No news from old drawings? Stomach anatomy in muroid rodents in relation to body size and ecology

Muroid rodents mostly have a complex stomach: one part is lined with a cornified (nonglandular) epithelium, referred to as a “forestomach”, whereas the rest is lined with glandular epithelium. Numerous functions for the forestomach have been proposed. We collated a catalog of anatomical depictions of the stomach of 174 muroid species from which the respective nonglandular and glandular areas could be digitally measured, yielding a “stomach ratio” (nonglandular:glandular area) as a scale‐independent variable. Stomach ratios ranged from 0.13 to 20.15, and the coefficient of intraspecific variation if more than one picture was available for a species averaged at 29.7% (±21.5). We tested relationships of the ratio with body mass and various anatomical and ecological variables, including diet. There was a consistent phylogenetic signal, suggesting that closely related species share a similar anatomy. Apart from classifying stomachs into hemiglandular and discoglandular, no anatomical or ecological measure showed a consistent relationship to the stomach ratio. In particular, irrespective of statistical method or the source of dietary information, dietary proxies did not significantly correlate with the stomach ratio, except for a trend towards significance for invertivory (insectivory). Yet, even this relationship was not convincing: whereas highly insectivorous species had high but no low stomach ratios, herbivorous species had both low and high stomach ratios. Thus, the statistical effect is not due to a systematic increase in the relative forestomach size with invertivory. The most plausible hypotheses so far associate the muroid forestomach and its microbiome with a generic protective role against microbial or fungal toxins and diseases, without evident correlates of a peculiar need for this function under specific ecological conditions. Yet, this function remains to be confirmed. While providing a catalog of published depictions and hypotheses, this study highlights that the function of the muroid rodent forestomach remains enigmatic to date

Spontaneous crystal coalescence enables highly efficient perovskite solar cells

Perovskite solar cells have recently reached staggering efficiencies, through efforts focused on reducing grain boundaries, by enlarging the size of the crystalline domains that constitute the perovskite films. Here, we demonstrate that smaller crystallites within perovskite films spontaneously coalesce into larger ones, even when complete devices are stored in the dark at room temperature. We show that crystal coalescence greatly improves the performance of state of the art perovskite solar cells. Our results reveal the dynamic nature of the morphology of perovskite films and highlight the crucial role that coalescence plays in producing highly efficient device

Report of the Board of Directors to the Congress of Colombia - July 2020

In Colombia, as well as in the rest of the world, the Covid-19 pandemic has seriously damaged the health and well-being of the people. In order to limit the damage, local and national authorities have had to order large sectors of the population to be confined at their homes for long periods of time. An inevitable consequence of isolation has been the collapse of economic activity, expenditure, and employment, a phenomenon that has hit many countries of the world affected by the disease. It is an unprecedented crisis in modern times, not so much for its intensity (which is undoubtedly immense), but because its origin is not economic. That is what makes it so unpredictable and difficult to manage. Naturally, its economic consequences are enormous. Governments and central banks from all over the world are struggling to mitigate them, but the final solution is not in the hands of the economic authorities. Only science can provide a way out. In the meantime, the economic indicators in Colombia and in the rest of the world cause concern. The output falls, the massive loss of jobs, and the closure of businesses of all sizes have become daily news. Added to this, there is the deterioration in global financial conditions and the increase in the risk indicators. Financial volatility has increased and stock indexes have fallen. In the face of the lower global demand, export prices of raw materials have fallen, affecting the terms of trade for producing countries. Workers’ remittances have declined due to the increase of unemployment in developed countries. This crisis has also generated a strong reduction of global trade of goods and services, and effects on the global value chains. Central banks around the world have reacted decisively and quickly with strong liquidity injections and significant cuts to their interest rates. By mid-July, such determined response had succeeded to revert much of the initial deterioration in global financial conditions. The stock exchanges stopped their fall, and showed significant recovery in several countries. Risk premia, which at the beginning of the crisis took an unusual leap, recorded substantial corrections. Something similar happened with the volatility indexes of global financial markets, which exhibited significant improvement. Flexibilization of confinement measures in some economies, broad global liquidity, and fiscal policy measures have also contributed to improve global external financial conditions, albeit with indicators that still do not return to their pre-Covid levels

