Firing rate homeostasis counteracts changes in stability of recurrent neural networks caused by synapse loss in Alzheimer's disease

The impairment of cognitive function in Alzheimer's is clearly correlated to synapse loss. However, the mechanisms underlying this correlation are only poorly understood. Here, we investigate how the loss of excitatory synapses in sparsely connected random networks of spiking excitatory and inhibitory neurons alters their dynamical characteristics. Beyond the effects on the network's activity statistics, we find that the loss of excitatory synapses on excitatory neurons shifts the network dynamic towards the stable regime. The decrease in sensitivity to small perturbations to time varying input can be considered as an indication of a reduction of computational capacity. A full recovery of the network performance can be achieved by firing rate homeostasis, here implemented by an up-scaling of the remaining excitatory-excitatory synapses. By analysing the stability of the linearized network dynamics, we explain how homeostasis can simultaneously maintain the network's firing rate and sensitivity to small perturbations

Nuances of Public Diplomacy: China in Chilean Op-Eds (2018-2021)

This paper explores editorials and opinion columns published in four Chilean mainstream newspapers and analyzes how China is represented within the context of Chinese economic advances in the region and the contextual narratives surrounding bilateral relations. Through a content analysis of editorials and opinion pieces of elite media between 2018 and 2021, this study allows an understanding of how China and its growing influence are perceived locally. Ultimately, despite an overall alignment with China’s public diplomacy centered around an economic-commercial dimension, there are still nuances in how China is represented in Chilean op-eds

Oral purified bacterial extracts in acute respiratory tract infections in childhood: a systematic quantitative review

Background: Recurrent acute respiratory tract infections (ARTI) are a common problem in childhood. Some evidence suggests a benefit regarding the prevention of ARTI in children treated with the immunomodulator OM-85 BV (Bronchovaxom). Methods: We summarised the evidence on the effectiveness of the immunomodulator OM-85 BV in the prevention of ARTI in children. We searched randomised comparisons of oral purified bacterial extracts against inactive controls in children with respiratory tract diseases in nine electronic databases and reference lists of included studies. We extracted salient features of each study, calculated relative risks (RR) or weighted mean differences (WMD) and performed meta-analyses using random-effects models. Results: Thirteen studies (2,721 patients) of low to moderate quality tested OM-85 BV. Patients and outcomes differed substantially, which impeded pooling results of more than two trials. Two studies (240 patients) reporting on the number of patients with less than three infections over 6 month of follow-up in children not in day care showed a trend for benefit RR 0.82 (95% CI, 0.65-1.02). One out of two studies examining the number of children not in day care without infections over 4-6 month reported a significant RR of 0.42 (95% CI, 0.21-0.82) whereas the smaller, second study did not [RR 0.92 (95% CI, 0.58-1.46)]. Two studies reporting the number of antibiotic courses indicated a benefit for the intervention arm [WMD 2.0 (95% CI, 1.7-2.3)]. Two out of the three studies showed a reduction of length of episodes of 4-6 days whereas a third study showed no difference between the two groups. Conclusion: Evidence in favour of OM-85 BV in the prevention of ARTI in children is weak. There is a trend for fewer and shorter infections and a reduction of antibiotic us

Monitoring air pollution close to a cement plant and in a multi-source industrial area through tree-ring analysis

Thirty-two trace elements were examined in the tree rings of downy oak to evaluate the pollution levels close to a cement plant isolated in a rural context and an industrial area where multiple sources of air pollution are or were present. Tree cores were collected from trees growing 1 km from both the cement plant and the industrial area that are located 8 km from each other. The analysis of the trace elements was performed on annual tree rings from 1990 to 2016 using laser ablation inductively coupled plasma mass spectrometry. Trace elements Cs, Mg, Mn, S and Zn reflected the emission history of the cement plant. Their values have increased since early 2000s, when the cement plant started its activity. However, the lack of significant trends of pollutants in the tree rings from the industrial area and the possible effect of translocation and volatility of some elements left open questions. The very weak changes of the other trace elements in the period 1990–2016 suggest those elements do not mark any additional effect of the industrial activity on the background pollution. The results confirm that downy oak trees growing close to isolated industrial plants must be considered a pollution forest archive accessible through dendrochemistry

