47 research outputs found
Bounded fitness landscapes and the evolution of the linguistic diversity
A simple spatial computer simulation model was recently introduced to study
the evolution of the linguistic diversity. The model considers processes of
selective geographic colonization, linguistic anomalous diffusion and mutation.
In the approach, we ascribe to each language a fitness function which depends
on the number of people that speak that language. Here we extend the
aforementioned model to examine the role of saturation of the fitness on the
language dynamics. We found that the dependence of the linguistic diversity on
the area after colonization displays a power law regime with a nontrivial
exponent in very good agreement with the measured exponent associated with the
actual distribution of languages on the Earth.Comment: 10 pages, 3 figure
Generalized biomolecular modeling and design with RoseTTAFold All-Atom
Deep learning methods have revolutionized protein structure prediction and design but are currently limited to protein-only systems. We describe RoseTTAFold All-Atom (RFAA) which combines a residue-based representation of amino acids and DNA bases with an atomic representation of all other groups to model assemblies containing proteins, nucleic acids, small molecules, metals, and covalent modifications given their sequences and chemical structures. By fine tuning on denoising tasks we obtain RFdiffusionAA, which builds protein structures around small molecules. Starting from random distributions of amino acid residues surrounding target small molecules, we design and experimentally validate, through crystallography and binding measurements, proteins that bind the cardiac disease therapeutic digoxigenin, the enzymatic cofactor heme, and the light harvesting molecule bilin
A global horizon scan of issues impacting marine and coastal biodiversity conservation
The biodiversity of marine and coastal habitats is experiencing unprecedented change. While there are well-known drivers of these changes, such as overexploitation, climate change and pollution, there are also relatively unknown emerging issues that are poorly understood or recognized that have potentially positive or negative impacts on marine and coastal ecosystems. In this inaugural Marine and Coastal Horizon Scan, we brought together 30 scientists, policymakers and practitioners with transdisciplinary expertise in marine and coastal systems to identify new issues that are likely to have a significant impact on the functioning and conservation of marine and coastal biodiversity over the next 5–10 years. Based on a modified Delphi voting process, the final 15 issues presented were distilled from a list of 75 submitted by participants at the start of the process. These issues are grouped into three categories: ecosystem impacts, for example the impact of wildfires and the effect of poleward migration on equatorial biodiversity; resource exploitation, including an increase in the trade of fish swim bladders and increased exploitation of marine collagens; and new technologies, such as soft robotics and new biodegradable products. Our early identification of these issues and their potential impacts on marine and coastal biodiversity will support scientists, conservationists, resource managers and policymakers to address the challenges facing marine ecosystems
Effect of exposure to sublethal concentrations of sodium cyanide on the carbohydrate metabolism of the Indian Major Carp Labeo rohita (Hamilton, 1822)
Experiments were designed to study in-vivo effects of sodium cyanide on biochemical endpoints in the freshwater fish Labeo rohita. Fish were exposed to two sublethal concentrations (0.106 and 0.064mg/L) for a period of 15 days. Levels of glycogen, pyruvate, lactate and the enzymatic activities of lactate dehydrogenase (LDH), succinate dehydrogenase (SDH), glucose-6-phosphate dehydrogenase (G6PDH), phosphorylase, alkaline phosphatase (ALP), acid phosphatase (AcP) were assessed in different tissues (liver, muscle and gills). Result indicated a steady decrease in glycogen, pyruvate, SDH, ALP and AcP activity with a concomitant increase in the lactate, phosphorylase, LDH and G6PD activity in all selected tissues. The alterations in all the above biochemical parameters were significantly (p<0.05) time and dose dependent. In all the above parameters, liver pointing out the intensity of cyanide intoxication compare to muscle and gills. Study revealed change in the metabolic energy by means of altered metabolic profile of the fish. Further, these observations indicated that even sublethal concentrations of sodium cyanide might not be fully devoid of deleterious influence on metabolism in L. rohita
A roadmap for Antarctic and Southern Ocean science for the next two decades and beyond
Antarctic and Southern Ocean science is vital to understanding natural variability, the processes
that govern global change and the role of humans in the Earth and climate system. The potential for new
knowledge to be gained from future Antarctic science is substantial. Therefore, the international Antarctic
community came together to ‘scan the horizon’ to identify the highest priority scientific questions that
researchers should aspire to answer in the next two decades and beyond. Wide consultation was a
fundamental principle for the development of a collective, international view of the most important future
directions in Antarctic science. From the many possibilities, the horizon scan identified 80 key scientific
questions through structured debate, discussion, revision and voting. Questions were clustered into seven
topics: i)Antarctic atmosphere and global connections, ii) Southern Ocean and sea ice in a warming world,
iii) ice sheet and sea level, iv) the dynamic Earth, v) life on the precipice, vi) near-Earth space and beyond,
and vii) human presence in Antarctica. Answering the questions identified by the horizon scan will require
innovative experimental designs, novel applications of technology, invention of next-generation field and
laboratory approaches, and expanded observing systems and networks. Unbiased, non-contaminating
procedures will be required to retrieve the requisite air, biota, sediment, rock, ice and water samples.
