Effect of Co substitution on the structural,dielectric and optical properties of KBiFe2O5

Cobalt (Co)-modified brownmillerite KBiFe2O5 (KBFO; [KBiFe2(1?x)Co2xO5 (x = 0, 0.05)]) polycrystalline is synthesized following the solid-state reaction route. Rietveld refinement of X-ray diffraction data confirmed the phase purity of KBFO and KBiFe1.9Co0.1O5 (KBFCO). The optical bandgap energy (Eg) of KBFO decreased from 1.59 to 1.51 eV because of Co substitution. The decrease in bandgap can be attributed to the tilting of the Fe–O tetrahedral structure of KBFCO. The observed room-temperature Raman peaks of KBFCO shifted by 3 cm?1 toward a lower wavenumber than that of KBFO. The shift in Raman active modes can be attributed to the change in the bond angles and bond lengths of the Fe–O tetrahedral structure and modification in response to oxygen deficiency in KBFO because of Co doping. Compared with that of KBFO, the frequency-dependent dielectric constant and dielectric loss of KBFCO decrease at room temperature, which is a con-sequence of the reduction in oxygen migration and modification in response to vibrational modes present in the sample.     

Maxwell's role in turning the concept of model into the methodology of modeling

This is a contribution towards a history and philosophy of modeling in its early stages in electromagnetism. In 1873, James Clerk Maxwell (1831–1879) hinted at the methodology of modeling at the end of his Treatise on Electricity and Magnetism. We focus on Maxwell's impact on physicists who immediately followed him, specifically Oliver Lodge (1851–1940) and George Francis FitzGerald (1851–1901). We begin with the role that the scientific concept of model played in the late nineteenth century, as assessed by Ludwig Boltzmann (1844–1906). We then discuss the role of hypothesis as a methodology, the appeal to (dynamical) illustration, and the way Maxwell applied model and working model in his studies of electromagnetism. We show that for Maxwell these key terms were kept distinct, but Lodge did not maintain these distinctions and, in this regard, FitzGerald followed Lodge. Notwithstanding Lodge's influence, Fitzgerald modified Maxwell's theory based on the mechanical model he designed, thereby implicitly taking the first step towards modeling. This methodology consists in drawing consequences from the (mechanical) model to the (electrodynamic) theory and modifying the latter in light of the functioning of the former. At the core of our argument is the thesis that it was a methodological novelty to move from the concept of model to the methodology of modeling. The introduction of modeling as a new methodology into physics in the late nineteenth century was a major event which deserves proper recognition.     

The futility of decision making research

We have each spent more than 50 years doing research that has had little impact. Even more lamentable is that our field, judgment and decision making (JDM), has on the whole had little impact during that span. We attribute that failure to the use of methodologies that emphasize testing models rather than looking for differences in behavior. The “cognitive revolution” led the field astray, toward the goal of studying model fit rather than comparing observable results. With modeling as the goal, experimentation was stultified. Simple tasks became dominant. Although a poor metaphor for real decision making, the gambling paradigm has lasted forever because the inputs to the decision are known to the researcher and thus easily modeled.     

Methods for backcasting,nowcasting and forecasting using factor‐MIDAS: With an application to Korean GDP

We utilize mixed‐frequency factor‐MIDAS models for the purpose of carrying out backcasting, nowcasting, and forecasting experiments using real‐time data. We also introduce a new real‐time Korean GDP dataset, which is the focus of our experiments. The methodology that we utilize involves first estimating common latent factors (i.e., diffusion indices) from 190 monthly macroeconomic and financial series using various estimation strategies. These factors are then included, along with standard variables measured at multiple different frequencies, in various factor‐MIDAS prediction models. Our key empirical findings as follows. (i) When using real‐time data, factor‐MIDAS prediction models outperform various linear benchmark models. Interestingly, the “MSFE‐best” MIDAS models contain no autoregressive (AR) lag terms when backcasting and nowcasting. AR terms only begin to play a role in “true” forecasting contexts. (ii) Models that utilize only one or two factors are “MSFE‐best” at all forecasting horizons, but not at any backcasting and nowcasting horizons. In these latter contexts, much more heavily parametrized models with many factors are preferred. (iii) Real‐time data are crucial for forecasting Korean gross domestic product, and the use of “first available” versus “most recent” data “strongly” affects model selection and performance. (iv) Recursively estimated models are almost always “MSFE‐best,” and models estimated using autoregressive interpolation dominate those estimated using other interpolation methods. (v) Factors estimated using recursive principal component estimation methods have more predictive content than those estimated using a variety of other (more sophisticated) approaches. This result is particularly prevalent for our “MSFE‐best” factor‐MIDAS models, across virtually all forecast horizons, estimation schemes, and data vintages that are analyzed.     

Is the valid species Synchaeta monopus Plate, 1889 (Rotifera: Monogononta) a product of preparation artefacts?

