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3,111 results on '"Zalar, A."'

1. Construction of exceptional copositive matrices

Author

Štrekelj, Tea and Zalar, Aljaž

Subjects
Mathematics - Functional Analysis, 13J30, 47L07, 52A40 (Primary), 90C22, 90C27 (Secondary)
Abstract

An $n\times n$ symmetric matrix $A$ is copositive if the quadratic form $x^TAx$ is nonnegative on the nonnegative orthant $\mathbb{R}^{n}_{\geq 0}$. The cone of copositive matrices contains the cone of matrices which are the sum of a positive semidefinite matrix and a nonnegative one and the latter contains the cone of completely positive matrices. These are the matrices of the form $BB^T$ for some $n\times r$ matrix $B$ with nonnegative entries. The above inclusions are strict for $n\geq5.$ The first main result of this article is a free probability inspired construction of exceptional copositive matrices of all sizes $\geq 5$, i.e., copositive matrices that are not the sum of a positive semidefinite matrix and a nonnegative one. The second contribution of this paper addresses the asymptotic ratio of the volume radii of compact sections of the cones of copositive and completely positive matrices. In a previous work by the authors, it was shown that, by identifying symmetric matrices naturally with quartic even forms, and equipping them with the $L^2$ inner product and the Lebesgue measure, the ratio of the volume radii of sections with a suitably chosen hyperplane is bounded below by a constant independent of $n$ as $n$ tends to infinity. In this paper, we extend this result by establishing an analogous bound when the sections of the cones are unit balls in the Frobenius inner product., Comment: 12 pages. arXiv admin note: substantial text overlap with arXiv:2305.16224

Published
2025

2. Bivariate Truncated Moment Sequences with the Column Relation $XY=X^m + q(X)$, with $q$ of degree $m-1$

Author

Yoo, Seonguk and Zalar, Aljaz

Subjects
Mathematics - Functional Analysis, Primary 47A57, 44A60, Secondary 15-04, 47A20, 32A60
Abstract

When the algebraic variety associated with a truncated moment sequence is finite, solving the moment problem follows a well-defined procedure. However, moment problems involving infinite algebraic varieties are more complex and less well-understood. Recent studies suggest that certain bivariate moment sequences can be transformed into equivalent univariate sequences, offering a valuable approach for solving these problems. In this paper, we focus on addressing the truncated moment problem (TMP) for specific rational plane curves. For a curve of general degree we derive an equivalent Hankel positive semidefinite completion problem. For cubic curves, we solve this problem explicitly, which resolves the TMP for one of the four types of cubic curves, up to affine linear equivalence. For the quartic case we simplify the completion problem to a feasibility question of a three-variable system of inequalities.

Published
2024

3. Gaussian Quadratures with prescribed nodes via moment theory

Author

Nailwal, Rajkamal and Zalar, Aljaž

Subjects
Mathematics - Functional Analysis, Mathematics - Numerical Analysis, 65D32, 47A57, 47A20, 44A60 (Primary), 15A04, 47N40 (Secondary)
Abstract

Let $\mu$ be a positive Borel measure on the real line and let $L$ be the linear functional on univariate polynomials of bounded degree, defined as integration with respect to $\mu$. In 2020, Blekherman et al., the characterization of all minimal quadrature rules of $\mu$ in terms of the roots of a bivariate polynomial is given and two determinantal representations of this polynomial are established. In particular, the authors solved the question of the existence of a minimal quadrature rule with one prescribed node, leaving open the extension to more prescribed nodes. In this paper, we solve this problem using moment theory as the main tool., Comment: 14 pages

Published
2024

4. The truncated univariate rational moment problem

Author

Nailwal, Rajkamal and Zalar, Aljaž

Subjects
Mathematics - Functional Analysis, Primary 47A57, 47A20, 44A60, Secondary 15A04, 47N40
Abstract

Given a closed subset $K$ in $\mathbb{R}$, the rational $K$-truncated moment problem ($K$-RTMP) asks to characterize the existence of a positive Borel measure $\mu$, supported on $K$, such that a linear functional $\mathcal{L}$, defined on all rational functions of the form $\frac{f}{q}$, where $q$ is a fixed polynomial with all real zeros of even order and $f$ is any real polynomial of degree at most $2k$, is an integration with respect to $\mu$. The case of a compact set $K$ was solved by Chandler in 1994, but there is no argument that ensures that $\mu$ vanishes on all real zeros of $q$. An obvious necessary condition for the solvability of the $K$-RTMP is that $\mathcal{L}$ is nonnegative on every $f$ satisfying $f|_{K}\geq 0$. If $\mathcal{L}$ is strictly positive on every $0\neq f|_{K}\geq 0$, we add the missing argument from Chandler's solution and also bound the number of atoms in a minimal representing measure. We show by an example that nonnegativity of $\mathcal{L}$ is not sufficient and add the missing conditions to the solution. We also solve the $K$-RTMP for unbounded $K$ and derive the solutions to the strong truncated Hamburger moment problem and the truncated moment problem on the unit circle as special cases., Comment: 18 pages

Published
2024

5. Extreme values of the mass distribution associated with $d$-quasi-copulas via linear programming

Author

Belšak, Matej, Omladič, Matjaž, Vuk, Martin, and Zalar, Aljaž

Subjects
Mathematics - Statistics Theory, 62H05, 60A99, 60E05, 26B35
Abstract

The recent survey published in Fuzzy Sets and Systems nicknamed ``Hitchhiker's Guide'' has raised the rating of quasi-copula problems in the dependence modeling community in spite of the lack of statistical interpretation of quasi-copulas. Some of the open problems listed there were solved, and some conjectured one way or the other. This paper concentrates on the Open Problem 5 of this list concerning bounds on the volume of a $d$--variate quasi-copula. We disprove a recent conjecture published in the same journal on the lower bound of this volume. We also give evidence that the problem is much more difficult than suspected and provide hints about its final solution., Comment: 17 pages, 1 figure, 4 tables

Published
2024

6. Enhanced Instructional and Professional Growth through a Pragmatic Instructional Approach

Author

Joanna C. Weaver, Gabriel T. Matney, Chloe Beeker, and Alex Zalar

Abstract

Finding a pragmatic process across university programs and disciplines that has the potential to strengthen programs and instruction has promise for adoption because of the possible impact and benefits. Jigsaw Lesson Study (JLS) has that potential and could be expanded into not only a teacher-education classroom but also into any discipline across a university campus. JLS offers opportunities for student engagement and professional development. Here, we used the JLS process, modified from Lesson Study (LS), to strengthen instructional decision-making, lesson planning, and student learning in a teacher-education course. We sought to determine the impact of JLS on teacher candidates' professional growth. We determined that when participating in the JLS process, teacher candidates engaged more fully in their subject areas, grew as collaborative educators, and developed a heightened awareness of how students learn.

Published
2024

7. The truncated moment problem on reducible cubic curves I: Parabolic and Circular type relations

Author

Yoo, Seonguk and Zalar, Aljaž

Subjects
Mathematics - Functional Analysis, Primary 44A60, 47A57, 47A20, Secondary 15A04, 47N40
Abstract

In this article we study the bivariate truncated moment problem (TMP) of degree $2k$ on reducible cubic curves. First we show that every such TMP is equivalent after applying an affine linear transformation to one of 8 canonical forms of the curve. The case of the union of three parallel lines was solved in 2022 by the second author, while the degree 6 cases in 2017 by the first author. Second we characterize in terms of concrete numerical conditions the existence of the solution to the TMP on two of the remaining cases concretely, i.e., a union of a line and a circle $y(ay+x^2+y^2)=0, a\in \mathbb{R}\setminus \{0\}$, and a union of a line and a parabola $y(x-y^2)=0$. In both cases we also determine the number of atoms in a minimal representing measure., Comment: 45 pages

Published
2024

8. Cross-positive linear maps, positive polynomials and sums of squares

Author

Klep, Igor, Šivic, Klemen, and Zalar, Aljaž

Subjects
Mathematics - Functional Analysis, 13J30, 15B48, 46L07, 47D06, 52A40 (Primary), 47L25, 90C22 (Secondary)
Abstract

