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"Crabtree, Marc"
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FCC oks TivoToGo
The FCC gave the greenlight to sharing service TivoToGo, which will allow TiVo users to record and send programming to nine other TiVo boxes or computers via the Internet.
Magazine Article
Meet my neighbor, the dentist
David Meisels is a dentist. Meet his family and peek behind the curtain of a busy dental office.
BOOK
Ezh2, the histone methyltransferase of PRC2, regulates the balance between self-renewal and differentiation in the cerebral cortex
Multipotent progenitor cells of the cerebral cortex balance self-renewal and differentiation to produce complex neural lineages in a fixed temporal order in a cell-autonomous manner. We studied the role of the polycomb epigenetic system, a chromatin-based repressive mechanism, in controlling cortical progenitor cell self-renewal and differentiation. We found that the histone methyltransferase of polycomb repressive complex 2 (PCR2), enhancer of Zeste homolog 2 (Ezh2), is essential for controlling the rate at which development progresses within cortical progenitor cell lineages. Loss of function of Ezh2 removes the repressive mark of trimethylated histone H3 at lysine 27 (H3K27me3) in cortical progenitor cells and also prevents its establishment in postmitotic neurons. Removal of this repressive chromatin modification results in marked up-regulation in gene expression, the consequence of which is a shift in the balance between self-renewal and differentiation toward differentiation, both directly to neurons and indirectly via basal progenitor cell genesis. Although the temporal order of neurogenesis and gliogenesis are broadly conserved under these conditions, the timing of neurogenesis, the relative numbers of different cell types, and the switch to gliogenesis are all altered, narrowing the neurogenic period for progenitor cells and reducing their neuronal output. As a consequence, the timing of cortical development is altered significantly after loss of PRC2 function.
Journal Article
Developing Transdisciplinary Approaches to Sustainability Challenges: The Need to Model Socio-Environmental Systems in the Longue Durée
Human beings are an active component of every terrestrial ecosystem on Earth. Although our local impact on the evolution of these ecosystems has been undeniable and extensively documented, it remains unclear precisely how our activities are altering them, in part because ecosystems are dynamic systems structured by complex, non-linear feedback processes and cascading effects. We argue that it is only by studying human–environment interactions over timescales that greatly exceed the lifespan of any individual human (i.e., the deep past or longue durée), we can hope to fully understand such processes and their implications. In this article, we identify some of the key challenges faced in integrating long-term datasets with those of other areas of sustainability science, and suggest some useful ways forward. Specifically, we (a) highlight the potential of the historical sciences for sustainability science, (b) stress the need to integrate theoretical frameworks wherein humans are seen as inherently entangled with the environment, and (c) propose formal computational modelling as the ideal platform to overcome the challenges of transdisciplinary work across large, and multiple, geographical and temporal scales. Our goal is to provide a manifesto for an integrated scientific approach to the study of socio-ecological systems over the long term.
Journal Article
Developing Transdisciplinary Approaches to Sustainability Challenges: The Need to Model Socio-Environmental Systems in the ILongue Durée/I
Human beings are an active component of every terrestrial ecosystem on Earth. Although our local impact on the evolution of these ecosystems has been undeniable and extensively documented, it remains unclear precisely how our activities are altering them, in part because ecosystems are dynamic systems structured by complex, non-linear feedback processes and cascading effects. We argue that it is only by studying human–environment interactions over timescales that greatly exceed the lifespan of any individual human (i.e., the deep past or longue durée), we can hope to fully understand such processes and their implications. In this article, we identify some of the key challenges faced in integrating long-term datasets with those of other areas of sustainability science, and suggest some useful ways forward. Specifically, we (a) highlight the potential of the historical sciences for sustainability science, (b) stress the need to integrate theoretical frameworks wherein humans are seen as inherently entangled with the environment, and (c) propose formal computational modelling as the ideal platform to overcome the challenges of transdisciplinary work across large, and multiple, geographical and temporal scales. Our goal is to provide a manifesto for an integrated scientific approach to the study of socio-ecological systems over the long term.
Journal Article
A Method to Estimate the Depth of the Sciatic Nerve During Subgluteal Block by Using Thigh Diameter as a Guide
The subgluteal approach is common for sciatic nerve block. Although the surface landmarks are clear, the depth of this nerve at this level is difficult to judge. The purpose of this study is to establish a method of estimating the sciatic nerve depth using the anteroposterior (AP) diameter of the thigh as a marker.
The study was undertaken in 2 phases. Phase 1 entailed review of 100 magnetic resonance images (MRIs) of the pelvis and proximal lower extremity of patients. Measurements were taken of the AP diameter of the thigh at the midpoint of the lesser trochanter and then compared with distances of the sciatic nerves from the skin of the posterior aspect of the thigh at the same level. Phase 2 involved enrolling 40 patients undergoing lower-extremity surgery for whom subgluteal sciatic nerve blocks were indicated. The AP diameters of the thighs were measured from the subgluteal groove to the inguinal groove with the patient in the supine position. Placing the patient in the lateral position, the subgluteal sciatic block was then performed by using a stimulating needle. The distances from the skin at which the sciatic nerves were actually found, as estimated by maximum motor response to stimulus, were noted.
Phase 1 showed a mean AP diameter of 18.94 cm ± 2.61 cm (mean ± standard deviation [SD]), mean nerve depth of 6.51 cm ± 1.46 cm (mean ± SD), and a linear regression slope of 0.48. Phase 2 showed a mean AP diameter of 16.28 cm ± 2.73cm (mean ± SD), a mean nerve depth of 6.99 cm ± 1.39 cm (mean ± SD), and a linear regression slope of 0.43. The thigh diameters differed (
P < .001) between the groups, but there was no difference in the depth to the sciatic nerve between the 2 groups (
P = .07).
Comparing phase 1 and phase 2 datasets shows the slopes of linear regression lines are nearly parallel. The clinical data from phase 2 verify the anatomical data collected in phase 1 and show that the sciatic nerve depth to AP diameter ratio is 0.43 or the depth of the sciatic nerve is approximately 43% of thigh diameter if the patient is positioned in the lateral decubitus position.
Journal Article