RUAG (Germany)

Malagasy frogs of the subgenus Brygoomantis in the mantellid frog genus Mantidactylus currently comprise 14 described species of mostly brown, riparian frogs. Data from DNA barcoding suggested that the diversity of this subgenus is dramatically underestimated by current taxonomy. We here provide a comprehensive revision of this subgenus. We use hybrid-enrichment based DNA barcode fishing to obtain mitochondrial DNA fragments from the name-bearing type material of 16 of the 20 available names for members of this subgenus, and integrate these into a genetic dataset consisting of 1305 individuals sampled across Madagascar. By thus assigning the nomina to genetic lineages, we can confidently establish synonyms, revalidate old names, and describe the remaining diversity. We take an integrative approach to our descriptions, drawing together genetics, morphometrics and morphology, and bioacoustics for assignment. We also provide a robust phylogenomic hypothesis for the subgenus, based on 12,818 nuclear-encoded markers (almost 10 million base pairs) for 58 representative samples, sequenced using a hybrid-enrichment bait set for amphibians. Those data suggest a division of the subgenus into eight major clades and show that morphological species complexes are often paraphyletic or polyphyletic. Lectotypes are designated for Rana betsileana Boulenger, 1882; Rana biporus Boulenger, 1889; Rana curta Boulenger, 1882; Mantidactylus ambohimitombi Boulenger, 1918; Mantidactylus tripunctatus Angel, 1930; and Rana inaudax Peracca, 1893. For several other nomina, previous authors had considered a certain syntype as holotype; this has been seen as lectotype designation by implication, which, however, is ambiguous according to the provisions of the International Code of Zoological Nomenclature. Hence, we validate a previous lectotype designation by implication for Limnodytes ulcerosus Boettger, 1880 by explicitly designating the same individual as lectotype. In one other such case, that of Mantidactylus brauni Ahl, 1929, we deviate from previous authors and designate a different specimen as lectotype. We revalidate Rana inaudax Peracca, 1893 as Mantidactylus inaudax (Peracca, 1893) bona species, and Mantidactylus tripunctatus Angel, 1930 bona species. The identities of three further species (M. ambohimitombi, M. biporus, M. tricinctus) are largely redefined based on new genetic data. By designating the lectotype of Rana aluta (MZUT An725.1) as the neotype of Mantidactylus laevis Angel, 1929 we also stabilize the latter nomen (as junior synonym of M. alutus) whose original type material is lost. Based on DNA sequences of its lectotype, we consider Mantidactylus brauni Ahl, 1929 as junior synonym of M. ulcerosus (rather than M. biporus). We formally name 20 new species and four new subspecies: M. ambohimitombi marefo ssp. nov., M. ambohimitombi miloko ssp. nov., M. mahery sp. nov., M. steinfartzi sp. nov., M. incognitus sp. nov., M. jonasi sp. nov., M. katae sp. nov., M. kortei sp. nov., M. riparius sp. nov., M. fergusoni sp. nov., M. georgei sp. nov., M. jahnarum sp. nov., M. marintsoai sp. nov., M. grubenmanni sp. nov., M. gudrunae sp. nov., M. augustini sp. nov., M. bletzae sp. nov., M. brevirostris sp. nov., M. eulenbergeri sp. nov., M. glosi sp. nov., M. stelliger sp. nov., M. manerana sp. nov., M. manerana fotaka ssp. nov., and M. manerana antsanga ssp. nov. This leaves Mantidactylus subgenus Brygoomantis with 35 described species and six subspecies (including nominate subspecies). Based on our taxonomic revision, we discuss (i) the importance of definitive assignment of historical names via archival DNA analysis; (ii) the relevance of the subspecies category to name geographic variation within species; (iii) the value of molecular characters in formal species diagnoses in taxa with substantial individual variation of morphology; (iv) the use of phylogenomic approaches for taxonomy, by confirming that some morphologically similar taxa are not each other’s closest relatives, and in several cases belong to entirely different major subclades within Brygoomantis, thus facilitating lineage diagnosis; and (v) the need to interpret genetic distances in a probabilistic framework rather than using fixed thresholds, where higher distances confer a higher likelihood of genetic incompatibilities across the genome and thus completion of speciation.

Gravity fields derived from GPS tracking of the three Swarm satellites have shown artifacts near the geomagnetic equator, where the carrier phase tracking on the L2 frequency is unable to follow rapid ionospheric path delay changes due to a limited tracking loop bandwidth of only 0.25 Hz in the early years of the mission. Based on the knowledge of the loop filter design, an analytical approach is developed to recover the original L2 signal from the observed carrier phase through inversion of the loop transfer function. Precise orbit determination and gravity field solutions are used to assess the quality of the correction. We show that the a posteriori RMS of the ionosphere-free GPS phase observations for a reduced-dynamic orbit determination can be reduced from 3 to 2 mm while keeping up to 7% more data in the outlier screening compared to uncorrected observations. We also show that artifacts in the kinematic orbit and gravity field solution near the geomagnetic equator can be substantially reduced. The analytical correction is able to mitigate the equatorial artifacts. However, the analytical correction is not as successful compared to the down-weighting of problematic GPS data used in earlier studies. In contrast to the weighting approaches, up to 9–10% more kinematic positions can be retained for the heavily disturbed month March 2015 and also stronger signals for gravity field estimation in the equatorial regions are obtained, as can be seen in the reduced error degree variances of the gravity field estimation. The presented approach may also be applied to other low earth orbit missions, provided that the GPS receivers offer a sufficiently high data rate compared to the tracking loop bandwidth, and provided that the basic loop-filter parameters are known.

