Large granulation cells on the surface of the giant star π1 Gruis.

Convection plays a major part in many astrophysical processes, including energy transport, pulsation, dynamos and winds on evolved stars, in dust clouds and on brown dwarfs. Most of our knowledge about stellar convection has come from studying the Sun: about two million convective cells with typical sizes of around 2,000 kilometres across are present on the surface of the Sun-a phenomenon known as granulation. But on the surfaces of giant and supergiant stars there should be only a few large (several tens of thousands of times larger than those on the Sun) convective cells, owing to low surface gravity. Deriving the characteristic properties of convection (such as granule size and contrast) for the most evolved giant and supergiant stars is challenging because their photospheres are obscured by dust, which partially masks the convective patterns. These properties can be inferred from geometric model fitting, but this indirect method does not provide information about the physical origin of the convective cells. Here we report interferometric images of the surface of the evolved giant star π1 Gruis, of spectral type S5,7. Our images show a nearly circular, dust-free atmosphere, which is very compact and only weakly affected by molecular opacity. We find that the stellar surface has a complex convective pattern with an average intensity contrast of 12 per cent, which increases towards shorter wavelengths. We derive a characteristic horizontal granule size of about 1.2 × 1011 metres, which corresponds to 27 per cent of the diameter of the star. Our measurements fall along the scaling relations between granule size, effective temperature and surface gravity that are predicted by simulations of stellar surface convection.

A deep-learning method for the denoising of ultra-low dose chest CT in coronary artery calcium score evaluation.

AIM: To evaluate a novel deep-learning denoising method for ultra-low dose CT (ULDCT) in the assessment of coronary artery calcium score (CACS). MATERIALS AND METHODS: Sixty adult patients who underwent two unenhanced chest CT examinations, a normal dose CT (NDCT) and an ULDCT, were enrolled prospectively between September 2017 to December 201. A special training set was created to learn the characteristics of the real noise affecting the ULDCT implementing a fully convolutional neural network with batch normalisation. Subsequently, the 60 ULDCTs of the evaluation set were denoised. Two blinded radiologists assessed the NDCT, ULDCT, and denoised-ULDCT (DULDCT), assigning a CACS and categorised each scan as having a score above or below 100 and presence of calcifications (score 0 versus >0). Statistical analysis was used to evaluate the agreement between the readers and differences in CACSs between each imaging method. RESULTS: After excluding one patient, the cohort included 59 patients (median age 67 years, 58% men). The ULDCT median effective radiation dose (ERD) was 0.172 mSv, which was 2.8% of the NDCT median ERD. Denoising improved the signal-to-noise ratio by 27.7% (p<0.001). Interobserver agreement was almost perfect between readers (intraclass correlation coefficient >0.993). CACSs were lower for ULDCT and DULDCT as compared to the NDCT (p ≤ 0.001). In differentiating between the presence and absence of coronary artery calcifications, DULDCT showed greater accuracy (98-100%) and positive likelihood ratio (14.29->99) compared to ULDCT (92% and 2.78, respectively). CONCLUSION: DULCT significantly reduced the image noise and better identified patients with no coronary artery calcifications than native ULDCT.

The Developmental Chronnecto-Genomics (Dev-CoG) study: A multimodal study on the developing brain.

Brain development has largely been studied through unimodal analysis of neuroimaging data, providing independent results for structural and functional data. However, structure clearly impacts function and vice versa, pointing to the need for performing multimodal data collection and analysis to improve our understanding of brain development, and to further inform models of typical and atypical brain development across the lifespan. Ultimately, such models should also incorporate genetic and epigenetic mechanisms underlying brain structure and function, although currently this area is poorly specified. To this end, we are reporting here a multi-site, multi-modal dataset that captures cognitive function, brain structure and function, and genetic and epigenetic measures to better quantify the factors that influence brain development in children originally aged 9-14 years. Data collection for the Developmental Chronnecto-Genomics (Dev-CoG) study (http://devcog.mrn.org/) includes cognitive, emotional, and social performance scales, structural and functional MRI, diffusion MRI, magnetoencephalography (MEG), and saliva collection for DNA analysis of single nucleotide polymorphisms (SNPs) and DNA methylation patterns. Across two sites (The Mind Research Network and the University of Nebraska Medical Center), data from over 200 participants were collected and these children were re-tested annually for at least 3 years. The data collection protocol, sample demographics, and data quality measures for the dataset are presented here. The sample will be made freely available through the collaborative informatics and neuroimaging suite (COINS) database at the conclusion of the study.

