Ŷarba y los límites del poder rustamí. La comunidad ibāḍí de Ŷarba bajo los imāmes rustamíes de Tāhert (779-909 d.C.)

This article is aimed at analyzing the medieval and modern source material dealing with the history of Djerba under the Rustamid Imāmate in an attempt to clarify the nature of both the historical and historiographical relationship between them. It will begin by discussing the available primary and secondary source material, including the historiographical challenges they present. An analysis of the textual and archeological evidence connecting the Rustamids and Djerba will follow. Next, it will attempt to synthesize the scattered bits of evidence available in the historical record in an effort to present a clearer picture of Djerba in the Rustamid period. On the basis of this textual and archeological evidence, it will be argued that Djerba was home to an ibādī community independent of the government in Tahert for the majority ‒if not all‒ of that Imāmate’s existence ‒distinguishing the island from the surrounding areas of the Djerid (in southern Tunisia), parts of Aghlabid Ifrīqiya and the Jebel Nafūsa. Furthermore, it will be shown that evidence suggests this independence was not only a political, but also a religious one.Este ensayo analiza las fuentes de origen medieval y moderno sobre la historia de Ŷarba en el Imāmato rustamí en un intento de aclarar la naturaleza de la relación histórica e historiográfica entre ellos. Se empieza por discutir las fuentes primarias y secundarias disponibles, incluyendo los retos historiográficos que plantean y se presenta a continuación un análisis de las evidencias textuales y arqueológicas que conectan a los rustamíes con Ŷarba. Se intenta después sintetizar las piezas dispersas de la evidencia disponible en el registro histórico con el fin de presentar una imagen más clara de Ŷarba durante el período rustamí. Con base en esta evidencia textual y arqueológica, se argumentará que Ŷarba era hogar de una comunidad ibādí independiente del gobierno en Tāhert durante la mayor parte (si no en su totalidad) de la existencia del Imāmato, distinguiendo así la isla de los alrededores del Ŷarid (en el sur de Túnez), partes de la Ifrīqiya Aglabí y el Ŷabal Nafūsa. Se muestra por último que la evidencia sugiere que esta independencia no era solamente política, sino religiosa

Stoichiometry of the murine γδ T cell receptor

The T cell receptor for antigen (TCR) complex is organized into two functional domains: the antigen-binding clonotypic heterodimer and the signal-transducing invariant CD3 and TCRζ chains. In most vertebrates, there are two different clonotypic heterodimers (TCRαβ and TCRγδ) that define the αβ and γδ T cell lineages, respectively. αβ- and γδTCRs also differ in their invariant chain subunit composition, in that αβTCRs contain CD3γɛ and CD3δɛ dimers, whereas γδTCRs contain only CD3γɛ dimers. This difference in subunit composition of the αβ- and γδTCRs raises the question of whether the stoichiometries of these receptor complexes are different. As the stoichiometry of the murine γδTCR has not been previously investigated, we used two quantitative immunofluorescent approaches to determine the valency of TCRγδ heterodimers and CD3γɛ dimers in surface murine γδTCR complexes. Our results support a model of murine γδTCR stoichiometry in which there are two CD3γɛ dimers for every TCRγδ heterodimer

Sudden collapse of a colloidal gel

Metastable gels formed by weakly attractive colloidal particles display a distinctive two-stage time-dependent settling behavior under their own weight. Initially a space-spanning network is formed that for a characteristic time, which we define as the lag time \taud, resists compaction. This solid-like behavior persists only for a limited time. Gels whose age \tw is greater than \taud yield and suddenly collapse. We use a combination of confocal microscopy, rheology and time-lapse video imaging to investigate both the process of sudden collapse and its microscopic origin in an refractive-index matched emulsion-polymer system. We show that the height $h$ of the gel in the early stages of collapse is well described by the surprisingly simple expression, h(\ts) = \h0 - A \ts^{3/2}, with \h0 the initial height and \ts = \tw-\taud the time counted from the instant where the gel first yields. We propose that this unexpected result arises because the colloidal network progressively builds up internal stress as a consequence of localized rearrangement events which leads ultimately to collapse as thermal equilibrium is re-established.Comment: 14 pages, 11 figures, final versio

