The Clumping Transition in Niche Competition: a Robust Critical Phenomenon

We show analytically and numerically that the appearance of lumps and gaps in the distribution of n competing species along a niche axis is a robust phenomenon whenever the finiteness of the niche space is taken into account. In this case depending if the niche width of the species $\sigma$ is above or below a threshold $\sigma_c$, which for large n coincides with 2/n, there are two different regimes. For $\sigma > sigma_c$ the lumpy pattern emerges directly from the dominant eigenvector of the competition matrix because its corresponding eigenvalue becomes negative. For $\sigma </- sigma_c$ the lumpy pattern disappears. Furthermore, this clumping transition exhibits critical slowing down as $\sigma$ is approached from above. We also find that the number of lumps of species vs. $\sigma$ displays a stair-step structure. The positions of these steps are distributed according to a power-law. It is thus straightforward to predict the number of groups that can be packed along a niche axis and it coincides with field measurements for a wide range of the model parameters.Comment: 16 pages, 7 figures; http://iopscience.iop.org/1742-5468/2010/05/P0500

Caratterizzazione microstrutturale di nummi ufficiali e imitativi del V secolo d.C.

La riforma di Costantino del 309 d.C. introdusse il sistema monetario basato sulla moneta d’oro, con la qualecoesistevano, però, anche nominali d’argento e in leghe di rame: questi ultimi, denominati nummi, subironotra la fine del IV e il V secolo d. C. una netta riduzione ponderale in seguito alla quale raggiunsero pesi ancheinferiori al grammo. Nel presente lavoro sono stati caratterizzati un gruppo di nummi “bronzei” allo scopo dideterminarne la composizione chimica e la struttura metallurgica da correlare alla tecnologia di produzione.Sono state applicate tecniche microscopiche (SEM-EDS) su sezioni metallografiche e spettroscopiche (XRF) sucampioni integri. I dati ottenuti con le diverse tecniche evidenziano che le monete in bronzo, con alti tenori diPb, sono state prodotte per deformazione plastica di tondelli ottenuti per fusione entro matrici refrattarie.I valori percentuali delle componenti della lega Cu-Sn, con aggiunte di Pb, rientrano nell’intervallo dicomposizione di monete bronzee tardoantiche di ambito occidentale

BEACH AND SURFZONE MORPHODYNAMICS OS CASSINO BEACH, RS USING VIDEO IMAGERY TECHNIQUES AND BEACH PROFILES

Um experimento interdisciplinar de processos costeiros foi conduzido na Praia do Cassino, Rio Grande do Sul entre os meses de Abril e Junho de 2005. Resultados obtidos a partirde 71 perfis praiais amostrados diariamente, simultaneamente a aquisição de vídeo-imagens Argus e dados hidrodinâmicos indicam baixa e alta variação do envelope praial, associadas respectivamente às porções subaéreas e subaquosas da praia. As altas variações na porção subaquosa ocorreram em função da migração dos bancos arenosos na zona de surfe. Um deslocamento de 15 m da berma em direção à costa foi observado durante uma forte tempestade onde a altura significativa das ondas atingiu 3 m e uma alta sobre-elevação do nível do mar ocorreu em resposta a uma maré meteorológica. Três bancos arenosos foram identificados ao longo dos perfis. O primeiro, localizado próximo à linha d’água caracterizou-se como um banco inter-mareal, periodicamente exposto devido a marés meteorológicas negativas, enquanto os outros dois foram identificados em posições médias de 99 e 237 m a partir da posição média da linha d’água. Alta mobilidade em escalas temporais curtas (horas) foi observada para as posições do primeiro banco, sendo estas posições aparentemente condicionadas ao espraiamento das ondas na face praial. O segundo banco mostrou-se mais estável em curtas escalas temporais, entretanto alta mobilidade foi identificada em escalas temporais de dias. Taxas de migração em direção mar afora de até 11,6 m/dia foram medidas para o segundo banco, estando este valor associado à presença de uma corrente de retorno observada no local. Em direção à costa, contudo, valores de até 9,3 m/dia foram obtidos, predominantemente em condições de baixa dinâmica com altura significativa das ondas entre 0,5 e 0,75 m. Durante um período de 13 dias consecutivos com baixa hidrodinâmica, o segundo banco deslocou-se 45,5 m em direção à costa na região amostrada pelos perfis, agregando-se ao primeiro e caracterizando o desenvolvimento de uma feição rítmica na zona de surfe. Alta dissipação de energia das ondas associou-se ao período quando os bancos estavam agregados.During April and June of 2005, a major nearshore processes experiment was conducted at Cassino beach, RS, Brazil. Temporal changes obtained by 71 daily beach profile surveys, simultaneously with an Argus video imaging database and hydrodynamic data indicated that low and high beach mobility displayed by the beach profile envelope were respectively associated with the subaerial and subaqueous portion of the beach, being the latter caused by bar migration. A 15 m shoreward berm shift was observed during a storm with significant wave height of 3 m and high elevation of sea level above the mean shoreline location. Three bars were identified, being the first an inter-tidal bar, periodically exposed due to wind setup, and the other two sub-tidal bars located at average distances of 99 and 237 m from the shoreline. The first bar location was observed to have high mobility in short time scales (hours), and appears to be controlled by swash and backwash processes. The second bar is more stable in time scales of hours, but has higher mobility in time scales of days. It was observed offshore migration rates as high as 11.6 m/day for this bar, associated with the presence of a rip current over the profile location. Shoreward migration rates reached 9.3 m/day, and were linked to low dynamic conditions, with significant wave height between 0.5 m and 0.75 m. During 13 days of low hydrodynamic conditions, the second bar became attached to the inner bar after migrating 45.5 m, simultaneously to a rhythmic feature development. The whole sequence documented by the Argus station at the field site indicated high wave dissipation during the period of attached bars

