Global Oceans Johnson, Gregory C.; Lumpkin, Rick; Boyer, Tim ...
Bulletin of the American Meteorological Society,
08/2022, Letnik:
103, Številka:
8
Journal Article
We report the first in vivo cardiac magnetic resonance imaging (MRI) measurements of Theraphosidae spiders. MRI scanning is performed on six spiders under isoflurane‐induced anaesthesia. ...Retrospective self‐gating cine‐cardiac MRI (RG‐CINE‐MRI) is used to overcome the difficulties of prospective cardiac gating in this species. The resulting RG‐CINE‐MRI images are successfully analyzed to obtain functional cardiac parameters from live spiders at rest. Cardiac ejection fraction is found to increase with animal mass (Pearson correlation 0.849, P = 0.03) at a faster rate than myocardial tissue volume, whereas heart rate remains constant across animals. This suggests the spider heart undergoes additional biomechanical loading with age. The results of the present study demonstrate the potential for retrospective gating with respect to evaluating aspects of cardiac function in a wide range of previously inaccessible species.
We report the first in vivo invertebrate cardiac magnetic resonance imaging (MRI) measurements of Theraphosidae spiders, using retrospectively gated cine‐cardiac MRI.
A quantitative evaluation of cardiac functional parameters for Theraphosidae spiders is performed, with a correlation being found between the body mass of the spider and cardiac ejection fraction.
With increasing animal mass, cardiac ejection is found to increase at a faster rate than myocardial tissue volume, whereas heart rate stays constant. Suggesting additional biomechanical loading of the spider heart with age.
Abstract White matter (WM) abnormalities, possibly resulting from hypoperfusion, are key features of the aging human brain. It is unclear, however, whether in vivo magnetic resonance imaging (MRI) ...approaches, such as diffusion tensor and magnetization transfer MRI are sufficiently sensitive to detect subtle alterations to WM integrity in mouse models developed to study the aging brain. We therefore investigated the use of diffusion tensor and magnetization transfer MRI to measure structural changes in 4 WM tracts following 1 month of moderate hypoperfusion, which results in diffuse WM pathology in C57Bl/6J mice. Following MRI, brains were processed for evaluation of white and gray matter pathology. Significant reductions in fractional anisotropy were observed in the corpus callosum ( p = 0.001) and internal capsule ( p = 0.016), and significant decreases in magnetization transfer ratio were observed in the corpus callosum ( p = 0.023), fimbria ( p = 0.032), internal capsule ( p = 0.046) and optic tract ( p = 0.047) following hypoperfusion. Hypoperfused mice demonstrated diffuse axonal and myelin pathology which was essentially absent in control mice. Both fractional anisotropy and magnetization transfer ratio correlate with markers of myelin integrity/degradation and not axonal pathology. The study demonstrates that in vivo MRI is a sensitive measure of diffuse, subtle WM changes in the murine brain.
There is widespread concern about differences in the quality of state-run and private schooling. The concerns are especially severe in the numerous developing countries where much of the population ...has left state-provided schooling for private schooling, including many private schools not recognized by the government. The fees charged by the private schools serving the poor are quite low and they seem to yield better results, but many analysts dispute and insist that private sector quality is unacceptable, and that the only route to universal access to quality schooling is increased investment in state-run provision. Because those claims and counterclaims have seen little scientifically rigorous evidence to support them, this article analyzes data from schools serving the very poor in randomly selected schools in Lagos, Nigeria; Delhi, India; and Hyderabad, India to compare the performance of unrecognized private schools, state-recognized private schools, and zero-tuition, state-run schools. The authors' econometric analysis, which controls for socioeconomic factors and selection bias, shows that children enrolled in private schools significantly outperform children enrolled in the state-run schools despite much greater teacher salary expenditures in the latter. The recognized schools do not consistently fare better than the unrecognized schools. Given those results, and chronic frustration with efforts to improve state-run schools, reform advocates should consider shifting their focus to improvement of private schools, and expand access to them.
Marxism and Urban Culture is the first volume to reconcile social science and humanities perspectives on culture. Covering a range of global cities—Bologna, Buenos Aires, Guatemala City, Liverpool, ...London, Los Angeles, Madrid, Mahalla al-Kubra, Mexico City, Montreal, Osaka, Strasbourg, Vienna—the contributions fuse political and theoretical concerns with analyses of urban cultural practices and historical movements, as well as urban-themed literary and filmic art. Conceived as a response to the persistent rift between disciplinary Marxist approaches to culture, this book prioritizes the urban problematic and builds implicitly and explicitly on work by numerous thinkers: not only Karl Marx but also David Harvey, Henri Lefebvre, Friedrich Engels and Antonio Gramsci, among others. Rather than reanimate reductive views either of Marx or of urban theory, the chapters in Marxism and Urban Culture speak broadly to the interdisciplinary connections that are increasingly the concern of cultural scholars working across and beyond the boundaries of geography, sociology, history, political science, language and literature fields, film studies, and more. A foreword written by Andy Merrifield (the author of Metromarxism) and an introduction by Benjamin Fraser (the author of Henri Lefebvre and the Spanish Urban Experience) situate the book’s chapters firmly in interdisciplinary terrain.
Abstract
We report the first
in vivo
cardiac magnetic resonance imaging (MRI) measurements of Theraphosidae spiders. MRI scanning is performed on six spiders under isoflurane‐induced anaesthesia. ...Retrospective self‐gating cine‐cardiac MRI (RG‐CINE‐MRI) is used to overcome the difficulties of prospective cardiac gating in this species. The resulting RG‐CINE‐MRI images are successfully analyzed to obtain functional cardiac parameters from live spiders at rest. Cardiac ejection fraction is found to increase with animal mass (Pearson correlation 0.849,
P
= 0.03) at a faster rate than myocardial tissue volume, whereas heart rate remains constant across animals. This suggests the spider heart undergoes additional biomechanical loading with age. The results of the present study demonstrate the potential for retrospective gating with respect to evaluating aspects of cardiac function in a wide range of previously inaccessible species.
Abstract Increasing scientific interest in the zebrafish as a model organism across a range of biomedical and biological research areas raises the need for the development of in vivo imaging tools ...appropriate to this subject. Development of the embryonic and early stage forms of the subject can currently be assessed using optical based techniques due to the transparent nature of the species at these early stages. However this is not an option during the juvenile and adult stages when the subjects become opaque. Magnetic Resonance Imaging (MRI) techniques would allow for the longitudinal and non-invasive assessment of development and health in these later life stages. However, the small size of the zebrafish and its aquatic environment represent considerable challenges for the technique. We have developed a suitable flow cell system that incorporates a dedicated MRI imaging coil to solve these challenges. The system maintains and monitors a zebrafish during a scan and allows for it to be fully recovered. The imaging properties of this system compare well with those of other preclinical MRI coils used in rodent models. This enables the rapid acquisition of MRI data which is comparable in terms of quality and acquisition time. This would allow the many unique opportunities of the zebrafish as a model organism to be combined with the benefits of non-invasive MRI.
Global Oceans Johnson, G. C; Lumpkin, R; Atkinson, C ...
Bulletin of the American Meteorological Society,
09/2023, Letnik:
104, Številka:
9
Journal Article
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