Integer Ambiguity Resolution for Multi-GNSS and Multi-Signal Raw Phase Observations

The continuous modernisation of existing Global Navigation Satellite Systems (GNSS) and the development of new systems with a multitude of different carrier frequencies and a variety of signal modulations creates a true multi-GNSS and multi-signal environment available today. Still most precise GNSS processing strategies rely on dual-frequency measurements only by applying the Ionosphere-Free (IF) Linear Combination (LC) of GNSS observables and therefore do not benefit from the available multi-signal environment. While in this processing approach the first order effect of the ionospheric delay can be eliminated almost completely, the formation of linear combinations of GNSS observables leads to a noise increase for the resulting observations and a loss of some of the physical characteristics of the original signals, like the integer nature of the carrier phase ambiguity. In order to benefit from the multi-GNSS and multi-signal environment available today, the scientific analyses and precise applications presented in this work are based on the raw observation processing approach, which makes use of the original (raw) observations without forming any linear combinations or differences of GNSS observables. This processing strategy provides the flexibility to make use of all or a selection of available multi-GNSS and multi-signal raw observations, which are jointly processed in a single adjustment as there is no inherent limitation on the number of usable signals. The renunciation of linear combinations and observation differences preserves the physical characteristics of individual signals and implies that multi-signal biases and ionospheric delays need to be properly determined or corrected in the parameter estimation process. The raw observation processing approach is used in this work to jointly process measurements from up to three different GNSS, including eleven signals tracked on up to eight different carrier frequencies in one single adjustment. The bias handling for multi-GNSS and multi-signal applications is analysed with a focus on physically meaningful parameter estimates to demonstrate the benefits of handling clock offset parameters, multi-signal code biases and ionospheric delay estimates in a physically meaningful and consistent way. In this context, receiver-specific multi-GNSS and multisignal biases are analysed and calibrated by the use of a GNSS signal simulator. The disadvantages of eliminating physical characteristics due to the formation of linear combinations of observations or commonly used parameter estimation strategies are demonstrated and discussed. The carrier phase Integer Ambiguity Resolution (IAR) approach developed and implemented in the course of this work is based on the joint processing of multi-GNSS and multi-signal raw observations without forming any linear combinations or observation differences. Details of the implemented IAR approach are described and the performance is analysed for available carrier signal frequencies of different GNSS. Achieved results are compared to the conventional IAR approach based on IF linear combinations and the so called Widelane (WL) and Narrowlane (NL) ambiguities. In addition, the resolution of inter-system integer ambiguities is analysed for common GNSS signal frequencies. The performance of the implemented IAR approach is demonstrated and analysed by the joint Precise Orbit Determination (POD) of multi-GNSS satellites based on fixed multi-frequency carrier phase ambiguities. The improvement of the satellite orbit and clock quality by fixing raw observation ambiguities confirms the successful implementation of the IAR approach based on raw observation processing. Multi-GNSS satellite orbits and clock offsets determined with this approach are compared to results generated with the conventional IF linear combination processing approach and independent external products. This comparison demonstrates an at least equivalent performance of the implemented IAR approach based on raw observation processing. In addition, the fixed raw observation ambiguities are used to investigate and discuss characteristics of multi-GNSS and multi-frequency phase biases

Electronic structure and physical properties of the spinel-type phase of BeP2N4 from all-electron density functional calculations

Using density-functional-theory-based ab initio methods, the electronic structure and physical properties of the newly synthesized nitride BeP2N4 with a phenakite-type structure and the predicted high-pressure spinel phase of BeP2N4 are studied in detail. It is shown that both polymorphs are wide band-gap semiconductors with relatively small electron effective masses at the conduction-band minima. The spinel-type phase is more covalently bonded due to the increased number of P-N bonds for P at the octahedral sites. Calculations of mechanical properties indicate that the spinel-type polymorph is a promising superhard material with notably large bulk, shear, and Young’s moduli. Also calculated are the Be K, P K, P L3, and N K edges of the electron energy-loss near-edge structure for both phases. They show marked differences because of the different local environments of the atoms in the two crystalline polymorphs. These differences will be very useful for the experimental identification of the products of high-pressure syntheses targeting the predicted spinel-type phase of BeP2N4

Gene flow in admixed populations and implications for the conservation of the Western honeybee, Apis mellifera

Anthropogenic activity, especially modern apiculture, has considerable impact on the natural distribution of the Western honeybee, Apismellifera, leading to the spread, replacement and fragmentation of many subspecies. This creates demand for the conservation of some subspecies, in particular, Apismelliferamellifera, which once was widely distributed in Western Europe and nowadays is endangered through habitat loss and fragmentation. Moreover, A.m.mellifera may be further endangered by hybridisation in populations that now occur in artificial sympatry with other subspecies. Here, we quantify and compare individual hybridisation between sympatric and allopatric honeybee populations of A.m.mellifera and A.m.carnica using microsatellite markers and a Bayesian model-based approach. We had a special focus on pure breeding populations, which are a major tool in honeybee conservation. Our results demonstrate that subspecies are still highly differentiated, but gene flow is not prevented by the current management strategies, creating urgent demand for an improved conservation management of A.m.mellifera. However, the occurrence of a high number of pure individuals might suggest that some sort of hybrid barrier acts against the complete admixture of the two subspecie

