267 research outputs found
Typology of streams in Germany based on benthic invertebrates: Ecoregions, zonation, geology and substrate
AbstractBased on 390 benthic invertebrate samples from near-natural streams in Germany we defined eight stream type groups by Non-metric multidimensional scaling (NMS). The taxa lists were restricted to Mollusca, Ephemeroptera, Odonata, Plecoptera, Coleoptera and Trichoptera species and evaluated on presence/absence level. At genus level, streams located in the lowlands differ from streams in lower mountainous areas and the Alps, while the two latter groups were undistinguishable. At species level, a clear separation of different stream size classes is visible in the lowlands; a second gradient is related to the bottom substrate. Streams in the Alps can be distinguished from streams in lower mountainous areas at species level. Within the lower mountainous regions a size gradient is detectable, a less obvious gradient indicates catchment geology. The resulting âbottom-upâ stream typology is compared to other stream typological systems in Germany
Homologous Deformation of the Effelsberg 100-m Telescope Determined with a Total Station
Due to gravitation the main reflector of the Effelsberg 100-m telescope of the Max Planck Institute for Radio Astronomy is deformed whenever it is tilted from zenith to arbitrary elevation angles. However, the resulting shape always is a paraboloid again, though with different parameters, a phenomenon which is called homologous deformation. In summer 2008, we have carried out measurements with a total station to determine the magnitude of these deformations in order to evaluate existing assumptions provided by the manufacturer from the telescope's design phase. The measurements are based on a newly developed approach with a Leica TCRP 1201 total station mounted head down near the subreflector. Mini-retro-reflectors are placed at various locations on the paraboloid itself and on the subreflector support structure. The results indicate that the measurement setup is suitable for the purpose and provides the information needed for a determination of elevation dependent delay corrections. The focal length changes only by about 8 mm when the telescope is tilted from 90. to 7.5. elevation angle
Distribution of structure and lignin within growth rings of Norway spruce
A radial core from a Norway spruce (Picea abies (L.) Karst.) estimated to be about 107years old was cut from a board and was analyzed for density and microfibril angle (MFA). Furthermore, cell geometry, wall thickness and lignin distribution were analyzed on three selected growth rings in detail. Intra-ring differences in the density profiles are also true for cell wall thicknesses as well as radial and tangential lumen diameters. A higher MFA was found for earlywood with a slow decrease toward the latewood region. The lignin was found to remain rather constant throughout the growth rings, which suggests a constant chemical composition of the cell wall material within the growth ring. From the recorded datasets on a cellular level, it can be concluded that the main adaptation regarding structure-property relationships toward the optimization of water transport and mechanical stability is mainly achieved at the cell leve
Informal caregivers during the COVID-19 pandemic perceive additional burden: findings from an ad-hoc survey in Germany
Background: While the relation between care involvement of informal caregivers and caregiver burden is well-known, the additional psychosocial burden related to care involvement during the COVID-19 pandemic has not yet been investigated.
Methods: A total of 1000 informal caregivers, recruited offline, participated in a cross-sectional online survey from April 21 to May 2, 2020. Questionnaires were used to assess COVID-19-specific changes in the care situation, negative feelings in the care situation, problems with implementation of COVID-19 measures, concerns/excessive demands, loss of support, change in informal caregivers' own involvement in care and problems with provision, comprehension & practicability of COVID-19 information, and to relate these issues to five indicators of care involvement (i.e., being the main caregiver, high expenditure of time, high level of care, dementia, no professional help). Binomial and multiple regression analyses were applied.
Results: Across indicators of care involvement, 25.5-39.7% reported that the care situation rather or greatly worsened during the COVID-19 pandemic, especially for those caring for someone with dementia or those usually relying on professional help. In a multiple regression model, the mean number of involvement indicators met was associated with age (beta = .18; CI .10-.25), excessive demands (beta = .10, CI .00-.19), problems with implementation of COVID-19 measures (beta = .11, CI .04-.19), an increase in caregiving by the informal caregivers themselves (beta = .14, CI .03-.24) as well as with no change in the amount of caregiving (beta = .18, CI .07-.29) and loss of support (beta = -.08, CI -.16-.00). No significant associations with the mean number of involvement indicators met were found for gender, educational level, change in the care situation, negative feelings, and provision, comprehension & practicability of COVID-19 information.
