From dependency to causality: a machine learning approach

The relationship between statistical dependency and causality lies at the heart of all statistical approaches to causal inference. Recent results in the ChaLearn cause-effect pair challenge have shown that causal directionality can be inferred with good accuracy also in Markov indistinguishable configurations thanks to data driven approaches. This paper proposes a supervised machine learning approach to infer the existence of a directed causal link between two variables in multivariate settings with $n>2$ variables. The approach relies on the asymmetry of some conditional (in)dependence relations between the members of the Markov blankets of two variables causally connected. Our results show that supervised learning methods may be successfully used to extract causal information on the basis of asymmetric statistical descriptors also for $n>2$ variate distributions.Comment: submitted to JML

Herstellung von β-Tricalciumphosphat Gerüsten durch Gefrierstrukturierung sowie Aufklärung und Evaluation der Methode

Die vorliegende Arbeit soll zur Aufklärung und Weiterentwicklung des Verständnisses der grundlegenden Mechanismen der Gefrierstrukturierung beitragen und am Beispiel von β-TCP das Potential und die Grenzen der Methode aufzeigen. Die erfolgreiche Anwendung der Gefrierstrukturierungsmethode auf β-TCP führt zu Gerüsten mit durchgängigen und gerichteten lamellaren Poren. Dabei lässt sich die Porosität zwischen 47 bis 87 % durch den Feststoffgehalt der Suspension von 10 bis 30 Vol-% einstellen. Die Geschwindigkeit der gerichteten Suspensionserstarrung zwischen 10 und 30 µm/s legt die Keramiklamellenbreite von 4,5 bis 22 µm und die Porenbreite von 8 bis 40 µm fest. Durch die gezielte Festsetzung der Gerüststruktur lassen sich die mechanischen Eigenschaften variieren und Gerüste mit Druckfestigkeiten von 0,3 bis 53 MPa erzeugen. Mit steigender Erstarrungsgeschwindigkeit lassen sich bei konstanter Porosität die Druckfestigkeiten der Gerüste durch Änderungen der Struktur und Strukturgrößen erhöhen. Hierfür wird ein qualitatives Erklärungsmodell auf Grundlage der Bruch- und Strukturmechanik abgeleitet. Eine konstante Erstarrungsfrontgeschwindigkeit wird durch die Anwendung eines Erstarrungsfunktionsansatzes auf Basis einer analytischen Lösung der Wärmeleitungsgleichung umgesetzt. Dies ist der Schlüssel für die Erzeugung konstanter Strukturgrößen innerhalb der Gerüste. Die Gültigkeit der Funktion und Strukturbildung wird experimentell nachgewiesen. Die Abhängigkeit der Strukturgröße von der Erstarrungsgeschwindigkeit und den physikalischen Eingangsgrößen der Suspension lässt sich durch eine Erstarrungstheorie beschreiben und berechnen. Eine Imprägnation der Gerüste mit dem resorbierbaren Polymer PCL führt zu Kompositgerüsten mit gesteigerter Schadenstoleranz und Festigkeit. Ein mikrostrukturelles Modell beschreibt dieses mit der Bildung von verstreckten PCL Mikrofibrillen und deren Einfluss auf eine Reduzierung kritischer Rissspitzenspannungen

Genetic diversity and population viability of endemic Telestes species (Cyprinidae, Actinopterygii)

