-sized fractions (dominated mineralogically by smectites), the sand-sized mineral-associated isolates (quartz-rich), and floated coarse organic matter (dominated by vascular plant debris). Organic matter intimately associated with the clay-sized fractions shows the most extensive diagenetic alteration, as reflected in high abundances of nonprotein amino acids (especially β-alanine), elevated lignin phenol acid/aldehyde ratios, and high relative concentrations of the deoxyhexoses fucose and rhamnose. Organic matter in the silt fractions, though degraded, is not as diagenetically altered as in the clay fractions. Enrichment of pollen grains in the silt-size material is reflected by high cinnamic acid to ferulic acid lignin phenol ratios. The highest pollen biochemical signal is observed in the silt fractions of the deepest station (1835 m), where pollen abundances are also highest. Organic matter tightly bound in the silt and sand-sized fractions are enriched in aldoses and show indications of enhanced microbial biomass as reflected by high weight percentages of ribose. Distinct organic debris was composed of relatively unaltered vascular plant remains as reflected by high lignin phenol yields and low acid/aldehyde ratios. Clay-size fractions are enriched in nitrogenous components, as reflected by elevated yields of total and basic amino acids (especially lysine). Silt- and sand-size fractions rich in quartz and albite show slightly higher yields of neutral amino acids. Consistent trends across all size classes and among the different depositional settings illustrates that only a small portion of the organic matter is present as distinct organic debris (e.g. pollen, vascular plant tissues, etc.), but that this debris can be isolated in specific size classes. The data for surface-associated organic matter are consistent with, but not conclusive of, selective partitioning of some organic matter to specific mineral surfaces. The dominant size class-specific trends in organic matter composition are due to changes in both source and diagenetic alteration.

The effects of overwinter flowson the spring condition of rainbow and brown trout size classes in the Green River downstream of Flaming Gorge Dam, Utah.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Magnusson, A. K.; LaGory, K. E.; Hayse, J. W.

2010-06-25

Flaming Gorge Dam, a hydroelectric facility operated by the Bureau of Reclamation (Reclamation), is located on the Green River in Daggett County, northeastern Utah. Until recently, and since the early 1990s, single daily peak releases or steady flows have been the operational pattern of the dam during the winter period. However, releases from Flaming Gorge Reservoir followed a double-peak pattern (two daily flow peaks) during the winters of 2006-2007 and 2008-2009. Because there is little recent long-term history of double-peaking at Flaming Gorge Dam, the potential effects of double-peaking operations on trout body condition in the dam's tailwater are notmore » known. A study plan was developed that identified research activities to evaluate potential effects from winter double-peaking operations (Hayse et al. 2009). Along with other tasks, the study plan identified the need to conduct a statistical analysis of historical trout condition and macroinvertebrate abundance to evaluate the potential effects of hydropower operations. The results from analyses based on the combined size classes of trout (85-630 mm) were presented in Magnusson et al. (2008). The results of this earlier analysis suggested possible relationships between trout condition and flow, but concern that some of the relationships resulted from size-based effects (e.g., apparent changes in condition may have been related to concomitant changes in size distribution, because small trout may have responded differently to flow than large trout) prompted additional analysis of within-size class relationships. This report presents the results of analyses of three different size classes of trout (small: 200-299 mm, medium: 300-399 mm, and large: {ge}400 mm body length). We analyzed historical data to (1) describe temporal patterns and relationships among flows, benthic macroinvertebrate abundance, and condition of brown trout (Salmo trutta) and rainbow trout (Oncorhynchus mykiss) in the tailwaters of Flaming Gorge Dam, and to (2) evaluate the relative importance of the effects of flow (i.e., flow volumes and flow variability), trout abundance (catch per unit effort [CPUE]), and benthic macroinvertebrate abundance on trout condition for different size classes of trout.« less

Microstructural indicators of convection: insights from the Little Minch Sill Complex, Scotland

NASA Astrophysics Data System (ADS)

Nicoli, Gautier; Holness, Marian; Neufeld, Jerome; Farr, Robert

2017-04-01

The fluid dynamic behaviour of crystal-bearing magmas is a key parameter to understand the formation of magmatic bodies. There are two opposite views on the subject: Some argue that solidification in intrusive bodies is affected by convection whereas others claim solidification happens in a static environment. A consensus on the question may be reached by carefully studying the grain size distribution in the settled accumulations of cargo crystals. In the absence of significant crystal growth or particle coarsening by agglomeration, settling of a polydisperse crystal load will always result in a fining-upwards sequence in static magmas as well as in convecting environments. If we assume the particle concentration is always sufficiently low to prevent hindered settling, gravitational settling in a static magma leads to the settling of individual crystals at a constant rate determined by their Stokes' velocity. Each size class is deposited at a constant rate, until all the grains of that size class have fallen out of suspension, leading to a well-stratified sequence and the complete disappearance of progressively smaller size classes upwards in the accumulation. In contrast, in a vigorously convecting magma crystals settle when they enter the stagnant basal boundary layer. In a system containing a polydisperse crystal population most of the bigger particles are removed rapidly from the bulk magma, leading to the creation of a fining-upwards sequence on the floor. However, in detail the structure of this fining-upwards sequence is critically different from that created by settling from a stagnant magma, with the gradual phasing out of each size class instead of the abrupt termination of size classes seen in static systems. This provides us with the opportunity to distinguish between settling from static or convecting magma using the spatial variation of grain size in settled accumulations. We focus on the Little Minch Sill Complex in Scotland, which formed from olivine-phyric magma and is characterised by both composite and single-injection bodies with significant accumulation of olivine on their lower margins. Comparison of the fining-upwards sequences in the picrodolerite/crinanite unit of the composite Shiant Isles Main Sill,and related single-injection sills on the Trotternish Peninsula, Skye, illustrate the ability of this method to distinguish between convecting and non-convecting magma bodies.

The size-reactivity continuum of major bioelements in the ocean.

PubMed

Benner, Ronald; Amon, Rainer M W

2015-01-01

Most of the carbon fixed in primary production is rapidly cycled and remineralized, leaving behind various forms of organic carbon that contribute to a vast reservoir of nonliving organic matter in seawater. Most of this carbon resides in dissolved molecules of varying bioavailability and reactivity, and aspects of the cycling of this carbon remain an enigma. The size-reactivity continuum model provides a conceptual framework for understanding the mechanisms governing the formation and mineralization of this carbon. In the seawater bioassay experiments that served as the original basis for this model, investigators observed that larger size classes of organic matter were more bioavailable and more rapidly remineralized by microbes than were smaller size classes. Studies of the chemical composition and radiocarbon content of marine organic matter have further indicated that the complexity and age of organic matter increase with decreasing molecular size. Biodegradation processes appear to shape the size distribution of organic matter and the nature of the small dissolved molecules that persist in the ocean.

Analysis of spatial distribution of land cover maps accuracy

NASA Astrophysics Data System (ADS)

Khatami, R.; Mountrakis, G.; Stehman, S. V.

2017-12-01

Land cover maps have become one of the most important products of remote sensing science. However, classification errors will exist in any classified map and affect the reliability of subsequent map usage. Moreover, classification accuracy often varies over different regions of a classified map. These variations of accuracy will affect the reliability of subsequent analyses of different regions based on the classified maps. The traditional approach of map accuracy assessment based on an error matrix does not capture the spatial variation in classification accuracy. Here, per-pixel accuracy prediction methods are proposed based on interpolating accuracy values from a test sample to produce wall-to-wall accuracy maps. Different accuracy prediction methods were developed based on four factors: predictive domain (spatial versus spectral), interpolation function (constant, linear, Gaussian, and logistic), incorporation of class information (interpolating each class separately versus grouping them together), and sample size. Incorporation of spectral domain as explanatory feature spaces of classification accuracy interpolation was done for the first time in this research. Performance of the prediction methods was evaluated using 26 test blocks, with 10 km × 10 km dimensions, dispersed throughout the United States. The performance of the predictions was evaluated using the area under the curve (AUC) of the receiver operating characteristic. Relative to existing accuracy prediction methods, our proposed methods resulted in improvements of AUC of 0.15 or greater. Evaluation of the four factors comprising the accuracy prediction methods demonstrated that: i) interpolations should be done separately for each class instead of grouping all classes together; ii) if an all-classes approach is used, the spectral domain will result in substantially greater AUC than the spatial domain; iii) for the smaller sample size and per-class predictions, the spectral and spatial domain yielded similar AUC; iv) for the larger sample size (i.e., very dense spatial sample) and per-class predictions, the spatial domain yielded larger AUC; v) increasing the sample size improved accuracy predictions with a greater benefit accruing to the spatial domain; and vi) the function used for interpolation had the smallest effect on AUC.

Tooth size discrepancies in Class II division 1 and Class III malocclusion requiring surgical-orthodontic or orthodontic treatment.

PubMed

McSwiney, Timothy P; Millett, Declan T; McIntyre, Grant T; Barry, Mark K; Cronin, Michael S

2014-06-01

To compare mean anterior (AR) and mean overall (OR) tooth size ratios, prevalence of clinically significant tooth size discrepancies (TSDs) and correlation between AR and OR in subjects with Class II division 1 and Class III malocclusion treated by surgical-orthodontic or orthodontic means. Retrospective, cross-sectional. State-funded and private clinics. From pre-treatment cohorts of 770 surgical and 610 non-surgical subjects, Class II division 1 and Class III malocclusion groups were identified with 60 surgical and 60 non-surgical subjects, comprising 30 males and 30 females, in each. AR and OR were calculated by landmarking digital models. Differences in AR and OR and their relationship were analysed using two-way analysis of variance (ANOVA) and a correlation coefficient, respectively. The proportions of the surgical and non-surgical groups with a TSD were assessed using logistic regression. Intra-examiner reproducibility involved re-landmarking 30 randomly selected image sets and differences in ARs and ORs were compared using a paired t-test. Random error was assessed using the intraclass correlation coefficient (ICC). Analyses were performed using SAS (SAS Institute Inc., Cary, NC, USA) at the 5% level of significance. There were no statistically significant differences associated with the measurement of either the mean AR (P = 0·913) or the mean OR (P = 0·874). ICC values were very high (AR = 0·95; OR = 0·90). Differences existed between both Class II and Class III surgical (AR: P<0·001; OR: P<0·001) and non-surgical groups (AR: P = 0·012; OR: P = 0·003). The AR and OR relationship was strong (correlation coefficient = 0·72). The highest percentage of clinically significant TSDs was seen in the AR of both Class II and Class III surgical groups (23·3%). In the cohort examined: AR and OR differed significantly for malocclusion groups. The prevalence of clinically significant TSDs did not differ significantly between surgical and non-surgical groups although the highest percentage of clinically significant TSDs was recorded for AR in Class II and Class III surgical cases. AR and OR were closely related. © 2014 British Orthodontic Society.

