NobleBlocks

Texas Instruments (Switzerland)

companyDietikon, Switzerland

Research output, citation impact, and the most-cited recent papers from Texas Instruments (Switzerland) (Switzerland). Aggregated across the NobleBlocks index of 300M+ scholarly works.

Total works
107
Citations
9.3K
h-index
20
i10-index
44
Also known as
Texas Instruments (Switzerland)

Top-cited papers from Texas Instruments (Switzerland)

The IntCal20 Northern Hemisphere Radiocarbon Age Calibration Curve (0–55 cal kBP)
Paula Reimer, William E. N. Austin, Édouard Bard, Alex Bayliss +4 more
2020· Radiocarbon7.5Kdoi:10.1017/rdc.2020.41

ABSTRACT Radiocarbon ( 14 C) ages cannot provide absolutely dated chronologies for archaeological or paleoenvironmental studies directly but must be converted to calendar age equivalents using a calibration curve compensating for fluctuations in atmospheric 14 C concentration. Although calibration curves are constructed from independently dated archives, they invariably require revision as new data become available and our understanding of the Earth system improves. In this volume the international 14 C calibration curves for both the Northern and Southern Hemispheres, as well as for the ocean surface layer, have been updated to include a wealth of new data and extended to 55,000 cal BP. Based on tree rings, IntCal20 now extends as a fully atmospheric record to ca. 13,900 cal BP. For the older part of the timescale, IntCal20 comprises statistically integrated evidence from floating tree-ring chronologies, lacustrine and marine sediments, speleothems, and corals. We utilized improved evaluation of the timescales and location variable 14 C offsets from the atmosphere (reservoir age, dead carbon fraction) for each dataset. New statistical methods have refined the structure of the calibration curves while maintaining a robust treatment of uncertainties in the 14 C ages, the calendar ages and other corrections. The inclusion of modeled marine reservoir ages derived from a three-dimensional ocean circulation model has allowed us to apply more appropriate reservoir corrections to the marine 14 C data rather than the previous use of constant regional offsets from the atmosphere. Here we provide an overview of the new and revised datasets and the associated methods used for the construction of the IntCal20 curve and explore potential regional offsets for tree-ring data. We discuss the main differences with respect to the previous calibration curve, IntCal13, and some of the implications for archaeology and geosciences ranging from the recent past to the time of the extinction of the Neanderthals.

Forest resilience to drought varies across biomes
Antonio Gazol, J. Julio Camarero, Sergio M. Vicente‐Serrano, Raúl Sánchez‐Salguero +4 more
2018· Global Change Biology470doi:10.1111/gcb.14082

Forecasted increase drought frequency and severity may drive worldwide declines in forest productivity. Species-level responses to a drier world are likely to be influenced by their functional traits. Here, we analyse forest resilience to drought using an extensive network of tree-ring width data and satellite imagery. We compiled proxies of forest growth and productivity (TRWi, absolutely dated ring-width indices; NDVI, Normalized Difference Vegetation Index) for 11 tree species and 502 forests in Spain corresponding to Mediterranean, temperate, and continental biomes. Four different components of forest resilience to drought were calculated based on TRWi and NDVI data before, during, and after four major droughts (1986, 1994-1995, 1999, and 2005), and pointed out that TRWi data were more sensitive metrics of forest resilience to drought than NDVI data. Resilience was related to both drought severity and forest composition. Evergreen gymnosperms dominating semi-arid Mediterranean forests showed the lowest resistance to drought, but higher recovery than deciduous angiosperms dominating humid temperate forests. Moreover, semi-arid gymnosperm forests presented a negative temporal trend in the resistance to drought, but this pattern was absent in continental and temperate forests. Although gymnosperms in dry Mediterranean forests showed a faster recovery after drought, their recovery potential could be constrained if droughts become more frequent. Conversely, angiosperms and gymnosperms inhabiting temperate and continental sites might have problems to recover after more intense droughts since they resist drought but are less able to recover afterwards.

