223 research outputs found
Judicial activism : a study of the Warren through Rehnquist courts.
Despite the dismissive attitude toward the concept of judicial activism among some members of the academic community, it nevertheless continues to be a relevant theme in politics. Conservatives tend to use this phrase as an attack on âliberalâ decisions that sacrifice principles in the name of expediency. This thesis challenges the concept that it is primarily liberal justices who are activist. I examine the activism levels of individual justices to ascertain which ideology, liberal or conservative, is more activist. Using the well-known Spaeth database, I evaluated all of the justices from the Warren through Rehnquist Courts by measuring three types of activism: federal-statute, state-statute, and altering precedent. The results show members of both ideologies engaging in activism
Geometric morphometric analysis as a tool to explore covariation between shape and other quantitative leaf traits in European white oaks
In this study, 2-Block Partial Least-Squares analysis was used to
explore the pattern of covariation between two sets of leaf morphological data
(landmarks and traditional measures), sampled on 273 trees in a mixed forest
of Quercus frainetto, Q. petraea and Q. pubescens, in southern-central Italy.
Two groups of related variables were detected and the three oak species were
highly significant discriminated by CVA computed on dimensions extracted by
2B-PLS analysis. Q. frainetto was characterized by obovate leaf blade with a
short petiole and leaves were greater than in the other species. Q. petraea
was differentiated by acute basal and apical regions, while Q. pubescens has
higher values of leaf compactness, pubescence and length of trichomes. The
high degree of classification accuracy of this combined approach advocates
its extension to other problematic species and highlights its importance as an
exploratory tool in plant ecology, physiology and taxonomy
Mentoring Women: Identifying, Developing, and Retaining STEM Stars
Women have made significant strides towards gender equality, particularly in education completion and labor force participation rates. Women make up about half of the total population in the United States, receive 57% of the awarded undergraduate degree as of 2010, and are evenly represented in STEM education, earning 50% of STEM bachelor degrees in 2012 (The World Bank Group, 2014; AAUW, n.d.; The National Science Foundation, 2015). Nevertheless, when it comes to translating their STEM degrees to the workforce, women remain seriously under-represented in both jobs held, and in leadership positions. This raises interesting questions about the relationship between education and work-place practices that might be pushing women out of STEM fields, and those supporting women to stay. This study is a focus on the latter, particularly looking at the role of mentoring in professional stem fields. Drawing on literature from women in leadership, gender and STEM, and mentoring in the workplace, this study specifically asks what relationship formal mentoring has to women's career trajectory in STEM fields, and more specifically, how mentoring relationships are formed, how they change over time, how mentoring impacts career development and what significance these factors have on retention of women as STEM stars.Ed.D., Educational Leadership and Management -- Drexel University, 201
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Siberian-Arctic shelf surface-sediments: sources, transport pathways and processes, and diagenetic alteration
This thesis investigates lithogenic sediments on the Siberian Arctic shelf, their sources, modes of dispersal, transport pathways and post-depositional diagenetic alteration. Working with cores collected from the Chukchi, East Siberian and Laptev Seas, we characterize surface-sediment elemental chemistry and clay mineralogy. We identify five regions with endmember sedimentary compositions. Comparing these data with a variety of geological, physical oceanographic and other environmental observations, we conclude that endmember formation is controlled by a complex combination of sediment provenance and various physical processes.
