11 results on '"Graf, Urs"'
Search Results
2. Terahertz Heterodyne Array Receivers for Astronomy.
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Graf, Urs, Honingh, Cornelia, Jacobs, Karl, and Stutzki, Jürgen
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ASTRONOMY , *RECEIVING antennas , *HETERODYNE detection - Abstract
We review the development of multi-pixel heterodyne receivers for astronomical research in the submillimeter and terahertz spectral domains. We shortly address the historical development, highlighting a few pioneering instruments. A discussion of the design concepts is followed by a presentation of the technologies employed in the various receiver subsystems and of the approaches taken to optimize these for current and future instruments. [ABSTRACT FROM AUTHOR]
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- 2015
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3. Fourier Gratings as Submillimeter Beam Splitters.
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Graf, Urs U. and Heyminck, Stefan
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DIFFRACTION gratings , *BEAM splitters , *ANTENNA arrays , *SUBMILLIMETER waves - Abstract
Focuses on a study which introduced the Fourier grating as a local oscillator beam multiplexers for array receivers in the submillimeer wavelength domain. Grating structure; Manufacturing and measurements; Conclusion.
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- 2001
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4. Multidimensional fluorescence spectroscopy using a streak camera based pulse fluorometer
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Buhler, Christof A., Graf, Urs, Hochstrasser, Remo A., and Anliker, Max
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FLUORIMETER , *EMISSION spectroscopy , *OPTICAL resolution , *BIOLOGICAL specimens - Abstract
Assesses the use of streak camera based pulse fluorometer to record time-resolved emission spectra and fluorescence phenomena in biological samples. Details on the spatial resolution of the instrument; Analysis of fluorescence decay in tryptophan and tyrosine; Components of the device.
- Published
- 1998
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5. Laser free measurements of absorption and fluorescence excitation spectra in a supersonic free jet.
- Author
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Graf, Urs, Niikura, Hiromichi, and Hirayama, Satoshi
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JETS (Nuclear physics) , *ABSORPTION spectra , *FLUORESCENCE , *MEASUREMENT - Abstract
Presents an inexpensive setup for the simultaneous acquisition of both absorption and fluorescence excitation spectra in a supersonic jet. Evacuation of the vacuum chamber; Light source; Signal-to-noise ratio.
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- 1996
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6. The Spectrum of MORC2-Related Disorders: A Potential Link to Cockayne Syndrome.
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Stafki, Seth A., Turner, Johnnie, Littel, Hannah R., Bruels, Christine C., Truong, Don, Knirsch, Ursula, Stettner, Georg M., Graf, Urs, Berger, Wolfgang, Kinali, Maria, Jungbluth, Heinz, Pacak, Christina A., Hughes, Jayne, Mirchi, Amytice, Derksen, Alexa, Vincent-Delorme, Catherine, Theil, Arjan F., Bernard, Geneviève, Ellis, David, and Fassihi, Hiva
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SPINAL muscular atrophy , *DNA repair , *GENETIC testing , *CHARCOT-Marie-Tooth disease , *SYNDROMES - Abstract
Cockayne syndrome (CS) is a DNA repair disorder primarily associated with pathogenic variants in ERCC6 and ERCC8. As in other Mendelian disorders, there are a number of genetically unsolved CS cases. We ascertained five individuals with monoallelic pathogenic variants in MORC2 , previously associated with three dominantly inherited phenotypes: an axonal form of Charcot-Marie-Tooth disease type 2Z; a syndrome of developmental delay, impaired growth, dysmorphic facies, and axonal neuropathy; and a rare form of spinal muscular atrophy. One of these individuals bore a strong phenotypic resemblance to CS. We then identified monoallelic pathogenic MORC2 variants in three of five genetically unsolved individuals with a clinical diagnosis of CS. In total, we identified eight individuals with MORC2 -related disorder, four of whom had clinical features strongly suggestive of CS. Our findings indicate that some forms of MORC2 -related disorder have phenotypic similarities to CS, including features of accelerated aging. Unlike classic DNA repair disorders, MORC2- related disorder does not appear to be associated with a defect in transcription-coupled nucleotide excision repair and follows a dominant pattern of inheritance with variants typically arising de novo. Such de novo pathogenic variants present particular challenges with regard to both initial gene discovery and diagnostic evaluations. MORC2 should be included in diagnostic genetic test panels targeting the evaluation of microcephaly and/or suspected DNA repair disorders. Future studies of MORC2 and its protein product, coupled with further phenotypic characterization, will help to optimize the diagnosis, understanding, and therapy of the associated disorders. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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7. Homozygosity for a Novel DOCK7 Variant Due to Segmental Uniparental Isodisomy of Chromosome 1 Associated with Early Infantile Epileptic Encephalopathy (EIEE) and Cortical Visual Impairment.
