Active alignment for two-beam interferometers

An active control system is described for the automatic alignment of the mirrors in a two-beam interferometer. From an initial unaligned position the active control system determines the degree of misalignment and adjusts the relative mirror positions accordingly. An embodiment of the system is described for a Michelson interferometer in which one of the mirrors is mounted upon three piezoelectric transducers PZT arranged so that they can both tilt and retard the mirror. Laser sources and corresponding photodetectors are also incorporated such that a control system can use the PZT actuators to produce a series of mirror movements relative to the fixed mirror and give a set of two-dimensional diffraction patterns one for each of the laser photodetectors. Amplitude and phase information is extracted from these patterns which enables the control system to align the mirrors such that the diffraction pattern maxima is at the center of the instrument central photodetector. In a further stage of the control algorithm, the alignment accuracy is refined using information from the laser photodetectors during retardation of the mirror. In this manner, the initial mirror alignment, maintaining that alignment during retardation and diagnosis of possible misalignment, become part of a single active control technology for instrument alignment

Complex networks and simulation strategies: An application to olive fruit fly dispersion

In this work a study for the role of different environmental factors to the evolution of olive fruit fly, via an appropriate network of population traps is given. More explicitly, the olive fruit fly is a parasitic insect that infests olive groves in many countries. Through the use of a network of traps a simulation model was developed and used to simulate the dispersion of olive fruit fly inside a real olive grove for different environmental factors, such as different starting areas of olive fruit fly presence, different temperature sets as well as different drifting distances. Results showed that the level of infestation of the grove was not dependent on the limited areas the olive fruit fly emerged but on the drifting distance a fly could travel per day

Optimal metabolic pathway activation

This paper deals with temporal enzyme distribution in the activation of biochemical pathways. Pathway activation arises when production of a certain biomolecule is required due to changing environmental conditions. Under the premise that biological systems have been optimized through evolutionary processes, a biologically meaningful optimal control problem is posed. In this setup, the enzyme concentrations are assumed to be time dependent and constrained by a limited overall enzyme production capacity, while the optimization criterion accounts for both time and resource usage. Using geometric arguments we establish the bang-bang nature of the solution and reveal that each reaction must be sequentially activated in the same order as they appear in the pathway. The results hold for a broad range of enzyme dynamics which includes, but is not limited to, Mass Action, Michaelis-Menten and Hill Equation kinetics.Comment: 14 pages, 3 figures. Paper to be presented at the 17th IFAC World Congress, Seoul, Korea, July 200

Control structure and limitations of biochemical networks

Biochemical networks typically exhibit intricate topologies that hinder their analysis with control-theoretic tools. In this work we present a systematic methodology for the identification of the control structure of a reaction network. The method is based on a bandwidth reduction technique applied to the incidence matrix of the network’s graph. In addition, in the case of mass-action and stable networks we show that it is possible to identify linear algebraic dependencies between the time-domain integrals of some species’ concentrations. We consider the extrinsic apoptosis pathway and an activation– inhibition mechanism to illustrate the application of our result

How neurons migrate: a dynamic in-silico model of neuronal migration in the developing cortex

<p>Abstract</p> <p>Background</p> <p>Neuronal migration, the process by which neurons migrate from their place of origin to their final position in the brain, is a central process for normal brain development and function. Advances in experimental techniques have revealed much about many of the molecular components involved in this process. Notwithstanding these advances, how the molecular machinery works together to govern the migration process has yet to be fully understood. Here we present a computational model of neuronal migration, in which four key molecular entities, Lis1, DCX, Reelin and GABA, form a molecular program that mediates the migration process.</p> <p>Results</p> <p>The model simulated the dynamic migration process, consistent with in-vivo observations of morphological, cellular and population-level phenomena. Specifically, the model reproduced migration phases, cellular dynamics and population distributions that concur with experimental observations in normal neuronal development. We tested the model under reduced activity of Lis1 and DCX and found an aberrant development similar to observations in Lis1 and DCX silencing expression experiments. Analysis of the model gave rise to unforeseen insights that could guide future experimental study. Specifically: (1) the model revealed the possibility that under conditions of Lis1 reduced expression, neurons experience an oscillatory neuron-glial association prior to the multipolar stage; and (2) we hypothesized that observed morphology variations in rats and mice may be explained by a single difference in the way that Lis1 and DCX stimulate bipolar motility. From this we make the following predictions: (1) under reduced Lis1 and enhanced DCX expression, we predict a reduced bipolar migration in rats, and (2) under enhanced DCX expression in mice we predict a normal or a higher bipolar migration.</p> <p>Conclusions</p> <p>We present here a system-wide computational model of neuronal migration that integrates theory and data within a precise, testable framework. Our model accounts for a range of observable behaviors and affords a computational framework to study aspects of neuronal migration as a complex process that is driven by a relatively simple molecular program. Analysis of the model generated new hypotheses and yet unobserved phenomena that may guide future experimental studies. This paper thus reports a first step toward a comprehensive in-silico model of neuronal migration.</p

ALISSA: an automated live-cell imaging system for signal transduction analyses

Probe photobleaching and a specimen’s sensitivity to phototoxicity severely limit the number of possible excitation cycles in time-lapse fluorescent microscopy experiments. Consequently, when a study of cellular processes requires measurements over hours or days, temporal resolution is limited, and spontaneous or rapid events may be missed, thus limiting conclusions about transduction events. We have developed ALISSA, a design framework and reference implementation for an automated live-cell imaging system for signal transduction analysis. It allows an adaptation of image modalities and laser resources tailored to the biological process, and thereby extends temporal resolution from minutes to seconds. The system employs online image analysis to detect cellular events that are then used to exercise microscope control. It consists of a reusable image analysis software for cell segmentation, tracking, and time series extraction, and a measurement-specific process control software that can be easily adapted to various biological settings. We have applied the ALISSA framework to the analysis of apoptosis as a demonstration case for slow onset and rapid execution signaling. The demonstration provides a clear proof-of-concept for ALISSA, and offers guidelines for its application in a broad spectrum of signal transduction studies

Καταγραφή των χαρακτηριστικών εκτέλεσης του κόρνερ της FC Barcelona και της Atl. Madrid στο πρωτάθλημα La Liga Santander την σεζόν 2018-2019.

Στην παρούσα έρευνα αναλύθηκαν, καταγράφηκαν και συγκρίθηκαν τα γωνιαία λακτίσματα (κόρνερ) της πρωταθλήτριας ομάδας FC. Barcelona και της δευτεραθλήτριας Atl. Madrid, στο ισπανικό πρωτάθλημα La Liga Santander την σεζόν 2018-2019,με απώτερο σκοπό οι προπονητές να εξάγουν χρήσιμα συμπεράσματα για την βελτίωση της επιθετικής και αμυντικής τακτικής κατά την εκτέλεση των κόρνερ. Μέσω των προγραμμάτων βίντεο-ανάλυσης WyScout και KMPlayer και ενός ειδικά διαμορφωμένου πρωτόκολλου Excel, αναλύθηκαν συνολικά 419 σε 76 αγώνες των δυο ομάδων. Ορισμένες από τις μεταβλητές που αναλύθηκαν ήταν, η χρονική εκτέλεση των κόρνερ, ο τρόπος άμυνας στην εστία, η ζώνη στην οποία πραγματοποιήθηκε τελική ενέργεια, η ύπαρξη τελικής ενέργειας και το τελικό αποτέλεσμα του αγώνα. Σύμφωνα με τα αποτελέσματα τα περισσότερα κόρνερ εκτελέστηκαν όταν το τελικό αποτέλεσμα του αγώνα ήταν η νίκη και για τις δυο ομάδες (61.39%). Όσον αφορά την χρονική στιγμή εκτέλεσης η έρευνα έδειξε ότι η πλειοψηφία των κόρνερ έγινε στα τελευταία 15 λεπτά του αγώνα (21,24%). Ως τρόπο άμυνας εντός εστίας προτιμήθηκε χωρίς ελεύθερο παίκτη σε κανένα από τα δυο δοκάρια (98,09%). Τέλος, στα περισσότερα κόρνερ δεν πραγματοποιήθηκε τελική ενέργεια (75,58%), ωστόσο στο 25% των κόρνερ υπήρξε τελική ενέργεια, εκ των οποίων το μεγαλύτερο ποσοστό (50%) και για τις δύο ομάδες έγινε από την περιοχή του πέναλτι. Εν κατακλείδι, όπως γίνεται αντιληπτό, τα γωνιαία λακτίσματα μπορούν να αποτελέσουν καθοριστικό παράγοντα στην εξέλιξη και τελική έκβαση του αγώνα. Για τον λόγο αυτό οι προπονητές πρέπει να δίνουν την απαραίτητη προσοχή και χρόνο, στην κατάλληλη προετοιμασία των ομάδων τόσο για την αντιμετώπιση όσο και για την εκμετάλλευση των κόρνερ.In the present paper, the corner kicks of the champion team FC Barcelona were analyzed, recorded and compared. to Atl. Madrid, in the Spanish Championship La Liga Santander for 2018-2019 season, with ultimate goal for coaches to draw useful conclusions to improve offensive and defensive tactics in the corner kicks. Through WyScout and KM Player, video analysis software and a specially designed Excel protocol, a total of 419 were analyzed in 76 matches between the two teams. Some of the variables analyzed were the timing of the corner kicks, the way the defense was fired, the zone in which the final action took place, the existence of the final action and the final outcome of the match. According to the results most corner kicks were executed when the final result of the match was the win for both teams (61.39%). In terms of execution time, the investigation showed that the majority of corner kicks were in the last 15 minutes of the match (21.24%). As a way of defense inside the penalty area it was preferred without a free player in either of the two goalposts (98.09%). Finally, in most corner kicks no final action was taken (75.58%), however in 25% of the corner kicks there was a final action, of which 50% for both teams was from the penalty area. In conclusion, as can be seen, corner kicks can be a determining factor in the development and outcome of the match. For this reason, coaches need to devote the necessary time and attention to properly preparing teams for both dealing and exploiting corner kicks

Maternal Obesity Induced by Diet in Rats Permanently Influences Central Processes Regulating Food Intake in Offspring

Hypothalamic systems which regulate appetite may be permanently modified during early development. We have previously reported hyperphagia and increased adiposity in the adult offspring of rodents fed an obesogenic diet prior to and throughout pregnancy and lactation. We now report that offspring of obese (OffOb) rats display an amplified and prolonged neonatal leptin surge, which is accompanied by elevated leptin mRNA expression in their abdominal white adipose tissue. At postnatal Day 30, before the onset of hyperphagia in these animals, serum leptin is normal, but leptin-induced appetite suppression and phosphorylation of STAT3 in the arcuate nucleus (ARC) are attenuated; the level of AgRP-immunoreactivity in the hypothalamic paraventricular nucleus (PVH), which derives from neurones in the ARC and is developmentally dependent on leptin, is also diminished. We hypothesise that prolonged release of abnormally high levels of leptin by neonatal OffOb rats leads to leptin resistance and permanently affects hypothalamic functions involving the ARC and PVH. Such effects may underlie the developmental programming of hyperphagia and obesity in these rats

Control structure and limitations of biochemical networks

Abstract-Biochemical networks typically exhibit intricate topologies that hinder their analysis with control-theoretic tools. In this work we present a systematic methodology for the identification of the control structure of a reaction network. The method is based on a bandwidth reduction technique applied to the incidence matrix of the network&apos;s graph. In addition, in the case of mass-action and stable networks we show that it is possible to identify linear algebraic dependencies between the time-domain integrals of some species&apos; concentrations. We consider the extrinsic apoptosis pathway and an activationinhibition mechanism to illustrate the application of our results