Baseline corticosterone does not reflect iridescent plumage traits in female tree swallows

The production of high quality secondary sexual traits can be constrained by trade-offs in the allocation of energy and nutrients with other metabolic activities, and is mediated by physiological processes. In birds, the factors influencing male plumage quality have been well studied; however, factors affecting female plumage quality are poorly understood. Furthermore, it remains uncertain which physiological traits mediate the relationship between body condition and ornaments. In this three-year study of after-second-year female tree swallows (Tachycineta bicolor), we investigated (1) the relationship between baseline corticosterone near the end of the brood-rearing period (CORTBR) and feather colour characteristics (hue, saturation, brightness) the following year, and (2) the relationship between baseline corticosterone measured during incubation (CORTI) and brood rearing (CORTBR), and feather colour in the same year. To control for reproductive effort, we included reproductive parameters as covariates in all analyses. In this first study between CORT and the plumage colour characteristics of a species bearing iridescent feathers, we did not find any relationship between CORTBR and the colour of subsequently-produced feathers, nor did we find any relationship between CORT and the colour of feathers displayed during that breeding season. If CORT levels at the end of breeding carry over to influence the immediately subsequent moult period as we expect, our results generally indicate that structural plumage quality may not be as sensitive to circulating CORT levels compared to carotenoid-based colouration. Future studies, particularly those employing experimental manipulations of CORT during moult in species with iridescent traits, are necessary to fully determine the role glucocorticoids play in mediating the quality of secondary sexual characteristics

X-ray Fluorescence Analysis of Feldspars and Silicate Glass: Effects of Melting Time on Fused Bead Consistency and Volatilisation

Reproducible preparation of lithium tetraborate fused beads for XRF analysis of glass and mineral samples is of paramount importance for analytical repeatability. However, as with all glass melting processes, losses due to volatilisation must be taken into account and their effects are not negligible. Here the effects of fused bead melting time have been studied for four Certified Reference Materials (CRM’s: three feldspars, one silicate glass), in terms of their effects on analytical variability and volatilisation losses arising from fused bead preparation. At melting temperatures of 1065 °C, and for feldspar samples, fused bead melting times shorter than approximately 25 min generally gave rise to a greater deviation of the XRF-analysed composition from the certified composition. This variation might be due to incomplete fusion and/or fused bead inhomogeneity but further research is needed. In contrast, the shortest fused bead melting time for the silicate glass CRM gave an XRF-analysed composition closer to the certified values than longer melting times. This may suggest a faster rate of glass-in-glass dissolution and homogenization during fused bead preparation. For all samples, longer melting times gave rise to greater volatilisation losses (including sulphates and halides) during fusion. This was demonstrated by a linear relationship between SO3 mass loss and time1/2, as predicted by a simple diffusion-based model. Iodine volatilisation displays a more complex relationship, suggestive of diffusion plus additional mechanisms. This conclusion may have implications for vitrification of iodine-bearing radioactive wastes. Our research demonstrates that the nature of the sample material impacts on the most appropriate fusion times. For feldspars no less than ~25 min and no more than ~60 min of fusion at 1065 °C, using Li2B4O7 as the fusion medium and in the context of feldspar samples and the automatic fusion equipment used here, strikes an acceptable (albeit non-ideal) balance between the competing factors of fused bead quality, analytical consistency and mitigating volatilisation losses. Conversely, for the silicate glass sample, shorter fusion times of less than ~30 min under the same conditions provided more accurate analyses whilst limiting volatile losses

