1,113 research outputs found
Kalibrierung von Multi-Kamera-Systemen - Kombinierte Schätzung von intrinsischem Abbildungsverhalten der einzelnen Kameras und deren relativer Lage zueinander ohne Erfordernis sich überlappender Sichtbereiche
This thesis presents a method for the combined intrinsic and extrinsic calibration of multi camera systems including cameras with fisheye lenses and cameras with non-overlapping fields of view. A temporal movement of a calibration target consisting of a fixed arrangement of multiple checkerboard patterns is captured and used as measurement. The process of camera calibration is formulated as a full bundle adjustment
Cosmic rays in astrospheres
Cosmic rays passing through large astrospheres can be efficiently cooled
inside these "cavities" in the interstellar medium. Moreover, the energy
spectra of these energetic particles are already modulated in front of the
astrospherical bow shocks. We study the cosmic ray flux in and around lambda
Cephei as an example for an astrosphere. The large-scale plasma flow is modeled
hydrodynamically with radiative cooling. We studied the cosmic ray flux in a
stellar wind cavity using a transport model based on stochastic differential
equations. The required parameters, most importantly, the elements of the
diffusion tensor, are based on the heliospheric parameters. The magnetic field
required for the diffusion coefficients is calculated kinematically. We discuss
the transport in an astrospheric scenario with varying parameters for the
transport coefficients. We show that large stellar wind cavities can act as
sinks for the galactic cosmic ray flux and thus can give rise to small-scale
anisotropies in the direction to the observer. Small-scale cosmic ray
anisotropies can naturally be explained by the modulation of cosmic ray spectra
in huge stellar wind cavities
Multimodal data acquisition at SARS-CoV-2 drive through screening centers: Setup description and experiences in Saarland, Germany
SARS-CoV-2 drive through screening
centers (DTSC) have been implemented
worldwide as a fast and secure way of
mass screening. We use DTSCs as a platform for the acquisition of multimodal
datasets that are needed for the development of remote screening methods. Our
acquisition setup consists of an array of
thermal, infrared and RGB cameras as
well as microphones and we apply
methods from computer vision and computer audition for the contactless estimation of physiological parameters. We have recorded a multimodal dataset of
DTSC participants in Germany for the development of remote screening
methods and symptom identification. Acquisition in the early stages of a pandemic and in regions with high infection rates can facilitate and speed up the
identification of infection specific symptoms and large-scale data acquisition at
DTSC is possible without disturbing the flow of operation
Evaluation of the short form of "Experience in Close Relationships" (Revised, German Version "ECR-RD12") - A tool to measure adult attachment in primary care
Attachment theory helps us to understand patients' health behavior. Attachment styles might explain patient differences in coping behavior, self-treatment, or patient-provider relationships. In primary care time constrains are relevant. A short instrument may facilitate screening and assessment in daily medical practice. The aim of this study was to evaluate a 12-item short version of the Experience in Close Relationships-revised (ECR-R-D) to be used in primary care settings. We included 249 patients from ten general practices in central Germany into a cross-sectional study. Exploratory factor analysis was performed to evaluate the factor structure of the ECR-items. Cronbach's alpha was used to assess internal consistency. The results related to the short form of the ECR are in line with those of the German full-length version of the measure (ECR-RD 36). Internal consistencies were in an adequate range. The ECR short form can be recommended as a screening measure of attachment styles in primary care
Identification of novel inner membrane complex and apical annuli proteins of the malaria parasite Plasmodium falciparum
The inner membrane complex (IMC) is a defining feature of apicomplexan parasites, which confers stability and shape to the cell, functions as a scaffolding compartment during the formation of daughter cells and plays an important role in motility and invasion during different life cycle stages of these single-celled organisms. To explore the IMC proteome of the malaria parasite Plasmodium falciparum we applied a proximity-dependent biotin identification (BioID)-based proteomics approach, using the established IMC marker protein Photosensitized INA-Labelled protein 1 (PhIL1) as bait in asexual blood-stage parasites. Subsequent mass spectrometry-based peptide identification revealed enrichment of 12 known IMC proteins and several uncharacterized candidate proteins. We validated nine of these previously uncharacterized proteins by endogenous GFP-tagging. Six of these represent new IMC proteins, while three proteins have a distinct apical localization that most likely represents structures described as apical annuli in Toxoplasma gondii. Additionally, various Kelch13 interacting candidates were identified, suggesting an association of the Kelch13 compartment and the IMC in schizont and merozoite stages. This work extends the number of validated IMC proteins in the malaria parasite and reveals for the first time the existence of apical annuli proteins in P. falciparum. Additionally, it provides evidence for a spatial association between the Kelch13 compartment and the IMC in late blood-stage parasites
Discovery of cellular regulation by protein degradation
What follows is a story of some of the lab’s adventures mentioned above, including the inventions of new biochemical and genetic methods. This account stems, in part, from previous descriptions of the early history of the Ub field (31,32). Another antecedent is an interview I gave to Dr. Istvan Hargittai, a distinguished Hungarian chemist. It describes my life and science, including the early years in Moscow, the 1977 escape from the former Soviet Union, the essentially accidental hiring of me by MIT, and the work that ensued (33). The narrative below borrows from these sources, and mentions our more recent contributions as well
