Refine
Has Fulltext
- no (1399) (remove)
Year of publication
- 2017 (1399) (remove)
Document Type
- Article (1399) (remove)
Is part of the Bibliography
- yes (1399)
Keywords
- stars: massive (11)
- Germany (10)
- Holocene (9)
- German (8)
- stars: early-type (8)
- adolescence (7)
- stars: winds, outflows (7)
- Arabidopsis thaliana (6)
- Climate change (6)
- Depression (6)
Institute
- Institut für Biochemie und Biologie (254)
- Institut für Geowissenschaften (229)
- Institut für Physik und Astronomie (215)
- Institut für Chemie (115)
- Department Psychologie (98)
- Department Sport- und Gesundheitswissenschaften (70)
- Institut für Ernährungswissenschaft (47)
- Institut für Mathematik (44)
- Department Linguistik (43)
- Wirtschaftswissenschaften (24)
Theoretical models and preceding studies have described age-related alterations in neuronal activation of frontoparietal regions in a working memory (WM)load-dependent manner. However, to date, underlying neuronal mechanisms of these WM load-dependent activation changes in aging remain poorly understood. The aim of this study was to investigate these mechanisms in terms of effective connectivity by application of dynamic causal modeling with Bayesian Model Selection. Eighteen healthy younger (age: 20-32 years) and 32 older (60-75 years) participants performed an n-back task with 3 WM load levels during functional magnetic resonance imaging (fMRI). Behavioral and conventional fMRI results replicated age group by WM load interactions. Importantly, the analysis of effective connectivity derived from dynamic causal modeling, indicated an age-and performance-related reduction in WM load-dependent modulation of connectivity from dorsolateral prefrontal cortex to inferior parietal lobule. This finding provides evidence for the proposal that age-related WM decline manifests as deficient WM load-dependent modulation of neuronal top-down control and can integrate implications from theoretical models and previous studies of functional changes in the aging brain.
Background: The aim of the present study was to investigate the psychometric characteristics of the Perceived Stress Scale (PSS) in a sample of dementia patients and their spousal caregivers. Methods: We investigated the reliability and validity of the 14-item PSS in a sample of 80 couples, each including one spouse who had been diagnosed with mild to moderate dementia (mean age 75.55, SD = 5.85, 38.7% female) and one spousal caregiver (mean age 73.06, SD = 6.75, 61.3% female). We also examined the factor structure and sensitivity of the scale with regard to gender differences. Results: Exploratory factor analysis of the PSS revealed a two-factor solution for the scale; the first factor reflected general stress while the second factor consisted of items reflecting the perceived ability to cope with stressors. A confirmatory factor analysis verified that the data were a better fit for the two-factor model than a one-factor model. The two factors of the PSS showed good reliability for patients as well as for caregivers ranging between alpha = 0.73 and alpha = 0.82. Perceived stress was significantly positively correlated with depressive symptomatology in both caregivers and patients. Mean PSS scores did not significantly differ between male and female patients nor did they differ between male and female caregivers. Conclusion: The present data indicate that the PSS provides a reliable and valid measure of perceived stress in dementia patients and their caregivers.
Substance-dependent individuals often lack the ability to adjust decisions flexibly in response to the changes in reward contingencies. Prediction errors (PEs) are thought to mediate flexible decision-making by updating the reward values associated with available actions. In this study, we explored whether the neurobiological correlates of PEs are altered in alcohol dependence. Behavioral, and functional magnetic resonance imaging (fMRI) data were simultaneously acquired from 34 abstinent alcohol-dependent patients (ADP) and 26 healthy controls (HC) during a probabilistic reward-guided decision-making task with dynamically changing reinforcement contingencies. A hierarchical Bayesian inference method was used to fit and compare learning models with different assumptions about the amount of task-related information subjects may have inferred during the experiment. Here, we observed that the best-fitting model was a modified Rescorla-Wagner type model, the “double-update” model, which assumes that subjects infer the knowledge that reward contingencies are anti-correlated, and integrate both actual and hypothetical outcomes into their decisions. Moreover, comparison of the best-fitting model's parameters showed that ADP were less sensitive to punishments compared to HC. Hence, decisions of ADP after punishments were loosely coupled with the expected reward values assigned to them. A correlation analysis between the model-generated PEs and the fMRI data revealed a reduced association between these PEs and the BOLD activity in the dorsolateral prefrontal cortex (DLPFC) of ADP. A hemispheric asymmetry was observed in the DLPFC when positive and negative PE signals were analyzed separately. The right DLPFC activity in ADP showed a reduced correlation with positive PEs. On the other hand, ADP, particularly the patients with high dependence severity, recruited the left DLPFC to a lesser extent than HC for processing negative PE signals. These results suggest that the DLPFC, which has been linked to adaptive control of action selection, may play an important role in cognitive inflexibility observed in alcohol dependence when reinforcement contingencies change. Particularly, the left DLPFC may contribute to this impaired behavioral adaptation, possibly by impeding the extinction of the actions that no longer lead to a reward.