Conclusion: Those caregivers who perceived extensive care burden were those who suffered most during the pandemic, calling for structural support by the healthcare system now and in the future
Experimental Characterization of Cis-Acting Elements Important for Translation and Transcription in Halophilic Archaea
The basal transcription apparatus of archaea is well characterized. However, much less is known about the mechanisms of transcription termination and translation initation. Recently, experimental determination of the 5â˛-ends of ten transcripts from Pyrobaculum aerophilum revealed that these are devoid of a 5â˛-UTR. Bioinformatic analysis indicated that many transcripts of other archaeal species might also be leaderless. The 5â˛-ends and 3â˛-ends of 40 transcripts of two haloarchaeal species, Halobacterium salinarum and Haloferax volcanii, have been determined. They were used to characterize the lengths of 5â˛-UTRs and 3â˛-UTRs and to deduce consensus sequence-elements for transcription and translation. The experimental approach was complemented with a bioinformatics analysis of the H. salinarum genome sequence. Furthermore, the influence of selected 5â˛-UTRs and 3â˛-UTRs on transcript stability and translational efficiency in vivo was characterized using a newly established reporter gene system, gene fusions, and real-time PCR. Consensus sequences for basal promoter elements could be refined and a novel element was discovered. A consensus motif probably important for transcriptional termination was established. All 40 haloarchaeal transcripts analyzed had a 3â˛-UTR (average size 57 nt), and their 3â˛-ends were not posttranscriptionally modified. Experimental data and genome analyses revealed that the majority of haloarchaeal transcripts are leaderless, indicating that this is the predominant mode for translation initiation in haloarchaea. Surprisingly, the 5â˛-UTRs of most leadered transcripts did not contain a Shine-Dalgarno (SD) sequence. A genome analysis indicated that less than 10% of all genes are preceded by a SD sequence and even most proximal genes in operons lack a SD sequence. Seven different leadered transcripts devoid of a SD sequence were efficiently translated in vivo, including artificial 5â˛-UTRs of random sequences. Thus, an interaction of the 5â˛-UTRs of these leadered transcripts with the 16S rRNA could be excluded. Taken together, either a scanning mechanism similar to the mechanism of translation initiation operating in eukaryotes or a novel mechanism must operate on most leadered haloarchaeal transcripts
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Synthetic strategies to bicyclic tetraphosphanes using P1, P2 and P4 building blocks
Different reactions of Mes* substituted phosphanes (Mes* = 2,4,6-tri-tert-butylphenyl) led to the formation of the bicyclic tetraphosphane Mes*P4Mes* (5) and its unknown Lewis acid adduct 5¡GaCl3. In this context, the endoâexo isomer of 5 was fully characterized for the first time. The synthesis was achieved by reactions involving âself-assemblyâ of the P4 scaffold from P1 building blocks (i.e. primary phosphanes) or by reactions starting from P2 or P4 scaffolds (i.e. a diphosphene or cyclic tetraphosphane). Furthermore, interconversion between the exoâexo and endoâexo isomer were studied by 31P NMR spectroscopy. All compounds were fully characterized by experimental as well as computational methods
Beiträge zur Chemie der Pniktogene: Pnictanylidenphosphorane und Cyclotripnictane
Diese Arbeit beschreibt Aspekte der Chemie der Phosphanylidenphosphorane, Triphosphirane und von Mehrfachbindungssystemen der Gruppe 13 und 15. Es wird gezeigt, dass Phosphanylidenphosphorane sowohl potente Phosphiniden-Ăberträger darstellen, als auch eine Phosphiniden-artige Reaktivität zeigen. Triphosphirane mit Aryl-Substituenten kĂśnnen selektiv hergestellt werden, und deren Reaktivtät gegenĂźber Titanocen-Vorstufenkomplexen wird diskutiert. DarĂźber hinaus wird gezeigt, dass die analogen Triarsirane synthetisiert werden kĂśnnen und vielfältige Reagenzien in der MolekĂźlchemie darstellen.This thesis describes aspects of the chemistry of phosphanylidene phosphoranes, triphosphiranes and of group 13/15 multiple bond systems. It is shown that phosphanylidene phosphoranes are both potent phosphinidene transfer agents and exhibit phosphinidene-like reactivity. Triphosphiranes with aryl substituents can be selectively prepared and their reactivity towards titanocene precursor complexes is discussed. Furthermore, it is shown that the analogous triarsiranes can be synthesised and are versatile reagents in molecular chemistry
Extracorporeal Cardiac Shock Wave Therapy Ameliorates Clinical Symptoms and Improves Regional Myocardial Blood Flow in a Patient with Severe Coronary Artery Disease and Refractory Angina
Different therapeutic options are being used for chronic coronary artery disease (CAD). We report about a 51-year-old female with CAD and refractory angina pectoris despite maximally tolerated medical therapy and after both percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG). The patient received cardiac shock wave therapy (CSWT) over a period of 6 month. There was no arrhythmia during or after treatment; enzyme levels were normal at all times. PET imaging showed a substantial improvement of myocardial stress perfusion. Since the patient reported that she now was fully capable to deal with her everyday life, further treatment options were postponed. Our case report suggests that ultrasound-guided CSWT is able to improve symptoms and perfusion in ischemic myocardium
TatS: a novel in vitro tattooed human skin model for improved pigment toxicology research
Reports of tattoo-associated risks boosted the interest in tattoo pigment toxicity over the last decades. Nonetheless, the influence of tattoo pigments on skin homeostasis remains largely unknown. In vitro systems are not available to investigate the interactions between pigments and skin. Here, we established TatS, a reconstructed human full-thickness skin model with tattoo pigments incorporated into the dermis. We mixed the most frequently used tattoo pigments carbon black (0.02Â mg/ml) and titanium dioxide (TiO2, 0.4Â mg/ml) as well as the organic diazo compound Pigment Orange 13 (0.2Â mg/ml) into the dermis. Tissue viability, morphology as well as cytokine release were used to characterize TatS. Effects of tattoo pigments were compared to monolayer cultures of human fibroblasts. The tissue architecture of TatS was comparable to native human skin. The epidermal layer was fully differentiated and the keratinocytes expressed occludin, filaggrin and e-cadherin. Staining of collagen IV confirmed the formation of the basement membrane. Tenascin C was expressed in the dermal layer of fibroblasts. Although transmission electron microscopy revealed the uptake of the tattoo pigments into fibroblasts, neither viability nor cytokine secretion was altered in TatS. In contrast, TiO2 significantly decreased cell viability and increased interleukin-8 release in fibroblast monolayers. In conclusion, TatS emulates healed tattooed human skin and underlines the advantages of 3D systems over traditional 2D cell culture in tattoo pigment research. TatS is the first skin model that enables to test the effects of pigments in the dermis upon tattooing
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