107 research outputs found
Nonlinear dynamic analysis of an optimal particle damper
We study the dynamical behavior of a single degree of freedom mechanical
system with a particle damper. The particle (granular) damping was optimized
for the primary system operating condition by using an appropriate gap size for
a prismatic enclosure. The particles absorb the kinetic energy of the vibrating
structure and convert it into heat through the inelastic collisions and
friction. This results in a highly nonlinear mechanical system. Considering
linear signal analysis, state space reconstruction, Poincar\'e sections and the
determination of maximal Lyapunov exponents, the motion of the granular system
inside the enclosure is characterized for a wide frequency range. With the
excitation frequency as control parameter, either regular and chaotic motion of
the granular bed are found and their influence on the damping is analyzed.Comment: 18 pages, 8 figures. arXiv admin note: text overlap with
arXiv:1105.030
Electrophysiological correlates of the effect of task difficulty on inhibition of return.
Inhibition of return (IOR) refers to slower responses to targets that occur at a previously attended location than to those at control locations. Previous studies on the impact of task difficulty on IOR have shown conflicting results. However, these studies failed to match low-level characteristics of stimuli (e.g., size, color, and luminance) across difficulty levels, and so might have confounded the effect of task difficulty with that of stimulus characteristics. Hence, whether and how task difficulty modulates IOR remain largely unknown. This study utilized the event-related potentials (ERPs) technique in combination with a cue-target paradigm to tackle this question. Task difficulty was manipulated by changing the position of a gap in a rectangle stimulus, while stimulus size, color, and luminance were precisely matched. IOR was observed in reaction times across all difficulty levels but was found in accuracy at the medium level only. The modulation effect of task difficulty on IOR was also evident in the N1 and P2 ERP components, which showed significantly weaker IOR effects at the medium difficulty level than at the easy and hard levels. It is suggested that the modulation of IOR by task difficulty involves both perceptual and post-perceptual processes
Opinion: Why Protect Nature? Rethinking Values and the Environment
A cornerstone of environmental policy is the debate over protecting nature for humans’ sake (instrumental values) or for nature’s (intrinsic values) (1). We propose that focusing only on instrumental or intrinsic values may fail to resonate with views on personal and collective well-being, or “what is right,” with regard to nature and the environment. Without complementary attention to other ways that value is expressed and realized by people, such a focus may inadvertently promote worldviews at odds with fair and desirable futures. It is time to engage seriously with a third class of values, one with diverse roots and current expressions: relational values. By doing so, we reframe the discussion about environmental protection, and open the door to new, potentially more productive policy approaches
Incorporating temporal-bounded CBR techniques in real-time agents
Nowadays, MAS paradigm tries to move Computation to a new level of abstraction: Computation as interaction,
where large complex systems are seen in terms of the services they offer, and consequently in
terms of the entities or agents providing or consuming services. However, MAS technology is found to
be lacking in some critical environments as real-time environments. An interaction-based vision of a
real-time system involves the purchase of a responsibility by any entity or agent for the accomplishment
of a required service under possibly hard or soft temporal conditions. This vision notably increases the
complexity of these kinds of systems. The main problem in the architecture development of agents in
real-time environments is with the deliberation process where it is difficult to integrate complex
bounded deliberative processes for decision-making in a simple and efficient way. According to this, this
work presents a temporal-bounded deliberative case-based behaviour as an anytime solution. More specifically,
the work proposes a new temporal-bounded CBR algorithm which facilitates deliberative processes
for agents in real-time environments, which need both real-time and deliberative capabilities.
The paper presents too an application example for the automated management simulation of internal
and external mail in a department plant. This example has allowed to evaluate the proposal investigating
the performance of the system and the temporal-bounded deliberative case-based behaviour.
2010 Elsevier Ltd. All rights reserved.This work is supported by TIN2006-14630-C03-01 projects of the Spanish government, GVPRE/2008/070 project, FEDER funds and CONSOLIDER-INGENIO 2010 under Grant CSD2007-00022.Navarro Llácer, M.; Heras Barberá, SM.; Julian Inglada, VJ.; Botti Navarro, VJ. (2011). Incorporating temporal-bounded CBR techniques in real-time agents. Expert Systems with Applications. 38(3):2783-2796. https://doi.org/10.1016/j.eswa.2010.08.070S2783279638
Identification of potential source and sink areas for butterflies on the Iberian Peninsula
"This is the peer reviewed version of the following article: Pulido-Pastor, Antonio et al. "Identification of potential source and sink areas for butterflies on the Iberian Peninsula", which has been published in final form at https://doi.org/10.1111/icad.12297. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions."Abstract. 1. The dynamic analysis of geographical distribution is relevant to identify the processes that underlie any changes of geographical ranges. This is an essential element of both biogeography and conservation biology. Fuzzy logic, in particular the fuzzy concept of favourability for species occurrence,
helps to perform a dynamic interpretation of the internal complexity of species ranges.
2. We modelled the distributions of the 222 Iberian butterflies using favourability functions and 92 environmental variables (spatial, climatic, topographic, geological and indicators of human activity). We obtained a significant environmental favourability model for each butterfly.
3. We identified the potential sources and sinks in the distribution area of each butterfly species using their respective favourability and presence–absence maps, considering as sources only those areas with high favourability where the butterfly is present, and sinks only those areas with low favourability where the butterfly is present too.
4. The source areas for the Iberian butterflies are concentrated in the north of the peninsula, mainly in the mountain ranges (Cantabrian Range, Pyrenees and Central Range). Sink areas are more dispersed all around the peninsula. We found a concentration of sink locations in eastern Iberia (Alicante and Murcia provinces) and in the southwestern area (Doñana National Park).
5. This may be helpful when implementing conservation measures, by providing a biogeographical dynamic interpretation of the roles of different parts of the distribution range of the species. Preserving the processes that link sources with sinks is critical for maintaining or improving the sustainability of populationsParts of this work were supported by projects POII11-0277-5747/BANDENCO, CGL2017-86926-P and sDIV (iDIV)WG 4.28 sECUR
Time Course of the Neural Activity Related to Behavioral Decision-Making as Revealed by Event-Related Potentials
Objective: To study the time course of the electrocortical activity evoked by gains and
losses in the Iowa Gambling Task (IGT), the brain sources of this electrical activity, and its
association with behavioral parameters of task performance in order to achieve a better
knowledge of decision-making processes.
Method: Event-related potentials (ERPs) were obtained from a 64-channel EEG in
25 participants when performing the IGT. Brain source localization analyses of the ERP
components were also assessed.
Results: ERP amplitudes were sensitive to gains and losses. An early fronto-central
negativity was elicited when feedback was provided for both gains and losses, and
correlated with the number of gains at FCz and with the number of both gains and
losses at Cz. The P200 component had larger amplitudes to losses and correlated
positively with the number of losses. Feedback related negativity (FRN) was higher at
frontal, temporal and occipital electrodes in trials with monetary losses. In addition, trials
with monetary losses elicited larger P300 magnitudes than trials with monetary gains at
all electrode localizations.
Conclusions: All ERP components (except P300) were related to participants’
performance in the IGT. Amplitudes of P200 and P300 were associated with the
conscious recognition of the error during the decision-making. Performance data and
source analysis underline the importance of the medial prefrontal cortex when processing
feedback about monetary losses in the IGT.This research was supported by grants from the Spanish
Ministry of Science and Innovation (Ministerio de Ciencia y
Tecnología), European Regional Development Funds (ERDF)
and Ministry of Economy, Industry and Competitiveness
(Ministerio de Economía, Industria y Competitividad, Gobierno
de España). References: PSI2008-04394, PSI2017-88388-C4-1-R
and PSI2017-88388-C4-3-R
Uncovering Ecosystem Service Bundles through Social Preferences
Ecosystem service assessments have increasingly been used to support environmental management policies, mainly based on biophysical and economic indicators. However, few studies have coped with the social-cultural dimension of ecosystem services, despite being considered a research priority. We examined how ecosystem service bundles and trade-offs emerge from diverging social preferences toward ecosystem services delivered by various types of ecosystems in Spain. We conducted 3,379 direct face-to-face questionnaires in eight different case study sites from 2007 to 2011. Overall, 90.5% of the sampled population recognized the ecosystem’s capacity to deliver services. Formal studies, environmental behavior, and gender variables influenced the probability of people recognizing the ecosystem’s capacity to provide services. The ecosystem services most frequently perceived by people were regulating services; of those, air purification held the greatest importance. However, statistical analysis showed that socio-cultural factors and the conservation management strategy of ecosystems (i.e., National Park, Natural Park, or a non-protected area) have an effect on social preferences toward ecosystem services. Ecosystem service trade-offs and bundles were identified by analyzing social preferences through multivariate analysis (redundancy analysis and hierarchical cluster analysis). We found a clear trade-off among provisioning services (and recreational hunting) versus regulating services and almost all cultural services. We identified three ecosystem service bundles associated with the conservation management strategy and the rural-urban gradient. We conclude that socio-cultural preferences toward ecosystem services can serve as a tool to identify relevant services for people, the factors underlying these social preferences, and emerging ecosystem service bundles and trade-offs
The form of morphemes:MEG evidence from masked priming of two Hebrew templates
Studies of lexical access have benefited from comparisons between languages like English, which shows concatenative morphology, and Semitic languages showing non-concatenative morphology of roots and patterns. Morphological decomposition in Semitic has previously been probed using masked priming, originally developed to investigate concatenative morphology. However, studies conducted on Semitic languages have often targeted Semitic-specific questions, such as whether the root and the verbal template prime lexical access. The overall consequence of these studies for our understanding of lexical access remains unclear. In two experiments on Hebrew using MEG, we demonstrate that a verbal form which is orthographically and phonologically indistinguishable from non-verbal forms is primed by other verbs in the same template but not by similar nouns and adjectives. These results suggest that masked priming taps into more than just visual forms but reflects morphological content, even if this content is abstract, showing no distinct orthographic or phonological marking
Identification of Histological Patterns in Clinically Affected and Unaffected Palm Regions in Dupuytren's Disease
Dupuytren's disease is a fibro-proliferative disease characterized by a disorder of the extracellular matrix (ECM) and high myofibroblast proliferation. However, studies failed to determine if the whole palm fascia is affected by the disease. The objective of this study was to analyze several components of the extracellular matrix of three types of tissues—Dupuytren's diseased contracture cords (DDC), palmar fascia clinically unaffected by Dupuytren's disease contracture (NPF), and normal forehand fascia (NFF). Histological analysis, quantification of cells recultured from each type of tissue, mRNA microarrays and immunohistochemistry for smooth muscle actin (SMA), fibrillar ECM components and non-fibrillar ECM components were carried out. The results showed that DDC samples had abundant fibrosis with reticular fibers and few elastic fibers, high cell proliferation and myofibroblasts, laminin and glycoproteins, whereas NFF did not show any of these findings. Interestingly, NPF tissues had more cells showing myofibroblasts differentiation and more collagen and reticular fibers, laminin and glycoproteins than NFF, although at lower level than DDC, with similar elastic fibers than DDC. Immunohistochemical expression of decorin was high in DDC, whereas versican was highly expressed NFF, with no differences for aggrecan. Cluster analysis revealed that the global expression profile of NPF was very similar to DDC, and reculturing methods showed that cells corresponding to DDC tissues proliferated more actively than NPF, and NPF more actively than NFF. All these results suggest that NPF tissues may be affected, and that a modification of the therapeutic approach used for the treatment of Dupuytren's disease should be considered.This work was supported by CTS-115 (Tissue Engineering Group), University of Granada/Spain
Aesthetic and spiritual values of ecosystems: recognising the ontological and axiological plurality of cultural ecosystem 'services'.
This paper explores spiritual and aesthetic cultural values associated with ecosystems. We argue that these values are not best captured by instrumental or consequentialist thinking, and they are grounded in conceptions of nature that differ from the ecosystem services conceptual framework. To support our case, we engage with theories of the aesthetic and the spiritual, sample the discourse of ‘wilderness’, and provide empirical evidence from the recent UK National Ecosystem Assessment Follow-on Phase. We observe that accounts of spiritual and aesthetic value in Western culture are diverse and expressed through different media. We recognise that humans do benefit from their aesthetic and spiritual experiences of nature. However, aesthetic and spiritual understandings of the value of nature lead people to develop moral responsibilities towards nature and these are more significant than aesthetic and spiritual benefits from nature. We conclude that aesthetic and spiritual values challenge economic conceptions of ecosystems and of value (including existence value), and that an analysis of cultural productions and a plural-values approach are needed to evidence them appropriately for decision-making
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