Assessing regional-scale variability in deforestation and forest degradation rates in a tropical biodiversity hotspot

Deforestation and forest degradation are major drivers of global environmental change and tropical forests are subjected to unprecedented pressures from both.For most tropical zones, deforestation rates are averaged across entire countries,often without highlighting regional differentiation. There are also very few estimates of forest degradation, either averaged or localized for the tropics. We quantified regional and country-wide changes in deforestation and forest degradation rates for Madagascar from Landsat temporal data (in two intervals,1994–2002 and 2002–2014). To our knowledge, this is the first country-wide estimate of forest degradation for Madagascar. We also performed an intensity analysis to categorize the magnitude and speed of transitions between forest,vegetation matrix, cultivated land and exposed surface. We found significant regional heterogeneity in deforestation and forest degradation. Deforestation rates decreased annually in lowland evergreen moist forest by -0.24% and in all other vegetation zones. Forest degradation rates had annual increases in the same period in lowland evergreen moist forest (0.09%), littoral forest (0.06%)but decreased in medium altitude moist evergreen forest (-0.25%), dry deciduous forest (-0.23%) and scelrophyllous woodland (-0.61%) in the same period. Despite these regional differences, higher rates of deforestation and forest degradation were consistently driven by rapid and large-sized conversions of largely intact forest to cultivated lands and exposed surfaces, most of which occurred between 1994 and 2002. These results suggest that while targeted conservation projects may have reduced forest degradation rates in some areas (e.g.medium altitude moist evergreen forest), the drivers of land cover change remain intense in relatively neglected regions. We advocate a more balanced approach to future conservation initiatives, one recognizing that deforestation and forest degradation, particularly in tropical Africa, are often driven by region-specific conditions and therefore require conservation policies tailored for local conditions

Phase transitions in self-gravitating systems. Self-gravitating fermions and hard spheres models

We discuss the nature of phase transitions in self-gravitating systems both in the microcanonical and in the canonical ensemble. We avoid the divergence of the gravitational potential at short distances by considering the case of self-gravitating fermions and hard spheres models. Three kinds of phase transitions (of zeroth, first and second order) are evidenced. They separate a ``gaseous'' phase with a smoothly varying distribution of matter from a ``condensed'' phase with a core-halo structure. We propose a simple analytical model to describe these phase transitions. We determine the value of energy (in the microcanonical ensemble) and temperature (in the canonical ensemble) at the transition point and we study their dependance with the degeneracy parameter (for fermions) or with the size of the particles (for a hard spheres gas). Scaling laws are obtained analytically in the asymptotic limit of a small short distance cut-off. Our analytical model captures the essential physics of the problem and compares remarkably well with the full numerical solutions.Comment: Submitted to Phys. Rev. E. New material adde

Enhanced inverse bremsstrahlung heating rates in a strong laser field

Test particle studies of electron scattering on ions, in an oscillatory electromagnetic field have shown that standard theoretical assumptions of small angle collisions and phase independent orbits are incorrect for electron trajectories with drift velocities smaller than quiver velocity amplitude. This leads to significant enhancement of the electron energy gain and the inverse bremsstrahlung heating rate in strong laser fields. Nonlinear processes such as Coulomb focusing and correlated collisions of electrons being brought back to the same ion by the oscillatory field are responsible for large angle, head-on scattering processes. The statistical importance of these trajectories has been examined for mono-energetic beam-like, Maxwellian and highly anisotropic electron distribution functions. A new scaling of the inverse bremsstrahlung heating rate with drift velocity and laser intensity is discussed.Comment: 12 pages, 12 figure

Laser-Cluster-Interaction in a Nanoplasma-Model with Inclusion of Lowered Ionization Energies

The interaction of intense laser fields with silver and argon clusters is investigated theoretically using a modified nanoplasma model. Single pulse and double pulse excitations are considered. The influence of the dense cluster environment on the inner ionization processes is studied including the lowering of the ionization energies. There are considerable changes in the dynamics of the laser-cluster interaction. Especially, for silver clusters, the lowering of the ionization energies leads to increased yields of highly charged ions.Comment: 10 pages, 11 figure

