Solitary vortex couples in viscoelastic Couette flow

We report experimental observation of a localized structure, which is of a new type for dissipative systems. It appears as a solitary vortex couple ("diwhirl") in Couette flow with highly elastic polymer solutions. A unique property of the diwhirls is that they are stationary, in contrast to the usual localized wave structures in both Hamiltonian and dissipative systems which are stabilized by wave dispersion. It is also a new object in fluid dynamics - a couple of vortices that build a single entity somewhat similar to a magnetic dipole. The diwhirls arise as a result of a purely elastic instability through a hysteretic transition at negligible Reynolds numbers. It is suggested that the vortex flow is driven by the same forces that cause the Weissenberg effect. The diwhirls have a striking asymmetry between the inflow and outflow, which is also an essential feature of the suggested elastic instability mechanism.Comment: 9 pages (LaTeX), 5 Postscript figures, submitte

Elastic turbulence in curvilinear flows of polymer solutions

Following our first report (A. Groisman and V. Steinberg, \sl Nature $\bf 405$, 53 (2000)) we present an extended account of experimental observations of elasticity induced turbulence in three different systems: a swirling flow between two plates, a Couette-Taylor (CT) flow between two cylinders, and a flow in a curvilinear channel (Dean flow). All three set-ups had high ratio of width of the region available for flow to radius of curvature of the streamlines. The experiments were carried out with dilute solutions of high molecular weight polyacrylamide in concentrated sugar syrups. High polymer relaxation time and solution viscosity ensured prevalence of non-linear elastic effects over inertial non-linearity, and development of purely elastic instabilities at low Reynolds number (Re) in all three flows. Above the elastic instability threshold, flows in all three systems exhibit features of developed turbulence. Those include: (i)randomly fluctuating fluid motion excited in a broad range of spatial and temporal scales; (ii) significant increase in the rates of momentum and mass transfer (compared to those expected for a steady flow with a smooth velocity profile). Phenomenology, driving mechanisms, and parameter dependence of the elastic turbulence are compared with those of the conventional high Re hydrodynamic turbulence in Newtonian fluids.Comment: 23 pages, 26 figure

IUCN's encounter with 007: safeguarding consensus for conservation

A controversy at the 2016 IUCN World Conservation Congress on the topic of closing domestic ivory markets (the 007, or so-called James Bond, motion) has given rise to a debate on IUCN's value proposition. A cross-section of authors who are engaged in IUCN but not employed by the organization, and with diverse perspectives and opinions, here argue for the importance of safeguarding and strengthening the unique technical and convening roles of IUCN, providing examples of what has and has not worked. Recommendations for protecting and enhancing IUCN's contribution to global conservation debates and policy formulation are given

Climate change and high exposure increased costs and disruption to lives and livelihoods from flooding associated with exceptionally heavy rainfall in Central Europe

The intensity and duration of the heavy rainfall put immense pressure on civil protection. Emergency management systems across Europe had been reinforced after severe flooding over the last decades and largely worked well: despite the higher intensity and larger scale, the number of fatalities is lower than in earlier floods with 24 estimated at the time of writing, compared to e.g. 232 in 2002 when flooding affected Germany, Austria, Czechia, Romania, Slovakia, and Hungary and at least 100 in 1997 when only Germany, Poland and Czechia were hit by floods. They are also much lower than in the Western European floods in 2021 when over 200 people lost their lives. ● The heavy rainfall was caused by a Vb depression, which forms when cold polar air flows from the north over the Alps, meeting very warm air in Southern Europe. Vb depressions are rare, but usually associated with heavy rain over Central Europe. Analysing analogous weather systems in the observed record suggests that there is no robust change in the number of analogous Vb depressions since the 1950s. ● The frequency is not the only characteristic of Vb depressions that could potentially change in a warming climate, other drivers of rainfall can change and affect likelihood and intensity of the overall rainfall analysed in the remainder of this study. In today’s climate, which is 1.3°C warmer than at the beginning of the industrial period, a rainfall event of this magnitude is a very rare event expected to occur about once every 100 to 300 years. As the event is by far the heaviest ever recorded, the exact return time is difficult to estimate based on only about 100 years of observed data. We use a 100 year return-time for the rest of analysis. ● To assess if human-induced climate change influenced the heavy rainfall, we first determine if there is a trend in the observations. When looking at the regional-scale described above, the gridded observational datasets show that heavy four-day rainfall events have become about twice as likely and 10% more intense since the pre-industrial era. The estimates become more uncertain when looking at more local scales and can be quite different, and are limited in places in some of the observed data. ● To quantify the role of human-induced climate change on this increase, we analyse climate models that are able to simulate heavy rainfall in the area and combine these with the observation-based assessment. All models show an increase in intensity and likelihood as well, as expected from physical processes in a warming climate. The combined change, attributable to human-induced climate change, is roughly a doubling in likelihood and a 7% increase in intensity. The models are however not explicitly modelling convection, and new convection-permitting studies have shown that increases in precipitation may have been underestimated in lower-resolution climate models. Similarly, the gridded observations do not include the heaviest rainfall. Therefore, these results are conservative. ● Under a future warming scenario where the global temperature is 2°C higher than pre-industrial levels, climate models predict even heavier 4-day rainfall events, with a further expected increase of about 5% in rainfall intensity and a further 50% increase in likelihood compared to present day. Again, these numbers are probably too low, due to the underestimation of very heavy rainfall in available climate models. ● The areas affected by the floods, notably in sprawling urban centres along major rivers, had been identified as highly vulnerable to flooding. These regions include Nysa and Wroclaw in Poland, Bratislava in Slovakia, the eastern regions of Galati and Vaslu in România, lower Austria and Vienna, as well as Ostrava, Opava, Krnov, Jeseník and Litovel in Czechia. Infrastructure and emergency management systems built after lessons learned from previous floods have been severely tested and in many cases overwhelmed by the sheer magnitude and scale of these floods, leading to damages that are estimated to several billion Euros. ● These floods were well-forecast and the death toll is considerably lower compared to the 1997 and 2002 floods, pointing to the effectiveness of investments made in forecasting, early warning systems, and forecast-based action including evacuations, flood defences and pre-emptive water reservoir releases. However, any loss of life underscores the need for further enhancements to account for climate change in enacting flood defences at scale, and improving risk communication and emergency response plans

