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Selected AbstractsLABOUR MARKET REGULATION: SOME COMPARATIVE LESSONSECONOMIC AFFAIRS, Issue 3 2005W. S. Siebert Labour market regulation that undermines freedom of contract leads to fewer, higher productivity jobs with employment being across a narrower range of ages. More people are excluded from the labour market, in highly regulated countries and they remain unemployed for longer. This seems to be damaging to welfare. It is possible that the extent of regulation is explained by the relative ability of those who gain from regulation (those in work) to influence the outcome of political processes to a greater extent than those who lose (the unemployed). However, the legal framework and legal traditions may also play a part. [source] Incorporation of Aluminium and Iron into the Zeolite MCM-58EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 6 2005Gabriela Ko Abstract The hydrothermal synthesis of zeolite MCM-58 is investigated with N -benzylquinuclidinium bromide as a structure-directing agent in order to isomorphously substitute aluminium or iron for silicon. Al-MCM-58 was synthesised in a wide range of nSi/nAl ratios (from 19 to 56), and Fe-MCM-58 was successfully prepared in a narrower range of nSi/nFe ratios (from 18 to 36). The obtained products were characterised by XRD, SEM, 27Al MAS NMR, 29Si MAS NMR, FTIR, and ESR spectroscopy. Two different calcination procedures, viz. in a stream of nitrogen and air or in a stream of ammonia, were used in order to modify the acid sites in the zeolite. FTIR spectroscopy before and after the adsorption of [D3]acetonitrile and pyridine was employed to determine the concentration and type of the acid sites. The acid forms of Al(Fe)-MCM-58 are characterised by the vibrations of bridging Si,OH,Al(Fe) groups at 3628 cm,1 and 3564 cm,1 (Al-MCM-58) or 3646 cm,1 and 3520 cm,1 (Fe-MCM-58). The acid sites of both zeolites Al-MCM-58 and Fe-MCM-58 are accessible for [D3]acetonitrile and pyridine, and all materials contain substantial numbers of Lewis sites (Al-MCM-58: 50,% of the total acid sites; Fe-MCM-58: 90,%) over the whole range of nSi/nAl (nSi/nFe) ratios studied. Only a small increase in the concentration of Brønsted acid sites was achieved after calcination of the as-synthesised samples in a flow of ammonia. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Length and sex-specific associations between spiny dogfish (Squalus acanthias) and hydrographic variables in the Bay of Fundy and Scotian ShelfFISHERIES OCEANOGRAPHY, Issue 2 2002Travis Shepherd The associations between spiny dogfish (Squalus acanthias) and hydrographic variables (temperature, salinity and depth) were examined in the Bay of Fundy and Scotian Shelf from 1970 to 1998. Data were obtained from standard groundfish bottom trawl surveys. Dogfish sex affected habitat associations. Males were found to occupy bottom water of significantly higher salinities and depths than that occupied by females. Length also significantly affected habitat associations. Smaller dogfish occupied relatively deep, high salinity bottom water compared with larger dogfish. Overall, the occupied temperatures, salinities and depths were significantly different from those which were available. Dogfish occupied warmer temperatures along a narrow range (6.62,9.19°C) compared with those which were available (1.57,9.35°C). Occupied salinity (32.70,34.43 ppt) and occupied depth (88.62,184.66 m) were also distributed along a narrower range than available salinity (32.16,34.79 ppt) and available depth (55.00,218.10 m). Sex-specific, length-specific and overall environmental preference by dogfish may bias traditional `offshore' groundfish surveys while large scale changes in hydrographic parameters may alter dogfish distribution and their interactions with other marine fauna. [source] Below-ground carbon flux and partitioning: global patterns and response to temperatureFUNCTIONAL ECOLOGY, Issue 6 2008C. M. Litton Summary 1The fraction of gross primary production (GPP) that is total below-ground carbon flux (TBCF) and the fraction of TBCF that is below-ground net primary production (BNPP) represent globally significant C fluxes that are fundamental in regulating ecosystem C balance. However, global estimates of the partitioning of GPP to TBCF and of TBCF to BNPP, as well as the absolute size of these fluxes, remain highly uncertain. 2Efforts to model below-ground processes are hindered by methodological difficulties for estimating below-ground C cycling, the complexity of below-ground interactions, and an incomplete understanding of the response of GPP, TBCF and BNPP to climate change. Due to a paucity of available data, many terrestrial ecosystem models and ecosystem-level studies of whole stand C use efficiency rely on assumptions that: (i) C allocation patterns across large geographic, climatic and taxonomic scales are fixed; and (ii) c. 50% of TBCF is BNPP. 3Here, we examine available information on GPP, TBCF, BNPP, TBCF : GPP and BNPP : TBCF from a diverse global data base of forest ecosystems to understand patterns in below-ground C flux and partitioning, and their response to mean annual temperature (MAT). 4MAT and mean annual precipitation (MAP) covaried strongly across the global forest data base (37 mm increase in MAP for every 1 °C increase in MAT). In all analyses, however, MAT was the most important variable explaining observed patterns in below-ground C processes. 