The VOL-CALPUFF model for atmospheric ash dispersal: 1. Approach and physical formulation

We present a new modeling tool, named VOL-CALPUFF, that is able to simulate the transient and three-dimensional transport and deposition of volcanic ash under the action of realistic meteorological and volcanological conditions throughout eruption duration. The new model derives from the CALPUFF System, a software program widely used in environmental applications of pollutant dispersion, that describes the dispersal process in both the proximal and distal regions and also in the presence of complex orography. The main novel feature of the model is its capability of coupling a Eulerian description of plume rise with a Lagrangian representation of ash dispersal described as a series of diffusing packets of particles or puffs. The model is also able to describe the multiparticle nature of the mixture as well as the tilting effects of the plume due to wind action. The dispersal dynamics and ash deposition are described by using refined orography-corrected meteorological data with a spatial resolution up to 1 km or less and a temporal step of 1 h. The modeling approach also keeps the execution time to a few minutes on common PCs, thus making VOL-CALPUFF a possible tool for the production of ash dispersal forecasts for hazard assessment. Besides the model formulation, this paper presents the type of outcomes produced by VOL-CALPUFF, shows the effect of main model parameters on results, and also anticipates the fundamental control of atmospheric conditions on the ash dispersal processes. In the companion paper, Barsotti and Neri present a first thorough application of VOL-CALPUFF to the simulation of a weak plume at Mount Etna (Italy) with the specific aim of comparing model predictions with independent observations

The VOL-CALPUFF model for atmospheric ash dispersal. I. Approach and physical formulation

We present a new modeling tool, named VOL-CALPUFF able to simulate the transient and three-dimensional transport and deposition of volcanic ash under the action of realistic meteorological and volcanological conditions throughout eruption duration. The new model derives from the CALPUFF System, a software program widely-used in environmental applications of pollutant dispersion, that describes the dispersal process both in the proximal and distal regions and also in presence of complex orography. The main novel feature of the model is its capability of coupling a Eulerian description of plume rise with a Lagrangian representation of ash dispersal described as a series of diffusing packets of particles or puffs. The model is also able to describe the multiparticle nature of the mixture as well as the tilting effects of the plume due to wind action. The dispersal dynamics and ash deposition are described by using refined orography-corrected meteorological data with a spatial resolution up to 1 km or less and a temporal step of 1 hour. The modeling approach also keeps the execution time to a few minutes on common PCs, thus making VOL-CALPUFF a possible tool for the production of ash dispersal forecasts for hazard assessment. Besides the model formulation, the paper presents the type of outcomes produced by VOL-CALPUFF, shows the effect of main model parameters on results, and also anticipates the fundamental control of atmospheric conditions on the ash dispersal processes. In the companion paper (\cite{barsotti}, this issue) a first thorough application of VOL-CALPUFF to the simulation of a weak plume at Mount Etna (Italy) is presented with the specific aim of comparing model predictions with independent observations

Topological insight into the non-Arrhenius mode hopping of semiconductor ring lasers

We investigate both theoretically and experimentally the stochastic switching between two counter-propagating lasing modes of a semiconductor ring laser. Experimentally, the residence time distribution cannot be described by a simple one parameter Arrhenius exponential law and reveals the presence of two different mode-hop scenarios with distinct time scales. In order to elucidate the origin of these two time scales, we propose a topological approach based on a two-dimensional dynamical system.Comment: 4 pages, 3 figure

Adiponectin levels are reduced in children born small for gestational age and are inversely related to postnatal catch-up growth