Endemske vrste roda Telestes ubrajaju se među najugroženije vrste slatkovodnih riba u Europi, a u Hrvatskoj ih živi čak osam. Zbog opterećenosti slatkovodnih ekosustava, degradacija staništa, melioracija, regulacija vodotoka i unošenja invazivnih svojti, vrste roda Telestes smatraju se kritično ugrožene prema kategorijama i kriterijima IUCN-a. Kako bih predložila prikladne mjere zaštite te proširila znanje o biologiji, ekologiji i genetici tih vrsta, izračunala sam mjere varijacija slijedova DNA unutar i između populacija, procijenila povezanost populacija, njihovu efektivnu veličinu i provela ih kroz različite scenarije potencijalnih katastrofa radi ispitivanja njihove vijabilnosti. Migracije populacija iste vrste koje obitavaju na više lokaliteta nisu recipročne i uvijek više jedinki migrira u jednom smjeru – nizvodno, uzvodno i podzemno. S obzirom na to da su efektivne veličine svih istraživanih vrsta relativno male, osjetljivije su na promjene u okolišu. Najosjetljivija vrsta je T. karsticus, a najotpornije su T. turskyi i T. fontinalis.The endemic Telestes species are among the most endangered freshwater fish in Europe, in Croatia lives eight of them. Due to the burden of freshwater ecosystems, habitat degradation, melioration, water regulation and invasive species, Telestes is classified into the critically endangered IUCN Red List category. To propose adequate protection measures and expand knowledge of biology, ecology and genetics of these species, I calculated the variations of DNA sequences among populations, estimated the population correlation and their effective size, and carried the species through different scenarios of potential disasters to test their viability. Populations migrates are not reciprocal, more and more migrants migrate in one direction - downstream, upstream and underground. Since the effective sizes of all the investigated species are relatively small, they are more sensitive to changes in the environment. The most vulnerable species is T. karsticus, and the most resistant are T. turskyi and T. fontinalis

Genetic diversity and population viability of endemic Telestes species (Cyprinidae, Actinopterygii)

Endemske vrste roda Telestes ubrajaju se među najugroženije vrste slatkovodnih riba u Europi, a u Hrvatskoj ih živi čak osam. Zbog opterećenosti slatkovodnih ekosustava, degradacija staništa, melioracija, regulacija vodotoka i unošenja invazivnih svojti, vrste roda Telestes smatraju se kritično ugrožene prema kategorijama i kriterijima IUCN-a. Kako bih predložila prikladne mjere zaštite te proširila znanje o biologiji, ekologiji i genetici tih vrsta, izračunala sam mjere varijacija slijedova DNA unutar i između populacija, procijenila povezanost populacija, njihovu efektivnu veličinu i provela ih kroz različite scenarije potencijalnih katastrofa radi ispitivanja njihove vijabilnosti. Migracije populacija iste vrste koje obitavaju na više lokaliteta nisu recipročne i uvijek više jedinki migrira u jednom smjeru – nizvodno, uzvodno i podzemno. S obzirom na to da su efektivne veličine svih istraživanih vrsta relativno male, osjetljivije su na promjene u okolišu. Najosjetljivija vrsta je T. karsticus, a najotpornije su T. turskyi i T. fontinalis.The endemic Telestes species are among the most endangered freshwater fish in Europe, in Croatia lives eight of them. Due to the burden of freshwater ecosystems, habitat degradation, melioration, water regulation and invasive species, Telestes is classified into the critically endangered IUCN Red List category. To propose adequate protection measures and expand knowledge of biology, ecology and genetics of these species, I calculated the variations of DNA sequences among populations, estimated the population correlation and their effective size, and carried the species through different scenarios of potential disasters to test their viability. Populations migrates are not reciprocal, more and more migrants migrate in one direction - downstream, upstream and underground. Since the effective sizes of all the investigated species are relatively small, they are more sensitive to changes in the environment. The most vulnerable species is T. karsticus, and the most resistant are T. turskyi and T. fontinalis

Genetic diversity and population viability of endemic Telestes species (Cyprinidae, Actinopterygii)

