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Core contributions from John Hagan’s scholarship on genocide are at stake in this article. First, this article examines, for the Rwandan genocide, the applicability of Hagan and Wenona Rymond-Richmond’s multi-level causal model of genocide, developed in Darfur and the Crime of Genocide. Asking how causal factors and processes highlighted in that model play out in scholarship on the Rwandan genocide, it moves toward answering the question of external validity versus historical specificity. Second, the article examines, again with a focus on Rwanda, the relationship between social scientific explanation and judicial thought. While it highlights—in line with the first author’s previous work—how judicial narratives address or select out core factors highlighted in the Darfur model, the article focuses—in line with Hagan’s Justice in the Balkans—on the question of what knowledge social science can nevertheless gain from court proceedings. An analysis of a sample of cases processed by the International Criminal Tribunal for Rwanda identifies overlaps with social science analyses, but it also highlights distinctions.
In this work a combined analysis of the out-of-plane mechanical and the electromagnetic properties of auxetic re-entrant honeycombs is performed. Experimental and numerical simulations are carried out to evaluate the correlation between the anisotropicity of the transverse mechanical properties (shear and compressive modulus) and the permittivity tensor of auxetic honeycombs. The results are evaluated to assess the feasibility of this kind of cellular solid for electromagnetic absorption and window applications with high structural integrity performance.
Educators are advocating a variety of 21st century technologies to increase student engagement and prepare them for the modern workplace. As part of this effort this paper describes the development of several introductory laboratory activities which enhance online collaborative skills in the context of group collaborations. The experiments mostly deal with measurement and error in the context of mathematical modeling. They inculcate online collaborative skills including group writing, collection of experimental data, student feedback, and assessment using forms, spreadsheets with data pooling, real-time graphing/computations, and discussions using chat. These are all available in Google Drive, a free cloudbased application. We have also introduced student collaborative-pair computational spreadsheet assignments, and results of two projects in general chemistry are presented. Building formative assessment into these activities allows for immediate adjustment to instruction. This approach could be used from middle school through the undergraduate level. It can be implemented both in informal education or formal classroom settings by enhancing interactions with remote partners. Student evaluations have been very positive for the variety of activities, as well as from workshop feedback from high school teachers.
Linked administrative population data were used to estimate the burden of childhood respiratory syncytial virus (RSV) hospitalization in an Australian cohort aged <5 years. RSV-coded hospitalizations data were extracted for all children aged <5 years born in New South Wales (NSW), Australia between 2001 and 2010. Incidence was calculated as the total number of new episodes of RSV hospitalization divided by the child-years at risk. Mean cost per episode of RSV hospitalization was estimated using public hospital cost weights. The cohort comprised of 870 314 children. The population-based incidence/1000 child-years of RSV hospitalization for children aged <5 years was 4·9 with a rate of 25·6 in children aged <3 months. The incidence of RSV hospitalization (per 1000 child-years) was 11·0 for Indigenous children, 81·5 for children with bronchopulmonary dysplasia (BPD), 10·2 for preterm children with gestational age (GA) 32–36 weeks, 27·0 for children with GA 28–31 weeks, 39·0 for children with GA <28 weeks and 6·7 for term children with low birthweight. RSV hospitalization was associated with an average annual cost of more than AUD 9 million in NSW. RSV was associated with a substantial burden of childhood hospitalization specifically in children aged <3 months and in Indigenous children and children born preterm or with BPD.
Oligodendrogliomas respond to nitrosourea-based chemotherapy and are induced in rats following transplacental exposure to ethylnitrosourea, observations suggesting that neoplastic and normal cells of the oligodendrocyte lineage are “sensitive” to nitrosoureas. Nitrosoureas alkylate DNA at O6-guanine with repair mediated by O6-methyIguanine-DNA methyltransferase (MGMT). The cytotoxic and carcinogenic properties of the nitrosoureas appear related to MGMT activity.
Methods:
To explore why oligodendrogliomas respond to chemotherapy, we measured MGMT activity in five chemosensitive human oligodendrogliomas and in rat oligodendrocyte lineage cells. We also measured MGMT activity in rat astrocytes and compared the cytotoxic effects of carmustine (BCNU) on oligodendrocyte lineage cells and astrocytes.
Results:
Low levels of MGMT activity were found in five of five human oligodendrogliomas. Cultures of neonatal rat glia enriched for oligodendrocyte lineage cells also had low levels of MGMT activity, approximately one-third that found in astrocytes (p < 0.02), and oligodendrocyte lineage cells were more sensitive to BCNU than astrocytes.
Conclusions:
Low MGMT activity may contribute to the chemosensitivity of some human oligodendrogliomas and rat oligodendrocyte lineage cells also have low levels. If drug resistance mechanisms in tumors reflect the biochemical properties of their cells of origin, then normal glia may serve as a laboratory substitute for human glioma.