A linear map $\Phi$ between matrix spaces is called cross-positive if it is positive on orthogonal pairs $(U,V)$ of positive semidefinite matrices in the sense that $\langle U,V\rangle:=\text{Tr}(UV)=0$ implies $\langle \Phi(U),V\rangle\geq0$, and is completely cross-positive if all its ampliations $I_n\otimes \Phi$ are cross-positive. (Completely) cross-positive maps arise in the theory of operator semigroups, where they are sometimes called exponentially-positive maps, and are also important in the theory of affine processes on symmetric cones in mathematical finance. To each $\Phi$ as above a bihomogeneous form is associated by $p_\Phi(x,y)=y^T\Phi(xx^T)y$. Then $\Phi$ is cross-positive if and only if $p_\Phi$ is nonnegative on the variety of pairs of orthogonal vectors $\{(x,y)\mid x^Ty=0\}$. Moreover, $\Phi$ is shown to be completely cross-positive if and only if $p_\Phi$ is a sum of squares modulo the principal ideal $(x^Ty)$. These observations bring the study of cross-positive maps into the powerful setting of real algebraic geometry. Here this interplay is exploited to prove quantitative bounds on the fraction of cross-positive maps that are completely cross-positive. Detailed results about cross-positive maps $\Phi$ mapping between $3\times 3$ matrices are given. Finally, an algorithm to produce cross-positive maps that are not completely cross-positive is presented., Comment: 42 pages

Published
2024

10. A random copositive matrix is completely positive with positive probability

Author

Klep, Igor, Štrekelj, Tea, and Zalar, Aljaž

Subjects
Mathematics - Functional Analysis, Mathematics - Optimization and Control, Quantum Physics, 13J30, 47L07, 52A40 (Primary), 90C22, 90C27 (Secondary)
Abstract

An $n\times n$ symmetric matrix $A$ is copositive if the quadratic form $x^TAx$ is nonnegative on the nonnegative orthant. The cone of copositive matrices strictly contains the cone of completely positive matrices, i.e., all matrices of the form $BB^T$ for some (possibly rectangular) matrix $B$ with nonnegative entries. The main result, proved using Blekherman's real algebraic geometry inspired techniques and tools of convex geometry, shows that asymptotically, as $n$ goes to infinity, the ratio of volume radii of the two cones is strictly positive. Consequently, the same holds true for the ratio of volume radii of any two cones sandwiched between them, e.g., the cones of positive semidefinite matrices, matrices with nonnegative entries, their intersection and their Minkowski sum., Comment: 27 pages. A major rewrite with the addition of applications and detailed discussions on size comparison of cones. The part with the construction of examples will appear in a separate paper

Published
2023
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11. Investigating the synergistic impact of freeze-thaw cycles and deicing salts on the properties of cementitious composites incorporating natural fibers and fly ash

Author

Ildiko Merta, Vesna Zalar Serjun, Alenka Mauko Pranjić, Aljoša Šajna, Mateja Štefančič, Bojan Poletanović, Farshad Ameri, and Ana Mladenović

Subjects
Cementitious composites, Natural fibers, Freeze-thaw cycles, Mechanical properties, Mass loss, Fly ash, Renewable energy sources, TJ807-830, Environmental engineering, TA170-171
Abstract

In cold climates, concrete structures confront durability challenges due to harsh conditions. This study evaluates the effects of incorporating natural fibers, such as hemp and flax fibers (at 1 vol%), and partially replacing cement with fly ash (at 25 and 50 wt%) on the properties of cementitious composites subjected to accelerated aging under freeze-thaw cycles and deicing salts.Findings reveal that natural fibers enhance the freeze-thaw resistance, reducing deterioration (scaling) to 5–8% after 56 cycles. When mortars were subjected to accelerated freeze-thaw cycles, the compressive strength of plain mortar significantly decreased (up to 57%). However, adding natural fibers to the matrix substantially reduced its compressive strength loss. In the case of flexural strength, plain mortars experienced 33% loss, while hemp, flax, and polypropylene fiber mortars showed only 13%, 23%, and 10% losses, respectively. Furthermore, mortars experience a notable enhancement in their energy absorption capacity when reinforced with natural fibers, particularly with hemp fibers (up to 348% higher than plain mortar).Under harsh conditions, hemp and flax-reinforced mortars, with 25 wt% fly ash replacement, lose the compressive strength significantly however still demonstrate an alternative to synthetic fibers in terms of flexural strength. Even with 25 wt% of fly ash, mortars with natural fiber reinforcement display significantly superior energy absorption capacities compared to plain mortars (up to 48%).

Published
2025
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12. The truncated moment problem on curves $y=q(x)$ and $yx^\ell=1$

Author

Zalar, Aljaž

Subjects
Mathematics - Functional Analysis, Primary 44A60, 47A57, 47A20, Secondary 15A04, 47N40
Abstract

In this paper we study the bivariate truncated moment problem (TMP) on curves of the form $y=q(x)$, $q(x)\in \mathbb{R}[x]$, $\text{deg } q\geq 3$, and $yx^\ell=1$, $\ell\in \mathbb{N}\setminus\{1\}$. For even degree sequences the solution based on the number of moment matrix extensions was first given by Fialkow using the truncated Riesz-Haviland theorem and a sum-of-squares representations for polynomials, strictly positive on such curves. Namely, the upper bound on this number is quadratic in the degrees of the sequence and the polynomial determining a curve. We use a reduction to the univariate setting technique and improve Fialkow's bound to $\text{deg }q-1$ (resp. $\ell+1$) for curves $y=q(x)$ (resp. $yx^\ell=1$). This in turn gives analogous improvements of the degrees in the sum-of-squares representations referred to above. Moreover, we get the upper bounds on the number of atoms in the minimal representing measure, which are $k\;\text{deg }q$ (resp. $k(\ell+1)$) for curves $y=q(x)$ (resp. $yx^\ell=1$) for even degree sequences, while for odd ones they are $k\;\text{deg }q-\big\lceil\frac{\text{deg }q}{2} \big\rceil$ (resp. $k(\ell+1)-\big\lfloor\frac{\ell}{2} \big\rfloor+1$) for curves $y=q(x)$ (resp. $yx^\ell=1$). In the even case these are counterparts to the result by Riener and Schweighofer, which gives the same bound for odd degree sequences on all plane curves, while in the odd case it is a slight improvement of their bound in these special cases. Further on, we give another solution to the TMP on the curves studied based on the feasibility of a linear matrix inequality, corresponding to the univariate sequence obtained, and finally we solve concretely odd degree cases of the TMP on curves $y=x^\ell$, $\ell=2,3$, and add a new solvability condition to the even degree case on the curve $y=x^2$., Comment: 40 pages; To appear in Linear and Multilinear Algebra

Published
2022

14. Incidence and risk factors for thromboembolic events in pediatric-onset inflammatory bowel disease: A French population-based study