A perspective on the role of uncertainty in sustainability science and engineering.

The Trans-Atlantic Research and Development Interchange on Sustainability Workshop (TARDIS) is a meeting on scientific topics related to sustainability. The 2019 workshop theme was "On the Role of Uncertainty in Managing the Earth for Global Sustainability." This paper presents the perspectives on this topic derived from talks and discussions at the 2019 TARDIS workshop. There are four kinds of uncertainties encountered in sustainability ranging from clear enough futures to true surprises. The current state-of-the-art in assessing and mitigating these uncertainties is discussed.

Caffeine prevents prostaglandin E1-induced disturbances in respiratory control in neonatal rats: implications for infants with critical congenital heart disease.

Continuous infusion of prostaglandin E1 (PGE1) is used to maintain ductus arteriosus patency in infants with critical congenital heart disease, but it can also cause central apnea suggesting an effect on respiratory neural control. In this study, we investigated whether 1) PGE1 inhibits the various phases of the acute hypoxic ventilatory response (HVR; an index of respiratory control dysfunction) and increases apnea incidence in neonatal rats; and 2) whether these changes would be reversible with caffeine pretreatment. Whole body plethysmography was used to assess the HVR and apnea incidence in neonatal rats 2 h following a single bolus intraperitoneal injection of PGE1 with and without prior caffeine treatment. Untreated rats exhibited a biphasic HVR characterized by an initial increase in minute ventilation followed by a ventilatory decline of the late phase (~5th minute) of the HVR. PGE1 had a dose-dependent effect on the HVR. Contrary to our hypothesis, the lowest dose (1 µg/kg) of PGE1 prevented the ventilatory decline of the late phase of the HVR. However, PGE1 tended to increase postsigh apnea incidence and the coefficient of variability (CV) of breathing frequency, suggesting increased respiratory instability. PGE1 also decreased brainstem microglia mRNA and increased neuronal nitric oxide synthase (nNOS) and platelet-derived growth factor-ß (PDGF-ß) gene expression. Caffeine pretreatment prevented these effects of PGE1, and the adenosine A2A receptor inhibitor MSX-3 had similar preventative effects. Prostaglandin appears to have deleterious effects on brainstem respiratory control regions, possibly involving a microglial-dependent mechanism. The compensatory effects of caffeine or MSX-3 treatment raises the question of whether prostaglandin may also operate on an adenosine-dependent pathway.

Aboriginal community controlled health organisations address health equity through action on the social determinants of health of Aboriginal and Torres Strait Islander peoples in Australia.

