168 research outputs found
Online Similarity Prediction of Networked Data from Known and Unknown Graphs
No full textWe consider online similarity prediction problems over networked data. We begin by relating this task to the more standard class prediction problem, showing that, given an arbitrary algorithm for class prediction, we can construct an algorithm for similarity prediction with "nearly" the same mistake bound, and vice versa. After noticing that this general construction is computationally infeasible, we target our study to {\em feasible} similarity prediction algorithms on networked data. We initially assume that the network structure is {\em known} to the learner. Here we observe that Matrix Winnow \cite{w07} has a near-optimal mistake guarantee, at the price of cubic prediction time per round. This motivates our effort for an efficient implementation of a Perceptron algorithm with a weaker mistake guarantee but with only poly-logarithmic prediction time. Our focus then turns to the challenging case of networks whose structure is initially {\em unknown} to the learner. In this novel setting, where the network structure is only incrementally revealed, we obtain a mistake-bounded algorithm with a quadratic prediction time per round
Combined effects of salinity and chlorpyrifos on the earthworm Eisenia andrei
No full textSoil salinization could represent a threat for earthworms, affecting their general health status, reproduction and survival. This stressing condition could be worsened by the presence of further anthropic factors, like pesticides, whose effect may be exacerbated in a climate change scenario. Hence the goal of this study was to evaluate the effects of salinity (SAL), chlorpyrifos (CP) and their combination on the earthworm Eisenia andrei. Five different SAL conditions (0.1 ÷ 12 g/L), and five different CP concentrations (3.16 ÷ 316 mg/kg) were tested in “single stressor” experiments. Seventeen different combinations (SAL 2.5 ÷ 10 g/L; CP 5 ÷ 80 mg/kg) were tested in the following “combination” experiment. The endpoints considered were mortality, growth, reproduction and acetylcholinesterase (AChE) activity. Exposure to SAL decreased growth, survival and reproduction of earthworms, especially at the highest salt concentrations, where no cocoons were found at the end of the experiment. CP affected survival and growth only at the highest concentration, where 100% mortality was observed. Contrariwise, reproduction was affected also at lower concentrations of CP. AChE activity was drastically inhibited by increasing CP concentrations. In the combination experiment, neither SAL nor CP affected worm survival. Growth and number of laid cocoons were reduced by both stress factors, with no interactive effects. Number of juveniles showed a hormetic response to CP in the absence of SAL. Interestingly, SAL eliminated the hormesis. AChE activity was affected only by CP, and not by SAL. In conclusion, combination experiments showed that E. andrei life cycle traits were negatively affected by soil SAL, and also by CP at high concentrations. AChE activity was very sensitive to CP, while it was not affected by SAL. The number of juveniles was the only endpoint showing interactive effects between the two stress factors
Efectos de la transición nutricional en adolescentes escolarizados de nivel secundario de Córdoba (Argentina)
No full textFil: Pasteris, María Victoria. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Carrera de Ciencias Biológicas; Argentina.El sobrepeso y la obesidad han sido definidos por la OMS como la acumulación anormal o
excesiva de grasa que puede ser perjudicial para la salud, y es reconocida actualmente como la
pandemia más importante, en términos sanitarios, del siglo XXI. Para este estudio se
seleccionaron 4 colegios de nivel secundario, de la ciudad de Córdoba, Argentina, de diferentes
niveles socioeconómicos. Se realizaron comparaciones entre ellos y con las referencias
nacionales (SAP) e internacionales (OMS), en cuanto a talla/edad e IMC/edad; también se
realizaron comparaciones entre los establecimientos para determinar similitudes y diferencias
en cuanto al estado nutricional y analizar la relación entre este y los patrones de alimentación,
condiciones socio económicas y estilos de vida. Además, se utilizó el método LMS para ajustar
datos antropométricos y obtener estándares de percentilos normalizados teniendo en cuenta el
coeficiente de curtosis (L), la mediana (M) y el coeficiente de variación (S). Los datos de
talla/edad e IMC/edad, se ajustan a lo establecido por las referencias nacionales e
internacionales. Si bien los mayores niveles de obesidad se presentan en los colegios con nivel
socioeconómico bajo y medio bajo, el exceso de peso (sobrepeso y obesidad) está presente en
todos los colegios, más allá del nivel socioeconómico. La variable ambiental que estaría más
asociada al exceso de peso es la exposición a pantallas en un rango de 4 a 6 horas diarias.Fil: Pasteris, María Victoria. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Carrera de Ciencias Biológicas; Argentina
Survey of microarthropods and biological quality of soils of San Vitale pinewood (Ravenna, Italy): first results / Etude sur les microarthropodes et sur la qualite biologique des sols de la pinede de San Vitale (Ravenna, Italie): premiers resultats / Indagine sui microartropodi e sulla qualità biologica dei suoli della pineta di San Vitale (Ravenna, Italia): primi risultati
No full textSono riportati i primi risultati di uno studio condotto nella Pineta di San Vitale (Ravenna). L'obiettivo è valutare la qualità biologica dei suoli mediante l’analisi del popolamento dei microartropodi edafici, in relazione al pedotipo ed in particolare alla salinizzazione. La Qualità Biologica del Suolo è valutata con l’indice QBS-ar.
