250 research outputs found
Static locality analysis for cache management
Most memory references in numerical codes correspond to array references whose indices are affine functions of surrounding loop indices. These array references follow a regular predictable memory pattern that can be analysed at compile time. This analysis can provide valuable information like the locality exhibited by the program, which can be used to implement more intelligent caching strategy. In this paper we propose a static locality analysis oriented to the management of data caches. We show that previous proposals on locality analysis are not appropriate when the proposals have a high conflict miss ratio. This paper examines those proposals by introducing a compile-time interference analysis that significantly improve the performance of them. We first show how this analysis can be used to characterize the dynamic locality properties of numerical codes. This evaluation show for instance that a large percentage of references exhibit any type of locality. This motivates the use of a dual data cache, which has a module specialized to exploit temporal locality, and a selective cache respectively. Then, the performance provided by these two cache organizations is evaluated. In both organizations, the static locality analysis is responsible for tagging each memory instruction accordingly to the particular type(s) of locality that it exhibits.Peer ReviewedPostprint (published version
EMISSION AND ATMOSPHERIC IMPACT OF A CUBAN REFINERY
In the processes of an oil refinery, considerable emissions of atmospheric pollutants are
generated that produces hazard to mans health and the environment. In this study, the
obtained results of the characterization of the gaseous emissions by chimneys of the furnaces
and boilers of the refinery are presented. The sampling and analysis of SO2, NOX, CO,
total suspended particles, and flow measurements were carried out. The aromatic
hydrocarbons were determined by UV Spectroscopy. The model of dispersion of pollutants
emitted by chimneys was executed using the software for the calculation of the gas
concentration from continuous industrial sources following the methodology approved in
the Cuban standards, according to the Berliand Model. We conclude that the combustion
processes of the Refinery reflect a fault, given the particles emissions. The emissions of
the furnaces and boilers exert negative impact or pressure on the atmospheric environment
in the area
Smelling Nano Aerial Vehicle for Gas Source Localization and Mapping
This paper describes the development and validation of the currently smallest aerial platform with olfaction capabilities. The developed Smelling Nano Aerial Vehicle (SNAV) is based on a lightweight commercial nano-quadcopter (27 g) equipped with a custom gas sensing board that can host up to two in situ metal oxide semiconductor (MOX) gas sensors. Due to its small form-factor, the SNAV is not a hazard for humans, enabling its use in public areas or inside buildings. It can autonomously carry out gas sensing missions of hazardous environments inaccessible to terrestrial robots and bigger drones, for example searching for victims and hazardous gas leaks inside pockets that form within the wreckage of collapsed buildings in the aftermath of an earthquake or explosion. The first contribution of this work is assessing the impact of the nano-propellers on the MOX sensor signals at different distances to a gas source. A second contribution is adapting the 'bout' detection algorithm, proposed by Schmuker et al. (2016) to extract specific features from the derivative of the MOX sensor response, for real-time operation. The third and main contribution is the experimental validation of the SNAV for gas source localization (GSL) and mapping in a large indoor environment (160 m²) with a gas source placed in challenging positions for the drone, for example hidden in the ceiling of the room or inside a power outlet box. Two GSL strategies are compared, one based on the instantaneous gas sensor response and the other one based on the bout frequency. From the measurements collected (in motion) along a predefined sweeping path we built (in less than 3 min) a 3D map of the gas distribution and identified the most likely source location. Using the bout frequency yielded on average a higher localization accuracy than using the instantaneous gas sensor response (1.38 m versus 2.05 m error), however accurate tuning of an additional parameter (the noise threshold) is required in the former case. The main conclusion of this paper is that a nano-drone has the potential to perform gas sensing tasks in complex environments
3D Gas distribution with and without artificial airflow: An experimental study with a grid of metal oxide semiconductor gas sensors