Drought legacies are short, prevail in dry conifer forests and depend on growth variability
Antonio Gazol, J. Julio Camarero, Raúl Sánchez‐Salguero, Sergio M. Vicente‐Serrano +4 more
2020· Journal of Ecology123doi:10.1111/1365-2745.13435

Abstract The negative impacts of drought on forest growth and productivity last for several years generating legacies, although the factors that determine why such legacies vary across sites and tree species remain unclear. We used an extensive network of tree‐ring width (RWI, ring‐width index) records of 16 tree species from 567 forests, and high‐resolution climate and normalized difference vegetation index (NDVI) datasets across Spain during the common period 1982‒2008 to test the hypothesis that climate conditions and growth features modulate legacy effects of drought on forests. Legacy effects of drought were calculated as the differences between detrended‐only RWI and NDVI series (i.e. after removing long‐term growth trends) and pre‐whitened RWI and NDVI series predicted by a model including drought intensity. Superposed Epoch Analysis (SEA) was used to estimate whether legacy effects differed from random. Finally, legacy effects were related to water balance, growth persistence and variability, and tree species identity. We found a widespread occurrence of drought legacy effects on both RWI and NDVI, but they were seldom significant. According to SEA, first‐year drought legacies were negative and different from random in 9% and 5% of the RWI and NDVI series respectively. The number of significant second‐ and third‐year legacies was substantially lower. Differences between RWI and NDVI legacies indicate that canopy greenness and radial growth responses to drought are decoupled. We found variations in legacies between tree species with gymnosperms presenting larger first‐year drought legacies than angiosperms, which were exposed to less severe droughts. Greater growth variability can explain the presence of first‐year RWI legacies in gymnosperms from dry sites despite that the relationship between growth variability and legacies was complex. Synthesis . Accounting for species and site responses to drought provides a better understanding of the magnitude and duration of drought legacies on forest growth and productivity. Despite the widespread occurrence of growth reductions in the years during and after drought occurrence, significant legacies were not very common, mostly lasted one year, and were more widespread in gymnosperms. These are relevant factors to be considered in the future when studying the consequences of drought on forest productivity and tree growth.

Online <sup>13</sup>C and <sup>14</sup>C Gas Measurements by EA-IRMS–AMS at ETH Zürich
Cameron McIntyre, Lukas Wacker, Negar Haghipour, Thomas M. Blattmann +4 more
2016· Radiocarbon94doi:10.1017/rdc.2016.68

Abstract Studies using carbon isotopes to understand the global carbon cycle are critical to identify and quantify sources, sinks, and processes and how humans may impact them. 13 C and 14 C are routinely measured individually; however, there is a need to develop instrumentation that can perform concurrent online analyses that can generate rich data sets conveniently and efficiently. To satisfy these requirements, we coupled an elemental analyzer to a stable isotope mass spectrometer and an accelerator mass spectrometer system fitted with a gas ion source. We first tested the system with standard materials and then reanalyzed a sediment core from the Bay of Bengal that had been analyzed for 14 C by conventional methods. The system was able to produce %C, 13 C, and 14 C data that were accurate and precise, and suitable for the purposes of our biogeochemistry group. The system was compact and convenient and is appropriate for use in a range of fields of research.

Somatic mosaicism and common genetic variation contribute to the risk of very-early-onset inflammatory bowel disease
Eva Serra, Tobias Schwerd, Loukas Moutsianas, Athena Cavounidis +4 more
2020· Nature Communications64doi:10.1038/s41467-019-14275-y

Abstract Very-early-onset inflammatory bowel disease (VEO-IBD) is a heterogeneous phenotype associated with a spectrum of rare Mendelian disorders. Here, we perform whole-exome-sequencing and genome-wide genotyping in 145 patients (median age-at-diagnosis of 3.5 years), in whom no Mendelian disorders were clinically suspected. In five patients we detect a primary immunodeficiency or enteropathy, with clinical consequences ( XIAP, CYBA, SH2D1A, PCSK1 ). We also present a case study of a VEO-IBD patient with a mosaic de novo, pathogenic allele in CYBB . The mutation is present in ~70% of phagocytes and sufficient to result in defective bacterial handling but not life-threatening infections. Finally, we show that VEO-IBD patients have, on average, higher IBD polygenic risk scores than population controls (99 patients and 18,780 controls; P &lt; 4 × 10 −10 ), and replicate this finding in an independent cohort of VEO-IBD cases and controls (117 patients and 2,603 controls; P &lt; 5 × 10 −10 ). This discovery indicates that a polygenic component operates in VEO-IBD pathogenesis.

