Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time, and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space. While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes, vast areas of the tropics remain understudied. In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity, but it remains among the least known forests in America and is often underrepresented in biodiversity databases. To worsen this situation, human-induced modifications may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge, it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

Surface ferro (or antiferro) magnetism in bulk antiferro (or ferro) magnets : renormalization group analysis

The renormalization group techniques are applied, for the first time, to surface magnetism in bulk magnets, for all signs of surface and bulk coupling constants. The q-state Potts model is specifically focused upon, and an interesting q-evolution of the phase diagram is exhibited. In particular the Ising model (q = 2) presents a remarkable feature in the case of competing bulk-and surface interactions : surface ferro (or antiferro) magnetism can disappear while heating an antiferro (or ferro) magnet, and reappear again for higher temperatures, before the system enters in the paramagnetic phase.Les techniques de groupe de renormalisation dans l'espace réel sont appliquées pour la première fois au magnétisme de surface de systèmes magnétiques, pour tous les signes des constantes de couplage de surface et de volume. En particulier, nous nous sommes int6ress6s au modèle de Potts à q états et nous exhibons une intéressante variation du diagramme de phase en fonction de la valeur de q. Ainsi dans le cas du modèle d'Ising (q = 2), un phénomène remarquable apparaît dans le cas d'interactions de surface et de volume de signe opposé : l'ordre de surface ferromagnétique (ou antiferromagnétique) peut disparaître quand on augmente la température d'un système antiferromagnétique (ou ferromagnétique) dans le volume, puis réapparaître avant que le système ne devienne paramagnétique

MICROPROPAGAÇÃO DE CLONES DE BANANA cv. TERRA EM BIORREATOR DE IMERSÃO TEMPORÁRIA MICROPROPAGATION OF BANANA TERRA USING TEMPORARY IMMERSION BIOREACTORS

Mudas micropropagadas de banana têm sido ofertadas ao mercado com o intuito de suprir a demanda de uma fruticultura cada vez mais tecnificada. Os preços mais elevados deste tipo de muda têm sido um dos maiores entraves ao seu uso. Vários são os fatores que oneram o seu preço final: mão-de-obra especializada, necessidade de laboratórios bem equipados, estrutura de aclimatização apropriada, baixa taxa de multiplicação de algumas variedades, etc. O presente trabalho relata a micropropagação de bananeiras cv. Terra, utilizando biorreatores de imersão temporária, com o objetivo de aumentar a taxa de multiplicação e diminuir os custos de produção das mudas. Os resultados obtidos mostraram que o ciclo de imersão de 4 horas e a renovação do meio de cultura aos 30 dias foram essenciais para uma maior produção de biomassa e crescimento dos explantes. A composição do meio de cultura influenciou o desenvolvimento dos explantes de banana cultivados nos biorreatores. Explantes cultivados em meio MS + 3mg/L de BAP com renovação para MS básico, após 30 dias, apresentaram maior produção de biomassa e alta taxa de multiplicação. Comparando-se o biorreator de imersão temporária com o sistema tradicional em semi-sólido, observou-se que, no primeiro, as microplantas apresentaram maior comprimento, produção de biomassa de 2,86 vezes maior e 2,20 vezes mais brotos do que no sistema tradicional.<br>Banana seedlings has been micropropagated and sold to the producers to supply a rather competitive fruit crop market. This high quality propagule has usually a higher price in the market than field propagated seedlings. Several factors contribute to its final costs: need of specialized labour, need of well equipped laboratory and acclimatization structure, low multiplication rate of some varieties etc. The work presented here reports the development of a new way to micropropagate banana var. Terra, a known slow seedling producing variety, by using a temporary immersion bioreactor. The aim of this work was to increase the multiplication rate of this variety of banana and to reduce the costs of production of the micropropagated seedlings. The results showed that the immersion cycle of 4 hours with medium culture renewed at 30 days was essential to a higher biomass and explants growth. The composition of the medium culture positively influenced the development of the banana explants cultured in the bioreactors. Cultured explants in MS medium + 3 mg/L of BAP changed to a basic MS medium after 30 days presented the higher biomass and multiplication rate of all treatments. Traditional cultivation using semi-solid media was compared to a temporary immersion system and the results showed that the temporary immersion system presented 2.86 times more biomass production and 2,20 times more viable shoots than the traditional semi-solid system

Cooperative Jahn-Teller effect in a 2D mesoscopic C

Fullerene molecules adsorbed on surfaces often show macroscopic average distortions. As charged ions C60n- are known to be Jahn-Teller (JT) active, it is suggested that these distortions could be a manifestation of cooperative JT effects (CJTE) due to interactions between neighbouring fullerene ions. In order to understand the distortion properties it is necessary to take correlations between different distortions into account. However, this can’t easily be done in the mean field approximation usually used to describe the CJTE. We therefore propose an alternative procedure to describe 2D mesoscopic islands of C60 ions in which a pseudo vector spin \hbox{$\overrightarrow{S}$} is evoked to represent degenerate JT-distorted states when the quadratic JT coupling is considered. This approach is analogous to methods used for 2D magnetic systems. We then use the differential operator technique in effective field theory within the Ising approach. We include the effects of weak surface interactions and dynamic motion between equivalent distortions via terms equivalent to anisotropy and a transverse field in magnetism respectively. For distortions to D5d symmetry, we determine single site correlations as a function of temperature, the macroscopic average distortion describing a structural phase transition, and the isothermal response function. Phase diagrams are presented for relevant cases of the system parameters