Average sediment transport pathways are inferred from gradients in geochemical endmember flux distributions. On the Chukchi shelf sediment movement is primarily offshore. In the alongshore direction, available data suggest that sediment dispersal is predominately to the east in both the Chukchi and Laptev Seas. These results corroborate the limited observations of shelf currents and suggest circulation is key in determining dominant sediment transport pathways. In the Laptev Sea, offshore sediment movement is limited compared to alongshore sediment movement. This sedimentation pattern may be controlled by currents, or by removal of sediment from the central Laptev shelf via ice rafting. A fraction of the material deposited on the shelf is recycled to overlying waters by sediment diagenesis. Chukchi surface sediments are typically depleted in Mn and Co relative to values predicted based on sediment source rock geology. Evaluating these metal depletions in the context of shelf primary production gradients and surface sediment color observations, we conclude they are caused by dissolved metal fluxes from suboxic surface sediments to overlying waters. We estimate that sediments within our Chukchi study area release 4.5-6.1 x 1Oâ´ tons/yr of dissolved Mn. Less than 1/20th of this Mn is sequestered as reactive Mn in lower Chukchi slope and Canadian basin sediments. Reactive Mn deposition throughout the Amerasian Arctic at depths >1000 m can potentially account for only about half of this Mn, indicating additional sinks exist for the dissolved Mn released from shelf sediments. Possible fates include 1) deposition as reactive Mn in upper slope sediments and 2) export from the region dissolved in Amerasian Arctic waters
Proteomic analysis of apricot fruit during ripening
Ripening of climacteric fruits involves a complex network of biochemical and metabolic
changes that make them palatable and rich in nutritional and health-beneficial compounds.
Since fruit maturation has a profound impact on human nutrition, it has been
recently the object of increasing research activity by holistic approaches, especially on
model species. Here we report on the original proteomic characterization of ripening in
apricot, a widely cultivated species of temperate zones appreciated for its taste and aromas,
whose cultivation is yet hampered by specific limitations. Fruits of Prunus armeniaca
cv. Vesuviana were harvested at three ripening stages and proteins extracted and resolved
by 1D and 2D electrophoresis. Whole lanes from 1D gels were subjected to shot-gun analysis
that identified 245 gene products, showing preliminary qualitative differences between
maturation stages. In parallel, differential analysis of 2D proteomic maps highlighted 106
spots as differentially represented among variably ripen fruits. Most of these were further
identified by means of MALDI-TOF-PMF and nanoLCâESIâLITâMS/MS as enzymes involved
in main biochemical processes influencing metabolic/structural changes occurring during
maturation, i.e. organic acids, carbohydrates and energy metabolism, ethylene biosynthesis,
cell wall restructuring and stress response, or as protein species linkable to peculiar
fruit organoleptic characteristics. In addition to originally present preliminary information
on the main biochemical changes that characterize apricot ripening, this study also
provides indications for future marker-assisted selection breeding programs aimed to
ameliorate fruit quality
Lentils biodiversity: the characterization of two local landraces
A multi-disciplinary approach was used to characterize two
autochthonous lentil landraces from Molise region (Central Italy). Different
mature seed populations for each landrace were provided by the Molise
Germoplasm Bank at the University of Molise (Pesche, Italy), and analyzed
at the morphological and molecular (DNA and protein) levels. Nuclear ISSR
markers were used to assess genetic differences, whereas phenotypic
variability was detected by biochemical (proteomics) and morphological
analyses. The genetic and phenotypic diversity of the two lentil landraces
were well assessed in relation to their geographical provenance, supporting
further studies to identify landrace markers
Rings without a lord? Enigmatic fossils from the lower Palaeozoic of Bohemia and the Carnic Alps
Fossilized ring-like structures, whose function and taxonomic affiliation are enigmatic, were recovered for the first time from the Upper Ordovician of the Carnic Alps and the Silurian of Bohemia. These rings, already mentioned as minor constituents in previous conodont studies (e.g., Webers 1966; Bischoff 1973), were reported from the Palaeozoic of several regions in Europe and North America. Originally considered as inwardly accreted adhering discs of a benthic Hyolithelminth worm with a phosphatic tubular projection, they were later reinterpreted in relation to a putative crinoid epibiont or even as possible Scyphozoans. Despite a long debate, neither the function of the enigmatic Palaeozoic rings nor their taxonomic affiliation have been fully clarified.The study material, extracted with a standard technique in use for conodonts, consists of 235 elements from 16 stratigraphic levels in the PlĂścken Formation (Carnic Alps, Cellon Section; Amorphognathus ordovicicus Biozone, Hirnantian, Ordovician) and in the Kopanina Formation (Bohemia, MuĹĄlovka Quarry; Polygnathoides siluricus Biozone, Ludfordian, Silurian). To explore whether ring size and shape changed over time, we employed a novel combination of geometric morphometric approaches for outlines with no 'homologous' landmarks and showed that only size appreciably varied with an increase of ca. 20%.The emerging data from this study are consistent with the interpretation of the rings as an adhering structure of a benthic organism living on a relatively uniform hard substrate