5GPP, TBCF and BNPP all increased linearly across the global scale range of MAT. TBCF : GPP increased significantly with MAT for temperate and tropical ecosystems (> 5 °C), but variability was high across the data set. BNPP : TBCF varied from 0·26 to 0·53 across the entire MAT gradient (,5 to 30 °C), with a much narrower range of 0·42 to 0·53 for temperate and tropical ecosystems (5 to 30 °C). 6Variability in the data sets was moderate and clear exceptions to the general patterns exist that likely relate to other factors important for determining below-ground C flux and partitioning, in particular water availability and nutrient supply. Still, our results highlight global patterns in below-ground C flux and partitioning in forests in response to MAT that in part confirm previously held assumptions. [source] Microscale vegetation-soil feedback boosts hysteresis in a regional vegetation,climate systemGLOBAL CHANGE BIOLOGY, Issue 5 2008RUUD H. H. JANSSEN Abstract It has been hypothesized that a positive feedback between vegetation cover and monsoon circulation may lead to the existence of two alternative stable states in the Sahara region: a vegetated state with moderate precipitation and a desert state with low precipitation. This could explain the sudden onset of desertification in the region about 5000 years ago. However, other models suggest that the effect of vegetation on the precipitation may be insufficient to produce this behavior. Here, we show that inclusion of the microscale feedback between soil and vegetation in the model greatly amplifies the nonlinearity, causing alternative stable states and considerable hysteresis even if the effect of vegetation on precipitation is moderate. On the other hand, our analysis suggests that self-organized vegetation patterns known from models that only focus at the microscale plant,soil feedback will be limited to a narrower range of conditions due to the regional scale climate-feedback. This implies that in monsoon areas such as the Western Sahara self-organized vegetation patterns are predicted to be less common than in areas without monsoon circulation such as Central Australia. [source] The rise of the ,network organisation' and the decline of discretionHUMAN RESOURCE MANAGEMENT JOURNAL, Issue 2 2003Irena Grugulis This article explores the implications of ,networked' and ,flexible' organisations for the work and skills of professionals/ Drawing on material from four different case studies, it reviews work that is outsourced (involving IT professionals and housing benefit caseworkers), work that is done by teachers contracted to a temporary employment agency and work organised through an inter-firm network (chemical production workers). In each case work that was outsourced was managed very differently to that undertaken in-house, with managerial monitoring replacing and reducing employees' discretion. New staff in these networks had fewer skills when hired and were given access to a narrower range of skills than their predecessors. By contrast, the production staff directly employed on permanent contracts in the inter-firm network were given (and took) significant amounts of responsibility, with positive results for both their skills and the work processed. Yet, despite the negative impact they have on skills, outsourcing and subcontracting are a far more common means of securing flexibility than organisational collaboration. [source] Tectonic control of bioalteration in modern and ancient oceanic crust as evidenced by carbon isotopesISLAND ARC, Issue 1 2006Harald Furnes Abstract We review the carbon-isotope data for finely disseminated carbonates from bioaltered, glassy pillow rims of basaltic lava flows from in situ slow- and intermediate-spreading oceanic crust of the central Atlantic Ocean (CAO) and the Costa Rica Rift (CRR). The ,13C values of the bioaltered glassy samples from the CAO show a large range, between ,17 and +3, (Vienna Peedee belemnite standard), whereas those from the CRR define a much narrower range, between ,17, and ,7,. This variation can be interpreted as the product of different microbial metabolisms during microbial alteration of the glass. In the present study, the generally low ,13C values (less than ,7,) are attributed to carbonate precipitated from microbially produced CO2 during oxidation of organic matter. Positive ,13C values >0, likely result from lithotrophic utilization of CO2 by methanogenic Archaea that produce CH4 from H2 and CO2. High production of H2 at the slow-spreading CAO crust may be a consequence of fault-bounded, high-level serpentinized peridotites near or on the sea floor, in contrast to the CRR crust, which exhibits a layer-cake pseudostratigraphy with much less faulting and supposedly less H2 production. A comparison of the ,13C data from glassy pillow margins in two ophiolites interpreted to have formed at different spreading rates supports this interpretation. The Jurassic Mirdita ophiolite complex in Albania shows a structural architecture similar to that of the slow-spreading CAO crust, with a similar range in ,13C values of biogenic carbonates. The Late Ordvician Solund,Stavfjord ophiolite complex in western Norway exhibits structural and geochemical evidence for evolution at an intermediate-spreading mid-ocean ridge and displays ,13C signatures in biogenic carbonates similar to those of the CRR. Based on the results of this comparative study, it is tentatively concluded that the spreading rate-dependent tectonic evolution of oceanic lithosphere has a significant control on the evolution of microbial life and hence on the ,13C biosignatures preserved in disseminated biogenic carbonates in glassy, bioaltered lavas. [source] A spatial model of coexistence among three Banksia species along a topographic gradient in fire-prone shrublandsJOURNAL OF ECOLOGY, Issue 5 2002J. Groeneveld Summary 1A spatially explicit, rule-based model for three co-occurring Banksia species was developed to investigate coexistence mediating processes in a fire-prone shrubland in western Australia. Fecundity, recruitment, mortality and other biological data for two non-sprouting (B. hookeriana, B. prionotes) and one resprouting (B. attenuata) species were available from 15 years of empirical field studies. 