Empirical comparison of microsatellite and SNP markers to estimate introgression in Apis mellifera mellifera

The genetic identity of the dark European honey bee, Apis mellifera mellifera is currently under pressure throughout most of its native range due to large scale commercial trade and replacement with honey bees of mainly Eastern European ancestry (C-lineage: Apis mellifera carnica and Apis mellifera ligustica). To counteract this process, numerous conservation efforts for the protection of native honey bees are sprouting across Europe. For the management of such protected areas and conservation breeding purposes, honey bee subspecies have been routinely identified through wing morphology and through DNA-hybrid tests using microsatellite markers. Currently, new methods are evolving including rapid innovations in single-nucleotide polymorphism (SNP) array technology and high-throughput sequencing. Here, we aim to quantify potential marker-specific biases of hybrid tests and give recommendations for applications in honey bee conservation management. Using an empirical dataset, we first assessed the accuracy of a recently developed reduced SNP panel to estimate C-lineage introgression in A. m. mellifera compared to whole-genome sequence (WGS) data. Using another independent data set, we estimated the differences in admixture proportions between the currently applied hybrid test based on microsatellites and the novel SNP test. We demonstrate that the SNP-based test which contains highly ancestry-informative markers is very efficient to estimate genome-wide ancestry. Furthermore, we report discrepancies between microsatellite and SNP-based admixture proportions. For conservation management, we, therefore, recommend the implementation of SNP-based hybrid tests to maintain high genetic variation within the breeding population, while minimizing influence of introduced honey bees.This work was supported by the Swiss Federal Office for Agriculture FOAG, the Fondation Sur-la-Croix, Basel, and by the 2013–2014 BiodivERsA/FACCE-JPI joint call for research proposals, with the national funders “Fundac¸ão para a Ciência e Tecnologia” (Portugal), “Agence Nationale de la Recherche” (France), and “Ministerio de Economía y Competividad” (Spain).info:eu-repo/semantics/publishedVersio

Alkaline Earth Metal Oxyhalides Revisited -Syntheses and Crystal Structures of Sr 4 OBr 6 , Ba 4 OBr 6 and Ba 2 OI 2

Single crystals of the compounds Ca 4 OCl 6 , Sr 4 OBr 6 , Ba 4 OBr 6 , and Ba 2 OI 2 were obtained by solid-state reactions. The crystals of Ba 2 OI 2 are transparent and colorless and isopointal to K 2 ZnO 2 adopting the orthorhombic space group Ibam (no. 72, Z = 4) with the cell parameters a = 747.20(9), b = 1392.02(18), and c = 678.12(9) pm. Sr 4 OBr 6 and Ba 4 OBr 6 are isotypic to Ba 4 OCl 6 (or isopointal to K 6 ZnO 4 ) and crystallize in the hexagonal space group P6 3 mc (no. 186, Z = 2) exhibiting the cell parameters a = 982.20(4) and c = 750.41(7) pm for Sr 4 OBr 6 and a = 1030.10(2) and c = 785.92(4) pm for Ba 4 OBr 6 . In the ternary systems Ca-O-X (X = Cl, Br or I) the only compound found other than the starting materials was the already known Ca 4 OCl 6 which is also isotypic to Ba 4 OCl 6 crystallizing in the hexagonal space group P6 3 mc (no. 186, Z = 2) with the cell parameters a = 903.30(6) and c = 683.27(8) pm

Genetic integrity of the Dark European honey bee (Apis mellifera mellifera) from protected populations: a genome-wide assessment using SNPs and mtDNA sequence data

The recognition that the Dark European honey bee, Apis mellifera mellifera, is increasingly threatened in its native range has led to the establishment of conservation programmes and protected areas throughout western Europe. Previous molecular surveys showed that, despite management strategies to preserve the genetic integrity of A. m. mellifera, protected populations had a measurable component of their gene pool derived from commercial C-lineage honey bees. Here we used both sequence data from the tRNAleu-cox2 intergenic mtDNA region and a genome-wide scan, with over 1183 single nucleotide polymorphisms (SNPs), to assess genetic diversity and introgression levels in several protected populations of A. m. mellifera, which were then compared with samples collected from unprotected populations. MtDNA analysis of the protected populations revealed a single colony bearing a foreign haplotype, whereas SNPs showed varying levels of introgression ranging from virtually zero in Norway to about 14% in Denmark. Introgression overall was higher in unprotected (30%) than in protected populations (8%), and is reflected in larger SNP diversity levels of the former, although opposite diversity levels were observed for mtDNA. These results suggest that, despite controlled breeding, some protected populations still require adjustments to the management strategies to further purge foreign alleles, which can be identified by SNPs.Pint