Determining the Population Size of Pond Phytoplankton.

ERIC Educational Resources Information Center

Hummer, Paul J.

1980-01-01

Discusses methods for determining the population size of pond phytoplankton, including water sampling techniques, laboratory analysis of samples, and additional studies worthy of investigation in class or as individual projects. (CS)

Large-scale changes in bloater growth and condition in Lake Huron

USGS Publications Warehouse

Prichard, Carson G.; Roseman, Edward F.; Keeler, Kevin M.; O'Brien, Timothy P.; Riley, Stephen C.

2016-01-01

Native Bloaters Coregonus hoyi have exhibited multiple strong year-classes since 2005 and now are the most abundant benthopelagic offshore prey fish in Lake Huron, following the crash of nonnative AlewivesAlosa pseudoharengus and substantial declines in nonnative Rainbow Smelt Osmerus mordax. Despite recent recoveries in Bloater abundance, marketable-size (>229 mm) Bloaters remain scarce. We used annual survey data to assess temporal and spatial dynamics of Bloater body condition and lengths at age in the main basin of Lake Huron from 1973 to 2014. Basinwide lengths at age were modeled by cohort for the 1973–2003 year-classes using a von Bertalanffy growth model with time-varying Brody growth coefficient (k) and asymptotic length () parameters. Median Bloater weights at selected lengths were estimated to assess changes in condition by modeling weight–length relations with an allometric growth model that allowed growth parameters to vary spatially and temporally. Estimated Bloater lengths at age declined 14–24% among ages 4–8 for all year-classes between 1973 and 2004. Estimates of  declined from a peak of 394 mm (1973 year-class) to a minimum of 238 mm (1998 year-class). Observed mean lengths at age in 2014 were at all-time lows, suggesting that year-classes comprising the current Bloater population would have to follow growth trajectories unlike those characterizing the 1973–2003 year-classes to attain marketable size. Furthermore, estimated weights of 250-mm Bloaters (i.e., a large, commercially valuable size-class) declined 17% among all regions from 1976 to 2007. Decreases in body condition of large Bloaters are associated with lower lipid content and may be linked to marked declines in abundance of the amphipodsDiporeia spp. in Lake Huron. We hypothesize that since at least 1976, large Bloaters have become more negatively buoyant and may have incurred an increasingly greater metabolic cost performing diel vertical migrations to prey upon the opossum shrimp Mysis diluviana and zooplankton.

A National Study Assessing the Teaching and Learning of Introductory Astronomy; Part I: The Effect of Interactive Instruction

NASA Astrophysics Data System (ADS)

Rudolph, Alexander; Prather, E. E.; Brissenden, G.; Schlingman, W. M.; CATS

2009-01-01

We present the results of a national study on the teaching and learning of astronomy taught in general education, non-science major, introductory astronomy courses (Astro 101). Nearly 4000 students enrolled in 69 sections of Astro 101 taught at 30 institutions around the United States completed (pre- and post-instruction) the Light and Spectroscopy Concept Inventory (LSCI) from Fall 2006 to Fall 2007. The classes varied in size from very small (N<10) to large (N 180) and were from all types of institutions, including both 2-year and 4-year colleges and universities. To study how the instruction in different classrooms affected student learning, we developed and administered an Interactivity Assessment Instrument (IAI). This short survey, completed by instructors, allowed us to estimate the fraction of total classroom time that was dedicated to the use of interactive learning strategies. Pre-instruction LSCI scores were clustered around 25% (24±2%), independent of class size and institution type; however, the normalized gains for these classes varied from about (-)0.07-0.50. These two results suggest that the differences in gain were due to instruction in the classroom, not the size of class or type of institution. Interactivity Assessment Scores (IAS's) ranged from 0%-50%, showing that our IAI was able to distinguish between classes with higher and lower levels of interactive instruction. A comparison of class-averaged gain score to IAS showed that higher interactivity classes (IAS > 25%) were the only instructional environments capable of reaching the highest gains ( > 0.30). However, the range of gains seen for the higher interactivity classes was quite wide, suggesting that the use of interactive learning strategies is not sufficient by itself to achieve high student gains. We acknowledge the NSF for funding under Award No. 0715517, a CCLI Phase III Grant for the Collaboration of Astronomy Teaching Scholars (CATS) Program.

Teething Problems in the Academy: Negotiating the Transition to Large-Class Teaching in the Discipline of History

ERIC Educational Resources Information Center

Keirle, Philip A.; Morgan, Ruth A.

2011-01-01

In this paper we provide a template for transitioning from tutorial to larger-class teaching environments in the discipline of history. We commence by recognising a number of recent trends in tertiary education in Australian universities that have made this transition to larger class sizes an imperative for many academics: increased student…

Integrated controls-structures design methodology development for a class of flexible spacecraft

NASA Technical Reports Server (NTRS)

Maghami, P. G.; Joshi, S. M.; Walz, J. E.; Armstrong, E. S.

1990-01-01

Future utilization of space will require large space structures in low-Earth and geostationary orbits. Example missions include: Earth observation systems, personal communication systems, space science missions, space processing facilities, etc., requiring large antennas, platforms, and solar arrays. The dimensions of such structures will range from a few meters to possibly hundreds of meters. For reducing the cost of construction, launching, and operating (e.g., energy required for reboosting and control), it will be necessary to make the structure as light as possible. However, reducing structural mass tends to increase the flexibility which would make it more difficult to control with the specified precision in attitude and shape. Therefore, there is a need to develop a methodology for designing space structures which are optimal with respect to both structural design and control design. In the current spacecraft design practice, it is customary to first perform the structural design and then the controller design. However, the structural design and the control design problems are substantially coupled and must be considered concurrently in order to obtain a truly optimal spacecraft design. For example, let C denote the set of the 'control' design variables (e.g., controller gains), and L the set of the 'structural' design variables (e.g., member sizes). If a structural member thickness is changed, the dynamics would change which would then change the control law and the actuator mass. That would, in turn, change the structural model. Thus, the sets C and L depend on each other. Future space structures can be roughly divided into four mission classes. Class 1 missions include flexible spacecraft with no articulated appendages which require fine attitude pointing and vibration suppression (e.g., large space antennas). Class 2 missions consist of flexible spacecraft with articulated multiple payloads, where the requirement is to fine-point the spacecraft and each individual payload while suppressing the elastic motion. Class 3 missions include rapid slewing of spacecraft without appendages, while Class 4 missions include general nonlinear motion of a flexible spacecraft with articulated appendages and robot arms. Class 1 and 2 missions represent linear mathematical modeling and control system design problems (except for actuator and sensor nonlinearities), while Class 3 and 4 missions represent nonlinear problems. The development of an integrated controls/structures design approach for Class 1 missions is addressed. The performance for these missions is usually specified in terms of (1) root mean square (RMS) pointing errors at different locations on the structure, and (2) the rate of decay of the transient response. Both of these performance measures include the contributions of rigid as well as elastic motion.

Mechanical properties of 3D printed warped membranes

NASA Astrophysics Data System (ADS)

Kosmrlj, Andrej; Xiao, Kechao; Weaver, James C.; Vlassak, Joost J.; Nelson, David R.

2015-03-01

We explore how a frozen background metric affects the mechanical properties of solid planar membranes. Our focus is a special class of ``warped membranes'' with a preferred random height profile characterized by random Gaussian variables h (q) in Fourier space with zero mean and variance < | h (q) | 2 > q-m . It has been shown theoretically that in the linear response regime, this quenched random disorder increases the effective bending rigidity, while the Young's and shear moduli are reduced. Compared to flat plates of the same thickness t, the bending rigidity of warped membranes is increased by a factor hv / t while the in-plane elastic moduli are reduced by t /hv , where hv =√{< | h (x) | 2 > } describes the frozen height fluctuations. Interestingly, hv is system size dependent for warped membranes characterized with m > 2 . We present experimental tests of these predictions, using warped membranes prepared via high resolution 3D printing.

On the degrees of freedom of reduced-rank estimators in multivariate regression

PubMed Central

Mukherjee, A.; Chen, K.; Wang, N.; Zhu, J.

2015-01-01

Summary We study the effective degrees of freedom of a general class of reduced-rank estimators for multivariate regression in the framework of Stein's unbiased risk estimation. A finite-sample exact unbiased estimator is derived that admits a closed-form expression in terms of the thresholded singular values of the least-squares solution and hence is readily computable. The results continue to hold in the high-dimensional setting where both the predictor and the response dimensions may be larger than the sample size. The derived analytical form facilitates the investigation of theoretical properties and provides new insights into the empirical behaviour of the degrees of freedom. In particular, we examine the differences and connections between the proposed estimator and a commonly-used naive estimator. The use of the proposed estimator leads to efficient and accurate prediction risk estimation and model selection, as demonstrated by simulation studies and a data example. PMID:26702155

At-home laser treatment of oral neuronal disorders: Case reports

PubMed Central

Rocca, Jean-Paul; Oppici, Aldo; Cella, Luigi; Fornaini, Carlo

2017-01-01

The neuronal disorders occurring in the oral district are mainly anaesthesia, paraesthesia, hypoesthesia and hyperaesthesia and they may occur frequently after surgical procedures. Medical treatment depends on degree of severity of the nerve injury but, in every case, it must be immediately carried out to reduce immune inflammatory reaction. The aim of this report is to investigate the effectiveness in the recovery of the peripheral nerve lesions of a new laser device recently proposed by the commerce that, due to its reduced size and to be a class I laser according the ANSI classification, may be used at home by the patient himself. Three different cases were treated with this “at-home approach”: complete resolution of symptomatology was obtained after laser treatment with a good compliance for the patient and without reporting any side effect. Key words:Laser, biomodulation, low level laser therapy, oral neuronal disorders, at-home treatment, paresthesia. PMID:28469830

Financial implications of increasing medical school class size: does tuition cover cost?

