196,576 research outputs found
Summertime Primary and Secondary Contributions to Southern Ocean Cloud Condensation Nuclei
No full textAtmospheric aerosols in clean remote oceanic regions contribute significantly to the global albedo through the formation of haze and cloud layers; however, the relative importance of ‘primary’ wind-produced sea-spray over secondary (gas-to-particle conversion) sulphate in forming marine clouds remains unclear. Here we report on marine aerosols (PM1) over the Southern Ocean around Antarctica, in terms of their physical, chemical, and cloud droplet activation properties. Two predominant pristine air masses and aerosol populations were encountered: modified continental Antarctic (cAA) comprising predominantly sulphate with minimal sea-salt contribution and maritime Polar (mP) comprising sulphate plus sea-salt. We estimate that in cAA air, 75% of the CCN are activated into cloud droplets while in mP air, 37% are activated into droplets, for corresponding peak supersaturation ranges of 0.37–0.45% and 0.19–0.31%, respectively. When realistic marine boundary layer cloud supersaturations are considered (e.g. ~0.2–0.3%), sea-salt CCN contributed 2–13% of the activated nuclei in the cAA air and 8–51% for the marine air for surface-level wind speed < 16 m s−1. At higher wind speeds, primary marine aerosol can even contribute up to 100% of the activated CCN, for corresponding peak supersaturations as high as 0.32%. © 2018, The Author(s)
Hydatothrips gliricidiae Mound & Marullo
No full textHydatothrips gliricidiae Mound & Marullo (Figs 6, 12) Hydatothrips gliricidiae Mound & Marullo, 1996: 161. Female macroptera. Colour: body mainly yellow, head, anterior two thirds of metanotum and tergites II–III and VII brown, tergites I and IV–V pale; antennal segments I–II pale, III yellow with apical third shaded brown, IV brown with apex and base yellow, V yellow basally and increasingly darker to brown apex, VI–VIII brown; legs yellow with shaded brown areas medially; fore wings with three pale and three brown bands, apex pale. Structure: Occipital apodeme confluent with posterior margin of eyes, ocellar area transversely striate without internal markings; pronotum with anterior area transversely striate forming a few transverse reticles without markings between the major lines, blotch distinct (Fig. 6); mesonotum transversely striate with several minute microtrichia-like lines, metanotum with transverse striae on anterior half, longitudinal striae on posterior half with internal lines (Fig. 12); fore wing second vein with two setae; posteromarginal comb on tergites II–VI incomplete medially, VII–VIII complete; tergite IX with with 4 pairs of mid-dorsal setae; sternites III–V and VII without microtrichia medially, VI with a few rows of microtrichia medially. Male macroptera. Similar to female, but smaller and with darker abdominal tergites VII–VIII. Sternite VII with a small circular pore plate. Larva II. Yellow without markings; antennae 7-segmented; thorax without brown sclerotized areas; body with setae short, with broadly expanded apices (Mound & Marullo 1996). Material studied. Holotype female and two paratype males, COSTA RICA, Braulio Carrillo NP, Volcan Barba Station (2500 m), on Malaise trap, vi.1990 (BMNH). Comments. Associated with Gliricidia leaves in Central America, this species is unique amongst Neotropical Hydatothrips in having the fore wing with three pale and brown bands. It is also the only species in this genus that has several microtrichia-like structures both on the mesonotum and metanotum. In the Holarctic area, Sericothrips species bear microtrichia on the metanotum, but differently from H. gliricidiae, and have the entire surface of the abdominal tergites covered with microtrichia and a more transverse metasternal plate.Published as part of Lima, Élison Fabrício B. & Mound, Laurence A., 2016, Species-richness in Neotropical Sericothripinae (Thysanoptera: Thripidae), pp. 1-45 in Zootaxa 4162 (1) on pages 6-7, DOI: 10.11646/zootaxa.4162.1.1, http://zenodo.org/record/26386
Ionic liquid gel materials: Applications in green and sustainable chemistry
No full textGels are a class of materials with a wide range of applications, for their convenient properties. In the last decade, gels in non-conventional solvents like ionic liquids, known as Ionic Liquid Gels, have gained a surge in interest, due to the possibility of conjugating the properties of gels with the ones of ionic liquids. In particular, this chapter will cover literature from 2012, dealing with applications of ionic liquids gels in green and sustainable chemistry, laying focus on catalysis, sensing, CO2 capture, environmental remediation and preservation
Hydatothrips volcano Mound & Marullo
No full textHydatothrips volcano Mound & Marullo (Fig. 8) Hydatothrips volcano Mound & Marullo, 1996: 162. Female macroptera. Colour: body mainly brown, tergite VI pale, tergite X yellowish brown also posterior area of metathorax; fore wing brown with pale sub-basal area and paler suffused brown area medially; antennal segment I yellow, II pale, III yellow with apical third light brown, IV yellow on basal half and increasingly darker towards apex, V–VIII brown; femora brown, except apex of fore femora, fore tibiae yellowish brown with brown suffused area medially, mid and hind tibiae brown with apex and base light brown. Structure: Occipital apodeme confluent with posterior margin of eyes (Fig. 8), ocellar area transversely striate with internal markings; pronotum anterior area transversely reticulate with markings between the major lines, blotch distinct; mesonotum transversely