La Pineta è stata campionata nella zona Est, maggiormente influenzata dall’ingressione salina e nella zona Ovest, dove tale fenomeno è meno rilevante. Il campionamento è stato svolto in primavera e in estate. I risultati del campionamento primaverile, confermano che le caratteristiche chimiche e fisiche variano secondo il gradiente sommità dunali - bassure interdunali. Per quanto riguarda la struttura del popolamento di microartropodi e il QBS-ar, si riconoscono alcune caratteristiche comuni alla maggior parte delle stazioni con il medesimo pedotipo. Non si evidenzia uno stress sul popolamento attribuibile alla salinizzazione. Il QBS-ar è nel complesso abbastanza elevato
Toxicity of hexavalent chromium to the earthworm Eisenia andrei: linking effects at different levlels of biological organization
No full textLiving organisms respond to chemicals at all the levels of biological organization, from molecules to ecosystems. In general, biochemical and physiological responses (molecules, cells, tissues) are triggered at low concentrations and after short exposure times, while ecological responses (life cycle traits, populations, communities, ecosystems) can be evidenced only at higher concentrations and after longer exposures. On the other hand, responses at the higher levels of organization are considered more relevant from an environmental point of view, as they often result in irreversible severe damage to ecological systems. It is important to clarify the relationship between low-level and high-level responses to different toxicants, particularly considering the increasing application of biomarkers as early warning systems to assess environmental pollution.
In accordance with this view, effects of exposure to hexavalent chromium, Cr(VI), on life cycle endpoints were compared to effects on a battery of eight biomarkers in the earthworm Eisenia andrei. In spite of the importance of Cr(VI) as an environmental contaminant, its toxicity to earthworms, a major component of soil fauna, has received little attention; in particular almost no data are available on biochemical and physiological responses.
A natural clayey soil was spiked at six Cr(VI) concentrations, from 6.25 to 200 mg/kg. Adult worms were exposed in laboratory to the spiked soils and to a control treatment (unspiked soil). Two sets of experimental containers were prepared: the first to measure lysosomal membrane stability, lysosomal lipofuscins and neutral lipids accumulation, metallothionein content, Ca2+ ATPase, catalase, glutathione S-transferase and acyl CoA oxydase activities, after 10 d of exposure; the second to asses survival, growth and chromium bioaccumulation after 28 d, and reproduction after 56 d of exposure.
All the biological effects were significantly affected by Cr(VI) exposure and showed a clear concentration-effect relationship, except for the content of metallothioneins. Biomarkers showed different trends at increasing Cr(VI) concentrations, that could be classified as typical “increasing responses” (neutral lipids), “decreasing responses” (lysosomal membrane stability, Ca2+-ATPase and acyl Co-A oxydase activities) and “bell-shaped responses” (catalase and glutathione S-transferase activities). Biomarkers were more sensitive to Cr(VI) than life-cycle endpoints; among these, reproduction was the most responsive
The effect factor for nano TiO2: preliminary toxicity tests on Daphnia magna and future developments
No full textNanotechnologies are being developed for application in a large variety of sectors, from food industry to environmental remediation technology. However, numerous uncertainties exist regarding their possible impacts on the environment and human health. The Life Cycle Assessment (LCA) methodology could be a tool to evaluate, analyze and manage the environmental and health effects for the emerging technologies. The evaluation of the environmental performance of nanotechnologies trough LCA is not always possible due to the lack of data regarding the environmental pathway of NPs. The focus of the present research is to evaluate the freshwater ecotoxicological Effect Factor (EF) for TiO2 nanoparticles (which are widely used in different applications as sunscreens, solar cells, ecc.), following the framework of the USEtox model. This model is used for the Life Cycle Impact Assessment (LCIA) phase and is aimed to provide the Characterization Factor (CF) for the ecotoxicity impact category. The CF is quantified trough the evaluation of the Fate Factor (FF) and Effect Factor (EF). The latter is based on chronic or acute toxicity value as EC50. In order to establish the acute EC50 for nano TiO2, two preliminary toxicity tests on Daphnia magna (72h) have been performed. The particles were prepared following two different treatments. In the first case the nano TiO2 suspensions were stirred for 24 h only before the test; in the second case the particles were maintained in agitation also for the whole duration of the bioassay. No adverse effects have been observed for the concentration applied, this contrasts with the findings of other studies that reported effects of nano TiO2 on D. magna. The future developments of our research are to conduct other toxicity tests on D. magna, following different treatments of the sample (example: irradiation with UV-A, filtration etc), and to conduct toxicity test on different trophic level (algae, crustaceans, fish) as suggested by USEtox framework. The research is intended to identify suitable treatments for nanoparticles to be used in toxicity test, taking into account their tendency to aggregate and precipitate and that this could influence the results of the tests. The suitable treatment should also reproduce the actual exposure modality of the organisms in the field