PubMed

Schieffler, Danny A; Azevedo, Benjamin M; Culbertson, Richard A; Kahn, Marc J

2012-01-01

In 2006, the Association of American Medical Colleges (AAMC) issued a recommendation that medical schools increase the supply of physicians by 30% to meet the patient needs of the new millennium. To provide financial analysis of the cost of increasing class size. To determine the financial consequences of increasing medical student enrollment and in the absence of nationally published cost data for medical schools, adjusted secondary revenue data was analyzed using AAMC and Liaison Committee on Medical Education (LCME) financial data from 2009. Linear regression analysis was used to determine average fixed costs and variable cost per student in USD. In USD, $62,877 represents the best point estimate of the annual variable cost of educating a medical student. Comparing this cost to current tuitions and fees of LCME-accredited medical schools suggests that revenues other than tuition are needed to cover increases in class size. Tuition and fees revenue from increasing enrollment will not increase overall revenue to medical schools.

Effects of Soybean Seed Size on Weed Competition

USDA-ARS?s Scientific Manuscript database

Organic soybean producers must rely on various, nonherbicidal tactics for weed management. Increased soybean seed size may be one method to increase the competitiveness of the soybean canopy. Soybean varieties Hutcheson, NC-Roy, and NC-Raleigh were separated into four or five seed size classes. Seed...

Tradeoffs in basal area growth and reproduction shift over the lifetime of a long-lived tropical species.

PubMed

Staudhammer, Christina L; Wadt, Lúcia H O; Kainer, Karen A

2013-09-01

Understanding of the extent to which reproductive costs drive growth largely derives from reproductively mature temperate trees in masting and non-masting years. We modeled basal area increment (BAI) and explored current growth-reproduction tradeoffs and changes in such allocation over the life span of a long-lived, non-masting tropical tree. We integrated rainfall and soil variables with data from 190 Bertholletia excelsa trees of different diameter at breast height (DBH) sizes, crown characteristics, and liana loads, quantifying BAI and reproductive output over 4 and 6 years, respectively. While rainfall explains BAI in all models, regardless of DBH class or ontogenic stage, light (based on canopy position and crown form) is most critical in the juvenile (5 cm ≤ DBH < 50 cm) phase. Suppressed trees are only present as juveniles and grow ten times slower (1.45 ± 2.73 m(2) year(-1)) than trees in dominant and co-dominant positions (13.25 ± 0.82 and 12.90 ± 1.35 m(2) year(-1), respectively). Additionally, few juvenile trees are reproductive, and those that are, demonstrate reduced growth, as do reproductive trees in the next 50 to 100 cm DBH class, suggesting growth-reproduction tradeoffs. Upon reaching the canopy, however, and attaining a sizeable girth, this pattern gradually shifts to one where BAI and reproduction are influenced independently by variables such as liana load, crown size and soil properties. At this stage, BAI is largely unaffected by fruit production levels. Thus, while growth-reproduction tradeoffs clearly exist during early life stages, effects of reproductive allocation diminish as B. excelsa increases in size and maturity.

Breakup and reestablishment of the armour layer in a large gravel-bed river below dams: The lower Ebro

NASA Astrophysics Data System (ADS)

Vericat, Damia; Batalla, Ramon J.; Garcia, Celso

2006-06-01

Changes in armour layer during floods under supply limited conditions are little known. This paper describes the breakup and the reestablishment of the bed armour layer in the regulated gravel-bed Ebro River during a flooding period. The study was conducted over a 28-km study reach from 2002 to 2004. The surface, subsurface and bed load grain size distribution constitute the bases for the analysis of bed-armouring dynamics. The results indicate that the magnitude of floods controlled the degree of armouring of the river bed. The initial mean armouring ratio was 2.3, with maximum values reaching 4.4. Floods in the winter of 2002-2003 ( Q8) caused the breakup of the armour layer in several sections. This resulted in the erratic bed load pattern observed during the December 2002 flushing flow and in the increase in bed load transport during successive events. Most grain size classes were entrained and transported, causing river bed incision. The mean armouring ratio decreased to 1.9. In contrast, during low magnitude floods in 2003-2004 ( Q2), the coarsest fractions (64 mm) did not take part in the bed load while finer particles were winnowed, thus surface deposits coarsened. As a result, the armour layer was reestablished (i.e., the mean armouring ratio increased to 2.3), and the supply of subsurface sediment decreased. The supply and transport of bed material appear to be in balance in the river reach immediately below the dam. In contrast, the transport of medium and finer size classes in the downstream reaches was higher than their supply from upstream, a phenomenon that progressively reduced their availability in the river bed surface, hence the armour layer reworking.

Observed effects of an exceptional drought on tree mortality in a tropical dry forest

NASA Astrophysics Data System (ADS)

Medvigy, D.; Vargas, G.; Xu, X.; Smith, C. M.; Becknell, J.; Brodribb, T.; Powers, J. S.

2016-12-01

Climate models predict that the coming century will bring reduced rainfall to Neotropical dry forests. It is unknown how tropical dry forest trees will respond to such rainfall reductions. Will there be increased mortality? If so, what will be the dominant mechanism of mortality? Will certain functional groups or size classes be more susceptible to unusually dry conditions and do functional traits underlie these patterns? With these questions in mind, we analyzed the response of trees from 18 Costa Rican tropical dry forest inventory plots and from additional transects to the exceptional 2015 drought that coincided with a strong ENSO event. We compared stand-level mortality rates observed during pre-drought years (2008-2014) and during the drought year of 2015 in the inventory plots. For both inventory plots and transects, we analyzed whether particular functional groups or size classes experienced exceptional mortality after the drought. We found that mortality rates were two to three times higher during the drought than before the drought. In contrast to observations at moist tropical forests, tree size had little influence on mortality. In terms of functional groups, mortality rates of evergreen oaks growing on nutrient-poor soils particularly increased during drought. Legumes seemed less affected by the drought than non-legumes. However, elevated mortality rates were not clearly correlated with commonly-measured traits like wood density or specific leaf area. Instead, hydraulic traits like P50 or turgor loss point may be better predictors of drought-driven mortality. In addition, trees that died during the drought tended to have smaller relative growth rate prior to the drought than trees that survived the drought.

Evaluation of AQUI-S(TM) (efficacy and minimum toxic concentration) as a fish anaesthetic/sedative for public aquaculture in the United States

USGS Publications Warehouse

Stehly, G.R.; Gingerich, W.H.

1999-01-01

A preliminary evaluation of efficacy and minimum toxic concentration of AQUI-S(TM), a fish anaesthetic/sedative, was determined in two size classes of six species of fish important to US public aquaculture (bluegill, channel catfish, lake trout, rainbow trout, walleye and yellow perch). In addition, efficacy and minimum toxic concentration were determined in juvenile-young adult (fish aged 1 year or older) rainbow trout acclimated to water at 7 ??C, 12 ??C and 17 ??C. Testing concentrations were based on determinations made with range-finding studies for both efficacy and minimum toxic concentration. Most of the tested juvenile-young adult fish species were induced in 3 min or less at a nominal AQUI-S(TM) concentration of 20 mg L-1. In juvenile-young adult fish, the minimum toxic concentration was at least 2.5 times the selected efficacious concentration. Three out of five species of fry-fingerlings (1.25-12.5 cm in length and < 1 year old) were induced in ??? 4.1 min at a nominal concentration of 20 mg L-1 AQUI-S(TM), with the other two species requiring nominal concentrations of 25 and 35 mg L-1 for similar times of induction. Recovery times were ??? 7.3 rain for all species in the two size classes. In fry-fingerlings, the minimum toxic concentration was at least 1.4 times the selected efficacious concentration. There appeared to be little relationship between size of fish and concentrations or times to induction, recovery times and minimum toxic concentration. The times required for induction and for recovery were increased in rainbow trout as the acclimation temperature was reduced.

Lysis Delay and Burst Shrinkage of Coliphage T7 by Deletion of Terminator Tφ Reversed by Deletion of Early Genes

PubMed Central

Nguyen, Huong Minh

2014-01-01

ABSTRACT Bacteriophage T7 terminator Tφ is a class I intrinsic terminator coding for an RNA hairpin structure immediately followed by oligo(U), which has been extensively studied in terms of its transcription termination mechanism, but little is known about its physiological or regulatory functions. In this study, using a T7 mutant phage, where a 31-bp segment of Tφ was deleted from the genome, we discovered that deletion of Tφ from T7 reduces the phage burst size but delays lysis timing, both of which are disadvantageous for the phage. The burst downsizing could directly result from Tφ deletion-caused upregulation of gene 17.5, coding for holin, among other Tφ downstream genes, because infection of gp17.5-overproducing Escherichia coli by wild-type T7 phage showed similar burst downsizing. However, the lysis delay was not associated with cellular levels of holin or lysozyme or with rates of phage adsorption. Instead, when allowed to evolve spontaneously in five independent adaptation experiments, the Tφ-lacking mutant phage, after 27 or 29 passages, recovered both burst size and lysis time reproducibly by deleting early genes 0.5, 0.6, and 0.7 of class I, among other mutations. Deletion of genes 0.5 to 0.7 from the Tφ-lacking mutant phage decreased expression of several Tφ downstream genes to levels similar to that of the wild-type phage. Accordingly, phage T7 lysis timing is associated with cellular levels of Tφ downstream gene products. This suggests the involvement of unknown factor(s) besides the known lysis proteins, lysozyme and holin, and that Tφ plays a role of optimizing burst size and lysis time during T7 infection. IMPORTANCE E. coli PMID:24335287

Effect of particle size distribution on 3D packings of spherical particles

NASA Astrophysics Data System (ADS)

Taiebat, Mahdi; Mutabaruka, Patrick; Pellenq, Roland; Radjai, Farhang

2017-06-01

We use molecular dynamics simulations of frictionless spherical particles to investigate a class of polydisperse granular materials in which the particle size distribution is uniform in particle volumes. The particles are assembled in a box by uniaxial compaction under the action of a constant stress. Due to the absence of friction and the nature of size distribution, the generated packings have the highest packing fraction at a given size span, defined as the ratio α of the largest size to the smallest size. We find that, up to α = 5, the packing fraction is a nearly linear function of α. While the coordination number is nearly constant due to the isostatic nature of the packings, we show that the connectivity of the particles evolves with α. In particular, the proportion of particles with 4 contacts represents the largest proportion of particles mostly of small size. We argue that this particular class of particles occurs as a result of the high stability of local configurations in which a small particle is stuck by four larger particles.

The limited contribution of large trees to annual biomass production in an old-growth tropical forest.

