Recent climate tendencies on an East Antarctic ice shelf inferred from a shallow firn core network.

Nearly three decades of stable isotope ratios and surface mass balance (SMB) data from eight shallow firn cores retrieved at Fimbul Ice Shelf, East Antarctica, in the Austral summers 2009-2011 have been investigated. An additional longer core drilled in 2000/2001 extends the series back to the early eighteenth century. Isotope ratios and SMB from the stacked record of all cores were also related to instrumental temperature data from Neumayer Station on Ekström Ice Shelf. Since the second half of the twentieth century, the SMB shows a statistically significant negative trend, whereas the δ18O of the cores shows a significant positive trend. No trend is found in air temperature at the nearest suitable weather station, Neumayer (available since 1981). This does not correspond to the statistically significant positive trend in Southern Annular Mode (SAM) index, which is usually associated with a cooling of East Antarctica. SAM index and SMB are negatively correlated, which might be explained by a decrease in meridional exchange of energy and moisture leading to lower precipitation amounts. Future monitoring of climate change on the sensitive Antarctic ice shelves is necessary to assess its consequences for sea level change. KEY POINTS: Mass balance and stable oxygen isotope ratios from shallow firn coresDecreasing trend in surface mass balance, no trend in stable isotopesNegative correlation between SAM and SMB.

In situ detection of potassium atoms in high-temperature coal-combustion systems using near-infrared-diode lasers.

Direct tunable diode laser absorption spectroscopy at 769.9 and 767.5 nm was used to measure potassium (K) atom concentrations in situ in the high temperature (up to 1650 K) flue gas of two different pulverized coal dust combustion systems (atmospheric or pressurized (12 bar)). Two laser types (Fabry-Pérot (FP) and vertical-cavity surface-emitting lasers (VCSEL)) were used for the spectrometer and characterized with respect to the magnitude and linearity of their static and dynamic wavelength tuning properties. The wide continuous current-induced tuning range of the VCSEL of 20 cm(-1) (compared to 1 cm(-1) for the FP) make this laser ideal for species monitoring in high pressure processes. Two VCSELs were time-multiplexed to realize the simultaneous detection of the potassium D1 and D2 lines. Several oxygen absorption lines in the A-band, which are in close spectral vicinity of the K lines, were detected simultaneously, showing the possibility of multi-species detection with one laser. Using the FP-DL for the atmospheric process and the VCSEL for the high pressure process, the pressure-dependent coefficients for spectral broadening as well as a shift of the K line in the flue gas were determined to be (0.18 +/- 0.01) and (-0.060 +/- 0.003) cm(-1) per atm (at 1540 K and 11.2 bar). The total width and shift of the D1 line (11.2 bar/1540 K) were 60 and -20 GHz, respectively. The K atom concentration was determined continuously for several days in both plants under various operation conditions. Typical concentrations in the atmospheric plant were around 2 microg m(-3) with a range of 50 ng m(-3)-30 microg m(-3). Averaging 100 scans for each concentration value, we achieved a time resolution of 1.7 s and a detection limit of 10 ng m(-3), which corresponds to a fractional absorption in the 10(-3)-10(-4) range. A strong anti-correlation with the oxygen concentration could be verified. At the 12 bar plant, the concentration was again typically around 2 microg m(-3) but K levels up to 60 microg m(-3) were observed. Here, a strong dependence of the K-signal on the type of fuel could be verified.

Augmentative and alternative communication for persons with developmental disabilities

Communication has been described as the essence of human life. AAC approaches may be grouped into those that are aided of unaided. AAC should be considered for individuals with a variety of developmental disabilities. It is best to start AAC use as early as possible, rather than waiting until an individual may or may not meeting what some authors have called cognitive prerequisites. Possible outcomes of AAC use are: increased communicative competence, improved speech development, replacement of challenging behaviors, and an overall enhancement of the user`s quality of life. Basic components of an AAC assessment and commonly used intervention strategies have been developed. AAC intervention should be goal-drive, needs-based, and accompanied by a way of measuring progress to ensure accountability. The Ontario AAC services system includes a number of funding sources and types of support

The intra-oral camera, dental health communication and oral hygiene.

This study aimed to determine the effectiveness of oral-hygiene instruction in improving oral health in 100 patients following oral hygiene instruction, with and without use of an intra-oral camera. The two groups of 50 patients were similar in age and sex distributions, frequency of caries, plaque accumulation and gingival bleeding. Prospective improvements in oral hygiene and compliance were measured by means of plaque levels and gingival bleeding at baseline and four weeks later. While both groups showed a clear reduction in plaque accumulation, the test group benefited from the use of the intra-oral camera. A majority of patients (88 per cent) thought that the extra information provided by the camera was helpful and desirable. This study demonstrates that the intra-oral camera can effectively augment oral-hygiene instruction and help create improvements in patient compliance.

Investigation of the fumarate metabolism of the syntrophic propionate-oxidizing bacterium strain MPOB.