Recently, additive manufacturing (AM) by laser metal deposition (LMD) has become a key technology for fabricating highly complex parts without any support structures. Compared to the well-known powder bed fusion process, LMD enhances manufacturing possibilities to overcome AM-specific challenges such as process inherent porosity, minor build rates, and limited part size. Moreover, the advantages aforementioned combined with conventional machining enable novel manufacturing approaches in various fields of applications. Within this contribution, the additive manufacturing of filigree flexure pivots using 316L-Si by means of LMD with powder is presented. Frictionless flexure pivot bearings are used in space mechanisms that require high reliability, accuracy, and technical cleanliness. As a contribution to part qualification, the manufacturing process, powder material, and fabricated specimens were investigated in a comprehensive manner. Due to its major impact on the process, the chemical powder composition was characterized in detail by energy dispersive X-ray spectroscopy (EDX) and inductively coupled plasma optical emission spectrometry (ICP-OES). Moreover, a profound characterization of the powder morphology and flowability was carried out using scanning electron microscopy (SEM) and novel rheological investigation techniques. Furthermore, quantitative image analysis, mechanical testing, laser scanning microscopy, and 3D shape measurement of manufactured specimens were conducted. As a result, the gained knowledge was applied for the AM-specific redesign of the flexure pivot. Finally, a qualified flexure pivot has been manufactured in a hybrid manner to subsequently ensure its long-term durability in a lifetime test bench.

It might seem amazing: Cutting a hole in a plate can increase the buckling strength! It is the objective of this paper to present and clarify this astounding phenomenon. In lightweight design, typically thin-walled structures are used. Therefore, buckling must be considered as a possible failure mode. One might assume that removing material, and thus, reducing stiffness must result in a reduction of the buckling strength. However, perhaps surprisingly, it can be shown that introduction of cutouts, placed appropriately, can under certain conjunctures increase buckling loads. At the same time, the structural mass is reduced. Thus, the paper presents a measure, which can be used for fulfillment of a requirement in lightweight design in a twofold manner: increase in buckling strength by reduction of mass! In addition to describing a nice theoretical peculiarity, it might be of more importance from the engineering point of view that the presented methodology may help designers of lightweight structures, e.g., for aerospace applications, to place openings, which are required for some reasons in a plate being part of the construction, at such positions, at which the plate’s buckling resistance is just slightly or not at all reduced or even increased, and to avoid placing holes in unfavorable areas. Based on the Rayleigh–Ritz method in terms of the Rayleigh quotient, criteria and procedures are derived which can be used to find beneficial positions for cutouts and such ones, at which cutouts should not be placed.

Abstract Rolling element bearings are highly stressed in the contact area. For the design of these bearings both the knowledge of the acting contact stress and material and application specific stress limits are important. Data about stress limits are typically derived from rig testing results. Besides a statistic evaluation of life tests also an X-ray diffraction analysis of tested bearing components is possible. An X-ray analysis enables the detection of structural changes during the overrolling process. This kind of analysis can also be performed on bearings after use in field. A comparison between evaluation results from rig testing and from field experience enables the possibility to check the transferability from rig testing to the use in field. Several fatigue-exposed bearing components coming from different kinds of testing, were evaluated by X-ray diffraction analysis. Also, components from aeroengine bearings after use in field are investigated. All these bearing parts are made from M50, a high-speed steel which is used in critical aeroengine bearing applications. By comparing results from rig testing with results from use in field, it can be demonstrated, that it is possible to transfer findings from rig testing to the use in field.

Writing is an important language skill that must be learned by students. However, it is a complex process that makes many students have difficulty to generate ideas or struggle with brainstorming. As the result, their composition is not coherent and unity. POWER strategy can be used to help students’ in doing the process of writing. The objective of this study was to find out whether or not there was a significant difference in writing achievement between students who were taught through POWER strategy and that of those who were not. The quasi-experimental method was used. Purposive sampling technique was used to select the sample. The written test was used as an instrument. The t-test was used to analyze the data. Based on the data, it was found that tobtained (3.511) was higher than ttable (1.966), and pvalue (0.000) was lower than αvalue (0.05) It meant that null hypothesis (Ho) was rejected and consequently the alternative hypothesis(Ha)was accepted. Hence, there was a significant difference in writing achievement between students who were taught through POWER strategy and that of those who were not