Author

Najib, AL GHOSSAINI, Raied, AL HAMEEDI, Saria, AL TURK, Eric, AGOUTE, Matthieu, ANTOINE, Michel, ANTONIETTI, Amar, AOUAKLI, Laura, ARMENGOL-DEBEIR, Ibrahim, AROICHANE, Fadi, ASSI, Eric, AUXENFANTS, Kassem, AZZOUZI, Damyan, BANKOVSKI, Bernard, BARBRY, Nicolas, BARDOUX, Philippe, BARON, Agnès, BAUDET, Pauline, BAYART, Brice, BAZIN, Arash, BEBAHANI, Jean-Pierre, BECQWORT, Sara, BELLATI, Vincent, BENET, Houssem, BEN ALI, Coralie, BENARD, Corinne, BENGUIGUI, Emmanuel, BEN SOUSSAN, Abdeslam, BENTAL, Jacques, BERNET, Karine, BERNOU, Pauline, BERTOT, Nathalie, BERTIAUX-VANDAËLE, Valérie, BERTRAND, Emilie, BILLOUD, Nathalie, BIRON, Benjamin, BISMUTH, Cyril, BLANCHARD, Fabienne, BLONDEL, Valérie, BLONDIN, Marius, BOBULA, Philippe, BOHON, Eléonore, BOIVIN, Vanessa, BON DJEMAH, Eric, BONIFACE, Philippe, BONNIÈRE, Arnaud, BORUCHOWICZ, Médina, BOUALIT, Ahlem, BOUAZZA, Bruno, BOUCHE, Claude, BOURGEAUX, Morgane, BOURGEOIS-FUMERY, Arnaud, BOURGUET, Hamza, BOUTALEB, Alexis, BOUTHORS, Julien, BRANCHE, Frank, BRAZIER, Marie, BRIDENNE, Hélène, BRIHIER, Laura, BRIL, Maud, BRUNG-LEFEBVRE, Philippe, BULOIS, Pierre, BURGIERE, Joël, BUTEL, Valérie, CANVA-DELCAMBRE, Florence, CARDOT, Sandrine, CARETTE, Pierre, CARPENTIER, Jean-François, CASSAR, Michel, CASSAGNOU, François, CASTEX, Pascale, CATALA, Stéphane, CATTAN, Sylviane, CATTEAU, Bernard, CAUJOLLE, Cloé, CHARPENTIER, Marthe, CHAVANCE-THELU, Agathe, CHENY, Antoire, CHOTEAU, Pierre-Yves, CLERGUE, Hugues, COEVOET, Gil, COHEN, Régis, COLLET, Marie, COLIN, Jean-Frederic, COLOMBEL, Stéphanie, COOPMAN, Lucie, CORDIEZ, Jean, CORVISART, Antoine, CORTOT, Frédéric, COUTTENIER, Valérie, CROMBE, Abdelhakim, DAOUDI, Vincent, DAPVRIL, Thierry, DAVION, Sébastien, DECOSTER, Aurélien, DEJAEGER, Richard, DELCENSERIE, Marine, DELEPLANQUE, Dorothée, DELESALLE, Olivier, DELETTE, Thierry, DELGRANGE, Laurence, DELHOUSTAL, Jean-Stéphane, DELMOTTE, Sabri, DEMMANE, Guy, DEREGNAUCOURT, Pierre, DESECHALLIERS Jean, Patrick, DESMET, Pierre, DESREUMAUX, Gérard, DESSEAUX, Philippe, DESURMONT, Alain, DEVIENNE, Eve, DEVOUGE, Alex, DEVROUX, Arnaud, DEWAILLY, Sébastien, DHARANCY, Aude, Djamal-Dine, DJEDDI, Rachid, DJEDIR, Wissam, DOLEH, Laure, DREHER-DUWAT Marie, Clotilde, DUBURQUE, Frédéric, DUCROT, Philippe, DUCROTTE, André, DUFILHO, Christian, DUHAMEL, Caroline, DUMANT-FOREST, Louis, DUPAS Jean, Frédéric, DUPONT, Yves, DURANTON, Arnaud, DURIEZ, Nicolas, DUVEAU, Khalil, EL ACHKAR, Mohammadi, EL FARISI, Caroline, ELIE, Marie-Claire, ELIE-LEGRAND, Matthieu, EOCHE, Essmaeel, ESSMAEEL, Dominique, EVRARD, Jean-Paul, EVRARD, Armelle, FATOME, Laurent, FINET, Mathilde, FLAHAUT, Camille, FLAMME, David, FOISSEY, Peggy, FOURNIER, Marie-Christine, FOUTREIN-COMES, Philippe, FOUTREIN, Thierry, FRERE, Mathurin, FUMERY, Julie, GALAND, Philippe, GALLAIS, Claudine, GAMBLIN, Serge, GANGA, Romain, GERARD, Salah, GHRIB, Thierry, GILBERT, Denis, GODART, Jean-Michel, GODCHAUX, Guetty, GOEGEBEUR, Odile, GORIA, Frederic, GOTTRAND, Lucien, GRADOS, Brigitte, GRANDMAISON, Marion, GROUX, Claire, GUEDON, Loïc, GUERBEAU, Mathilde, GUEROULT-DERO, Laurence, GUILLEM, François, GUILLEMOT, Dominique, GUIMBER, Baya, HADDOUCHE, Vincent, HAUTEFEUILLE, Geneviève, HECQUET, Jean-Pierre, HEDDE, Pierre-Emmanuel, HENNERESSE, Bruno, HEYMAN, Michel, HERAUD, Sophie, HERVE, Patrick, HOCHAIN, Lucie, HOUSSIN-BAILLY, Philippe, HOUCKE, Bruno, HUGUENIN, Silviu, IOBAGIU, Shata, ISTANBOLI, Alexsandar, IVANOVIC, Isabelle, IWANICKI-CARON, Eric, JANICKI, Marine, JARRY, Charlotte, JEAN BART, Anne, JOUVENET, Fadi, KATHERIN, André, KERLEVEO, Ali, KHACHFE, Jean, KIRIAKOS, Olivier, KLEIN, Matthieu, KOHUT, Richard, KORNHAUSER, Jean-Eric, LABERENNE, Eric, LACOTTE, Guy, LAFFINEUR, Marine, LAGARDE, Anouck, LAHAYE, Arnaud, LALANNE, Ambroise, LALIEU, Pierre, LANNOY, Michel, LAPRAND, Denis, LAUDE, Rachida, LEBLANC, Stéphane, LECLEIRE, Nathalie, LECLERC, Christian, LE COUTEULX, Pascale, LEFILLIATRE, Céline, LEGRAND, Caroline, LEMAITRE, Philippe, LE MOUEL Jean, Gabriel, LEPEUT, Lucie, LEPILEUR, Elodie, LEPOUTRE-DUJARDIN, Henri, LEROI, Maryvonne, LEROY, Pauline, LE ROY, Benoit, LESAGE, Xavier, LESAGE, Jocelyn, LESAGE, Isabelle, LESCANNE-DARCHIS, Dominique, LESCUT, Bruno, LEURENT, Delphine, LEY, Louise, LIBIER, Julien, LOREAU, Alexandre, LOUVET, Joséphine, LOZINGUEZ, Henri, LUBRET, Damien, LUCIDARME, Jean-Jacques, LUGAND, Denis, MAETZ, Olivia, MANOLACHE, Anne-Bérangère, MARKS-BRUNEL, Charline, MARRE, Eric, MARZLOFF, Philippe, MATHURIN, Jacques, MAUILLON, Vincent, MAUNOURY, Michèle-Ange, MEDAM DJOMO, Chloé, MELCHIOR, Ziad, MELKI, Lofti, METHARI, Franck, MEURISSE, Laurent, MICHAUD, Patricia, MODAINE, Angélique, MONTHE, Loïk, MOREL, Mathilde, MORIN, Eugene, MORTIER Pierre, Olivier, MOUTERDE, Nicolas, MOZZICONACI, Jean, MUDRY, Maria, NACHURY, Dung, NGO Minh, Eric, N'GUYEN KHAC, Bertrand, NOTTEGHEM, Vincent, OLLEVIER, Atika, OURAGHI, Barriza, OUSSADOU, Claire, PAINCHART, Bruno, PARENT, Philippe, PATRIER, Thierry, PAUPARD, Mathieu, PAUWELS, Richard, PETIT, Muriel, PIAT, Sandrine, PIOTTE, Christophe, PLANE, Bernard, PLOUVIER, Pierre, POMMELET, Daniela, POP, Charlotte, PORDES, Gérard, POUCHAIN, Philippe, PRADES, Christophe, PREVOST Jean, Gilles, QUARTIER, Anne-Marie, QUEUNIET, Jean-François, QUINTON, Alain, RABACHE, Sébastien, RATAJCZYK, Nicole, REIX, Thibaud, RENAUT-VANTROYS, Marine, REVILLION, Ghassan, RIACHI, Clémentine, RIAULT, Nicolas, RICHARD, Cécile, RICHEZ, Benoit, RIMBERT, Daniel, RODRIGUEZ Juan, Jean-Marc, ROUX, Alain, RUDELLI, Clémence, SAINGIER, Guillaume, SAVOYE, Patrick, SCHLOSSBERG, David, SEFRIOUI, David, SEGUY, Celik, SEMINUR, Claire, SPYCKERELLE, Nathalie, TALBODEC, Noémie, TAVERNIER, Henriette, TCHANDEU, Aurore, TECHY, Henri, THIEBAULT, Jean-Marie, THOREL, Christophe, THUILLIER, Guillaume, TIELMAN, Manuela, TODE, Jean-Yves, TOUCHAIS, Pierre, TOUMELIN, Yvan, TOUZE, Léa, TRAN, Jean-Luc, TRANVOUEZ, Nadia, TRIKI, Dominique, TURCK, Justine, TURPIN, Stéphanie, UHLEN, Eric, VAILLANT, Claude, VALMAGE, Dominique, VANCO, Nathalie, VANDAELE-BERTIAUX, Hélène, VANDAMME, Etienne, VANDERBECQ, Elise, VANDER EECKEN, Philipe, VANDERMOLEN, Philippe, VANDEVENNE, Lionel, VANDEVILLE, Alain, VANDEWALLE, Jean-Pierre, VANHOOVE, Audrey, VANRENTERGHEM, Charlotte, VANVEUREN, Iona, VASIES, Guy, VERBIESE, Juliette, VERLYNDE, Gwenola, VERNIER-MASSOUILLE, Philippe, VERMELLE, Christine, VERNE, Perrine, VEZILIER-COCQ, Juliette, VIART, Benoit, VIGNERON, Marc, VINCENDET, Jean-Yves, WALLEZ, Michel, WANTIEZ, Faustine, WARTEL, Jean-Christian, WEBER, Jean-Louis, WILLOCQUET, Nathalie, WIZLA, Eric, WOLSCHIES, Oana, ZAHARIA, Sonia, ZAOUI, Alberto, ZALAR, Anne, ZELLWEGER, Richard, Nicolas, Leroyer, Ariane, Ley, Delphine, Dupont, Claire, Bertrand, Valérie, Wils, Pauline, Gower-Rousseau, Corine, Turck, Dominique, Guillon, Nathalie, Sarter, Hélène, Savoye, Guillaume, and Fumery, Mathurin

