Zero-derived forms in the mental lexicon: Experimental evidence from Italian

Our paper investigates how zero-affixed verbal forms (specifically, denominal and deadjectival verbs) are processed by native speakers of Italian during visual word recognition. More specifically, we verify whether, and possibly to what extent, the processing of such forms differs from or resembles the processing of verbs resulting from two other productive word formation schemas in Italian, i. e., suffixation and parasynthesis. The interest of such a comparison lies in the fact that the three considered schemas behave similarly from a functional point of view, i. e.: i) they all change the category of the base, ii) they select the same base category (nouns and adjectives), and iii) they show similar semantic characteristics. However, this shared function is realized by means of different formal exponents (both overt and covert) which might imply different degrees of complexity. Crucially, suffixation and parasynthesis display an overt derivational marking, while zero-affixation obviously does not. On such premises, to verify whether the strength of connections between morphologically complex words and their bases is affected by the nature of the transcategorization marking (overt v s vs covert) or whether other factors play a more determining role, we conducted a psycholinguistic experiment involving a lexical decision task combined with the masked priming paradigm, which allows focusing on such relations in the mental lexicon. Results indicate that the processing of zero-affixed verbs resembles that of suffixed but differs from that of parasynthetic forms. We interpret such results discussing the possibility that the perception of a morphological relationship might depend less on the overtness of the marking, and more on the overall derivational complexity of the morphological process

Steady-State CO Oxidation on Pd(111): First-Principles Kinetic Monte Carlo Simulations and Microkinetic Analysis

Using a kinetic Monte Carlo (KMC) approach with parameters derived from first-principles calculations, we modeled the steady-state of CO oxidation on Pd(111), a prototypical catalytic system with various practical applications, including the treatment of automotive gas exhausts. Focusing on the metallic phase of the catalyst, we studied how the rate of CO oxidation depends on temperature and pressure, at fixed gas phase composition. Comparing the results of our simulations with experimental data, we found that all the qualitative features of this catalytic system are correctly reproduced by our model. We show that, when raising the temperature, the system transitions from a CO-poisoned regime with high apparent activation energy to a regime where the rate is almost independent of the temperature. The almost zero apparent activation energy at high temperature stems from approximately equal and opposite values of the O2 adsorption energy and dissociation barrier, as revealed by a simple microkinetic analysis. In the CO-poisoned regime, the precursor-mediated dissociative adsorption of oxygen plays a crucial role: we find that small changes (within DFT error) in the parameters controlling this elementary step have large effects on the kinetics of CO oxidation at low temperature

Alloys in catalysis: phase separation and surface segregation phenomena in response to the reactive environment

Alloys play a crucial role in several heterogeneous catalytic processes, and their applications are expected to rise rapidly. This is essentially related to the vast number of configurations and type of surface sites that multi-component materials can afford. It is well established that the chemical composition at the surface of an alloy usually differs from that in the bulk. This phenomenon, referred to as surface segregation, is largely controlled by the surface free energy. However, surface energy alone cannot safely predict the active surface state of a solid catalyst, since the contribution of other parameters such as size and support effects, as well as influence of the adsorbates, play a major role. This can lead to numerous surface configurations as for example over the length of a catalytic reactor, as the chemical potential of the gas phase changes continuously over the catalyst bed and hence different reactions may prevail at different catalyst bed segments. Thanks to the rapid improvement of the analytical surface science characterization techniques and theoretical methodologies, the potential effects induced by alloyed catalysts are better understood. For catalysis, the relevance of measurements performed on well-defined surfaces under idealized ultrahigh vacuum conditions has been questioned and studies in environments that closely resemble conditions of working alloy catalysts are needed. In this review we focus on experimental and theoretical studies related to in situ (operando) observations of surface segregation and phase separation phenomena taking place on the outermost surface layers of alloy catalysts. The combination of first principles theoretical treatment and in situ observation opens up new perspectives of designing alloy catalysts with tailored properties

Utilização de cerca elétrica para contenção de aves no sistema semi-confinado de produção.

bitstream/item/58351/1/CUsersPiazzonDocuments266.pd

Ag-Cu catalysts for ethylene epoxidation: Selectivity and activity descriptors

Ag-Cu alloy catalysts for ethylene epoxidation have been shown to yield higher selectivity towards ethylene oxide compared to pure Ag, the unique catalyst employed in the industrial process. Previous studies showed that under oxidizing conditions Cu forms oxide layers on top of Ag. Using first-principles atomistic simulations based on density functional theory, we investigate the reaction mechanism on the thin oxide layer structures and establish the reasons for the improved selectivity. We extend the range of applicability of the selectivity descriptor proposed by Kokalj et al. [J. Catal. 254, 304 (2008)], based on binding energies of reactants, intermediates, and products, by refitting its parameters so as to include thin oxide layer catalysts. We show that the selectivity is mainly controlled by the relative strength of the metal-carbon vs. metal-oxygen bonds, while the height of the reaction barriers mostly depend on the binding energy of the common oxametallacycle intermediate. (C) 2013 AIP Publishing LLC