Sustained year-round access toAntarctica and the Southern Ocean will be essential to increase winter-time
measurements. Improved models are needed that represent Antarctica and the Southern Ocean in the
Earth System, and provide predictions at spatial and temporal resolutions useful for decision making.
A co-ordinated portfolio of cross-disciplinary science, based on new models of international collaboration,
will be essential as no scientist, programme or nation can realize these aspirations alone.Tinker Foundation, Antarctica New Zealand, The New Zealand
Antarctic Research Institute, the Scientific Committee on
Antarctic Research (SCAR), the Council of Managers of
National Antarctic Programs (COMNAP), the Alfred
Wegner Institut, Helmholtz Zentrum für Polar und
Meeresforschung (Germany), and the British Antarctic
Survey (UK).http://journals.cambridge.org/action/displayJournal?jid=ANShb201
Search for patterns by combining cosmic-ray energy and arrival directions at the Pierre Auger Observatory
Energy-dependent patterns in the arrival directions of cosmic rays are searched for using data of the Pierre Auger Observatory. We investigate local regions around the highest-energy cosmic rays with E > = 6×1019 eV by analyzing cosmic rays with energies above E > = 5×1018 eV arriving within an angular separation of approximately 15°. We characterize the energy distributions inside these regions by two independent methods, one searching for angular dependence of energy-energy correlations and one searching for collimation of energy along the local system of principal axes of the energy distribution. No significant patterns are found with this analysis. The comparison of these measurements with astrophysical scenarios can therefore be used to obtain constraints on related model parameters such as strength of cosmic-ray deflection and density of point sources
Pigments of marine animals:XI. Angular naphthopyrones from the crinoid comanthus parvicirrus timorensis
Green specimens of the comatulid crinoid, Comanthus parvicirrus timorensis J. Muller, yield to acetone three yellow water-soluble colouring matters, comaparvin sulphate, 6-methoxycomaparvin sulphate, and 6-methoxycomaparvin 5-methyl ether sulphate in approximately 0.1 %, 0.7 %, and 0.7 % yield respectively of the dry weight of the animal, Mild acid hydrolysis yields the corresponding phenols, the structures of which have been deduced largely by spectral studies as very probably 5, 8-dihydroxy-10-methoxy-2-n-propyl-4H-naphtho[1, 2-b]pyran-4-one (1), the 6-methoxy derivative of (1), and the 6-methoxy methyl ether of (1) respectively. A yellow colour variant of the same species yielded the same colouring matters in slightly different proportions. The calcareous skeleton contains what are probably polyhydroxynaphthoquinones in combined form
Sources and geographic heterogeneity of trace metals in the sediments of Prydz Bay, East Antarctica
In this study, we have determined the contents and distribution of zinc and cadmium in the surface sediments from Prydz Bay, East Antarctica. The main sources of the trace elements and their geographic heterogeneity, and the relation between Zn and Cd, are discussed based on the cluster analysis, principle component analysis and considerations of biogenic and lithogenic inputs. The results show that the contents of trace metals range from 34.6 to 96.6 mg kg−1 for Zn, and from 0.254 to 0.441 mg kg−1 for Cd. Calculations of the enrichment factor indicated no significant anthropogenic impact. Biogenic and lithogenic inputs are the main sources of trace metals. They are almost equal for Zn and Cd at the Amery Ice Shelf edge, while the continental shelf and deep ocean are dominated by biogenic inputs. The contribution of biogenic inputs is much higher for Zn than for Cd at the deep ocean. Calculations of biogenic trace metals revealed different relationships between biogenic Zn and biogenic Cd, which reflect the biological uptake by phytoplankton in the water column