1,543 research outputs found
Polarized distribution of HCO3- transport in human normal and cystic fibrosis nasal epithelia
The polarized distribution of HCO3â transport was investigated in human nasal epithelial cells from normal and cystic fibrosis (CF) tissues. To test for HCO3â transport via conductive versus electroneutral Clâ/HCO3â exchange (anion exchange, AE) pathways, nasal cells were loaded with the pH probe 2â˛,7â˛-bis(carboxyethyl)-5(6)-carboxyfluorescein and mounted in a bilateral perfusion chamber. In normal, but not CF, epithelia, replacing mucosal Clâ with gluconate caused intracellular pH (pHi) to increase, and the initial rates (ÎpH minâ1) of this increase were modestly augmented (âź26 %) when normal cells were pretreated with forskolin (10 Îźm). Recovery from this alkaline shift was dependent on mucosal Clâ, was insensitive to the AE inhibitor 4,4â˛-diisothiocyanatodihydrostilbene-2,2â˛-disulfonic acid (H2DIDS; 1.5 mm), but was sensitive to the cystic fibrosis transmembrane conductance regulator (CFTR) channel inhibitor diphenylamine-2-carboxylate (DPC; 100 Îźm). In contrast, removal of serosal Clâ caused pHi to alkalinize in both normal and CF epithelia. Recovery from this alkaline challenge was dependent on serosal Clâ and blocked by H2DIDS. Additional studies showed that serosally applied Ba2+ (5.0 mm) in normal, but not CF, cells induced influx of HCO3â across the apical membrane that was reversibly blocked by mucosal DPC. In a final series of studies, normal and CF cells acutely alkaline loaded by replacing bilateral Krebs bicarbonate Ringer (KBR) with Hepes-buffered Ringer solution exhibited basolateral, but not apical, recovery from an alkaline challenge that was dependent on Clâ, independent of Na+ and blocked by H2DIDS. We conclude that: (1) normal, but not CF, nasal epithelia have a constitutively active DPC-sensitive HCO3â influx/efflux pathway across the apical membrane of cells, consistent with the movement of HCO3â via CFTR; and (2) both normal and CF nasal epithelia have Na+-independent, H2DIDS-sensitive AE at their basolateral domain
Effects of intervention upon precompetition state anxiety in elite junior tennis players: The relevance of the matching hypothesis
Reproduced with permission of publisher from:
Terry, P., Coakley, L., & Karageorghis, C. Effects of intervention upon precompetition state anxiety in elite junior tennis players: the relevance of the matching hypothesis. Perceptual and Motor Skills, 1995, 81, 287-296. Š Perceptual and Motor Skills 1995The matching hypothesis proposes that interventions for anxiety should be matched to the modality in which anxiety is experienced. This study investigated the relevance of the matching hypothesis for anxiety interventions in tennis. Elite junior tennis players (N = 100; Age: M = 13.9 yr., SD = 1.8 yr.) completed the Competitive State Anxiety Inventory-2 before and after one of four randomly assigned intervention strategies approximately one hour prior to competition at a National Junior Championship. A two-factor multivariate analysis of variance (group x time) with repeated measures on the time factor gave no significant main effect by group but indicated significant reductions in somatic anxiety and cognitive anxiety and a significant increase in self-confidence following intervention. A significant group by time interaction emerged for self-confidence. The results question the need to match intervention strategy to the mode of anxiety experienced
Soil carbon and nitrogen and barley yield responses to repeated additions of compost and slurry
The yields of spring barley during a medium-term (7 years) compost and slurry addition experiment and the soil
carbon (C) and nitrogen (N) contents, bacterial community structure, soil microbial biomass and soil respiration
rates have been determined to assess the effects of repeated, and in some cases very large, organic amendments
on soil and crop parameters. For compost, total additions were equivalent to up to 119 t C/ha and 1¡7 t N/ha and
for slurry they were 25 t C/ha and 0¡35 t N/ha over 7 years, which represented very large additions compared to
control soil C and N contents (69 t C/ha and 0¡3 t N/ha in the 0â30 cm soil depth). There was an initial positive
response to compost and slurry addition on barley yield, but over the experiment the yield differential between
the amounts of compost addition declined, indicating that repeated addition of compost at a lower rate over
several years had the same cumulative effect as a large single compost application. By the end of the experiment
it was clear that the addition of compost and slurry increased soil C and N contents, especially towards the top of
the soil profile, as well as soil respiration rates. However, the increases in soil C and N contents were not proportional
