Random lasing from optical fibers with phase separated glass cores.

A novel random laser, integrating a passive optical fiber with a phase separated aluminosilicate core-silica cladding as the feedback medium, is proposed and presented. The core exhibits greatly enhanced Rayleigh scattering, therefore requiring a significantly reduced length of scattering fiber (4 m) for lasing. With a Yb-doped fiber as the gain medium, the fiber laser operates at 1050 nm with low threshold power and possesses an output that can be amplified through conventional means. Furthermore, the laser was found to have a high degree of spatial coherence, spectral broadening with increasing input power, and temporal spectral variation. The facile setup and results herein pave the way for further study and applications based on low threshold random fiber lasers.

Targeted endodontic microsurgery and endodontic microsurgery: a surgical simulation comparison.

AIM: To compare surgical time, bevel angle and site volumetric profiles of osteotomy and resection accomplished by targeted endodontic microsurgery (TEMS) and traditional endodontic microsurgery (EMS) in a surgical simulation model. METHODOLOGY: An 80x80-mm cone beam computed tomography (CBCT) file was imported into Mimics software where artificial periapical lesions were created encompassing twelve root apices. Maxillary and mandibular models were 3D-printed. TEMS surgical guides were designed and 3D-printed for each surgical site. Three board-certified endodontists used the original CBCT to plan and perform EMS on models of six maxillary and six mandibular teeth. Next, the same endodontists performed TEMS on duplicate 3D-printed models for the same teeth. All surgeries were timed. Postoperative CBCT images of experimental models were made and imported into Amira software for measurement of bevel angle and site volumetric profiles. Paired t-tests compared the mean differences between EMS and TEMS groups. A Bonferroni correction determined data to be significant at P < 0.004. RESULTS: TEMS significantly reduced surgical time (P < 0.00001), had bevel angles more closely approaching zero degrees (P < 0.01) and had significantly less volume of over-resection (P < 0.001) and length of root resection (P < 0.01). CONCLUSIONS: In this surgical simulation scenario, TEMS provided more efficient completion of osteotomy and resection, with a more appropriate root-end resection volume and bevel angle.

Cost-effectiveness of first-trimester screening with early preventative use of aspirin in women at high risk of early-onset pre-eclampsia.

OBJECTIVE: Pre-eclampsia (PE) remains a leading cause of maternal and fetal morbidity and mortality. A first-trimester screening algorithm predicting the risk of early-onset PE has been developed and validated. Early prediction coupled with initiation of aspirin at 11-13 weeks in women identified as high risk is effective at reducing the prevalence of early-onset PE. The aim of this study was to evaluate the cost-effectiveness of this first-trimester screening program coupled with early use of low-dose aspirin in women at high risk of developing early-onset PE, in comparison to current practice in Canada. METHODS: A decision analysis was performed based on a theoretical population of 387 516 live births in Canada in 1 year. The clinical and financial impact of early preventative screening using the Fetal Medicine Foundation algorithm for prediction of early-onset PE coupled with early (< 16 weeks) use of low-dose aspirin in those at high risk was simulated and compared with current practice using decision-tree analysis. The probabilities at each decision point and associated costs of utilized resources were calculated based on published literature and public databases. RESULTS: Of the theoretical 387 516 births per year, the estimated prevalence of early PE based on first-trimester screening and aspirin use was 705 vs 1801 cases based on the current practice. This was associated with an estimated total cost of C$9.52 million with the first-trimester screening program compared with C$23.91 million with current practice for the diagnosis and management of women with early-onset PE. This equals an annual cost saving to the Canadian healthcare system of approximately C$14.39 million. CONCLUSIONS: The implementation of a first-trimester screening program for PE and early intervention with aspirin in women identified as high risk for early PE has the potential to prevent a significant number of early-onset PE cases with a substantial associated cost saving to the healthcare system in Canada. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Less than 1% quantum defect fiber lasers via ytterbium-doped multicomponent fluorosilicate optical fiber.

