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Sökning: WFRF:(Starke J.)

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  • Hibar, D. P., et al. (författare)
  • Cortical abnormalities in bipolar disorder: An MRI analysis of 6503 individuals from the ENIGMA Bipolar Disorder Working Group
  • 2018
  • Ingår i: Molecular Psychiatry. - 1359-4184 .- 1476-5578. ; 23:4, s. 932-942
  • Tidskriftsartikel (refereegranskat)abstract
    • Despite decades of research, the pathophysiology of bipolar disorder (BD) is still not well understood. Structural brain differences have been associated with BD, but results from neuroimaging studies have been inconsistent. To address this, we performed the largest study to date of cortical gray matter thickness and surface area measures from brain magnetic resonance imaging scans of 6503 individuals including 1837 unrelated adults with BD and 2582 unrelated healthy controls for group differences while also examining the effects of commonly prescribed medications, age of illness onset, history of psychosis, mood state, age and sex differences on cortical regions. In BD, cortical gray matter was thinner in frontal, temporal and parietal regions of both brain hemispheres. BD had the strongest effects on left pars opercularis (Cohen's d='0.293; P=1.71 × 10 '21), left fusiform gyrus (d='0.288; P=8.25 × 10 '21) and left rostral middle frontal cortex (d='0.276; P=2.99 × 10 '19). Longer duration of illness (after accounting for age at the time of scanning) was associated with reduced cortical thickness in frontal, medial parietal and occipital regions. We found that several commonly prescribed medications, including lithium, antiepileptic and antipsychotic treatment showed significant associations with cortical thickness and surface area, even after accounting for patients who received multiple medications. We found evidence of reduced cortical surface area associated with a history of psychosis but no associations with mood state at the time of scanning. Our analysis revealed previously undetected associations and provides an extensive analysis of potential confounding variables in neuroimaging studies of BD. © 2018 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.
  • Aprojanz, J., et al. (författare)
  • High-Mobility Epitaxial Graphene on Ge/Si(100) Substrates
  • 2020
  • Ingår i: ACS applied materials & interfaces. - : The American Chemical Society (ACS). - 1944-8244. ; 12:38, s. 43065-43072
  • Tidskriftsartikel (refereegranskat)abstract
    • Graphene was shown to reveal intriguing properties of its relativistic two-dimensional electron gas; however, its implementation to microelectronic applications is missing to date. In this work, we present a comprehensive study of epitaxial graphene on technologically relevant and in a standard CMOS process achievable Ge(100) epilayers grown on Si(100) substrates. Crystalline graphene monolayer structures were grown by means of chemical vapor deposition (CVD). Using angle-resolved photoemission spectroscopy and in situ surface transport measurements, we demonstrate their metallic character both in momentum and real space. Despite numerous crystalline imperfections, e.g., grain boundaries and strong corrugation, as compared to epitaxial graphene on SiC(0001), charge carrier mobilities of 1 × 104 cm2/Vs were obtained at room temperature, which is a result of the quasi-charge neutrality within the graphene monolayers on germanium and not dependent on the presence of an interface oxide. The interface roughness due to the facet structure of the Ge(100) epilayer, formed during the CVD growth of graphene, can be reduced via subsequent in situ annealing up to 850 °C coming along with an increase in the mobility by 30%. The formation of a Ge(100)-(2 × 1) structure demonstrates the weak interaction and effective delamination of graphene from the Ge/Si(100) substrate.
  • Baringhaus, J., et al. (författare)
  • Bipolar gating of epitaxial graphene by intercalation of Ge
  • 2014
  • Ingår i: Applied Physics Letters. - : American Institute of Physics (AIP). - 0003-6951. ; 104:26
  • Tidskriftsartikel (refereegranskat)abstract
    • In this study, the ambivalent behavior of Ge intercalation is studied by means of scanning tunneling microscopy and spectroscopy as well as local 4-point probe transport measurements. In quantitative agreement with angle-resolved photoemission experiments, both p-and n-type doped graphene areas and their doping level were identified by local spectroscopy. The p-doped areas appear higher by 2 angstrom with respect to the n-doped areas suggesting incorporation of thicker Ge-layers accompanied by a modified coupling to the initial SiC-surface. Furthermore, the sheet resistance was measured on each of the patches separately. The intrinsic imbalance between the carrier types in the different areas is well reflected by the transport study. The process of intercalation does not affect the transport properties in comparison to pristine graphene pointing to a sufficient homogeneity of the decoupled graphene layer. Transport measurements across chemically gated pn-junctions reveal increased resistances, possibly due to enlarged tunneling barriers. (C) 2014 AIP Publishing LLC.