Occurrence of selected viral and bacterial pathogens and microbiological quality of fresh and frozen strawberries sold in Spain
Strawberry production and exports have been increasing in Spain in recent decades. However, little information is available about their microbiological quality. Due to the growing concern about the microbial safety of these fruits, the objective of this investigation was to study the microbiological quality and the prevalence of the main foodborne pathogens on strawberries sold in Spain. Fresh (n = 152) and frozen (n = 31) samples were obtained from marketplaces and fields in 2017 and 2018. The samples were assayed for total aerobic mesophilic microorganisms (TAM), moulds and yeasts (M&Y), total coliforms (TC), Escherichia coli, Salmonella spp., Listeria monocytogenes as well as Norovirus (NoV) GI and GII. The microbiological counts ranged from <1.70 (detection limit, dl) – 5.89 log10 CFU/g (mean 3.78 log10 CFU/g) for TAM; 2.10–5.86 log10 CFU/g (mean 3.80 log10 CFU/g) for M&Y; and <0.70 (dl) – 4.91 log10 CFU/g (mean 2.15 log10 CFU/g) for TC in fresh strawberries. In frozen strawberries, the counts were <1.70 (dl) – 3.66 log10 CFU/g (mean 2.30 log10 CFU/g) for TAM; <1.70 (dl) – 2.76 log10 CFU/g (mean 1.82 log10 CFU/g) for M&Y; and <0.70(dl) – 1.74 log10 CFU/g (mean 0.77 log10 CFU/g) for TC. All the samples in this study tested negative for Salmonella spp., L. monocytogenes. E. coli and NoV GI and GII genome. A global overview of all the data was executed using Principal Component Analysis (PCA), and the results showed that the scores and loadings according to principal components 1 (PC1) and 2 (PC2) accounted for 75.9% of the total variance, allowing a distinction between fresh and frozen samples. The presence of moulds was significantly higher in the supermarket samples whereas the presence of total coliforms was significantly higher in the field samples (p < 0.05). Although pathogenic microorganisms were not found, preventative measures and prerequisites in the strawberry production chain must be considered in order to avoid possible foodborne diseases related to the microbiological quality of the fruit.info:eu-repo/semantics/acceptedVersio
BLE-GSpeed: A new BLE- based dataset to estimate user gait speed
To estimate the user gait speed can be crucial in many topics, such as health care systems,
since the presence of difficulties in walking is a core indicator of health and function in aging and
disease. Methods for non-invasive and continuous assessment of the gait speed may be key to
enable early detection of cognitive diseases such as dementia or Alzheimer’s disease. Wearable
technologies can provide innovative solutions for healthcare problems. Bluetooth Low Energy (BLE)
technology is excellent for wearables because it is very energy efficient, secure, and inexpensive.
In this paper, the BLE-GSpeed database is presented. The dataset is composed of several BLE RSSI
measurements obtained while users were walking at a constant speed along a corridor. Moreover,
a set of experiments using a baseline algorithm to estimate the gait speed are also presented to
provide baseline results to the research community
Clinical and anatomopathological features of eosinophilic oesophagitis in children and adults
Introduction: Eosinophilic oesophagitis (EoE) is a chronic clinical-pathological disorder with an immunological basis characterised by symptoms of oesophageal dysfunction and, histologically, eosinophilic inflammation.
Objective: To evaluate the clinical characteristics and differences in children and adults diagnosed with EoE in a tertiary level hospital.
Method: Descriptive, retrospective and cross-sectional study. We randomly selected 40 children and 40 adults diagnosed with EoE between 2009 and 2016. The patient characteristics were analysed by means of epidemiological, clinical, diagnostic and therapeutic variables.
Results: The average age at diagnosis was 10 years (children) and 34 years (adults), with a higher frequency in males. The majority were sensitised to aeroallergens (77.5% children vs. 82.5% adults) and foods (75% children vs. 82.5% adults). Statistically significant differences were detected in sensitisation to fruits (p = 0.007) and grains (p < 0.001). Differences were observed in impaction (22.5% children vs. 82.5% adults), dysphagia (42.5% children vs. 77.5% adults) and abdominal pain (25% children vs. 7.5% adults). Endoscopy showed that children had a higher frequency of exudates (92.5%) and adults, trachealisation (50% vs. 5%) and stenosis (17.5% vs. 2.5%). Statistically significant differences were found in treatment with topical corticosteroids (30% children vs. 77.5% adults), with a variable positive response. 77.5% of the patients received elimination diets.