Background: The patterns of benzodiazepine prescriptions in older adults are of general and scientific interest as they are not yet well understood. The aim of this study was to compare the prescription patterns of benzodiazepines in elderly people in Germany to determine the share or proportion treated by general practitioners (GP) and neuropsychiatrists (NP). Methods: This study included 31,268 and 6,603 patients between the ages of 65 and 100 with at least one benzodiazepine prescription in 2014 from GP and NP, respectively. Demographic data included age, gender, and type of health insurance coverage. The share of elderly people with benzodiazepine prescriptions was estimated in different age and disease groups for both GP and NP patients. The share of the six most commonly prescribed drugs was also calculated for each type of practice. Results: The share of people taking benzodiazepines prescribed by GP increased from 3.2% in patients aged between 65 and 69 years to 8.6% in patients aged between 90 and 100 years, whereas this share increased from 5.4% to 7.1% in those seen by NP. Benzodiazepines were frequently used by patients suffering from sleep disorders (GP: 33.9%; NP: 5.5%), depression (GP: 17.9%; NP: 29.8%), and anxiety disorders (GP: 14.5%; NP: 22.8%). Lorazepam (30.3%), oxazepam (24.7%), and bromazepam (24.3%) were the three most commonly prescribed drugs for GP patients. In contrast, lorazepam (60.4%), diazepam (14.8%), and oxazepam (11.2%) were those more frequently prescribed to NP patients. Conclusion: Prescription patterns of benzodiazepine in the elderly varied widely between GP and NP.
Reduced Interface-Mediated Recombination for High Open-Circuit Voltages in CH3NH3PbI3 Solar Cells
(2017)
Perovskite solar cells with all-organic transport layers exhibit efficiencies rivaling their counterparts that employ inorganic transport layers, while avoiding high-temperature processing. Herein, it is investigated how the choice of the fullerene derivative employed in the electron-transporting layer of inverted perovskite cells affects the open-circuit voltage (V-OC). It is shown that nonradiative recombination mediated by the electron-transporting layer is the limiting factor for the V-OC in the cells. By inserting an ultrathin layer of an insulating polymer between the active CH3NH3PbI3 perovskite and the fullerene, an external radiative efficiency of up to 0.3%, a V-OC as high as 1.16 V, and a power conversion efficiency of 19.4% are realized. The results show that the reduction of nonradiative recombination due to charge-blocking at the perovskite/organic interface is more important than proper level alignment in the search for ideal selective contacts toward high V-OC and efficiency.
Objectives: In patients with early-stage dementia and their caregiving partners, reciprocal dyadic coping (DC) is crucial for preventing or reducing depressive symptoms in both partners. This study examines the relationships between ‘own DC’ and ‘perceived partner DC’ with depressive symptoms in couples coping with dementia on individual (actor effects) and cross-person (partner effects) levels.
Method: 164 individuals (82 patients with early-stage dementia and their 82 caregiving partners; ND = 82 dyads) participated in this prospective study with measures (DC, depressive symptoms, and dementia severity) taken at baseline and at six months. Each partner evaluated their own and the perceived partner DC. Actor–partner interdependence models were applied to the resulting four independent evaluations.
Results: Results differed substantially between patients and caregivers. DC was significantly related to patients’ but not to caregivers’ depressive symptoms, when adjustments were made for individual coping. Perceived partner DC showed a negative association with depressive symptoms in patients, whereas own DC was adversely related for actor as well as for partner effects across individuals.