PubMed

Ligot, Gauthier; Gourlet-Fleury, Sylvie; Ouédraogo, Dakis-Yaoba; Morin, Xavier; Bauwens, Sébastien; Baya, Fidele; Brostaux, Yves; Doucet, Jean-Louis; Fayolle, Adeline

2018-04-16

Although the importance of large trees regarding biodiversity and carbon stock in old-growth forests is undeniable, their annual contribution to biomass production and carbon uptake remains poorly studied at the stand level. To clarify the role of large trees in biomass production, we used data of tree growth, mortality, and recruitment monitored during 20 yr in 10 4-ha plots in a species-rich tropical forest (Central African Republic). Using a random block design, three different silvicultural treatments, control, logged, and logged + thinned, were applied in the 10 plots. Annual biomass gains and losses were analyzed in relation to the relative biomass abundance of large trees and by tree size classes using a spatial bootstrap procedure. Although large trees had high individual growth rates and constituted a substantial amount of biomass, stand-level biomass production decreased with the abundance of large trees in all treatments and plots. The contribution of large trees to annual stand-level biomass production appeared limited in comparison to that of small trees. This pattern did not only originate from differences in abundance of small vs. large trees or differences in initial biomass stocks among tree size classes, but also from a reduced relative growth rate of large trees and a relatively constant mortality rate among tree size classes. In a context in which large trees are increasingly gaining attention as being a valuable and a key structural characteristic of natural forests, the present study brought key insights to better gauge the relatively limited role of large trees in annual stand-level biomass production. In terms of carbon uptake, these results suggest, as already demonstrated, a low net carbon uptake of old-growth forests in comparison to that of logged forests. Tropical forests that reach a successional stage with relatively high density of large trees progressively cease to be carbon sinks as large trees contribute sparsely or even negatively to the carbon uptake at the stand level. © 2018 by the Ecological Society of America.

Size-resolved ultrafine particle composition analysis 1. Atlanta

NASA Astrophysics Data System (ADS)

Rhoads, K. P.; Phares, D. J.; Wexler, A. S.; Johnston, M. V.

2003-04-01

During August 1999 as part of the Southern Oxidants Study Supersite Experiment, our group collected size-resolved measurements of the chemical composition of single ambient aerosol particles with a unique real-time laser desorption/ionization mass spectrometry technique. The rapid single-particle mass spectrometry instrument is capable of analyzing "ultrafine" particles with aerodynamic diameters ranging from 0.01 to 1.5 μm. Under the heaviest loading observed in Atlanta, particles were analyzed at a rate of roughly one per second in sizes ranging from 0.1 to 0.2 μm. Nearly 16,000 individual spectra were recorded over the course of the month during both daytime and nighttime sampling periods. Evaluation of the data indicates that the composition of the ultrafine (less than 100 nm) particles is dominated by carbon-containing compounds. Larger particles show varied compositions but typically appeared to have organic carbon characteristics mixed with an inorganic component (e.g., crustal materials, metals, etc.). During the experiment, 70 composition classes were identified. In this paper we report the average spectra and correlations with various meteorological parameters for all major compound classes and a number of minor ones. The major composition classes are identified from the primary peaks in their spectra as organic carbon (about 74% of the particles), potassium (8%), iron (3%), calcium (2%), nitrate (2%), elemental carbon (1.5%), and sodium (1%). Many of these compound classes appeared in repeatable size ranges and quadrants of the wind rose, indicating emission from specific sources.

Carbon Storage in Soil Size Fractions Under Two Cacao Agroforestry Systems in Bahia, Brazil

NASA Astrophysics Data System (ADS)

Gama-Rodrigues, Emanuela F.; Ramachandran Nair, P. K.; Nair, Vimala D.; Gama-Rodrigues, Antonio C.; Baligar, Virupax C.; Machado, Regina C. R.

2010-02-01

Shaded perennial agroforestry systems contain relatively high quantities of soil carbon (C) resulting from continuous deposition of plant residues; however, the extent to which the C is sequestered in soil will depend on the extent of physical protection of soil organic C (SOC). The main objective of this study was to characterize SOC storage in relation to soil fraction-size classes in cacao ( Theobroma cacao L.) agroforestry systems (AFSs). Two shaded cacao systems and an adjacent natural forest in reddish-yellow Oxisols in Bahia, Brazil were selected. Soil samples were collected from four depth classes to 1 m depth and separated by wet-sieving into three fraction-size classes (>250 μm, 250-53 μm, and <53 μm)—corresponding to macroaggregate, microaggregate, and silt-and-clay size fractions—and analyzed for C content. The total SOC stock did not vary among systems (mean: 302 Mg/ha). On average, 72% of SOC was in macroaggregate-size, 20% in microaggregate-size, and 8% in silt-and-clay size fractions in soil. Sonication of aggregates showed that occlusion of C in soil aggregates could be a major mechanism of C protection in these soils. Considering the low level of soil disturbances in cacao AFSs, the C contained in the macroaggregate fraction might become stabilized in the soil. The study shows the role of cacao AFSs in mitigating greenhouse gas (GHG) emission through accumulation and retention of high amounts of organic C in the soils and suggests the potential benefit of this environmental service to the nearly 6 million cacao farmers worldwide.

Carbon storage in soil size fractions under two cacao agroforestry systems in Bahia, Brazil.

PubMed

Gama-Rodrigues, Emanuela F; Ramachandran Nair, P K; Nair, Vimala D; Gama-Rodrigues, Antonio C; Baligar, Virupax C; Machado, Regina C R

2010-02-01

Shaded perennial agroforestry systems contain relatively high quantities of soil carbon (C) resulting from continuous deposition of plant residues; however, the extent to which the C is sequestered in soil will depend on the extent of physical protection of soil organic C (SOC). The main objective of this study was to characterize SOC storage in relation to soil fraction-size classes in cacao (Theobroma cacao L.) agroforestry systems (AFSs). Two shaded cacao systems and an adjacent natural forest in reddish-yellow Oxisols in Bahia, Brazil were selected. Soil samples were collected from four depth classes to 1 m depth and separated by wet-sieving into three fraction-size classes (>250 microm, 250-53 microm, and <53 microm)-corresponding to macroaggregate, microaggregate, and silt-and-clay size fractions-and analyzed for C content. The total SOC stock did not vary among systems (mean: 302 Mg/ha). On average, 72% of SOC was in macroaggregate-size, 20% in microaggregate-size, and 8% in silt-and-clay size fractions in soil. Sonication of aggregates showed that occlusion of C in soil aggregates could be a major mechanism of C protection in these soils. Considering the low level of soil disturbances in cacao AFSs, the C contained in the macroaggregate fraction might become stabilized in the soil. The study shows the role of cacao AFSs in mitigating greenhouse gas (GHG) emission through accumulation and retention of high amounts of organic C in the soils and suggests the potential benefit of this environmental service to the nearly 6 million cacao farmers worldwide.

Characterization of suspended particles in Everglades wetlands

USGS Publications Warehouse

Noe, G.B.; Harvey, J.W.; Saiers, J.E.

2007-01-01

We report the concentration, phosphorus (P) and nitrogen (N) content, and size and chemical fractionation of fine suspended particles (0.2-100 ??m) and colloids (3 kilodalton [kDa]-0.1 ??m) in the surface water of Everglades wetlands along regional and P-enrichment gradients. Total suspended sediment concentrations ranged from 0.7 to 2.7 mg L-1. Total particulate P concentrations increased from 0.05 ??mol L-1 to 0.31 ??mol L -1 along the P-enrichment gradient. Particles contained from 20% to 43% of total P but <12% of total N in surface water. Dissolved (<0.2 ??m) organic N contained about 90% of total N, with the 3-100-kDa colloidal size class containing the most N of any size class. The 0.45-2.7-??m size fraction held the most particulate P at all sites, whereas particulate N was most abundant in the 2.7-10-??m size class at most sites. Standard chemical fractionation of particles identified acid-hydrolyzable P as the most abundant species of particulate P, with little reactive or refractory organic P. Sequential chemical extraction revealed that about 65% of total particulate P was microbial, while about 25% was associated with humic and fulvic organic matter. The size and chemical fractionation information suggested that P-rich particles mostly consisted of suspended bacteria. Suspended particles in Everglades wetlands were small in size and had low concentrations, yet they stored a large proportion of surface-water P in intermediately reactive forms, but they held little N. ?? 2007, by the American Society of Limnology and Oceanography, Inc.

Plankton copper requirements and uptake in the subarctic Northeast Pacific Ocean

NASA Astrophysics Data System (ADS)

Semeniuk, David M.; Cullen, Jay T.; Johnson, W. Keith; Gagnon, Katie; Ruth, Thomas J.; Maldonado, Maria T.

2009-07-01

We undertook the first measurements of metabolic Cu requirements (net Cu:C assimilation ratios) and steady-state Cu uptake rates (ρCu ss) of natural plankton assemblages in the northeast subarctic Pacific using the short-lived radioisotope 67Cu. Size-fractionated net Cu:C assimilation ratios varied ˜3 fold (1.35-4.21 μmol Cu mol C -1) among the stations along Line P, from high Fe coastal waters to the Fe-limited open ocean. The variability in Cu:C was comparable to biogenic Fe:C ratios in this region. As previously observed for Fe uptake, the bacterial size class accounted for half of the total particulate ρCu ss. Interestingly, carbon biomass-normalized rates of Fe uptake from the siderophore desferrioxamine B (DFB) (ρFe DFB; a physiological proxy for Fe-limitation) by the >20 μm size class were positively correlated with the intracellular net Cu:C assimilation ratios in this size class, suggesting that intracellular Cu requirements for large phytoplankton respond to increased Fe-limitation. At Fe-limited Ocean Station Papa (OSP), we performed short-term Cu uptake (ρCu L) assays to determine the relative bioavailability of Cu bound to natural and synthetic ligands. Like the volumetric ρCu ss measured along Line P, the bacterial size class was responsible for at least 50% of the total ρCu L. Uptake rates of Cu from the various organic complexes suggest that Cu uptake was controlled by the oxidation state of the metal and by the metal:ligand concentration ratio, rather than the concentration of inorganic species of Cu in solution. Collectively, these data suggest that Cu likely plays an important role in the physiology of natural plankton communities beyond the toxicological effects studied previously.

Analytical design equations for self-tuned Class-E power amplifier.

