Beneficial effects of word final stress in segmenting a new language: evidence from ERPs

Background: How do listeners manage to recognize words in an unfamiliar language? The physical continuity of the signal, in which real silent pauses between words are lacking, makes it a difficult task. However, there are multiple cues that can be exploited to localize word boundaries and to segment the acoustic signal. In the present study, word-stress was manipulated with statistical information and placed in different syllables within trisyllabic nonsense words to explore the result of the combination of the cues in an online word segmentation task. Results: The behavioral results showed that words were segmented better when stress was placed on the final syllables than when it was placed on the middle or first syllable. The electrophysiological results showed an increase in the amplitude of the P2 component, which seemed to be sensitive to word-stress and its location within words. Conclusion: The results demonstrated that listeners can integrate specific prosodic and distributional cues when segmenting speech. An ERP component related to word-stress cues was identified: stressed syllables elicited larger amplitudes in the P2 component than unstressed ones.

Structural factors impacting carrier transport and electroluminescence from Si nanocluster-sensitized Er ions.

We present an analysis of factors influencing carrier transport and electroluminescence (EL) at 1.5 µm from erbium-doped silicon-rich silica (SiOx) layers. The effects of both the active layer thickness and the Si excess content on the electrical excitation of erbium are studied. We demonstrate that when the thickness is decreased from a few hundred to tens of nanometers the conductivity is greatly enhanced. Carrier transport is well described in all cases by a Poole-Frenkel mechanism, while the thickness-dependent current density suggests an evolution of both density and distribution of trapping states induced by Si nanoinclusions. We ascribe this observation to stress-induced effects prevailing in thin films, which inhibit the agglomeration of Si atoms, resulting in a high density of sub-nm Si inclusions that induce traps much shallower than those generated by Si nanoclusters (Si-ncs) formed in thicker films. There is no direct correlation between high conductivity and optimized EL intensity at 1.5 µm. Our results suggest that the main excitation mechanism governing the EL signal is impact excitation, which gradually becomes more efficient as film thickness increases, thanks to the increased segregation of Si-ncs, which in turn allows more efficient injection of hot electrons into the oxide matrix. Optimization of the EL signal is thus found to be a compromise between conductivity and both number and degree of segregation of Si-ncs, all of which are governed by a combination of excess Si content and sample thickness. This material study has strong implications for many electrically driven devices using Si-ncs or Si-excess mediated EL.

Acetylation of cell wall is required for structural integrity of the leaf surface and exerts a global impact on plant stress responses.

The epidermis on leaves protects plants from pathogen invasion and provides a waterproof barrier. It consists of a layer of cells that is surrounded by thick cell walls, which are partially impregnated by highly hydrophobic cuticular components. We show that the Arabidopsis T-DNA insertion mutants of REDUCED WALL ACETYLATION 2 (rwa2), previously identified as having reduced O-acetylation of both pectins and hemicelluloses, exhibit pleiotrophic phenotype on the leaf surface. The cuticle layer appeared diffused and was significantly thicker and underneath cell wall layer was interspersed with electron-dense deposits. A large number of trichomes were collapsed and surface permeability of the leaves was enhanced in rwa2 as compared to the wild type. A massive reprogramming of the transcriptome was observed in rwa2 as compared to the wild type, including a coordinated up-regulation of genes involved in responses to abiotic stress, particularly detoxification of reactive oxygen species and defense against microbial pathogens (e.g., lipid transfer proteins, peroxidases). In accordance, peroxidase activities were found to be elevated in rwa2 as compared to the wild type. These results indicate that cell wall acetylation is essential for maintaining the structural integrity of leaf epidermis, and that reduction of cell wall acetylation leads to global stress responses in Arabidopsis.

Childhood adversities as specific contributors to the co-occurrence of posttraumatic stress and alcohol use disorders.

There is much evidence that alcohol use disorders (AUD) often co-occur with posttraumatic stress disorders (PTSD), and that the comorbid condition is associated with a more severe clinical profile than that of PTSD without AUD. However, little is known about the role of childhood adversities as specific risk factors for the development of AUD in individuals presenting with PTSD. The aim of the study was to explore whether specific stressors from the spectrum of trauma and childhood adversities contribute to the development of AUD among subjects with PTSD. From a large community sample, of N=140 individuals with PTSD, N=24 (17.14%) received an additional diagnosis of AUD with an onset after the onset of PTSD. Those with comorbid PTSD/AUD and those with PTSD only were compared regarding type and features of their trauma, childhood adversities and psychiatric comorbidity. Compared to PTSD alone, PTSD/AUD was associated with higher levels of stress in terms of childhood adversities; in particular, sexual abuse below the age of 16, but also with having been brought up in a foster home. PTSD/AUD was also associated with an earlier age of adverse events. Treatment of AUD should include standardized assessments of trauma, especially of trauma experienced during childhood.

Oxidative Stress and Antioxidant Activity in Hypothermia and Rewarming. Can RONS Modulate the Beneficial Effects of Therapeutic Hypothermia?

