Untapped Knowledge about Water Reuse: the Roles of Direct and Indirect Educational Messaging

Water Resources Management - Public awareness of water quality concerns has increased since the Flint, MI crisis, but knowledge about water resources management remains low. Consequently,...     

Effect of acute increases in filtered HCO3- on renal hydrogen transporters: II. H(+)-ATPase

Adaptive increases in renal bicarbonate reabsorption occur in response to acute increases in filtered bicarbonate (FLHCO3). In a previous study, we showed that an increase in FLHCO3 induced by plasma volume expansion increased the Vmax for Na+/H+ exchange activity in renal cortical brush border membrane vesicles (BBMV), providing a potential mechanism for the adaptive increase in HCO3- reabsorption. The present studies were undertaken to determine whether the increase in FLHCO3 induced by plasma expansion also stimulates the other major H+ transporter in cortical BBMV, the H(+)-ATPase. H(+)-ATPase activity was assessed in BBMV obtained from hydropenic and plasma expanded Munich-Wistar rats, using a NADH-linked ATPase assay. H(+)-ATPase activity was measured as the ouabain and oligomycin-insensitive, bafilomycin A1-sensitive component of total ATPase activity. Acute plasma expansion doubled single nephron FLHCO3, and this change was associated with a 64% increase in the Vmax for H(+)-ATPase activity, with no change in apparent Km. The Vmax for H(+)-ATPase activity correlated directly with whole kidney GFR and FLHCO3 (r = 0.68 and 0.72, respectively), and with single nephron GFR and FLHCO3 (r = 0.76 and 0.80, respectively). Thus, the mechanism for the adaptive increase in proximal tubular HCO3- reabsorption that occurs in response to acute increases in FLHCO3 appears to be related to increased activity of both H(+)-ATPase and Na+/H+ exchange in the apical membrane of the proximal tubule epithelium.     

Primary afferent depolarizations of sensory origin within contact-sensitive mechanoreceptive afferents of a crayfish leg

Recordings from the central branches of single identified dactyl sensory afferent (DSA) neurons in a crayfish in vitro preparation were performed to study modifications of the sensory message occurring before the first central synapse. These afferents comprised hairs and force-sensitive mechanoreceptors with phasic and phasotonic response characteristics in the terminal segment (dactyl) of the crayfish leg. More than one afferent spike size was often observed in intracellular recordings from these afferents, thus indicating the presence of electrical coupling between the central processes of DSA fibers. Additionally, in identified DSA fibers with large spike sizes, primary afferent depolarizations (PADs) of up to 15 mV were observed, which sometimes triggered antidromic spikes in the afferent. Nevertheless, PADs were clearly inhibitory, because they shunted the afferent spikes. They exhibited the following properties. First, each PAD was preceded by an afferent spike from a neighboring hair, indicating that the PADs had a sensory rather than central origin. Second, PADs could follow high frequencies of afferent discharges without failure, a property suggestive of monosynaptic connections, but because PAD latencies varied by +/-0.5 ms it is more likely that they were mediated by a disynaptic pathway. Third, although PADs were evoked in an extremely reliable manner, their amplitude varied in a quantal manner. Most unitary PADs were the result of the release of < 12 quanta, the mean quantal content lying between 4 and 5; quantal size was large, approximately 1 mV. Fourth, PADs showed facilitation in some fibers, whereas in others they became much smaller when occurring at brief intervals. We suggest that PADs may be an efficient and parsimonious way to limit sensory inflow in space and time, allowing the crayfish to identify precisely both weak and strong mechanical stimuli.     

