Strategies for Improving Semi-automated Topic Classification of Media and Parliamentary documents

Since 1995 the techniques and capacities to store new electronic data and to make it available to many persons have become a common good. As of then, different organizations, such as research institutes, universities, libraries, and private companies (Google) started to scan older documents and make them electronically available as well. This has generated a lot of new research opportunities for all kinds of academic disciplines. The use of software to analyze large datasets has become an important part of doing research in the social sciences. Most academics rely on human coded datasets, both in qualitative and quantitative research. However, with the increasing amount of datasets and the complexity of the questions scholars pose to the datasets, the quest for more efficient and effective methods is now on the agenda. One of the most common techniques of content analysis is the Boolean key-word search method. To find certain topics in a dataset, the researcher creates first a list of keywords, added with certain parameters (AND, OR etc.). All keys are usually grouped in families and the entire list of keys and groups is called the ontology. Then the keywords are searched in the dataset, retrieving all documents containing the specified keywords. The online newspaper dataset, LexisNexis, provides the user with such a Boolean search method. However, the Boolean key-word search is not always satisfying in terms of reliability and validity. For that reason social scientists rely on hand-coding. Two projects that do so are the congressional bills project (www.congressionalbills.org ) and the policy agenda-setting project (see www.policyagendas.org ). They developed a topic code book and coded various different sources, such as, the state of the union speeches, bills, newspaper articles etcetera. The continuous improving automated coding techniques, and the increasing number of agenda setting projects (in especially European countries), however, has made the use of automated coding software a feasible option and also a necessity

The timing of gold mineralization in White Bay, western Newfoundland: Evidence from 40Ar/39Ar studies of mafic dykes that predate and postdate mineralization

The Rattling Brook deposit is a low-grade, disseminated to stockwork-style gold deposit hosted by Precambrian granodiorite and adjacent Cambrian sedimentary rocks. Alteration and gold mineralization also occur in foliated and metamorphosed mafic dykes, likely of late Precambrian age. The auriferous granodiorite is in turn cut by relatively fresh, unaltered, and locally chilled diabase dykes, interpreted as Paleozoic post-mineralization intrusions. A fresh post-mineralization diabase gave a 40Ar/39Ar amphibole plateau age of 412.9 ± 4.3 Ma, which is interpreted as the time of its crystallization, and which provides a younger limit for the timing of gold mineralization. An altered, metamorphosed dyke of pre-mineralization timing gave an identical 40Ar/39Ar biotite plateau age of 412.6 ± 2.3 Ma, which is more difficult to interpret. It could represent post-metamorphic cooling, or alternatively, resetting of metamorphic biotite during alteration related to gold mineralization. In the first case, the age provides a reasonable upper limit for the timing of gold mineralization, provided that the ambient temperature during mineralization was not significantly above the closure temperature for Ar in biotite (~ 300 oC). On this basis, gold mineralization at Rattling Brook occurred during the latest Silurian or earliest Devonian, between 415 and 409 Ma. The possibility that mineralization occurred at temperatures above 300 oC, prior to 415 Ma, cannot be completely excluded, but it must be younger than ca. 430 Ma, the time of peak metamorphism in adjacent areas. In conjunction with sparse data on the ages of gold deposits elsewhere in Newfoundland, the results support two discrete episodes of mineralization corresponding to the Silurian-Devonian boundary (420–410 Ma) and middle to late Devonian (380–370 Ma). These age groupings resemble those defined by recent Re-Os isotopic studies of sulphides from vein-style gold deposits in the Meguma terrane of Nova Scotia and may in part correspond to the timing of intrusion-related gold in New Brunswick. Given the small amount of data from all of these areas, further interpretation is speculative. However, such hints of discrete orogen-scale episodes of gold mineralization, perhaps correlative with regional tectonothermal events, provide a powerful incentive for further geochronological studies of gold mineralization in the Appalachian orogen. Résumé Le gîte du ruisseau Rattling est un gîte aurifère à faible teneur qui, de disséminé, devient un stockwerk inclus dans de la granodiorite précambrienne et des roches sédimentaires cambriennes adjacentes. Une altération et une minéralisation aurifère se manifestent également dans des dykes mafiques métamorphisés et feuilletés, remontant probablement au Précambrien tardif. La granodiorite aurifère est à son tour recoupée par des dykes de diabase figés par endroits, non altérés et relativement sains, interprétés en tant qu’intrusions paléozoïques ultérieures à la minéralisation. Une diabase post-minéralisation inaltérée a accusé un âge plateau sur amphibole 40Ar/39Ar de 412,9 ± 4,3 Ma, ce qui est interprété comme le moment de sa cristallisation et rapproche la limite du moment de la minéralisation aurifère. Un dyke métamorphisé altéré, antérieur à la minéralisation, a livré un âge plateau sur biotite 40Ar/39Ar identique de 412,6 ± 2,3 Ma, qui est plus difficile à interpréter. Celui-ci pourrait représenter un refroidissement post-métamorphique ou, subsidiairement, une remise en place de la biotite métamorphique au cours de l’altération apparentée à la minéralisation aurifère. Dans le premier cas, la datation fournit une limite supérieure raisonnable quant au moment de la minéralisation aurifère, à condition que la température ambiante pendant la minéralisation n’ait pas été substantiellement supérieure à la température de convergence de l’AR dans la biotite (environ 300 oC). Le cas échéant, la minéralisation d’or du ruisseau Rattling est survenue au cours du Silurien tardif ou du Dévonien précoce, entre 415 et 409 Ma. La possibilité que la minéralisation se soit produite à des températures supérieures à 300 oC, avant 415 Ma, ne peut pas être entièrement exclue, mais la minéralisation doit être antérieure à 430 Ma environ, point culminant du métamorphisme dans les secteurs voisins. Outre les rares données sur les âges des gîtes d’or ailleurs à Terre-Neuve, les résultats appuient la manifestation de deux épisodes distincts de minéralisation correspondant à la limite siluro-dévonienne (420–410 Ma) et à la période du Dévonien moyen à tardif (380–370 Ma). Ces groupes d’âges ressemblent à ceux définis lors de récentes études isotopiques Re-Os de sulfures provenant de gîtes aurifères filoniens dans le terrane de Meguma en Nouvelle-Écosse et ils pourraient en partie correspondre au moment de l’apparition de l’or lié à une intrusion au Nouveau-Brunswick. Vu la somme restreinte de données tirées de l’ensemble de ces secteurs, effectuer une interprétation plus détaillée serait se livrer à des conjectures. Les indices comme les épisodes distincts de minéralisation aurifère à l’échelle orogénique, qui pourraient être corrélatifs avec des événements tectonothermiques régionaux, fournissent toutefois un puissant incitatif pour réaliser des études chronologiques plus poussées de la minéralisation aurifère dans l’orogène des Appalaches

