A Reconsideration of Purported Holocene Bison Bones from Northern Alaska

While bison were the most abundant large mammals in Eastern Beringia for most of the last 100 000 years, their range declined drastically at the end of the Pleistocene and through the Holocene. Research into the nature of Holocene human interactions with bison suffers from scarcity of faunal remains from most archaeological sites and poor chronological control of paleontological specimens over broad areas of Eastern Beringia. We examined the dating, context, and identification of purported bison bones spatially associated with two late prehistoric archaeological sites in northern Alaska to contribute to a better understanding of bison biogeography and the possible role of these large mammals in prehistoric economies. We confirmed the presence of two bison bones from the 17th century Kangiguksuk archaeological site (49-XBM-012) in northwestern Alaska, but radiocarbon dates older than 30 000 14C years BP for both bones demonstrate that those bison were not hunted by the site occupants. From the Lakeside site (49-KIR-275) in the central Brooks Range, a bone reported to be bison and dated to about 2400 14C years BP was shown through DNA sequencing to be moose (Alces alces). We point to a large set of dated bison specimens from Alaska’s Arctic Slope that suggests bison were locally extinct in north-central and northwestern Alaska by the beginning of the Holocene and were subsequently unavailable to human hunters in that region.Bien que le bison était le gros mammifère le plus abondant de la Béringie de l’Est pendant la plus grande partie des 100 000 dernières années, sa répartition a diminué considérablement à la fin du pléistocène et pendant l’holocène. Puisque la plupart des sites archéologiques présentent peu de restes d’animaux et que le contrôle chronologique des spécimens paléontologiques sur de grandes régions de la Béringie de l’Est laisse à désirer, cela rend difficiles les recherches portant sur la nature des interactions humaines avec le bison pendant la période de l’holocène. Nous avons examiné la datation, le contexte et l’identification des soidisant os de bison géographiquement rattachés à deux anciens sites archéologiques préhistoriques du nord de l’Alaska afin de pouvoir mieux comprendre la biogéographie du bison de même que le rôle possible de ce gros mammifère au sein des économies préhistoriques. Nous avons confirmé la présence de deux os de bison provenant du site archéologique Kangiguksuk du XVIIe siècle (49-XBM-012) dans le nord-ouest de l’Alaska, mais d’après les dates déterminées par la méthode du carbone 14 remontant à plus de 30 000 14C années BP pour les deux os, ces bisons n’ont pas été chassés par les occupants du site. Au site Lakeside (49-KIR-275) de la chaîne centrale Brooks, un os qui était censé appartenir à un bison dont la datation était d’environ 2 400 14C années BP était en fait celui d’un original, ce qui a été déterminé grâce au séquençage de l’ADN (Alces alces). Nous faisons mention d’un grand ensemble de spécimens de bisons datés et provenant du talus de l’Arctique de l’Alaska. Ces spécimens laissent supposer que les bisons avaient disparu du centre-nord et du nord-ouest de l’Alaska vers le début de l’holocène et par conséquent, ils n’étaient pas à la portée des chasseurs humains de cette région

El debate público envenenado y los límites de la regulación estatal: por una alfabetización digital ante el problema de las fake news

In addition to the deliberate efforts to distort or misinform, the unintentional errors detected by thepublic —and the suspicion that there may be others not identified— have reinforced a skeptical stanceamong the public about the alleged veracity of the news. In the era of the so-called post-truth, it isno exaggeration to say that the main concern of the social sciences after the public debate has beencompletely hampered by the spread of false news and the supposed beginning of the collapse of liberaldemocracies, has been a collective sensation of shock, indignation. and despair at the increased prevalenceof false news. This paper focuses on the phenomenon of fake news, its effects in the context ofpolitical disputes and regulatory frameworks as an alleged solution. It is intended to demonstrate thatdigital literacy appears as the most adequate solution to mitigate this problem, without affecting freedomof expression in the public discursive sphere.Además de los esfuerzos deliberados por distorsionar o desinformar, los errores involuntarios detectadospor el público —y la sospecha de que pueda haber otros no identificados— han reforzado una posturaescéptica entre el público sobre la supuesta veracidad de la noticia. En la era de la llamada posverdad,no es exagerado decir que la principal preocupación de las ciencias sociales tras el debate público seve totalmente obstaculizada por la difusión de noticias falsas y el supuesto inicio del colapso de lasdemocracias liberales, ha sido una sensación colectiva de conmoción, indignación. y desesperación antela creciente prevalencia de noticias falsas. Este artículo se centra en el fenómeno de las fake news, susefectos en el contexto de las disputas políticas y los marcos regulatorios como supuesta solución. Sepretende demostrar que la alfabetización digital aparece como la solución más adecuada para mitigar esteproblema, sin afectar la libertad de expresión en el ámbito discursivo público