Two ytterbium-doped fiber lasers exhibiting quantum defects of less than 1% are demonstrated, in which pumping at wavelengths of 976.6 and 981.0 nm yielded lasing at wavelengths of 985.7 and 989.8 nm, respectively. The multicomponent fluorosilicate active optical fiber, fabricated using the molten core method, has spectral characteristics similar to those of fluoride glasses, namely short average emission wavelength and long upper state lifetime. A best-case slope efficiency of 62.1% was obtained, matching the theoretical model very well. With further fiber and laser optimization, slope efficiencies approaching the quantum limit should ultimately be possible. A reduction in the quantum defect may offer significant mitigation of issues associated with fiber heating. As such, this work can serve as a possible direction for future scaling of high-power fiber laser systems.

Highly nonlinear yttrium-aluminosilicate optical fiber with a high intrinsic stimulated Brillouin scattering threshold.

Highly nonlinear (high-NA small-mode-area) optical fibers also possessing an intrinsically high stimulated Brillouin scattering threshold are described. More specifically, silica clad, yttrium-aluminosilicate core fibers are shown to exhibit an intrinsically low Brillouin gain coefficient between 0.125 and 0.139×10-11 m/W and a Brillouin gain linewidth of up to 500 MHz. Losses on the order of 0.7 dB/m were measured, resulting from impurities in the precursor materials. Nonlinear refractive index values are determined to be similar to that of silica, but significant measurement uncertainty is attributed to the need to estimate dispersion curves since their direct measurement could not be made. The interest for highly nonlinear optical fibers with a low intrinsic Brillouin gain coefficient is expected to continue, especially with the growing developments of narrow-linewidth high-energy laser systems.

Polymer-clad silica fibers for tailoring modal area and dispersion.

We demonstrate higher-order-mode (Aeff up to ∼2000 µm2) propagation in a 100 µm outer diameter pure-silica fiber with a low-index polymer jacket commonly used for fiber laser pump guidance. This simple structure obviates the need for complex designs deemed necessary for realizing large-mode-area fibers. Modes ranging from HE1,12 to HE1,22 were found to propagate stably over 15 m in this fiber. The index step is approximately 4 times larger than that obtained with fluorine down doping; thus the fiber supports even higher-order modes, which may have implications for building rare-earth-doped fiber lasers or achieving enhanced dispersion tunability for high-energy fiber nonlinear phenomena.

Antineutrophil Cytoplasmic Antibody Induction due to Infection: A Patient with Infective Endocarditis and Chronic Hepatitis C.

While antineutrophil cytoplasmic antibody (ANCA) is often used as a diagnostic marker for certain vasculitides, ANCA induction in the setting of infection is much less common. In the case of infective endocarditis, patients may present with multisystem disturbances resembling an autoimmune process, cases that may be rendered even trickier to diagnose in the face of a positive ANCA. Though not always straightforward, distinguishing an infective from an inflammatory process is pivotal in order to guide appropriate therapy. We describe an encounter with a 43-year-old male with chronically untreated hepatitis C virus infection who featured ANCA positivity while hospitalized with acute bacterial endocarditis. His case serves as a reminder of two of the few infections known to uncommonly generate ANCA positivity. We also summarize previously reported cases of ANCA positivity in the context of endocarditis and hepatitis C infections.

Single- and few-moded lithium aluminosilicate optical fiber for athermal Brillouin strain sensing.

Results are presented toward realizing a true single-mode fiber whose Brillouin frequency shift is independent of temperature, while its dependence on strain is comparable to conventional high-silica-content single-mode fibers. Demonstrated here is a fiber with a negative thermal sensitivity dν/dT of -0.26 MHz/K and a strain sensitivity of +406 MHz/%. The suppression of the Brillouin thermal response is enabled by the large thermal expansion coefficient of the group I oxide-containing silica glass network.

Understanding Patient Perspectives on Specialized, Longitudinal, Postpartum, Cardiovascular Risk-Reduction Clinics.