Customizable, engineered substrates for rapid screening of cellular cues

Biophysical cues robustly direct cell responses and are thus important tools for in vitro and translational biomedical applications. High throughput platforms exploring substrates with varying physical properties are therefore valuable. However, currently existing platforms are limited in throughput, the biomaterials used, the capability to segregate between different cues and the assessment of dynamic responses. Here we present a multiwell array (3x8) made of a substrate engineered to present topography or rigidity cues welded to a bottomless plate with a 96-well format. Both the patterns on the engineered substrate and the well plate format can be easily customized, permitting systematic and efficient screening of biophysical cues. To demonstrate the broad range of possible biophysical cues examinable, we designed and tested three multiwell arrays to influence cardiomyocyte, chondrocyte and osteoblast function. Using the multiwell array, we were able to measure different cell functionalities using analytical modalities such as live microscopy, qPCR and immunofluorescence. We observed that grooves (5 µm in size) induced less variation in contractile function of cardiomyocytes. Compared to unpatterned plastic, nanopillars with 127 nm height, 100 nm diameter and 300 nm pitch enhanced matrix deposition, chondrogenic gene expression and chondrogenic maintenance. High aspect ratio pillars with an elastic shear modulus of 16 kPa mimicking the matrix found in early stages of bone development improved osteogenic gene expression compared to stiff plastic. We envisage that our bespoke multiwell array will accelerate the discovery of relevant biophysical cues through improved throughput and variety

OGA Inhibition By GlcNAc-Selenazoline

The title compound, which differs from the powerful O-GlcNAcase (OGA) inhibitor GlcNAc-thiazoline only at the chalcogen atom (Se for S), is a much weaker inhibitor in a direct OGA assay. In human cells, however, the selenazoline shows comparable ability to induce hyper-O-GlcNAc-ylation, and the two show similar reduction of insulin-stimulated translocation of glucose transporter 4 in differentiated 3T3 adipocytes. (C) 2010 Elsevier Ltd. All rights reserved

Drought at a coastal wetland affects refuelling and migration strategies of shorebirds

Droughts can affect invertebrate communities in wetlands, which can have bottom-up effects on the condition and survival of top predators. Shorebirds, key predators at coastal wetlands, have experienced widespread population declines and could be negatively affected by droughts. We explored, in detail, the effects of drought on multiple aspects of shorebird stopover and migration ecology by contrasting a year with average wet/dry conditions (2016) with a year with moderate drought (2017) at a major subarctic stopover site on southbound migration. We also examined the effects of drought on shorebird body mass during stopover across 14 years (historical: 1974–1982 and present-day: 2014–2018). For the detailed comparison of two years, in the year with moderate drought we documented lower invertebrate abundance at some sites, higher prey family richness in shorebird faecal samples, lower shorebird refuelling rates, shorter stopover durations for juveniles, and, for most species, a higher probability of making a subsequent stopover in North America after departing the subarctic, compared to the year with average wet/dry conditions. In the 14-year dataset, shorebird body mass tended to be lower in drier years. We show that even short-term, moderate drought conditions can negatively affect shorebird refuelling performance at coastal wetlands, which may carry-over to affect subsequent stopover decisions. Given shorebird population declines and predicted changes in the severity and duration of droughts with climate change, researchers should prioritize a better understanding of how droughts affect shorebird refuelling performance and survival

The Toxicology Investigators Consortium 2020 Annual Report.

The Toxicology Investigators Consortium (ToxIC) Registry was established by the American College of Medical Toxicology in 2010. The registry collects data from participating sites with the agreement that all bedside and telehealth medical toxicology consultation will be entered. This eleventh annual report summarizes the Registry\u27s 2020 data and activity with its additional 6668 cases. Cases were identified for inclusion in this report by a query of the ToxIC database for any case entered from January 1 to December 31, 2020. Detailed data was collected from these cases and aggregated to provide information which included demographics, reason for medical toxicology evaluation, agent and agent class, clinical signs and symptoms, treatments and antidotes administered, mortality, and whether life support was withdrawn. Gender distribution included 50.6% cases in females, 48.4% in males, and 1.0% identifying as transgender. Non-opioid analgesics were the most commonly reported agent class, followed by opioid and antidepressant classes. Acetaminophen was once again the most common agent reported. There were 80 fatalities, comprising 1.2% of all registry cases. Major trends in demographics and exposure characteristics remained similar to past years\u27 reports. Sub-analyses were conducted to describe race and ethnicity demographics and exposures in the registry, telemedicine encounters, and cases related to the COVID-19 pandemic