The growth of the syntrophic propionate-oxidizing bacterium strain MPOB in pure culture by fumarate disproportionation into carbon dioxide and succinate and by fumarate reduction with propionate, formate or hydrogen as electron donor was studied. The highest growth yield, 12.2 g dry cells/mol fumarate, was observed for growth by fumarate disproportionation. In the presence of hydrogen, formate or propionate, the growth yield was more than twice as low: 4.8, 4.6, and 5.2 g dry cells/mol fumarate, respectively. The location of enzymes that are involved in the electron transport chain during fumarate reduction in strain MPOB was analyzed. Fumarate reductase, succinate dehydrogenase, and ATPase were membrane-bound, while formate dehydrogenase and hydrogenase were loosely attached to the periplasmic side of the membrane. The cells contained cytochrome c, cytochrome b, menaquinone-6 and menaquinone-7 as possible electron carriers. Fumarate reduction with hydrogen in membranes of strain MPOB was inhibited by 2-(heptyl)-4-hydroxyquinoline-N-oxide (HOQNO). This inhibition, together with the activity of fumarate reductase with reduced 2,3-dimethyl-1,4-naphtoquinone (DMNH2) and the observation that cytochrome b of strain MPOB was oxidized by fumarate, suggested that menequinone and cytochrome b are involved in the electron transport during fumarate reduction in strain MPOB. The growth yields of fumarate reduction with hydrogen or formate as electron donor were similar to the growth yield of Wolinella succinogenes. Therefore, it can be assumed that strain MPOB gains the same amount of ATP from fumarate reduction as W. succinogenes, i. e. 0.7 mol ATP/mol fumarate. This value supports the hypothesis that syntrophic propionate-oxidizing bacteria have to invest two-thirds of an ATP via reversed electron transport in the succinate oxidation step during the oxidation of propionate. The same electron transport chain that is involved in fumarate reduction may operate in the reversed direction to drive the energetically unfavourable oxidation of succinate during syntrophic propionate oxidation since (1) cytochrome b was reduced by succinate and (2) succinate oxidation was similarly inhibited by HOQNO as fumarate reduction.

Retention of thrombin by polytetrafluoroethylene: influence on the adsorption of fibrinogen/fibrin.

Beads of polytetrafluoroethylene were used to investigate adsorption of thrombin and the influence of the adsorbed protease on a subsequent deposition of fibrinogen. Adsorption of active thrombin was not detected by a specific fluorogenic substrate unless > 0.1 units/ml had been applied. Adsorption was considerably improved by albumin, which protected soluble thrombin from inactivation by hydrophobic surfaces. Retention of active thrombin was optimal at ca. 0.1% albumin and decreased at higher concentrations. After incubation with plasma, negligible thrombin activity was detected at the polytetrafluoroethylene beads by the fluorogenic substrate. However, repeated incubation with fresh plasma samples resulted in adsorbed activity rising with each step. This result suggested that thrombin activity should also accumulate at a polytetrafluoroethylene surface in vivo if fresh blood is permanently flowing past. Adsorbed thrombin improved the subsequent retention of fibrinogen, monitored by an antibody technique. Concomitantly, fibrinopeptides A, AP and AY were slowly released whilst fibrinopeptide B was not detectable before 24 h.

Increased hyaluronate synthesis is required for fibroblast detachment and mitosis.

Human-embryo fibroblasts were synchronized by means of colchicine and cytochalasin, and the production of hyaluronate was determined by [3H]glucosamine incorporation and ion-exchange chromatography. Cells arrested by colchicine synthesized small amounts of hyaluronate, whereas cells blocked by cytochalasin were stimulated in hyaluronate production. When the colchicine block was released, there was an increased synthesis of hyaluronate, which appeared first in the cellular fraction and was then shed into the culture medium. After release of the cytochalasin block, the hyaluronate production declined to that found with unsynchronized cells. A comparable increase of hyaluronate synthase activity was observed during mitosis. When hyaluronate synthesis was blocked by periodate-oxidized UDP-glucuronic acid, the cells were arrested in mitosis before rounding of cells. These results suggest that hyaluronate synthesis is required for detachment and rounding of cells during mitosis.

Role of glycosidases in the membranlytic, antifungal action of Saponins.

In studies on the membranlytic action of various saponins on mycelium of Botrytis cinerea and Rhizoctonia solani digitonin, alpha-hederin and tomatin caused considerable leakage of free amino acids, while aescin and theasaponin were less effective. Cyclamin significantly damaged cell membranes of R. solani, but did not change the selective permeability of B. cinerea. Cell membrane disruption was accompanied by an enzymatic conversion of saponins into their corresponding aglycones in cell membrane vicinity, an effect which was significantly inhibited by aldonolactones, known inhibitors of beta-glycosidases. These results lead to the conclusion that the hardly water soluble aglycones are the active part of the saponin molecules, the saponins themselves being only water soluble transport forms. It follows, that the presence of appropriate glycosidases in cell membranes, capable of converting saponins into their aglycones, is a prerequisite for the membranlytic action of saponins. The similarity of the membranlytic effects of saponins towards fungi and erythrocytes is descussed.

Sterols and the sensitivity of Pythium species to filipin.

Schlosser, Eckart (University of Illinois, Urbana), and David Gottlieb. Sterols and the sensitivity of Pythium species to filipin. J. Bacteriol. 91:1080-1084. 1966.-The growth of several Pythium species was not affected by filipin. No leakage of inorganic phosphate was observed after treatment with the antibiotic. No sterol could be detected in 1 g (dry weight) of mycelium. Thus, the insensitivity of these fungi to the antibiotic may be explained by the lack of sterols, the postulated reaction site for filipin in the cell membrane. Though not capable of synthesizing sterols, Pythium species can incorporate exogeneous sterols, which renders them sensitive to filipin; such treatment causes a lag in growth and leakage of inorganic phosphate. The leakage after filipin treatment is indirect evidence that the sterols have been incorporated into the cell membrane. Induced sensitivity to filipin was reversible; it was lost when the sterols were diluted out by one transfer through a medium free from sterols. The hypothesis that the primary site of interaction of filipin is the sterol located in the cell membrane was strengthened by these studies. The experiments further demonstrated a change in sensitivity of a fungus to a toxic agent due to nutritional conditions.