Traveling wave method for simulating geometric beam coupling impedance of a beamscreen with pumping holes

In particle accelerators, pumping holes in a vacuum chamber can be a source of unwanted broadband coupling impedance, leading to beam instabilities. Analytical methods have been previously developed to estimate the impedance of holes in circular-like chambers e.g. the beamscreen of the Large Hadron Collider (LHC). More sophisticated chamber designs like that of the High Energy LHC (HE-LHC) and the Future Circular Collider (FCC-hh) call for a different way to calculate the impedance. We propose using decomposition of the wakefield into synchronous traveling waves and employing a numerical solver to find the impedance of each wave. This method is compared to the direct time domain wakefield calculation method and its greater sensitivity to small impedances is shown

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Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively

Single-molecule analysis of dynamics and interactions of the SecYEG translocon

Protein translocation and insertion into the bacterial cytoplasmic membrane are the essential processes mediated by the Sec machinery. The core machinery is composed of the membrane-embedded translocon SecYEG that interacts with the secretion-dedicated ATPase SecA and translating ribosomes. Despite the simplicity and the available structural insights on the system, diverse molecular mechanisms and functional dynamics have been proposed. Here, we employ total internal reflection fluorescence microscopy to study the oligomeric state and diffusion of SecYEG translocons in supported lipid bilayers at the single-molecule level. Silane-based coating ensured the mobility of lipids and reconstituted translocons within the bilayer. Brightness analysis suggested that approx. 70% of the translocons were monomeric. The translocons remained in a monomeric form upon ribosome binding, but partial oligomerization occurred in the presence of nucleotide-free SecA. Individual trajectories of SecYEG in the lipid bilayer revealed dynamic heterogeneity of diffusion, as translocons commonly switched between slow and fast mobility modes with corresponding diffusion coefficients of 0.03 and 0.7 µm2·s−1. Interactions with SecA ATPase had a minor effect on the lateral mobility, while bound ribosome:nascent chain complexes substantially hindered the diffusion of single translocons. Notably, the mobility of the translocon:ribosome complexes was not affected by the solvent viscosity or macromolecular crowding modulated by Ficoll PM 70, so it was largely determined by interactions within the lipid bilayer and at the interface. We suggest that the complex mobility of SecYEG arises from the conformational dynamics of the translocon and protein:lipid interactions

Longitudinal phase space reconstruction simulation studies using a novel X-band transverse deflecting structure at the SINBAD facility at DESY

A transverse deflecting structure (TDS) is a well-known device for characterizing the longitudinal properties of an electron bunch in a linear accelerator. The standard use of such a cavity involves streaking the bunch along a transverse axis and analysing the image on a screen downstream to find the bunch length and slice properties along the other transverse axis. A novel X-band deflecting structure, which will allow the polarization of the deflecting field to be adjusted, is currently being designed as part of a collaboration between CERN, DESY and PSI. This new design will allow bunches to be streaked at any transverse angle within the cavity, which will open up the possibility of new measurement techniques, which could be combined to characterize the 6D phase space distribution of bunches. In this paper, a method is presented for reconstructing the longitudinal phase space distribution of bunches by using the TDS in combination with a dipole. Simulations of this technique for the SINBAD-ARES beamline are presented and the key limitations related to temporal resolution and induced energy spread are discussed.Comment: 6 page

Study of wettability and solderability of SiC ceramics with Ni by use of Sn-Sb-Ti solder by heating with electron beam in vacuum

The aim of this research was to study the wettability and solderability of SiC ceramics by the use of an active solder of the type Sn5Sb3Ti in a vacuum by electron beam heating. This solder exerts a narrow melting interval, and only one thermal effect, a peritectic reaction, was observed. The liquidus temperature of the solder is approximately 243 degrees C. The solder consists of a tin matrix where the Ti-6(Sb,Sn)(5) and TiSbSn phases are precipitated. The solder wettability on a SiC substrate decreases with decreasing soldering temperature. The best wetting angle of 33 degrees was obtained in a vacuum at the temperature of 950 degrees C. The bond between the SiC ceramics and the solder was formed due to the interaction of Ti and Ni with silicon contained in the SiC ceramics. The formation of new TiSi2 and Ti3Ni5Si6 phases, which form the reaction layer and thus ensure the bond formation, was observed. The bond with Ni is formed due to the solubility of Ni in the tin solder. Two phases, namely the Ni3Sn2 and Ni3Sn phases, were identified in the transition zone of the Ni/Sn5Sb3Ti joint. The highest shear strength, around 40 MPa, was attained at the soldering temperature of 850 degrees C.Web of Science1515art. no. 530

Colorectal Cancer with Residual Polyp of Origin: A Model of Malignant Transformation

AbstractThe majority of colorectal cancers (CRCs) arise from adenomatous polyps. In this study, we sought to present the underrecognized CRC with the residual polyp of origin (CRC RPO+) as an entity to be utilized as a model to study colorectal carcinogenesis. We identified all subjects with biopsy-proven CRC RPO+ that were evaluated over 10 years at Mayo Clinic, Rochester, MN, and compared their clinical and pathologic characteristics to CRC without remnant polyps (CRC RPO−). Overall survival and disease-free survival overlap with an equivalent hazard ratio between CRC RPO+ and RPO− cases when age, stage, and grade are adjusted. The somatic genomic profile obtained by whole genome sequencing and the gene expression profiles by RNA-seq for CRC RPO+ tumors were compared with that of age -and gender-matched CRC RPO− evaluated by The Cancer Genome Atlas. CRC RPO+ cases were more commonly found with lower-grade, earlier-stage disease than CRC RPO−. However, within the same disease stage and grade, their clinical course is very similar to that of CRC RPO−. The mutation frequencies of commonly mutated genes in CRC are similar between CRC RPO+ and RPO− cases. Likewise, gene expression patterns are indistinguishable between the RPO+ and RPO− cases. We have confirmed that CRC RPO+ is clinically and biologically similar to CRC RPO− and may be utilized as a model of the adenoma to carcinoma transition