striate (Fig. 8), metanotum with transverse striae on anterior half and longitudinal striae on posterior half; fore wing second vein with two setae; posteromarginal comb on tergites II–VI with minute teeth medially, VII with medium-sized teeth medially, VIII complete; tergite IX with 2 pairs of middorsal setae. Sternites III–V and VII without microtrichia medially, VI with a few rows of microtrichia medially. Material studied. Holotype female, COSTA RICA, Braulio Carrillo National Park, Volcan Barba Station (2500 m), on Malaise trap, vi.1990 (BMNH). Comments. The only known specimen of this species was collected from a trap, and there is no further information about its biology. It is similar to H. sternalis, but larger, darker and without microtrichia medially on abdominal sternites.Published as part of Lima, Élison Fabrício B. & Mound, Laurence A., 2016, Species-richness in Neotropical Sericothripinae (Thysanoptera: Thripidae), pp. 1-45 in Zootaxa 4162 (1) on page 9, DOI: 10.11646/zootaxa.4162.1.1, http://zenodo.org/record/26386
Combining model and geostationary satellite data to reconstruct hourly SST field over the Mediterranean Sea
No full textThis work focuses on the reconstruction of Sea Surface Temperature (SST) diurnal cycle through combination of numerical model analyses and geostationary satellite measurements. The approach takes advantage of geostationary satellite observations as the diurnal signal source to produce gap-free optimally interpolated (OI) hourly SST fields using model analyses as first-guess. The resulting SST anomaly field (satellite-model) is free, or nearly free, of any diurnal cycle, thus allowing one to interpolate SST anomalies using satellite data acquired at different times of the day.The method is applied to reconstruct the hourly Mediterranean SST field during summer 2011 using SEVIRI data and Mediterranean Forecasting System analyses. A synthetic cloud reconstruction experiment demonstrated that the OI SST method is able to reconstruct an unbiased SST field with a RMS. = 0.16. °C with respect to SEVIRI observations. The OI interpolation estimate, the model first guess and the SEVIRI data are evaluated using drifter and mooring measurements. Special attention is devoted to the analysis of diurnal warming (DW) events that are particularly frequent in the Mediterranean Sea. The model reproduces quite well the Mediterranean SST diurnal cycle, except for the DW events. Due to the thickness of the model surface layer, the amplitude of the model diurnal cycle is often less intense than the corresponding SEVIRI and drifter observations. The Diurnal OI SST (DOISST) field, resulting from the blending of model and SEVIRI data via optimal interpolation, reproduces well the diurnal cycle including extreme DW events. The evaluation of DOISST products against drifter measurements results in a mean bias of -. 0.07. °C and a RMS of 0.56. °C over interpolated pixels. These values are very close to the corresponding statistical parameters estimated from SEVIRI data (bias. = -. 0.16. °C, RMS. = 0.47. °C). Results also confirm that part of the mean bias between temperature measured by moorings at 1. m depth and the satellite observations can be ascribed to the different nature of the measurements (bulk versus skin). © 2013 Elsevier Inc
NEW EVIDENCES OF TWO DIFFERENT KEY PATHOGENIC MECHANISMS IN HUNTINGTON'S DISEASE
No full textHuntington’s disease (HD) is an adult-onset neurodegenerative disorder characterized by several alterations in critical molecular and cellular pathways. Although genetic and experimental evidence has provided insights into HD pathogenesis, and many hypotheses concerning its underlying mechanisms have been proposed, a treatment that delays disease onset or slows its progression is still missing (Zuccato et al., 2010). During my PhD, my research activity was focused on the investigation of new aspects of two key pathogenic mechanisms of HD: i) the reduction of Brain-Derived Neurotrophic Factor (BDNF) and ii) the cholesterol dysfunction.
Reduced BDNF levels have been described in a number of patho-physiological conditions, most notably, in HD. Since BDNF is also produced in blood, we have undertaken the measurement of its peripheral levels in the attempt to identify a possible link with HD prognosis and/or its progression. In the first part of my PhD, I evaluated BDNF level in 398 blood samples including 138 controls, 56 preHD, and 204 HD subjects. I found that BDNF protein levels were not reliably different between groups, whether measured in plasma (52 controls, 26 preHD, 105 HD) or serum (39 controls, 5 preHD, 29 HD). The analysis of the literature highlighted that intra-group variability and methodological aspects affect this measurement, especially in serum. Moreover during my PhD, I set up a novel strategy for mRNA normalization in quantitative real-time PCR that is based on expressed Alu repeat amplification as a measure for the mRNA fraction. I demonstrated that expressed Alu repeat amplification is a fast, accurate normalization tool that can be successfully used for quantification of selected mRNA in the human transcriptome. This result is particularly important for clinical diagnosis and biomarker validation studies based on mRNA detection in human blood. Based on this new normalization method, I measured BDNF mRNA levels in blood samples from 47 controls, 25 preHD, and 70 HD subjects, and found no differences among the groups. These results indicated that levels of BDNF in human blood were not informative (mRNA levels or plasma protein level) nor reliable (serum protein levels) as HD biomarkers.