The Wilkes Land Gravity Anomaly, first reported in 1959–60, is located in northern Victoria Land in the Pacific Ocean sector of East Antarctica, 1400 km west of the Ross Sea and centred at 70°00'S-140°00'E. Initially described on the basis of ground-based seismic and gravity survey, and estimated at the time to have a diameter of 243 km, the original data are now supplemented by data from airborne radiosound survey, airborne gravity survey, airborne magnetic survey and satellite remote sensing. These new data enable us to expand upon the original data, and reveal that the structure has a diameter of some 510 km, is accompanied by ice streams and a chaotically disturbed region of the continental ice sheet, has a subglacial topographical relief of ≥1500 m, and exhibits a negative free air gravity anomaly associated with a larger central positive free air gravity anomaly. The feature has been described as a volcanic structure, an igneous intrusion, an ancient igneous diapir, a subglacial sedimentary basin, a glacially eroded subglacial valley, a tectonic feature and a meteorite impact crater. We re-examine the feature on the basis of these collective data, with emphasis on the free air gravity anomaly signs, magnitudes and patterns, magnetic signature magnitudes and patterns, and the size, shape, dimensions and morphology of the structure. This enhanced view adds substantially to the original description provided at the time of discovery, and suggests several explanations for the origin of the Wilkes Land Anomaly. However, the importance of this feature lies not only in determining its origin but by the fact that this part of the Wilkes Subglacial Basin is one of the most prominent regional negative geoid and associated gravity anomalies of the Antarctic continent.
The Next Generation Science Standards make scientific discourse a vital part of the classroom and arguing with evidence needs to become a common practice for students. Analysis and interpretation of data are an integral part as well. We present an approach using 21st-century technology combined with collection of laboratory data that is suitable for middle school through college. In an experiment using common nuts and bolts first semester chemistry students form six groups and determine a bolt mass indirectly. They collect mass data; then enter the data into an online form that compiles the data into a spreadsheet in Google Drive, a free cloud-based application. Once all the groups have submitted their data, they access the spreadsheet online and start an emulated online discussion in the laboratory as if the groups were globally dispersed using the chat feature available in Google Drive. Each group is identified by a group number having a unique group email address so there is a semi-anonymous sense among the members that allows for a fairly free discussion among students.
The Wilkes Subglacial Basin (WSB), the largest subglacial basin in East Antarctica, is a topographic depression of continental proportions that lies beneath the East Antarctic continental ice sheet. Discovered by the US Victoria Land Traverse 1959–60, the origin of the WSB and the influence of palaeoclimate on its overlying continental ice sheet have remained uncertain since the time of its discovery. Most explanations of origin favour lithospheric structural control as a function of tectonic activity. Lithospheric flexure due to thermally or isostatically induced uplift of the Transantarctic Mountains was suggested in the 1980s. Lithospheric extension and rifting was proposed in the 1990s. More recent investigations have revealed the presence of fold and thrust belts, casting doubt on flexural and extensional hypotheses as the primary mechanisms, suggesting instead a compressional scenario. While remaining inconclusive, these tectonic mechanisms in one form or another, or in combination, are now believed to have provided the structural control for the origin of the WSB. Not yet comprehensively examined, however, is the role of non-tectonic processes in the formation of the WSB, as they may have influenced the size, configuration, subglacial sedimentation and subglacial topography of the WSB. In this paper we review the tectonic hypotheses and examine post-tectonic climate change along with glacial and marine processes as potentially significant factors in the present condition and configuration of the WSB. In the process, we find that there are a number of features not included in previous investigations that may have been major factors in the modification of the subglacial basin.
High-redshift quasars are unique probes of the evolution of supermassive black holes and the intergalactic medium at the end of the epoch of reionization. We present the optical spectra of eight new z ~ 6 quasars selected from the Panoramic Survey Telescope & Rapid Response System 1 (Pan-STARRS1). Details of the selection strategy can be found in Bañados et al. (2014). With this work we increase the number of known quasars at z < 5.7 by more than 10%. The quasars discovered here span a large range of luminosities (19.6 ≤ zP1 ≤ 21.2) and are remarkably heterogeneous in their spectral features: half of them show bright emission lines whereas the other half show weak or no Lyα emission line. We find a larger fraction of weak–line emission quasars than in lower redshift studies, although still based on low number statistics, this may imply that the quasar population could be more diverse than previously thought.
Local food systems are comprised of networks of actors that work to ensure the sustainability of food supplies within communities. While local food has typically been promoted through direct marketing strategies such as farmers' markets and community-supported agriculture (CSA), retail stores are increasingly carrying and marketing local foods in response to consumer demand and market potential. Given the frequency with which consumers shop at grocery stores, as well as the portion of consumers' food purchases made at these locations, these stores may play a significant role in the success of local agriculture and the shaping of ideology about what is ‘local’. We conducted 27 semi-structured interviews with representatives of food retailers known to source and market local foods in the four major urban centers of Oregon's Willamette Valley. Our results reveal that grocers' perceptions of local food vary significantly from one another. Additionally, our results differed in comparison to the published literature on consumers' and producers' ideas of what constitutes local. Food retailers identified varying distances (frequently a region including several states) that they consider local, as well as diverse reasons for choosing to source and market local foods (most commonly supporting the local economy). Some trends in the variation of responses relate to how the size and form of ownership of the grocery stores influence the level at which decisions are made. These wide-ranging perceptions outline many of the realities of the local food movement, as well as opportunities for change.
