Network-based dissolution

We introduce a novel graph-theoretic dissolution model which applies to a number of redistribution scenarios such as gerrymandering or work economization. The central aspect of our model is to delete some vertices and redistribute their "load" to neighboring vertices in a completely balanced way. We investigate how the underlying graph structure, the pre-knowledge about which vertices to delete, and the relation between old and new "vertex load" influence the computational complexity of the underlying easy-to-describe graph problems, thereby identifying both tractable and intractable cases

Diversity in secondary metabolites including mycotoxins from strains of aspergillus section nigri isolated from raw cashew nuts from Benin, West Africa

Open access JournalIn a previous study, raw cashew kernels were assayed for the fungal contamination focusing on strains belonging to the genus Aspergillus and on aflatoxins producers. These samples showed high contamination with Aspergillus section Nigri species and absence of aflatoxins. To investigate the diversity of secondary metabolites, including mycotoxins, the species of A. section Nigri may produce and thus threaten to contaminate the raw cashew kernels, 150 strains were isolated from cashew samples and assayed for their production of secondary metabolites using liquid chromatography high resolution mass spectrometry (LC-HRMS). Seven species of black Aspergilli were isolated based on morphological and chemical identification: A. tubingensis (44%), A. niger (32%), A. brasiliensis (10%), A. carbonarius (8.7%), A. luchuensis (2.7%), A. aculeatus (2%) and A. aculeatinus (0.7%). From these, 45 metabolites and their isomers were identified. Aurasperone and pyranonigrin A, produced by all species excluding A. aculeatus and A. aculeatinus, were most prevalent and were encountered in 146 (97.3%) and 145 (95.7%) isolates, respectively. Three mycotoxins groups were detected: fumonisins (B2 and B4) (2.7%) ochratoxin A (13.3%), and secalonic acids (2%), indicating that these mycotoxins could occur in raw cashew nuts. Thirty strains of black Aspergilli were randomly sampled for verification of species identity based on sequences of β-tubulin and calmodulin genes. Among them, 27 isolates were positive to the primers used and 11 were identified as A. niger, 7 as A. tubingensis, 6 as A. carbonarius, 2 as A. luchuensis and 1 as A. welwitschiae confirming the species names as based on morphology and chemical features. These strains clustered in 5 clades in A. section Nigri. Chemical profile clustering also showed also 5 groups confirming the species specific metabolites production

Alternating skills training and clerkships to ease the transition from preclinical to clinical training

Background: The transition from preclinical to clinical training is perceived as stressful with a high workload being the main difficulty. To ease this transition, we implemented a dual learning year, where just-in-time skills training and clerkships alternated. Aims: To examine the effect of the dual learning year on students' stress and perceptions of workload and skills level, and to compare these data with a baseline measurement from a curriculum in which skills training was provided in advance of clerkships. Method: During the first Master year, students completed four rotations in which 5 weeks of skills training and 5-week clerkships alternated. In the second clerkship week of each rotation, students (n?=?476) completed questionnaires measuring their experienced workload, perceived skills level and stress. Analysis of variance was used for trend analysis and to determine differences with the baseline measurement (n?=?83). Results: During the dual learning year, 'experienced workload' decreased (F(1,471)?=?9.408, p?<?0.01), 'perceived skills level' increased (F(1,471)?=?94.202, p?<?0.001) and stress decreased (F(1,471)?=?3.309, p?<?0.10). 'Experienced workload' was lower (F(5,553)?=?7.599, p?<?0.001) and 'perceived skills level' was comparable to the baseline measurement. Conclusions: Compared to the baseline measurement and the results of earlier studies on transition difficulties, alternating just-in-time skills training and clerkships seem to ease the transition from preclinical to clinical training

A Probabilistic Algebraic Attack on the Grain Family of Stream Ciphers

v1 to the estream call for stream cipher proposals and it also became one estream finalists in the hardware category. The output function of Grain v1 connects its 160 bits internal state divided equally between an LFSR and an NFSR, using a non-linear filter function in a complex way. Over the last years many cryptanalyst identified several weaknesses in Grain v1. As a result in 2011 the inventors modified Grain v1 and published a new version of Grain named Grain-128a which has a similar structure as Grain v1 but with a 256 bits internal state with an optional authentication is the latest version of Grain family resisting all known attacks on Grain v1. However both these ciphers are quite resistant against the classical algebraic attack due to the rapid growth of the degree of the key-stream equations in subsequent clockings caused by the NFSR. This paper presents a probabilistic algebraic attack on both these Grain versions. The basic idea of our attack is to develop separate probabilistic equations for the LFSR and the NFSR bits from each key-stream equations. Surprisingly it turns out that in case of Grain-128a our proposed equations hold with all most sure probability, which makes the sure retrieval of the LFSR bits. We also outline a technique to reduce the growth of degree of the equations involving the NFSR bits for Grain v1. Further we high light that the concept of probabilistic algebraic attack as proposed in this paper can be considered as a generic attack strategy against any stream cipher having similar structure of the output function as in case of the Grain family

