| 1. |
- Davani, Hooman A., et al.
(author)
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Polarization investigation of a tunable high-speed short-wavelength bulk-micromachined MEMS-VCSEL
- 2012
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In: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. - 9780819489197 ; 8276, s. Art. no. 82760T-
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Conference paper (peer-reviewed)abstract
- We report the investigation of the state of polarization (SOP) of a tunable vertical-cavity surface-emitting laser (VCSEL) operating near 850 nm with a mode-hop free single-mode tuning range of about 12 nm and an amplitude modulation bandwidth of about 5 GHz. In addition, the effect of a sub-wavelength grating on the device and its influence on the polarization stability and polarization switching has been investigated. The VCSEL with an integrated sub-wavelength grating shows a stable SOP with a polarization mode suppression ratio (PMSR) more than 35 dB during the tuning.
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| 2. |
- Davani, Hooman A., et al.
(author)
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Widely Electro Thermal Tunable Bulk-Micromachined MEMS-VCSEL Operating Around 850nm
- 2011
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In: Conference on Lasers and Electro-Optics/Pacific Rim, CLEOPR 2011; Sydney; Australia; 28 August 2011 through 1 September 2011. - 2162-2701. - 9780977565771 ; , s. 32-34
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Conference paper (peer-reviewed)abstract
- We present the highest reported continues tuning range of 37 nm and fastest electro thermal tuning speed of 700 Hz achieved with tunable vertical-cavity surface-emitting lasers (VCSEL) and semiconductor DBRs at 850 nm wavelength range.
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| 3. |
- Davani, Hooman A., et al.
(author)
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Widely tunable high-speed bulk-micromachined short-wavelength MEMS-VCSEL
- 2010
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In: Semiconductor Laser Conference (ISLC), 2010 22nd IEEE International. - 0899-9406. - 9781424456833 ; , s. 9-10
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Conference paper (peer-reviewed)abstract
- We present the first results of a high-speed bulk-micromachined tunable vertical-cavity surface-emitting laser (VCSEL) operating near 850nm using a half-symmetric resonator with a movable curved microelectromechanical system (MEMS) membrane.
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| 4. |
- Gierl, Christian, et al.
(author)
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Tuneable VCSEL aiming for the application in interconnects and short haul systems
- 2011
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In: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. - 9780819484963 ; 7959
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Conference paper (other academic/artistic)abstract
- Widely tunable vertical cavity surface emitting lasers (VCSEL) are of high interest for optical communications, gas spectroscopy and fiber-Bragg-grating measurements. In this paper we present tunable VCSEL operating at wavelength around 850 nm and 1550 nm with tuning ranges up to 20 nm and 76 nm respectively. The first versions of VCSEL operating at 1550 nm with 76 nm tuning range and an output power of 1.3mW were not designed for high speed modulation, but for applications where only stable continious tuning is essential (e.g. gas sensing). The next step was the design of non tunable VCSEL showing high speed modulation frequencies of 10 GHz with side mode supression ratios beyond 50 dB. The latest version of these devices show record output powers of 6.7mW at 20 °C and 3mW at 80 °C. The emphasis of our present and future work lies on the combination of both technologies. The tunable VCSEL operating in the 850 nm-region reaches a modulation bandwidth of 5.5GHz with an output power of 0.8mW.
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| 5. |
- Leroux, Juliette, et al.
(author)
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Mapping the electronic transitions of protonation sites in peptides using soft X-ray action spectroscopy
- 2023
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In: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry. - 1463-9076 .- 1463-9084. ; 25:37, s. 25603-25618
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Journal article (peer-reviewed)abstract
- Near-edge X-ray absorption mass spectrometry (NEXAMS) around the nitrogen and oxygen K-edges was employed on gas-phase peptides to probe the electronic transitions related to their protonation sites, namely at basic side chains, the N-terminus and the amide oxygen. The experimental results are supported by replica exchange molecular dynamics and density-functional theory and restricted open-shell configuration with single calculations to attribute the transitions responsible for the experimentally observed resonances. We studied five tailor-made glycine-based pentapeptides, where we identified the signature of the protonation site of N-terminal proline, histidine, lysine and arginine, at 406 eV, corresponding to N 1s & RARR; & sigma;*(NHx+) (x = 2 or 3) transitions, depending on the peptides. We compared the spectra of pentaglycine and triglycine to evaluate the sensitivity of NEXAMS to protomers. Separate resonances have been identified to distinguish two protomers in triglycine, the protonation site at the N-terminus at 406 eV and the protonation site at the amide oxygen characterized by a transition at 403.1 eV.