Published
2025
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15. Incidence, prevalence and clinical presentation of inflammatory bowel diseases in Northern France: a 30-year population-based studyResearch in context

Author

Hélène Sarter, Thibaut Crétin, Guillaume Savoye, Mathurin Fumery, Ariane Leroyer, Luc Dauchet, Thierry Paupard, Hugues Coevoet, Pauline Wils, Nicolas Richard, Dominique Turck, Delphine Ley, Corinne Gower-Rousseau, Eric Agoute, Najib Al Ghossaini, Raied Al Hameedi, Myriam Al Khatib, Saria Al Turk, Jean-Marie Andre, Matthieu Antoine, Michel Antonietti, Amar Aouakli, Laura Armengol-Debeir, Ibrahim Aroichane, Fadi Assi, Eric Auxenfants, Alina Avram, Kassem Azzouzi, Damyan Bankovski, Bernard Barbry, Nicolas Bardoux, Philippe Baron, Anne Baudet, Pauline Bayart, Brice Bazin, Arash Bebahani, Jean-Pierre Becqwort, Houssem Ben Ali, Emmanuel Ben Soussan, Coralie Benard, Vincent Benet, Corinne Benguigui, Abdeslam Bental, Sara Bentaleb-Bellati, Isabelle Berkelmans, Jacques Bernet, Karine Bernou, Nathalie Bertiaux-Vandaele, Pauline Bertot, Valérie Bertrand, Emilie Biloud, Nathalie Biron, Benjamin Bismuth, Cyril Blanchard, Maurice Bleuez, Fabienne Blondel, Valérie Blondin, Marius Bobula, Philippe Bohont, Eléonore Boivin, Vanessa Bon Djemah, Eric Boniface, Philippe Bonniere, Pierre Bonvarlet, Arnaud Boruchowicz, Raoul Bostvironnois, Médina Boualit, Ahlem Bouazza, Bruno Bouche, Christian Boudailler, Claude Bourgeaux, Morgane Bourgeois-Fumery, Arnaud Bourguet, Agnès Bourienne, Hamza Boutaleb, Alexis Bouthors, Julien Branche, Franck Brazier, Marie Bridenne, Hélène Brihier, Laura Bril, Philippe Bulois, Pierre Burgiere, Joël Butel, Jean-Yves Canva, Valérie Canva-Delcambre, Florence Cardot, Sandrine Carette, Pierre Carpentier, Michel Cassagnou, Jean-François Cassar, François Castex, Pascale Catala, Stéphane Cattan, Sylviane Catteau, Bernard Caujolle, Gérard Cayron, Catherine Chandelier, Cloé Charpentier, Marthe Chavance-Thelu, Agathe Cheny, Dinu Chirita, Antoine Choteau, Jean-François Claerbout, Pierre-Yves Clergue, Gil Cohen, Marie Colin, Régis Collet, Jean-Frédéric Colombel, Stéphanie Coopman, Lucie Cordiez, Antoine Cortot, Jean Corvisart, Frédéric Couttenier, Jean-François Crinquette, Valérie Crombe, Abdelhakim Daoudi, Vincent Dapvril, Thierry Davion, Sébastien Decoster, Laurent Defontaine, Nicolas Degrave, Aurélien Dejaeger, Richard Delcenserie, Marine Deleplanque, Dorothée Delesalle, Olivier Delette, Thierry Delgrange, Laurence Delhoustal, Jean-Stéphane Delmotte, Sabri Demmane, Guy Deregnaucourt, Constance Deschepper, Jean-Pierre Desechalliers, Patrick Desmet, Pierre Desreumaux, Gérard Desseaux, Philippe Desurmont, Alain Devienne, Eve Devouge, Alex Devroux, Arnaud Dewailly, Sébastien Dharancy, Aude Di Fiore, Emmanuel Diaz, Djamal-Dine Djeddi, Rachid Djedir, Wissam Doleh, Marie-Laure Dreher-Duwat, Richard Dubois, Clothilde Duburque, Frédéric Ducrot, Philippe Ducrotte, André Dufilho, Christian Duhamel, Caroline Dumant-Forest, Jean-Louis Dupas, Frédéric Dupont, Yves Duranton, Arnaud Duriez, Nicolas Duveau, Mohammadi El Farisi, Khalil El Hachkar, Caroline Elie, Marie-Claire Elie-Legrand, Matthieu Eoche, Essmaeel Essmaeel, Dominique Evrard, Jean-Paul Evrard, Armelle Fatome, Karima Fellah-Sekkai, Bernard Filoche, Laurent Finet, Mathilde Flahaut, Camille Flamme, David Foissey, Peggy Fournier, Philippe Foutrein, Marie-Christine Foutrein-Comes, Thierry Frere, Julie Galand, Philippe Gallais, Claudine Gamblin, Serge Ganga, Romain Gerard, Guillaume Geslin, Yves Gheyssens, Salah Ghrib, Thierry Gilbert, Bénédicte Gillet, Denis Godart, Jean-Michel Godchaux, Guetty Goeguebeur, Odile Goria, Frédéric Gottrand, Philippe Gower, Lucien Grados, Brigitte Grandmaison, Marion Groux, Claire Guedon, Loïc Guerbeau, Mathilde Gueroult-Dero, Jean-François Guillard, Laurence Guillem, François Guillemot, Dominique Guimber, Baya Haddouche, Vincent Hautefeuille, Philippe Hecketsweiller, Geneviève Hecquet, Jean-Pierre Hedde, Hassina Hellal, Pierre-Emmanuel Henneresse, Michel Heraud, Sophie Herve, Bruno Heyman, Patrick Hochain, Philippe Houcke, Lucie Houssin-Baillly, Bruno Huguenin, Silviu Iobagiu, Shata Istanboli, Alexsandar Ivanovic, Isabelle Iwanicki-Caron, Eric Janicki, Marine Jarry, Charlotte Jean Bart, Claude Jonas, Julia Jougon, Anne Jouvenet, Naeim Kassar, Fadi Katherin, Alfred Kerleveo, Ali Khachfe, Alfred Kiriakos, Jean Kiriakos, Olivier Klein, Matthieu Kohut, Richard Kornhauser, Demetrios Koutsomanis, Jean-Eric Laberenne, Eric Lacotte, Guy Laffineur, Marine Lagarde, Anouck Lahaye, Arnaud Lalanne, Ambroise Lalieu, Pierre Lannoy, José Lapchin, Michel Laprand, Denis Laude, Christian Le Couteulx, Charles Le Goffic, Alain Le Grix, Jean-Philippe Le Mouel, Pauline Le Roy, Rachida Leblanc, Paul Lecieux, Stéphane Lecleire, Nathalie Leclerc, Jean Ledent, Jean Lefebvre, Pascale Lefilliatre, Céline Legrand, Patrick Lelong, Bernard Leluyer, Caroline Lemaitre, Lucie Lepileur, Antoine Leplat, Elodie Lepoutre-Dujardin, Gabriel Leppeut, Henri Leroi, Maryvonne Leroy, Benoît Lesage, Jocelyn Lesage, Xavier Lesage, Isabelle Lescanne-Darchis, Dominique Lescut, Bruno Leurent, Michel Lhermie, Louise Libier, Bernard Lisambert, Isabelle Loge, Julien Loreau, Alexandre Louvet, Joséphine Lozinguez, Henri Lubrez, Damien Lucidarme, Jean-Jacques Lugand, Olivier Macaigne, Denis Maetz, Dominique Maillard, Hubert Mancheron, Olivia Manolache, Anne-Bérengère Marks-Brunel, Charline Marre, Raymond Marti, Eric Marzloff, Philippe Mathurin, Jacques Mauillon, Vincent Maunoury, Jean-Luc Maupas, Michèle-Ange Medam Djomo, Chloé Melchior, Ziad Melki, B. Mesnard, Patrice Metayer, Lofti Methari, Franck Meurisse, Laurent Michaud, Patricia Modaine, Angélique Monthe, Loïk Morel, Mathilde Morin, Pierre-Eugène Mortier, Perrine Mortreux, Olivier Mouterde, Nicolas Mozziconaci, Jean Mudry, Maria Nachuri, Minh Dung Ngo, Eric N'guyen Khac, Bertrand Notteghem, Vincent Ollevier, Atika Ouraghi, Barriza Oussadou, Dominique Ouvry, Bernard Paillot, Claire Painchart, Nicole Panien-Claudot, Christian Paoletti, Arsène Papazian, Bruno Parent, Jean-Claude Paris, Philippe Patrier, Bernard Pauwels, Mathieu Pauwels, Richard Petit, Muriel Piat, Sandrine Piotte, Christophe Plane, Bernard Plouvier, Eric Pollet, Pierre Pommelet, Daniela Pop, Charlotte Pordes, Gérard Pouchain, Philippe Prades, Jean-Christophe Prevost, Manon Pruit, Gilles Quartier, Anne-Marie Queuniet, Jean-François Quinton, Alain Rabache, Gilles Raclot, Sébastien Ratajczyk, Nicole Reix, Thibaud Renaut-Vantroys, Marine Revillion, Ghassan Riachi, Clémentine Riault, Cécile Richez, Benoît Rimbert, Philippe Robinson, Juan Daniel Rodriguez, Jean Roger, Jean-Marc Roux, Alain Rudelli, Clémence Saingier, Patrick Schlossberg, David Sefrioui, Michel Segrestin, David Seguy, Célik Seminur, François Sevenet, Jean Silvie, Claire Spyckerelle, Nathalie Talbodec, Noémie Tavernier, Henriette Tchandeu, Aurore Techy, Jean-Luc Thelu, Henri Thiebault, Jean-Marie Thorel, Christophe Thuillier, Guillaume Tielman, Manuella Tode, Jean Tonnel, Jean-Yves Touchais, Audrey Toulemonde-Huguet, Pierre Toumelin, Yvan Touze, Léa Tran, Jean-Luc Tranvouez, Nadia Triki, Justine Turpin, Eric Vaillant, Claude Valmage, Dominique Vanco, Nathalie Vandaele-Bertiaux, Hélène Vandamme, Elise Vander Eeken, Etienne Vanderbercq, Philippe Vandermollen, Philippe Vandevenne, Lionel Vandeville, Alain Vandewalle, Jean-Pierre Vanhoove, Audrey Vanrenterghem, Charlotte Vanveuren, Iona Vasies, Guy Verbiese, Juliette Verlynde, Philippe Vermelle, Christine Verne, Gwenola Vernier-Massouille, Perrine Vezelier-Cocq, Juliette Viart, Benoît Vigneron, Marc Vincendet, Jacques Viot, Y.M. Voiment, Jean-Yves Wallez, Michel Wantier, Faustine Wartel, Jean-Christian Weber, Jean-Louis Willocquet, Nathalie Wizla, Eric Wolschies, Tajiogue Yimfor, Oana Zahara, Alberto Zalar, Sonia Zaoui, and Anne Zellweger

