396 research outputs found
Building on the cultural and linguistic capital of English learner (EL) students
Approaches and strategies that value and build upon the cultural and linguistic capital of English learner students are described. Through implementing such strategies, teachers can impress upon students and families that multiculturalism and multilingualism are highly beneficial to the classroom, school, and community
Invasive species Lemna L. (Lemnaceae) in the flora of Bulgaria
Background and Purpose: During the investigations of flora of Bulgaria new species from genus Lemna have been found in Bulgaria.
Materials and methods: They were conducted during the period 2010 - 2015 for which purpose we explored diverse pools in different parts of Bulgaria (hot and cold swamps, spillages of rivers and streams, hot mineral waters). The species were determined by Flora of North America.
Results: In the flora of Bulgaria we found the following new (invasive) species L. minuta KUNTH., L. obscura (AUSTIN) Daubs, L. perpusilla TORR. and L. valdiviana PHILIPI. Their morphology, chorology and ecology was recorded and data about the accompanying species are also given.
Conclusion: Finding these Lemna species in several distant locations in our country is a clear indication that the species is transferred on the territory of Bulgaria a long time ago. The species are most likely invading from neighboring fields in Southeast Europe - Greece, Romania, Turkey and others
Review of the Statistical Analytical Techniques for the Optimization of Ultrahigh Pressure for Extracting Biologically Active Compounds
Biologically Active Compounds (BACs) are organic compounds that are rich in nutrients and have characteristics such as anti-hypertensive, anti-cancer, and antioxidant properties. When compared to conventional extraction methods, such as Soxhlet extraction, percolation, maceration, it takes a longer amount of time, resulting in lower percent yields, and the BACs are exposed to higher temperatures which might cause damage to the BACs when extracted. This review includes the factors that researchers have looked at are: temperature, pressure, the solvent to pomace ratio, and solvent effects which will allow us to better analyze the % yield of BACs extracted and optimize the procedure. The focus of this project is to review the statistical methods for studying the technique of ultra-high-pressure extraction of BACs from pomace (food waste). In conclusion, the multivariate statistic technique such as response surface methodology (RSM), has advantages to classical one-variable-a-time optimization, such as the generation of large amounts of information from a small number of experiments and the possibility of evaluating the interaction effect between the variables on the response
Ahedo, J., Caro, C. y Fuentes, J. L. (Coords.) (2021). Cultivar el carácter en la familia: una tarea ineludible. Madrid, Dykinson, 176 pp. [RECENSIÓN]
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Gender Diversity in the Aviation Workplace
In the past 90 years, the workforce has been diversified in many fields yet gender diversity for occupations in the aviation domain (e.g., pilots, air traffic controllers, aircraft maintenance technicians) has grown slowly. To explore this issue, the objective of this archival study was to examine the increase in the number of females and males from 2005 to 2018 for six aviation occupations in the private sector (civilian) in the United States: aircraft pilot and flight engineer; air traffic controller and airfield operations specialist; aerospace engineer; avionics technician; aircraft mechanic and service technician; and aircraft structure, surfaces, rigging, and systems assembler. Data were obtained from the American Community Survey using Public Use Microdata Sample from the United States Census Bureau. Results revealed females still comprise a very small percentage of the total workforce across aviation occupations. Change across the years was shown to be more erratic for females, compared to males. Further research is warranted to investigate the underlying causes for these erratic trends in the female aviation workforce in order to help solve the severe labor shortage affecting the entire aviation industry. Keywords: aviation, diversity, gender, labor shortag
Stem cell: from basic theoretical assumptions and mathematical concepts to the computational models
Morphophyziological and Anatomical Characteristics of Leaves in Accessions of Wild Einkorn (Triticum boeoticum Boiss.)
The aim of this study was to assess the degree of variation between 32 accessions of wild einkorn (Triticum boeoticum Boiss.) on the basic morphophysiological and anatomical characteristics of the flag and subflag leaves. The experiment was carried out during 2016 – 2017 growing seasons in the randomized block design in four replications and 10 m2 plot size. Significant differences among the accessions for all studied characters were recorded. The epidermis of the studied 32 accessions was constructed by strongly elongated prosenhyme cells with flexous walls. The stomatas were with oval to elliptic shape, about 1.5 times longer than wide. The most variable character was the total chlorophyll content. Accessions with numbers B6E0416, B6E0413, B6E0398 and B6E0392 had the largest amount of chlorophyll pigments exceeding the average standard almost twice. The water-to-biomass ratio in the flag leaf was the greatest for B6E0378, B6E0389 and B6E0401, while for the subflag leaves B6E0379, B6E0401 and B6E0385 were with the highest amount of water per unit of dry mass. The correlation between intensity of transpiration and the fresh and dry mass of leaves were slightly negative for flag leaf and slightly positive for subflag leaf. The water content of the subflag leaf had a stronger influence on the morphophysiological parameters compared to the water content of the flag leaf. PC-analysis grouped accessions according to similarity on the basis of investigated morphophysiological and physiological characters in two components in the factor plane
Joint models with multiple longitudinal outcomes and a time-to-event outcome: a corrected two-stage approach
Joint models for longitudinal and survival data have gained a lot of attention in recent years, with the development of myriad extensions to the basic model, including those which allow for multivariate longitudinal data, competing risks and recurrent events. Several software packages are now also available for their implementation. Although mathematically straightforward, the inclusion of multiple longitudinal outcomes in the joint model remains computationally difficult due to the large number of random effects required, which hampers the practical application of this extension. We present a novel approach that enables the fitting of such models with more realistic computational times. The idea behind the approach is to split the estimation of the joint model in two steps: estimating a multivariate mixed model for the longitudinal outcomes and then using the output from this model to fit the survival submodel. So-called two-stage approaches have previously been proposed and shown to be biased. Our approach differs from the standard version, in that we additionally propose the application of a correction factor, adjusting the estimates obtained such that they more closely resemble those we would expect to find with the multivariate joint model. This correction is based on importance sampling ideas. Simulation studies show that this corrected two-stage approach works satisfactorily, eliminating the bias while maintaining substantial improvement in computational time, even in more difficult settings
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