Endemske vrste roda Telestes ubrajaju se među najugroženije vrste slatkovodnih riba u Europi, a u Hrvatskoj ih živi čak osam. Zbog opterećenosti slatkovodnih ekosustava, degradacija staništa, melioracija, regulacija vodotoka i unošenja invazivnih svojti, vrste roda Telestes smatraju se kritično ugrožene prema kategorijama i kriterijima IUCN-a. Kako bih predložila prikladne mjere zaštite te proširila znanje o biologiji, ekologiji i genetici tih vrsta, izračunala sam mjere varijacija slijedova DNA unutar i između populacija, procijenila povezanost populacija, njihovu efektivnu veličinu i provela ih kroz različite scenarije potencijalnih katastrofa radi ispitivanja njihove vijabilnosti. Migracije populacija iste vrste koje obitavaju na više lokaliteta nisu recipročne i uvijek više jedinki migrira u jednom smjeru – nizvodno, uzvodno i podzemno. S obzirom na to da su efektivne veličine svih istraživanih vrsta relativno male, osjetljivije su na promjene u okolišu. Najosjetljivija vrsta je T. karsticus, a najotpornije su T. turskyi i T. fontinalis.The endemic Telestes species are among the most endangered freshwater fish in Europe, in Croatia lives eight of them. Due to the burden of freshwater ecosystems, habitat degradation, melioration, water regulation and invasive species, Telestes is classified into the critically endangered IUCN Red List category. To propose adequate protection measures and expand knowledge of biology, ecology and genetics of these species, I calculated the variations of DNA sequences among populations, estimated the population correlation and their effective size, and carried the species through different scenarios of potential disasters to test their viability. Populations migrates are not reciprocal, more and more migrants migrate in one direction - downstream, upstream and underground. Since the effective sizes of all the investigated species are relatively small, they are more sensitive to changes in the environment. The most vulnerable species is T. karsticus, and the most resistant are T. turskyi and T. fontinalis

Using decision trees to evaluate courier companies from the perspective of online retailers

The analysis of the research problem started from listing the issues of decision theory and the decision-making process that support the process of building decision trees. The area in question covers a procedure for building and proceeding when creating decision trees. The solution to the research problem consists in defining decision variables and arranging them into logical statements by writing down all possible variants and only accounting for the true ones. True solutions derived from coding were detailed and the number of occurring decision trees was calculated in the case under consideration. The decision problem was presented in the form of decision trees, which made it possible to select the optimum decision tree. The obtained results were considered and the optimum decision tree was chosen. At the same time, the record of decision variables was analyzed, providing the answer as to which courier company will best meet expectations of entrepreneurs and ensure the most satisfying cooperation. That company turned out to be K-EX. The article aimed to select a courier company from the perspective of online retailers, with the selection having been made using the method of decision trees based on four basic criteria defined within the research

Early and Preschool Education of Gifted Children

U radu se obrađuju tematika i problematika darovite djece u sustavu ranoga i predškolskog odgoja i obrazovanja kako bi se pomoglo aktualiziranju teme koja, nezasluženo, tek povremeno ispliva na površinu fokusa javnosti kada stručnjaci iz tog područja ukazuju na nedostatke i poteškoće u tom području. Stoga ovaj rad, osim o općenitim pojmovima vezanim za darovitosti, govori i o zakonodavnom okviru koji obuhvaća niz zakonskih odredbi koje definiraju darovitost te reguliraju načine rada s darovitom djecom. Kako bi se višegodišnja praksa neprepoznavanja i neprimjerenog odnosa prema darovitoj djeci u ranom i predškolskom odgoju i obrazovanju promijenila i poboljšala, u radu se ističe potreba efikasnijeg provođenja zakonskih odredbi i potreba povećanja broja educiranih odgojitelja koji imaju ključnu ulogu u identifikaciji darovite djece. Nadalje, ukazuje se na posljedice izostanka identifikacije i nepružanja odgovarajuće potpore darovitoj djeci te načinima rada s darovitom djecom. U radu je korištena literatura stručnjaka iz područja odgoja i obrazovanja te brojni zakoni koji u svom sadržaju obuhvaćaju tematiku darovite djece