e-Bologna Teil 1 - Die Perspektive der Lehrentwicklung

Teil 1 des Themenheftes "E-Bologna" trägt unter der Perspektive der Lehrent­wick­lung Projektbeispiele zusammen, in denen implizit oder explizit der Einsatz digitaler Medien zur Umsetzung dieser Bologna-Richtlinien beiträgt. Implizit, wenn solche Szenarien unabhängig und vor der Umsetzung des Bologna-Prozesses entwickelt wurden und damit aufgrund erster Erfahrungen einen wertvollen Beitrag zum Bologna Prozess beitragen. Explizit, wenn die Bologna-Reform den Anstoß zur Nutzung digitaler Medien bei der Einführung von Bachelor- und Master­studiengänge gegeben hat, oder sogar notwendiges Werkzeug dafür ist. Die vorgestellten Beiträge adressieren unterschiedliche didaktische Handlungs­ebenen und reichen von Ansätzen zur Strukturierung von Wissensmedien bis hin zur Gestaltung ganzer Studiengänge. Sie fokussieren und vertiefen verschiedene Bologna-Richtlinien, von der Modularisierung, über die Schlüsselqualifikationen bis hin zur Mobilität. Eines haben die Beiträge gemeinsam: die neuen Medien und E-Learning sind immer Werkzeug für die integrative Lehrentwicklung, d.h. für die Qualitäts­ent­wicklung und nicht für die Addition zusätzlicher Angebote zum bereits Bestehenden. 25.02.2007 | Gudrun BACHMANN, Claudia BREMER & Doris CARSTENSE

Atomic layer deposition for efficient oxygen evolution reaction at Pt/Ir catalyst layers

We provide a direct comparison of two distinct methods of Ti felt surface treatment and Pt/Ir electrocatalyst deposition for the positive electrode of regenerative fuel cells and vanadium-air redox flow batteries. Each method is well documented in the literature, and this paper provides a direct comparison under identical experimental conditions of electrochemical measurements and in identical units. In the first method, based on classical engineering, the bimetallic catalyst is deposited by dip-coating in a precursor solution of the salts followed by their thermal decomposition. In the alternative method, more academic in nature, atomic layer deposition (ALD) is applied to the felts after anodization. ALD allows for a controlled coating with ultralow noble-metal loadings in narrow pores. In acidic electrolyte, the ALD approach yields improved mass activity (557 A·g-1 as compared to 80 A·g-1 at 0.39 V overpotential) on the basis of the noble-metal loading, as well as improved stability. © 2020 Schlicht et al

Medios de comunicación y confianza política en América Latina: análisis individual y contextual del rol de las noticias en la confianza en el gobierno y el Estado

What is the relationship between news exposure and political trust in Latin America? Does this relationship change according to freedom levels of media systems and degrees of political polarization? To answer these questions, this study analyzes data from 10 Latin American countries included in the last round of the World Values Survey (2017-2020) (N = 11,769), as well as indices of governments’ intervention in the news system and polarization by the V-Dem project. Statistical results show that, in general, exposure to news on social media is negatively related to trust in government and state institutions. However, context makes a significant difference: the higher the level of media freedom and polarization, the more negative this relationship becomes. In contrast, traditional media news use is positively associated with political trust, regardless of contextual factors. This confirms the importance of considering micro and macro news media contexts when analyzing trust in Latin America.¿Cuál es la asociación entre exposición a noticias y confianza política en Latinoamérica? ¿Hay diferencias según la libertad del sistema de medios y los niveles de polarización política? Para responder estas preguntas, este estudio analiza 10 países latinoamericanos incluidos en la última Encuesta Mundial de Valores (2017-2020) (N = 11.769), así como los índices de intervención gubernamental en el sistema informativo y polarización del proyecto V-Dem. Los resultados estadísticos muestran que, en general, la exposición a noticias en plataformas sociales se relaciona negativamente con la confianza en instituciones del gobierno y el Estado. Sin embargo, el contexto hace una diferencia significativa: a mayor libertad de información y polarización, más negativa es esta relación. En cambio, el uso de los medios tradicionales se asocia positivamente con la confianza política, independientemente de los factores contextuales. Estos hallazgos confirman la importancia de considerar el contexto mediático micro y macro en el análisis sobre confianza en América Latina

