GRB 130427A occured in a relatively nearby galaxy; its prompt emission had the largest GRB fluence ever recorded. The afterglow of GRB 130427A was bright enough for the Nuclear Spectroscopic ...Telescope ARray (NuSTAR) to observe it in the 3-79 keV energy range long after its prompt emission (~1.5 and 5 days). This range, where afterglow observations were previously not possible, bridges an important spectral gap. Combined with Swift, Fermi, and ground-based optical data, NuSTAR observations unambiguously establish a single afterglow spectral component from optical to multi-GeV energies a day after the event, which is almost certainly synchrotron radiation. Such an origin of the late-time Fermi/Large Area Telescope > 10 GeV photons requires revisions in our understanding of collisionless relativistic shock physics.
The reuse of knowledge and information arising from the different phases of a product’s lifecycle is crucial for a company in order to achieve competitive advantage. This paper describes a case study ...from the oil industry investigating the transfer of knowledge within the service phase and also between the service and design phases. Interviews with engineering designers and service engineers were conducted. Knowledge arising from servicing the drilling equipment that was identified as relevant for service engineers was compared to that relevant for engineering designers. Furthermore, the mechanisms involved in the transfer of knowledge between service and design were investigated. Knowledge about changes, issues and improvements generated during service was found to be relevant to both groups; however, engineering designers were interested in knowledge of equipment at a component level whilst service engineers were more interested in obtaining an overview of the systems. The study showed that communication between the departments consisted prevalently of the service engineers pushing knowledge and information to the engineering designers. The reusing service knowledge (RSK) model is proposed based upon the findings and the understanding from a general framework for developing a knowledge management strategy. Additionally, the initial model was revised to explicitly address the factors that emerged from the case study. The RSK model was developed based on a case study from a customised industry; however, previous studies indicated that similar issues are also of relevance to a variant design industry.
Purpose
The existence of black horizons (BHs) is often highlighted in European soils, and in the Po River plain of northern Italy. Nevertheless, BH chronological frameworks and genetic models are ...still debated. The present study investigated the genesis of BHs in the eastern Po Plain where they are buried at various depths.
Materials and methods
Soil sequences were investigated with a multidisciplinary approach integrating geomorphologic, stratigraphic, pedologic, geochemical, isotopic, palynological, and radiometric analyses.
Results and discussion
The formation of the studied BHs was scattered over time from the Last Glacial Maximum to at least the middle Holocene. The new data indicate that BHs developed when the landscape was dominated by coniferous forest during conditions that were totally different from the current pedoclimatic setting. The recurrent presence of black particles indicates that this vegetation cover was systematically affected by fire episodes that induced soil degradation and mineralization processes of the original organic compounds, thus contributing to darkening of the upper soil horizons.
Conclusions
BH formation clearly coincided with cold time lapses. Evidence for repeated fire events (natural or human-induced?) provides insights for the controversial debate on early anthropogenic impacts on the environment.
This paper aims to investigate the knowledge generated during the later phases of the life cycle of a complex customised product and understand how this knowledge is transferred between projects and ...between different user groups. A series of four identical rigs for offshore drilling was selected as a case study, and the transfer of knowledge between the first two rigs was explored through two sets of interviews with the rig operators and the project management team. The expected knowledge transfer strategies that emerged from the first set of interviews were analysed and compared with the actual transfer mechanisms identified in the second set of interviews, and similarities and differences were investigated. It was found that the transfer of knowledge primarily occurred within the individual phases of the product’s life cycle, and there was poor transfer across the different phases.