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Kivrak Pfiffner, Fatma, Koller, Samuel, Ménétrey, Anika, Graf, Urs, Bähr, Luzy, Maspoli, Alessandro, Hackenberg, Annette, Kottke, Raimund, Gerth-Kahlert, Christina, and Berger, Wolfgang
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VISION disorders , *CHROMOSOMES , *HOMOZYGOSITY , *EPILEPSY , *GENETIC variation , *BRAIN diseases , *CHILDREN with epilepsy , *PHOTORECEPTORS - Abstract
Early infantile epileptic encephalopathy (EIEE) is a severe neurologic and neurodevelopmental disease that manifests in the first year of life. It shows a high degree of genetic heterogeneity, but the genetic origin is only identified in half of the cases. We report the case of a female child initially diagnosed with Leber congenital amaurosis (LCA), an early-onset retinal dystrophy due to photoreceptor cell degeneration in the retina. The first examination at 9 months of age revealed no reaction to light or objects and showed wandering eye movements. Ophthalmological examination did not show any ocular abnormalities. The patient displayed mildly dysmorphic features and a global developmental delay. Brain MRI demonstrated pontine hypo-/dysplasia. The patient developed myoclonic epileptic seizures and epileptic spasms with focal and generalized epileptiform discharges on electroencephalogram (EEG) at the age of 16 months. Genetic screening for a potentially pathogenic DNA sequence variant by whole-exome sequencing (WES) revealed a novel, conserved, homozygous frameshift variant (c.5391delA, p.(Ala1798LeufsTer59)) in exon 42 of the DOCK7 gene (NM_001271999.1). Further analysis by SNP array (Karyomapping) showed loss of heterozygosity (LOH) in four segments of chromosome 1. WES data of the parents and the index patient (trio analysis) demonstrated that chromosome 1 was exclusively inherited from the mother. Four LOH segments of chromosome 1 alternately showed isodisomy (UPiD) and heterodisomy (UPhD). In WES data, the father was a noncarrier, and the mother was heterozygous for this DOCK7 variant. The DOCK7 gene is located in 1p31.3, a region situated in one of the four isodisomic segments of chromosome 1, explaining the homozygosity seen in the affected child. Finally, Sanger sequencing confirmed maternal UPiD for the DOCK7 variant. Homozygous or compound heterozygous pathogenic variants in the DOCK7 (dedicator of cytokinesis 7) gene are associated with autosomal recessive, early infantile epileptic encephalopathy 23 (EIEE23; OMIM #615,859), a rare and heterogeneous group of neurodevelopmental disorders diagnosed during early childhood. To our knowledge, this is the first report of segmental uniparental iso- and heterodisomy of chromosome 1, leading to homozygosity of the DOCK7 frameshift variant in the affected patient. [ABSTRACT FROM AUTHOR]
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- 2022
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8. Bringing high spatial resolution to the far-infrared: A giant leap for astrophysics.
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Linz, Hendrik, Beuther, Henrik, Gerin, Maryvonne, Goicoechea, Javier R., Helmich, Frank, Krause, Oliver, Liu, Yao, Molinari, Sergio, Ossenkopf-Okada, Volker, Pineda, Jorge, Sauvage, Marc, Schinnerer, Eva, van der Tak, Floris, Wiedner, Martina, Amiaux, Jerome, Bhatia, Divya, Buinhas, Luisa, Durand, Gilles, Förstner, Roger, and Graf, Urs
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SPATIAL resolution , *ASTROPHYSICS , *HABITABLE planets , *ORIGIN of planets , *SPACE telescopes - Abstract
The far-infrared (FIR) regime is one of the wavelength ranges where no astronomical data with sub-arcsecond spatial resolution exist. None of the medium-term satellite projects like SPICA, Millimetron, or the Origins Space Telescope will resolve this malady. For many research areas, however, information at high spatial and spectral resolution in the FIR, taken from atomic fine-structure lines, from highly excited carbon monoxide (CO), light hydrides, and especially from water lines would open the door for transformative science. A main theme will be to trace the role of water in proto-planetary discs, to observationally advance our understanding of the planet formation process and, intimately related to that, the pathways to habitable planets and the emergence of life. Furthermore, key observations will zoom into the physics and chemistry of the star-formation process in our own Galaxy, as well as in external galaxies. The FIR provides unique tools to investigate in particular the energetics of heating, cooling, and shocks. The velocity-resolved data in these tracers will reveal the detailed dynamics engrained in these processes in a spatially resolved fashion, and will deliver the perfect synergy with ground-based molecular line data for the colder dense gas. [ABSTRACT FROM AUTHOR]
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- 2021
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9. A BOUNDARY INTEGRAL APPROACH TO THE SCATTERING FROM PERIODIC GRATINGS.
- Author
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Moore, John, Hao Ling, Graf, Urs U., and Jaffe, Daniel T.
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BOUNDARY element methods , *SCATTERING (Mathematics) , *BOUNDARY value problems , *FLOQUET theory , *ELECTRICAL harmonics - Abstract
A boundary integral formulation is presented for computing the scattering from infinite periodic gratings. Periodic boundary conditions and expansion of the fields in terms of Floquet harmonics allow the boundary integral formulation to treat just a single period of the infinite grating. Numerical results for a blazed grating designed for use at infrared wavelengths are presented and shown to be in good agreement with a series of measurements. [ABSTRACT FROM AUTHOR]
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- 1992
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10. Velocity profiles of [CII], [CI], CO, and [OI] and physical conditions in four star-forming regions in the Large Magellanic Cloud.