BACKGROUND: Indigenous populations globally are continually striving for better health and wellbeing due to experiencing significant health and social inequities. The social determinants of health are important contributors to health outcomes. Comprehensive primary health care that is governed and delivered by Indigenous people extends beyond the biomedical model of care to address the social determinants of health. Aboriginal Community Controlled Health Organisations (ACCHOs) are known to provide culturally informed, holistic health services that directly and indirectly address the social determinants of health. The range and extent of their activities in addressing the social determinants of health, however, is not well documented. METHODS: The most recent ACCHO annual reports were retrieved online or by direct correspondence. For coding consistency, a dictionary informed by the World Health Organization's Conceptual Framework for Action on the Social Determinants of Health was developed. A document and textual analysis of reports coded ACCHO activities and the determinants of health they addressed, including intermediary determinants, socio-economic position and/or socio-political context. Summary statistics were reported. Representative quotes illustrating the unique nature of ACCHO service provision in addressing the social determinants of health were used to contextualise the quantitative findings. RESULTS: Sixty-seven annual reports were collected between 2017 and 2018. Programs were delivered to population groups across the life span. Fifty three percent of reports identified programs that included work at the socio-political level and all annual reports described working to improve socioeconomic position and intermediary determinants of health through their activities. Culture had a strong presence in program delivery and building social cohesion and social capital emerged as themes. CONCLUSIONS: This study provides evidence of the considerable efforts of the ACCHO sector, as a primary health care provider, in addressing the social determinants of health and health inequity experienced by Indigenous communities. For the Aboriginal and Torres Strait Islander population, ACCHOs not only have an essential role in addressing immediate healthcare needs but also invest in driving change in the more entrenched structural determinants of health. These are important actions that are likely to have an accumulative positive effect in closing the gap towards health equity.

Tightly locked optical frequency comb from a semiconductor disk laser.

Ultrafast semiconductor disk lasers (SDLs) passively modelocked using semiconductor saturable absorbers mirrors (SESAMs) generate optical frequency combs (OFCs) with gigahertz line spacings - a regime where solid-state and fiber lasers struggle with geometrical and Q-switching limitations. We stabilized both the frequency comb spacing and the offset without any additional external optical amplification or pulse compression. The overall noise performance is competitive with other gigahertz OFCs. A SESAM-modelocked vertical external-cavity surface-emitting laser (VECSEL) at a center wavelength around 1 µm generates 122-fs pulses with 160 mW average output power and we only needed 17-pJ pulse energy coupled into a silicon nitride (Si3N4) waveguide for supercontinuum generation (SCG) and OFC offset stabilization.

Intranasal administration of allergen increases specific IgE whereas intranasal omalizumab does not increase serum IgE levels-A pilot study.

BACKGROUND: Administration of the therapeutic anti-IgE antibody omalizumab to patients induces strong increases in IgE antibody levels. OBJECTIVE: To investigate the effect of intranasal administration of major birch pollen allergen Bet v 1, omalizumab or placebo on the levels of total and allergen-specific IgE in patients with birch pollen allergy. METHODS: Based on the fact that intranasal allergen application induces rises of systemic allergen-specific IgE, we performed a double-blind placebo-controlled pilot trial in which birch pollen allergic subjects were challenged intranasally with omalizumab, placebo or birch pollen allergen Bet v 1. Total and allergen-specific IgE, IgG and basophil sensitivity were measured before and 8 weeks after challenge. For control purposes, total, allergen-specific IgE levels and omalizumab-IgE complexes as well as specific IgG levels were studied in subjects treated subcutaneously with either omalizumab or placebo. Effects of omalizumab on IgE production by IL-4/anti-CD40-treated PBMCs from allergic patients were studied in vitro. RESULTS: Intranasal challenge with Bet v 1 induced increases in Bet v 1-specific IgE levels by a median of 59.2%, and this change differed significantly from the other treatment groups (P = .016). No relevant change in allergen-specific and total IgE levels was observed in subjects challenged with omalizumab. Addition of omalizumab did not enhance IL-4/anti-CD40-induced IgE production in vitro. Significant rises in total IgE (mean IgE before: 131.83 kU/L to mean IgE after: 505.23 kU/L) and the presence of IgE-omalizumab complexes were observed after subcutaneous administration of omalizumab. CONCLUSION: Intranasal administration of allergen induced rises of allergen-specific IgE levels, whereas intranasal administration of omalizumab did not enhance systemic total or allergen-specific IgE levels.

Morphological changes of the internal carotid artery: prevalence and characteristics. A clinical and ultrasonographic study in a series of 19 804 patients over 25 years old.