FILOSOFIA POLITICA: OS REFLEXOS DO TRABALHO NA VIDA DO HOMEM E NA JUSTIÇA SOCIAL

A Filosofia Política tem por objetivo a conceituação da justiça na sociedade. Portanto, é necessário entender o significado de justiça que cada organização tem, analisando se existe desigualdade na mesma. Assim podemos considerar se é uma sociedade justa ou não. O papel que o cidadão desenvolve também é importante, pois retrata o reflexo da atual sociedade. Assim, considera-se essencial a conciliação do tema em discussão com a obra de Hannah Arendt, “A Condição Humana”, tendo como finalidade a reflexão sobre a atual situação da sociedade sob a influência do trabalho na vida do homem.Palavras-chave: Justiça social. Condição humana. Labor. Faber. Ação

No news from old drawings? Stomach anatomy in muroid rodents in relation to body size and ecology

Muroid rodents mostly have a complex stomach: one part is lined with a cornified (nonglandular) epithelium, referred to as a “forestomach”, whereas the rest is lined with glandular epithelium. Numerous functions for the forestomach have been proposed. We collated a catalog of anatomical depictions of the stomach of 174 muroid species from which the respective nonglandular and glandular areas could be digitally measured, yielding a “stomach ratio” (nonglandular:glandular area) as a scale-independent variable. Stomach ratios ranged from 0.13 to 20.15, and the coefficient of intraspecific variation if more than one picture was available for a species averaged at 29.7% (±21.5). We tested relationships of the ratio with body mass and various anatomical and ecological variables, including diet. There was a consistent phylogenetic signal, suggesting that closely related species share a similar anatomy. Apart from classifying stomachs into hemiglandular and discoglandular, no anatomical or ecological measure showed a consistent relationship to the stomach ratio. In particular, irrespective of statistical method or the source of dietary information, dietary proxies did not significantly correlate with the stomach ratio, except for a trend towards significance for invertivory (insectivory). Yet, even this relationship was not convincing: whereas highly insectivorous species had high but no low stomach ratios, herbivorous species had both low and high stomach ratios. Thus, the statistical effect is not due to a systematic increase in the relative forestomach size with invertivory. The most plausible hypotheses so far associate the muroid forestomach and its microbiome with a generic protective role against microbial or fungal toxins and diseases, without evident correlates of a peculiar need for this function under specific ecological conditions. Yet, this function remains to be confirmed. While providing a catalog of published depictions and hypotheses, this study highlights that the function of the muroid rodent forestomach remains enigmatic to date

Multiphase induction motor drives - a technology status review

The area of multiphase variable-speed motor drives in general and multiphase induction motor drives in particular has experienced a substantial growth since the beginning of this century. Research has been conducted worldwide and numerous interesting developments have been reported in the literature. An attempt is made to provide a detailed overview of the current state-of-the-art in this area. The elaborated aspects include advantages of multiphase induction machines, modelling of multiphase induction machines, basic vector control and direct torque control schemes and PWM control of multiphase voltage source inverters. The authors also provide a detailed survey of the control strategies for five-phase and asymmetrical six-phase induction motor drives, as well as an overview of the approaches to the design of fault tolerant strategies for post-fault drive operation, and a discussion of multiphase multi-motor drives with single inverter supply. Experimental results, collected from various multiphase induction motor drive laboratory rigs, are also included to facilitate the understanding of the drive operatio

Migration of cations induces reversible performance losses over day/night cycling in perovskite solar cells

Perovskites have been demonstrated in solar cells with a power conversion efficiency of well above 20​%, which makes them one of the strongest contenders for next generation photovoltaics. While there are no concerns about their efficiency, very little is known about their stability under illumination and load. Ionic defects and their migration in the perovskite crystal lattice are some of the most alarming sources of degrdn., which can potentially prevent the commercialization of perovskite solar cells (PSCs)​. In this work, we provide direct evidence of elec. field-​induced ionic defect migration and we isolate their effect on the long-​term performance of state-​of-​the-​art devices. Supported by modeling, we demonstrate that ionic defects, migrating on timescales significantly longer (above 103 s) than what has so far been explored (from 10-​1 to 102 s)​, abate the initial efficiency by 10-​15​% after several hours of operation at the max. power point. Though these losses are not negligible, we prove that the initial efficiency is fully recovered when leaving the device in the dark for a comparable amt. of time. We verified this behavior over several cycles resembling day​/night phases, thus probing the stability of PSCs under native working conditions. This unusual behavior reveals that research and industrial stds. currently in use to assess the performance and the stability of solar cells need to be adjusted for PSCs. Our work paves the way for much needed new testing protocols and figures of merit specifically designed for PSCs

Ionic Liquid Control Crystal Growth to Enhance Planar Perovskite Solar Cells Efficiency

Ionic liquids can retard the perovskite crystallization with the aim to form compact films with larger and more uniformly distributed grain size. The ionic liquid driven crystallization is exploited to prepared a record planar perovskite solar cell with stabilized power output of 19.5%