Metastable Se6 as a ligand for Ag+: from isolated molecular to polymeric 1D and 2D structures
Attempts to prepare the hitherto unknown Se6 2+ cation by the reaction of elemental selenium and Ag[A] ([A]- = [Sb(OTeF5)6]-, [Al(OC(CF3)3)4]-) in SO2 led to the formation of [(OSO)Ag(Se6)Ag(OSO)][Sb(OTeF5)6]2 1 and [(OSO)2Ag(Se6)Ag(OSO)2][Al(OC(CF3)3)4]2 2a. 1 could only be prepared by using bromine as co-oxidant, however, bulk 2b (2a with loss of SO2) was accessible from Ag[Al(OC(CF3)3)4] and grey Se in SO2 (chem. analysis). The reactions of Ag[MF6] (M= As, Sb) and elemental selenium led to crystals of 1/∞{[Ag(Se6)]∞[Ag2(SbF6)3]∞} 3 and {1/∞[Ag(Se6)Ag]∞}[AsF6]2 4. Pure bulk 4 was best prepared by the reaction of Se4[AsF6]2, silver metal and elemental selenium. Attempts to prepare bulk 1 and 3 were unsuccessful. 1–4 were characterized by single-crystal X-ray structure determinations, 2b and 4 additionally by chemical analysis and 4 also by X-ray powder diffraction, FT-Raman and FT-IR pectroscopy. Application of the PRESTO III sequence allowed for the first time 109Ag MAS NMR investigations of 4 as well as AgF, AgF2, AgMF6 and {1/∞[Ag(I2)]∞}[MF6] (M= As, Sb). Compounds 1 and 2a/b, with the very large counter ions, contain isolated [Ag(Se6)Ag]2+ heterocubane units consisting of a Se6 molecule bicapped by two silver cations (local D3d sym). 3 and 4, with the smaller anions, contain close packed stacked arrays of Se6 rings with Ag+ residing in octahedral holes. Each Ag+ ion coordinates to three selenium atoms of each adjacent Se6 ring. 4 contains [Ag(Se6)+]∞ stacks additionally linked by Ag(2)+ into a two dimensional network. 3 features a remarkable 3-dimensional [Ag2(SbF6)3]- anion held together by strong Sb–F … Ag contacts between the component Ag+ and [SbF6]- ions. The hexagonal channels formed by the [Ag2(SbF6)3]- anions are filled by stacks of [Ag(Se6)+]∞ cations. Overall 1–4 are new members of the rare class of metal complexes of neutral main group elemental clusters, in which the main group element is positively polarized due to coordination to a metal ion. Notably, 1 to 4 include the commonly metastable Se6 molecule as a ligand. The structure, bonding and thermodynamics of 1 to 4 were investigated with the help of quantum chemical calculations (PBE0/TZVPP and (RI-)MP2/TZVPP, in part including COSMO solvation) and Born–Fajans–Haber-cycle calculations. From an analysis of all the available data it appears that the formation of the usually metastable Se6 molecule from grey selenium is thermodynamically driven by the coordination to the Ag+ ions
CD95 co-stimulation blocks activation of naive T cells by inhibiting T cell receptor signaling
CD95 is a multifunctional receptor that induces cell death or proliferation depending on the signal, cell type, and cellular context. Here, we describe a thus far unknown function of CD95 as a silencer of T cell activation. Naive human T cells triggered by antigen-presenting cells expressing a membrane-bound form of CD95 ligand (CD95L) or stimulated by anti-CD3 and -CD28 antibodies in the presence of recombinant CD95L had reduced activation and proliferation, whereas preactivated, CD95-sensitive T cells underwent apoptosis. Triggering of CD95 during T cell priming interfered with proximal T cell receptor signaling by inhibiting the recruitment of ζ-chain–associated protein of 70 kD, phospholipase-γ, and protein kinase C-θ into lipid rafts, thereby preventing their mutual tyrosine protein phosphorylation. Subsequently, Ca2+ mobilization and nuclear translocation of transcription factors NFAT, AP1, and NF-κB were strongly reduced, leading to impaired cytokine secretion. CD95-mediated inhibition of proliferation in naive T cells could not be reverted by the addition of exogenous interleukin-2 and T cells primed by CD95 co-stimulation remained partially unresponsive upon secondary T cell stimulation. HIV infection induced CD95L expression in primary human antigeen-presenting cells, and thereby suppressed T cell activation, suggesting that CD95/CD95L-mediated silencing of T cell activation represents a novel mechanism of immune evasion
Precision cluster mass determination from weak lensing
Weak gravitational lensing has been used extensively in the past decade to
constrain the masses of galaxy clusters, and is the most promising
observational technique for providing the mass calibration necessary for
precision cosmology with clusters. There are several challenges in estimating
cluster masses, particularly (a) the sensitivity to astrophysical effects and
observational systematics that modify the signal relative to the theoretical
expectations, and (b) biases that can arise due to assumptions in the mass
estimation method, such as the assumed radial profile of the cluster. All of
these challenges are more problematic in the inner regions of the cluster,
suggesting that their influence would ideally be suppressed for the purpose of
mass estimation. However, at any given radius the differential surface density
measured by lensing is sensitive to all mass within that radius, and the
corrupted signal from the inner parts is spread out to all scales. We develop a
new statistic that is ideal for estimation of cluster masses because it
completely eliminates mass contributions below a chosen scale (which we suggest
should be about 20 per cent of the virial radius), and thus reduces sensitivity
to systematic and astrophysical effects. We use simulated and analytical
profiles to quantify systematic biases on the estimated masses for several
standard methods of mass estimation, finding that these can lead to significant
mass biases that range from ten to over fifty per cent. The mass uncertainties
when using our new statistic are reduced by up to a factor of ten relative to
the standard methods, while only moderately increasing the statistical errors.
This new method of mass estimation will enable a higher level of precision in
future science work with weak lensing mass estimates for galaxy clusters.Comment: 27 pages, 7 figures, submitted to MNRAS; v2 has expanded explanation
for clarity, no change in results or conclusion
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