BACKGROUND AND PURPOSE: Morphological changes of the internal carotid arteries (McICA) are frequently found during cervical ultrasound studies. However, the etiology of McICA remains controversial. During this study, the prevalence and demographic characteristics of McICA, such as kinking, coiling or looping identified by Doppler ultrasound, were analysed and its relationship with vascular risk factors and stroke was assessed. METHODS: A retrospective study was performed by analysing 19 804 patients who were subjected to cervical ultrasonographic study between January 2000 and June 2012. The data were statistically analysed with SPSS® 20 and a multivariate logistic regression was performed. Statistical significance was accepted for P < 0.05 and 95% confidence intervals (CIs) were used. RESULTS: Morphological changes of the internal carotid arteries were present in 2678 patients (13.5%) and were unilateral in 61.6% of these cases. Carotid kinking was found in 80% of the patients, coiling in 16% and looping in 1%. In multivariate analysis, the presence of McICA was related to older groups (1.04; 95% CI, 1.04-1.05; P < 0.01), female gender (1.78; 95% CI, 1.64-1.94; P < 0.01), patients with hyperlipidemia (1.28; 95% CI, 1.17-1.40; P < 0.01), carotid thickness (1.22; 95% CI, 1.13-1.33; P < 0.01) and cardiac or cardioembolic disease (1.11; 95% CI, 1.01-1.21; P = 0.02). The results of this study indicate that kinking in the carotid artery was associated with ipsilateral cerebral ischemic events (1.43; 95% CI, 1.040-1.958; P < 0.05). CONCLUSION: Morphological changes of the internal carotid arteries were associated with aging, female gender and patients with hyperlipidemia, hypertension, diabetes and heart disease. Kinking was associated with ipsilateral cerebral ischemia.

BMP15 "knockout-like" effect in familial premature ovarian insufficiency with persistent ovarian reserve.

Premature ovarian insufficiency (POI) affects 1% to 2% of women under 40 years. Bone morphogenetic protein 15 (BMP15) variants have been described in POI. We studied a family with 2 sisters compound heterozygous for deletions in the BMP15 gene on chromosome Xp11.22 yielding a human "knockout-like" effect: a c.151_152delGA deletion yielded a p.Glu51IlefsTer27 mutation transmitted by the hemizygous father and a c.189_198delAGGGCATTCAinsTG deletion/insertion yielded a p.Glu64AlafsTer12 mutation transmitted by the heterozygous mother. Both deletions resulted in frameshifts with premature stop codons at positions 78 and 76 in the proregion, precluding mature BMP15 production. One sister had primary amenorrhea and the other primo-secondary amenorrhea. No bone abnormality was observed. Despite streak ovaries devoid of follicles on ultrasonography, anti-Mullerian hormone (AMH) levels were low but detectable suggesting the presence of growing follicles. Five years later, AMH was undetectable in both sisters, 1 had received an egg donation. BMP15 did not seem critical for follicles to enter the growth phase. Genetic counselling should be performed and fertility preservation discussed before progressive loss of follicular reserve. The fertile heterozygous mother did not support previous reports of BMP15 haploinsufficiency and gene dosage in humans, as in bovine species. The hemizygous brother had asthenozoospermia, consistent with previous observations in bulls with a variant BMP15.

[German national consensus on wound documentation of leg ulcer : Part 1: Routine care - standard dataset and minimum dataset]. / Nationaler Konsensus zu Wunddokumentation beim Ulcus cruris : Teil 1: Routineversorgung ­ "Standard-Dataset" und "Minimum-Dataset".

BACKGROUND: Standards for basic documentation and the course of treatment increase quality assurance and efficiency in health care. To date, no standards for the treatment of patients with leg ulcers are available in Germany. OBJECTIVES: The aim of the study was to develop standards under routine conditions in the documentation of patients with leg ulcers. This article shows the recommended variables of a "standard dataset" and a "minimum dataset". MATERIALS AND METHODS: Consensus building among experts from 38 scientific societies, professional associations, insurance and supply networks (n = 68 experts) took place. After conducting a systematic international literature research, available standards were reviewed and supplemented with our own considerations of the expert group. From 2012-2015 standards for documentation were defined in multistage online visits and personal meetings. RESULTS: A consensus was achieved for 18 variables for the minimum dataset and 48 variables for the standard dataset in a total of seven meetings and nine online Delphi visits. The datasets involve patient baseline data, data on the general health status, wound characteristics, diagnostic and therapeutic interventions, patient reported outcomes, nutrition, and education status. DISCUSSION: Based on a multistage continuous decision-making process, a standard in the measurement of events in routine care in patients with a leg ulcer was developed.