Spontaneous regression of locally advanced pleomorphic dermal sarcoma of the forehead: a case report
No full textWe describe a singular case in which the patient underwent wide surgical excision of the primary lesion (Pleomorphic Dermal Sarcoma) and reconstruction with a skin graft. After seventy-five days, total clinical and radiological regression of the ipsilateral parotid and neck localizations was observed without the need for adjuvant therapy
Urease Inhibitory Potential and Soil Ecotoxicity of Novel "polyphenols-Deep Eutectic Solvents" Formulations
No full textNew formulations based on red grape pomace polyphenols and deep eutectic solvents (DES) have been here evaluated as inhibitors of urease of agricultural interest (jack bean urease, JBU). DES based on choline chloride (CHO) and betaine (BET), combined with ethylene glycol (EG), citric acid (CA), and urea (U), were used both as extracting and carrying agents for polyphenols, becoming active components of the formulations here obtained. Among the various DES combinations, U- and CA-based ones gave the best polyphenol extraction performances, 1.2-1.4-times higher than those of the hydroalcoholic mixture. Among the various DES-polyphenols formulations, the one composed by CHO-EG showed the best antioxidant potential and urease inhibition: 60-90% inhibition of the total JBU activity was achieved with a CHO concentration of 5-20 mM. Good results were also achieved with the BET-EG polyphenol formulation, which was able to inhibit ca. 50% of urease activity at 20 mM concentration of BET. Low phytotoxicity of DES and their polyphenol formulations tested at a concentration of 34 mM of CHO or BET was here observed on cress seedlings and the early growth of oat, in particular, for EG-based DES. On the other hand, tests performed on earthworms showed that CHO-based DES could impair the reproduction, and U-based DES caused severe mortality
Effects of Soil salinization on the earthworm Eisenia andrei: life cicle traits and histochemical biomarkers
No full textSalinisation is the process that leads to an excessive increase of water-soluble salts in the soil, and one of the most widespread soil degradation processes. Along the Adriatic Coast of the Emilia-Romagna region in Italy, our area of interest, soil salinisation is enhanced by salt water seepage, caused among others by subsidence and drainage. Salt prevents, limits or disturbs the normal metabolism and nutrient uptake of plants and other soil biota. Biological effects on plants, in particular crop species, are widely studied because of the socio-economical consequences of agricultural soil loss. Impacts on soil fauna are less known, in spite of its importance in determining soil fertility. Salinity might cause a decreased resistance of organisms to other stressors, eventually leading to synergistic effects. Here we report the results of a laboratory experiment that is intended as a first step of an ongoing study on the interactive effects of soil salinity and pesticide contamination on the earthworm Eisenia andrei. A natural silty soil was collected in the field, dried, grounded and sieved through a 2 mm mesh, to eliminate skeleton. Glass containers (223x121 mm, h: 77 mm) were used as experimental chambers; in each container 500 g of dry soil were mixed with 150 ml of spiking solution (NaCl dissolved in distilled water). A control treatment (distilled water) and five NaCl concentrations ranging from 0.1 to 12 g/L were prepared. Each treatment was replicated in two containers. Ten adult worms for each container were incubated in the experimental soils at controlled environmental conditions (20°C, 400-800 lux, 16 h light/8 h dark). After 28 days ofexposure, three life cycle endpoints were assessed: survival, growth, and reproduction (number of laid cocoons). In addition, three histochemical biomarker were determined: lysosomal membrane stability (neutral red retention assay), lipofuscin and neutral lipid accumulation. Soil salinity had significant adverse effects on all the life cycle endpoints, and it was possible to obtain preliminary estimates of effective median concentration (survival: 10±1 g/L, growth: 8±2 g/L, reproduction: 4 g/L). Soil salinisation did not alter the response of the biomarkers analysed in the present work. Although the biomarker sensitivity to pollutants is reported higher that that of life cycle endpoints, it appears they are not impaired by salinity and may be used for future investigations on polluted salinised soils. As an overall, our study indicates that adverse effects on earthworms are possible at levels of soil salinisation still compatible with agricultural land use, even in the absence of other stressors
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