The digital pen as a novel device to facilitate the feedback process

Background: To improve clinical performance assessment, checklist data should be immediately available to students to offer them detailed feedback and be stored in a database for quality assurance purposes. Aim: To introduce the digital pen as clinical performance assessment tool, report examiner satisfaction and explore the utility of generated checklist data for quality assurance purposes. Methods: The digital pen technology transmits examiners? handwritten assessments to a database and exports PDF-files to students? mailboxes. Descriptive statistical analysis of examiner satisfaction and the generated checklist data was performed. Results: The examiners were satisfied with the digital pen. Valuable data were obtained to improve objective structured clinical examination stations and rating criteria, identify training needs for future students and provide examiners with feedback on their rating skills. Conclusion: The digital pen technology is a practical device for sending completed checklists to students and providing valuable data for quality assurance purposes

Occurrence of Aspergillus section Flavi and section Nigri and aflatoxins in raw cashew kernels (Anacardiumoccidentale L.) from Benin

The objective of this study was to evaluate the presence of Aspergillus section Flavi and A. section Nigri in cashew nuts harvested in the Northern Guinea (NG) and Southern Sudanian (SS) agro-ecological zones of Benin. Also, the presence of aflatoxins was investigated. For detection of fungal contamination, a total of 100 kernels/sample (with disinfection) and 40 kernels/sample (without disinfection) were plated. Seventy samples from fourteen villages were used. Aflatoxins occurrence was analysed on 84 samples by ultra–high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). The average water content and the cashew nuts count were respectively 8.6% and 172 nuts/kg in NG and 8.7% and 174 nuts/kg in SS. Significant differences between villages in both zones were found for both water content and nuts count. In disinfected samples, strains of Aspergillus section Nigri were predominant, in NG and SS zones (90.2% and 87.2%) respectively. When non disinfected kernels were plated, A. section Nigri was predominant in both NG and SS zones, with percentages of 89.7% and 93.4%, respectively. None of the 84 nuts samples were positive for natural occurrence of aflatoxins with a detection limit of 0.05–0.2 μg/kg

Diversity in secondary metabolites including mycotoxins from strains of aspergillus section nigri isolated from raw cashew nuts from benin, west africa

PubMed ID: 27768708In a previous study, raw cashew kernels were assayed for the fungal contamination focusin on strains belonging to the genus Aspergillus and on aflatoxins producers. These sample showed high contamination with Aspergillus section Nigri species and absence o aflatoxins. To investigate the diversity of secondary metabolites, including mycotoxins, th species of A. section Nigri may produce and thus threaten to contaminate the raw cashe kernels, 150 strains were isolated from cashew samples and assayed for their productio of secondary metabolites using liquid chromatography high resolution mass spectrometr (LC-HRMS). Seven species of black Aspergilli were isolated based on morphological an chemical identification: A.Tubingensis (44%), A. niger (32%), A. brasiliensis (10%), A. carbonariu (8.7%), A. luchuensis (2.7%), A. aculeatus (2%) and A. aculeatinus (0.7%). Fro these, 45 metabolites and their isomers were identified. Aurasperone and pyranonigrin A produced by all species excluding A. aculeatus and A. aculeatinus, were most prevalen and were encountered in 146 (97.3%) and 145 (95.7%) isolates, respectively. Three mycotoxin groups were detected: fumonisins (B2 and B4) (2.7%) ochratoxin A (13.3%), an secalonic acids (2%), indicating that these mycotoxins could occur in raw cashew nuts Thirty strains of black Aspergilli were randomly sampled for verification of species identit based on sequences of ß-Tubulin and calmodulin genes. Among them, 27 isolates wer positive to the primers used and 11 were identified as A. niger, 7 as A.Tubingensis, 6 as A carbonarius, 2 as A. luchuensis and 1 as A. welwitschiae confirming the species names a based on morphology and chemical features. These strains clustered in 5 clades in A. sectio Nigri. Chemical profile clustering also showed also 5 groups confirming the speciespecific metabolites production. © 2016 Lamboni et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

Degassing the "Killer Lakes" Nyos and Monoun, Cameroon

International audienceA unique humanitarian, scientific, and technical experiment is currently taking place in a forgotten mountainous region of West Africa. The experiment is on the verge of reaching its operational stage, which consists of the eradication of a “new” natural hazard; one that is potentially devastating, but which has been known for only 20 years. The Lake Nyos catastrophe, which claimed 1800 victims in August 1986, was not unprecedented. Indeed, 2 years previously a lethal gas burst, originating from nearby Lake Monoun in the same remote area of Cameroon, killed 37 people—an odd and tragic episode that went almost unnoticed. One had never before heard of Mother Nature asphyxiating human beings and most higher animals on such a scale in a single and brief non‐volcanic event