[German national consensus on wound documentation of leg ulcer : Part 2: Routine care - classification of variable characteristics]. / Nationaler Konsensus zur Wunddokumentation beim Ulcus cruris : Teil 2: Routineversorgung ­ Klassifikation der Variablenausprägungen.

BACKGROUND: Standards in the assessment and documentation of disease processes are the basis of guideline-based care. For the treatment of chronic wounds, especially leg ulcers, no approved parameters are available. OBJECTIVES: Against this background, our aim was to develop standards for the documentation of leg ulcer in routine care. This article presents the recommendations for the classification and characteristics of the variables. MATERIALS AND METHODS: The development of the documentation standard was based on a systematic literature research and was performed in a Delphi-based consensus process. The national consensus process included meetings as well as web-based questionnaires. The Consensus Group is coordinated by the German Center for Health Services Research in Dermatology (CVderm). RESULTS: The documentation standards and their variables for leg ulcer routine care were developed in seven meetings of the consensus group. The consensus group consists of 38 delegates of wound care societies, health insurances, wound networks and associations. DISCUSSION: For each variable, recommended in routine care, a distinct response scheme (defined set of variable characteristics) was defined. As a next step, a structured implementation process is required, which was part of the resolutions of the consensus group.

Single and Double Beta-Decay Q Values among the Triplet

The atomic mass relations among the mass triplet ^{96}Zr, ^{96}Nb, and ^{96}Mo have been determined by means of high-precision mass measurements using the JYFLTRAP mass spectrometer at the IGISOL facility of the University of Jyväskylä. We report Q values for the ^{96}Zr single and double ß decays to ^{96}Nb and ^{96}Mo, as well as the Q value for the ^{96}Nb single ß decay to ^{96}Mo, which are Q_{ß}(^{96}Zr)=163.96(13), Q_{ßß}(^{96}Zr)=3356.097(86), and Q_{ß}(^{96}Nb)=3192.05(16) keV. Of special importance is the ^{96}Zr single ß-decay Q value, which has never been determined directly. The single ß decay, whose main branch is fourfold unique forbidden, is an alternative decay path to the ^{96}Zr ßß decay, and its observation can provide one of the most direct tests of the neutrinoless ßß-decay nuclear-matrix-element calculations, as these can be simultaneously performed for both decay paths with no further assumptions. The theoretical single ß-decay rate has been re-evaluated using a shell-model approach, which indicates a ^{96}Zr single ß-decay lifetime within reach of an experimental verification. The uniqueness of the decay also makes such an experiment interesting for an investigation into the origin of the quenching of the axial-vector coupling constant g_{A}.

Report from the kick-off meeting of the Cochrane Skin Group Core Outcome Set Initiative (CSG-COUSIN).

A major obstacle of evidence-based clinical decision making is the use of nonstandardized, partly untested outcome measurement instruments. Core Outcome Sets (COSs) are currently developed in different medical fields to standardize and improve the selection of outcomes and outcome measurement instruments in clinical trials, in order to pool results of trials or to allow indirect comparison between interventions. A COS is an agreed minimum set of outcomes that should be measured and reported in all clinical trials of a specific disease or trial population. The international, multidisciplinary Cochrane Skin Group Core Outcome Set Initiative (CSG-COUSIN) aims to develop and implement COSs in dermatology, thus making trial evidence comparable and, herewith, more useful for clinical decision making. The inaugural meeting of CSG-COUSIN was held on 17-18 March 2015 in Dresden, Germany, as the exclusive theme of the Annual Cochrane Skin Group Meeting. In total, 29 individuals representing a broad mix of different stakeholder groups, professions, skills and perspectives attended. This report provides a description of existing COS initiatives in dermatology, highlights current methodological challenges in COS development, and presents the concept, aims and structure of CSG-COUSIN.