Brief Communication: CATALYST - a multi-regional stakeholder think tank for fostering capacity development in disaster risk reduction and climate change adaptation

Abstract. This brief communication presents the work and objectives of the CATALYST project on "Capacity Development for Hazard Risk Reduction and Adaptation" funded by the European Commission (October 2011–September 2013). CATALYST set up a multi-regional think tank covering four regions (Central America and the Caribbean, East and West Africa, the European Mediterranean, and South and Southeast Asia), intending to strengthen capacity development for stakeholders involved in disaster risk reduction (DRR) and climate change adaptation, in the context of natural hazards. This communication concludes with a selection of recommendations for capacity development in DRR and climate change adaptation from the perspective of governance issues

Perigos E Riscos Associados A Processos Costeiros No Litoral Sul Do Brasil (RS): Uma Sintese

Some processes related to hydrodynamics, geomorphology and sediment movement represent coastal hazards and risks along the littoral of Rio Grande do Sul (RS) state in southern Brazil. The hazards imply in coastal erosion, habitat loss and environmental change. The risks are related to serious accidents including fatalities to the coastal users. Shoreface morphology, storms and washouts induce erosion at specific locations of the coastline. Storms and washouts, together with beach morphodynamics and depositional processes both aeolian and hydrodynamic embody latent risks to the physical integrity of people that live in and use this environment. Wave refraction patterns from SE to SW cause erosion in two coastal sectors at the proximities of Conceição Lighthouse and Hermenegildo Beach respectively located at the central and southernmost portion of the RS coastline. In both areas, the high number of washouts amplifies the erosion destroying foredunes and the subaerial beach. In addition, the lowlands of the barrier adjacent to small pocket lagoons in the northern littoral are more susceptible to washout erosion. Both, the refraction patterns and the washouts can be associated with two storms tracks and extra-tropical cyclones which magnify erosion and inundation of the coastal zone. The combination of higher population during summer seasons and intermediate beaches with considerable amounts of medium sand make beaches from the northern littoral and extreme south more risky for bathers. Coastline orientation in relation to the predominant NE wind causes wind-blow sand to invade the coastal plain in the form of transgressive dunes causing several hazards mainly in the northern littoral between Tramandaí and Mostardas. Short-term effects associated with episodic events of mud deposition during heavy storms on Cassino Beach influence the morphodynamics behavior on the sectors affected by the mud deposits creating coastal risks relating to beach usage.Some processes related to hydrodynamics, geomorphology and sediment movement represent coastal hazards and risks along the littoral of Rio Grande do Sul (RS) state in southern Brazil. The hazards imply in coastal erosion, habitat loss and environmental change. The risks are related to serious accidents including fatalities to the coastal users. Shoreface morphology, storms and washouts induce erosion at specific locations of the coastline. Storms and washouts, together with beach morphodynamics and depositional processes both aeolian and hydrodynamic embody latent risks to the physical integrity of people that live in and use this environment. Wave refraction patterns from SE to SW cause erosion in two coastal sectors at the proximities of Conceição Lighthouse and Hermenegildo Beach respectively located at the central and southernmost portion of the RS coastline. In both areas, the high number of washouts amplifies the erosion destroying foredunes and the subaerial beach. In addition, the lowlands of the barrier adjacent to small pocket lagoons in the northern littoral are more susceptible to washout erosion. Both, the refraction patterns and the washouts can be associated with two storms tracks and extra-tropical cyclones which magnify erosion and inundation of the coastal zone. The combination of higher population during summer seasons and intermediate beaches with considerable amounts of medium sand make beaches from the northern littoral and extreme south more risky for bathers. Coastline orientation in relation to the predominant NE wind causes wind-blow sand to invade the coastal plain in the form of transgressive dunes causing several hazards mainly in the northern littoral between Tramandaí and Mostardas. Short-term effects associated with episodic events of mud deposition during heavy storms on Cassino Beach influence the morphodynamics behavior on the sectors affected by the mud deposits creating coastal risks relating to beach usage