Development and analytic validation of a radioimmunoassay for the quantification of canine calprotectin in serum and feces from dogs
Romy M. Heilmann, Jan S. Suchodolski, Jörg M. Steiner
2008· American Journal of Veterinary Research63doi:10.2460/ajvr.69.7.845

OBJECTIVE: To develop and analytically validate a radioimmunoassay (RIA) for the quantification of canine calprotectin (cCP) in serum and fecal extracts of dogs. Sample Population-Serum samples (n = 50) and fecal samples (30) were obtained from healthy dogs of various breeds and ages. PROCEDURES: A competitive, liquid-phase, double-antibody RIA was developed and analytically validated by assessing analytic sensitivity, working range, linearity, accuracy, precision, and reproducibility. Reference intervals for serum and fecal cCP concentrations were determined. RESULTS: Sensitivity and upper limit of the working range were 29 and 12,774 microg/L for serum and 2.9 and 1,277.4 microg/g for fecal extracts, respectively. Observed-to-expected ratios for serial dilutions of 6 serum samples and 6 fecal extracts ranged from 95.3% to 138.2% and from 80.9% to 118.1%, respectively. Observed-to-expected ratios for spiking recovery for 6 serum samples and 6 fecal extracts ranged from 84.6% to 121.5% and from 80.3% to 132.1%, respectively. Coefficients of variation for intra-assay and interassay variability were < 3.9% and < 8.7% for 6 serum samples and < 8.5% and < 12.6% for 6 fecal extracts, respectively. Reference intervals were 92 to 1,121 microg of cCP/L for serum and < 2.9 to 137.5 microg of cCP/g for fecal extracts. CONCLUSIONS AND CLINICAL RELEVANCE: The RIA described here was analytically sensitive, linear, accurate, precise, and reproducible for the quantification of cCP in serum and fecal extracts. This assay should facilitate research into the clinical use of serum and fecal cCP measurements in dogs with inflammatory bowel disease.

Comparison of commercially available ELISA kits with human sera-based detection methods for peanut allergens in foods
Patricia E. Koch, G. F. Schäppi, Roland Poms, B. Wüthrich +2 more
2003· Food Additives & Contaminants48doi:10.1080/02652030310001594469

Undeclared peanut allergens as contaminants in foodstuffs represent a major health problem for sensitized persons. Various immunochemical techniques are employed to detect and quantify peanut allergens. There is an urgent need to compare and standardize those test systems to enable comparable allergen analyses of foodstuffs, comparable studies, and consequent and consistent measures against the presence of hidden peanut allergens. The present study compared commercially available peanut ELISA kits with human sera-based immunoassay techniques (dot blotting and Western blotting), enabling semiquantitative and quantitative detection, and identification of peanut contaminants in foodstuffs. Additionally, the effect of conventional roasting conditions on the detection and quantification of peanut with the selected methods was investigated.

Galaxy power spectrum in general relativity
Nastassia Grimm, Fulvio Scaccabarozzi, Jaiyul Yoo, Sang Gyu Biern +1 more
2020· Journal of Cosmology and Astroparticle Physics33doi:10.1088/1475-7516/2020/11/064

We present the galaxy power spectrum in general relativity. Using a novel approach, we derive the galaxy power spectrum taking into account all the relativistic effects in observations. In particular, we show independently of survey geometry that relativistic effects yield no divergent terms (proportional to $k^{-4}P_m(k)$ or $k^{-2}P_m(k)$ on all scales) that would mimic the signal of primordial non-Gaussianity. This cancellation of such divergent terms is indeed expected from the equivalence principle, meaning that any perturbation acting as a uniform gravity on the scale of the experiment cannot be measured. We find that the unphysical infrared divergence obtained in previous calculations occurred only due to not considering all general relativistic contributions consistently. Despite the absence of divergent terms, general relativistic effects represented by non-divergent terms alter the galaxy power spectrum at large scales (smaller than the horizon scale). In our numerical computation of the full galaxy power spectrum, we show the deviations from the standard redshift-space power spectrum due to these non-divergent corrections. We conclude that, as relativistic effects significantly alter the galaxy power spectrum at $k\lesssim k_{eq}$, they need to be taken into account in the analysis of large-scale data.