- Author
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Okada, Yoko, Güsten, Rolf, Requena-Torres, Miguel Angel, Röllig, Markus, Stutzki, Jürgen, Graf, Urs Ulrich, and Hughes, Annie
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VELOCITY , *INTERSTELLAR medium , *LARGE magellanic cloud , *REDSHIFT , *STAR formation - Abstract
Aims. The aim of our study is to investigate the physical properties of the star-forming interstellar medium (ISM) in the Large Magellanic Cloud (LMC) by separating the origin of the emission lines spatially and spectrally. The LMC provides a unique local template to bridge studies in the Galaxy and high redshift galaxies because of its low metallicity and proximity, enabling us to study the detailed physics of the ISM in spatially resolved individual star-forming regions. Following Okada et al. (Okada, Y., Requena-Torres, M. A., Güsten, R., et al. 2015, A&A, 580, A54), we investigate different phases of the ISM traced by carbon-bearing species in four star-forming regions in the LMC, and model the physical properties using the KOSMA-τ PDR model. Methods. We mapped 3–13 arcmin2 areas in 30 Dor, N158, N160, and N159 along the molecular ridge of the LMC in [C II] 158 μm with GREAT on board SOFIA. We also observed the same area with CO(2-1) to (6-5), 13CO(2-1) and (3-2), [C I] 3P1–3P0 and 3P2–3P1 with APEX. For selected positions in N159 and 30 Dor, we observed [O I] 145 μm and [O I] 63 μm with upGREAT. All spectra are velocity resolved. Results. In all four star-forming regions, the line profiles of CO, 13CO, and [C I] emission are similar, being reproduced by a combination of Gaussian profiles defined by CO(3-2), whereas [C II] typically shows wider line profiles or an additional velocity component. At several positions in N159 and 30 Dor, we observed the velocity-resolved [O I] 145 and 63 μm lines for the first time. At some positions, the [O I] line profiles match those of CO, at other positions they are more similar to the [C II] profiles. We interpret the different line profiles of CO, [C II] and [O I] as contributions from spatially separated clouds and/or clouds in different physical phases, which give different line ratios depending on their physical properties. We modeled the emission from the CO, [C I], [C II], and [O I] lines and the far-infrared continuum emission using the latest KOSMA-τ PDR model, which treats the dust-related physics consistently and computes the dust continuum SED together with the line emission of the chemical species. We find that the line and continuum emissions are not well-reproduced by a single clump ensemble. Toward the CO peak at N159 W, we propose a scenario that the CO, [C II], and [O I] 63 μm emission are weaker than expected because of mutual shielding among clumps. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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11. Benefits and outcomes of a new multidisciplinary approach for the management and financing of sudden unexplained death cases in a forensic setting in Switzerland.
- Author
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Neubauer, Jacqueline, Kissel, Christine K., Bolliger, Stephan A., Barbon, Daniela, Thali, Michael J., Kloiber, Daniel, Bode, Peter K., Kovacs, Boldizsar, Graf, Urs, Maspoli, Alessandro, Berger, Wolfgang, Saguner, Ardan M., and Haas, Cordula
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SUDDEN death , *CARDIAC arrest , *IMPLANTABLE cardioverter-defibrillators , *INTERDISCIPLINARY research , *FORENSIC sciences , *PILOT projects , *AUTOPSY , *GENETIC testing , *PHENOTYPES - Abstract
Sudden cardiac death (SCD) is an important public health issue. In young persons aged between 1 and 40 years, most SCDs are caused by potentially inherited cardiac diseases, often not detectable during conventional medico-legal investigations and therefore termed as sudden unexplained deaths (SUD). In this study, we describe the implementation, feasibility and importance of a standardized procedure to investigate SUD cases within the forensic framework at the Zurich Institute of Forensic Medicine in Switzerland. This new approach involves a multidisciplinary collaboration including forensic autopsy, second pathology expert opinion, post-mortem molecular genetic testing, cardiac counselling of relatives, and a tentative financing. This procedure is in line with the published Swiss and European recommendations on the management of SCDs. During a two-year pilot project, 39 sudden and unexpected death cases were collected, whereof 10 deceased remained without any identifiable cause of death after medico-legal investigation and second expert evaluation. Molecular autopsy, including 393 genes involved in cardio-vascular and metabolic diseases, identified eight pathogenic or likely pathogenic genetic variants in five out of the 10 deceased (50%). Cardio-genetic follow-up investigations in the families of the 10 deceased revealed phenotype-positive relatives in four families and required specific therapies, including an implantable cardioverter defibrillator (ICD) for primary prevention. Multidisciplinary collaboration is crucial for an optimal management of sudden unexplained death cases, to identify additional relatives at risk, and to prevent other tragic deaths within a family. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
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