Prática de ensino supervisionada em ensino de Educação Musical no Ensino Básico

Este é o relato de experiências de ensino-aprendizagem realizadas no âmbito da Prática de Ensino Supervisionada, do Mestrado em Ensino da Educação Musical no Ensino Básico, ministrado na Escola Superior de Educação do Instituto Politécnico de Bragança. Estas experiências foram realizadas ao longo dos 1º, 2º e 3º ciclos do Ensino Básico, tendo como principal motivação a valorização da produção musical, nos domínios da composição e da interpretação, enquanto estratégia de acção capaz de contribuir para novas possibilidades de intervenção pedagógica ao nível da Educação Musical. Nos 1º e 2º ciclos, foram realizados projectos pedagógicos que cruzaram várias disciplinas artísticas e, no 3º ciclo, foi feita uma abordagem pedagógica orientada para o ensino instrumental, de forma a estreitar os espíritos do ensino “genérico” e do ensino vocacional da música. Destas experiências e abordagens pedagógicas decorreu uma reflexão crítica que pode conter elementos a ter em conta para uma discussão acerca das orientações do sistema de ensino da música em Portugal.This is the report of teaching and learning experiences occurred during the Supervised Teaching Practice, of the Master in Teaching Music Education in Primary Education, taught in the School of Education, Polytechnic Institute of Bragança. These experiences were carried out over the 1st, 2nd and 3rd cycles of basic education and to do so music production, in the fields of composition and interpretation, was the main motivation while strategy that can contribute to new possibilities of pedagogical intervention at the Musical Education level. In the 1st and 2nd cycles were conducted educational projects that intersected multiple artistic disciplines and, in the 3rd cycle, there was a pedagogical approach oriented for the instrumental teaching, in order to strengthen the spirit of the "generic" and the vocational systems of music education. These experiences and pedagogical approaches were subject of a critical reflection that can contain elements to consider for a discussion about the music education system on Portugal

Investigation of free-living honey bee colonies in Ireland

Apis mellifera mellifera (Linnaeus), the Western European honey bee, is considered extinct in the wild over most of its range due largely to hybridisation and replacement by other subspecies, parasitism by Varroa destructor, habitat loss, and effects from agricultural pesticides. The purity of the subspecies within the managed cohort is also at risk over much of its range. Here, we investigated if honey bee colonies inhabited locations outside of the apiaries. In those we located, we explored how long the colony persisted and we investigated the genotypes of the bees using multiple markers. We show here that unmanaged free-living honey bee colonies are present and widespread in Ireland, inhabiting a mixture of nesting habitats with some colonies persisting naturally and unaided over multiple years. Molecular data including mitochondrial, microsatellite, and SNPs evidence indicate that the free-living population sampled is largely comprised of pure A. m. mellifera. Finally, we discuss the implications of conserving free-living A. m. mellifera in Ireland and its possible role in improving the fitness of the managed population both in Ireland and the rest of its European range.We particularly thank the custodians of the free-living honey bee colonies and the Native Irish Honey Bee Society (NIHBS) for their assistance. KAB is a recipient of an Irish Research Council postgraduate fellowship (GOIPG/2015/2767) and a Tony Ryan Postgraduate fellowship. Additional funding was gratefully received from the Department of Agriculture, Food and the Marine [grant number GRGAS 16/GR/09], the Federation of Irish Beekeeping Associations, the Eva Crane Trust [grant number ECTA20160303] and The Native Irish Honey Bee Society. Financial support for DH was provided through the program COMPETE 2020 – POCI (Programa Operacional para a Competividade e Internacionalizac¸~ao) and by Portuguese funds through FCT (Fundac¸~ao para a Ci^encia e a Tecnologia) in the framework of the project BeeHappy (POCI-01-0145-FEDER-029871).info:eu-repo/semantics/publishedVersio

High sample throughput genotyping for estimating C-lineage introgression in the dark honeybee: an accurate and cost-effective SNP-based tool

The natural distribution of the honeybee (Apis mellifera L.) has been changed by humans in recent decades to such an extent that the formerly widest-spread European subspecies, Apis mellifera mellifera, is threatened by extinction through introgression from highly divergent commercial strains in large tracts of its range. Conservation efforts for A. m. mellifera are underway in multiple European countries requiring reliable and cost-efficient molecular tools to identify purebred colonies. Here, we developed four ancestry-informative SNP assays for high sample throughput genotyping using the iPLEX Mass Array system. Our customized assays were tested on DNA from individual and pooled, haploid and diploid honeybee samples extracted from different tissues using a diverse range of protocols. The assays had a high genotyping success rate and yielded accurate genotypes. Performance assessed against whole-genome data showed that individual assays behaved well, although the most accurate introgression estimates were obtained for the four assays combined (117 SNPs). The best compromise between accuracy and genotyping costs was achieved when combining two assays (62 SNPs). We provide a ready-to-use cost-effective tool for accurate molecular identification and estimation oinfo:eu-repo/semantics/publishedVersio