1,721,242 research outputs found
Water and sodium imbalance in COPD patients
Full text linkWater and sodium imbalance in COPD patients. G. Valli, A. Fedeli, R. Antonucci, P. Paoletti, P. Palange. Water retention and hyponatraemia are typically observed in the final stages of Chronic Obstructive Pulmonary Disease (COPD) and the onset of edema is a poor prognostic factor. For several years the pathogenesis of edema in COPD patients was attributed to heart impairment because of pulmonary hypertension, but the evidence that cardiac output is often adequate for the metabolic demands has suggested, since 1960, that the pathogenesis of edema in these patients would be correlated with gas exchange impairment and in particular with carbon dioxide (CO2) retention. The gas exchange impairment induces, in these patients several hormonal abnormalities: renin (Rn), angiotensin II (AnII), aldosterone (Ald), atrial natriuretic peptide (ANP), vasopressin (ADH) and endothelial factors are some of the factors involved. The systemic response to hypercapnia has the effect of reducing the renal blood flow and, as a result, increasing water and sodium retention with the final effect of edema and hyponatraemia. The aim of this brief review is to highlight the current knowledge on renal /hormonal abnormalities in COPD and their therapeutic implications
Ozone assessment in the Southern part of the Alps
No full textIn this paper ozone measurements carried out at six alpine and prealpine sites, located in the Italian region of Central Alps are shown. The stations are placed at altitudes between 800 and 1900 m a.s.l., far away from local sources of pollution. Ozone concentrations appear to be quite uniform, with summer mean values varying from 40 to 47 ppb and winter ones from 19 to 35 ppb. The number of hours exceeding the 75 and 100 ppb WHO thresholds and the AOT40 (Average Over Threshold 40 ppb of ozone) are evaluated for the growing season. The temporal variability of weekly ozone cycle at alpine stations provides useful informations to assess an emission control strategy
Ozone measurements in atmosphere and correlations with Be-7 in an Italian alpine valley
No full textSince 1990 our Institute has been conducting Be-7 measurements in the atmosphere in order to use it as a tracer for air coming from the upper layers of the atmosphere and for the stratospheric ozone. In this paper we present the results on Be-7 measurements and ozone concentrations obtained with a one-year monitoring campaign carried out in Sondrio, an alpine town in Northern Italy. For a few interesting events correlations between beryllium and ozone is observed. Be-7 reveals itself as a good marker which reaches ground level during particularly rare events such as stratospheric intrusions
OSLVQ: a training strategy for optimum-size learning vector quantization classifiers
No full textIn this paper we describe OSLVQ (Optimum-Size Learning Vector Quantization), an algorithm for training learning vector quantization (LVQ) classifiers that achieves effective sizing of networks through a multi-step procedure. In each step of the algorithm the network is first trained with a few iterations of one of the LVQ algorithms. After this partial training the structure of the network is updated according to the performances achieved in classifying the training set: we add neurons whose weight vectors are enclosed in regions of the pattern space where several misclassified patterns are found, while we remove neurons which are activated by too few training patterns. Neurons are also removed if their presence is redundant, i.e. when, in their absence, other neurons representing the same class would respond to the same patterns. Results obtained on a set of patterns representing phonemes are reported and compared with the ones achieved by a standard-LVQ classifier of similar size
A study on nighttime-daytime PM10 concentration and elemental composition in relation to atmospheric dispersion in the urban area of Milan (Italy)
No full textIn this paper, results on a PM10 daytime–nighttime measurement campaign carried out in Milan to study the evolution of PM10 concentration and composition in relation to atmospheric dispersion conditions are shown. To account for the evolution of atmospheric dispersion conditions, Radon hourly concentration measurements were performed. The significant correlation between PM10 and 222Rn daytime concentrations evidences the dominant role of atmospheric dispersion in determining the temporal variation of PM10 levels. Whenever 222Rn concentrations accumulate during the night (indicating the formation of nocturnal atmospheric stability conditions), PM10 concentrations are higher than those registered during the daytime before, despite a decrease in emissions from active sources. On the contrary, when 222Rn concentrations do not accumulate during night hours, PM10 levels are lower than those measured during the daytime before.