Subjects
Inflammatory bowel disease, Incidence, Prevalence, Population-based registry, Crohn’s disease, Ulcerative colitis, Public aspects of medicine, RA1-1270
Abstract

Summary: Background: In industrialized countries, the incidence of inflammatory bowel disease (IBD) appears stabilized. This study examined the incidence and phenotype of IBD in Northern France over a 30-year period. Methods: Including all IBD patients recorded in the EPIMAD population-based registry from 1988 to 2017 in Northern France, we described the incidence and clinical presentation of IBD according to age, sex and time. Findings: A total of 22,879 incident IBD cases were documented (59% (n = 13,445) of Crohn’s disease (CD), 38% (n = 8803) of ulcerative colitis (UC), 3% (n = 631) of IBD unclassified (IBDU)). Over the study period, incidence of IBD, CD and UC was 12.7, 7.2 and 5.1 per 105 person-years, respectively. The incidence of CD increased from 5.1/105 in 1988–1990 to 7.9/105 in 2015–2017 (annual percent change (APC): +1.9%, p

Published
2024
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17. Collision Milling of Oil Shale Ash as Constituent Pretreatment in Concrete 3D Printing

Author

Lucija Hanžič, Mateja Štefančič, Katarina Šter, Vesna Zalar Serjun, Māris Šinka, Alise Sapata, Genādijs Šahmenko, Evaldas Šerelis, Baiba Migliniece, and Lidija Korat Bensa

Subjects
digital concrete, 3D printing, oil shale ash, supplementary cementitious material, collision milling, Technology
Abstract

Concrete is an essential construction material, and infrastructures, such as bridges, tunnels, and power plants, consume large quantities of it. Future infrastructure demands and sustainability issues necessitate the adoption of non-conventional supplementary cementitious materials (SCMs). At the same time, global labor shortages are compelling the conservative construction sector to implement autonomous and digital fabrication methods, such as 3D printing. This paper thus investigates the feasibility of using oil shale ash (OSA) as an SCM in concrete suitable for 3D printing, and collision milling is examined as a possible ash pretreatment. OSA from four different sources was collected and analyzed for its physical, chemical, and mineralogical composition. Concrete formulations containing ash were tested for mechanical performance, and the two best-performing formulations were assessed for printability. It was found that ash extracted from flue gases by the novel integrated desulfurizer has the greatest potential as an SCM due to globular particles that contain β-calcium silicate. The 56-day compression strength of concrete containing this type of ash is ~60 MPa, the same as in the reference composition. Overall, collision milling is effective in reducing the size of particles larger than 10 μm but does not seem beneficial for ash extracted from flue gasses. However, milling bottom ash may unlock its potential as an SCM, with the optimal milling frequency being ~100 Hz.