Dermokozmetički pripravci s UV zaštitom i zdravlje kože

Cilj istraživanja Cilj predloženog specijalističkog rada je prikazati informacije korisne za razumijevanje utjecaja UV zračenja na kožu, analizirati najčešće korištene UV filtre te odgovoriti na aktualna pitanja o sigurnosti njihova korištenja. Rad doprinosi osvješćivanju važnosti pravilnog korištenja pripravka s UV zaštitom, upoznavanju s različitim UV filtrima te upozorava na štetnost prekomjernog izlaganja Sunčevom zračenju. Materijal i metode U izradi teorijskog specijalističkog rada korišteni su različiti preglednici znanstvene literature, znanstvene i stručne knjige te mrežne stranice sa srodnom tematikom. Specijalistički rad temeljen je na radovima objavljenima u znanstvenim časopisima i stručnim knjigama. Metode rada bile su uglavnom pretraživanje pomoću ključnih riječi vezanih za određeno potpoglavlje specijalističkog rada. Rezultati UV filtri u pripravcima za zaštitu kože od Sunčevog zračenja, mogu biti fizički i kemijski. Fizički filtri se ne upijaju u kožu, nego odbijaju ultraljubičasto zračenje pa se preporučuju u pripravcima za djecu. Kemijski filtri selektivno apsorbiraju ultraljubičaste zrake. Pojedini dermokozmetički pripravci sadrže i kemijske filtre skupa s fizičkim te sinergijski pružaju širokospektralnu zaštitu. O sigurnosti korištenja pripravaka za zaštitu od Sunčevog zračenja nema toliko informacija koliko ima o štetnom djelovanju UV zračenja na zdravlje kože. Pojedini UV filtri (PABA, benzofenon, cimetna kiselina...) u malobrojnim su slučajevima izazvali iritaciju kože te su potrebna daljnja istraživanja o mehanizmima njihova djelovanja. Zaključak Štetnost topikalne primjene dermokozmetičkih pripravaka za zaštitu od UV zračenja nije dokazana, ali njihov negativni utjecaj na zdravlje kože dobro je poznat. Najsigurnije je korištenje širokospektralne zaštite, učestalo obnavljanje i obilno nanošenje pripravka na kožu te izbjegavanje Sunca dok je intenzitet zračenja najveći.Objective The aim of this study is to present information useful for understanding the effect of UV radiation on the skin, using UV filters and answering current safety questions why they are used. The study contributes to the awareness of the importance of using UV protection properly, getting acquainted with the various UV filters and warning about the harmful effects of overexposure to sunlight. Material And Methods The research method is based on literature research according to described topic of this study. Various scientific literature browsers such as databases (PloS One), the Research Gate social network, scientific books, and related sites have been used for this study. The methods of study were mainly research using keywords related to a specific subchapter. Results UV filters contained in sunscreen preparations are divided into physical and chemical filters. Physical filters not absorbed into the skin, they reflect ultraviolet radiation. Chemical filters selectively absorb ultraviolet rays. Some dermocosmetic preparations also contain chemical filters in combination with physical ones and synergistically provide broad spectrum protection. Commercially physical and chemical sunscreen preparations have a low incidence of adverse effects. In rare cases certain UV filters (PABA, benzophenone, cinnamic acid ...) have caused skin irritation. Conclusion Sun radiation has a negative impact on skin health. The toxicity of UV filters in sunscreen preparations has not been proven, and the benefits they provide in skin protection outweigh any potential risks of application