PubMed

Hu, Zhe; Troyk, Philip

2011-01-01

For many emerging neural prosthesis designs that are powered by inductive coupling, their small physical size requires large current in the extracorporeal transmitter coil, and the Class-E power amplifier topology is often used for the transmitter design. Tuning of Class-E circuits for efficient operation is difficult and a self-tuned circuit can facilitate the tuning. The coil current is sensed and used to tune the switching of the transistor switch in the Class-E circuit in order to maintain its high-efficiency operation. Although mathematically complex, the analysis and design procedure for the self-tuned Class-E circuit can be simplified due to the current feedback control, which makes the phase angle between the switching pulse and the coil current predetermined. In this paper explicit analytical design equations are derived and a detailed design procedure is presented and compared with the conventional Class-E design approaches.

Effectiveness of interceptive treatment of class III malocclusions with skeletal anchorage: A systematic review and meta-analysis.

PubMed

Rodríguez de Guzmán-Barrera, Jorge; Sáez Martínez, Carla; Boronat-Catalá, Montserrat; Montiel-Company, Jose María; Paredes-Gallardo, Vanessa; Gandía-Franco, José Luís; Almerich-Silla, José Manuel; Bellot-Arcís, Carlos

2017-01-01

Recently, new strategies for treating class III malocclusions have appeared. Skeletal anchorage appears to reduce the dentoalveolar effects while maximising the orthopaedic effect in growing patients. The purpose of this systematic review and meta-analysis is to examine the effectiveness of bone anchorage devices for interceptive treatment of skeletal class III malocclusions. Searches were made in the Pubmed, Embase, Scopus and Cochrane databases, as well as in a grey literature database, and were complemented by hand-searching. The criteria for eligibility were: patients who had undergone orthodontic treatment with skeletal anchorage (miniplates and miniscrews). Patients with syndromes or craniofacial deformities or who had undergone maxillofacial surgery were excluded. The following variables were recorded for each article: author, year of publication, type of study, sample size, dropouts, demographic variables, treatment carried out, radiographic study (2D or 3D), follow-up time, and quality of the articles on the Newcastle-Ottawa Scale. The means and confidence intervals of the following variables were employed: Wits, overjet, ANB, SNA and SNB. Initially, 239 articles were identified. After removing the duplicates and applying the selection criteria, 9 were included in the qualitative synthesis and 7 in the quantitative synthesis (meta-analysis). It may be concluded that skeletal anchorage is an effective treatment for improving skeletal Class III malocclusion, but when compared with other traditional treatments such as disjunction and face mask, there is no clear evidence that skeletal anchorage improves the results.

Effectiveness of interceptive treatment of class III malocclusions with skeletal anchorage: A systematic review and meta-analysis

PubMed Central

Rodríguez de Guzmán-Barrera, Jorge; Sáez Martínez, Carla; Boronat-Catalá, Montserrat; Montiel-Company, Jose María; Paredes-Gallardo, Vanessa; Gandía-Franco, José Luís; Almerich-Silla, José Manuel; Bellot-Arcís, Carlos

2017-01-01

Recently, new strategies for treating class III malocclusions have appeared. Skeletal anchorage appears to reduce the dentoalveolar effects while maximising the orthopaedic effect in growing patients. The purpose of this systematic review and meta-analysis is to examine the effectiveness of bone anchorage devices for interceptive treatment of skeletal class III malocclusions. Searches were made in the Pubmed, Embase, Scopus and Cochrane databases, as well as in a grey literature database, and were complemented by hand-searching. The criteria for eligibility were: patients who had undergone orthodontic treatment with skeletal anchorage (miniplates and miniscrews). Patients with syndromes or craniofacial deformities or who had undergone maxillofacial surgery were excluded. The following variables were recorded for each article: author, year of publication, type of study, sample size, dropouts, demographic variables, treatment carried out, radiographic study (2D or 3D), follow-up time, and quality of the articles on the Newcastle-Ottawa Scale. The means and confidence intervals of the following variables were employed: Wits, overjet, ANB, SNA and SNB. Initially, 239 articles were identified. After removing the duplicates and applying the selection criteria, 9 were included in the qualitative synthesis and 7 in the quantitative synthesis (meta-analysis). It may be concluded that skeletal anchorage is an effective treatment for improving skeletal Class III malocclusion, but when compared with other traditional treatments such as disjunction and face mask, there is no clear evidence that skeletal anchorage improves the results. PMID:28328995

What are the effects of anti-discriminatory legislation on socioeconomic inequalities in the employment consequences of ill health and disability?

PubMed

Bambra, Clare; Pope, Daniel

2007-05-01

To investigate how anti-discrimination legislation in the form of the UK Disability Discrimination Act (DDA) affected socioeconomic disparities in the employment rates of people with a limiting long-term illness (LLTI) or disability. National cross-sectional data on employment rates for people with and without an LLTI or disability were obtained from the General Household Survey (GHS) for a 14-year period (1990-2003; 12 surveys). Representative population samples were analysed. The sample size for the GHS over the study period ranged from 19,193 to 24,657 and the average response rate ranged from 72% to 82%. Age-standardised employment rates for individuals with and without an LLTI or disability, analysed by sex and socioeconomic status. Analysis of covariance identified that the DDA had had a negative effect on employment rates for individuals with an LLTI or disability during the study period. This negative effect was found to be differential according to social class ranging from no effect in social classes I and II (-2.86%, 95% CI -8.7% to 2.99%), increasing with social class group, to a highly significant effect in social classes IV and V (-10.7%, 95% CI -6.16% to -15.24%). No differential effect was identified by sex. Anti-discriminatory legislation is not an effective way of overcoming the employment consequences of ill health and disability, nor is it a useful public policy tool in terms of reducing inequalities.

Impact of titanium dioxide nanoparticles on the bacterial communities of biological activated carbon filter intended for drinking water treatment.

PubMed

Zhiyuan, Liu; Shuili, Yu; Heedeung, Park; Qingbin, Yuan; Guicai, Liu; Qi, Li

2016-08-01

Titanium dioxide nanoparticles (TiO2 NPs) are inevitably present in the aquatic environment owing to their increasing production and use. However, knowledge of the potential effects of TiO2 NPs on the treatment of drinking water is scarce. Herein, the effects of two types of anatase TiO2 NPs (TP1, 25 nm; TP2, 100 nm) on the bacterial community in a biological activated carbon (BAC) filter were investigated via quantitative polymerase chain reaction (Q-PCR) analysis, ATP quantification, and 454 pyrosequencing analysis. Both TP1 and TP2 significantly inhibited the bacterial ATP level (p < 0.01) and induced a decrease in the abundance of bacterial 16S rDNA gene copies at doses of 0.1 and 100 mg L(-1). Simultaneously, the diversity and evenness of the bacterial communities were considerably reduced. The relative abundances of bacteria annotated to OTUs from Nitrospira class and Betaproteobacteria class decreased upon TiO2 NP treatment, whereas those of Bacilli class and Gammaproteobacteria class increased. TiO2 NP size showed a greater effect on the bacterial composition than did the dose based on Bray-Curtis distances. These findings identified negative effects of TiO2 NPs on the bacterial community in the BAC filter. Given the fact that BAC filters are used widely in drinking water treatment plants, these results suggested a potential threat by TiO2 NP to drinking water treatment system.

Glycogen content in hepatocytes is related with their size in normal rat liver but not in cirrhotic one.

PubMed

Bezborodkina, Natalia N; Chestnova, Anna Yu; Vorobev, Mikhail L; Kudryavtsev, Boris N

2016-04-01

Hepatocytes differ from one another by the degree of the ploidy, size, position in the liver lobule, and level of the DNA-synthetic processes. It is believed, that the cell size exerts substantial influence on the metabolism of the hepatocytes and the glycogen content in them. The aim of the present study was to test this hypothesis. Dry weight of hepatocytes, their ploidy and glycogen content were determined in the normal and the cirrhotic rat liver. Liver cirrhosis in rats was produced by chronic inhalation of CCl4 vapours in the course of 6 months. A combined cytophotometric method was used. Dry weight of the cell, its glycogen and DNA content were successively measured on a mapped preparation. Hepatocytes of each ploidy class in the normal and the cirrhotic rat liver accumulated glycogen at the same rate. In the normal liver, there was a distinct correlation between the size of hepatocytes and glycogen content in them. This correlation was observed in each ploidy class, and was especially pronounced in the class of mononucleate tetraploid hepatocytes. In the cirrhotic liver, there was no correlation between the size of the cells and their glycogen content. The impairment of liver lobular structure probably explains the observed lack of correlation between hepatocyte size and their glycogen content in the cirrhotic liver. © 2016 International Society for Advancement of Cytometry. © 2016 International Society for Advancement of Cytometry.

Sublethal foot-predation on Donacidae (Mollusca: Bivalvia)

NASA Astrophysics Data System (ADS)

Salas, Carmen; Tirado, Cristina; Manjón-Cabeza, Maria Eugenia

2001-08-01

The incidence of foot nipping was studied on the Donax spp. of the littoral of Málaga (Southern Spain, 2875 specimens collected from February 1990 to January 1991) and of Ré island (French Atlantic coast, 262 specimens of Donax vittatus (Da Costa, 1778) collected in May 1996). In Málaga, Donax trunculus L., 1758 was the species most regularly nipped (18% of individuals), with peaks in summer (25% in August and 48% in September) and winter (34% in December). In Ré island, 27% of the specimens showed a nipped foot. Logistic regression shows that in D. trunculus length is the variable that most influences the probability of foot nipping, followed by weight and chlorophyll a. However, the difference in length between damaged and undamaged individuals was not significant (U-Mann-Whitney test). The size class frequency and the values of Ivlev's index show that the small size classes were avoided, while for the other size classes predation remained balanced throughout the year. Therefore, the avoidance of the small size classes makes length the most influential variable. The logistic regression indicated a coefficient B=-0.03 for weight. This implies a slightly negative influence on the probability of foot nipping. However, without the data of September, there is a positive correlation ( r=0.76, p<0.01) between the monthly percentages of predation and the flesh dry weight of a standard individual (25 mm long). The peak in September could be due to the recruitment peak of bivalves, which may have attracted more predators to the area, and/or to the recruitment of predators such as crabs to the swash zone. Logistic regression and test of comparison of percentages indicate that there was not any influence of the sex of an animal on the probability of foot nipping. Only in February was a significantly higher percentage ( p<0.05) of females nipped (44.44%) than the total of females in the sample (20.20%). The biomass (as flesh dry weight) of D. trunculus lost by foot nipping amounts to more than 20% in most of the size classes. There was an increase from the small sizes to the largest ones, in which it reaches 37%, with a positive correlation ( r=0.84; p<0.005) between size class and loss of biomass. Possible predators responsible for the foot nipping are crabs. Crab species usually found together with the donacids were Portumnus latipes (Pennant, 1777) Liocarcinus vernalis (Risso, 1816) and Atelecyclus undecimdentatus (Herbst, 1783). In aquarium experiments, they demonstrated an ability to nip the foot of clams. Portumnus latipes was the most active foot nipper, but left alive all the damaged clams. Therefore, we conclude that crabs are the most likely foot-nipping predators in the field.

