Search results for "Threshold limit value"

Exposure to bioaerosols and noise at a Finnish dry waste treatment plant

2004

Repeated measurements were carried out during two different campaigns between 1998 and 2001 to assess the occupational hygiene at a Finnish dry waste treatment plant. The analytical determinations were done in four different places within the processing hall of the plant: near a conveyor belt, near a jigger screen, near an after-crusher and near a bailer. Measurements were also carried out in a coffee room for employees. Concentrations of bacteria, fungi and actinomycetes were determined by two methods (six-stage impactor and Camnea method) and levels of endotoxins, dust and noise were also investigated. High concentrations of microbes and endotoxins and the noise level were found to be a …

Microbial environmental contamination in Italian dental clinics: A multicenter study yielding recommendations for standardized sampling methods and t…

2012

A microbiological environmental investigation was carried out in ten dental clinics in Italy. Microbial contamination of water, air and surfaces was assessed in each clinic during the five working days, for one week per month, for a three-month period. Water and surfaces were sampled before and after clinical activity; air was sampled before, after, and during clinical activity. A wide variation was found in microbial environmental contamination, both within the participating clinics and for the different sampling times. Before clinical activity, microbial water contamination in tap water reached 51,200cfu/mL (colony forming units per milliliter), and that in Dental Unit Water Systems (DUWS…

Microtremor Measurements in the City of Palermo, Italy: Analysis of the Correlation between Local Geology and Damage

2008

Abstract This study presents the results of 90 seismic ambient noise measurements in Palermo, the main city of Sicily (Italy). The dataset has been processed using the horizontal-to-vertical spectral ratio (HVNSR) technique and interpreted in terms of local geology, which is characterized by the presence of alluvial sediments of two riverbeds masked by urbanization since the seventeenth century. HVNSRs show significant variations in the study area: when the transition stiff to soft is crossed, a typical spectral peak appears in the HVNSRs, mostly in the frequency band 1–2 Hz, and exceeding a factor of 3 in amplitude. Using available information on subsurface geological structure, we compute…

Predicting unit plot soil loss in Sicily, south Italy

2008

Predicting soil loss is necessary to establish soil conservation measures. Variability of soil and hydrological parameters complicates mathematical simulation of soil erosion processes. Methods for predicting unit plot soil loss in Sicily were developed by using 5 years of data from replicated plots. At first, the variability of the soil water content, runoff, and unit plot soil loss values collected at fixed dates or after an erosive event was investigated. The applicability of the Universal Soil Loss Equation (USLE) was then tested. Finally, a method to predict event soil loss was developed. Measurement variability decreased as the mean increased above a threshold value but it was low als…

Predicting rainfall erosivity by momentum and kinetic energy in Mediterranean environment

2018

Abstract Rainfall erosivity is an index that describes the power of rainfall to cause soil erosion and it is used around the world for assessing and predicting soil loss on agricultural lands. Erosivity can be represented in terms of both rainfall momentum and kinetic energy, both calculated per unit time and area. Contrasting results on the representativeness of these two variables are available: some authors stated that momentum and kinetic energy are practically interchangeable in soil loss estimation while other found that kinetic energy is the most suitable expression of rainfall erosivity. The direct and continuous measurements of momentum and kinetic energy by a disdrometer allow als…

Acute exposure to 50ppm toluene does not increase sleepiness

2005

Abstract The Pupillographic Sleepiness Test (PST) is a new neurophysiological method to assess sleepiness. In an exposure study to a constant exposure level of 50 ppm toluene on 20 healthy men, our aim was to find out, if increased sleepiness could be seen with PST. PST was performed before and after 4.5 h of exposure. General complaints were assessed with the Swedish Performance Evaluation System (SPES) self-assessment questionnaire, once before and during exposure. Values obtained during exposure were related to pre-exposure values. Parametric cross-over analysis of logarithmic Pupillary Unrest Index (PUI) values did not show an effect of toluene exposure. In a nonparametric cross-over an…

Modelling bioconcentration of pesticides in fish using biopartitioning micellar chromatography.

2005

Ecotoxicity assessment is essential before placing new chemical substances on the market. An investigation of the use of the chromatographic retention (log k) in biopartitioning micellar chromatography (BMC) as an in vitro approach to evaluate the bioconcentration factor (BCF) of pesticides in fish is proposed. A heterogeneous set of 85 pesticides from six chemical families was used. For pesticides exhibiting bioconcentration in fish (experimental log BCF > 2), a quantitative retention-activity relationships (QRAR) model is able to perform precise log BCF estimations of new pesticides. Considering the present data, the results based on log k seem to be more reliable than those from availabl…

2016

Abstract. Various geoscientific applications require a fast prediction of fracture permeability for an optimal workflow. Hence, the objective of the current study is to introduce and validate a practical method to characterize and approximate single flow in fractures under different stress conditions by using a core-flooding apparatus, in situ X-ray computed tomography (CT) scans and a finite-volume method solving the Navier–Stokes–Brinkman equations. The permeability of the fractured sandstone sample was measured stepwise during a loading–unloading cycle (0.7 to 22.1 MPa and back) to validate the numerical results. Simultaneously, the pressurized core sample was imaged with a medical X-ray…

Methods for evaluating causality in observational studies.

2019

BACKGROUND: In clinical medical research, causality is demonstrated by randomized controlled trials (RCTs). Often, however, an RCT cannot be conducted for ethical reasons, and sometimes for practical reasons as well. In such cases, knowledge can be derived from an observational study instead. In this article, we present two methods that have not been widely used in medical research to date. METHODS: The methods of assessing causal inferences in observational studies are described on the basis of publications retrieved by a selective literature search. RESULTS: Two relatively new approaches—regression-discontinuity methods and interrupted time series—can be used to demonstrate a causal relat…

Feature Selection Approach based on Mutual Information and Partial Least Squares

2014

Feature selection technology can improve the modeling accuracy and reduce model’s complexity, especially for the high dimensional spectral data. Aim at this problem, feature selection approach based on mutual information (MI) and partial least square (PLS) is proposed in this paper. MI values between features and responsible variable are calculated, and the threshold value using to select final features is optimal selected based on PLS algorithm. The numbers of the latent values of the PLS and the threshold value of MI are selected according the modeling performance simultaneously. The experimental results based on the near-infrared spectrum show that the proposed approach has better perfor…