Flora of the tram tracks of Bratislava

Urban Ecosystems - Tram and railway tracks represent specific urban habitats, which host a specific type of flora. This study aims to compile the information about species composition of flora of...     

More Money,More Problems? Resource Dependence and Professionalization of Non-governmental Social Services Organizations in Southern Spain

VOLUNTAS: International Journal of Voluntary and Nonprofit Organizations - This study analyzes the strategies displayed by non-governmental organizations in the social services sector to face the...     

Interdependent Network Recovery Games

Recovery of interdependent infrastructure networks in the presence of catastrophic failure is crucial to the economy and welfare of society. Recently, centralized methods have been developed to address optimal resource allocation in postdisaster recovery scenarios of interdependent infrastructure systems that minimize total cost. In real-world systems, however, multiple independent, possibly noncooperative, utility network controllers are responsible for making recovery decisions, resulting in suboptimal decentralized processes. With the goal of minimizing recovery cost, a best-case decentralized model allows controllers to develop a full recovery plan and negotiate until all parties are satisfied (an equilibrium is reached). Such a model is computationally intensive for planning and negotiating, and time is a crucial resource in postdisaster recovery scenarios. Furthermore, in this work, we prove this best-case decentralized negotiation process could continue indefinitely under certain conditions. Accounting for network controllers' urgency in repairing their system, we propose an ad hoc sequential game-theoretic model of interdependent infrastructure network recovery represented as a discrete time noncooperative game between network controllers that is guaranteed to converge to an equilibrium. We further reduce the computation time needed to find a solution by applying a best-response heuristic and prove bounds on ε-Nash equilibrium, where ε depends on problem inputs. We compare best-case and ad hoc models on an empirical interdependent infrastructure network in the presence of simulated earthquakes to demonstrate the extent of the tradeoff between optimality and computational efficiency. Our method provides a foundation for modeling sociotechnical systems in a way that mirrors restoration processes in practice.     

Minimum Cost Edge Subset Covering Exactly k Vertices of a Graph

Given a graph G with nonnegative edge costs and an integer k, we consider the problem of finding an edge subset S of minimum total cost with respect to the constraint that S covers exactly k vertices of G. An O(n ³) algorithm is presented where n is the order of G. It is based on the author's previous paper dealing with a similar problem asking S to cover at least k vertices.     

Approximation hardness of edge dominating set problems

We provide the first interesting explicit lower bounds on efficient approximability for two closely related optimization problems in graphs, MINIMUM EDGE DOMINATING SET and MINIMUM MAXIMAL MATCHING. We show that it is NP-hard to approximate the solution of both problems to within any constant factor smaller than . The result extends with negligible loss to bounded degree graphs and to everywhere dense graphs. An extended abstract of this paper was accepted at the 14th Annual International Symposium on Algorithms and Computation, ISAAC 2003.     

Beyond Hidden Figures: Shining a Spotlight on Constructed Hierarchies of Gender,Age, and Elementary Mathematics

Gender Issues - This article focuses on conversations about gender and mathematics among other intersecting identities such as age, education level, and professional expertise. I used positioning...     

Understanding the Relationship Between Direct Experience and Risk Perception of Natural Hazards

Risk perception has been largely examined in studies that have aimed to explain and predict preparedness behavior in the context of natural hazards. Findings from studies on the relationship between previous experience, preparedness, and risk perception in disaster situations have been inconsistent. Hence, the main goal of this work was to explore the influence of physical and emotional experience on risk perception regarding natural hazards. This study was conducted in a statistically representative sample of the city of Iquique, in northern Chile (n = 701), who completed a survey one month after the occurrence of an earthquake and tsunami (8.2 Mw). The survey assessed the experience and preparation actions of survivors in relation to this event. Using a structural equation model, we examined nine proposed relationships, six of which were significant. The final model had an adequate fit (χ² = 752.23, df = 283, comparative fit index [CFI] = 0.90, root mean square error of approximation [RMSEA] = 0.049). Direct experience showed the greatest influence on risk perception: while direct physical experience (i.e., the physical and material consequences associated with the earthquake) maintained a direct positive effect on risk perception, direct emotional experience (i.e., the fear of experiencing an earthquake) produced an indirect positive effect (through worry). Emotional experience, however, did not directly influence current preparedness and risk perception. Implications for understanding the relationship between risk perception and direct experience are discussed.     

Subjective Poverty and Its Relation to Objective Poverty Concepts in Hungary

The paper analyzes subjective poverty in Hungary and compares it to the objective poverty concepts. Subjective poverty is defined by examining who people consider to be poor. Based on the Easterlin paradox, the initial hypothesis states that subjective and absolute poverty concepts are highly correlated. Taking into account that Hungary is a developed country, subjective well-being is supposed to be associated not only with absolute, but also with relative deprivation. The methods of systematic data collection are used to collect data about the belief of the population. The paper concludes that low income level, Roma descent, entitlement to social supports and unemployment are the items thought to be most related to poverty by the informants. It proves that subjective poverty is a multidimensional concept. It also concludes that absolute and relative poverty thresholds coincide with the subjective one. It implies that increasing the absolute income level of individuals may not be enough to improve their subjective wellbeing as they are also concerned with their relative income position.     

Testing Parameter Constancy in Stationary Vector Autoregressive Models Against Continuous Change

In this article we derive a parameter constancy test of a stationary vector autoregressive model against the hypothesis that the parameters of the model change smoothly over time. A single structural break is contained in this alternative hypothesis as a special case. The test is a generalization of a single-equation test of a similar hypothesis proposed in the literature. An advantage here is that the asymptotic distribution theory is standard. The performance of the tests is compared to that of generalized Chow-tests and found satisfactory in terms of both size and power.     

Short-Term and Long-Term Effects of Training in EFT: A Multinational Study in Spanish-speaking Countries

This study seeks to validate the cross-cultural effectiveness of emotionally focused couple therapy (EFT) training in a sample of Spanish-speaking clinicians. The 28-hr formalized training for EFT was offered in six different Spanish-speaking countries, covering Europe, North America, Central America, and South America. Two hundred and seven therapists of 14 different Spanish-speaking nationalities completed pre-training assessments, 153 of them completed post-training assessments, and 92 therapists also completed the follow-up assessment. Using multilevel growth modeling (MLM), results indicated that therapists experienced significant and positive changes in terms of EFT competence (knowledge and skill acquisition), mature empathy, self-compassion, and attachment over time. Implications for transnational EFT training, specifically in Spanish-speaking countries, are discussed.