The spatial and temporal dynamics of diversification in Tylecodon, Cotyledon and Adromischus (Crassulaceae) in southern Africa

Includes abstract.Includes bibliographical references (leaves 105-119).A molecular phylogenetic hypothesis was generated for Tylecodon, Cotyledon and Adromischus in order to estimate the timing and spatial dynamics of diversification across these three southern African genera. These data were used to investigate the correlates and consequences of adaptations to extreme aridity and summer drought in members of the group

The Threats of Sea Level Rise: An Eco-Geopolitical Visual Analysis

This eco-geopolitical research produces information about the sea level rising, and the analyst explains and projects global effects, and further problems and consequences of the phenomena in a five-minute-long video clip. The focus is coastlines floods as a consequence of the sea level rising produced by glaciers melting. The floods will affect regions where over a billion persons are living, mainly coastal cities. Therefore, the sea level rising will produce or ease gradual destruction and sudden catastrophes. Moreover, these catastrophes will spur mass migration that might change the lives of a billion persons by 2045

cyTRON and cyTRON/JS: two Cytoscape-based applications for the inference of cancer evolution models

The increasing availability of sequencing data of cancer samples is fueling the development of algorithmic strategies to investigate tumor heterogeneity and infer reliable models of cancer evolution. We here build up on previous works on cancer progression inference from genomic alteration data, to deliver two distinct Cytoscape-based applications, which allow to produce, visualize and manipulate cancer evolution models, also by interacting with public genomic and proteomics databases. In particular, we here introduce cyTRON, a stand-alone Cytoscape app, and cyTRON/JS, a web application which employs the functionalities of Cytoscape/JS. cyTRON was developed in Java; the code is available at https://github.com/BIMIB-DISCo/cyTRON and on the Cytoscape App Store http://apps.cytoscape.org/apps/cytron. cyTRON/JS was developed in JavaScript and R; the source code of the tool is available at https://github.com/BIMIB-DISCo/cyTRON-js and the tool is accessible from https://bimib.disco.unimib.it/cytronjs/welcome

Enhanced deposition to pits: A local food source for benthos

Particle deposition experiments using mimics of biogenous negative relief (“pits”) and low-excess-density particles in a small annular flume indicate a significantly enhanced deposition rate (number of particles per time) compared to smooth, flat patches of the same diameter. This study included flow visualizations as well as observations of particle residence times, particle concentrations in the pits, and particle fluxes to the pits from the main flow. Experimental conditions of particle concentration, shear velocity, and particle settling velocity mimicked the dynamic characteristics (low excess density and large size) of organic-rich flocs and flow conditions in the subtidal and deep sea where biogenous pits are common features. Results suggest that pits provide benthic organisms an important capture mechanism for such flocs. Flow visualizations concur qualitatively with previously reported results for two-dimensional cavity flow, with unique features due to the conical shape of the pits. When the Rouse number (settling velocity/shear velocity) was much less than 1, pit deposition rate increased with increasing pit aspect ratio (AR = depth/diameter; ranging from 0.25 to 2) and always exceeded deposition to a flat patch of comparable diameter. For the single aspect ratio tested (AR = 0.5) under conditions of increasing turbulence, deposition to the pit increased under transitional flow, but then decreased to near zero when conditions reached fully rough flow. Relative enhancement of deposition to this pit decreased with increased ambient bed roughness since gravel beds also effectively collect particles. Particle concentration inside pits decreased weakly with pit aspect ratio but greatly increased with increasing roughness Reynolds number. Particle residence time increased somewhat with pit aspect ratio but decreased significantly with increasing roughness Reynolds number. Particle flux into pits from the main flow increased with both increasing aspect ratio and increasing roughness Reynolds number. Enhancement of food supply to pit inhabitants thus depends on the flow regime

A Doppler-Cancellation Technique for Determining the Altitude Dependence of Gravitational Red Shift in an Earth Satellite

A cancellation technique permits measurement of the frequency of a source moving relative to an observer without the obscuring effect of first-order Doppler shifts. The application of this method to a gravitational red shift experiment involving the use of an earth satellite containing a highly stable oscillator is described. The rapidity with which a measurement can be made permits the taking of data at various altitudes in a given elliptical orbit. Tropospheric and ionospheric effects upon the accuracy of results are estimated