A Best Practices Notebook for Disaster Risk Reduction and Climate Change Adaptation: Guidance and Insights for Policy and Practice from the CATALYST Project

This publication, A Best Practices Notebook for Disaster Risk Reduction and Climate Change Adaptation: Guidance and Insights for Policy and Practice from the CATALYST Project is one of two main CATALYST knowledge products that focus on the transformative approaches and measures that can support Disaster Risk Reduction (DRR) and Climate Change Adaptation (CCA). It is complemented by the Best Practices Papers: Before Disaster Strikes – Transformations in Practice and Policy prepared for each of the four CATALYST regions (South and Southeast Asia, Mediterranean Europe, East and West Africa, and Central America and the Caribbean). While the previous publications present the practices considered by stakeholders to be among the most important in each region, this publication summarises the key results of the entire project from a multi-regional perspective. In doing so, it focuses on some of the most essential themes that have emerged from the CATALYST Think Tank over the last two years: ecosystems-based DRR/CCA; mainstreaming DRR/CCA; urban DRR; drought risk management for agriculture; climate risk insurance; small island developing states, and how the Hyogo Framework for Action should be followed up, as well as how to continue the CATALYST legacy

Building climate resilience through nature-based solutions in Europe: A review of enabling knowledge, finance and governance frameworks

The European Union (EU) has firmly positioned itself as a global leader in promoting and implementing nature-based solutions (NBS). The recently released EU Biodiversity Strategy for 2030, Strategy on Adaptation to Climate Change, and Forest Strategy - all representing key pillars of the ambitious European Green Deal (EGD) - rely on NBS to both preserve and restore ecosystem integrity and increase climate resilience. Although research and policy in Europe have advanced the conceptualization and operationalization of NBS, a much wider adoption is needed to reach the ambitious goals of the EGD and fulfil its vision of transforming into a sustainable, climate-neutral, climate resilient, fair, and prosperous EU by 2050. In this paper, we review recent EU-supported research, policy, and practices to identify critical dimensions that still need to be addressed for greater uptake of NBS. While recognising the multiple societal challenges NBS can target, we build on the key messages from the ‘5th European Climate Change Adaptation conference ECCA 2021′ and focus our analysis on NBS for climate change adaptation and disaster risk reduction. We screen a wide range of NBS cases across the EU and identify-three core challenges to implementation: the lack of a comprehensive evidence base on the effectiveness of NBS to address targeted challenges; the need for a greater involvement of the private sector in financing NBS; and opportunities for enhancing stakeholder engagement in the successful design and implementation of NBS. We take these challenges as the starting point for a broader reflection and critical discussion on the role of i) knowledge, i) finance, including investments in NBS and divestments from nature-negative projects, and iii) governance and policy frameworks to enable the uptake of NBS. We conclude by identifying options for the EU to foster the uptake of NBS in research, policy and practice

Imaging of the Inner Zone of Blast Furnaces Using MuonRadiography: The BLEMAB Project

The aim of the BLEMAB project (BLast furnace stack density Estimation through online Muons ABsorption measurements) is the application of muon radiography techniques, to image a blast furnace’s inner zone. In particular, the goal of the study is to characterize the geometry and size of the so-called “cohesive zone”, i.e., the spatial region where the slowly downward-moving material begins to soften and melt, which plays such an important role in the performance of the blast furnace itself. Thanks to the high penetration power of natural cosmic-ray muon radiation, muon transmission radiography could be an appropriate non invasive methodology for the imaging of large high-density structures such as a blast furnace, whose linear dimensions can be up to a few tens of meters. A state-of-the-art muon tracking system is currently in development and will be installed at a blast furnace on the ArcelorMittal site in Bremen (Germany), where it will collect data for a period of various months. In this paper, the status of the project and the expectations based on preliminary simulations are presented and briefly discussed