Multiphase chemistry in a microphysical radiation fog model—A numerical study

NASA Astrophysics Data System (ADS)

Bott, Andreas; Carmichael, Gregory R.

A microphysical radiation fog model is coupled with a detailed chemistry module to simulate chemical reactions in the gas phase and in fog water during a radiation fog event. In the chemical part of the model the microphysical particle spectrum is subdivided into three size classes corresponding to non-activated aerosol particles, small and large fog droplets. Chemical reactions in the liquid phase are separately calculated in the small and in the large droplet size class. The impact of the chemical constitution of activated aerosols on fogwater chemistry is considered in the model simulations. The mass transfer of chemical species between the gas phase and the two liquid phases is treated in detail by solving the corresponding coupled differential equation system. The model also accounts for concentration changes of gas-phase and aqueous-phase chemical species which are induced by turbulence, gravitational settling and by evaporation/condensation processes. Numerical results demonstrate that fogwater chemistry is strongly controlled by dynamic processes, i.e. the vertical growth of the fog, turbulent mixing processes and the gravitational settling of the particles. The concentrations of aqueous-phase chemical species are different in the two droplet size classes. Reactands with lower water solubility are mainly found in the large droplet size class because the characteristic time for their mass transfer from the gas phase into the liquid phase is essentially longer than the characteristic time for the formation of large fog droplets. Species with high water solubility are rapidly transferred into the small fog droplets and are then washed out by wet deposition before these particles grow further to form large droplets. Thus, the concentrations of the major ions (NO 3-, NH 4+) are much higher in small than in large droplets, yielding distinctly lower pH values of the small particles. In the present study the reaction of sulfur with H 2O 2 and the Fe(III)-catalysed autoxidation of S(IV) are the major S(VI) producing mechanisms in fog water. Most of the time the sulfur oxidation rates are higher in the large than in the small droplets. Fogwater deposition by gravitational settling occurs mainly in the large droplet size class. However, since in the small droplets the concentrations of chemical species with very good water solubility are relatively high, in both droplet size classes the total wet deposition of these reactands is of the same order of magnitude.

Diagnostic accuracy of different display types in detection of recurrent caries under restorations by using CBCT.

PubMed

Baltacıoĝlu, İsmail H; Eren, Hakan; Yavuz, Yasemin; Kamburoğlu, Kıvanç

To assess the in vitro diagnostic ability of CBCT images using seven different display types in the detection of recurrent caries. Our study comprised 128 extracted human premolar and molar teeth. 8 groups each containing 16 teeth were obtained as follows: (1) Black Class I (Occlusal) amalgam filling without caries; (2) Black Class I (Occlusal) composite filling without caries; (3) Black Class II (Proximal) amalgam filling without caries; (4) Black Class II (Proximal) composite filling without caries; (5) Black Class I (Occlusal) amalgam filling with caries; (6) Black Class I (Occlusal) composite filling with caries; (7) Black Class II (Proximal) amalgam filling with caries; and (8) Black Class II (Proximal) composite filling with caries. Teeth were imaged using 100 × 90 mm field of view at three different voxel sizes of a CBCT unit (Planmeca ProMax(®) 3D ProFace™; Planmeca, Helsinki, Finland). CBCT TIFF images were opened and viewed using custom-designed software for computers on different display types. Intra- and interobserver agreements were calculated. The highest area under the receiver operating characteristic curve (Az) values for each image type, observer, reading and restoration were compared using z-tests against Az = 0.5. The significance level was set at p = 0.05. We found poor and moderate agreements. In general, Az values were found when software and medical diagnostic monitor were utilized. For Observer 2, Az values were statistically significantly higher when software was used on medical monitor [p = 0.036, p = 0.015 and p = 0.002, for normal-resolution mode (0.200 mm(3) voxel size), high-resolution mode (0.150 mm(3) voxel size) and low-resolution mode (0.400 mm(3) voxel size), respectively]. No statistically significant differences were found among other display types for all modes (p > 0.05). In general, no difference was found among 3 different voxel sizes (p > 0.05). In general, higher Az values were obtained for composite restorations than for amalgam restorations for all observers. For Observer 1, Az values for composite restorations were statistically significantly higher than those of amalgam restorations for MacBook and iPhone (Apple Inc., Cupertino, CA) assessments (p = 0.002 and p = 0.048, respectively). Higher Az values were observed with medical monitors when used with dedicated software compared to other display types which performed similarly in the diagnosis of recurrent caries under restorations. In addition, observers performed better in detection of recurrent caries when assessing composite restorations than amalgams.

Diagnostic accuracy of different display types in detection of recurrent caries under restorations by using CBCT

PubMed Central

Baltacıoĝlu, İsmail H; Eren, Hakan; Yavuz, Yasemin

2016-01-01

Objectives: To assess the in vitro diagnostic ability of CBCT images using seven different display types in the detection of recurrent caries. Methods: Our study comprised 128 extracted human premolar and molar teeth. 8 groups each containing 16 teeth were obtained as follows: (1) Black Class I (Occlusal) amalgam filling without caries; (2) Black Class I (Occlusal) composite filling without caries; (3) Black Class II (Proximal) amalgam filling without caries; (4) Black Class II (Proximal) composite filling without caries; (5) Black Class I (Occlusal) amalgam filling with caries; (6) Black Class I (Occlusal) composite filling with caries; (7) Black Class II (Proximal) amalgam filling with caries; and (8) Black Class II (Proximal) composite filling with caries. Teeth were imaged using 100 × 90 mm field of view at three different voxel sizes of a CBCT unit (Planmeca ProMax® 3D ProFace™; Planmeca, Helsinki, Finland). CBCT TIFF images were opened and viewed using custom-designed software for computers on different display types. Intra- and interobserver agreements were calculated. The highest area under the receiver operating characteristic curve (Az) values for each image type, observer, reading and restoration were compared using z-tests against Az = 0.5. The significance level was set at p = 0.05. Results: We found poor and moderate agreements. In general, Az values were found when software and medical diagnostic monitor were utilized. For Observer 2, Az values were statistically significantly higher when software was used on medical monitor [p = 0.036, p = 0.015 and p = 0.002, for normal-resolution mode (0.200 mm3 voxel size), high-resolution mode (0.150 mm3 voxel size) and low-resolution mode (0.400 mm3 voxel size), respectively]. No statistically significant differences were found among other display types for all modes (p > 0.05). In general, no difference was found among 3 different voxel sizes (p > 0.05). In general, higher Az values were obtained for composite restorations than for amalgam restorations for all observers. For Observer 1, Az values for composite restorations were statistically significantly higher than those of amalgam restorations for MacBook and iPhone (Apple Inc., Cupertino, CA) assessments (p = 0.002 and p = 0.048, respectively). Conclusions: Higher Az values were observed with medical monitors when used with dedicated software compared to other display types which performed similarly in the diagnosis of recurrent caries under restorations. In addition, observers performed better in detection of recurrent caries when assessing composite restorations than amalgams. PMID:27319604

The prevalence of domestic violence within different socio-economic classes in Central Trinidad.

PubMed

Nagassar, R P; Rawlins, J M; Sampson, N R; Zackerali, J; Chankadyal, K; Ramasir, C; Boodram, R

2010-01-01

Domestic violence is a medical and social issue that often leads to negative consequences for society. This paper examines the association between the prevalence of domestic violence in relation to the different socio-economic classes in Central Trinidad. The paper also explores the major perceived causes of physical abuse in Central Trinidad. Participants were selected using a two-stage stratified sampling method within the Couva district. Households, each contributing one participant, were stratified into different socioeconomic classes (SES Class) and each stratum size (or its share in the sample) was determined by the portion of its size in the sampling frame to the total sample; then its members were randomly selected. The sampling method attempted to balance and then minimize racial, age, cultural biases and confounding factors. The participant chosen had to be older than 16-years of age, female and a resident of the household. If more than one female was at home, the most senior was interviewed. The study found a statistically significant relationship between verbal abuse (p = 0.0017), physical abuse (p = 0.0012) and financial abuse (p = 0.001) and socio-economic class. For all the socio-economic classes considered, the highest prevalence of domestic violence occurred amongst the working class and lower middle socio-economic classes. The most prominent reasons cited for the physical violence was drug and alcohol abuse (37%) and communication differences (16.3%). These were the other two main perceived causes of the violence. The power of the study was 0.78 and the all strata prevalence of domestic violence was 41%. Domestic violence was reported within all socio-economic class groupings but it was most prevalent within the working class and lower middle socio-economic classes. The major perceived cause of domestic violence was alcohol/drug abuse.

Inter-class competition in stage-structured populations: effects of adult density on life-history traits of adult and juvenile common lizards.

PubMed

San-Jose, Luis M; Peñalver-Alcázar, Miguel; Huyghe, Katleen; Breedveld, Merel C; Fitze, Patrick S

2016-12-01

Ecological and evolutionary processes in natural populations are largely influenced by the population's stage-structure. Commonly, different classes have different competitive abilities, e.g., due to differences in body size, suggesting that inter-class competition may be important and largely asymmetric. However, experimental evidence states that inter-class competition, which is important, is rare and restricted to marine fish. Here, we manipulated the adult density in six semi-natural populations of the European common lizard, Zootoca vivipara, while holding juvenile density constant. Adult density affected juveniles, but not adults, in line with inter-class competition. High adult density led to lower juvenile survival and growth before hibernation. In contrast, juvenile survival after hibernation was higher in populations with high adult density, pointing to relaxed inter-class competition. As a result, annual survival was not affected by adult density, showing that differences in pre- and post-hibernation survival balanced each other out. The intensity of inter-class competition affected reproduction, performance, and body size in juveniles. Path analyses unravelled direct treatment effects on early growth (pre-hibernation) and no direct treatment effects on the parameters measured after hibernation. This points to allometry of treatment-induced differences in early growth, and it suggests that inter-class competition mainly affects the early growth of the competitively inferior class and thereby their future performance and reproduction. These results are in contrast with previous findings and, together with results in marine fish, suggest that the strength and direction of density dependence may depend on the degree of inter-class competition, and thus on the availability of resources used by the competing classes.