Ultrasonic monitoring of friction contacts during shear vibration cycles

Complex high-value jointed structures such as aero-engines are carefully designed and optimized to prevent failure and maximise their life. In the design process, physically-based numerical models are employed to predict the nonlinear dynamic response of the structure. However, the reliability of these models is limited due to the lack of accurate validation data from metallic contact interfaces subjected to high-frequency vibration cycles. In this study, ultrasonic shear waves are used to characterise metallic contact interfaces during vibration cycles, hence providing new validation data for an understanding of the state of the friction contact. Supported by numerical simulations of wave propagation within the material, a novel experimental method is developed to simultaneously acquire ultrasonic measurements and friction hysteresis loops within the same test on a high-frequency friction rig. Large variability in the ultrasound reflection/transmission is observed within each hysteresis loop and is associated with stick/slip transitions. The measurement results reveal that the ultrasound technique can be used to detect stick and slip states in contact interfaces subjected to high-frequency shear vibration. This is the first observation of this type and paves the way towards real-time monitoring of vibrating contact interfaces in jointed structures, leading to a new physical understanding of the contact states and new validation data needed for improved nonlinear dynamic analyses

Phylogenetic relationships of haplolepideous mosses (Dicranidae) inferred from rps4 gene sequences

The haplolepideous mosses (Dicranidae) constitute a large group of ecologically and morphologically diverse species recognised primarily by having peristome teeth with a single row of cells on the dorsal surface

Commensurate lattice distortion in the layered titanium oxypnictides Na2_{2}Ti2Pn2_{2}Pn_{2}O (Pn=Pn = As, Sb) determined by X-ray diffraction

We report single crystal X-ray diffraction measurements on Na$_2$Ti$_{2}Pn_{2}$O ($Pn$ = As, Sb) which reveal a charge superstructure that appears below the density wave transitions previously observed in bulk data. From symmetry-constrained structure refinements we establish that the associated distortion mode can be described by two propagation vectors, ${\bf q}_{1} = (1/2, 0, l)$ and ${\bf q}_{2} = (0, 1/2, l)$, with $l=0$ (Sb) or $l = 1/2$ (As), and primarily involves in-plane displacements of the Ti atoms perpendicular to the Ti--O bonds. The results provide direct evidence for phonon-assisted charge density wave order in Na$_2$Ti$_{2}Pn_{2}$O and identify a proximate ordered phase that could compete with superconductivity in doped BaTi$_{2}$Sb$_{2}$O

European wildcat populations are subdivided into five main biogeographic groups: consequences of Pleistocene climate changes or recent anthropogenic fragmentation?

Extant populations of the European wildcat are fragmented across the continent, the likely consequence of recent extirpations due to habitat loss and over-hunting. However, their underlying phylogeographic history has never been reconstructed. For testing the hypothesis that the European wildcat survived the Ice Age fragmented in Mediterranean refuges, we assayed the genetic variation at 31 microsatellites in 668 presumptive European wildcats sampled in 15 European countries. Moreover, to evaluate the extent of subspecies/population divergence and identify eventual wild × domestic cat hybrids, we genotyped 26 African wildcats from Sardinia and North Africa and 294 random-bred domestic cats. Results of multivariate analyses and Bayesian clustering confirmed that the European wild and the domestic cats (plus the African wildcats) belong to two well-differentiated clusters (average Ф ST = 0.159, r st = 0.392, P > 0.001; Analysis of molecular variance [AMOVA]). We identified from c. 5% to 10% cryptic hybrids in southern and central European populations. In contrast, wild-living cats in Hungary and Scotland showed deep signatures of genetic admixture and introgression with domestic cats. The European wildcats are subdivided into five main genetic clusters (average Ф ST = 0.103, r st = 0.143, P > 0.001; AMOVA) corresponding to five biogeographic groups, respectively, distributed in the Iberian Peninsula, central Europe, central Germany, Italian Peninsula and the island of Sicily, and in north-eastern Italy and northern Balkan regions (Dinaric Alps). Approximate Bayesian Computation simulations supported late Pleistocene-early Holocene population splittings (from c. 60 k to 10 k years ago), contemporary to the last Ice Age climatic changes. These results provide evidences for wildcat Mediterranean refuges in southwestern Europe, but the evolution history of eastern wildcat populations remains to be clarified. Historical genetic subdivisions suggest conservation strategies aimed at enhancing gene flow through the restoration of ecological corridors within each biogeographic units. Concomitantly, the risk of hybridization with free-ranging domestic cats along corridor edges should be carefully monitored