Search results for "Biological system"
showing 10 items of 319 documents
LA MICROSCOPIA ELETTRONICA (SEM, CLSM) PER L’ANALISI DI MICROSISTEMI BIOLOGICI CHE COLONIZZANO I BENI CULTURALI
2012
RIASSUNTO - Il degrado dei materiali con cui sono realizzate le opere d’arte, è spesso causato dall’attività di macro e micro organismi (piante, insetti, licheni, alghe, batteri, attinomiceti etc.), denominati biodeteriogeni. Presenti in tutti gli habitat terrestri, costituiscono un serio problema per la conservazione sia in siti outdoor sia confinati, come biblioteche, archivi, istituti mussali, depositi e, comunque, in tutti quei luoghi dove si attua la conservazione/fruizione dei manufatti. In genere, non vi è luogo di conservazione che non mostri tracce di parziali o estese infestazioni/colonizzazioni che comportano alterazioni più o meno consistenti dei manufatti presenti. Le alterazio…
Genetic relationships between sympatric and allopatric Coregonus ciscoes in North and Central Europe
2021
Abstract Background Sympatric speciation along ecological gradients has been studied repeatedly, in particular in freshwater fishes. Rapid post-glacial ecological divergence has resulted in numerous endemic species or ecologically distinct populations in lakes of the temperate zones. Here, we focus on the Baltic cisco (Coregonus albula) complex, to study the genetic similarity among two pairs of sympatric autumn- and spring-spawning populations from post-glacial German Lakes Stechlin and Breiter Luzin. For comparison, we included a similar pair of sympatric populations from the Swedish Lake Fegen. We wanted to explore potential genetic similarities between the three sympatric cisco populati…
COVARIANCE AND CORRELATION ESTIMATORS IN BIPARTITE SYSTEMS
2017
We present a weighted estimator of the covariance and correlation in bipartite complex systems with a double layer of heterogeneity. The advantage provided by the weighted estimators lies in the fact that the unweighted sample covariance and correlation can be shown to possess a bias. Indeed, such a bias affects real bipartite systems, and, for example, we report its effects on two empirical systems, one social and the other biological. On the contrary, our newly proposed weighted estimators remove the bias and are better suited to describe such systems.
Modified locally weighted—Partial least squares regression improving clinical predictions from infrared spectra of human serum samples
2012
Locally weighted partial least squares regression (LW-PLSR) has been applied to the determination of four clinical parameters in human serum samples (total protein, triglyceride, glucose and urea contents) by Fourier transform infrared (FTIR) spectroscopy. Classical LW-PLSR models were constructed using different spectral regions. For the selection of parameters by LW-PLSR modeling, a multi-parametric study was carried out employing the minimum root-mean square error of cross validation (RMSCV) as objective function. In order to overcome the effect of strong matrix interferences on the predictive accuracy of LW-PLSR models, this work focuses on sample selection. Accordingly, a novel strateg…
A multicompartment model for open-loop control of glucose in insulin-dependent diabetics
1990
This paper describes a model that has been developed for individually adjusted therapy management in insulin-dependent diabetics. The multicompartment model considers all relevant aspects of glucose kinetics and its dependence on insulin. The structure of the model reflects that of the physiological system. Its parameters can be classified into (a) general parameters that are independent of the individual, (b) classifying parameters that are related systematically to the individual, and (c) distinguishing parameters. Classifying parameters allow a very convenient adjustment to relevant features of the individual like sex, age, body weight and length. The model can be employed in open-loop c…
Measuring High-Order Interactions in Rhythmic Processes Through Multivariate Spectral Information Decomposition
2021
Many complex systems in physics, biology and engineering are modeled as dynamical networks and described using multivariate time series analysis. Recent developments have shown that the emergent dynamics of a network system are significantly affected by interactions involving multiple network nodes which cannot be described using pairwise links. While these higher-order interactions can be probed using information-theoretic measures, a rigorous framework to describe them in the frequency domain is still lacking. This work presents an approach for the spectral decomposition of multivariate information measures, capable of identifying higher-order synergistic and redundant interactions betwee…
A novel prototype to closely mimic mastication for in vitro dynamic measurements of flavour release
2005
International audience; Flavour release during eating of a food depends upon many parameters that can hardly be managed. In-vivo measurements by the APCI MS-nose method allowed temporal sensory evaluation and flavour release data to be directly correlated, but several limitations have frequently been reported. These were: high inter-individual variability, low repeatability of measurements, and weak experiment throughput due to panellists' exhaustion. To overcome most of these limitations, the use of an artificial mouth for online mesurement of flavour release is recommended. However, the systems used in previous reports were limited in terms of reproducing in-vivo oral functions and parame…
Kinetic modelling of passive transport and active efflux of a fluoroquinolone across Caco-2 cells using a compartmental approach in NONMEM.
2005
The purpose was to develop a general mathematical model for estimating passive permeability and efflux transport parameters from in vitro cell culture experiments. The procedure is applicable for linear and non-linear transport of drug with time,10 or10% of drug transport, negligible or relevant back flow, and would allow the adequate correction in the case of relevant mass balance problems. A compartmental kinetic approach was used and the transport barriers were described quantitatively in terms of apical and basolateral clearances. The method can be applied when sink conditions are not achieved and it allows the evaluation of the location of the transporter and its binding site. In this …
Analysis of neuronal networks in the visual system of the cat using statistical signals--simple and complex cells. Part II.
1978
Superimposing additively a two-dimensional noise process to deterministic input signals (bars) the neurons of area 17 show a class-specific reaction for the task of signal extraction. Moving both parts of the signals simultaneously and varying the signal to noise ratio (S/N) the simple cells achieve the same performance as resulted from the psychophysical experiment. Type I complex cells extract moving deterministic signals (i.e. bars) from the stationary noise, whereas in the answers of Type II complex cells the statistical parts of the signals predominate. Considering the different cell types each as a series of a linear and a nonlinear system one obtains the cell specific space-time freq…
Adversarial reverse mapping of condensed-phase molecular structures: Chemical transferability
2021
Switching between different levels of resolution is essential for multiscale modeling, but restoring details at higher resolution remains challenging. In our previous study we have introduced deepBackmap: a deep neural-network-based approach to reverse-map equilibrated molecular structures for condensed-phase systems. Our method combines data-driven and physics-based aspects, leading to high-quality reconstructed structures. In this work, we expand the scope of our model and examine its chemical transferability. To this end, we train deepBackmap solely on homogeneous molecular liquids of small molecules, and apply it to a more challenging polymer melt. We augment the generator's objective w…