Background: Females who experience hypertensive disorders of pregnancy (HDP) have an increased lifelong risk of cardiovascular disease. Thus, Canadian clinical practice guidelines recommend cardiovascular risk reduction follow-up after a patient has HDP. This study examined the experiences of patients with HDP who attended a specialized, longitudinal general internal medicine postpartum cardiovascular risk reduction clinic called PreVASC. PreVASC focuses on comprehensive cardiovascular risk reduction through cardiovascular risk factor screening and management tailored specifically for female patients after they have HDP. Methods: This multimethod study examined the experiences of female patients with HDP via the following: (i) a quantitative survey (summarized with descriptive statistics); (ii) semistructured qualitative patient phone interviews (results grouped thematically); and (iii) triangulation of qualitative themes with quantitative survey results. Results: Overall, 37% of eligible clinic patients (42 of 115) participated; 79% of participants (n = 33) reported being "very satisfied" with the PreVASC clinic's specialized longitudinal model of care, and 95% (n = 40) reported making at least one preventive health behaviour change after receiving individualized counselling on cardiovascular risk reduction. Qualitative results found improvements in patient-reported cardiovascular health knowledge, health behaviours, and health-related anxiety. A preference for in-person vs phone clinic visits was reported by participants. Conclusions: An in-person, general internal medicine specialist-led, longitudinal model of cardiovascular disease preventive care focused specifically on cardiovascular risk reduction after HDP had positive impacts on patient experience, health knowledge, and preventive health behaviours. This novel knowledge on patient preferences for a longitudinal, specialized model of care advances cardiovascular risk reduction tailored specifically for high-risk people after HDP.

Contexte: Les femmes qui sont atteintes de troubles hypertensifs de la grossesse (THG) présentent un risque accru de maladie cardiovasculaire durant leur vie. Par conséquent, les lignes directrices canadiennes de pratique clinique recommandent un suivi pour la réduction du risque cardiovasculaire après la survenue d'un THG. Cette étude visait à examiner l'expérience des patientes qui ont été atteintes de THG et qui ont fréquenté l'une des cliniques de médecine interne spécialisées dans la réduction du risque cardiovasculaire post-partum et offrant une prise en charge longitudinale (PreVASC). Les cliniques PreVASC se concentrent sur la réduction des risques cardiovasculaires globaux par la détection des facteurs de risque cardiovasculaire et une prise en charge spécialement adaptée pour les femmes qui ont subi un THG. Méthodologie: Cette étude visait à examiner l'expérience des femmes atteintes d'un THG en faisant appel à diverses méthodes : i) sondage quantitatif (résumé par des statistiques descriptives); ii) entrevues téléphoniques semi-structurées de nature qualitative avec des patientes (résultats regroupés par thèmes); et iii) triangulation des thèmes qualitatifs et des résultats du sondage quantitatif. Résultats: Globalement, 37 % des patientes admissibles (42 sur 115) ont participé à l'étude; 79 % des participantes (n = 33) ont déclaré être « très satisfaites ¼ du modèle de soins longitudinal spécialisé des cliniques PreVASC, et 95 % (n = 40) ont déclaré avoir adopté au moins un comportement préventif pour leur santé après avoir reçu des conseils personnalisés sur la réduction du risque cardiovasculaire. Les résultats qualitatifs obtenus auprès des patientes font état d'une amélioration des connaissances sur la santé cardiovasculaire, les comportements sains et l'anxiété liée à la santé. Les participantes ont dit préférer les visites cliniques en personne aux consultations par téléphone. Conclusions: L'adoption d'un modèle longitudinal de médecine interne comprenant des rencontres avec des spécialistes pour prévenir les maladies cardiovasculaires, en particulier réduire le risque cardiovasculaire après un THG a eu des effets positifs chez les patientes en ce qui concerne l'expérience, les connaissances en matière de santé et les comportements à adopter pour prévenir les problèmes de santé. Ces nouvelles connaissances sur les préférences des patientes à l'égard de soins longitudinaux spécialisés représentent un pas en avant dans la mise en place d'une approche personnalisée de réduction du risque cardiovasculaire pour les personnes présentant un risque élevé après un THG.

Brillouin spectroscopy of a novel baria-doped silica glass optical fiber.