The effect of particle distribution on damage formation in particulate reinforced metal matrix composites deformed in compression

Image analysis results are reported on the generation of damage in particulate reinforced metal matrix composites during compressive deformation. The technique allows the automated collection of data on the incidence of particle fracture and void formation in the matrix as a function of important microstructural parameters such as local particle volume fraction and particle size. There is a strong relationship between damage and the local volume fraction of the reinforcement proving that damage formation is accentuated in regions of particle clustering. With the SiC reinforced materials examined, there was observed to be a change in dominance of damage mechanism from particle fracture at low local volume fractions to void formation in the matrix within strongly clustered regions. The results are compared with finite element (FE) modelling of the compressive deformation of clustered particles using a simple cluster of equi-spaced particles. The FE results suggest that plastic flow is generally inhibited in clustered regions. In certain highly clustered configurations shielding is such that flow does not occur in the heart of the cluster even at high levels of average plastic strain. The modelling suggests that the change in dominance of damage mechanism is related to the dramatic increase in tensile hydrostatic stresses in the matrix with higher levels of particle clustering.     

Fetal fast MR imaging: reproducibility, technical quality, and conspicuity of anatomy

PURPOSE: To evaluate the normal appearance of fetal anatomy, the conspicuity of fetal organs, the reproducibility of images, and the limitations to image quality with the use of half-Fourier, single-shot rapid acquisition with relaxation enhancement (RARE) magnetic resonance (MR) imaging. MATERIALS AND METHODS: Fifty-four fetuses of 49 pregnancies underwent MR imaging with the half-Fourier, single-shot RARE technique. Two reviewers attempted to identify 47 organs and anatomic regions in each fetus. Organ or region conspicuity, image quality, and the limitations of image quality were graded. RESULTS: Fetal anatomy was well depicted in fetuses over 20 weeks in gestational age. Fetal imaging was limited by gestational age of 20 weeks or less usually owing to the small size of the organ or region being evaluated and, less frequently, by motion. CONCLUSION: Half-Fourier, single-shot RARE MR imaging provided a detailed and reproducible evaluation of normal fetal anatomy, which can be used as a standard of reference in MR imaging of fetal anomalies.     

Families of ergodic and exact one-dimensional maps

We give a parametrized family of rational interval maps of degree two, each ergodic, exact and preserving a measure equivalent to a Lebesgue measure. The family includes the unique quadratic Chebyshev polynomial as its only polynomial map. We extend the family to other settings on the circle and real line. We also give numerical approximations to the entropy of the equivalent invariant measure and the Hausdorff dimension of the singular measure of maximal entropy.     

Juvenile chronic arthritis: a cephalometric analysis of the facial skeleton

A retrospective cross-sectional cephalometric investigation was undertaken to examine the facial form of a group of Finnish children with juvenile chronic arthritis (JCA). Following digitization, the radiographs were divided into three age groups, and according to whether or not 'bird-face' deformity was present. From a total of 67 cases (39 females and 28 males) 19 per cent were judged to be 'affected'. Analyses were carried out and the groups compared using t-tests. The mandible was found to be smaller both in ramal height and body length in the affected sample, with reduction in posterior face height being only partly compensated by increase in bony apposition at the angle producing antegonial notching. There was posterior rotation of the mandible with a reduction in angles S-N-B and S-N-Pog, and an increase in the gonial angle, the angle between the mandibular plane and S-N, maxillary, and occlusal planes. The changes in the maxilla were less marked. Although S-N-A was reduced in all three age groups, it was not significantly so. Maxillary length (ANS-PNS) was significantly smaller in the two younger age groups. In the vertical plane maxillary dimensions were reduced in the two younger age groups. A highly significant increase in the occlusal to maxillary planes angle was observed in all groups. There was, however, no difference in S-N to maxillary planes angle, indicating a more steeply inclined occlusal plane due to subnormally erupted maxillary molars. Although the inter-incisal angle was reduced there was no significant difference in the incisor inclinations in relation to the jaws and despite the posterior rotation of the mandible there was no significant increase in size of overjet or in the frequency of anterior open bite.     

Evidence for 3-D/2-D Transition in Advanced Interconnects

Electrical, electrooptical, mechanical, and microstructural characterizations explain why the leakage currents in advanced Cu/ultralow-interconnects can change from bulk (3-D) to mostly interfacial (2-D) above 150degC. A physical model consistent with all these results is proposed.