Pocket PC-based portable gamma-ray spectrometer

A portable gamma-ray spectrometer based on a Pocket PC has been developed. A 12-bit pipeline analog-to-digitalconverter (ADC) associated with an implemented pulse height histogram function on field programmable gate array (FPGA)operating at 15 MHz is employed for pulse height analysis from built-in pulse amplifier. The system, which interfaces withthe Pocket PC via an enhanced RS-232 serial port under the microcontroller facilitation, is utilized for spectrum acquisition,display and analysis. The pulse height analysis capability of the system was tested and it was found that the ADC integralnonlinearity of ±0.45% was obtained with the throughput rate at 160 kcps. The overall system performance was tested usinga PIN photodiode-CsI(Tl) crystal coupled scintillation detector and gamma standard radioactive sources of Cs-137 andCo-60. Low cost and the compact system size as a result of the implemented logical function are also discussed

Protection of cells from salinity stress by extracellular polymeric substances in diatom biofilms.

Diatom biofilms are abundant in the marine environment. It is assumed (but untested) that extracellular polymeric substances (EPS), produced by diatoms, enable cells to cope with fluctuating salinity. To determine the protective role of EPS, Cylindrotheca closterium was grown in xanthan gum at salinities of 35, 50, 70 and 90 ppt. A xanthan matrix significantly increased cell viability (determined by SYTOX-Green), growth rate and population density by up to 300, 2,300 and 200%, respectively. Diatoms grown in 0.75% w/v xanthan, subjected to acute salinity shock treatments (at salinities 17.5, 50, 70 and 90 ppt) maintained photosynthetic capacity, Fq'/Fm', within 4% of pre-shock values, whereas Fq'/Fm' in cells grown without xanthan declined by up to 64% with hypersaline shock. Biofilms that developed in xanthan at standard salinity helped cells to maintain function during salinity shock. These results provide evidence of the benefits of living in an EPS matrix for biofilm diatoms

Characteristics and turnover of exopolymeric substances in a hypersaline microbial mat

The properties and microbial turnover of exopolymeric substances (EPS) were measured in a hypersaline nonlithifying microbial mat (Eleuthera, Bahamas) to investigate their potential role in calcium carbonate (CaCO3) precipitation. Depth profiles of EPS abundance and enzyme activities indicated that c. 80% of the EPS were turned over in the upper 15-20 mm. Oxic and anoxic mat homogenates amended with low-molecular-weight (LMW) organic carbon, sugar monomers, and different types of EPS revealed rapid consumption of all substrates. When comparing the consumption of EPS with that of other substrates, only marginally longer lag times and lower rates were observed. EPS (5-8%) were readily consumed during the conversion of labile to refractory EPS. This coincided with a decrease in glucosidase activity and a decrease in the number of acidic functional groups on the EPS. Approximately half of the calcium bound to the EPS remained after 10 dialyses steps. This tightly bound calcium was readily available to precipitate as CaCO3. We present a conceptual model in which LMW organic carbon complexed with the tightly bound calcium is released upon enzyme activity. This increases alkalinity and creates binding sites for carbonate and allows CaCO3 to precipitate. Therefore, this model explains interactions between EPS and CaCO3 precipitation, and underscores the critical role of aerobic and anaerobic microorganisms in early diagenesis and lithification processe

Assessment of Composition Management the Case of Moha Soft Drinking Share Company Teklehaimanot Plant

Human resource is the major asset of an organization that managers should essentially \ \ understand its compensation management and practice,. Many literatures point out that compensation has direct effect (either positive or negative) on such variables as turnover, absenteeism, productivity an'd strike that are the main problems of many organizations. In VIew of this, the mam objectives of this study are to investigate the fairness, competitiveness, adequacy, incentive plans and equitability of the compensation policy and practice of the case in MOHA soft drink Share Company Teklehaimanot plant. The in-depth analysis of the problem was undertaken using primary and secondary data. Stratified sampling technique was employed to attain the stated objectives. The study resulted are proposed to be useful for MOHA soft drink Share Company Teklehaimanot plant and its employees in particular and for similar organizations in general.Jimma Universit

Ocean acidification affects marine chemical communication by changing structure and function of peptide signalling molecules