Androgen-regulated gastrin-releasing peptide receptor expression in androgen-dependent human prostate tumor xenografts

Human prostate cancer (PC) overexpresses the gastrin-releasing peptide receptor (GRPR). Radiolabeled GRPR-targeting analogs of bombesin (BN) have successfully been introduced as potential tracers for visualization and treatment of GRPR-overe

Bioerosion and sediment ingestion by the Caribbean parrotfish Scarus vetula and Sparisoma viride:Implications of fish size, feeding mode and habitat use

Erosion rates and sources of sediment ingested were quantified for the 2 most abundant parrotfish species on a leeward fringing reef of Bonaire, Netherlands Antilles: Scarus vetula and Sparisoma viride. Direct estimates of erosion by different size classes were obtained from daily feeding rates and grazing scar frequency, scar volume and substrate density. Foraging preference and distribution of fish on the reef were used to examine patterns of bioerosion at 2 spatial scales: reef zones and individual substrates used for grazing. Sediment mass ingested by fish provided an independent check on erosion rates, and was partitioned according to source. S. vetula, employing a scraping feeding mode, removed less material from grazed substrates than similar sized S. viride, which forages by excavating the substrate. Erosion rates increased strongly with fish size in both species. The (indigestible) carbonate derived from epilithic algae accounted for all sediment ingested by juvenile fish. In adult fish, the proportion of freshly eroded carbonate substrate ingested increased with fish size. The distribution of adults of these large scarids over different reef zones determines the rate of bioerosion on a large spatial scale. The highest bioerosional rates occur on the shallow reef (ca 7 kg m(-2) yr(-1)), and they decrease with depth. Parrotfish foraging preferences, and the effects of food type and skeletal density of substrates on the size of the grazing scars, cause large differences in bioerosional rates on a small spatial scale. The highest rates of bioerosion occur on substrates infested with boring algae and of low skeletal density, while high-density substrates and substrates covered with crustose corallines undergo lower rates. Living coral is rarely eaten by scarids, and largely escapes erosion by grazing

Nothing moves a surface: vacancy mediated surface diffusion

We report scanning tunneling microscopy observations, which imply that all atoms in a close-packed copper surface move frequently, even at room temperature. Using a low density of embedded indium `tracer' atoms, we visualize the diffusive motion of surface atoms. Surprisingly, the indium atoms seem to make concerted, long jumps. Responsible for this motion is an ultra-low density of surface vacancies, diffusing rapidly within the surface. This interpretation is supported by a detailed analysis of the displacement distribution of the indium atoms, which reveals a shape characteristic for the vacancy mediated diffusion mechanism that we propose.Comment: 4 pages; for associated movie, see http://www-lion.leidenuniv.nl/sections/cm/groups/interface/projects/therm

Zorgvuldig vertrouwen!

Politieke besluitvorming over intensieve veehouderij is regelmatig onderwerp van heftige discussies. Aan de orde zijn vele en onderling conflicterende waarden, opvattingen en feiten. Dit essay analyseert een besluitvormingsproces over de vestiging van een megastal. Tijdens dit proces bleken de verschillende belevingswerelden van boeren, burgers, politici en wetenschappers te botsen