Notes for genera: basal clades of Fungi (including Aphelidiomycota, Basidiobolomycota, Blastocladiomycota, Calcarisporiellomycota, Caulochytriomycota, Chytridiomycota, Entomophthoromycota, Glomeromycota, Kickxellomycota, Monoblepharomycota, Mortierellomycota, Mucoromycota, Neocallimastigomycota, Olpidiomycota, Rozellomycota and Zoopagomycota)

Compared to the higher fungi (Dikarya), taxonomic and evolutionary studies on the basal clades of fungi are fewer in number. Thus, the generic boundaries and higher ranks in the basal clades of fungi are poorly known. Recent DNA based taxonomic studies have provided reliable and accurate information. It is therefore necessary to compile all available information since basal clades genera lack updated checklists or outlines. Recently, Tedersoo et al. (MycoKeys 13:1--20, 2016) accepted Aphelidiomycota and Rozellomycota in Fungal clade. Thus, we regard both these phyla as members in Kingdom Fungi. We accept 16 phyla in basal clades viz. Aphelidiomycota, Basidiobolomycota, Blastocladiomycota, Calcarisporiellomycota, Caulochytriomycota, Chytridiomycota, Entomophthoromycota, Glomeromycota, Kickxellomycota, Monoblepharomycota, Mortierellomycota, Mucoromycota, Neocallimastigomycota, Olpidiomycota, Rozellomycota and Zoopagomycota. Thus, 611 genera in 153 families, 43 orders and 18 classes are provided with details of classification, synonyms, life modes, distribution, recent literature and genomic data. Moreover, Catenariaceae Couch is proposed to be conserved, Cladochytriales Mozl.-Standr. is emended and the family Nephridiophagaceae is introduced

ATLANTIC EPIPHYTES: a data set of vascular and non-vascular epiphyte plants and lichens from the Atlantic Forest

Epiphytes are hyper-diverse and one of the frequently undervalued life forms in plant surveys and biodiversity inventories. Epiphytes of the Atlantic Forest, one of the most endangered ecosystems in the world, have high endemism and radiated recently in the Pliocene. We aimed to (1) compile an extensive Atlantic Forest data set on vascular, non-vascular plants (including hemiepiphytes), and lichen epiphyte species occurrence and abundance; (2) describe the epiphyte distribution in the Atlantic Forest, in order to indicate future sampling efforts. Our work presents the first epiphyte data set with information on abundance and occurrence of epiphyte phorophyte species. All data compiled here come from three main sources provided by the authors: published sources (comprising peer-reviewed articles, books, and theses), unpublished data, and herbarium data. We compiled a data set composed of 2,095 species, from 89,270 holo/hemiepiphyte records, in the Atlantic Forest of Brazil, Argentina, Paraguay, and Uruguay, recorded from 1824 to early 2018. Most of the records were from qualitative data (occurrence only, 88%), well distributed throughout the Atlantic Forest. For quantitative records, the most common sampling method was individual trees (71%), followed by plot sampling (19%), and transect sampling (10%). Angiosperms (81%) were the most frequently registered group, and Bromeliaceae and Orchidaceae were the families with the greatest number of records (27,272 and 21,945, respectively). Ferns and Lycophytes presented fewer records than Angiosperms, and Polypodiaceae were the most recorded family, and more concentrated in the Southern and Southeastern regions. Data on non-vascular plants and lichens were scarce, with a few disjunct records concentrated in the Northeastern region of the Atlantic Forest. For all non-vascular plant records, Lejeuneaceae, a family of liverworts, was the most recorded family. We hope that our effort to organize scattered epiphyte data help advance the knowledge of epiphyte ecology, as well as our understanding of macroecological and biogeographical patterns in the Atlantic Forest. No copyright restrictions are associated with the data set. Please cite this Ecology Data Paper if the data are used in publication and teaching events. © 2019 The Authors. Ecology © 2019 The Ecological Society of Americ