3,945 research outputs found
Sodium–proton exchange in crayfish
AbstractRecently, three proton pump inhibitors were shown to have no effect on proton excretion and little on Na uptake in tapwater-adapted (TW) crayfish, while all three reduced Na–H exchange in salt-depleted (SD) animals. It appeared that the exchange was mediated by the Na channel–H pump in SD crayfish but not in TW animals. An alternative, a 2Na–1H exchanger, might function in the latter.To test this, the effects of amiloride (AM) and ethylisopropyl AM (EIPA) on Na fluxes were observed. AM inhibits the Na channel but is a much weaker blocker of Na–H exchangers. In contrast, EIPA inhibits exchangers but acts weakly on the Na channel. If an exchanger functions in TW crayfish, we should expect EIPA to block Na influx in them with AM having a weaker action. The reverse should be true in SD animals.Experimental data showed that EIPA was a potent inhibitor of Na influx in TW crayfish with half-maximal inhibition at about 0.2 μM. However, AM proved to be equipotent. In SD crayfish, EIPA was as effective as in TW animals, and again AM was equally potent.The data fail to show the expected differential action. Therefore, AM and its analogues cannot be used to distinguish between the two models of Na–H exchange in crayfish
High Energy Quark-Antiquark Elastic scattering with Mesonic Exchange
We studies the high energy elastic scattering of quark anti-quark with an
exchange of a mesonic state in the channel with .
Both the normalization factor and the Regge trajectory can be calculated in
PQCD in cases of fixed (non-running) and running coupling constant. The
dependence of the Regge trajectory on the coupling constant is highly
non-linear and the trajectory is of order of in the interesting physical
range.Comment: 29 page
A rocket ozonesonde for geophysical research and satellite intercomparison
The in-situ rocketsonde for ozone profile measurements developed and flown for geophysical research and satellite comparison is reviewed. The measurement principle involves the chemiluminescence caused by ambient ozone striking a detector and passive pumping as a means of sampling the atmosphere as the sonde descends through the atmosphere on a parachute. The sonde is flown on a meteorological sounding rocket, and flight data are telemetered via the standard meteorological GMD ground receiving system. The payload operation, sensor performance, and calibration procedures simulating flight conditions are described. An error analysis indicated an absolute accuracy of about 12 percent and a precision of about 8 percent. These are combined to give a measurement error of 14 percent
Double logarithms, , and the NLO DGLAP evolution for the non-singlet component of the nucleon spin structure function,
Theoretical predictions show that at low values of Bjorken the spin
structure function, is influenced by large logarithmic corrections,
, which may be predominant in this region. These corrections are
also partially contained in the NLO part of the standard DGLAP evolution. Here
we calculate the non-singlet component of the nucleon structure function,
, and its first moment, using a unified evolution
equation. This equation incorporates the terms describing the NLO DGLAP
evolution and the terms contributing to the resummation. In order
to avoid double counting in the overlapping regions of the phase-space, a
unique way of including the NLO terms into the unified evolution equation is
proposed. The scheme-independent results obtained from this unified evolution
are compared to the NLO fit to experimental data, GRSV'2000. Analysis of the
first moments of shows that the unified evolution including the
resummation goes beyond the NLO DGLAP analysis. Corrections
generated by double logarithms at low influence the -dependence of the
first moments strongly.Comment: 13 pages, latex, 2 figures; Appendix adde
Chemical reactivity of hydrogen, nitrogen and oxygen atoms at temperatures below 100 deg K Fifth semiannual technical report
Chemical reactivity of hydrogen, nitrogen, and oxygen atoms at temperatures below 100 deg
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