Galaxy two-point correlation function in general relativity
Fulvio Scaccabarozzi, Jaiyul Yoo, Sang Gyu Biern
2018· Journal of Cosmology and Astroparticle Physics32doi:10.1088/1475-7516/2018/10/024

We perform theoretical and numerical studies of the full relativistic two-point galaxy correlation function, considering the linear-order scalar and tensor perturbation contributions and the wide-angle effects. Using the gauge-invariant relativistic description of galaxy clustering and accounting for the contributions at the observer position, we demonstrate that the complete theoretical expression is devoid of any long-mode contributions from scalar or tensor perturbations and it lacks the infrared divergences in agreement with the equivalence principle. By showing that the gravitational potential contribution to the correlation function converges in the infrared, our study justifies an IR cut-off $(k_{\text{IR}} \leq H_0)$ in computing the gravitational potential contribution. Using the full gauge-invariant expression, we numerically compute the galaxy two-point correlation function and study the individual contributions in the conformal Newtonian gauge. We find that the terms at the observer position such as the coordinate lapses and the observer velocity (missing in the standard formalism) dominate over the other relativistic contributions in the conformal Newtonian gauge such as the source velocity, the gravitational potential, the integrated Sachs-Wolf effect, the Shapiro time-delay and the lensing convergence. Compared to the standard Newtonian theoretical predictions that consider only the density fluctuation and redshift-space distortions, the relativistic effects in galaxy clustering result in a few percent-level systematic errors beyond the scale of the baryonic acoustic oscillation. Our theoretical and numerical study provides a comprehensive understanding of the relativistic effects in the galaxy two-point correlation function, as it proves the validity of the theoretical prediction and accounts for effects that are often neglected in its numerical evaluation.

Tree growth response to drought partially explains regional‐scale growth and mortality patterns in Iberian forests
Antonio Gazol, J. Julio Camarero, Raúl Sánchez‐Salguero, Miguel Á. Zavala +4 more
2022· Ecological Applications29doi:10.1002/eap.2589

Tree-ring data has been widely used to inform about tree growth responses to drought at the individual scale, but less is known about how tree growth sensitivity to drought scales up driving changes in forest dynamics. Here, we related tree-ring growth chronologies and stand-level forest changes in basal area from two independent data sets to test if tree-ring responses to drought match stand forest dynamics (stand basal area growth, ingrowth, and mortality). We assessed if tree growth and changes in forest basal area covary as a function of spatial scale and tree taxa (gymnosperm or angiosperm). To this end, we compared a tree-ring network with stand data from the Spanish National Forest Inventory. We focused on the cumulative impact of drought on tree growth and demography in the period 1981-2005. Drought years were identified by the Standardized Precipitation Evapotranspiration Index, and their impacts on tree growth by quantifying tree-ring width reductions. We hypothesized that forests with greater drought impacts on tree growth will also show reduced stand basal area growth and ingrowth and enhanced mortality. This is expected to occur in forests dominated by gymnosperms on drought-prone regions. Cumulative growth reductions during dry years were higher in forests dominated by gymnosperms and presented a greater magnitude and spatial autocorrelation than for angiosperms. Cumulative drought-induced tree growth reductions and changes in forest basal area were related, but initial stand density and basal area were the main factors driving changes in basal area. In drought-prone gymnosperm forests, we observed that sites with greater growth reductions had lower stand basal area growth and greater mortality. Consequently, stand basal area, forest growth, and ingrowth in regions with large drought impacts was significantly lower than in regions less impacted by drought. Tree growth sensitivity to drought can be used as a predictor of gymnosperm demographic rates in terms of stand basal area growth and ingrowth at regional scales, but further studies may try to disentangle how initial stand density modulates such relationships. Drought-induced growth reductions and their cumulative impacts have strong potential to be used as early-warning indicators of regional forest vulnerability.

