567 research outputs found
Using Linked Data for Prosopographical Research of Historical Persons : Case U.S. Congress Legislators
This paper shows how biographical registries can be represented as Linked Data, enriched by data linking to related data sources, and used in Digital Humanities. As a use case, a database of 11 987 historical U.S. Congress Legislators in 1789–2018 was transformed into a knowledge graph. The data was published as a Linked Data service, including a SPARQL endpoint, on top of which tools for biographical and prosopographical research are implemented. A faceted browser named U.S. Congress Prosopographer with visualization tools for knowledge discovery is presented to provide new insights in political history.Peer reviewe
Reciprocal peer coaching: A constructivist methodology for enhancing formative assessment strategy in tertiary education
Reciprocal peer coaching (RPC) as a form of peer-assisted learning has an important part to play in formative assessment strategy. The primary objective of this article is to evaluate the effective use of RPC as a formative assessment strategy. A multi-method phenomenological research design was employed using purposive sampling. Seventy students completed a qualitative focused questionnaire survey asking them to reflect on their experiences of reciprocal peer-coaching relationships. Content analysis of student perceptions resulted in the emergence of key themes including; RPC relationship process, the learning process and cognitive skills development. Powerful learning gains were reported by participants, and were characteristic of a successful RPC relationships. Overall the RPC relationship can greatly enhance deep level learning and aid the transfer of theory into practice to inform academic debate on the use of constructivist methodology for enhancing the use of formative assessment strategy within undergraduate business education
Growth and reproductive characteristics of C4 weeds under climatic conditions of the Czech Republic
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The stellar content of low redshift radio galaxies from near-infrared spectroscopy
We present medium spectral resolution near-infrared (NIR) HK-band spectra for
8 low redshift (z<0.06) radio galaxies to study the NIR stellar properties of
their host galaxies. As a homogeneous comparison sample, we used 9 inactive
elliptical galaxies that were observed with similar resolution and wavelength
range. The aim of the study is to compare the NIR spectral properties of radio
galaxies to those of inactive early-type galaxies and, furthermore, produce the
first NIR HK-band spectra for low redshift radio galaxies. For both samples
spectral indices of several diagnostic absorption features, SiI(1.589microns),
CO(1.619microns), NaI(2.207microns), CaI(2.263microns), CO(>2.29microns), were
measured. To characterize the age of the populations, the measured EWs of the
absorption features were fitted with the corresponding theoretical evolutionary
curves of the EWs calculated by the stellar synthesis model. On average, EW(CO
2.29) of radio galaxies is somewhat greater than that of inactive ellipticals.
Most likely, EW(CO 2.29) is not significantly affected by dilution, and thus
indicating that elliptical galaxies containing AGN are in a different stage in
their evolution than inactive ellipticals. This is also supported by comparing
other NIR features, such as CaI and NaI, with each other. Absorption features
are consistent with the intermediate age stellar population, suggesting that
host galaxies contain both an old and intermediate age components. It is
consistent with previous optical spectroscopy studies which have shown evidence
on the intermediate age (~2 Gyr) stellar population of radio galaxies, and also
in some of the early-type galaxies. The existence of intermediate age
population is a link between the star formation episode, possibly induced by
interaction or merging event, and the triggering of the nuclear activity.Comment: 10 pages, 7 figure
Impacts of winter feeding of reindeer on vegetation and soil in the sub-Arctic: insights from a feeding experiment
The overall impacts of winter feeding, including the effects of both forage and reindeer (Rangifer tarandus), were studied in an experiment in the Hammastunturi herding cooperative (68°N), Finland, with 300 reindeer in a sub-xeric heath forest (35 ha) during March/April 2009 and 2010. The feeding practices on the 50 plots were: (1) feeding with grass silage+hay with leftovers cleared in the spring; (2) feeding with grass silage+hay with leftovers not cleared; and (3) feeding with pellets. In addition, (4) unfenced and (5) fenced control plots were included, on which the reindeer were not fed. No invasive plant species introduced through grass silage+hay were observed on the plots. The coverage of Deschampsia flexuosa increased on grass silage+hay plots after the first winter, and both coverage and height of the grass increased after the second winter. The coverage of Dicranum sp. and Pleurozium schreberi was lower on plots where reindeer were fed with grass silage (leftover silage not cleared) vs. controls. Some dwarf shrubs, e.g., Calluna vulgaris, showed a similar response after the second winter. The N content of Empetrum nigrum was higher on grass silage plots (leftover silage not cleared) after the first winter vs. controls. After two winters, the N content of both E. nigrum and Vaccinium myrtillus was increased. Of the soil variables studied, C/N decreased on grass silage+hay plots vs. fenced controls. We conclude that even a moderate level of feeding may cause changes that can lead to a gradual shift from nutrient-poor heath forest towards a more nutrient-rich type
