On the Hardness of Entropy Minimization and Related Problems

We investigate certain optimization problems for Shannon information measures, namely, minimization of joint and conditional entropies $H(X,Y)$, $H(X|Y)$, $H(Y|X)$, and maximization of mutual information $I(X;Y)$, over convex regions. When restricted to the so-called transportation polytopes (sets of distributions with fixed marginals), very simple proofs of NP-hardness are obtained for these problems because in that case they are all equivalent, and their connection to the well-known \textsc{Subset sum} and \textsc{Partition} problems is revealed. The computational intractability of the more general problems over arbitrary polytopes is then a simple consequence. Further, a simple class of polytopes is shown over which the above problems are not equivalent and their complexity differs sharply, namely, minimization of $H(X,Y)$ and $H(Y|X)$ is trivial, while minimization of $H(X|Y)$ and maximization of $I(X;Y)$ are strongly NP-hard problems. Finally, two new (pseudo)metrics on the space of discrete probability distributions are introduced, based on the so-called variation of information quantity, and NP-hardness of their computation is shown.Comment: IEEE Information Theory Workshop (ITW) 201

Adsorption of Organic Acids on Metal Oxides. The Umbrella Effect

Simultaneous interpretation of electrokinetic and adsorption data for organic ions at metal oxide surfaces is introduced. It is shown that, for the salicylic acid / hematite system, the singly charged salicylate ions react with surface –OH, groups releasing one water molecule. The salicylate ions, when bound to the surface, exhibit a pronounced »Umbrella effect«, i.e. each relatively large organic ion covers about four to six surface –OH, excluding them from the further adsorption process. Within the electrical interfacial layer, the salicylate ions are located in the plane near the onset of the diffuse layer. It is demonstrated that the interpretation of adsorption data solely may lead to erroneous conclusions regarding the mechanism of binding and the structure of the interfacial layer. Electrokinetic measurements provide useful information, enabling the solution of the above problem

Symbolic interactionism, mass panics and urban legends

Konstrukcionistički pristup društvenim problemima razvio je tezu o masovnim panikama i urbanim legendama kao 'nekonstruisanim društvenim problemima'. Ova teza američkog sociologa Džoela Besta i njegova analiza urbane legende o prazniku Halovin dali su model za proučavanje tri masovne panike i dve urbane legende. Razmatrane tri panike čine: masovni zbeg usled proročanstva o zemljotresu koji će uništiti Kraljevo, masovni strah od kradljivaca organa u tri sremska sela i šabačka panika usled pojave 'kanibalističke sekte', dok se dve urbane legende odnose na bogatog starog iseljenika koga je dete iz siromašne porodice upoznalo slučajno okrećući brojeve telefona i kradljivog poštara koji je ukradenim penzijama započeo biznis u Rusiji.The constructionist approach to social problems has developed a thesis about mass panics and urban legends as 'unconstructed social problems'. This thesis, advanced by the American sociologist Joel Best, and his analysis of the urban legend of Halloween sadism, have provided the model for studying three mass panics and two urban legends. The three panics in question are the mass exodus from Kraljevo because of a prophesy that the town would be destroyed in an earthquake, the mass fear of body parts thieves in three villages in Srem, and the panic over the appearance of a cannibal sect in the town of Šabac. The two urban legends involve the rich old emigrant whose acquaintance a child from a poor family made while dialing phone numbers at random, and the thieving postman who set up his own business in Russia with the stolen pension money he had been supposed to deliver

Ten Antitheses to a Post-ism in Anthropology

This paper challenges the conception that postmodernism can only be described in postmodernist terms. I claim that theory of ethnography was never part of general anthropological methodology. Furthermore - despite numerous efforts - it never was nor will be a theory at all, but only a discussion of techniques of data collection. Once we formulate the problem, find a location in time and space in which it can best betested, and confront our hypotheses with either corroborating or falsifying facts, we will be able to abandon the idea - that was being grounded both in American anthropology and Serbian ethnology for centuries - that science begins with collecting facts. Gathering around the already weakened anthropological center would enable us to comprehend the disciplinary damage from wasting very limited human resources. Therefore, I plead for the concentration around the core of anthropology, which is already so vast that it barely allows our discipline.Teza da se o postmodernizmu može pisati samo postmoder-nističkim jezikom je netačna.'Teorija'' etnografije nije nikada ni spadala u opštu antropološku metodologiju, i, što je manje važno, nikada nije bila teorija, a neće ni biti ma koliko se mnogi trudili, već samo rasprava o tehnikama prikupljanja podataka. Kada se formuliše problem i potraži lokacija u vremenu i prostoru na kojoj se on najbolje očitava i hipoteze suoče sa činjenicama koje je potvrđuju ili obaraju, napušta se u američkoj antropologiji i srpskoj etnologiji vekovima uvreženo shvatanje da nauka počinje sakupljanjem činjenica.Zbijanje redova oko ionako veoma raznovrsnog antropološkog jezgra ukazuje na disciplinarnu štetu od rasipanje veoma ograničenih ljudskih resursa i pledira za koncentrisanje oko antropološkog jezgra, koje je toliko da jedva omogućava disciplinarnu prepoznatljivost

Modernism and structuralism: Serbian ethnology/anthropology in the last twenty five years of the twentieth century

Modernizaciju srpske etnologije/antropologije u poslednjoj četvrtini XX veka obeležio je strukturalizam. Preciznije rečeno, strukturalna analiza, kojom je etabliran imperativ interpretacije, generisana je iz dela Klod Levi-Strosa zatim preteča strukturalne analize (Van Genepa i Propa) ili iz britanske recepcije strukturalizma (E.Lič, M.Daglas), kao i ruske semiotičke škole ili Bartovske semiologije. Izuzimajući preteče strukturalne analize, svi glavni izvori srpske strukturalno-semiološke revolucije potiču iz Levi-Strosove strukturalne antropologije. Kada, oko 1970 godine, iz intelektualnog okruženja stižu pred domaćeg čitaoca antropološke knjige iz glavnih teorijskih pravaca dvadesetog veka, srpska etnologija je, budući tabula rasa nastala jednovekovnom ukorenjenošću u romantičarske osnove svog nastanka davala jednake šanse svima. Ovaj tekst će pokušati da odgovori na pitanje zašto je baš strukturalna analiza odigrala modernizacijsku ulogu u srpskoj etnologiji/antropologiji, dok su ideje funkcionalizma, proučavanja kulture i ličnosti ili neoevolucionistički pravac ostali bez dubokog i prevratničkog uticaja.Modernisation of Serbian ethnology/anthropology in the second quarter of the twentieth century was marked by structuralism. More precisely, structural analysis that became a must of the analytical interpretation was based on the work of Claude Levi-Strauss, but also on those of the predecessors of structural analysis, like Van Gennep and Prop; British followers of structuralism like E. Leach and M. Douglas, as well as on the Russian semiotic school and Barth's semiology. Taking aside predecessors of structural analysis, main sources of Serbian structural-semiotic revolution came from Levi-Strauss structural anthropology. When in the 1970s Serbian readers faced anthropological books coming from different intellectual backgrounds and representing major theoretical trends in anthropology Serbian ethnology, firmly based on its hundred years old romantic roots, gave equally opportunities to all theoretical approaches that fought for the intellectual domination in the discipline. This paper tries to answer the question why structural analysis played a crucial part in the modernisation of Serbian ethnology/anthropology, while the ideas coming from functionalism culture and personality school, or neo-evolutionism did not have the same revolutionary and deep impact

Neurochemical and Behavioural Changes in Rat Models of Depression

Depression is one of the most prevalent psychiatric disorders with significant lifetime prevalence. The study of human depression is hindered by the relatively significant heterogeneity of this disorder. As a result of these heterogeneities, studies using a sound and representative animal model of depression are extremely valuable and, in general, provide important information regarding the neurochemical/ biological changes occurring during depression and the subsequent treatment of its symptoms. In this review we concentrate on two solid rat models of depression: olfactory bulbectomized (OBX) rats and Flinders Sensitive Line (FSL) of rats. These two models were selected because they possess all three characteristics of a good animal model; face, predictive and constructive validities. We also emphasize the brain serotonergic system and we discuss the open field and forced swim test to assess behaviour. (doi: 10.5562/cca1817

Penkala Airplane Replica Aerodynamic Coefficients Calculation

Replika Penkalinog zrakoplova konstruirana je za stogodišnjicu zrakoplovstva u Hrvatskoj 2010. godine. Uspješno je obavila svoj prvi let, a nakon toga je svega nekoliko puta letjela. Naime, zapaženi su problemi u letu koji bi se trebali otkloniti kako bi let bio stabilan i siguran. U procesu usavršavanja tog zrakoplova potrebno je odrediti aerodinamičke koeficijente koji nikad nisu računati za cjelokupni zrakoplov što će biti napravljeno u ovome radu. Proračunat će se aerodinamički koeficijenti uzgona CL, induciranog otpora CDi jer se promatra bezvrtložno nestlačivo strujanje neviskoznog fluida te koeficijent momenta propinjanja Cm. Za analizu zrakoplova korišten je programski paket XFLR5 koji je osmišljen za analizu aeroprofila, krila i zrakoplova na malim Reynoldsovim brojevima. Zbog nedovoljnog poznavanja mogućnosti i točnosti navedenog paketa, dobiveni rezultati za aeroprofil i krilo bit će uspoređeni s rezultatima dobivenim jednakim metodama u programskom paketu MATLAB upotrebom znanja stečenih na kolegiju Aerodinamika 1 na studiju Zrakoplovstva Fakulteta Strojarstva i brodogradnje, Sveučilišta u Zagrebu. Metoda korištena za analizu aeroprofila je tzv. panelna metoda, dok su metode korištene za proračun ostatka zrakoplova: Prandtlova metoda noseće linije, Vortex Lattice Metoda i 3D panelna metoda. Analiza je provedena tako da se vidi utjecaj pojedine komponente zrakoplova na promatrane aerodinamičke koeficijente. Razmatrat će se aeroprofil, krilo, krilo i trup te naposlijetku cjelokupna konfiguracija zrakoplova koja se sastoji od krila, trupa i repa. Aerodinamički koeficijenti prikazani su dijagramski uz polinome koji opisuju krivulje na dijagramima.A replica of Penkala's airplane was designed for the centenary of Croatian aviation in 2010. Its maiden flight was successful, but it has flown few times since. Several problems were detected during the flight, which must be removed for stable and safe future flying. For further airplane development it is necessary to calculate aerodynamic coefficients which have never before been calculated for the entire airplane. That is precisely what will be done in this thesis. Within steady uniform flow of incompressible fluid the airplane will be observed and lift CL, induced drag CDi and pitching Cm coefficients will be calculated. XFLR5 software will be used for the analysis. It is a tool for analysing airfoils, wings and planes operating at low Reynolds numbers. The lack of knowledge of this software was taken into consideration, and for this reason the results for the airfoil and wing will be compared with the results calculated by MATLAB software with codes learnt at Aerodynamic 1 course at the Faculty of Mechanical Engineering and Naval Architecture at the University of Zagreb. The method used for the airfoil analysis is the panel method, while the methods used for the analysis of the rest of the airplane are: Lifting Line Theory, Vortex Lattice Method and 3D Panel method. The analysis was conducted in a way to detect the influence of each component of the airplane on aerodynamic coefficients. The observed components are the airfoil, wing, wing and body, and at last the entire configuration of the airplane, composed of the wing, body and tail. Aerodynamic coefficients are shown in diagrams and supported by polynomials that describe curves on diagrams