On the origin of the widespread self-compatible allotetraploid Capsella bursa-pastoris (Brassicaceae)

Polyploidy, or whole-genome duplication, is a common speciation mechanism in plants. An important barrier to polyploid establishment is a lack of compatible mates. Because self-compatibility alleviates this problem, it has long been hypothesized that there should be an association between polyploidy and self-compatibility (SC), but empirical support for this prediction is mixed. Here, we investigate whether the molecular makeup of the Brassicaceae self-incompatibility (SI) system, and specifically dominance relationships among S-haplotypes mediated by small RNAs, could facilitate loss of SI in allopolyploid crucifers. We focus on the allotetraploid species Capsella bursa-pastoris, which formed similar to 300 kya by hybridization and whole-genome duplication involving progenitors from the lineages of Capsella orientalis and Capsella grandiflora. We conduct targeted long-read sequencing to assemble and analyze eight full-length S-locus haplotypes, representing both homeologous subgenomes of C. bursa-pastoris. We further analyze small RNA (sRNA) sequencing data from flower buds to identify candidate dominance modifiers. We find that C. orientalis-derived S-haplotypes of C. bursa-pastoris harbor truncated versions of the male SI specificity gene SCR and express a conserved sRNA-based candidate dominance modifier with a target in the C. grandiflora-derived S-haplotype. These results suggest that pollen-level dominance may have facilitated loss of SI in C. bursa-pastoris. Finally, we demonstrate that spontaneous somatic tetraploidization after a wide cross between C. orientalis and C. grandiflora can result in production of self-compatible tetraploid offspring. We discuss the implications of this finding on the mode of formation of this widespread weed

Absence of Erythrocyte Sequestration and Lack of Multicopy Gene Family Expression in Plasmodium falciparum from a Splenectomized Malaria Patient

BACKGROUND:To avoid spleen-dependent killing mechanisms parasite-infected erythrocytes (IE) of Plasmodium falciparum malaria patients have the capacity to bind to endothelial receptors. This binding also known as sequestration, is mediated by parasite proteins, which are targeted to the erythrocyte surface. Candidate proteins are those encoded by P. falciparum multicopy gene families, such as var, rif, stevor or PfMC-2TM. However, a direct in vivo proof of IE sequestration and expression of multicopy gene families is still lacking. Here, we report on the analysis of IE from a black African immigrant, who received the diagnosis of a malignant lymphoproliferative disorder and subsequently underwent splenectomy. Three weeks after surgery, the patient experienced clinical falciparum malaria with high parasitemia and circulating developmental parasite stages usually sequestered to the vascular endothelium such as late trophozoites, schizonts or immature gametocytes. METHODOLOGY/PRINCIPAL FINDINGS:Initially, when isolated from the patient, the infected erythrocytes were incapable to bind to various endothelial receptors in vitro. Moreover, the parasites failed to express the multicopy gene families var, A-type rif and stevor but expression of B-type rif and PfMC-2TM genes were detected. In the course of in vitro cultivation, the parasites started to express all investigated multicopy gene families and concomitantly developed the ability to adhere to endothelial receptors such as CD36 and ICAM-1, respectively. CONCLUSION/SIGNIFICANCE:This case strongly supports the hypothesis that parasite surface proteins such as PfEMP1, A-type RIFIN or STEVOR are involved in interactions of infected erythrocytes with endothelial receptors mediating sequestration of mature asexual and immature sexual stages of P. falciparum. In contrast, multicopy gene families coding for B-type RIFIN and PfMC-2TM proteins may not be involved in sequestration, as these genes were transcribed in infected but not sequestered erythrocytes