Published
2025
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21. The truncated moment problem on the union of parallel lines

Author

Zalar, Aljaž

Subjects
Mathematics - Functional Analysis, Primary 44A60, 47A57, 47A20, Secondary 15A04, 47N40
Abstract

In this article we study the bivariate truncated moment problem (TMP) of degree $2k$ on the union of parallel lines. First we present an alternative proof of Fialkow's solution \cite{Fia15} to the TMP on the union of two parallel lines (TMP--2pl) using the solution of the truncated Hamburger moment problem (THMP). We add a new equivalent solvability condition, which is then used together with the THMP, to solve the TMP on the union of three parallel lines (TMP--3pl), our second main result of the article. Finally, we establish a sufficient condition for the existence of a solution to the TMP on the union of $n$ parallel lines in the pure case, i.e.\ when the moment matrix $M_k$ is of the highest possible rank, or equivalently the only column relations come from the union of $n$ lines. The condition is based on the feasibility of a certain linear matrix inequality, corresponding to the extension of $M_k$ by adding rows and columns indexed by some monomials of degree $k+1$. The proof is by induction on $n$, where $n\geq 2$ and for the base of induction $n=2$ we use the solution of the TMP--2pl., Comment: 44 pages; To appear in Linear Algebra and Its Applications

Published
2021
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22. The strong truncated Hamburger moment problem with and without gaps

Author

Zalar, Aljaž

Subjects
Mathematics - Functional Analysis, Primary 47A57, 47A20, 44A60, Secondary 15A04, 47N40
Abstract

The strong truncated Hamburger moment problem (STHMP) of degree $(-2k_1,2k_2)$ asks to find necessary and sufficient conditions for the existence of a positive Borel measure, supported on $\mathbb{R}\setminus \{0\}$, such that $\beta_i=\int x^id\mu\; (-2k_1\leq i\leq 2k_2)$. Using the solution of the truncated Hamburger moment problem and the properties of Hankel matrices we solve the STHMP. Then, using the equivalence with the STHMP of degree $(-2k,2k)$, we obtain the solution of the 2-dimensional truncated moment problem (TMP) of degree $2k$ with variety $xy=1$, first solved by Curto and Fialkow. Our addition to their result is the fact previously known only for $k=2$, that the existence of a measure is equivalent to the existence of a flat extension of the moment matrix. Further on, we solve the STHMP of degree $(-2k_1,2k_2)$ with one missing moment in the sequence, i.e., $\beta_{-2k_1+1}$ or $\beta_{2k_2-1}$, which also gives the solution of the TMP with variety $x^2y=1$ as a special case, first studied by Fialkow., Comment: 20 pages. arXiv admin note: text overlap with arXiv:2007.11846

Published
2021
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25. Tunability of the elastocaloric response in main-chain liquid crystalline elastomers

Author

Lavrič, M., Derets, N., Črešnar, D., Cresta, V., Domenici, V., Rešetič, A., Skačej, G., Sluban, M., Umek, P., Zalar, B., Kutnjak, Z., and Rožič, B.

Subjects
Condensed Matter - Soft Condensed Matter
Abstract

Materials exhibiting a large caloric effect could lead to the development of new generation of heat-management technologies that will have better energy efficiency and be potentially more environmentally friendly. The focus of caloric materials investigations has shifted recently from solid-state materials toward soft materials, such as liquid crystals and liquid crystalline elastomers. It has been shown recently that a large electrocaloric effect exceeding 7 K can be observed in smectic liquid crystals. Here, we report on a significant elastocaloric response observed by direct elastocaloric measurements in main-chain liquid crystal elastomers. It is demonstrated that the character of the nematic to paranematic/isotropic transition can be tuned from the supercritical regime towards the first-order regime, by decreasing the density of crosslinkers. In the latter case, the latent heat additionally enhances the elastocaloric response. Our results indicate that a significant elastocaloric response is present in main-chain liquid crystalline elastomers, driven by stress fields much smaller than in solid elastocaloric materials. Therefore, elastocaloric soft materials can potentially play a significant role as active cooling/heating elements in the development of new heat-management devices.

Published
2020
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26. The truncated Hamburger moment problems with gaps in the index set

Author

Zalar, Aljaž

Subjects
Mathematics - Functional Analysis, Primary 47A57, 47A20, 44A60, Secondary 15A04, 47N40
Abstract

In this article we solve four special cases of the truncated Hamburger moment problem (THMP) of degree $2k$ with one or two missing moments in the sequence. As corollaries we obtain, by using appropriate substitutions, the solutions to bivariate truncated moment problems of degree $2k$ for special curves. Namely, for the curves $y=x^3$ (first solved by Fialkow), $y^2=x^3$, $y=x^4$ where a certain moment of degree $2k+1$ is known and $y^3=x^4$ with a certain moment given. The main technique is the completion of the partial positive semidefinite matrix (ppsd) such that the conditions of Curto and Fialkow's solution of the THMP are satisfied. The main tools are the use of the properties of positive semidefinite Hankel matrices and a result on all completions of a ppsd matrix with one unknown entry, proved by the use of the Schur complements for $2\times 2$ and $3\times 3$ block matrices., Comment: 32 pages

Published
2020
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29. Microbial Diversity of Biodeteriorated Limestone Cultural Heritage Assets Identified Using Molecular Approaches—A Literature Review

Author

Hana Suchy, Polona Zalar, and Maria Filomena Macedo

Subjects
limestone monuments, limestone buildings, algae, archaea, bacteria, cyanobacteria, Technology, Engineering (General). Civil engineering (General), TA1-2040, Biology (General), QH301-705.5, Physics, QC1-999, Chemistry, QD1-999
Abstract

A significant part of our stone heritage is made of limestone. Researchers are increasingly concerned about the risk of biodeterioration of these important objects. In this article, we present an up-to-date review of the microbial diversity of biodeteriorated limestone cultural heritage (CHL). This is based on an extensive bibliographic search of the literature investigating biodiversity using culture-dependent (CD) and culture-independent (CI) techniques. In the case of the former, only articles in which microorganisms were identified using molecular tools that generate DNA sequences were selected, with the aim of providing traceable identification based on the sequences submitted to public databases. The literature search resulted in the selection of 50 articles published between 2004 and 2023. The biodiversity data obtained from the CHL were organized into the following groups: fungi (626 records), bacteria and cyanobacteria (786 and 103 records, respectively), algae (51 records), and archaea (27 records). Within each group, the microbial diversity studied was compared according to results obtained using CD and CI techniques. Of all the articles selected, 12 used both approaches, demonstrating the growing effort to discover the total microbiome of biodeteriorated cultural heritage assets.

Published
2024
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30. The Tracial Moment Problem on Quadratic Varieties

Author

Bhardwaj, Abhishek and Zalar, Aljaz

Subjects
Mathematics - Functional Analysis, 47A57, 15A45, 13J30 (Primary), 11E25, 44A60, 15-04 (Secondary)
Abstract

The truncated moment problem asks to characterize finite sequences of real numbers that are the moments of a positive Borel measure on Rn. Its tracial analog is obtained by integrating traces of symmetric matrices and is the main topic of this article. The solution of the bivariate quartic tracial moment problem with a nonsingular (7x7) moment matrix M(2) whose columns are indexed by words of degree 2 was established by Burgdorf and Klep, while in our previos work we completely solved all cases with M(2) of rank at most 5, split M(2) of rank 6 into four possible cases according to the column relation satisfied and solved two of them. Our first main result in this article is the solution for M(2) satisfying the third possible column relation, i.e., Y^2 = 1 + X^2. Namely, the existence of a representing measure is equivalent to the feasibility problem of certain linear matrix inequalities. The second main result is a thorough analysis of the atoms in the measure for M(2) satisfying Y^2 = 1, the most demanding column relation. We prove that size 3 atoms are not needed in the representing measure, a fact proved to be true in all other cases. The third main result extends the solution for M(2) of rank 5 to general M(n), n>1, with two quadratic column relations. The main technique is the reduction of the problem to the classical univariate truncated moment problem, an approach which applies also in the classical truncated moment problem. Finally, our last main result, which demonstrates this approach, is a simplification of the proof for the solution of the degenerate truncated hyperbolic moment problem first obtained by Curto and Fialkow., Comment: 25 pages, 2 appendices

Published
2020

32. A local-global principle for linear dependence in enveloping algebras of Lie algebras

Author

Cimprič, Jaka and Zalar, Aljaž

Subjects
Mathematics - Representation Theory, Mathematics - Rings and Algebras, 16W10, 17B10
Abstract