Transesophageal echocardiography (TEE) is a useful modality for imaging cardiac masses. Atrial myxomas account for 90% of all cardiac tumors found at operation, and 50% of tumors found at autopsy. Pericardial cysts are frequently asymptomatic and may be an incidental finding. Mediastinal cysts, including bronchogenic and duplication cysts, may occur. These have a more echodense appearance on TEE, and may contain thicker mucilaginous material that may layer differently with postural change. Cardiac tamponade may be defined as the decompensated phase of cardiac compression resulting from increased intrapericardial pressure. Constrictive pericarditis is characterized by a fibrotic, inflamed, or calcified pericardial sac. In patients with a suspected cardiac mass, transesophageal echocardiography is recommended for determining its nature, and the assessment of sources of cardiac embolism. It may be particularly useful in patients with loculated or trapped pericardial fluid, for example in the post-operative setting.
The recognition that postcumulus processes significantly modify primary textures in layered mafic intrusions has thrown into question many early observations on which classical crystallization theories are based. Petrographic observations combined with quantitative textural analysis of samples from various stratigraphic levels of the Lilloise intrusion, East Greenland, demonstrate that postcumulus textural modification of cumulates, formed during the solidification of a closed system magma chamber, may be detected. Crystal size distribution (CSD) measurements of Lilloise cumulates and the resulting CSD profiles are compared to predicted theoretical closed system CSD profiles. Similarities between the measured CSD profiles and published predicted CSD profiles support Lilloise magma evolving in a closed system chamber and indicate that primary crystallization processes can be distinguished using quantitative textural techniques. Textural coarsening driven by syn-magmatic deformation is suggested to be the dominant postcumulus process affecting CSD plot morphology. CSD slope values and profiles (plot shapes) remain relatively constant for a given liquidus mineral (particularly olivine and clinopyroxene), so that the number of phases on the liquidus at any one time affects mineral modal abundances. As a result, CSDs generally exhibit overall smaller grainsizes and progressively lower nucleation densities at higher levels in the intrusion.
The Pan-STARRS 1 Telescope (PS1) is currently (2009 Aug) undergoing final commissioning efforts and starting to perform initial science observations for the PS1 survey mission. PS1 will greatly expand the known population of Brown Dwarfs, with discovery via photometry, proper-motion, and parallax.
We investigated the possibility of doping poly (sodium poly[2-(3-thienyl)-ethoxy-4-butylsulfonate) (PTEBS) with perylene tetracarboxylicdiimide (PTCDI) nanobelts through ultraviolet photoelectron spectroscopy (UPS) measurements. For our experiment, PTEBS was tuned to absorb maximum light in the range of 450 nm to 550 nm which corresponds to the maximum solar irradiance of the Earth’s atmosphere. Nanobelts of PTCDI were synthesized by gas phase self assembly process. Doping PTEBS with PTCDI nanobelts causes a shift in the Fermi level of the composite material with respect to the vacuum level as observed in the photoemission spectrum. With increased PTCDI doping, PTCDI does not act much like an electron donor, but more like an electron acceptor. The peaks corresponding to the sigma bonds shift towards the vacuum level with higher concentrations of the dopant. Using angled resolved photoemission spectra from a 3m toroidal grating monochromator, PTEBS displays change in the highest occupied molecular orbital in respect to its Fermi level when the side groups were substituted by H+ or OH- groups. The results confirm that the binding energy decreases with increase in activity of the dissolved hydrogen ions. It is evident that there is an increase in the density of states near the Fermi level and shifts to lower binding energies of the occupied molecular orbitals with pH level decrease, which is in agreement with the published optical absorption characteristics of PTEBS. Since UPS data confirm that PTCDI nanobelts dope PTEBS, along with its tunable absorption characteristics, this composite might be a promising material for optoelectronic application.
Most stars are formed in a cluster or association, where the number density of stars can be high. This means that a large fraction of initially-single stars will undergo close encounters with other stars and/or exchange into binaries. We describe how such close encounters and exchange encounters can affect the properties of a planetary system around a single star. We define a singleton as a single star which has never suffered close encounters with other stars or spent time within a binary system. It may be that planetary systems similar to our own solar system can only survive around singletons. Close encounters or the presence of a stellar companion will perturb the planetary system, often leaving planets on tighter and more eccentric orbits. Thus planetary systems which initially resembled our own solar system may later more closely resemble some of the observed exoplanet systems.
In the self-preserving region of a slightly heated turbulent plane jet, conventional isocorrelation contours of velocity and temperature fluctuations support the existence of organized large-scale structures. Temperature fronts associated with these structures were visually detected using a spanwise rake of cold wires. This method of detection was then used to condition velocity and temperature fluctuations and products of these fluctuations. Ensemble-averaged velocity vectors, constructed in the plane of main shear, suggest a topology for the organized motion in which the temperature front is identified with the diverging separatrix connecting adjacent structures on the same side of the centreline. Coherent stresses and heat fluxes are particularly significant near the diverging separatrix. Contributions by the coherent and random motions to the averaged momentum and heat transports are generally of the same order of magnitude.