Stress dynamically regulates behavior and glutamatergic gene expression in hippocampus by opening a window of epigenetic plasticity

Excitatory amino acids play a key role in both adaptive and deleterious effects of stressors on the brain, and dysregulated glutamate homeostasis has been associated with psychiatric and neurological disorders. Here, we elucidate mechanisms of epigenetic plasticity in the hippocampus in the interactions between a history of chronic stress and familiar and novel acute stressors that alter expression of anxiety- and depressive-like behaviors. We demonstrate that acute restraint and acute forced swim stressors induce differential effects on these behaviors in naive mice and in mice with a history of chronic-restraint stress (CRS). They reveal a key role for epigenetic up- and down-regulation of the putative presynaptic type 2 metabotropic glutamate (mGlu2) receptors and the postsynaptic NR1/NMDA receptors in the hippocampus and particularly in the dentate gyrus (DG), a region of active neurogenesis and a target of antidepressant treatment. We show changes in DG long-term potentiation (LTP) that parallel behavioral responses, with habituation to the same acute restraint stressor and sensitization to a novel forced-swim stressor. In WT mice after CRS and in unstressed mice with a BDNF loss-of-function allele (BDNF Val66Met), we show that the epigenetic activator of histone acetylation, P300, plays a pivotal role in the dynamic up- and down-regulation of mGlu2 in hippocampus via histone-3-lysine-27-acetylation (H3K27Ac) when acute stressors are applied. These hippocampal responses reveal a window of epigenetic plasticity that may be useful for treatment of disorders in which glutamatergic transmission is dysregulated

Decline in memory, visuospatial ability and crystalized cognitive abilities in older adults:Normative aging or terminal decline?

The aim of this study is to explore the pattern of change in multiple measures of cognitive abilities in a sample of oldest-old adults, comparing two different time metrics (chronological age and time to death) and therefore examining both underlying conceptual assumptions (age-related change and terminal decline). Moreover, the association with individual characteristics as sex, education, and dementia diagnosis was also examined. Measures of cognitive status (Mini-Mental State Examination and the Swedish Clock Test) and tests of crystallized (knowledge and synonyms), memory (verbal memory, nonverbal long-term memory, recognition and correspondence, and short-term memory), and visuospatial ability were included. The sample consisted of 671 older Swedish adult participants of the OCTO Twin Study. Linear mixed models with random coefficients were used to analyse change patterns and BIC indexes were used to compare models. Results showed that the time to death model was the best option in analyses of change in all the cognitive measures considered (except for the Information Test). A significant cognitive decline over time was found for all variables. Individuals diagnosed with dementia had lower scores at the study entrance and a faster decline. More educated individuals performed better in all the measures of cognition at study entry than those with poorer education, but no differences were found in the rate of change. Differences were found in age, sex, or time to death at baseline across the different measures. These results support the terminal decline hypothesis when compared to models assuming that cognitive changes are driven by normative aging processes

An international evaluation of cognitive reserve and memory changes in early old age in ten European countries

BACKGROUND: Cognitive reserve was postulated to explain individual differences in susceptibility to ageing, offering apparent protection to those with higher education. We investigated the association between education and change in memory in early old age. METHODS: Immediate and delayed memory scores from over 10,000 individuals aged 65 years and older, from 10 countries of the Survey of Health, Ageing and Retirement in Europe (SHARE), were modeled as a function of time in the study over an 8-year period, fitting independent latent growth models (LGM). Education was used as a marker of cognitive reserve and evaluated in associations with memory performance and rate of change, while accounting for income, general health, smoking, body mass index (BMI), sex and baseline age. RESULTS: In most countries, more educated individuals performed better on both memory tests at baseline, compared to those less educated. However, education was not protective against faster decline, except for in Spain for both immediate and delayed recall (0.007 (SE=0.003) & 0.006 (SE=0.002), and Switzerland for immediate recall 0.006 (SE=0.003). Interestingly, highly educated Italian respondents had slightly faster declines in immediate recall (-0.006 (SE=0.003)). CONCLUSIONS: We found weak evidence of a protective effect of education on memory change in most European samples, although there was a positive association with memory performance at individuals' baseline assessment