Problem zaleta regulatora i izvedbe funkcije za njegovo sprečavanje

Glavni zadatak ovog rada bio je prikazati i usporediti kakvoću regulacije u regulacijskim krugovima prilikom nastupanja efekta zaleta kada regulator posjeduje funkciju za sprječavanje. Problem zaleta regulatora (wind-up effect) je nepoželjan efekt u regulacijskim krugovima koji se događa kod regulatora koji imaju integralno vladanje, a u regulacijskom krugu postoji amplitudno ograničenje. Kada izvršni član uđe u ograničenje povratna veza se prividno prekida i sustav radi u otvorenoj pelji što izaziva drastično pogoršanje kakvoće regulacije. Kako bi se smanjio utjecaj takvog efekta potrebno je primjeniti metode sprječavanja efekta zaleta. U praksi se najčešće koriste tri metode: povratno integriranje, uvjetno integriranje i automatsko resetiranje. Simulacijom u Matlabu prikazana je efikasnost svake metode na dva tipa regulacijskih krugova s PT2 i IT1 procesima, koji se upravljaju s PI regulatorom.The main task of this thesis was to show and compare quality in regulation circuits during appereance of windup effect when regulator has function for it's prevention. Wind-up problem of regulator is undesirable effect in regulation circuits which is happening when regulator have integrally conduct and when there is amplitude limitation. When control signal enters the restriction feedback stops and system works in open loop which causes drastic deterioration quality of regulation. To reduce the imapct of that effect it is necessary to apply methods that are developed for that cases. The most commonly used methods in praxis are: back calculation, conditional integration and automatic reset. Simulation models that were made in Matlab shows the efficiency of every methods which are implemented on regulation circuits with PI regulator and PT2, IT1 processes and quality of regulation in graphic form and results in numeric indices

Transcriptional memory emerges from cooperative histone modifications

Background
Transcriptional regulation in cells makes use of diverse mechanisms to ensure that functional states can be maintained and adapted to variable environments; among them are chromatin-related mechanisms. While mathematical models of transcription factor networks controlling development are well established, models of transcriptional regulation by chromatin states are rather rare despite they appear to be a powerful regulatory mechanism.
Results
We here introduce a mathematical model of transcriptional regulation governed by histone modifications. This model describes binding of protein complexes to chromatin which are capable of reading and writing histone marks. Molecular interactions between these complexes and DNA or histones create a regulatory switch of transcriptional activity possessing a regulatory memory. The regulatory states of the switch depend on the activity of histone (de-) methylases, the structure of the DNA-binding regions of the complexes, and the number of histones contributing to binding. 
We apply our model to transcriptional regulation by trithorax- and polycomb- complex binding. By analyzing data on pluripotent and lineage-committed cells we verify basic model assumptions and provide evidence for a positive effect of the length of the modified regions on the stability of the induced regulatory states and thus on the transcriptional memory.
Conclusions
Our results provide new insights into epigenetic modes of transcriptional regulation. Moreover, they implicate well-founded hypotheses on cooperative histone modifications, proliferation induced epigenetic changes and higher order folding of chromatin which await experimental validation. Our approach represents a basic step towards multi-scale models of transcriptional control during development and lineage specification. 
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Optimizacija faktora opadanja u vremenski ponderiranoj (BRW) simulaciji: Posljedice za izračun VAR-a u mediteranskim zemljama

In this paper we propose an optimisation approach to determining the optimal decay factor in time weighted (BRW) simulation. Testing of BRW simulation with different decay factors and competing VaR models is performed on a sample of nine Mediterranean countries, over a four year period that includes the ongoing financial crisis. After optimisation the BRW simulation is among the best performing tested VaR models, second only to EVT approaches. Optimising the decay factor in regards to Lopez function results in decay factor estimates that are higher than usually employed 0.97 and 0.99. The optimal decay factors are stable over time and provide significantly better backtesting results than the standard assumptions.U radu se predlaže optimizacijski pristup određivanju optimalnog faktora opadanja u vremenski ponderiranoj (BRW) simulaciji. Testiranje uspješnosti BRW simulacije sa različitim faktorima opadanja u odnosu na široki raspon VaR modela provedeno je na uzorku od devet mediteranskih zemalja tijekom razdoblja od četiri godine, uključujući i razdoblje aktualne svjetske financijske krize. Rezultati testiranja pokazuju da nakon provedene optimizacije BRW simulacija je među najuspješnijim testiranim VaR modelima zaostajući jedino za modelima temeljenim na teoriji ekstremnih vrijednosti. Optimiziranje faktora opadanja u odnosu na Lopezovu funkciju rezultira faktorima opadanja koji su viši od uobičajeno korištenih vrijednosti 0.97 i 0.99. Dobiveni optimalni faktori opadanja su izrazito stabilni tijekom testiranog razdoblja te rezultiraju značajno boljim VaR prognozama

Potential Impacts On The UK Of Future Migration From Bulgaria and Romania

This report provides evidence from which the UK Government can assess the potential impacts of migration from EU2 countries following the lifting of transitional controls at the end of 2013