A simple approach for detecting HLA-A02 alleles in archival formalin-fixed paraffin-embedded tissue samples and an application example for studying cancer immunoediting

The HLA system represents a central component of the antigen presentation machinery. As every patient possesses a defined set of HLA molecules, only certain antigens can be presented on the cell surface. Thus, studying HLA type-dependent antigen presentation can improve the understanding of variation in susceptibility to various diseases, including infectious diseases and cancer. In archival formalin-fixed paraffin-embedded (FFPE) tissue, the HLA type is difficult to analyze because of fragmentation of DNA, hindering the application of commonly used assays that rely on long DNA stretches. Addressing these difficulties, we present a refined approach for characterizing presence or absence of HLA-A*02, the most common HLA-A allele in the Caucasian population, in archival samples. We validated our genotyping strategy in a cohort of 90 samples with HLA status obtained by an NGS-based method. 90% (n = 81) of the samples could be analyzed with the approach. For all of them, the presence or absence of HLA-A*02 alleles was correctly determined with the method, demonstrating 100% sensitivity and specificity (95% CI: 91.40%-100% and 91.19%-100%). Furthermore, we provide an example of application in an independent cohort of 73 FFPE microsatellite-unstable (MSI) colorectal cancer samples. As MSI cancer cells encompass a high number of mutations in coding microsatellites, leading to the generation of highly immunogenic frameshift peptide antigens, they are ideally suited for studying relations between the mutational landscape of tumor cells and interindividual differences in the immune system, including the HLA genotype. Overall, our method can help to promote studying HLA type-dependency during the pathogenesis of a wide range of diseases, making archival and historic tissue samples accessible for identifying HLA-A*02 alleles.Peer reviewe

Comparative transcriptome and gene regulation in human iPSC-derived organoids and donor-identical brain tissue

Modeling human brain development in vitro is critically important to understand the pathophysiology of neuropsychiatric disorders. As part of the PsychENCODE project, we generated human induced pluripotent stem cells (hiPSCs) from skin fibroblasts of three human specimens at 15, 16 and 17 postconceptional weeks. These hiPSC were differentiated into telencephalic organoids to study early genetic programs in forebrain development. By using RNA-seq and histone chromatin immunoprecipitation (ChIP-seq), we compared transcriptomes and epigenomes of hiPSCs-derived organoids to donor-identical cortical brain tissue. Immunocytochemical characterization of the organoids over a time course (TD0, TD11 and TD30) showed expression of radial glial markers and mature cortical neurons confirming telencephalic fate. Hierarchical clustering of the organoids’ transcriptomes demonstrated stage-specific patterns of gene expression during in vitro development. Mapping organoids’ transcriptomes against the BrainSpan dataset suggested highest correlations with neocortex and showed their correspondence to post-conceptional weeks 8-16 of human fetal development. We then inferred transcriptional alterations, by differential gene expression, between organoids and the two brain regions analyzed. We found ~5000 of differentially expressed genes (DEG) between TD0 and fetal cortex and a decreasing number of DEG at TD11 and TD30 suggesting a stronger, albeit incomplete similarity of the organoids to the cortex at later time points. ChIP-seq experiments identified H3K27ac and H3K4me3 peaks (putative promoters and enhancers) differentially active at different organoids developmental stages and between organoids and fetal brain. Overall, however, hierarchical clustering of H3K27ac and H3K4me3 peaks demonstrated clustering of organoids with human fetal brain samples from various databases, whereas neonatal and adult brain samples formed separate clusters. These data suggest that organoids recapitulate in part transcriptome and epigenome features of fetal human brain

Flexomagnetism and vertically graded Néel temperature of antiferromagnetic Cr2O3 thin films

Antiferromagnetic insulators are a prospective materials platform for magnonics, spin superfluidity, THz spintronics, and non-volatile data storage. A magnetomechanical coupling in antiferromagnets offers vast advantages in the control and manipulation of the primary order parameter yet remains largely unexplored. Here, we discover a new member in the family of flexoeffects in thin films of Cr2O3. We demonstrate that a gradient of mechanical strain can impact the magnetic phase transition resulting in the distribution of the Néel temperature along the thickness of a 50-nm-thick film. The inhomogeneous reduction of the antiferromagnetic order parameter induces a flexomagnetic coefficient of about 15 μB nm−2. The antiferromagnetic ordering in the inhomogeneously strained films can persist up to 100 °C, rendering Cr2O3 relevant for industrial electronics applications. Strain gradient in Cr2O3 thin films enables fundamental research on magnetomechanics and thermodynamics of antiferromagnetic solitons, spin waves and artificial spin ice systems in magnetic materials with continuously graded parameters

FUmanoid team description 2009

Abstract. This document describes hardware and software of the robots developed by the "FUmanoid" Team for the RoboCup competitions to be held in Graz, Austria 2009. The robot has 22 actuated degrees of freedom based on Dynamixel RX28, and RX64 servos. Central Processing, including Machine vision, Planning and control is performed using a Gumstix Verdex 6LP which is an ARM based 600MHz platform. Planning algorithms are organized in a new structure called Concurrent Scenario based Planning (CSBP). This paper explains the software and hardware used for the robot as well as control and stabilization methods developed by our team