On 2009 January 22 numerous strong bursts were detected from the anomalous X-ray pulsar 1E 1547.0-5408. Swift/XRT and XMM-Newton/EPIC observations carried out in the following two weeks led to the ...discovery of three X-ray rings centered on this source. The ring radii increased with time following the expansion law expected for a short impulse of X-rays scattered by three dust clouds. Assuming different models for the dust composition and grain size distribution, we fit the intensity decay of each ring as a function of time at different energies, obtaining tight constraints on the distance of the X-ray source. Although the distance strongly depends on the adopted dust model, we find that some models are incompatible with our X-ray data, restricting to 4-8 kpc the range of possible distances for 1E 1547.0-5408. The best-fitting dust model provides a source distance of 3.91 +- 0.07 kpc, which is compatible with the proposed association with the supernova remnant G327.24-0.13, and implies distances of 2.2 kpc, 2.6 kpc and 3.4 kpc for the dust clouds, in good agreement with the dust distribution inferred by CO line observations toward 1E 1547.0-5408. However, dust distances in agreement with CO data are also obtained for a set of similarly well-fitting models that imply a source distance of {approx}5 kpc. A distance of {approx}4-5 kpc is also favored by the fact that these dust models are already known to provide good fits to the dust-scattering halos of bright X-ray binaries. Assuming N{sub H} = 10{sup 22} cm{sup -2} in the dust cloud responsible for the brightest ring and a bremsstrahlung spectrum with kT = 100 keV, we estimate that the burst producing the X-ray ring released an energy of 10{sup 44}-10{sup 45} erg in the 1-100 keV band, suggesting that this burst was the brightest flare without any long-lasting pulsating tail ever detected from a magnetar.
This paper examines the issues related to salinization and water quality in the complex drainage system of the historical land reclamation of Lamone basin (Ravenna coastal plain, northern Italy), ...with the aim of guiding ongoing agricultural-related decisions. Major and trace element concentration and O–H–B–Sr isotope-ratios were measured on surface water from a network of canals and ditches. Sampling was carried out during the winter period and in summer, to assess the effects of agricultural water management on the aquatic system. Results show widespread salinization of waters over the entire crop, due to both the direct saltwater inland flushing through the canals in proximity of the mouths, and sea salt leaching from soils. During winter, salinization is partly mitigated by rainfalls, while in summer dilution processes are due to freshwater input from outside the watershed, planned to assist the agricultural water demand. In the winter season, the concentration of some elements such as Fe, Mn, Al, and Cu in waters exceeds the maximum permissible limits imposed by the Italian regulations, while during summer the concentration of these elements is significantly reduced. A seasonal cycling is established, where the bottom sediments of canals and ditches act as sinks of harmful elements, mostly through adsorption by Fe–Mn–Al oxy-hydroxide solid phases. The irrigation practice, although improving the water quality, increases water turbidity by re-mobilization of sediments which act as transport agents of contaminants, with detrimental effects that may become significant over the years.
The aim of the study was to analyse the pedological, chemical and biochemical properties of soil in order to assess the effect of plant cover species (chestnut, Douglas-fir and mixed vegetation) on ...soil processes. The selected area under Douglas-fir reforestation was homogeneous for climate, morphology and parent material. The study involved three soils: under chestnut forest (CS), Douglas-fir reforestation (DF) and the transition zone (T). A soil profile differentiation occurred after 50 years of Douglas-fir plantation. The thickness of soil horizons at the surface varied, and the OH horizon in T site was fourfold thicker than that in DF site. The A1 mineral horizon in T site was also thicker than that in DF site. The Munsell value of mineral horizons was significantly lower in DF than CS site. Morphological differences (thickness and colour) probably reflect soil organic matter quality changes: in DF higher values of humification index were found in surface layers (OF/OH or OH and A1) and lower in deep organo-mineral and transition horizons (A2 and BA or AB) with respect to CS site. Also, a slight increase of weathering process was observed under Douglas-fir reforestation. The morphological, chemical and biological properties of soil were effective to assess the impact of various vegetation types on soil organic matter properties related to pedogenetic process. The various methodological approaches allow studying soil processes using a small–medium spatial scale sampling scheme.