Leaf Morphology, Taxonomy and Geometric Morphometrics: A Simplified Protocol for Beginners
Taxonomy relies greatly on morphology to discriminate groups. Computerized geometric morphometric methods for quantitative shape analysis measure, test and visualize differences in form in a highly effective, reproducible, accurate and statistically powerful way. Plant leaves are commonly used in taxonomic analyses and are particularly suitable to landmark based geometric morphometrics. However, botanists do not yet seem to have taken advantage of this set of methods in their studies as much as zoologists have done. Using free software and an example dataset from two geographical populations of sessile oak leaves, we describe in detailed but simple terms how to: a) compute size and shape variables using Procrustes methods; b) test measurement error and the main levels of variation (population and trees) using a hierachical design; c) estimate the accuracy of group discrimination; d) repeat this estimate after controlling for the effect of size differences on shape (i.e., allometry). Measurement error was completely negligible; individual variation in leaf morphology was large and differences between trees were generally bigger than within trees; differences between the two geographic populations were small in both size and shape; despite a weak allometric trend, controlling for the effect of size on shape slighly increased discrimination accuracy. Procrustes based methods for the analysis of landmarks were highly efficient in measuring the hierarchical structure of differences in leaves and in revealing very small-scale variation. In taxonomy and many other fields of botany and biology, the application of geometric morphometrics contributes to increase scientific rigour in the description of important aspects of the phenotypic dimension of biodiversity. Easy to follow but detailed step by step example studies can promote a more extensive use of these numerical methods, as they provide an introduction to the discipline which, for many biologists, is less intimidating than the often inaccessible specialistic literature
Phenotypic plasticity in haptoral structures of Ligophorus cephali (Monogenea: Dactylogyridae) on the flathead mullet (Mugil cephalus): A Geometric Morphometric Approach
Evaluating phenotypic plasticity in attachment organs of parasites can provide information on the capacity to colonise new hosts and illuminate evolutionary processes driving host specificity. We analysed the variability in shape and size of the dorsal and ventral anchors of Ligophorus cephali from Mugil cephalus by means of geometric morphometrics and multivariate statistics. We also assessed the morphological integration between anchors and between the roots and points in order to gain insight into their functional morphology. Dorsal and ventral anchors showed a similar gradient of overall shape variation, but the amount of localised changes was much higher in the former. Statistical models describing variations in shape and size revealed clear differences between anchors. The dorsal anchor/bar complex seems more mobile than the ventral one in Ligophorus, and these differences may reflect different functional roles in attachment to the gills. The lower residual variation associated with the ventral anchor models suggests a tighter control of their shape and size, perhaps because these anchors seem to be responsible for firmer attachment and their size and shape would allow more effective responses to characteristics of the microenvironment within the individual host. Despite these putative functional differences, the high level of morphological integration indicates a concerted action between anchors. In addition, we found a slight, although significant, morphological integration between roots and points in both anchors, which suggests that a large fraction of the observed phenotypic variation does not compromise the functional role of anchors as levers. Given the low level of genetic variation in our sample, it is likely that much of the morphological variation reflects host-driven plastic responses. This supports the hypothesis of monogenean specificity through host-switching and rapid speciation. The present study demonstrates the potential of geometric morphometrics to provide new and previously unexplored insights into the functional morphology of attachment and evolutionary processes of hostÂżparasite coevolution
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