to the amount of C and N added, suggesting either that: (i) a portion of the added C and N was more vulnerable
to loss; (ii) that its addition rendered another C or N pool in the soil more susceptible to loss; or (iii) that the
C inputs from additional crop productivity did not increase in line with the organic amendments. Soil microbial
biomass was depressed at the highest rate of organic amendment, and whilst this may have been due to genuine
toxic or inhibitory effects of large amounts of compost, it could also be due to the inaccuracy of the substrate induced respiration approach used for determining soil biomass when there is a large supply of organic
matter. At the highest compost addition, the bacterial community structure was significantly altered, suggesting
that the amendments significantly altered soil community dynamics
Design, analysis and test verification of advanced encapsulation systems, phase 2 program results
Optical, electrical isolation, thermal structural, structural deflection, and thermal tests are reported. The utility of the optical, series capacitance, and structural deflection models was verified
Search for the hero: an investigation into the sports heroes of British sports fans
This is an initial study into British sports fansâ heroes. A questionnaire was sent to 95 students (average age Âź 19.75) to identify their sporting hero, the heroâs sport and nationality and the reasons for this choice. Football was the most common source of sports heroes, identified by 49% of participants with a sporting hero. The majority (60%, N Âź 48) of heroes chosen by participants were British, with David Beckham the most popular choice. Differences were observed between the gender of participants, gender of hero chosen and the reasons for choosing the hero. The most common reason for selecting a hero was a personal trait rather than skill, while in the questionnaire a category of Local Affiliation was added to those suggested by previous work. It was concluded that to become a hero athletes should combine skill with devotion to family, charity work and a place in popular culture
Investigations on the Peach 4 Debrite, a Late Pleistocene Mass Movement on the Northwest British Continental Margin
The Peach 4 debrite is the most recent in a series of large scale Pleistocene MTDs within the Barra fan on the northwest British continental margin. Geophysical data indicate that Peach 4 was formed through a combination of blocky and muddy debris flows and affects an area of ~ 700 km2. BGS core sample 56 -10 36, located directly over the Peach 4 debrite, provides a minimum age of 14.68 ka cal BP for the last major failure. An upwards fining turbidite sequence in BGS core sample 56 -10 239 is associ-ated with increased As and S concentrations, indicators of diagenetic pyrite which forms under anoxic conditions. It is proposed that As and S concentrations may pro-vide a method of distinguishing between contourite and turbidite sedimentation, though further research is required
Precision Measurement of the Radiative Decay of the Free Neutron
The standard model predicts that, in addition to a proton, an electron, and
an antineutrino, a continuous spectrum of photons is emitted in the
decay of the free neutron. We report on the RDK II experiment which measured
the photon spectrum using two different detector arrays. An annular array of
bismuth germanium oxide scintillators detected photons from 14 to 782~keV. The
spectral shape was consistent with theory, and we determined a branching ratio
of 0.00335 0.00005 [stat] 0.00015 [syst]. A second detector array
of large area avalanche photodiodes directly detected photons from 0.4 to
14~keV. For this array, the spectral shape was consistent with theory, and the
branching ratio was determined to be 0.00582 0.00023 [stat] 0.00062
[syst]. We report the first precision test of the shape of the photon energy
spectrum from neutron radiative decay and a substantially improved
determination of the branching ratio over a broad range of photon energies
Casimir-Polder forces, boundary conditions and fluctuations
We review different aspects of the atom-atom and atom-wall Casimir-Polder
forces. We first discuss the role of a boundary condition on the interatomic
Casimir-Polder potential between two ground-state atoms, and give a physically
transparent interpretation of the results in terms of vacuum fluctuations and
image atomic dipoles. We then discuss the known atom-wall Casimir-Polder force
for ground- and excited-state atoms, using a different method which is also
suited for extension to time-dependent situations. Finally, we consider the
fluctuation of the Casimir-Polder force between a ground-state atom and a
conducting wall, and discuss possible observation of this force fluctuation.Comment: 5 page
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