Conclusion: The adverse association between the own DC of the caregiver and the patient on depressive symptoms of the patient might be due to inappropriate efforts or to the loss of autonomy as a care-receiver. DC is important in both patients and caregivers, as shown by the negative association between perceived partner DC and depressive symptoms in the patients, which might inform interventions that target the couple as a whole.
On the ambiguity of interaction and nonlinear main effects in a regime of dependent covariates
(2017)
The analysis of large experimental datasets frequently reveals significant interactions that are difficult to interpret within the theoretical framework guiding the research. Some of these interactions actually arise from the presence of unspecified nonlinear main effects and statistically dependent covariates in the statistical model. Importantly, such nonlinear main effects may be compatible (or, at least, not incompatible) with the current theoretical framework. In the present literature, this issue has only been studied in terms of correlated (linearly dependent) covariates. Here we generalize to nonlinear main effects (i.e., main effects of arbitrary shape) and dependent covariates. We propose a novel nonparametric method to test for ambiguous interactions where present parametric methods fail. We illustrate the method with a set of simulations and with reanalyses (a) of effects of parental education on their children’s educational expectations and (b) of effects of word properties on fixation locations during reading of natural sentences, specifically of effects of length and morphological complexity of the word to be fixated next. The resolution of such ambiguities facilitates theoretical progress.
The Arabidopsis thaliana NAC transcription factor JUNGBRUNNEN1 (AtJUB1) regulates growth by directly repressing GA3ox1 and DWF4, two key genes involved in gibberellin (GA) and brassinosteroid (BR) biosynthesis, respectively, leading to GA and BR deficiency phenotypes. AtJUB1 also reduces the expression of PIF4, a bHLH transcription factor that positively controls cell elongation, while it stimulates the expression of DELLA genes, which are important repressors of growth. Here, we extend our previous findings by demonstrating that AtJUB1 induces similar GA and BR deficiency phenotypes and changes in gene expression when overexpressed in tomato (Solanum lycopersicum). Importantly, and in accordance with the growth phenotypes observed, AtJUB1 inhibits the expression of growth-supporting genes, namely the tomato orthologs of GA3ox1, DWF4 and PIF4, but activates the expression of DELLA orthologs, by directly binding to their promoters. Overexpression of AtJUB1 in tomato delays fruit ripening, which is accompanied by reduced expression of several ripeningrelated genes, and leads to an increase in the levels of various amino acids (mostly proline, beta-alanine, and phenylalanine), gamma-aminobutyric acid (GABA), and major organic acids including glutamic acid and aspartic acid. The fact that AtJUB1 exerts an inhibitory effect on the GA/BR biosynthesis and PIF4 genes but acts as a direct activator of DELLA genes in both, Arabidopsis and tomato, strongly supports the model that the molecular constituents of the JUNGBRUNNEN1 growth control module are considerably conserved across species.
The process of starch granule formation in leaves of Arabidopsis ( Arabidopsis thaliana) is obscure. Besides STARCH SYNTHASE4 (SS4), the PLASTIDIAL PHOSPHORYLASE (PHS1) also seems to be involved, since dpe2-1/phs1a double mutants lacking both PHS1 and the cytosolic DISPROPORTIONATING ENZYME2 (DPE2) displayed only one starch granule per chloroplast under normal growth conditions. For further studies, a dpe2-1/phs1a/ss4 triple mutant and various combinations of double mutants were generated and metabolically analyzed with a focus on starch metabolism. The dpe2-1/phs1a/ ss4 mutant revealed a massive starch excess phenotype. Furthermore, these plants grown under 12 h of light/12 h of dark harbored a single large and spherical starch granule per plastid. The number of starch granules was constant when the light/dark regime was altered, but this was not observed in the parental lines. With regard to growth, photosynthetic parameters, and metabolic analyses, the triple mutant additionally displayed alterations in comparison with ss4 and dpe21/phs1a. The results clearly illustrate that PHS1 and SS4 are differently involved in starch granule formation and do not act in series. However, SS4 appears to exert a stronger influence. In connection with the characterized double mutants, we discuss the generation of starch granules and the observed formation of spherical starch granules.