Transport of Po Valley aerosol pollution to the northwestern Alps – Part 1: Phenomenology

Mountainous regions are often considered pristine environments; however they can be affected by pollutants emitted in more populated and industrialised areas, transported by regional winds. Based on experimental evidence, further supported by modelling tools, here we demonstrate and quantify the impact of air masses transported from the Po Valley, a European atmospheric pollution hotspot, to the northwestern Alps. This is achieved through a detailed investigation of the phenomenology of near-range (a few hundred kilometres), trans-regional transport, exploiting synergies of multi-sensor observations mainly focussed on particulate matter. The explored dataset includes vertically resolved data from atmospheric profiling techniques (automated lidar ceilometers, ALCs), vertically integrated aerosol properties from ground (sun photometer) and space, and in situ measurements (PM10 and PM2.5, relevant chemical analyses, and aerosol size distribution). During the frequent advection episodes from the Po basin, all the physical quantities observed by the instrumental setup are found to significantly increase: the scattering ratio from ALC reaches values &gt;30, aerosol optical depth (AOD) triples, surface PM10 reaches concentrations &gt;100&thinsp;µg m−3 even in rural areas, and contributions to PM10 by secondary inorganic compounds such as nitrate, ammonium, and sulfate increase up to 28&thinsp;%, 8&thinsp;%, and 17&thinsp;%, respectively. Results also indicate that the aerosol advected from the Po Valley is hygroscopic, smaller in size, and less light-absorbing compared to the aerosol type locally emitted in the northwestern Italian Alps. In this work, the phenomenon is exemplified through detailed analysis and discussion of three case studies, selected for their clarity and relevance within the wider dataset, the latter being fully exploited in a companion paper quantifying the impact of this phenomenology over the long-term (Diémoz et al., 2019). For the three case studies investigated, a high-resolution numerical weather prediction model (COSMO) and a Lagrangian tool (LAGRANTO) are employed to understand the meteorological mechanisms favouring transport and to demonstrate the Po Valley origin of the air masses. In addition, a chemical transport model (FARM) is used to further support the observations and to partition the contributions of local and non-local sources. Results show that the simulations are important to the understanding of the phenomenon under investigation. However, in quantitative terms, modelled PM10 concentrations are 4–5 times lower than the ones retrieved from the ALC and maxima are anticipated in time by 6–7&thinsp;h. Underestimated concentrations are likely mainly due to deficiencies in the emission inventory and to water uptake of the advected particles not fully reproduced by FARM, while timing mismatches are likely an effect of suboptimal simulation of up-valley and down-valley winds by COSMO. The advected aerosol is shown to remarkably degrade the air quality of the Alpine region, with potential negative effects on human health, climate, and ecosystems, as well as on the touristic development of the investigated area. The findings of the present study could also help design mitigation strategies at the trans-regional scale in the Po basin and suggest an observation-based approach to evaluate the outcome of their implementation.</p

Length Sensing and Control in the Virgo Gravitational Wave Interferometer

The gravitational wave detector Virgo is presently being commissioned. A significant part of last year was spent in setting up the cavity length control system. This work was carried out with steps of increasing complexity: locking a simple Fabry-Perot cavity, then a Michelson interferometer with Fabry-Perot cavities in both arms, and finally recycling the light beam into the interferometer. The applied strategy and the main results obtained are describe

The Virgo interferometric gravitational antenna

Submitted to: Class. Quantum Grav.The interferometric gravitational wave detectors represent the ultimate evolution of the classical Michelson interferometer. In order to measure the signal produced by the passage of a gravitational wave, they aim to reach unprecedent sensitivities in measuring the relative displacements of the mirrors. One of them , the 3-km-long Virgo gravitational wave antenna, which will be particularly sensitive in the low frequency range (10-100 Hz), is presently in its commissioning phase. In this paper the various techniques developed in order to reach its target extreme performance are outlined

Micropropagação de violeta-africana (Saintpaulia ionantha Wendl.): efeito da Benzilaminopurina na multiplicação Micropropagation of African-Violet (Saintpaulia ionantha Wendl.): effect of Benzylaminopurine on multiplication

