Cumulate causes for the low contents of sulfide-loving elements in the continental crust

Despite the economic importance of chalcophile (sulfide-loving) and siderophile (metal-loving) elements (CSEs), it is unclear how they become enriched or depleted in the continental crust, compared with the oceanic crust. This is due in part to our limited understanding of the partitioning behaviour of the CSEs. Here I compile compositional data for mid-ocean ridge basalts and subduction-related volcanic rocks. I show that the mantle-derived melts that contribute to oceanic and continental crust formation rarely avoid sulfide saturation during cooling in the crust and, on average, subduction-zone magmas fractionate sulfide at the base of the continental crust prior to ascent. Differentiation of mantle-derived melts enriches lower crustal sulfide- and silicate-bearing cumulates in some CSEs compared with the upper crust. This storage predisposes the cumulate-hosted compatible CSEs (such as Cu and Au) to be recycled back into the mantle during subduction and delamination, resulting in their low contents in the bulk continental crust and potentially contributing to the scarcity of ore deposits in the upper continental crust. By contrast, differentiation causes the upper oceanic and continental crust to become enriched in incompatible CSEs (such as W) compared with the lower oceanic and continental crust. Consequently, incompatible CSEs are predisposed to become enriched in subduction-zone magmas that contribute to continental crust formation and are less susceptible to removal from the continental crust via delamination compared with the compatible CSEs

Hybrid Simulation Safety: Limbos and Zero Crossings

Physical systems can be naturally modeled by combining continuous and discrete models. Such hybrid models may simplify the modeling task of complex system, as well as increase simulation performance. Moreover, modern simulation engines can often efficiently generate simulation traces, but how do we know that the simulation results are correct? If we detect an error, is the error in the model or in the simulation itself? This paper discusses the problem of simulation safety, with the focus on hybrid modeling and simulation. In particular, two key aspects are studied: safe zero-crossing detection and deterministic hybrid event handling. The problems and solutions are discussed and partially implemented in Modelica and Ptolemy II

Improving the robustness to input errors on touch-based self-service kiosks and transportation apps

acceptedVersio

Overdiagnosis and overtreatment of breast cancer: Overdiagnosis in randomised controlled trials of breast cancer screening

Data from randomised controlled trials of mammographic screening can be used to determine the extent of any overdiagnosis, as soon as either a time equivalent to the lead-time has elapsed after the final screen, or the control arm has been offered screening. This paper reviews those randomised trials for which breast cancer incidence data are available. In recent trials in which the control group has not been offered screening, an excess incidence of breast cancer remains after many years of follow-up. In those trials in which the control arm has been offered screening, although there is a possible shift from invasive to in situ disease, there is no evidence of overdiagnosis as a result of incident screens

MR screening for iron overload in non-transfusion dependent haemoglobin H disease

published_or_final_versio

Multiple antimicrobial resistance of Escherichia coli and Salmonella species isolated from broilers and local chickens retailed along the roadside in Zaria, Nigeria

Pathogenic Escherichia coli and Salmonella species are the causative agents of various disease complexes in poultry such as colibacillosis, fowl typhoid, pullorum disease and salmonellosis. Some strains of E. coli and Salmonella spp. have been shown to be resistant to multiple antibiotics. We carried out a bacteriological investigation on 105 cloacal swabs from local and broiler chickens retailed along the roadside in Hanwa, Zaria for the occurrence of E. coli and Salmonella spp. by isolation through culture, and identification using biochemical and serotyping techniques. Serotyping of E. coli isolates was carried out with polyvalent E. coli O157:H7 antisera while Salmonella spp. isolates were serotyped using polyvalent antisera specific for all groups and type-factor for Salmonella spp. Presumptive isolates were subjected to antimicrobial susceptibility testing using 13 panels of antibiotics for both E. coli and Salmonella spp. Results showed that the overall isolation rate of Salmonella spp. was 12 (11.4%), broiler chickens had higher isolation rate 9 (12.0%) of Salmonella than local chickens. However, the isolation rate of E. coli from local chickens 15 (50.0%) was higher compared to broilers 6 (8.0%). Also, non-E. coli O157:H7 and E. coli O157:H7 were isolated from both broilers and local chickens at a frequency of 15 (14.3%) and 6 (5.7%) respectively. The overall isolation rate of E. coli was 21 (20.0%). Multiple antibiotic resistance was observed among local and broiler chickens. However, E. coli and Salmonella species were 100% susceptible to Enrofloxacin. We therefore concluded that E. coli and Salmonella species are prevalent in the cloacae of both broiler and local chickens retailed along the roadside in Hanwa, Zaria, Nigeria and could pose serious veterinary and public health risks.Keywords: Escherichia coli, Isolation, Salmonella, Serotype, Zari

A LeVeque-type Lower Bound for Discrepancy

A sharp lower bound for discrepancy on R / Z is derived that resembles the upper bound due to LeVeque. An analogous bound is proved for discrepancy on Rk / Zk. These are discussed in the more general context of the discrepancy of probablity measures. As applications, the bounds are applied to Kronecker sequences and to a random walk on the torus

E-Portfolio Development and Implementation in Malaysian Technical and Vocational Education Training (TVET): A Mixed Methods Analysis of Stakeholders' and Students' perceptions

In line with the global increase in the use of E-portfolio technologies in learning organizations, their potential use in Malaysia is promising, especially in the growing areas of Technical and Vocational Education Training (TVET). In order to understand and evaluate the potential of E-portfolios in these education areas, the initial view of the parties related to the Skills Training Program, a sub-program in TVET should be taken into consideration. Since such an electronic learning system has never previously been deployed in any public or private training institutions in Malaysia, there is a need to ensure that it has the support of the parties concerned. Thus, the key questions for this study were to investigate whether the E-portfolio is: (1) suitable for implementation in the Malaysia Skills Training Education Program, and (2) easy, efficient and effective for students to use. This study used both qualitative and quantitative methods where data collection included E-mail based interviews with several officers in Malaysia and a survey of perceptions of E-portfolio Skills Training Students from the Kuantan District of Pahang, Malaysia. The results showed that most participants agreed that the E-portfolio is well suited to be implemented as an evaluation method or value-added to improve the IT skills of the students depending on their level of training course. Although some trainees/students warned that this system needs lots of things to be considered such as facilities, technical and emotional support as well as a sensible process, most agreed that this system should be introduced in their training institutions. Similarly, the interviewees also highlighted constraints that should be considered before execution to ensure that this system will be effectively installed and completely functional to benefit trainees, instructors as well as for the Training Institutions themselves