On the Sensitivity of a Ground-Based Tropospheric Lidar to Aitken Mode Particles in the Upper Troposphere

Airborne observations have shown high concentrations of ultrafine aerosols in the Amazon upper troposphere (UT), which are key for replenishing the planetary boundary layer (PBL) with cloud condensation nuclei that sustain the “green ocean” clouds. Given their climatic relevance, longterm observations are needed, but aircraft measurements are only available in short-term campaigns. Alternatively, continuous observations of the aerosol vertical structure could be performed by a lidar (acronym for “light detection and ranging”) system in long-term campaigns. Here we assess whether a ground-based tropospheric lidar system could detect these ultrafine UT aerosols. To this aim, we simulated the lidar signal of a real instrument and then varied the instrument’s efficiency and the UT-particle concentration to determine under which conditions the detection is possible. Optical properties were computed with a Mie code based on the size distributions and numerical concentration profiles measured by the aircraft, and on the refractive indexes inverted from AERONET measurements. The aerosol optical depth (AOD) was retrieved by inverting the elastic lidar signal, and a statistical test was applied to evaluate the detection of the UT-aerosol layer. Our results indicate that, for the instrument we simulated, a 55-fold increase in the signal-to-noise ratio (SNR) is required for a 100% detection rate. This could be achieved by simultaneously time averaging over 30 min and spatially averaging to vertical bin lengths of 375 m, or by modifying the hardware. We repeated the analysis for under- and overestimated aerosol lidar ratio (Laer), and found that possible systematic errors did not affect the detection rate. Further studies are necessary to assess whether such longtime averages are feasible in the Amazon region (given the very high cloud cover), and to design a hardware upgrade. Although simulations and analyses here were based on a particular instrument and for the presence of new organic particles in the Amazonian upper troposphere, our methodology and results are general and applicable to other instruments and sites.Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPQ) 132402/2020-3 308682/2017-

Impact of an electrode-diaphragm gap on diffusive hydrogen crossover in alkaline water electrolysis

Hydrogen crossover limits the load range of alkaline water electrolyzers, hindering their integration with renewable energy. This study examines the impact of the electrode-diaphragm gap on crossover, focusing on diffusive transport. Both finite-gap and zero-gap designs employing the state-of-the-art Zirfon UTP Perl 500 and UTP 220 diaphragms were investigated at room temperature and with a 12 wt% KOH electrolyte. Experimental results reveal a relatively high crossover for a zero-gap configuration, which corresponds to supersaturation levels at the diaphragm-electrolyte interface of 8–80, with significant fluctuations over time and between experiments due to an imperfect zero-gap design. In contrast, a finite-gap (500 μm) has a significantly smaller crossover, corresponding to supersaturation levels of 2–4. Introducing a cathode gap strongly decreases crossover, unlike an anode gap. Our results suggest that adding a small cathode-gap can significantly decrease gas impurity, potentially increase the operating range of alkaline electrolyzers, while maintaining good efficiency.</p

De Novo Aml Exhibits Greater Microenvironment Dysregulation Compared To Aml With Myelodysplasia-related Changes

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)The interaction between the bone marrow microenvironment and malignant hematopoietic cells can result in the protection of leukemia cells from chemotherapy in both myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). We, herein, characterized the changes in cytokine expression and the function of mesenchymal stromal cells (MSC) in patients with MDS, AML with myelodysplasia-related changes (MRC), a well-recognized clinical subtype of secondary AML, and de novo AML. We observed a significant inhibitory effect of MDS-MSC on T-lymphocyte proliferation and no significant differences in any of the cytokines tested. AML-MSC inhibited T-cell proliferation only at a very low MSC/T cell ratio. When compared to the control, AML-MRC-derived MSC presented a significant increase in IL6 expression, whereas de novo AML MSC presented a significant increase in the expression levels of VEGFA, CXCL12, RPGE2, IDO, IL1 beta, IL6 and IL32, followed by a decrease in IL10 expression. Furthermore, data indicate that IL-32 regulates stromal cell proliferation, has a chemotactic potential and participates in stromal cell crosstalk with leukemia cells, which could result in chemoresistance. Our results suggest that the differences between AML-MRC and de novo AML also extend into the leukemic stem cell niche and that IL-32 can participate in the regulation of the bone marrow cytokine milieu.7Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP