Polytopal Bier spheres and Kantorovich-Rubinstein polytopes of weighted cycles

The problem of deciding if a given triangulation of a sphere can be realized as the boundary sphere of a simplicial, convex polytope is known as the "Simplicial Steinitz problem". It is known by an indirect and non-constructive argument that a vast majority of Bier spheres are non-polytopal. Contrary to that, we demonstrate that the Bier spheres associated to threshold simplicial complexes are all polytopal. Moreover, we show that all Bier spheres are starshaped. We also establish a connection between Bier spheres and Kantorovich-Rubinstein polytopes by showing that the boundary sphere of the KR-polytope associated to a polygonal linkage (weighted cycle) is isomorphic to the Bier sphere of the associated simplicial complex of "short sets"

Bias in memory of war in Croatia (1991-1995): psychological processes in the creation of historical narratives

Međuetnički sukobi nemaju za posledicu isključivo ljudske žrtve i materijalna stradanja, već i trvenja oko razumevanja njegovih uzroka i učesnika. U ovim situacijama, uverenje da je „naše” tumačenje istorije pravo tumačenje se manifestuje kroz različite pokušaje nametanja verzije prošlosti koja odgovara interesima sopstvene grupe – prošlost sada postaje „arena” u kojoj se nacije sukobe na simboličkom planu. U našem istraživanju, hteli smo da proverimo koliko su ovi stavovi izraženi prilikom analize dva postkonfliktna društva – Srbije i Hrvatske, na temu skorašnje istorije sukoba tj. rata u Hrvatskoj 1991-1995 godine. Osnovni cilj ovog rada jeste bila analiza pokazatelja pristrasnosti u istorijskim narativima o skorašnjoj istoriji sukoba i proučavanje psihičkih faktora koji pojedinca motivišu da zastupa jednostrane predstave prošlosti. Sproveli smo tri studije različite opštosti. Prva studija je podrazumevala sistematski pregled literature o udžbeničkim pristrasnostima na prostoru Srbije i Hrvatske, kao i analizu sadržaja testova znanja i nastavnih planova i programa. Pokazali smo kako se obrazovno institucionalizovani narativi u ove dve države nalaze u krugu međusobnog opovrgavanja, kroz delegitimizaciju suparničke etničke grupe i naglasku na sopstvena stradanja. Druga studija je zamišljena kao komparacija srpskog i hrvatskog uzorka kroz sistematizaciju postojećih nalaza o remetilačkom uticaju pojedinih antagonističkih uverenja. Pružili smo model koji se adekvatno pokazao na oba etnička poduzorka i ukazali smo na najznačajnije psihičke faktore koji stoje u osnovi zastupanja jednostranih istorijskih narativa. Na kraju, treću studiju smo sproveli kako bismo pružili kauzalnu potvrdu za naš model. Podaci su dosledno potvrdili uticaj sržnih elemenata modela na stepen prihvatanja informacija koje su u skladu sa uvreženim (i pristrasnim) istorijskim narativom. Na kraju, posebnu pažnju smo posvetili implikacijama nalaza za postojeću literaturu, ograničenjima našeg istraživanja i smernicama za buduće studije.Consequences of inter-ethnic conflicts are not constrained to human casualties and material suffering, but also include frictions regarding the understanding of its causes and participants. In these situations, the belief that "our" interpretation of history is the right interpretation manifests itself through various attempts to impose a version of the past that suits the interests of one's own group – the past becomes an "arena" in which nations clash on a symbolic level. In our research, we wanted to examine how much are these ideas present in our analysis of two post-conflict societies – Serbia and Croatia, regarding the recent conflict, i.e. war in Croatia (1991-1995). The main goal of this work was the analysis of indicators of bias in historical narratives about the recent history of the conflict and the study of psychological factors that motivate an individual to represent one-sided representations of the past. We conducted three studies of varying generality. The first study included a systematic review of the literature on textbook bias in Serbia and Croatia, as well as content analysis of graduation and entrance tests and curricula. We have shown how the educationally institutionalized narratives in these two countries are in a circle of mutual refutation, through the delegitimization of the rival ethnic group and the emphasis on in-group suffering. The second study was conceived as a comparison of the Serbian and Croatian samples through the systematization of existing findings regarding the disruptive influence of certain antagonistic beliefs. We provided a model that proved adequate for both ethnic sub-samples and we pointed out the most significant psychological factors underlying the level of acceptance of one-sided historical narratives. Finally, we conducted a third study to provide causal validation of our model. The data consistently confirmed the influence of the core model elements on the degree of acceptance of information that is consistent with the entrenched (and biased) historical narrative. Finally, we provided particular attention to the implications of the findings for the existing literature, limitations of our research and directions for future studies. Keywords: historical narratives, educational institutionalization of memories, moral exclusion, conflict ethos, FENC

Polytopality of simple games

The Bier sphere $Bier(\mathcal{G}) = Bier(K) = K\ast_\Delta K^\circ$ and the canonical fan $Fan(\Gamma) = Fan(K)$ are combinatorial/geometric companions of a simple game $\mathcal{G} = (P,\Gamma)$ (equivalently the associated simplicial complex $K$), where $P$ is the set of players, $\Gamma\subseteq 2^P$ is the set of wining coalitions, and $K = 2^P\setminus \Gamma$ is the simplicial complex of losing coalitions. We characterize roughly weighted majority games as the games $\Gamma$ such that $Bier(\mathcal{G})$ (respectively $Fan(\Gamma)$) is canonically polytopal (canonically pseudo-polytopal) and show, by an experimental/theoretical argument, that all simple games with at most five players are polytopal

Pebble dynamics and accretion onto rocky planets. II. Radiative models

We investigate the effects of radiative energy transfer on a series of nested-grid, high-resolution hydrodynamic simulations of gas and particle dynamics in the vicinity of an Earth-mass planetary embryo. We include heating due to the accretion of solids and the subsequent convective motions. Using a constant embryo surface temperature, we show that radiative energy transport results in a tendency to reduce the entropy in the primordial atmosphere, but this tendency is alleviated by an increase in the strength of convective energy transport, triggered by a correspondingly increased super-adiabatic temperature gradient. As a consequence, the amplitude of the convective motions increase by roughly an order of magnitude in the vicinity of the embryo. In the cases investigated here, where the optical depth towards the disk surface is larger than unity, the reduction of the temperature in the outer parts of the Hill sphere relative to cases without radiative energy transport is only $\sim$100K, while the mass density increase is on the order of a factor of two in the inner parts of the Hill sphere. Our results demonstrate that, unless unrealistically low dust opacities are assumed, radiative cooling in the context of primordial rocky planet atmospheres can only become important after the disk surface density has dropped significantly below minimum-mass-solar-nebula values.Comment: 5 pages, 4 figures, 2 appendices; MNRAS Letters, accepte

Human Resource Management Between Economy and Ethics – Research of Serbia and Bosnia and Hercegovina

This paper discusses economic and ethical issues that bring about certain limitations in human resource management as one of the basic organizational functions, through which the organization’s relationship with employees is expressed. The aim of this paper is to point out the ethical dimension of human resource management as a key organizational function, which has economic, but at the same time ethical responsibilities. In elaborating this problem, we started from the basic assumption that human resource management as an organizational function and theoretical concept should balance between economic and ethical requirements, which depends on the attitudes of managers as decision makers. In addition to the analysis of the existing literature in this field, an empirical research was conducted to verify the stated assumptions on the basis of a survey questionnaire, which explored the attitudes of managers

Vidni natur beton: svojstva, primena i tehnička regulativa

Different aspects of exposed concrete application are discussed in this paper. Short historical review of exposed concrete application in Belgrade area and in Serbia is presented. Also, special attention is paid to the problems related to construction and exploitation of exposed concrete structures. The significance of formwork's type and quality is also underlined. The review of relevant technical regulation covering this area is given. Finally, conclusions related to possible application of exposed concrete in contemporary civil engineering are derived

FIBER REINFORCED CEMENT COMPOSITES-IMPROVEMENT OF MECHANICAL AND DEFORMATION PROPERTIES

This paper presents the results of authors' laboratory testing of the influence of steel fibers as fiber reinforcement on the change of properties of cement composite mortar and concrete type materials.Mixtures adopted - compositions of mortars had identical amounts of components: cement, sand and silica fume. The second type of mortar contained 60 kg/m3 of fiber reinforcement, as well as the addition of the latest generation of superplasticizer. Physical and mechanical properties of fiber reinforced mortars and etalon mixtures (density, flexural strength, compressive strength) were compared. Tests on concrete type cement composites included: density, mechanical strengths and deformation properties. The results showed improvement in the properties of fiber reinforced composite

Photoinduced processes, radiation interaction with material and damages - material hardness

Photo and nuclear radiation induced processes are considered through the interaction of radiation with semiconducting, metallic and other materials, including the scintillator materials. The improvement of component efficiency by the use of quantum generators, trimming and hybrid processes with nuclear radiation has been analyzed. The studied processes can be positive or negative depending on application. Besides the experimental approach to the processes and chosen interactions, the analytical description of our experiments, as well as ones from other references, has been performed. The contemporary couplings between the nuclear physics, laser techniques and respective dosimetric aspects have been considered