For every associative algebra $A$ and every class $\mathcal{C}$ of representations of $A$ the following question (related to nullstellensatz) makes sense: Characterize all tuples of elements $a_1,\ldots,a_n \in A$ such that vectors $\pi(a_1)v,\ldots,\pi(a_n)v$ are linearly dependent for every $\pi \in \mathcal{C}$ and every $v$ from the representation space of $\pi$. We answer this question in the following cases: (1) $A=U(L)$ is the enveloping algebra of a finite-dimensional complex Lie algebra $L$ and $\mathbb{C}$ is the class of all finite-dimensional representations of $A$. (2) $A=U(\mathfrak{sl}_2(\mathbb{C}))$ and $\mathbb{C}$ is the class of all finite-dimensional irreducible representations of $A$. (3) $A=U(\mathfrak{sl}_3(\mathbb{C}))$ and $\mathbb{C}$ is the class of all finite-dimensional irreducible representations of $A$ with sufficiently high weights. In case (1) the answer is: tuples that are linearly dependent over $\mathbb{C}$ while in cases (2) and (3) the answer is: tuples that are linearly dependent over the center of $A$. Similar results have been proved before for free algebras and Weyl algebras., Comment: 21 pages

Published
2019

34. Shed Light in the DaRk LineagES of the Fungal Tree of Life-STRES.

Author

Selbmann, Laura, Benkő, Zsigmond, Coleine, Claudia, de Hoog, Sybren, Donati, Claudio, Druzhinina, Irina, Emri, Tamás, Ettinger, Cassie L, Gladfelter, Amy S, Gorbushina, Anna A, Grigoriev, Igor V, Grube, Martin, Gunde-Cimerman, Nina, Karányi, Zsolt Ákos, Kocsis, Beatrix, Kubressoian, Tania, Miklós, Ida, Miskei, Márton, Muggia, Lucia, Northen, Trent, Novak-Babič, Monika, Pennacchio, Christa, Pfliegler, Walter P, Pòcsi, Istvàn, Prigione, Valeria, Riquelme, Meritxell, Segata, Nicola, Schumacher, Julia, Shelest, Ekaterina, Sterflinger, Katja, Tesei, Donatella, U'Ren, Jana M, Varese, Giovanna C, Vázquez-Campos, Xabier, Vicente, Vania A, Souza, Emanuel M, Zalar, Polona, Walker, Allison K, and Stajich, Jason E

Subjects
Dothideomycetes, Eurotiomycetes, adaptation, black fungi, extremophiles, genomics, metabolomics, secondary metabolites, stress conditions, transcriptomics
Abstract

The polyphyletic group of black fungi within the Ascomycota (Arthoniomycetes, Dothideomycetes, and Eurotiomycetes) is ubiquitous in natural and anthropogenic habitats. Partly because of their dark, melanin-based pigmentation, black fungi are resistant to stresses including UV- and ionizing-radiation, heat and desiccation, toxic metals, and organic pollutants. Consequently, they are amongst the most stunning extremophiles and poly-extreme-tolerant organisms on Earth. Even though ca. 60 black fungal genomes have been sequenced to date, [mostly in the family Herpotrichiellaceae (Eurotiomycetes)], the class Dothideomycetes that hosts the largest majority of extremophiles has only been sparsely sampled. By sequencing up to 92 species that will become reference genomes, the "Shed light in The daRk lineagES of the fungal tree of life" (STRES) project will cover a broad collection of black fungal diversity spread throughout the Fungal Tree of Life. Interestingly, the STRES project will focus on mostly unsampled genera that display different ecologies and life-styles (e.g., ant- and lichen-associated fungi, rock-inhabiting fungi, etc.). With a resequencing strategy of 10- to 15-fold depth coverage of up to ~550 strains, numerous new reference genomes will be established. To identify metabolites and functional processes, these new genomic resources will be enriched with metabolomics analyses coupled with transcriptomics experiments on selected species under various stress conditions (salinity, dryness, UV radiation, oligotrophy). The data acquired will serve as a reference and foundation for establishing an encyclopedic database for fungal metagenomics as well as the biology, evolution, and ecology of the fungi in extreme environments.

Published
2020

36. Experimental characterisation of protein-protein and protein-excipient interactions and their impact on protein conformation and aggregation

Author

Zalar, Matja, Warwicker, James, and Golovanov, Alexander

Subjects
protein formulation, monoclonal antibodies, NMR, biopharmaceutical proteins, protein-excipient interactions, protein-protein interactions, scaffold proteins
Abstract

In the last decades, biopharmaceutical proteins, especially monoclonal antibodies (mAbs), have become one of the fastest growing classes of pharmaceuticals, due to their high affinity, specificity, non-toxicity, and low immunogenicity. Despite their versatility and wide applicability, their production is costly and poses unique challenges due to their high molecular weight and structural complexity. One of the major challenges in formulation development is thus prevention of protein self-association that may lead into formation of potentially immunogenic aggregates. To achieve this, excipients are often added in relatively high concentrations to the final formulations. However, there is a lack of information available on the impact of co-solutes, including excipients on protein stability. In light of these inherent problems of mAbs, alternative systems, such as protein aptamers, have been developed for high affinity binders for specific targets. Some advantages of peptide aptamers are their smaller size, versatility, specificity for chosen targets, and ease of production. However, the insertion of binding loops may cause destabilisation of protein, leading to formation of inactive oligomeric species. In the first part of the Thesis we have used a stefin A derived scaffold protein, SQT, as a model to study solution behaviour and self-association of such systems. We have determined its crystal structure, and investigated possible pathways of oligomer formation. We studied the oligomerisation kinetics and determined the limiting steps of dimer and tetramer formation. Using mutagenesis, we created a more stable variant of the SQT scaffold. In the second part of this Thesis we have applied solution NMR spectroscopy to comprehensively evaluate protein-excipient interactions between seven biotherapeutically relevant proteins and a set of eleven commonly used excipients. Additionally, we evaluated the effect of excipients on thermal and colloidal protein stability, the aggregation kinetics at elevated temperatures and on the protein storage stability at accelerated conditions. In the last part of the Thesis we have combined both protein and ligand-observed NMR approaches to evaluate interactions between the stabilised SQT variant and various excipients. We used isotopically labelled protein to evaluate the potential interaction sites on the protein surface and estimated the binding constants for individual excipients. Furthermore, we compared the sensitivity of both protein- and ligand-observed methods and discussed how they could be applied to biopharmaceutical formulations.

Published
2020

37. Xerophilic fungi contaminating historically valuable easel paintings from Slovenia

Author

Polona Zalar, Daša Graf Hriberšek, Cene Gostinčar, Martin Breskvar, Sašo Džeroski, Mojca Matul, Monika Novak Babič, Jerneja Čremožnik Zupančič, Amela Kujović, Nina Gunde-Cimerman, and Katja Kavkler

Subjects
fungi, easel paintings, contamination, damage, machine learning, biodeterioration, Microbiology, QR1-502
Abstract

Historically valuable canvas paintings are often exposed to conditions enabling microbial deterioration. Painting materials, mainly of organic origin, in combination with high humidity and other environmental conditions, favor microbial metabolism and growth. These preconditions are often present during exhibitions or storage in old buildings, such as churches and castles, and also in museum storage depositories. The accumulated dust serves as an inoculum for both indoor and outdoor fungi. In our study, we present the results on cultivable fungi isolated from 24 canvas paintings, mainly exhibited in Slovenian sacral buildings, dating from the 16th to 21st centuries. Fungi were isolated from the front and back of damaged and undamaged surfaces of the paintings using culture media with high- and low-water activity. A total of 465 isolates were identified using current taxonomic DNA markers and assigned to 37 genera and 98 species. The most abundant genus was Aspergillus, represented by 32 species, of which 9 xerophilic species are for the first time mentioned in contaminated paintings. In addition to the most abundant xerophilic A. vitricola, A. destruens, A. tardicrescens, and A. magnivesiculatus, xerophilic Wallemia muriae and W. canadensis, xerotolerant Penicillium chrysogenum, P. brevicompactum, P. corylophilum, and xerotolerant Cladosporium species were most frequent. When machine learning methods were used to predict the relationship between fungal contamination, damage to the painting, and the type of material present, proteins were identified as one of the most important factors and cracked paint was identified as a hotspot for fungal growth. Aspergillus species colonize paintings regardless of materials, while Wallemia spp. can be associated with animal fat. Culture media with low-water activity are suggested in such inventories to isolate and obtain an overview of fungi that are actively contaminating paintings stored indoors at low relative humidity.