A violeta-africana (Saintpaulia ionantha Wendl.) é uma espécie cultivada como ornamental pela beleza de suas flores e folhagem. A Benzilaminopurina (BAP) pode ser utilizada na multiplicação in vitro dessa espécie, no entanto, inexistem informações mais detalhadas sobre as respostas obtidas sobre a multiplicação, em uma faixa ampla de concentrações. Objetivou-se com este trabalho determinar o efeito do BAP na multiplicação in vitro de violeta-africana. Foram utilizados, como explantes, tufos de brotações das cultivares Optimara Miki, Optimara Maki e Optimara Akemi, com tamanhos entre 0,8 e 2,0 cm. Empregou-se o meio MS, com concentrações de nutrientes minerais e vitaminas reduzidas à metade, suplementado com mio-inositol (100mg L-1), sacarose (30 g L-1) e ágar (7 g L-1). Os tratamentos utilizados foram: 0,0; 0,44; 1,78; 3,08 e 4,44 mM de BAP. O pH do meio foi ajustado para 5,8 antes da esterilização. O material vegetal permaneceu em temperatura de 24 ± 2 ºC, fotoperíodo de 14 horas e densidade de fluxo luminoso de 40 mmol c4m-2 s-1. As avaliações do número total de brotações e do número e altura de brotações maiores que 3 mm foram realizadas aos 46 dias. A adição de BAP ao meio de cultura foi essencial para a multiplicação das culturas. As respostas aos tratamentos variaram entre os genótipos utilizados. Maiores resultados de número total de brotações e número de brotações superiores que três milímetros foram observados em concentrações de BAP situadas entre 1,78 e 4,44 mM. A altura das brotações decresceu com a utilização de BAP.<br>African-Violet (Saintpaulia ionantha Wendl.) is an ornamental plant widely cultivated, because of its beautiful foliage and flowers. Benzylaminopurine (BAP) can be used to violet multiplication, but there weren't information about results with several concentrations. The aim of this work was to determine the effect of different concentrations of BAP on the multiplication of violet cultures. One utilized, as explants, shoot clusters of cultivars Optimara Miki, Optimara Maki e Optimara Akemfrom, with height from 0,8 to 2,0 cm. One utilized MS medium, with half concentration of mineral nutrients and vitamins, suplementated with myo-inositol (100 mg L-1), sucrose (30 g L-1) and agar (7 g L-1). The treatments applied were: 0.0, 0.44, 1.78, 3,08 e 4,44 mM of BAP. The pH of the medium was adjusted to 5,8 before sterilization. Cultures remained at 24 ± 2 ºC, photoperiod of 14 hours and 40 mmol cm-2 s-1 of light density flux. Total shoot number and number and height of shoots with more than three millimeters were evaluated at 46 days. Addition of BAP to the culture medium was essential to multiplication of cultures. Responses of treatments varied between cultivars. Best results of total shoot number and number shoots with more than three millimeters were found with concentrations between 1.78 e 4.44 mM. The height of shoots decreased with the addition of BAP

From laboratory experiments to LISA Pathfinder: achieving LISA geodesic motion

This paper presents a quantitative assessment of the performance of the upcoming LISA Pathfinder geodesic explorer mission. The findings are based on the results of extensive ground testing and simulation campaigns using flight hardware, flight control and operations algorithms. The results show that, for the central experiment of measuring the stray differential acceleration between the LISA test masses, LISA Pathfinder will be able to verify the overall acceleration noise to within a factor 2 of the LISA requirement at 1 mHz and within a factor 6 at 0.1 mHz. We also discuss the key elements of the physical model of disturbances, coming from LISA Pathfinder and ground measurement that will guarantee the LISA performance

Reversible Gelation of Rod-Like Viruses Grafted with Thermoresponsive Polymers

The synthesis and selected macroscopic properties of a new model system consisting of poly(N-isopropylacrylamide) (PNIPAM)-coated rod-like fd virus particles are presented. The sticky rod-like colloids can be used to study effect of particle shape on gelation transition, the structure and viscoelasticity of isotropic and nematic gels, and to make both open isotropic as well as ordered nematic particle networks. This model system of rod-like colloids, for which the strength of attraction between the particles is tunable, is obtained by chemically grafting highly monodisperse rod-like fd virus particles with thermoresponsive polymers, e.g. PNIPAM. At room temperature, suspensions of the resulting hybrid PNIPAM-fd are fluid sols which are in isotropic or liquid crystalline phases, depending on the particle concentration and ionic strength. During heating/cooling, the suspensions change reversibly between sol and gel state near a critical temperature of ∼32 °C, close to the lower critical solution temperature of free PNIPAM. The so-called nematic gel, which exhibits a cholesteric feature, can therefore be easily obtained. The gelation behavior of PNIPAM-fd system and the structure of the nematic gel have been characterized by rheology, optical microscopy and small-angle X-ray scattering