Lateralization of resting state networks and relationship to age and gender.

Brain lateralization is a widely studied topic, however there has been little work focused on lateralization of intrinsic networks (regions showing similar patterns of covariation among voxels) in the resting brain. In this study, we evaluate resting state network lateralization in an age and gender-balanced functional magnetic resonance imaging (fMRI) dataset comprising over 600 healthy subjects ranging in age from 12 to 71. After establishing sample-wide network lateralization properties, we continue with an investigation of age and gender effects on network lateralization. All data was gathered on the same scanner and preprocessed using an automated pipeline (Scott et al., 2011). Networks were extracted via group independent component analysis (gICA) (Calhoun et al., 2001). Twenty-eight resting state networks discussed in previous (Allen et al., 2011) work were re-analyzed with a focus on lateralization. We calculated homotopic voxelwise measures of laterality in addition to a global lateralization measure, called the laterality cofactor, for each network. As expected, many of the intrinsic brain networks were lateralized. For example, the visual network was strongly right lateralized, auditory network and default mode networks were mostly left lateralized. Attentional and frontal networks included nodes that were left lateralized and other nodes that were right lateralized. Age was strongly related to lateralization in multiple regions including sensorimotor network regions precentral gyrus, postcentral gyrus and supramarginal gyrus; and visual network regions lingual gyrus; attentional network regions inferior parietal lobule, superior parietal lobule and middle temporal gyrus; and frontal network regions including the inferior frontal gyrus. Gender showed significant effects mainly in two regions, including visual and frontal networks. For example, the inferior frontal gyrus was more right lateralized in males. Significant effects of age were found in sensorimotor and visual networks on the global measure. In summary, we report a large-sample of lateralization study that finds intrinsic functional brain networks to be highly lateralized, with regions that are strongly related to gender and age locally, and with age a strong factor in lateralization, and gender exhibiting a trend-level effect on global measures of laterality.

Frequency comb offset detection using supercontinuum generation in silicon nitride waveguides.

We present the first direct carrier-envelope-offset (CEO) frequency detection of a modelocked laser based on supercontinuum generation (SCG) in a CMOS-compatible silicon nitride (Si(3)N(4)) waveguide. With a coherent supercontinuum spanning more than 1.5 octaves from visible to beyond telecommunication wavelengths, we achieve self-referencing of SESAM modelocked diode-pumped Yb:CALGO lasers using standard f-to-2f interferometry. We directly obtain without amplification strong CEO beat signals for both a 100-MHz and 1-GHz pulse repetition rate laser. High signal-to-noise ratios (SNR) of > 25 dB and even > 30 dB have been generated with only 30 pJ and 36 pJ of coupled pulse energy from the megahertz and gigahertz laser respectively. We compare these results to self-referencing using a commercial photonic crystal fiber and find that the required peak power for CEO beat detection with a comparable SNR is lowered by more than an order of magnitude when using a Si(3)N(4) waveguide.

Temperature-Dependent Three-Dimensional Anisotropy of the Magnetoresistance in WTe_{2}.