Embodiment of social roles and thinness as a form of capital: A qualitative approach towards understanding female obesity disparities in Chile.

PubMed

Robinovich, Jossiana; Ossa, Ximena; Baeza, Bernardita; Krumeich, Anja; van der Borne, Bart

2018-03-01

Obesity in Chile disproportionately affects women of low socioeconomic status (SES). Research has shown that ideals of body size and differences in perceived social pressure for being slim across socioeconomic strata contribute to the social stratification of body size among women in modern societies. Thinness is most valued by high SES women, following western standards of ideal body size. Aiming to understand the link between ideals of body size and SES, this qualitative study explored how 36 Chilean women construct their bodily ideals according to their social position. A purposive sample of women with different profiles with regard to educational attainment, nutritional status and body size (dis)satisfaction was defined, aiming to cover a diverse spectrum of bodily perceptions. Data were collected through semi-structured interviews and approached through a thematic and narrative analysis. Drawing on Bourdieu's concepts of habitus, field, capital and embodiment of the social context, this study explains how ideals of body size and appearance are strongly linked to class-dependent gender roles and social roles. The existing gender and class inequalities in the Chilean social structure have been literally embodied by these women through a 'gendered class habitus'. Compliance with the thin ideal confers women different degrees of power according to their social position in different fields, such as in marriage and on the labour market, which turns thinness into an embodied form of capital. The societal dynamic behind obesity rates cannot be disregarded when approaching possible solutions. Promoting obesity-related lifestyle modification at an individual level might appear an over-simplistic and individualistic approach to a complex social issue. Context-oriented interventions that take cultural constructions of gender and social class into account might yield better results in the long term, while advocating for a more equitable society and social justice as a public health concern. Copyright © 2018 Elsevier Ltd. All rights reserved.

Modulation of ovarian follicle maturation and effects on apoptotic cell death in Holtzman rats exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in utero and lactationally.

PubMed

Heimler, I; Trewin, A L; Chaffin, C L; Rawlins, R G; Hutz, R J

1998-01-01

Recent reports have described the reproduction-modulating and endocrine-disrupting effects following exposure to toxic substances such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Herein, we set out (1) to determine whether TCDD exposure exerts detrimental effects on follicle maturation in the Holtzman rat ovary and (2) to determine whether the effects of TCDD are mediated in part via apoptotic cell death. In certain species, dioxin exposure is correlated with reduced fecundity, reduced ovulatory rate, an increased incidence of endometriosis, and various reproductive cancers. Although some of the effects of TCDD are mediated via the hypothalamic-pituitary axis, direct effects on the ovary have also been observed. In the present study, an oral dose of 1 microgram TCDD/kg maternal body weight was administered on Day 15 of gestation. Female pups were sacrificed on Postnatal Day 21/22, and the ovaries were excised, fixed for histologic analysis, and analyzed in a double-blind paradigm. The analysis included a count and measurement and classification of preantral and antral follicles throughout the entire ovary. The contralateral ovary from each animal was analyzed for DNA fragmentation indicative of apoptotic cell death. The results indicate that TCDD treatment significantly reduced the number of antral follicles in the size classes 50,000 to 74,999 microns2 and > 100,000 microns2. We also observed a reduction in the number of preantral follicles less than 50,000 microns2. No difference was observed in the degree of apoptotic cell death in antral (50,000 to > 100,000 microns2) and preantral follicles (50,000 microns2 to > 75,000 microns2) between TCDD-treated and control-treated tissues. These data support the hypothesis that TCDD results in a diminution in the number of antral and preantral follicles of certain size classes in animals exposed during critical periods of development, but that apoptosis does not appear to be the underlying mechanism in these particular follicles. This does not preclude apoptosis occurring in pools of smaller precursor follicles.

Estimates of downed woody debris decay class transitions for forests across the eastern United States

Treesearch

Matthew B. Russell; Christopher W. Woodall; Shawn Fraver; Anthony W. D' Amato

2013-01-01

Large-scale inventories of downed woody debris (DWD; downed dead wood of a minimum size) often record decay status by assigning pieces to classes of decay according to their visual/structural attributes (e.g., presence of branches, log shape, and texture and color of wood). DWD decay classes are not only essential for estimating current DWD biomass and carbon stocks,...

A numerical rating system for crown classes of southern hardwoods

Treesearch

James S. Meadows; E.C. Burkhardt; Robert L. Johnson; John D. Hodges

2001-01-01

A numerical rating system to delineate crown classes of southern hardwoods is described. The system is based on four criteria: (1) amount of direct sunlight from above, (2) amount of direct sunlight from the sides, (3) crown balance, and (4) relative crown size. The total point value assigned places the tree within one of the four crown classes. The rating system can...

Active Learning and Just-in-Time Teaching in a Material and Energy Balances Course

ERIC Educational Resources Information Center

Liberatore, Matthew W.

2013-01-01

The delivery of a material and energy balances course is enhanced through a series of in-class and out-of-class exercises. An active learning classroom is achieved, even at class sizes over 150 students, using multiple instructors in a single classroom, problem solving in teams, problems based on YouTube videos, and just-in-time teaching. To avoid…

Deletion of Tsc2 in Nociceptors Reduces Target Innervation, Ion Channel Expression, and Sensitivity to Heat

PubMed Central

Carlin, Dan; Golden, Judith P.; Monk, Kelly R.

2018-01-01

Abstract The mechanistic target of rapamycin complex 1 (mTORC1) is known to regulate cellular growth pathways, and its genetic activation is sufficient to enhance regenerative axon growth following injury to the central or peripheral nervous systems. However, excess mTORC1 activation may promote innervation defects, and mTORC1 activity mediates injury-induced hypersensitivity, reducing enthusiasm for the pathway as a therapeutic target. While mTORC1 activity is required for full expression of some pain modalities, the effects of pathway activation on nociceptor phenotypes and sensory behaviors are currently unknown. To address this, we genetically activated mTORC1 in mouse peripheral sensory neurons by conditional deletion of its negative regulator Tuberous Sclerosis Complex 2 (Tsc2). Consistent with the well-known role of mTORC1 in regulating cell size, soma size and axon diameter of C-nociceptors were increased in Tsc2-deleted mice. Glabrous skin and spinal cord innervation by C-fiber neurons were also disrupted. Transcriptional profiling of nociceptors enriched by fluorescence-associated cell sorting (FACS) revealed downregulation of multiple classes of ion channels as well as reduced expression of markers for peptidergic nociceptors in Tsc2-deleted mice. In addition to these changes in innervation and gene expression, Tsc2-deleted mice exhibited reduced noxious heat sensitivity and decreased injury-induced cold hypersensitivity, but normal baseline sensitivity to cold and mechanical stimuli. Together, these data show that excess mTORC1 activity in sensory neurons produces changes in gene expression, neuron morphology and sensory behavior. PMID:29766046

Student evaluations of teaching: teaching quantitative courses can be hazardous to one’s career

PubMed Central

Smibert, Dylan

2017-01-01

Anonymous student evaluations of teaching (SETs) are used by colleges and universities to measure teaching effectiveness and to make decisions about faculty hiring, firing, re-appointment, promotion, tenure, and merit pay. Although numerous studies have found that SETs correlate with various teaching effectiveness irrelevant factors (TEIFs) such as subject, class size, and grading standards, it has been argued that such correlations are small and do not undermine the validity of SETs as measures of professors’ teaching effectiveness. However, previous research has generally used inappropriate parametric statistics and effect sizes to examine and to evaluate the significance of TEIFs on personnel decisions. Accordingly, we examined the influence of quantitative vs. non-quantitative courses on SET ratings and SET based personnel decisions using 14,872 publicly posted class evaluations where each evaluation represents a summary of SET ratings provided by individual students responding in each class. In total, 325,538 individual student evaluations from a US mid-size university contributed to theses class evaluations. The results demonstrate that class subject (math vs. English) is strongly associated with SET ratings, has a substantial impact on professors being labeled satisfactory vs. unsatisfactory and excellent vs. non-excellent, and the impact varies substantially depending on the criteria used to classify professors as satisfactory vs. unsatisfactory. Professors teaching quantitative courses are far more likely not to receive tenure, promotion, and/or merit pay when their performance is evaluated against common standards. PMID:28503380

Student evaluations of teaching: teaching quantitative courses can be hazardous to one's career.

PubMed

Uttl, Bob; Smibert, Dylan

2017-01-01

Anonymous student evaluations of teaching (SETs) are used by colleges and universities to measure teaching effectiveness and to make decisions about faculty hiring, firing, re-appointment, promotion, tenure, and merit pay. Although numerous studies have found that SETs correlate with various teaching effectiveness irrelevant factors (TEIFs) such as subject, class size, and grading standards, it has been argued that such correlations are small and do not undermine the validity of SETs as measures of professors' teaching effectiveness. However, previous research has generally used inappropriate parametric statistics and effect sizes to examine and to evaluate the significance of TEIFs on personnel decisions. Accordingly, we examined the influence of quantitative vs. non-quantitative courses on SET ratings and SET based personnel decisions using 14,872 publicly posted class evaluations where each evaluation represents a summary of SET ratings provided by individual students responding in each class. In total, 325,538 individual student evaluations from a US mid-size university contributed to theses class evaluations. The results demonstrate that class subject (math vs. English) is strongly associated with SET ratings, has a substantial impact on professors being labeled satisfactory vs. unsatisfactory and excellent vs. non-excellent, and the impact varies substantially depending on the criteria used to classify professors as satisfactory vs. unsatisfactory. Professors teaching quantitative courses are far more likely not to receive tenure, promotion, and/or merit pay when their performance is evaluated against common standards.

[Diet composition and ontogenetic variation in feeding habits of Cleithenes herzensteini in central Yellow Sea].

PubMed

Zhang, Bo

2007-08-01

In the bottom trawl surveys in central Yellow Sea from January 2004 to October 2005, 622 samples of plaice Cleithenes herzensteini were collected, and their stomach contents were analyzed. The results indicated that the prey items of the plaice included 11 groups or 38 prey species, but only Crustacea and Lamellibranchia were the most important prey groups, accounting for 99% of the total food composition by percentage of index of relative importance. Euphausia pacific, Crangon affinis and Tellinidae were the dominant prey species. Comparing with the 1980s, the feeding activity of plaice declined significantly, and the diet composition changed. Fishes were no longer the dominant prey, and the proportion of anchovy in the diet decreased. Cluster analysis and two-way contingency table analysis were used to study the ontogenetic variations in the feeding habits of plaice, and the results showed that the feeding activity of plaice did not vary significantly among 7 size classes within the size between 51 mm and 370 mm, but ontogenetic variations were found in the diet composition. In the size class < 119 mm, the diet mainly included Euphausiacea and Decapoda. In the diets of fish with the size between 120 mm and 199 mm, the proportion of Lamellibranchia and fishes increased markedly. In the size class > 200 mm, plaice mainly fed on Decapoda and fishes.