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| 6. |
- Li, Ni L., et al.
(author)
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Genetic Predisposition to Multiple Myeloma at 5q15 Is Mediated by an ELL2 Enhancer Polymorphism
- 2017
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In: Cell Reports. - : Elsevier BV. - 2211-1247. ; 20:11, s. 2556-2564
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Journal article (peer-reviewed)abstract
- Multiple myeloma (MM) is a malignancy of plasma cells. Genome-wide association studies have shown that variation at 5q15 influences MM risk. Here, we have sought to decipher the causal variant at 5q15 and the mechanism by which it influences tumorigenesis. We show that rs6877329 G > C resides in a predicted enhancer element that physically interacts with the transcription start site of ELL2. The rs6877329-C risk allele is associated with reduced enhancer activity and lowered ELL2 expression. Since ELL2 is critical to the B cell differentiation process, reduced ELL2 expression is consistent with inherited genetic variation contributing to arrest of plasma cell development, facilitating MM clonal expansion. These data provide evidence for a biological mechanism underlying a hereditary risk of MM at 5q15.
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| 7. |
- Li, Ni, et al.
(author)
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Multiple myeloma risk variant at 7p15.3 creates an IRF4-binding site and interferes with CDCA7L expression
- 2016
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In: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 7
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Journal article (peer-reviewed)abstract
- Genome-wide association studies have identified several risk loci for multiple myeloma (MM); however, the mechanisms by which they influence MM are unknown. Here by using genetic association data and functional characterization, we demonstrate that rs4487645 G>T, the most highly associated variant (P = 5.30 × 10-25), resides in an enhancer element 47 kb upstream of the transcription start site of c-Myc-interacting CDCA7L. The G-risk allele, associated with increased CDCA7L expression (P=1.95 × 10-36), increases IRF4 binding and the enhancer interacts with the CDCA7L promoter. We show that suppression of CDCA7L limits MM proliferation through apoptosis, and increased CDCA7L expression is associated with adverse patient survival. These findings implicate IRF4-mediated CDCA7L expression in MM biology and indicate how germline variation might confer susceptibility to MM.
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| 8. |
- Rasche, Leo, et al.
(author)
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Low expression of hexokinase-2 is associated with false-negative FDG–positron emission tomography in multiple myeloma
- 2017
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In: Blood. - : American Society of Hematology. - 0006-4971 .- 1528-0020. ; 130:1, s. 30-34
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Journal article (peer-reviewed)abstract
- 18F-Fluorodeoxyglucose (FDG)–positron emission tomography (PET) and diffusion-weighted magnetic resonance imaging with background signal suppression (DWIBS) are 2 powerful functional imaging modalities in the evaluation of malignant plasma cell (PC) disease multiple myeloma (MM). Preliminary observations have suggested that MM patients with extensive disease according to DWIBS may be reported as being disease-free on FDG-PET (“PET false-negative”). The aim of this study was to describe the proportion of PET false-negativity in a representative set of 227 newly diagnosed MM patients with simultaneous assessment of FDG-PET and DWIBS, and to identify tumor-intrinsic features associated with this pattern. We found the incidence of PET false-negativity to be 11%. Neither tumor load–associated parameters, such as degree of bone marrow PC infiltration, nor the PC proliferation rate were associated with this subset. However, the gene coding for hexokinase-2, which catalyzes the first step of glycolysis, was significantly lower expressed in PET false-negative cases (5.3-fold change, P < .001) which provides a mechanistic explanation for this feature. In conclusion, we demonstrate a relevant number of patients with FDG-PET false-negative MM and a strong association between hexokinase-2 expression and this negativity: a finding which may also be relevant for clinical imaging of other hematological cancers.
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| 9. |
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