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Pnicturesque Luminescence : The Photophysical and Emissive Properties of Dipyridine Pyrrolide Group 15 Diiodide Complexes
No full textThe synthesis, characterization, and photophysical properties of a family of pnictogen complexes Pn(DPP)I2 bearing dipyridine pyrrolide (DPP−) ligands and with As, Sb, and Bi as the central atom Pn are reported. Slight but systematic trends arising from the variation in the atomic number are apparent in NMR and UV–vis spectra. As confirmed by time‐dependent density functional theory calculations, the electron‐rich DPP− ligand endows the energetically lowest‐lying electronic absorption band with partial DPP‐to‐Pn charge–transfer (ligand‐to‐metal charge transfer) character. All complexes are phosphorescent at cryogenic temperatures with high phosphorescence quantum yields of Φphos = 50.8 to 83.9% and lifetimes in the range of tens of microseconds. In accordance with the heavy atom effect, merely As(DPP)I2, the lightest representative of the three complexes within this work, displays weak fluorescence. It also possesses the shortest phosphorescence lifetime and the highest quantum yield for 1O2 generation. This is attributed to a higher degree of covalent character of the Pn‐ligand bonds and increased orbital overlap as well as larger iodide contributions to the LUMO.publishe
The effect of music listening style on music-induced analgesia
No full textMusic listening may decrease pain via psychobiological mechanisms. Music listening style (MLS) influences music processing: Music empathizers (ME) focus on emotional aspects of music, whereas music systemizers (MS) focus on structural aspects, potentially affecting processes of music-induced analgesia. The effects of the MLS on music-induced analgesia might depend on the source of music selection (i.e. who selects the music) and gender. Different psychological mechanisms, such as stimulus-induced emotions and subjective stress, might mediate the effects of an empathizing versus systemizing MLS on pain. The purpose of this study was (a) to test how MLS influences pain during music listening, depending on the source of music selection and gender, and (b) to explore underlying psychological mechanisms. 61 participants (age: M = 24.23, SD = 3.85; four groups: male/female ME/MS) listened to stimuli (participant-selected/researcher-selected music/control) during cold pressor tests. Pain intensity, pain tolerance, and psychological mechanisms (stimulus-induced emotions, subjective stress) were repeatedly measured. Multilevel and mediation analyses were conducted. The MLS did not directly influence pain, but female ME were most pain sensitive with participant-selected music. Pain was tolerated longest for participant-selected music. The effect of MLS on pain intensity was not mediated by stimulus-induced emotions but by subjective stress. Our results indicate that music increases pain tolerance the most when participants select it. However, we found initial evidence that women scoring high on ME show increased pain when listening to their self-selected music. We also found initial evidence for the importance of subjective stress as a potential mechanism in the context of music-based pain management.publishe
Matrices having a positive determinant and all other minors nonpositive
No full textThe class of square matrices of order having a positive determinant and all their minors up to order −1 nonpositive is considered. A characterization of these matrices based on the Cauchon algorithm is presented, which provides an easy test for their recognition. Furthermore, it is shown that all matrices lying between two matrices of this class with respect to the checkerboard ordering are contained in this class, too. For both results, we require that the entry in the bottom-right position is negative.publishe
A Method for Establishing Asymptotically Accurate Bounds for Extreme Roots of Eulerian Polynomials Using Polynomial Stability Preservers
No full textWe develop tools to study, understand and bound extreme roots of multivariate real zero polynomials globally. This is done through the use of a relaxation that approximates their rigidly convex sets. This relaxation can easily be constructed using the degree truncation of the polynomial and it produces in this way a spectrahedron whose computation is relatively easy and whose size is relatively small and depending solely on the number of variables of the polynomial. As we know that, in order to be able to produce in general spectrahedral representations of rigidly convex sets, it is necessary to build matrices of very big size, we try, analyze and experiment with several constructions that could increase the size of the matrices of the relaxation. We develop tools to study, understand and bound extreme roots of multivariate real zero polynomials globally. This is done through the use of a relaxation that approximates their rigidly convex sets. This relaxation can easily be constructed using the degree truncation of the polynomial and it produces in this way a spectrahedron whose computation is relatively easy and whose size is relatively small and depending solely on the number of variables of the polynomial. As we know that, in order to be able to produce in general spectrahedral representations of rigidly convex sets, it is necessary to build matrices of very big size, we try, analyze and experiment with several constructions that could increase the size of the matrices of the relaxation. These constructions are based principally in two main approaches: adding information about higher degree monomials or non-trivially increasing the number of variables of the original polynomial. We explore these two construction first in a general setting and see that it is necessary to particularize to certain families of polynomials in order to make them work. In particular, we are able to prove that increasing the number of variables improves the behavior of the relaxation along the diagonal in the case of Eulerian polynomials. We see that applying the relaxation to multivariate Eulerian polynomials and then looking at the univariate polynomials injected in their diagonals produces an exponential asymptotic improvement in the bounds provided. We compare these bounds with other bounds that have appeared previously in the literature and refine these previous bounds in order to study how close do the bounds provided by the relaxation are to the actual roots of the Eulerian polynomials. As the univariate Eulerian polynomials present symmetries that helped us to understand better the structure of their roots, we also study generalizations of these notions of symmetry to multivariate Eulerian polynomials. These generalizations of symmetry shed new light on the combinatorial object these polynomials encode. Finally, the combination of all these techniques coming from real algebraic geometry, the theory of stability preservers, the numerical methods for root estimations and the study of symmetries of polynomials encoding combinatorial objects that we use in this thesis along the path suggested by Eulerian polynomials suggests to us that there is much more happening under the surface. This additional knowledge would affect and increase our understanding of many more families of polynomials emerging as generating polynomials associated to combinatorial objects, this is, in the same way as Eulerian polynomials emerge. Thus, the insights provided here by the study of Eulerian polynomials allow us to propose a further reaching mathematical program aimed at studying and delving deeper into the relations, connections and phenomena first devised and exemplified by the work presented here on Eulerian polynomials. We name this program the Mindelsee Program and find that it encourages connecting paths that could open bridges between many different areas of mathematics promoting thus the study of new families of (mainly real zero) polynomials and of new techniques aimed at improving our abilities to perform the task of understanding better the overall structure of their roots in depth.publishe