Optically-derived estimates of phytoplankton size class and taxonomic group biomass in the Eastern Subarctic Pacific Ocean

NASA Astrophysics Data System (ADS)

Zeng, Chen; Rosengard, Sarah Z.; Burt, William; Peña, M. Angelica; Nemcek, Nina; Zeng, Tao; Arrigo, Kevin R.; Tortell, Philippe D.

2018-06-01

We evaluate several algorithms for the estimation of phytoplankton size class (PSC) and functional type (PFT) biomass from ship-based optical measurements in the Subarctic Northeast Pacific Ocean. Using underway measurements of particulate absorption and backscatter in surface waters, we derived estimates of PSC/PFT based on chlorophyll-a concentrations (Chl-a), particulate absorption spectra and the wavelength dependence of particulate backscatter. Optically-derived [Chl-a] and phytoplankton absorption measurements were validated against discrete calibration samples, while the derived PSC/PFT estimates were validated using size-fractionated Chl-a measurements and HPLC analysis of diagnostic photosynthetic pigments (DPA). Our results showflo that PSC/PFT algorithms based on [Chl-a] and particulate absorption spectra performed significantly better than the backscatter slope approach. These two more successful algorithms yielded estimates of phytoplankton size classes that agreed well with HPLC-derived DPA estimates (RMSE = 12.9%, and 16.6%, respectively) across a range of hydrographic and productivity regimes. Moreover, the [Chl-a] algorithm produced PSC estimates that agreed well with size-fractionated [Chl-a] measurements, and estimates of the biomass of specific phytoplankton groups that were consistent with values derived from HPLC. Based on these results, we suggest that simple [Chl-a] measurements should be more fully exploited to improve the classification of phytoplankton assemblages in the Northeast Pacific Ocean.

Small Classes 1, Vouchers 0.

ERIC Educational Resources Information Center

Bracey, Gerald W.

2000-01-01

Alan Krueger's reanalyses of Eric Hanushek's school-productivity data show that Hanushek's "money doesn't matter" conclusions (influential in several states' education-finance hearings) have no factual basis. Hanushek excluded Tennessee's student/teacher ratio study (Project STAR). Also, class size is influencing students' success in…

The influence of simulated exploitation on Patella vulgata populations: protandric sex change is size-dependent.

PubMed

Borges, Carla D G; Hawkins, Stephen J; Crowe, Tasman P; Doncaster, C Patrick

2016-01-01

Grazing mollusks are used as a food resource worldwide, and limpets are harvested commercially for both local consumption and export in several countries. This study describes a field experiment to assess the effects of simulated human exploitation of limpets Patella vulgata on their population ecology in terms of protandry (age-related sex change from male to female), growth, recruitment, migration, and density regulation. Limpet populations at two locations in southwest England were artificially exploited by systematic removal of the largest individuals for 18 months in plots assigned to three treatments at each site: no (control), low, and high exploitation. The shell size at sex change (L 50: the size at which there is a 50:50 sex ratio) decreased in response to the exploitation treatments, as did the mean shell size of sexual stages. Size-dependent sex change was indicated by L 50 occurring at smaller sizes in treatments than controls, suggesting an earlier switch to females. Mean shell size of P. vulgata neuters changed little under different levels of exploitation, while males and females both decreased markedly in size with exploitation. No differences were detected in the relative abundances of sexual stages, indicating some compensation for the removal of the bigger individuals via recruitment and sex change as no migratory patterns were detected between treatments. At the end of the experiment, 0-15 mm recruits were more abundant at one of the locations but no differences were detected between treatments. We conclude that sex change in P. vulgata can be induced at smaller sizes by reductions in density of the largest individuals reducing interage class competition. Knowledge of sex-change adaptation in exploited limpet populations should underpin strategies to counteract population decline and improve rocky shore conservation and resource management.

Headgear Accessories Classification Using an Overhead Depth Sensor

PubMed Central

Luna, Carlos A.; Marron-Romera, Marta; Mazo, Manuel; Luengo-Sanchez, Sara; Macho-Pedroso, Roberto

2017-01-01

In this paper, we address the generation of semantic labels describing the headgear accessories carried out by people in a scene under surveillance, only using depth information obtained from a Time-of-Flight (ToF) camera placed in an overhead position. We propose a new method for headgear accessories classification based on the design of a robust processing strategy that includes the estimation of a meaningful feature vector that provides the relevant information about the people’s head and shoulder areas. This paper includes a detailed description of the proposed algorithmic approach, and the results obtained in tests with persons with and without headgear accessories, and with different types of hats and caps. In order to evaluate the proposal, a wide experimental validation has been carried out on a fully labeled database (that has been made available to the scientific community), including a broad variety of people and headgear accessories. For the validation, three different levels of detail have been defined, considering a different number of classes: the first level only includes two classes (hat/cap, and no hat/cap), the second one considers three classes (hat, cap and no hat/cap), and the last one includes the full class set with the five classes (no hat/cap, cap, small size hat, medium size hat, and large size hat). The achieved performance is satisfactory in every case: the average classification rates for the first level reaches 95.25%, for the second one is 92.34%, and for the full class set equals 84.60%. In addition, the online stage processing time is 5.75 ms per frame in a standard PC, thus allowing for real-time operation. PMID:28796177

Effect of lecture instruction on student performance on qualitative questions

NASA Astrophysics Data System (ADS)

Heron, Paula R. L.

2015-06-01

The impact of lecture instruction on student conceptual understanding in physics has been the subject of research for several decades. Most studies have reported disappointingly small improvements in student performance on conceptual questions despite direct instruction on the relevant topics. These results have spurred a number of attempts to improve learning in physics courses through new curricula and instructional techniques. This paper contributes to the research base through a retrospective analysis of 20 randomly selected qualitative questions on topics in kinematics, dynamics, electrostatics, waves, and physical optics that have been given in introductory calculus-based physics at the University of Washington over a period of 15 years. In some classes, questions were administered after relevant lecture instruction had been completed; in others, it had yet to begin. Simple statistical tests indicate that the average performance of the "after lecture" classes was significantly better than that of the "before lecture" classes for 11 questions, significantly worse for two questions, and indistinguishable for the remaining seven. However, the classes had not been randomly assigned to be tested before or after lecture instruction. Multiple linear regression was therefore conducted with variables (such as class size) that could plausibly lead to systematic differences in performance and thus obscure (or artificially enhance) the effect of lecture instruction. The regression models support the results of the simple tests for all but four questions. In those cases, the effect of lecture instruction was reduced to a nonsignificant level, or increased to a significant, negative level when other variables were considered. Thus the results provide robust evidence that instruction in lecture can increase student ability to give correct answers to conceptual questions but does not necessarily do so; in some cases it can even lead to a decrease.

Fossil and genetic history of a pinyon pine (Pinus edulis) isolate

USGS Publications Warehouse

Betancourt, J.L.; Schuster, W.S.; Mitton, J.B.; Anderson, R. Scott

1991-01-01

The most isolated northern stand of Colorado pinyon pine at Owl Canyon, Colorado, has a broad and flat size class distribution common to population expansions, with the largest and oldest trees near the center of the grove. Analyses of fossil packrat Neotoma middens within the grove indicate that the stand originated by long-distance dispersal rather than by vicariance. The 5000-yr pollen and macrofossil record suggests that pinyon pine colonized the site sometime between 1290-420 yr BP, the latter age corresponding to the oldest tree in the stand. Electrophoretic data show that this colonization was not attended by typical founder effects predicted by theory or observed for other known founder events. The Owl Canyon stand has not suffered significant losses in genetic variation relative to likely source populations. Large initial population size, multiple founding events, rapid population growth, or selection favoring heterozygous genotypes could all explain the high heterozygosity and only slightly reduced polymorphism and number of alleles per locus. -from Authors

Aeration costs in stirred-tank and bubble column bioreactors

DOE PAGES

Humbird, D.; Davis, R.; McMillan, J. D.

2017-08-10

To overcome knowledge gaps in the economics of large-scale aeration for production of commodity products, Aspen Plus is used to simulate steady-state oxygen delivery in both stirred-tank and bubble column bioreactors, using published engineering correlations for oxygen mass transfer as a function of aeration rate and power input, coupled with new equipment cost estimates developed in Aspen Capital Cost Estimator and validated against vendor quotations. Here, these simulations describe the cost efficiency of oxygen delivery as a function of oxygen uptake rate and vessel size, and show that capital and operating costs for oxygen delivery drop considerably moving from standard-sizemore » (200 m 3) to world-class size (500 m 3) reactors, but only marginally in further scaling up to hypothetically large (1000 m 3) reactors. Finally, this analysis suggests bubble-column reactor systems can reduce overall costs for oxygen delivery by 10-20% relative to stirred tanks at low to moderate oxygen transfer rates up to 150 mmol/L-h.« less

Green synthesis of copper oxide (CuO) nanoparticles using banana peel extract and their photocatalytic activities

NASA Astrophysics Data System (ADS)

Aminuzzaman, Mohammod; Kei, Leong Mei; Liang, Wong Hong

2017-04-01

Copper oxide nanoparticles (CuO NPs) are interesting class of materials having multifunctional properties with promising applications in the areas of catalysts, gas sensors, batteries, magnetic storage media, solar energy, superconductors etc. Thus synthesis of CuO NPs has attracted tremendous interest to scientists and researchers Herein, we reported a green and simple method for biosynthesizing CuO NPs using banana peel extract as reducing and stabilizing agent. XRD, EDX, FE-SEM, FTIR have been used for characterization of biosynthesized CuO NPs. The results indicating that the CuO NPs synthesized by banana peel extract have high purity and the average particles size is 60 nm. The photocatalytic activity of the CuO NPs has been investigated by degradation of Congo red (CR) dye under solar irradiation. The extent of CR dye degradation by CuO NPs is monitored by using a UV-visible spectrophotometer. Due to the smaller size and high purity, the biosynthesized CuO NPs showed an excellent photocatlytic activity.