Multiple ionization of argon via multi-XUV-photon absorption induced by 20-GW high-order harmonic laser pulses

We report the observation of multiple ionization of argon through multi-XUV-photon absorption induced by an unprecedentedly powerful laser driven high-order harmonic generation source. Comparing the measured intensity dependence of the yield of the different argon charge states with numerical calculations we can infer the different channels—direct and sequential—underlying the interaction. While such studies were feasible so far only with free electron laser (FEL) sources, this paper connects highly nonlinear XUV processes with the ultrashort time scales inherent to the harmonic pulses and highlights the advanced perspectives of emerging large scale laser research infrastructures

Aging is associated with a prefrontal lateral-medial shift during picture-induced negative affect

The capacity to adaptively respond to negative emotion is in part dependent upon lateral areas of the prefrontal cortex (PFC). Lateral PFC areas are particularly susceptible to age-related atrophy, which affects executive function (EF). We used structural and functional magnetic resonance imaging (MRI) to test the hypothesis that older age is associated with greater medial PFC engagement during processing of negative information, and that this engagement is dependent upon the integrity of grey matter structure in lateral PFC as well as EF. Participants (n = 64, 38–79 years) viewed negative and neutral scenes while in the scanner, and completed cognitive tests as part of a larger study. Grey matter probability (GMP) was computed to index grey matter integrity. FMRI data demonstrated less activity in the left ventrolateral PFC (VLPFC) and greater ventromedial PFC (VMPFC) activity with increasing age during negative-picture viewing. Age did not correlate with amygdala responding. GMP in VLPFC and EF were negatively associated with VMPFC activity. We conclude that this change from lateral to medial PFC engagement in response to picture-induced negative affect reflects decreased reliance on executive function-related processes, possibly associated with reduced grey matter in lateral PFC, with advancing age to maintain emotional functioning

Positive Affect Predicts Cerebral Glucose Metabolism in Late Middle-aged Adults.

Positive affect is associated with a number of health benefits; however, few studies have examined the relationship between positive affect and cerebral glucose metabolism, a key energy source for neuronal function and a possible index of brain health. We sought to determine if positive affect was associated with cerebral glucose metabolism in late middle-aged adults (n = 133). Participants completed the positive affect subscale of the Center for Epidemiological Studies Depression Scale at two time points over a two-year period and underwent 18F-fluorodeoxyglucose-positron emission tomography scanning. After controlling for age, sex, perceived health status, depressive symptoms, anti-depressant use, family history of Alzheimer’s disease, APOE ε4 status and interval between visits, positive affect was associated with greater cerebral glucose metabolism across para-/limbic, frontal, temporal and parietal regions. Our findings provide evidence that positive affect in late midlife is associated with greater brain health in regions involved in affective processing and also known to be susceptible to early neuropathological processes. The current findings may have implications for interventions aimed at increasing positive affect to attenuate early neuropathological changes in at-risk individuals

Fish, docosahexaenoic acid and Alzheimer’s disease

Cognitive decline in the elderly, particularly Alzheimer’s disease (AD), is a major socio-economic and healthcare concern. We review here the literature on one specific aspect of diet affecting AD, that of the ω3 fatty acids, particularly the brain’s principle ω3 fatty acid – docosahexaenoic acid (DHA). DHA has deservedly received wide attention as a nutrient supporting both optimal brain development and for cardiovascular health. Our aim here is to critically assess the quality of the present literature as well as the potential of ω3 fatty acids to treat or delay the onset of AD. We start with a brief description of cognitive decline in the elderly, followed by an overview of well recognized biological functions of DHA. We then turn to epidemiological studies, which are largely supportive of protective effects of fish and DHA against risk of AD. However, biological studies, including blood and brain DHA analyses need careful interpretation and further investigation, without which the success of clinical trials with DHA may continue to struggle. We draw attention to some of the methodological issues that need resolution as well as an emerging mechanism that may explain how DHA could be linked to protecting brain function in the elderly

Ultrafast reversible phase change in GeSb films for erasable optical storage

Amorphous-to-crystalline and crystalline-to-amorphous transformations are triggered in GeSb thin films by irradiation with femtosecond and picosecond laser pulses. Phase changes are accompanied with optical contrast and therefore the feasibility of phase-change optical recording at ultrafast rates is demonstrated for the first time. The phase reversal by ultrashort pulses seems to be related to the dependence of the degree of undercooling prior to solidification on the irradiation energy density.Peer Reviewe