Conclusions: Statistically significant differences were observed between the paediatric and adult populations in the food sensitisation profiles, clinical manifestations, endoscopic findings and treatments received. This is a complex pathology that calls for a multidisciplinary team and would require new non-invasive techniques to facilitate its management
La enseñanza universitaria apoyada en plataformas virtuales. Cambios en las prácticas docentes: el caso de la Universidad de Sevilla
El estudio de los usos de las plataformas virtuales
en la enseñanza universitaria constituye hoy un
referente de interés para la docencia. El objetivo de esta
investigación es explorar los usos pedagógicos de estas
herramientas, con la finalidad de identificar factores
condicionantes y sus variables asociadas. Esta investigación,
que analiza el caso de la Universidad de Sevilla,
se basa en un estudio descriptivo, tipo encuesta. Los resultados
obtenidos permiten establecer como conclusiones
relevantes que las prácticas de enseñanza online
están mediadas por las concepciones y creencias
pedagógicas del profesorado; pero a su vez los usos tecnológicos
influyen y transforman dichas concepcione
Evaluation of a sanitizing washing step with different chemical disinfectants for the strawberry processing industry
Strawberries are often consumed fresh or only receive minimal processing, inducing a significant health risk to the consumer if contamination occurs anywhere from farm to fork. Outbreaks of foodborne illness associated with strawberries often involve a broad range of microbiological agents, from viruses (human norovirus) to bacteria (Salmonella spp. and Listeria monocytogenes). The addition of sanitizers to water washes is one of the most commonly studied strategies to remove or inactivate pathogens on berries as well as avoid cross contamination due to reuse of process wash water. The risk posed with the safety issues of by-products from chlorine disinfection in the fruit industry has led to a search for alternative sanitizers. We evaluated the applicability of different chemical sanitizers (peracetic acid (PA), hydrogen peroxide (H2O2), citric acid (CA), lactic acid (LA) and acetic acid (AA)) for the inactivation of S. enterica, L. monocytogenes and murine norovirus (MNV-1) on strawberries. A control treatment with chlorine (NaClO) (100 ppm) was included. For each sanitizer, different doses (40, 80 and 120 ppm for PA and 1, 2.5 and 5% for H2O2, LA, AA and CA) and time (2 and 5 min) were studied in order to optimize the decontamination washing step. The best concentrations were 80 ppm for PA, 5% for H2O2 and 2.5% for organic acids (LA, AA and CA) after 2 min treatment. Results indicate that the sanitizers selected may be a feasible alternative to chlorine (100 ppm) for removing selected pathogenic microorganisms (P > 0.05), with reductions about ≥2 log for bacterial strains and ≥ 1.7 log for MNV-1. As the washing water may also increase the microbial counts by cross-contamination, we observed that no pathogenic bacteria were found in wash water after 5% H2O2 and 80 ppm PA after 2 min treatment. On the other hand, we also reported reductions about total aerobic mesophyll (TAM) (0.0–1.4 log CFU/g) and molds and yeasts (M&Y) (0.3–1.8 log CFU/g) with all alternative sanitizers tested. Strawberries treated did not shown significant differences about physio-chemical parameters compared to the untreated samples (initial). For this study, the optimal sanitizer selected was PA, due to the low concentration and cost needed and its microbiocidal effect in wash water and fruit. Notwithstanding the results obtained, the effect of PA in combination with other non-thermal technologies such as water-assisted ultraviolet (UV-C) light should be studied in future research to improve the disinfection of strawberries.info:eu-repo/semantics/acceptedVersio
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