Published
2023
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41. Engineering the Comfort‐of‐Wear for Next Generation Wearables

Author

Tokihiko Shimura, Shun Sato, Peter Zalar, and Naoji Matsuhisa

Subjects
flexible electronics, smart healthcare sensors, stretchable electronics, wearable electronics, wearables, Electric apparatus and materials. Electric circuits. Electric networks, TK452-454.4, Physics, QC1-999
Abstract

Abstract Wearable technologies are becoming important for the fields of information technology and healthcare, driven mainly by societal issues such as the aging society and the current pandemic. Recently developed flexible/stretchable wearable devices have demonstrated their ability for long‐term healthcare monitoring with improved signal integrity and multimodality. However, the adherence of wearers to such wearable devices cannot be determined only by the function. Here “comfort‐of‐wear” is identified as one of the most critical parameters for future wearables, similar to how clothes are chosen based on how comfortable they are. “Comfort‐of‐wear” is defined as the device's ability to not to disturb the wearers’ daily life. Several engineering approaches are introduced to improve the comfort‐of‐wear of devices—via strategies that include improving flexibility by utilizing a combination of structures, materials, and systems. Finally, the future of wearables enabled by cutting‐edge advanced electronic technologies is proposed.

Published
2023
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44. Collision Milling of Oil Shale Ash as Constituent Pretreatment in Concrete 3D Printing.

Author

Hanžič, Lucija, Štefančič, Mateja, Šter, Katarina, Zalar Serjun, Vesna, Šinka, Māris, Sapata, Alise, Šahmenko, Genādijs, Šerelis, Evaldas, Migliniece, Baiba, and Korat Bensa, Lidija

Subjects
RAPID prototyping, OIL shales, SHALE oils, FLUE gases, THREE-dimensional printing
Abstract

Concrete is an essential construction material, and infrastructures, such as bridges, tunnels, and power plants, consume large quantities of it. Future infrastructure demands and sustainability issues necessitate the adoption of non-conventional supplementary cementitious materials (SCMs). At the same time, global labor shortages are compelling the conservative construction sector to implement autonomous and digital fabrication methods, such as 3D printing. This paper thus investigates the feasibility of using oil shale ash (OSA) as an SCM in concrete suitable for 3D printing, and collision milling is examined as a possible ash pretreatment. OSA from four different sources was collected and analyzed for its physical, chemical, and mineralogical composition. Concrete formulations containing ash were tested for mechanical performance, and the two best-performing formulations were assessed for printability. It was found that ash extracted from flue gases by the novel integrated desulfurizer has the greatest potential as an SCM due to globular particles that contain β-calcium silicate. The 56-day compression strength of concrete containing this type of ash is ~60 MPa, the same as in the reference composition. Overall, collision milling is effective in reducing the size of particles larger than 10 μm but does not seem beneficial for ash extracted from flue gasses. However, milling bottom ash may unlock its potential as an SCM, with the optimal milling frequency being ~100 Hz. [ABSTRACT FROM AUTHOR]

Published
2025
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45. Degradation Potential of Xerophilic and Xerotolerant Fungi Contaminating Historic Canvas Paintings

Author

Amela Kujović, Cene Gostinčar, Katja Kavkler, Natalija Govedić, Nina Gunde-Cimerman, and Polona Zalar

Subjects
enzymes, biodeterioration, moulds, oil paintings, Aspergillus, Penicillium, Biology (General), QH301-705.5
Abstract

Fungi are important contaminants of historic canvas paintings worldwide. They can grow on both sides of the canvas and decompose various components of the paintings. They excrete pigments and acids that change the visual appearance of the paintings and weaken their structure, leading to flaking and cracking. With the aim of recognizing the most dangerous fungal species to the integrity and stability of paintings, we studied 55 recently isolated and identified strains from historic paintings or depositories, including 46 species from 16 genera. The fungi were categorized as xero/halotolerant or xero/halophilic based on their preference for solutes (glycerol or NaCl) that lower the water activity (aw) of the medium. Accordingly, the aw value of all further test media had to be adjusted to allow the growth of xero/halophilic species. The isolates were tested for growth at 15, 24 °C and 37 °C. The biodeterioration potential of the fungi was evaluated by screening their acidification properties, their ability to excrete pigments and their enzymatic activities, which were selected based on the available nutrients in paintings on canvas. A DNase test was performed to determine whether the selected fungi could utilize DNA of dead microbial cells that may be covering surfaces of the painting. The sequestration of Fe, which is made available through the production of siderophores, was also tested. The ability to degrade aromatic and aliphatic substrates was investigated to consider the potential degradation of synthetic restoration materials. Xerotolerant and moderately xerophilic species showed a broader spectrum of enzymatic activities than obligate xerophilic species: urease, β-glucosidase, and esterase predominated, while obligate xerophiles mostly exhibited β-glucosidase, DNase, and urease activity. Xerotolerant and moderately xerophilic species with the highest degradation potential belong to the genus Penicillium, while Aspergillus penicillioides and A. salinicola represent obligately xerophilic species with the most diverse degradation potential in low aw environments.

Published
2024
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46. Thermomechanical response of liquid crystal elastomers: role of crosslinker density

Author

N Derets, V Domenici, A Rešetič, and B Zalar

Subjects
thermomechanical response, liquid crystal elastomers, composites, Materials of engineering and construction. Mechanics of materials, TA401-492, Chemical technology, TP1-1185
Abstract

In this work thermomechanical properties of main-chain liquid crystal elastomers (MC-LCEs) with different degrees of crosslinking were investigated, and gradual loss of thermomechanical response was observed on repetitive measurements. Specifically, six samples of MC-LCEs were prepared, with crosslinker-to-mesogen relative concentration ranging from 5% to 10% in steps of 1%. The obtained results were then compared to thermomechanical response of side-chain liquid crystal elastomers (SC-LCEs). Additionally, thermomechanical response of polymer dispersed main-chain liquid crystal elastomers (MC-PDLCEs) was investigated. Results indicate that in MC-LCEs the concentration of crosslinker defines thermomechanical response and affects stability of the system. The loss of thermomechanical response is negligible in the case of crosslinker to mesogen ratio being the smallest, namely in 5% sample, and it is unaffected by glasslike to nematic phase transition. SC-LCEs do not show any sign of such behaviour and remain stable after several cycles of thermomechanical measurements.

Published
2024
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48. Genomic evidence for intraspecific hybridization in a clonal and extremely halotolerant yeast

Author

Gostinčar, Cene, Stajich, Jason E, Zupančič, Jerneja, Zalar, Polona, and Gunde-Cimerman, Nina

Subjects
Microbiology, Biological Sciences, Genetics, Biotechnology, Human Genome, Ascomycota, Diploidy, Ecosystem, Genome, Fungal, Genomics, Hybridization, Genetic, Phylogeny, Whole genome duplication, Hybridization, Clonal reproduction, Restricted recombination, Halotolerance, Polyextremotolerance, Salt stress, Black yeast, Ploidy, Information and Computing Sciences, Medical and Health Sciences, Bioinformatics, Biological sciences, Biomedical and clinical sciences
Abstract

BackgroundThe black yeast Hortaea werneckii (Dothideomycetes, Ascomycota) is one of the most extremely halotolerant fungi, capable of growth at NaCl concentrations close to saturation. Although dothideomycetous fungi are typically haploid, the reference H. werneckii strain has a diploid genome consisting of two subgenomes with a high level of heterozygosity.ResultsIn order to explain the origin of the H. werneckii diploid genome we here report the genome sequencing of eleven strains isolated from different habitats and geographic locations. Comparison of nine diploid and two haploid strains showed that the reference genome was likely formed by hybridization between two haploids and not by endoreduplication as suggested previously. Results also support additional hybridization events in the evolutionary history of investigated strains, however exchange of genetic material in the species otherwise appears to be rare. Possible links between such unusual reproduction and the extremotolerance of H. werneckii remain to be investigated.ConclusionsH. werneckii appears to be able to form persistent haploid as well as diploid strains, is capable of occasional hybridization between relatively heterozygous haploids, but is otherwise limited to clonal reproduction. The reported data and the first identification of haploid H. werneckii strains establish this species as a good model for studying the effects of ploidy and hybridization in an extremotolerant system unperturbed by frequent genetic recombination.

Published
2018

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