2Without interspecific competition, each species could persist for a wide range of fire intervals (10 to > 20 years). The resprouting species performed better under shorter fire intervals (10,13 years), while both non-sprouting species were favoured by longer (15 to > 20 years) fire intervals. These results conform with those obtained from single-species, non-spatial population models. 3When interspecific competition for space was included in the model, all three species exhibited optima at shorter fire intervals and with a narrower range than in isolation. The three species did not co-occur under any fire regime. At intermediate fire frequencies (11,13 years), B. hookeriana excluded the other species, while for longer intervals between fires B. prionotes became dominant. 4The introduction of temporal (stochastic) variability in fire intervals (drawn from a normal distribution) failed to produce coexistence, unless spatial variability as a spatial ignition gradient was also included. The spatial arrangement of the non-sprouters observed in the field was then reproduced. 5Observed patterns of coexistence and spatial distributions of all species occurred when a spatial establishment gradient for the resprouter species was included in the model (individuals of B. attenuata are known to produce more seeds in swales than on dune crests and recruit seedlings here more frequently). 6Coexistence appears to be highly dependent upon the mean interfire period in combination with subtle gradients associated with fire propagation and recruitment conditions. Variation around the mean fire interval is less critical. When the system is modelled over a long time period (1500 years) coexistence is most strongly favoured for a narrow window of mean fire intervals (12,14 years). [source] Ampicillin micronization by supercritical assisted atomizationJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 11 2003E. Reverchon ABSTRACT The micronization technique called supercritical assisted atomization (SAA) was used to produce ampicillin microparticles with controlled particle size and particle size distribution suitable for aerosol drug delivery. The process is based on the solubilization of supercritical CO2 in a liquid solution. The ternary mixture is then sprayed through a nozzle and, as a consequence of enhanced atomization, solid microparticles are formed. Water and organic solvents were tested with ampicillin to determine the influence of the solvent on the process mechanism. SAA process parameters were studied by testing different supercritical/liquid solvent flow ratios, ampicillin concentrations in the liquid solution and nozzle diameters. The effect of these parameters on morphology, particle size and particle size distribution of microparticles was analysed. Ampicillin particles suitable for aerosol delivery in the size range 1,5 ,m were obtained using buffered water. Moreover, by varying the solute concentration, ampicillin particles in a narrower range (1,3 ,m) than that usually suggested for aerosol deliverable drugs were obtained. This is an example of particle size tailoring by SAA. [source] Rejecting the mean: Estimating the response of fen plant species to environmental factors by non-linear quantile regressionJOURNAL OF VEGETATION SCIENCE, Issue 4 2005Henning K. Schröder Abstract Question: Is quantile regression an appropriate statistical approach to estimate the response of fen species to single environmental factors? Background: Data sets in vegetation field studies are often characterized by a large number of zeros and they are generally incomplete in respect to the factors which possibly influence plant species distribution. Thus, it is problematic to relate plant species abundance to single environmental factors by the ordinary least squares regression technique of the conditional mean. Location: Riparian herbaceous fen in central Jutland (Denmark). Methods: Semi-parametric quantile regression was used to estimate the response of 18 plant species to six environmental factors, 95% regression quantiles were chosen to reduce the impact of multiple unmeasured factors on the regression analyses. Results of 95% quantile regression and ordinary least squares regression were compared. Results: The standard regression of the conditional mean underestimated the rates of change of species cover due to the selected factor in comparison to 95% regression quantiles. The fitted response curves indicated a general broad tolerance of the studied fen species to different flooding durations but a narrower range concerning groundwater amplitude. The cover of all species was related to soil exchangeable