Presented here for the first time to the best of our knowledge is a detailed Brillouin spectroscopic study of novel, highly-BaO-doped silica glass optical fibers. The fibers were fabricated utilizing a molten-core method and exhibited baria (BaO) concentrations up to 18.4 mole %. Physical characteristics such as mass density, acoustic velocity, visco-elastic damping, and refractive index are determined for the baria component of the bariosilicate system. It is found that, of each of these parameters, only the acoustic velocity is less than that of pure silica. The effect of temperature and strain on the acoustic velocity also is determined by utilizing estimates of the strain- and thermo-optic coefficients. The dependencies are found to have signs opposite to those of silica, thus suggesting both Brillouin-frequency a-thermal and a-tensic binary compositions. Via the estimate of the strain-optic coefficient and data found in the literature, the Pockels' photoelastic constant p(12) is estimated, and both a calculation and measured estimate of the Brillouin gain versus baria content are presented. Such novel fibers incorporating the unique properties of baria could be of great utility for narrow linewidth fiber lasers, high power passive components (such as couplers and combiners), and Brillouin-based sensor systems.

Secretory phospholipase Pla2g2a confers resistance to intestinal tumorigenesis.

Individuals inheriting the same mutation predisposing to cancer may show very different outcomes, ranging from early aggressive cancer to disease-free survival. Experimental mouse models can provide a powerful tool to identify factors in the environment and genetic background that account for such modifications. The Min mouse strain, in which the ApcMin mutation disrupts the mouse homologue of the human familial polyposis gene, develops intestinal neoplasms whose multiplicity is strongly affected by genetic background. We previously mapped a strong modifier locus, Mom1 (modifier of Min-1), to a 4-cM region on mouse chromosome 4 containing a candidate gene Pla2g2a encoding a secretory phospholipase. Here, we report that a cosmid transgene overexpressing Pla2g2a caused a reduction in tumour multiplicity and size, comparable to that conferred by a single copy of the resistance allele of Mom1. These results offer strong evidence that this secretory phospholipase can provide active tumour resistance. The association of Pla2g2a with Mom1 thus withstands a strong functional test and is likely to represent the successful identification of a polymorphic quantitative trait locus in mammals.

The DAZ gene cluster on the human Y chromosome arose from an autosomal gene that was transposed, repeatedly amplified and pruned.

It is widely believed that most or all Y-chromosomal genes were once shared with the X chromosome. The DAZ gene is a candidate for the human Y-chromosomal Azoospermia Factor (AZF). We report multiple copies of DAZ (> 99% identical in DNA sequence) clustered in the AZF region and a functional DAZ homologue (DAZH) on human chromosome 3. The entire gene family appears to be expressed in germ cells. Sequence analysis indicates that the Y-chromosomal DAZ cluster arose during primate evolution by (i) transposing the autosomal gene to the Y, (ii) amplifying and pruning exons within the transposed gene and (iii) amplifying the modified gene. These results challenge prevailing views of sex chromosome evolution, suggesting that acquisition of autosomal fertility genes is an important process in Y chromosome evolution.

Sequential measurement of the neurosensory retina in hypertensive disorders of pregnancy: a model of microvascular injury in hypertensive emergency.

Optical coherence tomography of the eye suggests the retina thins in normal pregnancy. Our objectives were to confirm and extend these observations to women with hypertensive disorders of pregnancy (HDP). Maternal demographics, clinical/laboratory findings and measurements of macular thickness were repeatedly collected at gestational ages <20 weeks, 20-weeks to delivery, at delivery and postpartum. The primary outcome was the change in macular thickness from non-pregnant dimensions in women with incident HDP compared to non-hypertensive pregnant controls. Secondary outcomes were the relationship(s) between mean arterial pressure (MAP) and macular response. Data show macular thicknesses diminished at <20 weeks gestation in each of 27 pregnancies ending in HDP (mean 3.94 µm; 95% CI 4.66, 3.21) and 11 controls (mean 3.92 µm; 5.05, 2.79; P < 0.001 versus non-pregnant dimensions in both; P = 0.983 HDP versus controls). This thinning response continued to delivery in all controls and in 7 women with HDP superimposed on chronic hypertension. Macular thinning was lost after 20 weeks gestation in the other 20 women with HDP. MAP at loss of macular thinning in women without prior hypertension (n = 12) was identical to MAP at enrollment. However, mean MAP subsequently rose 19 mmHg (15, 22) leading to de novo HDP in all 12 women. Loss of thinning leading to a rise in MAP was also observed in 8 of 15 women with HDP superimposed on chronic hypertension. We conclude the macula thins in most women in early pregnancy. Those who lose this early macular thinning response often develop blood pressure elevations leading to HDP.