  • Eberlein, Christian, et al. (författare)
  • Immediate response mechanisms of Gram-negative solvent-tolerant bacteria to cope with environmental stress : cis-trans isomerization of unsaturated fatty acids and outer membrane vesicle secretion
  • 2018
  • Ingår i: Applied Microbiology and Biotechnology. - 0175-7598 .- 1432-0614. ; 102:6, s. 2583-2593
  • Forskningsöversikt (refereegranskat)abstract
    • Bacteria have evolved an array of adaptive mechanisms enabling them to survive and grow in the presence of different environmental stresses. These mechanisms include either modifications of the membrane or changes in the overall energy status, cell morphology, and cell surface properties. Long-term adaptations are dependent on transcriptional regulation, the induction of anabolic pathways, and cell growth. However, to survive sudden environmental changes, bacterial short-term responses are essential to keep the cells alive after the occurrence of an environmental stress factor such as heat shock or the presence of toxic organic solvents. Thus far, two main short-term responses are known. On the one hand, a fast isomerization of cis into trans unsaturated fatty leads to a quick rigidification of the cell membrane, a mechanism known in some genera of Gram-negative bacteria. On the other hand, a fast, effective, and ubiquitously present countermeasure is the release of outer membrane vesicles (OMVs) from the cell surface leading to a rapid increase in cell surface hydrophobicity and finally to the formation of cell aggregates and biofilms. These immediate response mechanisms just allow the bacteria to stay physiologically active and to employ long-term responses to assure viability upon changing environmental conditions. Here, we provide insight into the two aforementioned rapid adaptive mechanisms affecting ultimately the cell envelope of Gram-negative bacteria.
  • Hetzel, M., et al. (författare)
  • Nanowire Reconstruction on the 4H-SiC(1-102) Surface
  • 2007
  • Ingår i: Silicon Carbide and Related Materials 2006. - : Trans Tech Publications Inc.. ; , s. 529-532
  • Konferensbidrag (refereegranskat)abstract
    • Ordered reconstruction phases on the 4H-SiC(1102) surface have been investigated usinglow-energy electron diffraction (LEED), Auger electron spectroscopy (AES) and scanning tunnelingmicroscopy (STM). After initial hydrogen etching, the samples were prepared by Si deposition andannealing in ultra-high vacuum (UHV). Two distinct reconstruction phases develop upon annealing,first with a (2×1), and at higher temperatures with a c(2×2) LEED pattern. After further annealingthe fractional order LEED spots vanish and a (1x1) pattern develops. For the (2×1) phase, STMmicrographs show that adatom chains develop on large flat terraces, which in view of AES consistof additional Si. These highly linear and equidistant chains represent a self-assembled well-orderedpattern of nanowires developing due to the intrinsic structure of the 4H-SiC(1102) surface. For thec(2×2) phase AES indicates a surface composition close to the bulk stoichiometry. For the (1×1)phase a further Si depletion is observed.
  • Ineland, J., et al. (författare)
  • Factors associated with positive work experience among professionals supporting people with intellectual disabilities: a comparative analysis of three welfare organisations in Sweden
  • 2020
  • Ingår i: International Journal of Developmental Disabilities. - : Taylor & Francis. - 2047-3869.
  • Tidskriftsartikel (refereegranskat)abstract
    • Given the crucial role professionals play in maintaining the well-being of people with intellectual disabilities, their views on work satisfaction are relevant to analyse. A comparative analysis that takes into account the support provided in different welfare organisations can be of certain importance. The aim is to analyse the most common aspects of professional work satisfaction in work with people with intellectual disabilities in schools, healthcare, and social services, and to apply a comparative analysis of such experience taking into account respondents' organisational affiliations. Data were collected using a digital questionnaire. Given the aim of the study, we drew on one open-ended question: 'describe aspects of your work that are most satisfactory for you'. The analysis shows that respondents associated positive work experience with seven aspects: autonomy, competence, nature of the work, collaboration, trust and recognition, work environment, and service users. Findings indicate that discretion is an important facet of work satisfaction among respondents in all three organisations. Flexibility, autonomy in decision-making, the ability to plan and act within certain institutional and legal frameworks, and the ability to prioritise among daily work assignments are empirical examples of this.
  • Kristenson, Margareta, 1950-, et al. (författare)
  • Psychobiological mechanisms of socioeconomic differences in health
  • 2004
  • Ingår i: Social Science and Medicine. - 0277-9536 .- 1873-5347. ; 58:8, s. 1511-1522
  • Tidskriftsartikel (refereegranskat)abstract
    • The association between low socioeconomic status and poor health is well established. Empirical studies suggest that psychosocial factors are important mediators for these effects, and that the effects are mediated by psychobiological mechanisms related to stress physiology. The objective of this paper is to explore these psychobiological mechanisms. Psychobiological responses to environmental challenges depend on acquired expectancies (learning) of the relations between responses and stimuli. The stress response occurs whenever an individual is faced with a challenge. It is an essential element in the total adaptive system of the body, and necessary for adaptation, performance and survival. However, a period of recovery is necessary to rebalance and to manage new demands. Individuals with low social status report more environmental challenges and less psychosocial resources. This may lead to vicious circles of learning to expect negative outcomes, loss of coping ability, strain, hopelessness and chronic stress. This type of learning may interfere with the recovery processes, leading to sustained psychobiological activation and loss of dynamic capacity to respond to new challenges. Psychobiological responses and health effects in humans and animals depend on combinations of demands and expected outcomes (coping, control). In studies of humans with chronic psychosocial stress, and low SES, cortisol baseline levels were raised, and the cortisol response to acute stress attenuated. Low job control was associated with insufficient recovery of catecholamines and cortisol, and a range of negative health effects. Biological effects of choice of lifestyle, which also depends on the acquired outcome expectancies, reinforce these direct psychobiological effects on health. The paper concludes that sustained activation and loss of capacity to respond to a novel stressor could be a cause of the higher risk of illness and disease found among people with lower SES.
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