Reproducibility of species recognition in modern planktonic foraminifera and its implications for analyses of community structure

Applications of planktonic foraminifera in Quaternary palaeoceanographic and palaeobiological studies require consistency in species identification. Yet the degree of taxonomic consistency among the practitioners and the effects of any potential deviations on community structure metrics have never been quantitatively assessed. Here we present the results of an experiment in taxonomic consistency involving 21 researchers representing a range of experience and taxonomic schools from around the world. Participants were asked to identify the same two sets of 300 specimens from a modern subtropical North Atlantic sample, one sieved at  &gt; 125&thinsp;µm and one at  &gt;  150&thinsp;µm. The identification was carried out either on actual specimens (slide test) or their digital images (digital test). The specimens were fixed so the identifications could be directly compared. In all tests, only between one-quarter and one-eighth of the specimens achieved absolute agreement. Therefore, the identifications across the participants were used to determine a consensus ID for each specimen. Since no strict consensus ( &gt; 50&thinsp;% agreement) could be achieved for 20–30&thinsp;% of the specimens, we used a soft consensus based on the most common identification. The average percentage agreement relative to the consensus of the slide test was 77&thinsp;% in the  &gt; 150&thinsp;µm and 69&thinsp;% in the  &gt; 125&thinsp;µm test. These values were 7&thinsp;% lower for the digital analyses. We find that taxonomic consistency is enhanced when researchers have been trained within a taxonomic school and when they regularly perform community analyses. There is an almost negligible effect of taxonomic inconsistency on sea surface temperature estimates based on transfer function conversion of the census counts, indicating the temperature signal in foraminiferal assemblages is correctly represented even if only two-thirds of the assemblage is consistently identified. The same does not apply to measures of diversity and community structure within the assemblage, and here we advise caution in using compound datasets for such studies. The decrease in the level of consistency when specimens are identified from digital images is significant and species-specific, with implications for the development of training sets for automated identification systems.</p

Extreme Sensitivity of the Superconducting State in Thin Films

All non-interacting two-dimensional electronic systems are expected to exhibit an insulating ground state. This conspicuous absence of the metallic phase has been challenged only in the case of low-disorder, low density, semiconducting systems where strong interactions dominate the electronic state. Unexpectedly, over the last two decades, there have been multiple reports on the observation of a state with metallic characteristics on a variety of thin-film superconductors. To date, no theoretical explanation has been able to fully capture the existence of such a state for the large variety of superconductors exhibiting it. Here we show that for two very different thin-film superconductors, amorphous indium-oxide and a single-crystal of 2H-NbSe2, this metallic state can be eliminated by filtering external radiation. Our results show that these superconducting films are extremely sensitive to external perturbations leading to the suppression of superconductivity and the appearance of temperature independent, metallic like, transport at low temperatures. We relate the extreme sensitivity to the theoretical observation that, in two-dimensions, superconductivity is only marginally stable.Comment: 10 pages, 6 figure

Babesia microti-like en un perro inmunocompetente

La babesiosis canina es una enfermedad infecciosa de distribución mundial causada por parásitos intraeritrocitarios transmitidos por garrapatas. Si bien ha sido tradicionalmente asumido que sólo dos de las 73 especies de babesias identificadas causan enfermedad en la especie canina, Babesia canis y Babesia gibsoni, recientes publicaciones demuestran que una tercera especie (Babesia microti-like) también puede parasitar a perros. Este último parásito, genéticamente relacionado con Babesia microti, es el origen de una enfermedad endémica entre la población canina del noroeste de España. Este trabajo presenta un caso no experimental de esta forma de Babesia microti-like en un perro cocker spaniel de 9 años, sin antecedentes de inmunodeficiencia ni de esplenectomía, que se presenta en la clínica veterinaria con signos de hipertermia, hemoglobinuria, escalofríos y apatía. Una muy intensa parasitemia (24%), junto con trombopenia y una acusada anemia hemolítica regenerativa fueron los hallazgos más caractéristicos. En la extensión de sangre periférica se visualizaron múltiples merozoitos intraeritrocitarios (parasitemia de un 24%) de pequeño tamaño (1-2 um) y presentación única en cada hematíe. Cuarenta y ocho horas después del comienzo de los síntomas, y tras tratamiento específico con dipropionato de imidocarb el perro evolucionó hacia la curación

Layered Antiferromagnetism Induces Large Negative Magnetoresistance in the van der Waals Semiconductor CrSBr

The recent discovery of magnetism within the family of exfoliatable van der Waals (vdW) compounds has attracted considerable interest in these materials for both fundamental research and technological applications. However current vdW magnets are limited by their extreme sensitivity to air, low ordering temperatures, and poor charge transport properties. Here we report the magnetic and electronic properties of CrSBr, an air-stable vdW antiferromagnetic semiconductor that readily cleaves perpendicular to the stacking axis. Below its N\'{e}el temperature, $T_N = 132 \pm 1$ K, CrSBr adopts an A-type antiferromagnetic structure with each individual layer ferromagnetically ordered internally and the layers coupled antiferromagnetically along the stacking direction. Scanning tunneling spectroscopy and photoluminescence (PL) reveal that the electronic gap is $\Delta_E = 1.5 \pm 0.2$ eV with a corresponding PL peak centered at $1.25 \pm 0.07$ eV. Using magnetotransport measurements, we demonstrate strong coupling between magnetic order and transport properties in CrSBr, leading to a large negative magnetoresistance response that is unique amongst vdW materials. These findings establish CrSBr as a promising material platform for increasing the applicability of vdW magnets to the field of spin-based electronics

Effects of climate-induced changes in isoprene emissions after the eruption of Mount Pinatubo

In the 1990s the rates of increase of greenhouse gas concentrations, most notably of methane, were observed to change, for reasons that have yet to be fully determined. This period included the eruption of Mt. Pinatubo and an El Nino warm event, both of which affect biogeochemical processes, by changes in temperature, precipitation and radiation. We examine the impact of these changes in climate on global isoprene emissions and the effect these climate dependent emissions have on the hydroxy radical, OH, the dominant sink for methane. We model a reduction of isoprene emissions in the early 1990s, with a maximum decrease of 40 Tg(C)/yr in late 1992 and early 1993, a change of 9%. This reduction is caused by the cooler, drier conditions following the eruption of Mt. Pinatubo. Isoprene emissions are reduced both directly, by changes in temperature and a soil moisture dependent suppression factor, and indirectly, through reductions in the total biomass. The reduction in isoprene emissions causes increases of tropospheric OH which lead to an increased sink for methane of up to 5 Tg(CH4)/year, comparable to estimated source changes over the time period studied. There remain many uncertainties in the emission and oxidation of isoprene which may affect the exact size of this effect, but its magnitude is large enough that it should remain important