Loss of the branched-chain amino acid transporter CD98hc alters the development of colonic macrophages in mice
Philipp Wuggenig, Berna Kaya, Hassan Melhem, C. Korcan Ayata +4 more
2020· Communications Biology27doi:10.1038/s42003-020-0842-3

Abstract Comprehensive development is critical for gut macrophages being essential for the intestinal immune system. However, the underlying mechanisms of macrophage development in the colon remain elusive. To investigate the function of branched-chain amino acids in the development of gut macrophages, an inducible knock-out mouse model for the branched-chain amino acid transporter CD98hc in CX3CR1 + macrophages was generated. The relatively selective deletion of CD98hc in macrophage populations leads to attenuated severity of chemically-induced colitis that we assessed by clinical, endoscopic, and histological scoring. Single-cell RNA sequencing of colonic lamina propria macrophages revealed that conditional deletion of CD98hc alters the “monocyte waterfall”-development to MHC II + macrophages. The change in the macrophage development after deletion of CD98hc is associated with increased apoptotic gene expression. Our results show that CD98hc deletion changes the development of colonic macrophages.

Non-linear general relativistic effects in the observed redshift
Giuseppe Fanizza, Jaiyul Yoo, Sang Gyu Biern
2018· Journal of Cosmology and Astroparticle Physics24doi:10.1088/1475-7516/2018/09/037

We present the second-order expression for the observed redshift, accounting for all the relativistic effects from the light propagation and from the frame change at the observer and the source positions. We derive the generic gauge-transformation law that any observable quantities should satisfy, and we verify our second-order expression for the observed redshift by explicitly checking its gauge transformation property. This is the first time an explicit verification is made for the second-order calculations of observable quantities. We present our results in popular gauge choices for easy use and discuss the origin of disagreements in previous calculations.

Speckle Reduction by Optimized Multimode Fiber Combined With Dielectric Elastomer Actuator and Lightpipe Homogenizer
Qianli Ma, Chanqing Xu, Adrian Kitai, David Stadler
2016· Journal of Display Technology23doi:10.1109/jdt.2016.2568458

Speckle, due to the interference of coherent light having random phases, can seriously degrade image quality in a laser based projection system. The speckle is even worse when the diode pumped solid state (DPSS) lasers are used as light sources since the laser linewidth from the DPSS lasers is usually very narrow. In this paper, a de-speckle system consisting of a multimode fiber (MMF), a dielectric elastomer actuator (DEA) and a lightpipe is proposed and demonstrated, which can reduce speckle significantly. The speckle reduction components used in the system are optimized, taking into account speckle reduction ability and optical efficiency. The proposed de-speckle system is low in cost and easy to set up. It features a low optical power penalty and is compatible with large venue laser projection for applications such as digital cinema. In the proposed de-speckle system, test images captured by a camera with a setup following the recently proposed speckle measurement standard can achieve a speckle contrast ratio as low as 4.7%. By adding a voice coil motor (VCM) to vibrate the MMF to generate temporal diversity, the speckle contrast ratio can be further reduced to 3.7%.

Waveform Inversion of Crosshole Georadar Data: Influence of Source Wavelet Variability and the Suitability of a Single Wavelet Assumption
Florian Belina, James Irving, Jacques R. Ernst, Klaus Holliger
2012· IEEE Transactions on Geoscience and Remote Sensing21doi:10.1109/tgrs.2012.2194154

Waveform-based tomographic imaging of crosshole georadar data is a powerful method to investigate the shallow subsurface because of its ability to provide images of electrical properties in near-surface environments with unprecedented spatial resolution. A critical issue with waveform inversion is the a priori unknown source signal. Indeed, the estimation of the source pulse is notoriously difficult but essential for the effective application of this method. Here, we explore the viability and robustness of a recently proposed deconvolution-based procedure to estimate the source pulse during waveform inversion of crosshole georadar data, where changes in wavelet shape with location as a result of varying near-field conditions and differences in antenna coupling may be significant. Specifically, we examine whether a single, average estimated source current function can adequately represent the pulses radiated at all transmitter locations during a crosshole georadar survey, or whether a separate source wavelet estimation should be performed for each transmitter gather. Tests with synthetic and field data indicate that remarkably good tomographic reconstructions can be obtained using a single estimated source pulse when moderate to strong variability exists in the true source signal with antenna location. Only in the case of very strong variability in the true source pulse are tomographic reconstructions clearly improved by estimating a different source wavelet for each transmitter location.