Mechanisms of polyamine catabolism-induced acute pancreatitis
Abstract Acute pancreatitis is an autodigestive disease, in which the pancreatic tissue is damaged by the digestive enzymes produced by the acinar cells. Among the tissues in the mammalian body, pancreas has the highest concentration of the natural polyamine, spermidine. We have found that pancreas is very sensitive to acute decreases in the concentrations of the higher polyamines, spermidine and spermine. Activation of polyamine catabolism in transgenic rats overexpressing SSAT (spermidine/spermine-N 1 -acetyltransferase) in the pancreas leads to rapid depletion of these polyamines and to acute necrotizing pancreatitis. Replacement of the natural polyamines with methylated polyamine analogues before the induction of acute pancreatitis prevents the development of the disease. As premature trypsinogen activation is a common, early event leading to tissue injury in acute pancreatitis in human and in experimental animal models, we studied its role in polyamine catabolism-induced pancreatitis. Cathepsin B, a lysosomal hydrolase mediating trypsinogen activation, was activated just 2 h after induction of SSAT. Pre-treatment of the rats with bismethylspermine prevented pancreatic cathepsin B activation. Analysis of tissue ultrastructure by transmission electron microscopy revealed early dilatation of rough endoplasmic reticulum, probable disturbance of zymogen packaging, appearance of autophagosomes and later disruption of intracellular membranes and organelles. Based on these results, we suggest that rapid eradication of polyamines from cellular structures leads to premature zymogen activation and autodigestion of acinar cells
Structure and tie strengths in mobile communication networks
Electronic databases, from phone to emails logs, currently provide detailed
records of human communication patterns, offering novel avenues to map and
explore the structure of social and communication networks. Here we examine the
communication patterns of millions of mobile phone users, allowing us to
simultaneously study the local and the global structure of a society-wide
communication network. We observe a coupling between interaction strengths and
the network's local structure, with the counterintuitive consequence that
social networks are robust to the removal of the strong ties, but fall apart
following a phase transition if the weak ties are removed. We show that this
coupling significantly slows the diffusion process, resulting in dynamic
trapping of information in communities, and find that when it comes to
information diffusion, weak and strong ties are both simultaneously
ineffective.Comment: 30 pages (manuscript + supplementary material), 11 figure
New approaches to model and study social networks
We describe and develop three recent novelties in network research which are
particularly useful for studying social systems. The first one concerns the
discovery of some basic dynamical laws that enable the emergence of the
fundamental features observed in social networks, namely the nontrivial
clustering properties, the existence of positive degree correlations and the
subdivision into communities. To reproduce all these features we describe a
simple model of mobile colliding agents, whose collisions define the
connections between the agents which are the nodes in the underlying network,
and develop some analytical considerations. The second point addresses the
particular feature of clustering and its relationship with global network
measures, namely with the distribution of the size of cycles in the network.
Since in social bipartite networks it is not possible to measure the clustering
from standard procedures, we propose an alternative clustering coefficient that
can be used to extract an improved normalized cycle distribution in any
network. Finally, the third point addresses dynamical processes occurring on
networks, namely when studying the propagation of information in them. In
particular, we focus on the particular features of gossip propagation which
impose some restrictions in the propagation rules. To this end we introduce a
quantity, the spread factor, which measures the average maximal fraction of
nearest neighbors which get in contact with the gossip, and find the striking
result that there is an optimal non-trivial number of friends for which the
spread factor is minimized, decreasing the danger of being gossiped.Comment: 16 Pages, 9 figure
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