Longitudinally-graded optical fibers.

Optical fibers have become ubiquitous tools for the creation, propagation, manipulation, and detection of light. However, while the intensity of light propagating through the fiber can increase or decrease along the length through amplification or attenuation, respectively, the properties of the fiber itself generally do not, thus removing an opportunity to further control the behavior of light and performance of fiber-based devices. Shown here are optical fibers that exhibit significant changes in their longitudinal optical properties, specifically a tailored longitudinal numerical aperture change of about 12% over less than 20 meters of length. This is about 1900 times greater than previously reported. The Brillouin gain coefficient was found to decrease by over 6 dB relative to a standard commercial single mode fiber. Next generation analogs are expected to exhibit more than a 10 dB reduction in SBS gain using larger, yet still reasonably manufacturable gradients over practical lengths.

Linkage of oxygen deficiency defects and rare earth concentrations in silica glass optical fiber probed by ultraviolet absorption and laser excitation spectroscopy.

Ultraviolet absorption measurements and laser excitation spectroscopy in the vicinity of 248 nm provide compelling evidence for linkages between the oxygen deficiency center (ODC) and rare earth concentrations in Yb and Er-doped glass optical fibers. Investigations of YAG-derived and solution-doped glass fibers are described. For both Yb and Er-doped fibers, the dependence of Type II ODC absorption on the rare earth number density is approximately linear, but the magnitude of the effect is greater for Yb-doped fibers. Furthermore, laser excitation spectra demonstrate unambiguously the existence of an energy transfer mechanism coupling an ODC with Yb(3+). Photopumping glass fibers with a Ti:sapphire laser/optical parametric amplifier system, tunable over the 225-265 nm region, or with a KrF laser at 248.4 nm show: 1) emission features in the 200-1100 nm interval attributable only to the ODC (Type II) defect or Yb(3+), and 2) the excitation spectra for ODC (II) emission at ~280 nm and Yb(3+) fluorescence (λ ~1.03 µm) to be, within experimental uncertainty, identical. The latter demonstrates that, when irradiating Yb-doped silica fibers between ~240 and 255 nm, the ODC (II) defect is at least the primary precursor to Yb(3+) emission. Consistent with previous reports in the literature, the data show the ODC (II) absorption spectrum to have a peak wavelength and breadth of ~246 nm and ~19 nm (FWHM). Experiments also reveal that, in the absence of Yb, incorporating either Al(2)O(3) or Y(2)O(3) into glass fibers has a negligible impact on the ODC concentration. Not only do the data reported here demonstrate the relationship between the ODC (II) number density and the Yb doping concentration, but they also suggest that the appearance of ODC defects in the fiber is associated with the introduction of Yb and the process by which the fiber is formed.

Plasma uric acid remains a marker of poor outcome in hypertensive pregnancy: a retrospective cohort study.