Adiponectin is an adipocytokine with insulin-sensitizing and antiatherogenic properties. Reduced concentrations of adiponectin precede the onset of type 2 diabetes and the development of atherosclerosis. Our aim was to quantify adiponectin concentrations in small for gestational age (SGA) children. Fifty-one SGA children, 24 obese, and 17 short-normal children with birth weight appropriate for gestational age (short-AGA) were studied. The statures of the SGA children were corrected for their midparental height and subdivided into two groups according to their corrected height: catch-up growth group, children with corrected height of 0 z-score or greater (n = 17); and noncatch-up growth group, subjects with corrected height less than 0 z-score (n = 34). SGA children showed adiponectin levels significantly lower than short-normal children (35.2 +/- 3.5 vs. 80.4 +/- 26.6 mug/ml; P < 0.0001) and obese children (77.5 +/- 39.4 μg/ml; P < 0.0001). Catch-up growth children showed adiponectin levels significantly lower than noncatch-up growth subjects (29.4 +/- 10.3 vs. 38.1 +/- 11.5 mug/ml; P = 0.01). Adiponectin concentrations were inversely related to height z-score, corrected stature, weight, and body mass index and were positively related to birth weight. Our results suggest that adiponectin levels are reduced in SGA children and are even lower in those with postnatal catch-up growth. Whether this finding implies a higher risk of developing type 2 diabetes and atherosclerosis remains to be established

Thermal stability and aggregation of sulfolobus solfataricus b-glycosidase are dependent upon the N-e-methylation of specific lysyl residues: critical role of in vivo post-translational modifications.

Methylation in vivo is a post-translational modification observed in several organisms belonging to eucarya, bacteria, and archaea. Although important implications of this modification have been demonstrated in several eucaryotes, its biological role in hyperthermophilic archaea is far from being understood. The aim of this work is to clarify some effects of methylation on the properties of β-glycosidase from Sulfolobus solfataricus, by a structural comparison between the native, methylated protein and its unmethylated counterpart, recombinantly expressed in Escherichia coli. Analysis by Fourier transform infrared spectroscopy indicated similar secondary structure contents for the two forms of the protein. However, the study of temperature perturbation by Fourier transform infrared spectroscopy and turbidimetry evidenced denaturation and aggregation events more pronounced in recombinant than in native β-glycosidase. Red Nile fluorescence analysis revealed significant differences of surface hydrophobicity between the two forms of the protein. Unlike the native enzyme, which dissociated into SDS-resistant dimers upon exposure to the detergent, the recombinant enzyme partially dissociated into monomers. By electrospray mapping, the methylation sites of the native protein were identified. A computational analysis of β-glycosidase three-dimensional structure and comparisons with other proteins from S. solfataricus revealed analogies in the localization of methylation sites in terms of secondary structural elements and overall topology. These observations suggest a role for the methylation of lysyl residues, located in selected domains, in the thermal stabilization of β-glycosidase from S. solfataricu

Spitzer Warm Mission Transition and Operations

Following the successful dynamic planning and implementation of IRAC Warm Instrument Characterization activities, transition to Spitzer Warm Mission operations has gone smoothly. Operation teams procedures and processes required minimal adaptation and the overall composition of the Mission Operation System retained the same functionality it had during the Cryogenic Mission. While the warm mission scheduling has been simplified because all observations are now being made with a single instrument, several other differences have increased the complexity. The bulk of the observations executed to date have been from ten large Exploration Science programs that, combined, have more complex constraints, more observing requests, and more exo-planet observations with durations of up to 145 hours. Communication with the observatory is also becoming more challenging as the Spitzer DSN antenna allocations have been reduced from two tracking passes per day to a single pass impacting both uplink and downlink activities. While IRAC is now operating with only two channels, the data collection rate is roughly 60% of the four-channel rate leaving a somewhat higher average volume collected between the less frequent passes. Also, the maximum downlink data rate is decreasing as the distance to Spitzer increases requiring longer passes. Nevertheless, with well over 90% of the time spent on science observations, efficiency has equaled or exceeded that achieved during the cryogenic mission

Selective aqueous oxidation of aromatic alcohols under solar light in the presence of TiO2 modified with different metal species