Combined or sequential DMEK in cases of cataract and Fuchs endothelial corneal dystrophy—A systematic review and meta‐analysis
Vito Romano, Maria Laura Passaro, Björn Bachmann, Lamis Baydoun +4 more
2023· Acta Ophthalmologica20doi:10.1111/aos.15691

Abstract To compare the outcomes of Descemet membrane endothelial keratoplasty (DMEK) performed after phacoemulsification and intraocular lens (IOL) implantation (sequential DMEK) and DMEK combined with phacoemulsification and IOL implantation (combined DMEK) in patients with Fuchs endothelial corneal dystrophy (FECD) and cataract. Systematic literature review and meta‐analysis performed according to the PRISMA guidelines and registered in PROSPERO. Literature searches were conducted in Medline and Scopus. Comparative studies reporting sequential DMEK and combined DMEK in FECD patients were included. The main outcome measure of the study was the corrected distance visual acuity (CDVA) improvement. Secondary outcomes were postoperative endothelial cell density (ECD), rebubbling rate and primary graft failure rate. Bias risk was assessed and a quality appraisal of the body of evidence was completed using the Cochrane Robin‐I tool. A total of 667 eyes (5 studies) were included in this review, 292 eyes (43.77%) underwent a combined DMEK, while 375 (56.22%) eyes underwent a sequential DMEK surgery. We found no evidence of a difference between the two groups (mean difference, 95% CI) regarding: (1) CDVA improvement (−0.06; −0.14, 0.03 LogMAR; 3 studies, I 2 : 0%; p = 0.86); (2) postoperative ECD (−62; −190, 67 cells/mm 2 ; 4 studies, I 2 : 67%; p = 0.35); (3) rebubbling (risks ratio: 1.04; 0.59, 1.85; 4 studies, I 2 : 48%; p = 0.89); and primary graft failure rate (risks ratio: 0.91; 0.32, 2.57; 3 studies, I 2 : 0%; p = 0.86). Of all the 5 non‐randomized studies, all (100%) were graded as low quality. The overall quality of the analysed studies was low. Randomized controlled trials are needed to confirm no difference or superiority of one approach in terms of CDVA, endothelial cell count and postoperative complication rate between the two arms.

Comment and discussion on digital processing of PD pulses
Péter Osváth, G. Zingales, R. Bartnikas, M.M.A. Salama +4 more
1995· IEEE Transactions on Dielectrics and Electrical Insulation15doi:10.1109/94.407033

Some of the more salient aspects of the digital processing technology of PD signals are examined. Most of the efforts in this field are concentrated on the application of digital analyzers for pulse height analysis, pattern recognition and identification of the physical phenomena. It is demonstrated that errors in the signal processing unit can lead to dominant mistakes in the interpretation of the test results.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Multiple Sclerosis: A Disease of Affluence?
Bernhard Buchter, Margrit Dunkel, Jianghong Li
2012· Neuroepidemiology13doi:10.1159/000338676

&lt;b&gt;&lt;i&gt;Background:&lt;/i&gt;&lt;/b&gt; Multiple sclerosis is rare in tropical areas, but quite common in developed countries. Hence, latitude has been accepted as a causal factor for prevalence of multiple sclerosis. However, developed countries have also strong economic power, which may be measured by real gross domestic product per capita. &lt;b&gt;&lt;i&gt;Methods:&lt;/i&gt;&lt;/b&gt; Bivariate and multivariate regression models were used to assess the association of the prevalence of multiple sclerosis of 62 countries with real gross domestic product per capita and latitude. &lt;b&gt;&lt;i&gt;Results:&lt;/i&gt;&lt;/b&gt; Real gross domestic product per capita and latitude are positively associated with the prevalence of multiple sclerosis. Real gross domestic product per capita is a much stronger predictor of prevalence of multiple sclerosis than latitude. &lt;b&gt;&lt;i&gt;Conclusion:&lt;/i&gt;&lt;/b&gt; The strong correlation between the real gross domestic product per capita and the prevalence rates of multiple sclerosis is pointing to a new direction in research on the causes of multiple sclerosis. It is plausible that certain lifestyles and consumption behaviors that require high purchasing power might be associated with an increased risk of multiple sclerosis.