Ocean acidification is a global challenge that faces marine organisms in the near future with a predicted rapid drop in pH of up to 0.4 units by the end of this century. Effects of the change in ocean carbon chemistry and pH on the development, growth and fitness of marine animals are well documented. Recent evidence also suggests that a range of chemically mediated behaviours and interactions in marine fish and invertebrates will be affected. Marine animals use chemical cues, for example, to detect predators, for settlement, homing and reproduction. But while effects of high CO₂ conditions on these behaviours are described across many species, little is known about the underlying mechanisms, particularly in invertebrates. Here we investigate the direct influence of future oceanic pH conditions on the structure and function of three peptide signalling molecules with an interdisciplinary combination of methods. NMR spectroscopy and quantum chemical calculations were used to assess the direct molecular influence of pH on the peptide cues and we tested the functionality of the cues in different pH conditions using behavioural bioassays with shore crabs (Carcinus maenas) as a model system. We found that peptide signalling cues are susceptible to protonation in future pH conditions, which will alter their overall charge. We also show that structure and electrostatic properties important for receptor-binding differ significantly between the peptide forms present today and the protonated signalling peptides likely to be dominating in future oceans. The bioassays suggest an impaired functionality of the signalling peptides at low pH. Physiological changes due to high CO₂ conditions were found to play a less significant role in influencing the investigated behaviour. From our results we conclude that the change of charge, structure and consequently function of signalling molecules presents one possible mechanism to explain altered behaviour under future oceanic pH conditions

How do harpacticoid grazing rates differ over a tidal cycle? Field verification using chlorophyll-pigment analyses

Four species of meiobenthic copepods were examined for diatom feeding. Microscopic analysis of gut-pellet contents from field-collected individuals indicated frequent ingestion of diatoms by 3 harpacticoids (Scottolana canadensis, Microarthridion littorale, Cletocamptus deitersi) while occasional diatom ingestion occurred Paronychocamptus huntsmani. Frustules were usually empty and broken, indicating that contents were digested. Laboratory experiments using 14C-labeling showed assimilation of diatoms by the 3 species examined. Field grazing rate studies were conducted over different portions of a tidal cycle using fluorescent chlorophyll-pigment analysis of gut-contents. Highest diatom consumption (p\u3c0.05) occurred just after the mudflat became exposed (i.e. Early Low Water level, ELW) for S. canadensis, while consumption at Late Low Water (LLW, i.e. after mudflat is exposed for several hours) was reduced. M. littorale showed a somewhat similar pattern in that highest consumption rates (p\u3c0.05) also occurred during ELW. However, during High Water (HW) and LLW a similar (but reduced) feeding rate was measured. P. hunstmani appeared to only ingest diatoms (i.e. chl-pigments) during HW. Relationships of feeding processes over a tidal cycle are discussed with regard to distributional patterns in intertidal and subtidal habitats

Water-cover influences on diatom ingestion rates by meiobenthic copepods

Laboratory experiments on meiobenthic copepods using 14C-diatoms were conducted to investigate whether: (1) feeding rates or (2) food sources (planktonically-suspended foods or benthic sediment-associated foods) vary in response to the presence or absence of water-cover (i.e. simulated Higher-water vs Low-water conditions). Three diatom-feeding harpacticoids were examined. Scottolana canadensis feeds at significantly higher rates (2x) during Higher-water (HW) conditions (P\u3c0.001), at which time it consumes planktonic foods; during Low-water (LW), feeding is greatly reduced. These feeding patterns are related to its burrow-dwelling and to its subtidal habitat. Cletocamptus deitersi remains virtually unaffected by changes in ambient water-cover, feeding at nearly equal rates during HW and LW conditions but always tending to consume more benthic diatoms. Microarthridion littorale consumes food at nearly equal rates during HW and LW conditions, but does so by shifting its feeding mode. During HW-times it makes excursions into the water column, feeding on planktonically-suspended foods. During LW-times it feeds benthically, moving over the sediment surface. Such feeding differences must affect meso-scale distributions of meiobenthos in the field, total benthic consumption and energy-flow estimates over a tidal-cycle, and the coupling of benthic and pelagic systems

Effects of deposit-feeding bivalve (Macomona liliana) density on intertidal sediment stability

Effects of macrofaunal feeding and bioturbation on intertidal sediment stability (u*crit) were investigated by manipulating density (0-3 x ambient) of the facultative deposit-feeding wedge shell (Macomona liliana) on the Tuapiro sandflat in Tauranga Harbour, New Zealand. Sediment stability increased up to 200% with decreasing M. liliana density and this was correlated with greater sediment microalgal biomass and mucilage content. The change in stability occurred despite homogeneity of grain size amongst experimental treatments, highlighting the importance of macrofaunal-microbial relationships in determining estuarine sediment erodibility

Image advertising : the art of corporate self-expression

As if they did not already have enough to worry about, corporate managers in recent years have been called on to make decisions in an area that is too seldom covered by their experience and training, and area that seems remote from the profit-and-loss picture. Many companies are asking themselves, How are we being perceived among our various publics? How can we improve our visibility and image? What should that image even be? ... Call it image advertising or public relations, corporate identity is what every company wants yet so few are willing to work at full time