Hypothermia is a condition in which core temperature drops below the level necessary to maintain bodily functions. The decrease in temperature may disrupt some physiological systems of the body, including alterations in microcirculation and reduction of oxygen supply to tissues. The lack of oxygen can induce the generation of reactive oxygen and nitrogen free radicals (RONS), followed by oxidative stress, and finally, apoptosis and/or necrosis. Furthermore, since the hypothermia is inevitably followed by a rewarming process, we should also consider its effects. Despite hypothermia and rewarming inducing injury, many benefits of hypothermia have been demonstrated when used to preserve brain, cardiac, hepatic, and intestinal function against ischemic injury. This review gives an overview of the effects of hypothermia and rewarming on the oxidant/antioxidant balance and provides hypothesis for the role of reactive oxygen species in therapeutic hypothermia.

Compositional influence on the electrical performance of zinc indium tin oxide transparent thin-film transistors

In this work, zinc indium tin oxide layers with different compositions are used as the active layer of thin film transistors. This multicomponent transparent conductive oxide is gaining great interest due to its reduced content of the scarce indium element. Experimental data indicate that the incorporation of zinc promotes the creation of oxygen vacancies. In thin-film transistors this effect leads to a higher threshold voltage values. The field-effect mobility is also strongly degraded, probably due to coulomb scattering by ionized defects. A post deposition annealing in air reduces the density of oxygen vacancies and improves the fieldeffect mobility by orders of magnitude. Finally, the electrical characteristics of the fabricated thin-film transistors have been analyzed to estimate the density of states in the gap of the active layers. These measurements reveal a clear peak located at 0.3 eV from the conduction band edge that could be attributed to oxygen vacancies.

Posttraumatic stress avoidance symptoms as mediators in the development of alcohol use disorders after exposure to childhood sexual abuse in a Swiss community sample.

This study examined the role of posttraumatic stress disorder (PTSD) symptoms of re-experience, avoidance, and hyperarousal in the relationship between different types of trauma and alcohol use disorders (AUD). We used data from 731 trauma-exposed individuals who participated in the first wave of the PsyCoLaus-study. Trauma characteristics were assessed relatively to the occurrence of lifetime PTSD symptoms and AUD. The results suggest that lifetime and childhood sexual abuse as well as overall childhood trauma were directly linked to AUD and PTSD symptoms, in particular to avoidance symptoms. From single symptom clusters PTSD avoidance was found to specifically mediate the trauma-AUD pathway. Both childhood and sexual trauma strongly contribute to the comorbidity of PTSD and AUD and avoidance-type symptoms appear to play a central role in maintaining this association. Hence, the alleviation of avoidance symptoms might be an important target for therapeutic intervention among victims of sexual abuse before specific addiction treatment is initiated.

Discrepancies between clinical needs and helpseeking behaviors in co-occurring posttraumatic stress and alcohol use disorders.

OBJECTIVE: The aim of the study was to compare subjects dually diagnosed with posttraumatic stress disorder (PTSD) and alcohol use disorder (AUD) to those with only one or none of these conditions regarding helpseeking needs and behaviors. METHOD: Data from a large community sample (N=3694) were used to assess the associations among lifetime PTSD and AUD, other psychiatric disorders, clinical characteristics and lifetime helpseeking behaviors derived from a semi-structured interview. RESULTS: Comorbid individuals had more severe clinical profiles and were more impaired than individuals with either PTSD or AUD alone or those with no/other psychiatric conditions. However, they did not differ in overall helpseeking behavior from any other group. Those with comorbid PTSD/AUD were even less likely than the other groups to seek help for depression and anxiety disorders through specific treatment facilities or the use of prescribed psychotropic drugs. CONCLUSIONS: Despite a greater need for treatment the comorbid group did not seek more help than the others. Their lower use of prescribed drugs supports the self-medication hypothesis, suggesting that those individuals relieve their symptoms through higher alcohol use instead. Our findings underline the need for health care facilities to encourage helpseeking behavior in the aftermath of stressful life events.

Agricultural land use and human presence around breeding sites increase stress-hormone levels and decrease body mass in barn owl nestlings.

Human activities can have a suite of positive and negative effects on animals and thus can affect various life history parameters. Human presence and agricultural practice can be perceived as stressors to which animals react with the secretion of glucocorticoids. The acute short-term secretion of glucocorticoids is considered beneficial and helps an animal to redirect energy and behaviour to cope with a critical situation. However, a long-term increase of glucocorticoids can impair e.g. growth and immune functions. We investigated how nestling barn owls (Tyto alba) are affected by the surrounding landscape and by human activities around their nest sites. We studied these effects on two response levels: (a) the physiological level of the hypothalamus-pituitary-adrenal axis, represented by baseline concentrations of corticosterone and the concentration attained by a standardized stressor; (b) fitness parameters: growth of the nestlings and breeding performance. Nestlings growing up in intensively cultivated areas showed increased baseline corticosterone levels late in the season and had an increased corticosterone release after a stressful event, while their body mass was decreased. Nestlings experiencing frequent anthropogenic disturbance had elevated baseline corticosterone levels, an increased corticosterone stress response and a lower body mass. Finally, breeding performance was better in structurally more diverse landscapes. In conclusion, anthropogenic disturbance affects offspring quality rather than quantity, whereas agricultural practices affect both life history traits.