A Simple Explanation for Harmonic Word Order
No full textHarmonic word order is a well-established tendency in natural languages, which has previously been explained as a single ordering rule for all head-dependent relations. We propose that it can be more parsimoniously explained as an outcome of word-class frequencies, where the purported “head” is the most frequently instantiated word class in a phrasal schema. We show that the most frequent class gravitates spontaneously to an edge position in a phrasal replication process, as long as words of one class may influence the position of words of another class. This avoids the need to posit head-dependent ordering as an innate rule or bias, simplifying our theory of word order. We demonstrate the spontaneous emergence of harmony from word-class frequencies using a simple computational model of phrasal replication, and in further extensions show that the principle remains robust with fuzzy word classes and multiword chunks, can capture competition between harmony and locality, and is compatible with the results of behavioral experiments on harmonic ordering. Our findings support further exploration of syntactic models with nondiscrete word classes.publishe
Diversity and productivity of a natural grassland decline with the number of global change factors
No full textGrasslands are highly diverse ecosystems providing important ecosystem services, but they currently face a variety of anthropogenic stressors simultaneously. Quantifying grassland responses to global change factors (GCFs) is crucial for developing effective strategies to mitigate the negative impacts of global change on grassland communities and to promote their resilience in the face of future environmental challenges. We conducted a field experiment in the Songnen grassland, northeastern China, to test the combined effects of 0, 1, 2, 4, 6 and 8 GCFs, including fungicide, herbicide, insecticide, antibiotic stress, heavy metal pollution, light pollution, microplastic pollution, nitrogen deposition, tillage disturbance and increased precipitation. We found that within one year, the increasing number of GCFs negatively impacts both the productivity and diversity of grassland communities. In comparison to exposure to a single GCF, exposure to 8 GCFs led to a reduction in productivity and species richness by 42.8% and 42.9%, respectively. Furthermore, these negative effects seem to be linked to the reduction of dominant species and the concurrent increase in neonative species (i.e., species that have expanded their geographic range into a new area without direct human assistance, but as an indirect consequence of human-induced environmental changes). The results of hierarchical diversity-interaction modeling suggested that the adverse impacts of an increasing number of GCFs on community productivity and diversity are attributable to both the specific identities of GCFs involved and their unique pairwise interactions. The results suggest that grasslands may quickly lose stability and degrade more rapidly in response to multiple co-occurring GCFs. Greater efforts should be made to conserve the functions and services of grassland ecosystems by reducing the impacts of human activities.publishe
Research Data Management Practices Across the Research Data Lifecycle and Their Potential for Collaboration in an International Higher Education Alliance
No full textProper research data management facilitates collaboration and promotes research progress through the synergetic process of publishing and reusing research data. Despite these advantages, extant literature reveals that researchers often struggle to manage their research data. In this article, we investigate the relation between research data management practices and collaboration in a context that was made to spark or intensify collaboration—a European Universities alliance. We conducted 39 semi-structured interviews addressing the whole research data lifecycle predominantly with researchers, but also support staff, from six universities that were or were shortly to become part of a European Universities alliance. Our findings show that researchers’ practices affect their collaboration in various ways. For example, we find that sharing data within research teams constitutes an obstacle to collaboration due to international differences and technical impediments. Publishing data openly is also associated with certain reservations, such as a lack of knowledge. Furthermore, doubts toward existing data hinder researchers from reusing other researchers’ data. International higher education alliances such as European Universities alliance should keep these impediments in mind and offer solutions which foster collaboration.publishe
Kontaktstudium Informatik : ein Strukturmodell für die hochschulverortete berufsbegleitende Lehrkräftenachqualifizierung
No full textDie Einbindung von Hochschulen in berufsbegleitende, wissenschaftliche Weiterbildungsangebote für Lehrkräfte und insbesondere deren Systematisierung befindet sich in Deutschland noch im Aufbau. Das wissenschaftlich begleitete fachwissenschaftliche Nachqualifizierungsprogramm „Kontaktstudium Informatik“ der Universität Konstanz hat seit 2018 über 1.000 Lehrkräfte in Baden-Württemberg berufsbegleitend nachqualifiziert. Als prototypisches Strukturmodell zeichnet es sich durch seine Verankerung im Landeshochschulgesetz, eine Bologna-Kompatibilität, die Integration in die Qualitätssicherung der Universität Konstanz, die Implementierung als Microcredential mit Abschlusszertifikat und ein institutionell übergreifendes kooperatives Governance-Modell aus.publishe
Scattering approach to near-field radiative heat transfer
No full textWe formulate the problem of near-field radiative heat transfer as an effective quantum scattering theory for excitations of the matter. Built from the same ingredients as the semiclassical fluctuational electrodynamics, the standard tool to handle this problem, our construction makes manifest its relation to the Landauer-Büttiker scattering framework, which appears only implicitly in the fluctuational electrodynamics. We show how to construct the scattering matrix for the matter excitations and give a general expression for the energy current in terms of this scattering matrix. We show that the energy current has an important nondissipative contribution that can dominate the finite-frequency noise while being absent in the average current. Our construction provides a unified description of near-field radiative heat transfer in diverse physical systems.publishe