44 research outputs found

    Atlas of reflectance spectra of terrestrial, lunar and meteoritic powders and frosts from 92 to 1800 nm

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    The reflectance spectra of powdered samples of selected minerals, meteorites, lunar materials and frosts are presented as an aid in the interpretation of present and future remote sensing data of solar system objects. Spectra obtained in separate wavelength regions have been combined and normalized, yielding coverage from 92 to 1800 nm. Spectral features include reflectance maxima in the far UV region produced by valence-conduction interband transitions, and reflectance minima in the near UV, visible and near IR regions, produced by charge transfer and crystal field transitions. Specific maxima and minima are diagnostic of mineral type and composition; additionally, the minerals present in mixtures such as meteorites and lunar samples can be determined

    Perceptions of African American Male Students Enrolled in Developmental Education Programs in the Community College

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    This study sought to understand the perceptions of African American male students who are enrolled in developmental education programs. The researcher gathered information by interviewing students at 2 Mississippi community colleges and by reviewing information collected from the student’s demographic profile. This qualitative research allowed the researcher to learn directly from students, factors that contribute to African American male students developing a negative perception of developmental education programs. Participants were 20 African American male students enrolled in developmental education program in 2 Mississippi community colleges. Data collection occurred during the spring and fall 2016 semester. Each participant was asked 12 questions to determine his perspectives of developmental education programs and factors contributing to the student’s academic success. Moreover, the study provided solutions that can help dispel the negative perceptions of African American male students and suggested strategies for academic achievement. The factors included the following: support of community college leaders, supportive instructors, and peer support group. Data suggested that to support the academic success of African American male students, an understanding of their culture can benefit their advancement in the community college. The participants believe that if instructors would not give into the negative stereotypes and increase their willingness to go the extra mile to insure that African American male students become successful, the negative perception of developmental education program will change. Participants conveyed the need to feel cared for, understood, and supported by instructors and community college leaders. The findings from this study can assist community college leaders and instructors to develop educational interventions that will support African American male students. This research study is an attempt to provide information that will improve academic success of African American males enrolled in developmental educational programs in the community colleges

    Traction Characteristics of Prepared Traffic Lanes

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    Traction characteristics of lugged and smooth tires were compared on prepared traffic lanes and on conventional seedbed conditions. Results indicated that elevated traffic lanes offer important traction advantages over seedbeds in wet soil conditions. In dry soil conditions, traction on elevated traffic lanes was sometimes less than on the seedbed conditions. A timeliness advantage in mobility for the elevated traffic lanes was found to be up to 2 days in extremely wet conditions. A non-elevated traffic lane showed no traction advantage in wet conditions

    Appetitive reversal learning differences of two honey bee subspecies with different foraging behaviors

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    We aimed to examine mechanistically the observed foraging differences across two honey bee, Apis mellifera, subspecies using the proboscis extension response assay. Specifically, we compared differences in appetitive reversal learning ability between honey bee subspecies: Apis mellifera caucasica (Pollman), and Apis mellifera syriaca (Skorikov) in a “common garden” apiary. It was hypothesized that specific learning differences could explain previously observed foraging behavior differences of these subspecies: A.m. caucasica switches between different flower color morphs in response to reward variability, and A.m. syriaca does not switch. We suggest that flower constancy allows reduced exposure by minimizing search and handling time, whereas plasticity is important when maximizing harvest in preparation for long winter is at a premium. In the initial or Acquisition phase of the test we examined specifically discrimination learning, where bees were trained to respond to a paired conditioned stimulus with an unconditioned stimulus and not to respond to a second conditioned stimulus that is not followed by an unconditioned stimulus. We found no significant differences among the subspecies in the Acquisition phase in appetitive learning. During the second, Reversal phase of the experiment, where flexibility in association was tested, the paired and unpaired conditioned stimuli were reversed. During the Reversal phase A.m. syriaca showed a reduced ability to learn the reverse association in the appetitive learning task. This observation is consistent with the hypothesis that A.m. syriaca foragers cannot change the foraging choice because of lack of flexibility in appetitive associations under changing contingencies. Interestingly, both subspecies continued responding to the previously rewarded conditioned stimulus in the reversal phase. We discuss potential ecological correlates and molecular underpinnings of these differences in learning across the two subspecies. In addition, in a supplemental experiment we demonstrated that these differences in appetitive reversal learning do not occur in other learning contexts.National Science Foundation (NSF)Publisher's Versio

    A global corporate census: publicly traded and close companies in 1910

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    In 1910 the world had almost half a million corporations, only one-hundredth of today's total. About one-fifth—with over half of corporate capital—were publicly tradable, higher portions than today. Most publicly quoted corporations traded in Europe and the British Empire, but most close (private) corporations operated in the US, which, until the 1940s, had more corporations per capita than anywhere else. The 83 countries surveyed here differed markedly in company numbers, corporate capital/GDP ratios, and average corporate size. Enclave economies—dominated by quoted (and often foreign-owned) companies—had the largest average sizes, while other nations had more varied mixes of large quoted corporations and close company small and medium enterprises

    Australian non-perennial rivers: Global lessons and research opportunities

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    Non-perennial rivers are valuable water resources that support millions of humans globally, as well as unique riparian ecosystems. In Australia, the Earth’s driest inhabited continent, over 70% of rivers are non-perennial due to a combination of ancient landscape, dry climates, highly variable rainfall regimes, and human interventions that have altered riverine environments. Here, we review Australian non-perennial river research incorporating geomorphology, hydrology, biogeochemistry, ecology, and Indigenous knowledges. The dominant research themes in Australia were drought, floods, salinity, dryland ecology, and water management. Future research will likely follow these themes but must address emerging threats to river systems due to climate change and other anthropogenic impacts. Four high level opportunities for future research are identified, namely: (1) integrating Indigenous and western scientific knowledge; (2) quantifying climate change impacts on hydrological and biological function; (3) clarifying the meaning and measurement of “restoration” of non-perennial systems; and (4) understanding the role of groundwater. These challenges will require inter- and multi-disciplinary efforts supported by technological advances. The evolving body of knowledge about Australian rivers provides a foundation for comparison with other dryland areas globally where recognition of the importance of non-perennial rivers is expanding

    Finishing the euchromatic sequence of the human genome

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    The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

    A colony defence difference between two honey bee subspecies (Apis mellifera cypria and Apis mellifera cacasica)

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    Colony defence differences between two honey bee subspecies Apis mellifera cypria and A. m. caucasica are reported. A. m. cypria formed significantly (P 0.10). In addition to ball formation, A. m. cypria was tested for differences in frequency of attacking, shaking, shimmering, line formation and lunging when confronted with a live tethered wasp, dead tethered wasp or just the tethering line. Only the dead wasp elicited differential response. It is suggested that these difference in anti-predator behaviour are related to the high predation risks of A. m. cyrpria. Caucasian bees and their hybrids do not face to such wasp predation due to the cool weather in the Caucasus region.National Science Foundation (NSF) - DBI 055271
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