Density profiles of dark matter haloes: diversity and dependence on environment

(Abridged) We study the outer density profiles of dark matter haloes predicted by a generalized secondary infall model and observed in a N-body cosmological simulation of a \Lambda CDM model. We find substantial systematic variations in shapes and concentrations of the halo profiles as well as a strong correlation of the profiles with the environment. In the N-body simulation, the average outer slope of the density profiles, \beta (\rho\propto r^{-\beta}), of isolated haloes is \approx 2.9; 68% of these haloes have values of \beta between 2.5 and 3.8. Haloes in dense environments of clusters are more concentrated and exhibit a broad distribution of \beta with values larger than for isolated haloes . Contrary to what one may expect, the haloes contained within groups and galaxy systems are less concentrated and have flatter outer density profiles than the isolated haloes. The concentration decreases with M_h, but its scatter for a given mass is substantial. The mass and circular velocity of the haloes are strongly correlated: M_h \propto V_m^{\alpha} with \alpha ~ 3.3 (isolated) and ~3.5 (haloes in clusters). For M_h=10^12M_sun the rms deviations from these relations are \Delta logM_h=0.12 and 0.18, respectively. Approximately 30% of the haloes are contained within larger haloes or have massive companions (larger than ~0.3 the mass of the current halo) within 3 virial radii. The remaining 70% of the haloes are isolated objects. The distribution of \beta as well as the concentration-mass and M_h-V_m relations for the isolated haloes agree very well with the predictions of our seminumerical approach which is based on a generalization of the secondary infall model and on the extended Press-Schechter formalism.Comment: 14 pages, 11 figures included, uses mn.sty, accepted by MNRAS. Minor modifications, new and updated reference

Fast approximate hierarchical clustering using similarity heuristics

© 2008 Kull and Vilo; licensee BioMed Central Ltd

Early detection and surveillance of SARS-CoV-2 genomic variants in wastewater using COJAC

The continuing emergence of SARS-CoV-2 variants of concern and variants of interest emphasizes the need for early detection and epidemiological surveillance of novel variants. We used genomic sequencing of 122 wastewater samples from three locations in Switzerland to monitor the local spread of B.1.1.7 (Alpha), B.1.351 (Beta) and P.1 (Gamma) variants of SARS-CoV-2 at a population level. We devised a bioinformatics method named COJAC (Co-Occurrence adJusted Analysis and Calling) that uses read pairs carrying multiple variant-specific signature mutations as a robust indicator of low-frequency variants. Application of COJAC revealed that a local outbreak of the Alpha variant in two Swiss cities was observable in wastewater up to 13 d before being first reported in clinical samples. We further confirmed the ability of COJAC to detect emerging variants early for the Delta variant by analysing an additional 1,339 wastewater samples. While sequencing data of single wastewater samples provide limited precision for the quantification of relative prevalence of a variant, we show that replicate and close-meshed longitudinal sequencing allow for robust estimation not only of the local prevalence but also of the transmission fitness advantage of any variant. We conclude that genomic sequencing and our computational analysis can provide population-level estimates of prevalence and fitness of emerging variants from wastewater samples earlier and on the basis of substantially fewer samples than from clinical samples. Our framework is being routinely used in large national projects in Switzerland and the UK

Flood Proofing Low-Income Houses in India: an Application of Climate-Sensitive Probabilistic Benefit-Cost Analysis

Poor communities in high risk areas are disproportionately affected by disasters compared to their wealthy counterparts; yet, there are few analyses to guide public decisions on pro-poor investments in disaster risk reduction. This paper illustrates an application of benefit-cost analysis (BCA) for assessing investments in structural flood proofing of low-income, high-risk houses. The analysis takes account of climate change, which is increasingly viewed as an important consideration for assessing long-term investments. Specifically, the study focuses on the Rohini river basin of India and evaluates options for constructing non-permanent and permanent residential structures on a raised plinth to protect them against flooding. The estimates show a positive benefit-cost ratio for building new houses on a raised plinth, while the ratio is less than one for demolishing existing houses to rebuild on a raised plinth. Climate change is found to significantly affect the BCA results. From a policy perspective, the analysis demonstrates the potential economic returns of raised plinths for ‘building back better’ after disasters, or as a part of good housing design practice

Biosemiotics, politics and Th.A. Sebeok’s move from linguistics to semiotics

This paper will focus on the political implications for the language sciences of Sebeok’s move from linguistics to a global semiotic perspective, a move that ultimately resulted in biosemiotics. The paper will seek to make more explicit the political bearing of a biosemiotic perspective in the language sciences and the human sciences in general. In particular, it will discuss the definition of language inherent in Sebeok’s project and the fundamental re-drawing of the grounds of linguistic debate heralded by Sebeok’s embrace of the concept of modelling. Thus far, the political co-ordinates of the biosemiotic project have not really been made explicit. This paper will therefore seek to outline 1. how biosemiotics enables us to reconfigure our understanding of the role of language in culture; 2. how exaptation is central to the evolution of language and communication, rather than adaptation; 3. how communication is the key issue in biosphere, rather than language, not just because communication includes language but because the language sciences often refer to language as if it were mere “chatter”, “tropes” and “figures of speech”; 4. how biosemiotics, despite its seeming “neutrality” arising from its transdisciplinarity, is thoroughly political; 5. how the failure to see the implications of the move from linguistics to semiotics arises from the fact that biosemiotics is devoid of old style politics, which is based on representation (devoid of experience) and “construction of [everything] in discourse” (which is grounded in linguistics, not communication study). In contrast to the post-“linguistic turn” idea that the world is “constructed in discourse”, we will argue that biosemiotics entails a reconfiguration of the polis and, in particular, offers the chance to completely reconceptualise ideology

Meta-analysis of mould and dampness exposure on asthma and allergy in eight European birth cohorts: an ENRIECO initiative

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