Brain cholesterol, which is synthesized locally, is a major component of myelin and cell membranes and participates in several neuronal activities, such as neurite outgrowth and synaptogenesis. In post-natal life, the cholesterol-dependent activities of neurons mainly rely on the transport of cholesterol from astrocytes on ApoE-containing lipoproteins. Mounting evidence indicates that reduced cholesterol biosynthesis occurs in the brain of several models of Huntington’s disease (HD) and is manifest in astrocytes (Valenza et al., J. Neurosci 2010). However, how mutation in huntingtin elicits changes in cholesterol biosynthesis pathway is still unknown. In the second part of my thesis, I explored the cross-talk between neurons and astrocytes to determine whether reduced cholesterol biosynthesis/secretion by HD astrocytes influences cholesterol-dependent properties in wt (and HD) neurons, such as neurite outgrowth and synaptic vesicles formation/maintenance. Primary neurons and astrocytes expressing normal and mutant huntingtin have been used in different experimental settings, in order to evaluate i) the influence of cell non-autonomous mechanisms involving defective cholesterol synthesis/secretion by astrocytes bearing mutant htt and how this dysfunction affects networks and cholesterol-dependent properties of neurons that undergo degeneration in HD; ii) exploring the underlying molecular mechanism of the cholesterol biosynthesis dysfunction in HD astrocytes to identify potential targets of intervention from therapeutic standpoints. I show that glial-derived medium from wt astrocytes (GCMwt) and cholesterol administration improve neurite outgrowth and synaptic properties in wt and HD neurons. The same parameters are not increased after administration of GCM from primary HD astrocytes (GCMHD) or GCMwt depleted of lipoproteins. These findings support the hypothesis that non-cell autonomous mechanisms related to cholesterol and involving astrocytes may contribute to HD pathogenesis. Strategies aimed at selectively modulating brain cholesterol metabolism might be of impact in HD
Molecular “Pincer” from a Diimidazolium Salt: A Study of Binding Ability
No full textThe anion recognition ability of the dicationic imidazolium salt 3,3′-di-n-octyl-1,1′-
(1,3-phenylenedimethylene)diimidazolium 1,5-naphthalenedisulfonate ([m-Xyl-(oim)2][1,5-NDS])
was investigated in acetonitrile solution by means of proton NMR titrations. A wide range of anions,
comprising simple inorganic ions, halides, and mono- and dicarboxylates was taken into account. The
study showed that this receptor binds carboxylate anions more strongly than halides. Moreover [m-
Xyl-(oim)2][1,5-NDS] displays selectivity for di- over monocarboxylate anions. The complex
stability was mainly affected by the anion basicity in the presence of monocarboxylates, whereas the
flexibility of the alkyl chain linking the two carboxylate moieties appeared to play a major role in the
presence of dicarboxylate anions
Thromboembolism leading to myocardial ischemia in a patient requiring a fenestrated Fontan operation.
No full textWe report a case of air/thromboembolism of the left anterior descending coronary artery complicating a fenestrated Fontan procedure treated with aprotinin. The patient was successfully treated by saphenous vein grafting to the left anterior descending coronary artery and reconversion of the Fontan circulation to the original cavo-pulmonary connection
Friendly Training: Neural Networks Can Adapt Data To Make Learning Easier
No full textIn the last decade, motivated by the success of Deep Learning, the scientific community proposed several approaches to make the learning procedure of Neural Networks more effective. When focussing on the way in which the training data are provided to the learning machine, we can distinguish between the classic random selection of stochastic gradient-based optimization and more involved techniques that devise curricula to organize data, and progressively increase the complexity of the training set. In this paper, we propose a novel training procedure named Friendly Training that, differently from the aforementioned approaches, involves altering the training examples in order to help the model to better fulfil its learning criterion. The model is allowed to 'simplify' those examples that are too hard to be classified at a certain stage of the training procedure. The data transformation is controlled by a developmental plan that progressively reduces its impact during training, until it completely vanishes. In a sense, this is the opposite of what is commonly done in order to increase robustness against adversarial examples, i.e., Adversarial Training. Experiments on multiple datasets are provided, showing that Friendly Training yields improvements with respect to informed data sub-selection routines and random selection, especially in deep convolutional architectures. Results suggest that adapting the input data is a feasible way to stabilize learning and improve the generalization skills of the network
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