4,148 research outputs found
Are We Using Autoencoders in a Wrong Way?
Autoencoders are certainly among the most studied and used Deep Learning
models: the idea behind them is to train a model in order to reconstruct the
same input data. The peculiarity of these models is to compress the information
through a bottleneck, creating what is called Latent Space. Autoencoders are
generally used for dimensionality reduction, anomaly detection and feature
extraction. These models have been extensively studied and updated, given their
high simplicity and power. Examples are (i) the Denoising Autoencoder, where
the model is trained to reconstruct an image from a noisy one; (ii) Sparse
Autoencoder, where the bottleneck is created by a regularization term in the
loss function; (iii) Variational Autoencoder, where the latent space is used to
generate new consistent data. In this article, we revisited the standard
training for the undercomplete Autoencoder modifying the shape of the latent
space without using any explicit regularization term in the loss function. We
forced the model to reconstruct not the same observation in input, but another
one sampled from the same class distribution. We also explored the behaviour of
the latent space in the case of reconstruction of a random sample from the
whole dataset
Seismic response of the geologically complex alluvial valley at the "Europarco Business Park" (Rome - Italy) through instrumental records and numerical modelling
The analysis of the local seismic response in the “Europarco Business Park”, a recently urbanized district of Rome (Italy) developed over the alluvial valley of the “Fosso di Vallerano” stream, is here presented. A high-resolution geological model, reconstructed over 250 borehole log-stratigraphies, shows a complex and heterogeneous setting of both the local Plio- Pleistocene substratum and the Holocene alluvia. The local seismo-stratigraphy is derived by a calibration process performed through 1D numerical modelling, accounting for: i) 55 noise measurements, ii) 10 weak motion records obtained through a temporary velocimetric array during the August 2009 L’Aquila- Gran Sasso seismic sequence and iii) one cross-hole test available from technical report. Based on the reconstructed seismo- stratigraphy, the local seismic bedrock is placed at the top of a gravel layer that is part of the Pleistocene deposits and it does not correspond to the local geological bedrock represented by Plio-Pleistocene marine deposits. 1D amplification functions were derived via numerical modelling along three representative sections that show how in the Fosso di Vallerano area two valleys converge into a single one moving from SE toward NW. The obtained results reveal a main resonance at low frequency (about 0.8 Hz) and several higher resonance modes, related to the local geological setting. Nonlinear effects are also modelled by using strong motion inputs from the official regional dataset and pointed out a general down-shift (up to 0.5 Hz) of the principal modes of resonance as well as an amplitude reduction of the amplification function at frequencies higher than 7 Hz
Molecular typing of Staphylococcus pseudintermedius canine strains by three commonly used techniques
Staphylococcus pseudintermedius is a newly described species of Staphylococcus regarded as the main causative agent of canine pyoderma [1]. S. pseudintermedius infection was recently described in humans. An important feature of this pathogen is the high genetic identity with two other species of staphylococci, namely S. intermedius and S. delphini, which are included all together in the Staphylococcus Intermedius Group (SIG) [2]. This scenario seriously hampers phenotypic differentiation of these three pathogens. Despite this, only in 2008 was described the first molecular protocol for diagnostic identification of S. pseudintermedius [3]. The aim of this work was to investigate the presence of different biotypes of S. pseudintermedius obtained from clinically relevant cases of pyoderma in dogs using three molecular methods commonly used to type bacteria: the Ribosomal Spacers Amplification (RSA), the Random Amplification of Polymorphic DNA (RAPD) and the Restriction Fragment Length Polymorphism (RFLP). A total of 46 different strains were included in this work. The application of the RSA technique, which was applied here for the first time, identified the presence of S. pseudintermedius, although it did not allow any differentiation between biotypes. The RAPD assay showed a single cluster that assembles all the interested strains that are grouped in three different sub-clusters (Fig. 1). The RFLP technique showed the most discriminative power, providing the opportunity to clearly identify this bacterium. In conclusion, the use of these three different techniques allows to clearly identify S. pseudintermedius and to observe the presence of different biotypes. In future it could be interesting to couple these results with the determination of the antibiotic resistance in order to verify if certain Multi Drug Resistant strains have particular RSA and RAPD profiles
Automation in 3D cellular system in Live-Imaging with Microfluidic Technology CELLviewer®
Differences observed when comparing cell cultures in 2D and 3D is morphological dissimilarity and their evolution over time. Cells grown in a monolayer tend to flatten on the bottom of the plate by adhering and spreading on the horizontal plane without expanding into the vertical dimension; § Mitochondria are involved in crucial cellular tasks controlling the cell cycle and growth such as cell signaling, differentiation, and death. Damage to and subsequent dysfunction of mitochondria play a role in various diseases like diabetes, myopathy and other systemic disorders; § CELLviewer® enables the simultaneous 3D cell culture and live cell imaging as well, featuring microfluidics and time-lapse multicolour epifluorescence microscopy; § Single cell tracking in 3D space is now possible and is combined with subsequent biochemical analyses of individually tracked cells, keeping their identity traceable with CELLviewer® system; q Jurkat (ATCC) Cells grown at 37°C and 5% CO2; q Medium RPMI 1640 soil (Gibco, Life Technologies, Thermo Fisher Scientific), with 2 mM of L-glutamine, 10% FBS, 100 units/mL of penicillin and 100 mg/mL of streptomycin; q MitoGreen (PromoKine, PromoCell) incubated for 20 minutes in the dark at 37°C with MitoGreen 200 mM; q The sample is then piped inside a 50ml Falcon tube closed with a 50ml CELLviewer® DOCK and flowed inside the cartridge chamber; q CELLviewer® automatically captures sample images in Brightfield channel and GFP channel; q ImageJ software was used for image analysis using the Measure function to calculate the diameter of a single cell; q 3D surface plot plug-in to display in 3D the distribution of the intensity of spatial fluorescence; Staining of mitochondria with fluorescent dyes, antibodies or fluorescent molecules can greatly facilitate studies of their function and distribution and the viability of cells in healthy and diseased individuals. The preliminary experience conducted with CELLviewer indicates that this equipment responds to the needs of individual operators as it consists of a synthesis of different integrated tools, which works both with manual and automated control. A microfluidic system has been developed and demonstrated that the 3D model can locate the 3D model spatially, it's possible to carry out experiments in direct time in terms of physiology, toxicology and clinical pharmacology. The entire automated system allows full autonomy and protocol management thanks to the software making the operator free to conduct other work, thus increasing the productivity of his project. In summary, the proposed microfluidic technology can serve as a new platform approach, which has the potential to advance studies at the cellular level. Single-cell Jurkat cells was isolated and imaged for 4 and 7 hours respectively and intensified labelling of the mitochondria and fluidic transport were observed over time. CELLviewer® can obtain detailed images of current cellular morphology with resolution and high-quality data; employing time-lapse imaging can be achieved, the evolution of cells and their 3D morphology
Earthquake-triggered landslide susceptibility in Italy by means of Artificial Neural Network
The use of Artificial Neural Network (ANN) approaches has gained a significant role over the last decade in the field of predicting the distribution of effects triggered by natural forcing, this being particularly relevant for the development of adequate risk mitigation strategies. Among the most critical features of these approaches, there are the accurate geolocation of the available data as well as their numerosity and spatial distribution. The use of an ANN has never been tested at a national scale in Italy, especially in estimating earthquake-triggered landslides susceptibility. The CEDIT catalogue, the most up-to-date national inventory of earthquake-induced ground effects, was adopted to evaluate the efficiency of an ANN to explain the distribution of landslides over the Italian territory. An ex-post evaluation of the ANN-based susceptibility model was also performed, using a sub-dataset of historical data with lower geolocation precision. The ANN training highly performed in terms of spatial prediction, by partitioning the Italian landscape into slope units. The obtained results returned a distribution of potentially unstable slope units with maximum concentrations primarily distributed in the central Apennines and secondarily in the southern and northern Apennines. Moreover, the Alpine sector clearly appeared to be divided into two areas, a western one with relatively low susceptibility to earthquake-triggered landslides and the eastern sector with higher susceptibility. Our work clearly demonstrates that if funds for risk mitigation were allocated only on the basis of rainfall-induced landslide distribution, large areas highly susceptible to earthquake-triggered landslides would be completely ignored by mitigation plans.</p
On nonlinear model predictive direct yaw moment control for trailer sway mitigation
In car–trailer combinations, the hitch angle is the relative yaw angle
between towing car and trailer. The literature has shown that the
inclusion of the hitch angle measurement for the feedback control
of trailer oscillations can bring safety benefits, compared with conventional trailer sway mitigation algorithms based on the yaw rate of
the car. Given the nonlinearity of the vehicle system in the typical
conditions requiring the hitch angle control function intervention,
nonlinear model-based controllers could be an effective solution.
This paper presents four real-time implementable nonlinear model
predictive control (NMPC) formulations, using the hitch angle measurement for the torque-vectoring (TV) control of an electric frontwheel drive car towing a trailer. The simulation results show that:
(i) the active safety is enhanced by the proposed NMPC TV formulations, with respect to a benchmarking NMPC TV controller only based
on the control of the towing car; (ii) the NMPC formulations that
directly constrain the hitch angle error, or perform continuous hitch
angle tracking, outperform those that modify the reference yaw rate
or yaw rate error based on the hitch angle error; and (iii) the NMPC
approaches including a dynamic model of the trailer are robust with
respect to variations of trailer parameters
Разработка агрегатора данных о погоде и прогнозов погоды
Nowadays we frequently can't say which clothes weshould wear tomorrow. The problem is that there is no weather forecast service which can provide us exact weather forecast even for tomorrow, needless to say about further future. Main purpose of this work is to design system that will predict which weather forecast service should be used today to know weather for tomorrow. Authors suggest to evaluate forecasting value of temperature relying on statistics. They describe steps which they need to pass to achieve the purpose. As a result authors want to develop software which can provide weather forecast with higher probability than all existing services
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