A set of metals modified TiO2 photocatalysts were prepared starting from titanium tetraisopropoxyde and different metal precursors to study the influence of the addition of the various foreign agents on the physico-chemical and photocatalytic properties of the catalysts. The powders were characterized by X-ray diffraction, Raman spectroscopy, specific surface area measurements, scanning electron microscopy, energy dispersive X-ray spectroscopy, UV–Vis diffuse reflectance spectroscopy, photoluminescence, temperature programmed desorption after CO2 adsorption. The photocatalytic activity was evaluated using as probe reactions the partial oxidation of three aromatic alcohols: benzyl alcohol (BA), 4-methoxy benzyl alcohol (4-MBA), and 4-hydroxy benzyl alcohol (4-HBA) under simulated solar light irradiation. Different oxidation and selectivity values were obtained for the three substrates depending not only on the type of metals but also on the nature and position of the substituent in the phenyl ring of benzyl alcohol. As a general behaviour, the doped samples allowed the achievement of a greater selectivity especially for 4-MBA even if sometimes with minor conversions. The presence of W or Nb was beneficial for both conversion and selectivity for all the substrates with respect to bare TiO2. Graphical abstract: [Figure not available: see fulltext.

Exploring the photothermo-catalytic performance of brookite tio2-ceo2 composites

The thermocatalytic, photocatalytic and photothermo-catalytic oxidation of some volatile organic compounds (VOCs), 2-propanol, ethanol and toluene, was investigated over brookite TiO2-CeO2 composites. The multi-catalytic approach based on the synergistic effect between solar photocatalysis and thermocatalysis led to the considerable decrease in the conversion temperatures of the organic compounds. In particular, in the photothermo-catalytic runs, for the most active samples (TiO2-3 wt% CeO2 and TiO2-5 wt% CeO2). the temperature at which 90% of VOC conversion occurred was about 60◦ C, 40◦ C and 20◦ C lower than in the thermocatalytic tests for 2-propanol, ethanol and toluene, respectively. Furthermore. the addition of cerium oxide to brookite TiO2 favored the total oxidation to CO2 already in the photocatalytic tests at room temperature. The presence of small amounts of cerium oxide allowed to obtain efficient brookite-based composites facilitating the space charge separation and increasing the lifetime of the photogenerated holes and electrons as confirmed by the characterization measurements. The possibility to concurrently utilize the photocatalytic properties of brookite and the redox properties of CeO2, both activated in the photothermal tests, is an attractive approach easily applicable to purify air from VOCs

A solar photothermocatalytic approach for the CO2 conversion: Investigation of different synergisms on CoO-CuO/brookite TiO2-CeO2 catalysts

The photoactive features of the least common polymorph of TiO2, i.e. brookite, were combined with the thermocatalytic redox ones of cerium oxide, focusing on the effects of the addition of small amounts of Co-Cu oxides for the solar CO2 conversion. By considering the characterization data, a surface segregation of the hosted metal oxides on the TiO2-CeO2 composite was evidenced, and their presence increased the amount of oxygen vacancies and improved the charge carriers separation. The bimetallic oxides-based sample was the most performing one in the photocatalytic carbon dioxide reduction at room temperature. The formation of carbon monoxide and methane was 5 and 0.5 μmol g−1h−1, respectively, i.e. about 10 times higher than that found with bare brookite. A further enhancement was obtained with the same CoO-CuO/TiO2-CeO2 catalyst applying the photothermal approach. The CO2-TPD and the FTIR measurements highlighted the high interaction between CO2 and the surface sites

Estimation and worldwide monitoring of the effective reproductive number of SARS-CoV-2

The effective reproductive number; R; e; is a key indicator of the growth of an epidemic. Since the start of the SARS-CoV-2 pandemic, many methods and online dashboards have sprung up to monitor this number through time. However, these methods are not always thoroughly tested, correctly placed in time, or are overly confident during high incidence periods. Here, we present a method for timely estimation of; R; e; , applied to COVID-19 epidemic data from 170 countries. We thoroughly evaluate the method on simulated data, and present an intuitive web interface for interactive data exploration. We show that, in early 2020, in the majority of countries the estimated; R; e; dropped below 1 only after the introduction of major non-pharmaceutical interventions. For Europe the implementation of non-pharmaceutical interventions was broadly associated with reductions in the estimated; R; e; . Globally though, relaxing non-pharmaceutical interventions had more varied effects on subsequent; R; e; estimates. Our framework is useful to inform governments and the general public on the status of epidemics in their country, and is used as the official source of; R; e; estimates for SARS-CoV-2 in Switzerland. It further allows detailed comparison between countries and in relation to covariates such as implemented public health policies, mobility, behaviour, or weather data