The morphology of soft-bodied rotifers, including those of Synchaeta spp, can be strongly affected by preparation artefacts including contraction and deformation. The long-standing, valid species Synchaeta monopus is known exclusively from ethanol- or formaldehyde-preserved material and no live specimens of it have ever been described. Although this alone is cause for concern, we could also reproduce unique characteristics diagnostic for this species (e.g. the swollen body and the rudimental foot) by subjecting specimens of Synchaeta pectinata to the preservation conditions under which it was first described. This proxy experiment and comparisons to other Synchaeta species indicate that literature occurrences of S. monopus likely represent preserved and deformed specimens of Synchaeta cecilia or other marine species of Synchaeta, thereby highlighting the importance of thorough morphological investigations of the habitus using live specimens and of features that are unaffected by preservation (e.g. the trophi). We therefore recommend that S. monopus be listed as a species inquirenda until topotypes are examined. Furthermore, in ecological studies including rotifers, where the examination of preserved material is often unavoidable, we stress that light-microscopical images of the habitus and trophi of the specimens minimally be included to facilitate independent verification of the species assignments.     

The carcinofauna found in stomach contents of the flying gurnard (Dactylopterus volitans) on the continental shelf of the Campos Basin,Brazil

A total of 3109 crustaceans belonging to 50 taxa distributed in 42 families were found in 117 analysed stomachs of flying gurnard (Dactylopterus volitans). Samples were obtained in April 2008 by the R/V Gyre using a bottom trawl towed in 12 stations at 14–100 m depth on the continental shelf of the Campos Basin, Brazil. The carcinofauna was analysed and the order Calanoida (Copepoda) found to be the most important item in terms of relative abundance and frequency of occurrence, followed by the order Amphipoda (Peracarida), the infraorder Brachyura (Decapoda), the order Stomatopoda and the subclass Myodocopa (Ostracoda). In the order Calanoida, the species Pontellopsis cf. villosa (Pontellidae) represented 98.04% of total crustacean abundance. The diet of Dactylopterus volitans varied according to fish size, with higher diversity of Crustacea at smaller size classes, decreasing in larger fishes. A similar pattern regarding depth was obtained, with greater diversity of taxa in gurnard stomachs caught at shallower depths. Flying gurnard is considered a generalized carnivore of invertebrates, eating mobile macrobenthic organisms, such as crustaceans, and its diet varies with its life stage, without any specific group as its main food source.     

Prion protein cleavage fragments regulate adult neural stem cell quiescence through redox modulation of mitochondrial fission and SOD2 expression

Neurogenesis continues in the post-developmental brain throughout life. The ability to stimulate the production of new neurones requires both quiescent and actively proliferating pools of neural stem cells (NSCs). Actively proliferating NSCs ensure that neurogenic demand can be met, whilst the quiescent pool makes certain NSC reserves do not become depleted. The processes preserving the NSC quiescent pool are only just beginning to be defined. Herein, we identify a switch between NSC proliferation and quiescence through changing intracellular redox signalling. We show that N-terminal post-translational cleavage products of the prion protein (PrP) induce a quiescent state, halting NSC cellular growth, migration, and neurite outgrowth. Quiescence is initiated by the PrP cleavage products through reducing intracellular levels of reactive oxygen species. First, inhibition of redox signalling results in increased mitochondrial fission, which rapidly signals quiescence. Thereafter, quiescence is maintained through downstream increases in the expression and activity of superoxide dismutase-2 that reduces mitochondrial superoxide. We further observe that PrP is predominantly cleaved in quiescent NSCs indicating a homeostatic role for this cascade. Our findings provide new insight into the regulation of NSC quiescence, which potentially could influence brain health throughout adult life.     

Rediscovery of Disepyris semiruber (Kieffer) (Hymenoptera: Bethylidae) in Southern Africa,with first description of the male

Holepyris semiruber Kieffer is redescribed and illustrated based on freshly collected specimens. Holepyris semiruber var. striatipleura Kieffer is considered a colour variant of this species and therefore a junior synonym of H. semiruber syn. nov. This species is transferred to Disepyris, D. semiruber (Kieffer) comb. nov., based on the possession of a short 2r-rs&Rs vein in the fore wing and presence of long flat spine-shaped setae on the outer (posterior) surface of the protarsi. The male is described for the first time from new specimens collected in South Africa. This species is recorded for the first time from Namibia and Zimbabwe. All photographs are available on www.waspweb.org.     

Revision of the Traumatomutilla juvenilis species group (Hymenoptera,Mutillidae)

ABSTRACT

Traumatomutilla duplicata duplicata (Gerstaecker, 1874), T. duplicata feia Casal, 1969, T. bruchi André, 1908, T. cristata (Gerstaecker, 1874), T. aterrima (Gerstaecker, 1874) and T. lorena (Cresson, 1902) are proposed as junior synonyms of Traumatomutilla bivittata (Gerstaecker, 1874). Traumatomutilla immaculiceps André, 1901, T. bivittata rubroguttata André, 1901 and T. estrella (Cresson, 1902) are proposed as junior synonyms of T. juvenilis (Gerstaecker, 1874). Traumatomutilla bispiculata (André, 1907) is proposed as a junior synonym of T. miniata (Gerstaecker, 1874). The previously unknown males of T. guarata Casal, 1969 and T. juvenilis are described and illustrated. All species of the T. juvenilis species group are redescribed and illustrated. A new species, Traumatomutilla juvenindica Bartholomay & Williams sp. nov., is described based on males and females from northern South America. Additionally, identification keys to the species and known colour forms of the T. juvenilis species group are provided.

http://www.zoobank.org/urn:lsid:zoobank.org:pub:3563B9EE-A45B-4939-8436-7A808D4F8996