Extremely large magnetoresistance (XMR) was recently discovered in WTe_{2}, triggering extensive research on this material regarding the XMR origin. Since WTe_{2} is a layered compound with metal layers sandwiched between adjacent insulating chalcogenide layers, this material has been considered to be electronically two-dimensional (2D). Here we report two new findings on WTe_{2}: (1) WTe_{2} is electronically 3D with a mass anisotropy as low as 2, as revealed by the 3D scaling behavior of the resistance R(H,θ)=R(ϵ_{θ}H) with ϵ_{θ}=(cos^{2}θ+γ^{-2}sin^{2}θ)^{1/2}, θ being the magnetic field angle with respect to the c axis of the crystal and γ being the mass anisotropy and (2) the mass anisotropy γ varies with temperature and follows the magnetoresistance behavior of the Fermi liquid state. Our results not only provide a general scaling approach for the anisotropic magnetoresistance but also are crucial for correctly understanding the electronic properties of WTe_{2}, including the origin of the remarkable "turn-on" behavior in the resistance versus temperature curve, which has been widely observed in many materials and assumed to be a metal-insulator transition.

Meningococcal disease in childhood: epidemiology, clinical features and prevention.

Invasive meningococcal disease (IMD) represents a public health problem and a leading cause of morbidity and mortality worldwide. IMD can occur as an endemic disease with sporadic cases or epidemics with outbreaks. Neisseria meningitis strains are divided into 13 serogroups, but only five (A, B, C, W-135, and Y) are responsible for most IMD across the world. All age groups are at risk for IMD, but infants and adolescents are particularly vulnerable. The most common clinical manifestations of IMD are meningitis and septicemia, although in some cases both clinical pictures are present. The clinical pattern can differ according to age; in young children, the clinical manifestations may be more insidious and the diagnosis may be more difficult compared to older children or adolescents. Death occurs in 6-10% of cases and sequelae in 4.3-11.2% of cases. Early recognition of children with meningococcal infection is important in order to initiate systemic antibiotic therapy, although vaccination remains the best strategy to control meningococcal disease. Recently, different meningococcal vaccines have been introduced worldwide, resulting in a reduction in the overall burden of the disease. The goal of the next few years should be to increase vaccination coverage against meningococcal diseases, continue to monitor IMD and develop a unique vaccine able to cover all of the main meningococcal strains.

SESAM modelocked Yb:CaGdAlO4 laser in the soliton modelocking regime with positive intracavity dispersion.

We demonstrate femtosecond SESAM modelocking in the near-infrared by using cascaded quadratic nonlinearities (phase-mismatched second-harmonic generation, SHG), enabling soliton modelocking in the normal dispersion regime without any dispersion compensating elements. To obtain large and negative self-phase modulation (SPM) we use an intracavity LBO crystal, whose temperature and angles are optimized with respect to SPM, nonlinear losses, and self-starting characteristics. To support femtosecond pulses, we use the very promising Yb:CaGdAlO(4) (CALGO) gain material, operated in a bulk configuration. The LBO crystal provides sufficient negative SPM to compensate for its own GDD as well as the positive GDD and SPM from the gain crystal. The modelocked laser produces pulses of 114 fs at 1050 nm, with a repetition rate of 113 MHz (average output power 1.1 W). We perform a detailed theoretical study of this soliton modelocking regime with positive GDD, which clearly indicates the important design constraints in an intuitive and systematic way. In particular, due to its importance in avoiding multi-pulsed modelocking, we examine the nonlinear loss associated with the cascading process carefully and show how it can be suppressed in practice. With this modelocking regime, it should be possible to overcome the limits faced by current state of the art modelocked lasers in terms of dispersion compensation and nonlinearity management at high powers, suppression of Q-switching in compact GHz lasers, and enabling femtosecond soliton modelocking at very high repetition rates due to the high nonlinearities accessible via cascading combined with eliminating the need for intracavity dispersion compensation.

Quantitative adsorbate structure determination for quasicrystals using x-ray standing waves.

The quantitative structure determination of adsorbed species on quasicrystal surfaces has so far appeared to present insurmountable problems. The normal incidence standing x-ray wave field technique offers a simple solution, without extensive data sets or large computations. Its application to quasicrystals raises several conceptual difficulties that are related to the phase problem in x-ray diffraction. We demonstrate their solution for the case of Si atoms adsorbed on the decagonal Co-rich modification of the Al-Co-Ni quasicrystal to determine the local structure, comprising 6-atom clusters in particular hollow sites.