40 GHz pulse generating source with less than 350 fs timing jitter
G.J. Spühler, M. J. P. Dymott, Igor V. Klimov, G. Luntz +4 more
2002· Electronics Letters13doi:10.1049/el:20020722

A simple 40 GHz pulse source combining a fundamentally modelocked 10 GHz laser with a planar waveguide integrated time-division multiplexer is demonstrated. Pulse trains with &gt;5 dBm average power and &lt;350 fs rms timing jitter were achieved.

Tunable picosecond pulse-generating laser with a repetition rate exceeding 10 GHz
G.J. Spühler, Igor V. Klimov, Catherine Y. Teisset, K. J. Weingarten +3 more
200311doi:10.1109/ofc.2002.1036382

In conclusion, we have demonstrated a simple pulse-generating laser operating at frequencies exceeding 10 GHz with picosecond pulses and average power exceeding 10 mW, tunable over the entire C-band. Compact micromechanical packaging of this device will enable applications in RZ and dispersion-managed DWDM systems, highspeed test and measurement, and all-optical functionality such as 3R and wavelength conversion. The high output power and a very high extinction ratio enable simple time division multiplexing to 40 GHz or higher while still yielding a high quality pulse train.

PHOTOOXYGENOLYSIS OF VITAMIN B<sub>12</sub> and RELATED CORRINS: COBALT(III)CORRINS AS SUBSTRATES and QUENCHERS FOR SINGLET OXYGEN (1Δ<sub>g</sub>)*
Bernhard Kraeutler, René Stepánek
1991· Photochemistry and Photobiology8doi:10.1111/j.1751-1097.1991.tb02060.x

Abstract Under photooxygenolytic conditions, vitamin B 12 can be degraded to two isomeric dioxosec‐ocorrins by a regioselective oxygenolytic cleavage of the corrin macrocycle (preliminary report in Krautler and Stepanek (1985), Angew. Chem. 97 ,71–73; Angew. Chem. Intl. Ed. Engl. 24 ,62–64): irradiation of an oxygen saturated solution of vitamin B 12 ( 1 ), of KCN and of methylene blue (molar ratio (1:1:0.005) in CD 3 OD at ca 200 K with visible light led to a selective oxygenolysis of the vitamin. The two products, potassium Co α Co β ‐dicyano‐5,6‐dioxo‐5,6‐seco‐5′6′‐dimethylbenzimidazolyl‐cobam‐idate ( 3 , 10% yield) and potassium Co α Co β ‐dicyano‐14,15‐dioxo‐14,15‐seco‐5′6′‐dimetliylbenzirnida‐zolyl‐cobamidate (4, 25% yield), and 1 (31% yield) were chromatographically separated and isolated. The structures were established spectroanalytically, and by the help of an acid catalyzed methanolysis of 3 and 4 to the related Co α Co β ‐dicyano‐heptamethyl‐ dioxosecocobyrinates (6 and 7). When irradiated with visible light in any oxygen saturated methanolic solution containing methylene blue, vitamin B 12 itself exhibited considerable inertness. Only upon addition of a stoichiometric amount of KCN to such a solution (to afford the adduct 2) did the photolysis lead to oxygenation of the cobaltcorrin within a useful time. The regioselectivity of the oxygenolysis of 2 and the ratio of products formed are comparable to the outcome of the photooxygenolysis of the structurally related heptamethylcobyrinate 5 (Kräutler (1982) Helv. Chim. Acta 65 ,1941–1948). The reaction at the methyl‐substituted meso‐positions of the corrin macrocycle is indicated to involve singlet oxygen ( 1 Δ g ). In support of this interpretation, the preparative photolysis of 2 at 200 K also turned out to be about 7 times slower when CH 3 OH was used instead of CD 3 OD.