phosphate and base-richness. A relationship between soil exchangeable potassium and species cover was only found for 11 species. Conclusion: Considering the characteristics of data sets in vegetation science, non-linear quantile regression is a useful method for gradient analyses. [source] Chemotopic odorant coding in a mammalian olfactory system,THE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 1 2007Brett A. Johnson Abstract Systematic mapping studies involving 365 odorant chemicals have shown that glomerular responses in the rat olfactory bulb are organized spatially in patterns that are related to the chemistry of the odorant stimuli. This organization involves the spatial clustering of principal responses to numerous odorants that share key aspects of chemistry such as functional groups, hydrocarbon structural elements, and/or overall molecular properties related to water solubility. In several of the clusters, responses shift progressively in position according to odorant carbon chain length. These response domains appear to be constructed from orderly projections of sensory neurons in the olfactory epithelium and may also involve chromatography across the nasal mucosa. The spatial clustering of glomerular responses may serve to "tune" the principal responses of bulbar projection neurons by way of inhibitory interneuronal networks, allowing the projection neurons to respond to a narrower range of stimuli than their associated sensory neurons. When glomerular activity patterns are viewed relative to the overall level of glomerular activation, the patterns accurately predict the perception of odor quality, thereby supporting the notion that spatial patterns of activity are the key factors underlying that aspect of the olfactory code. A critical analysis suggests that alternative coding mechanisms for odor quality, such as those based on temporal patterns of responses, enjoy little experimental support. J. Comp. Neurol. 503:1,34, 2007. © 2007 Wiley-Liss, Inc. [source] Enzyme immobilization on ultrafine cellulose fibers via poly(acrylic acid) electrolyte graftsBIOTECHNOLOGY & BIOENGINEERING, Issue 4 2005Hong Chen Abstract Ultrafine cellulose fiber (diameter 200,400 nm) surfaces were grafted with polyacrylic acid (PAA) via either ceric ion initiated polymerization or methacrylation of cellulose with methacrylate chloride (MACl) and subsequent free-radical polymerization of acrylic acid. PAA grafts by ceric ion initiated polymerization increased with increasing reaction time (2,24 h), monomer (0.3,2.4 M), and initiator (1,10 mM) concentrations, and spanned a broad range from 5.5,850%. PAA grafts on the methacrylated cellulose fibers also increased with increasing molar ratios of MACl to cellulosic hydroxyl groups (MACl/OH, 2,6.4) and monomer acrylic acid (AA) to initiator potassium persulfate (KPS) ratios ([AA]/[KPS], 1.5,6), and were in a much narrower range between 12.8% and 29.4%. The adsorption of lipase (at 1 mg/ml lipase and pH 7) and the activity of adsorbed lipase (pH 8.5, 30°C), in both cases decreased with increasing PAA grafts. The highest adsorption and activity of the lipase on the ceric ion initiated grafted fibers were 1.28 g/g PAA and 4.3 U/mg lipase, respectively, at the lowest grafting level of 5.5% PAA, whereas they were 0.33 g/g PAA and 7.1 U/mg lipase, respectively, at 12.8% PAA grafts on the methacrylated and grafted fibers. The properties of the grafted fibers and the absorption behavior and activity of lipase suggest that the PAA grafts are gel-like by ceric-initiated reaction and brush-like by methacrylation and polymerization. The adsorbed lipase on the ceric ion-initiated grafted surface possessed greatly improved organic solvent stability over the crude lipase. The adsorbed lipases exhibited 0.5 and 0.3 of the initial activity in the second and third assay cycles, respectively. © 2004 Wiley Periodicals, Inc. [source] Effect of physical, chemical and environmental characteristics on arbuscular mycorrhizal fungi in Brachiaria decumbens (Stapf) pasturesJOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2008R.H. Posada Abstract Aim:, To evaluate the effects of soil physical and chemical factors (pH, conductivity, humidity, available phosphorus and organic matter) and environmental factors (temperature, relative air humidity, altitude and atmospheric pressure) on arbuscular mycorrhizal fungi (AMF),Brachiaria decumbens grass relationship. Furthermore to establish patterns of microbiological responses that allow to differentiate the study sites in two relief types. Methods and Results:, Mycorrhizal characteristics (spore density, external hyphae and root colonizations by hyphae, vesicles and arbuscules), physical and chemical factors in soil and environmental factors were measured. Conclusions:, The effect of physical, chemical and environmental factors on microbiological variables was related to the type of relief ,valley and hilly terrain'; the AMF behaviour was affected only over narrower ranges of evaluated variables. Similarly, the colonization of B. decumbens roots by AMF hyphae, vesicles and the mycorrhizal spore density follow different patterns according to the relief type. Significance and Impact of the Study:, The type of relief is one of the factors to be taken into consideration to evaluate the AMF inoculum and root colonization of these pastures, because of the influence of slope , as physical property of soil , on AMF. [source] | ||||||||||||||||