As concerns the average elemental concentrations (in ng m−3), the nighttime–daytime variations are in the range −17% to +37%; during the night, soil-related elements (Al, Si, Ca, Ti) decrease while anthropogenic elements (Zn, Cu, Fe, Pb) increase.
A case study concerning a ‘green’ Sunday (when traffic was forbidden from 8 a.m. to 8 p.m.) is also discussed. The difference of PM10 concentration and elemental composition registered during the ‘green’ Sunday daytime and the following nighttime, together with the information on atmospheric dilution power obtained by Radon measurements, allowed the characterisation of the traffic source elemental profile and increased the comprehension of the low effectiveness of some PM10 reduction strategies
Seasonal variation of Pb-210 activity concentration in outdoor air of Milan (Italy)
No full textWeekly measurements of 210Pb activity concentration on aerosol particles were performed at ground level in outdoor air in Milan (Italy) during the years 2000-2001. The experimental method was based on the delayed alpha spectrometry of in-grown 210Po activity detected on airborne particles collected on a filter support. On the same filter the 214Pb activity concentration was also measured during the sampling. 210Pb weekly concentration values showed a great variability and the average monthly values exhibited a seasonal pattern characterised by maxima in winter and minima in spring-summer. The same seasonal trend was also observed in 214Pb concentration values. 210Pb average yearly values were 0.70 and 0.82 mBq/m3 in 2000 and 2001, respectively, in good agreement with literature data registered at continental sites of similar latitude and longitude. The activity ratio 210Pb/214Pb was used to evaluate the residence time of fine aerosols in the urban air of Milan, which was 1-2 days
Energy dispersive X-ray fluorescence analysis applied to biomonitoring on Alps
No full textThe results of a research in progress at the Istituto di Fisica Generale Applicata-University of Milan-on natural and anthropogenic elements' determination in mosses as biological indicators are shown. The analytical technique was the energy dispersive X-ray fluorescence (EDXRF) spectrometry. The chosen areas for a preliminary pollution mapping were Italian Central Alps (Valmalenco and Valtellina) and the hills around Come (pre-Alps); in addition, a group of mosses was from Monza Park, near Milan
Be-7 in surface air : a natural atmospheric tracer
No full textSince 1989 our Institute had been monitoring Be-7 to use it as a natural tracer of air masses coming from the upper layers of the atmosphere. In this paper Be-7 measurements carried out by our Institute in the last years are shown. The atmospheric particulate sampling was performed daily at ground level and Be-7 activities were obtained by means of gamma-spectrometry
Factors influencing mass concentration and chemical composition of fine aerosols during a PM high pollution episode
No full textResults obtained during a winter field campaign for the fine fractions of particulate matter are presented. A high pollution episode together with an analysis of the main factors, which influence accumulation of pollutants is described. The measurement campaigns were carried out simultaneously at two sites in Northern Italy, Milan and Erba, during the winter of 2000. The daily variability in the mass concentration values and PM2.5/PM10 ratios appeared to be strongly dependent upon meteorological and atmospheric stability conditions and, in particular, wind regimes. During the intensive field campaign a high-pollution episode occurred that led to TSP and fine fraction concentrations well above the attention and alarm thresholds, reaching values of up to 200–250 μg m−3. The elemental concentrations were determined by ED-XRF analysis. The elemental composition of the particulate matter indicated that crustal matter oxides (soil dust) were the main component in particles with aerodynamic diameter dae>10 μm. They were an important part also in particles with 2.5<dae<10 μm, but strongly decreased in particles with dae<2.5 μm. In the finer fraction sulphates nitrogen and carbon compounds played a major role. The temporal patterns of mass and elemental concentrations, as well as the main components of PM were very similar at the two sites. The high-pollution episode was recorded at many locations in the Po plain, highlighting the role of meteorology and thermodynamic atmospheric conditions on pollution build-up on a large area
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