Early and Preschool Education of Gifted Children

U radu se obrađuju tematika i problematika darovite djece u sustavu ranoga i predškolskog odgoja i obrazovanja kako bi se pomoglo aktualiziranju teme koja, nezasluženo, tek povremeno ispliva na površinu fokusa javnosti kada stručnjaci iz tog područja ukazuju na nedostatke i poteškoće u tom području. Stoga ovaj rad, osim o općenitim pojmovima vezanim za darovitosti, govori i o zakonodavnom okviru koji obuhvaća niz zakonskih odredbi koje definiraju darovitost te reguliraju načine rada s darovitom djecom. Kako bi se višegodišnja praksa neprepoznavanja i neprimjerenog odnosa prema darovitoj djeci u ranom i predškolskom odgoju i obrazovanju promijenila i poboljšala, u radu se ističe potreba efikasnijeg provođenja zakonskih odredbi i potreba povećanja broja educiranih odgojitelja koji imaju ključnu ulogu u identifikaciji darovite djece. Nadalje, ukazuje se na posljedice izostanka identifikacije i nepružanja odgovarajuće potpore darovitoj djeci te načinima rada s darovitom djecom. U radu je korištena literatura stručnjaka iz područja odgoja i obrazovanja te brojni zakoni koji u svom sadržaju obuhvaćaju tematiku darovite djece

La [delta]-azaproline: impact conformationnel de son incorporatrion dans des pseudopeptides

This work describes the incoporation the [delta]-azaproline in pseudopeptides for conformational analysis and biological applications. The first chapter of this thesis is devoted to the development of a new substrate of the type Suc Ala X [delta]azaPro Phe [rho] NA (where X is an amino acid) able to measure the catalytic activity of PPIases. These enzymes have shown great interests in the prevention of transplant rejection and in the treatment of Alzheimer's disease because they can interconvert the cis and trans isomers of X-Pro peptidic bond. The second section describes the incorporation of the [delta]-azaproline into pseudotripeptides in which the reactivity of both nitrogen atoms of this surrogate was investigated. It could be demonstrated in particular that the supplementary nitrogen atom of azaproline is much more reactive than the native one because of the steric hindrance generated by the Boc protecting group and the spontaneous oxidation of the CH[alpha] NH[delta] bond represent a huge problem in the peptidic coupling.Finally, the last part of this thesis is dedicated to the conformational analysis of pseudotripeptides. These analyzes are designed to determine the influence of a supplementary nitrogen atom, in [delta] position into proline’s cycle, which can be free or protected by a cluttered group on the conformation of the X-[psy]Pro bond. Spectroscopic techniques such as NMR and IR enabled to demonstrate that steric hindrance generated by a Boc group on [delta] position with the side chain of amino acid upstream this surrogate promotes cis conformation by formation of a ten-membered ringCe travail décrit l’incorporation de la [delta]-azaproline dans des pseudopeptides en vue d’analyses conformationnelles et applications biologiques. Le premier chapitre de ce manuscrit est consacré à l’élaboration d’un nouveau substrat de type Suc Ala-X-[delta]azaPro-Phe-[rho]-NA (où X est un acide aminé) capable de mesurer l’activité catalytique des PPIases. Ces enzymes ont déjà montré un grand intérêt dans la prévention des rejets de greffes et dans le traitement de la maladie d’Alzheimer car elles sont capables d’isomériser le lien X-Pro de la conformation cis vers la conformation trans. Le second chapitre décrit l’incorporation de la [delta]-azaproline dans des pseudotripeptides et l’étude de la réactivité des deux atomes d’azote de cet analogue. Il a pu notamment être mis en évidence que l’atome d’azote supplémentaire de la [delta] azaproline est beaucoup plus réactif que l’atome d’azote natif car l’encombrement stérique généré par le groupement Boc et l’oxydation spontanée de la liaison CH[alpha] NH[delta] représente un frein au bon déroulement du couplage peptidique. Finalement, la dernière partie de ce manuscrit est consacrée à l’analyse conformationnelle des pseudotripeptides synthétisés. Ces analyses ont pour but de déterminer l’influence d’un atome d’azote supplémentaire, en position [delta] du cycle de la proline, libre ou protégé par un groupement encombré sur la conformation du lien X-[psy]Pro. Les techniques spectroscopiques comme la RMN et l’IR ont permis de mettre en évidence que l’encombrement stérique généré par un groupement Boc en position [delta] avec la chaîne latérale de l’acide aminé en amont de cet analogue favorise la conformation cis par formation d’un pseudocycle en C1