The aim of the work was to propose a new methodological approach that relates soil microbial functional diversity to soil development under different moisture regimes. As soil evolution proceeds ...through an increasing niche separation we expect a link between functional diversity and soil development. Shannon's (H') and Gini (D) diversity indices were calculated using eight enzyme activities (β-cellobiohydrolase, N-acetyl-β-glucosaminidase, β-glucosidase, α-glucosidase, acid phosphatase, arylsulfatase, xylosidase and butyrate esterase) in order to assess functional diversity at different scales, from soil horizons (α-diversity) to soil profiles (β-diversity) under different moisture regime (γ-diversity) and belonging to different taxonomic levels. In addition, the ratio of acid phosphatase to chitinase was calculated as a potential index of soil development. Eight soil profiles were selected: four in Northwestern Italian Alps or Northern Apennines with Udic soil moisture regimes (Typic Haplocryod, Mollic Haplocryept, Lithic Dystrudept, Lithic Cryorthent) and four in Northeastern Italy where in two cases the water table near the soil surface strongly affects the Ustic soil moisture regime, and intrazonal Aquic regime or Aquic conditions develop (Typic Haplustept, Typic Ustipsamment, Aquic Ustipsamment, Typic Psammaquent). D ranged from 50 to 95%, while the H' ranged from 3 to 2.4 in Lithic Cryorthent and Typic Psammaquent, respectively. Under Udic moisture regime an inverse relationship between soil profile development and the diversity index was observed. However the lowest the diversity in the profile, the highest the variability of the values obtained within horizons in the soil profile suggesting a link between differentiation of soil horizons and biochemical properties. The Aquic conditions interfere in establishing the relationship between soil profile development and the microbial functional diversity since H' and D increased in Typic Psammaquent with respect to Typic Haplustept (H' from 2.4 to 2.6 and D from 52.2 to 60.4). Finally, the phosphatase/chitinase ratio was related to soil development since the lowest values were obtained in the upper horizons of Typic Haplustept, Typic and Aquic Ustipsamment (from 2.0 to 4.0), while the highest values were obtained in deep horizons of Typic Haplocryod and Lithic Dystrudept (e.g. 39.2 in Bs2 and 28.0 in Bw1). In conclusion, microbial functional diversity assessed using Shannon or Gini diversity indices and phosphatase/chitinase ratio measured at different scales from soil horizons to soil profiles under different moisture regime and belonging to different taxonomic levels, may represent a new approach to establish the interrelationship between pedogenetic processes, soil development and soil microbial functions.
► Shannon's (H) and Gini (D) diversity indices were used to assess soil microbial functional diversity ► H and D include eight enzyme activities from soil horizons at different taxonomic levels ► An inverse relationship between soil development and the microbial diversity index was found ► Aquic regime interfered with the above mentioned relationship ► Microbial functional diversity might be linked to the highest entropy of young undeveloped soils.
Two new expanding X-ray rings were detected by the Swift XRT instrument during early follow-up observations of GRB 061019 and GRB 070129, increasing to 5 the number of dust scattering X-ray halos ...observed around GRBs. Although these two halos were particularly faint, a sensitive analysis can be performed that optimizes the method originally developed by Tiengo & Mereghetti (2006, A&A, 449, 203) to analyze dust scattering rings observed with XMM-Newton for the Swift satellite. In the case of GRB 061019, a known giant molecular cloud is identified as the one responsible for the scattering process, and its distance is accurately measured (d = 940 ± 40 pc) through the dynamics of the expanding ring. In the second case, XRT observed both the main peak of the prompt emission of GRB 070129 and the scattering halo, but the small number of detected halo photons prevents us from distinguish between different dust models.
In 2009 January, multiple short bursts of soft gamma rays were detected from the direction of the anomalous X-ray pulsar 1E 1547.0-5408 by different satellites. Here we report on the observations ...obtained with the Anti Coincidence Shield (ACS) of the SPI instrument on INTEGRAL during the period with the strongest bursting activity. More than 200 bursts were detected at energies above 80 keV in a few hours on January 22. Among these, two remarkably bright events showed pulsating tails lasting several seconds and modulated at the 2.1 s spin period of 1E 1547.0-5408. The energy released in the brightest of these bursts was of a few 1043 erg, for an assumed distance of 10 kpc. This is smaller than that of the three giant flares seen from soft gamma-ray repeaters (SGRs), but higher than that of typical bursts from SGRs and anomalous X-ray pulsars.
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