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991.
992.
François Courchesne Marie-Claude Turmel Benoît Cloutier-Hurteau Gilbert Tremblay Lara Munro Jacynthe Masse 《International journal of phytoremediation》2017,19(7):632-642
This study determined the changes in trace elements (TE) (As, Cd, Cu, Ni, Pb, Zn) chemistry in the soils of a willow (“Fish Creek” – Salix purpurea, SV1 – Salix x dasyclados and SX67 – Salix miyabeana) plantation growing under a cold climate during a three-year trial. The soil HNO3-extractable and H2O-soluble TE concentrations and pools significantly decreased under most cultivars (Fish, SX67). Yet, TE changes showed inconsistent patterns and localized soil TE increases (Ni, Pb) were measured. Temporal changes in soil TE were also detected in control plots and sometimes exceeded changes in planted plots. Discrepancies existed between the amount of soil TE change and the amount of TE uptake by willows, except for Cd and Zn. Phytoremediation with willows could reduce soil Cd and Zn within a decadal timeframe indicating that they can be remediated by willows in moderately contaminated soils. However, the time needed to reduce soil As, Cu, Ni and Pb was too long to be efficient. We submit that soil leaching contributed to the TE decrease in controls and the TE discrepancies, and that the plantation could have secondary effects such as the accelerated leaching of soil TE. 相似文献
993.
Because electrical coupling among the neurons of the brain is much faster than chemical synaptic coupling, it is natural to
hypothesize that gap junctions may play a crucial role in mechanisms underlying very fast oscillations (VFOs), i.e., oscillations
at more than 80 Hz. There is now a substantial body of experimental and modeling literature supporting this hypothesis. A
series of modeling papers, starting with work by Roger Traub and collaborators, have suggested that VFOs may arise from expanding
waves propagating through an “axonal plexus”, a large random network of electrically coupled axons. Traub et al. also proposed
a cellular automaton (CA) model to study the mechanisms of VFOs in the axonal plexus. In this model, the expanding waves take
the appearance of topologically circular “target patterns”. Random external stimuli initiate each wave. We therefore call
this kind of VFO “externally driven”. Using a computational model, we show that an axonal plexus can also exhibit a second,
distinctly different kind of VFO in a wide parameter range. These VFOs arise from activity propagating around cycles in the
network. Once triggered, they persist without any source of excitation. With idealized, regular connectivity, they take the
appearance of spiral waves. We call these VFOs “re-entrant”. The behavior of the axonal plexus depends on the reliability
with which action potentials propagate from one axon to the next, which, in turn, depends on the somatic membrane potential
V
s
and the gap junction conductance g
gj
. To study these dependencies, we impose a fixed value of V
s
, then study the effects of varying V
s
and g
gj
. Not surprisingly, propagation becomes more reliable with rising V
s
and g
gj
. Externally driven VFOs occur when V
s
and g
gj
are so high that propagation never fails. For lower V
s
or g
gj
, propagation is nearly reliable, but fails in rare circumstances. Surprisingly, the parameter regime where this occurs is
fairly large. Even a single propagation failure can trigger re-entrant VFOs in this regime. Lowering V
s
and g
gj
further, one finds a third parameter regime in which propagation is unreliable, and no VFOs arise. We analyze these three
parameter regimes by means of computations using model networks adapted from Traub et al., as well as much smaller model networks. 相似文献
994.
R. Munro Ford 《BMJ (Clinical research ed.)》1958,2(5103):1043-1044
995.
996.
997.
I. R. Munro 《CMAJ》1975,113(6):531-535
A craniofacial team has been developed to corrdinate the treatment of patients with severe facial deformity and to minimize the surgical risks. Two hundred patients have been evaluated in the last 4 years and more than 100 treated by this team to correct orbital hypertelorism, oxycephaly and plagiocephaly with exophthalmos, features of Crouzon''s disease and Apert''s and Treacher Collins syndromes, hemifacial microsomia, and severe lower facial deformity and malocclusion. Surgical principles include extensive subperiosteal stripping of bone, osteotomy as necessary, and repositioning maintained by bone grafts. Postoperative evaluation is being maintained for 5 years or to maturity in younger children. Although many of the results are less than perfect, there has been sufficient improvement, especially psychologic and functional, to warrant continuation of the surgical program under closely controlled conditions. 相似文献
998.
999.
1000.