Weather on Other Worlds. IV. Hα\alpha emission and photometric variability are not correlated in L0−-T8 dwarfs

Recent photometric studies have revealed that surface spots that produce flux variations are present on virtually all L and T dwarfs. Their likely magnetic or dusty nature has been a much-debated problem, the resolution to which has been hindered by paucity of diagnostic multi-wavelength observations. To test for a correlation between magnetic activity and photometric variability, we searched for H$\alpha$ emission among eight L3$-$T2 ultra-cool dwarfs with extensive previous photometric monitoring, some of which are known to be variable at 3.6 $\mu$m or 4.5 $\mu$m. We detected H$\alpha$ only in the non-variable T2 dwarf 2MASS J12545393$-$0122474. The remaining seven objects do not show H$\alpha$ emission, even though six of them are known to vary photometrically. Combining our results with those for 86 other L and T dwarfs from the literature show that the detection rate of H$\alpha$ emission is very high (94$\%$) for spectral types between L0 and L3.5 and much smaller (20$\%$) for spectral types $\ge$L4, while the detection rate of photometric variability is approximately constant (30$\%-$55$\%$) from L0 to T8 dwarfs. We conclude that chromospheric activity, as evidenced by H$\alpha$ emission, and large-amplitude photometric variability are not correlated. Consequently, dust clouds are the dominant driver of the observed variability of ultra-cool dwarfs at spectral types at least as early as L0.Comment: 12 pages, 4 figures, accepted for publication in Ap

Resonant tunneling through protected quantum dots at phosphorene edges

We theoretically investigate phosphorene zigzag nanorribons as a platform for constriction engineering. In the presence of a constriction at the upper edge, quantum confinement of edge protected states reveals resonant tunnelling Breit-Wigner transmission peaks, if the upper edge is uncoupled to the lower edge. Coupling between edges in thin constrictions gives rise to Fano-like and anti-resonances in the transmission spectrum of the system.Comment: 8 pages,7 figure

Effects of group membership on the transmission of negative historical events

Los estudios muestran que la fuente de un rumor, o el que implica al endogrupo o exogrupo son aspectos fundamentales a tener en cuenta en cómo las personas se enfrentan a la transmisión de informa-ción. Los tres trabajos que se presentan aunando los resultados de estudios lleva-dos a cabo sobre las emociones colecti-vas, los rumores y las variables que inci-den en su transmisión, y los mecanismos de defensa de las identidades sociales, analizarán la manera en la que los miem-bros de un grupo se enfrentan con hechos negativos para este mismo endogrupo

New properties of a bioinspired pyridine benzimidazole compound as a novel differential staining agent for endoplasmic reticulum and Golgi apparatus in fluorescence live cell imaging

Indexación: Scopus.In this study, we explored new properties of the bioinspired pyridine benzimidazole compound B2 (2,4-di-tert-butyl-6-(3H-imidazo[4,5-c]pyridine-2-yl)phenol) regarding its potential use as a differential biomarker. For that, we performed 1D 1HNMR (TOCSY), UV-Vis absorption spectra in different organic solvents, voltammetry profile (including a scan-rate study), and TD-DFT calculations that including NBO analyses, to provide valuable information about B2 structure and luminescence. In our study, we found that the B2 structure is highly stable, where the presence of an intramolecular hydrogen bond (IHB) seems to have a crucial role in the stability of luminescence, and its emission can be assigned as fluorescence. In fact, we found that the relatively large Stokes Shift observed for B2 (around 175 nm) may be attributed to the stability of the B2 geometry and the strength of its IHB. On the other hand, we determined that B2 is biocompatible by cytotoxicity experiments in HeLa cells, an epithelial cell line. Furthermore, in cellular assays we found that B2 could be internalized by passive diffusion in absence of artificial permeabilization at short incubation times (15 min to 30 min). Fluorescence microscopy studies confirmed that B2 accumulates in the endoplasmic reticulum (ER) and Golgi apparatus, two organelles involved in the secretory pathway. Finally, we determined that B2 exhibited no noticeable blinking or bleaching after 1 h of continuous exposure. Thus, B2 provides a biocompatible, rapid, simple, and efficient way to fluorescently label particular organelles, producing similar results to that obtained with other well-established but more complex methods. © 2018 Llancalahuen, Fuentes, Carreño, Zúñiga, Páez-Hernández, Gacitúa, Polanco, Preite, Arratia-Pérez and Otero.https://www.frontiersin.org/articles/10.3389/fchem.2018.00345/ful

Social movements and collective behavior: an integration of meta-analysis and systematic review of social psychology studies

Background: The impact of social movements (SMs) and collective behavior (CB) supports the relevance of approaching this phenomenon from social psychology. Several systematic reviews (10) and meta-analyses (6) have been carried out in the 21st century, but there is a lack of integration. Aim: This study seeks to review the patterns of CB and corroborate the psychosocial factors that explain participation in CB and SMs, as well as the long-term psychological effects of participating in them. Method: A systematic search was carried out in the databases Web of Science, Scopus, ProQuest, ScienceDirect, Willey Online Library, EBSCO, and JSTOR for articles dated between 1969 and 2022. We searched for meta-analyses and systematic reviews that empirically evaluated social movements and collective behavior. Of the 494 initial records, after scanning and eligibility phases, 16 meta-analyses and systematic reviews were analyzed in the present work. Results: The evidence reviewed shows that participation in collective gatherings and CB are common. A cross-cultural survey suggests that collective gatherings are mostly of a leisure type, to a lesser extent religious and sporting, and to an even lesser extent, demonstrations and large religious rites. World Value surveys found that one to three persons out of 10 participate in protests or CB related to SMs and four out of 10 movements achieved some kind of success. Studies challenged that CBs were characterized by unanimity of beliefs, identification and behavior, generalized excitement, as well as mass panic and riot after catastrophes. Only two out of 10 CB are violent. Meta-analysis and systematic reviews confirm that participation in CB and SMs was associated with (a) intergroup conflict and realistic threat (r = 0.30); (b) positive attitudes, expectations, or agreement with goals or collective motive (r = 0.44); (c) cognitive fraternal relative deprivation (r = 0.25); (d) collective efficacy (r = 0.36); (e) collective identity (r = 0.34); (f) emotions and affective relative deprivation (r = 0.35); (g) moral conviction and threat to moral (r = 0.29); and (h) disagreement with system justification belief (r = −0.26). Participation in successful CB and SMs provokes positive changes in emotions, social identity and social relationships, values and beliefs, and empowerment, as well as negative effects such as depression, stress, burnout, and disempowerment related to the failures of SMs. Conclusion: Studies confirm the importance of explanatory factors for SMs, with data from various cultural regions. There is a lack of systematic studies of CB as well as meta-analyses and more culturally diverse studies of the effects of participation in them