Effects of space cabin environments on infection Final report, 19 Jul. 1965 - 18 Sep. 1966

Infection resistance and radiation effects on mice determined after varied exposures to space cabin environment and ambient condition

A laboratory scale model technique for investigating pneumatic tire hydroplaning

Laboratory scale model technique for investigating pneumatic tire hydroplanin

Migration and Trade

Theoretical and empirical research in economics suggests that bilateral migration triggers bilateral trade through a number of channels. This paper assesses the functional form of the impact of migration on trade flows in a quasi-experimental setting. We provide evidence that the relationship is not log-linear. In particular, at small levels of migration (stocks) the elasticity of trade to migration is quite high, and it declines to zero at about 4,000 immigrants. If migration stocks exceed such a level, the evidence suggests that trade will not increase anymore. This suggests that cross-country network and other effects flowing from migration materialize at relatively low levels of migration, but there appears to be satiation as immigrant numbers increase by much.migration, bilateral trade, quasi-randomized experiment, generalized propensity score estimation

Postsynaptic density 95 controls AMPA receptor incorporation during long-term potentiation and experience-driven synaptic plasticity

The regulated delivery of AMPA-type glutamate receptors (AMPARs) to synapses is an important mechanism underlying synaptic plasticity. Here, we ask whether the synaptic scaffolding protein PSD-95 (postsynaptic density 95) participates in AMPAR incorporation during two forms of synaptic plasticity. In hippocampal slice cultures, the expression of PSD-95-green fluorescent protein (PSD-95-GFP) increases AMPAR currents by selectively delivering glutamate receptor 1 (GluR1)-containing receptors to synapses, thus mimicking long-term potentiation (LTP). Mutational analysis shows that the N terminal of PSD-95 including the first two PDZ [PSD-95/Discs large (Dlg)/zona occludens-1 (ZO-1)] domains is necessary and sufficient to mediate this effect. Further supporting a role in synaptic plasticity, wild-type PSD-95 occludes LTP and dominant negative forms block LTP. Moreover, we demonstrate that PSD-95 also participates in AMPAR delivery during experience-driven plasticity in vivo. In the barrel cortex from experience-deprived animals, the expression of PSD-95-GFP selectively increases AMPAR currents, mimicking experience-driven plasticity. In nondeprived animals, PSD-95-GFP produces no additional potentiation, indicating common mechanisms between PSD-95-mediated potentiation and experience-driven synaptic strengthening. A dominant negative form of PSD-95 blocks experience-driven potentiation of synapses. Pharmacological analysis in slice cultures reveals that PSD-95 acts downstream of other signaling pathways involved in LTP. We conclude that PSD-95 controls activity-dependent AMPAR incorporation at synapses via PDZ interactions not only during LTP in vitro but also during experience-driven synaptic strengthening by natural stimuli in vivo

A systematic experimental investigation of significant parameters affecting model tire hydroplaning

The results of a comprehensive parametric study of model and small pneumatic tires operating on a wet surface are presented. Hydroplaning inception (spin down) and rolling restoration (spin up) are discussed. Conclusions indicate that hydroplaning inception occurs at a speed significantly higher than the rolling restoration speed. Hydroplaning speed increases considerably with tread depth, surface roughness and tire inflation pressure of footprint pressure, and only moderately with increased load. Water film thickness affects spin down speed only slightly. Spin down speed varies inversely as approximately the one-sixth power of film thickness. Empirical equations relating tire inflation pressure, normal load, tire diameter and water film thickness have been generated for various tire tread and surface configurations