OBJECTIVE: To examine the relationship between hyperuricaemia, haemoconcentration and maternal and fetal outcomes in hypertensive pregnancies. DESIGN: Retrospective analysis of a database of hypertensive pregnancies. SETTING: St George Hospital, a major obstetric unit in Australia. POPULATION: A cohort of 1880 pregnant women without underlying hypertension or renal disease, referred for management of pre-eclampsia or gestational hypertension. METHODS: Demographic, clinical and biochemical data at time of referral and delivery were collected for each pregnancy. Women were grouped according to diagnosis (pre-eclampsia or gestational hypertension) and logistic regression analysis was used to determine the relationship between uric acid, haemoglobin, haematocrit and adverse outcomes; an α level of P < 0.01 was used for statistical significance. MAIN OUTCOME MEASURES: Composites of adverse maternal and fetal outcomes. RESULTS: In women with 'benign' GH (without proteinuria or any other maternal clinical feature of pre-eclampsia) gestation-corrected hyperuricaemia was associated with increased risk of a small-for-gestational-age infant (OR 2.5; 95% CI 1.3-4.8) and prematurity (OR 3.2; 95% CI 1.4-7.2), but not with adverse maternal outcome. In the whole cohort of hypertensive pregnant women (those with pre-eclampsia or gestational hypertension) the risk of adverse maternal outcome (OR 2.0; 95% CI 1.6-2.4) and adverse fetal outcome (OR 1.8; 95% CI 1.5-2.1) increased with increasing concentration of uric acid. Hyperuricaemia corrected for gestation provided additional strength to these associations. Haemoglobin and haematocrit were not associated with adverse pregnancy outcome. CONCLUSIONS: Hyperuricaemia in hypertensive pregnancy remains an important finding because it identifies women at increased risk of adverse maternal and particularly fetal outcome; the latter, even in women with gestational hypertension without any other feature of pre-eclampsia.

Silica-clad crystalline germanium core optical fibers.

Silica-clad optical fibers comprising a core of crystalline germanium were drawn using a molten core technique. With respect to previous fibers drawn using a borosilicate cladding, the present fibers exhibit negligible oxygen despite being fabricated at more than twice the melting point of the germanium. The counterintuitive result of less oxygen when the fiber is drawn at a higher temperatures is discussed. The measured propagation loss for the fiber was 0.7 dB/cm at 3.39 µm, which is the lowest loss reported to date.

Susceptibility to Laurel Wilt and Disease Incidence in Two Rare Plant Species, Pondberry and Pondspice.

Laurel wilt, caused by Raffaelea lauricola, has been responsible for extensive losses of redbay (Persea borbonia) in South Carolina and Georgia since 2003. Symptoms of the disease have been noted in other species of the Lauraceae such as the federally endangered pondberry (Lindera melissifolia) and the threatened pondspice (Litsea aestivalis). Pondberry and pondspice seedlings were inoculated with R. lauricola from redbay, and both species proved highly susceptible to laurel wilt. Field assessments found substantial mortality of pondberry and pondspice, but in many cases the losses were not attributable to laurel wilt. R. lauricola was isolated from only 4 of 29 symptomatic pondberry plants at one site, but the fungus was not recovered from three plants at another site. R. lauricola was isolated from one of two symptomatic pondspice plants at one site, and from five of 11 plants at another site, but not from any plant at a third site. Insect bore holes, similar to those produced by Xyleborus glabratus (the vector of laurel wilt), were found in some pondberry and pondspice stems, but adults were not found. Damage caused by Xylosandrus compactus was found in pondberry stems, but this ambrosia beetle does not appear to be a vector of R. lauricola. Xyleborinus saxeseni adults were found in a dying pondspice with laurel wilt, and R. lauricola was recovered from two of three adults. Isolates of R. lauricola from pondberry, pondspice, and X. saxeseni had rDNA sequences that were identical to previously characterized isolates, and inoculation tests confirmed that they were pathogenic to redbay. Because pondberry and pondspice tend to be shrubby plants with small stem diameters, these species may not be frequently attacked by X. glabratus unless in close proximity to larger diameter redbay.

Effectiveness of simulation-based training for obstetric internal medicine: Impact of cognitive load and emotions on knowledge acquisition and retention.

BACKGROUND: Simulation-based training's impact on learning outcomes may be related to cognitive load or emotions during training. We evaluated the association of validated measures of cognitive load and emotion with learning outcomes in simulation-based obstetric internal medicine cases. METHODS: All internal medicine learners (n = 15) who completed the knowledge test pre-training, post-training (knowledge acquisition), and at 3-6 months (knowledge retention) for all three simulation cases were included. RESULTS: Mean knowledge scores differed over time in all three cases (p < 0.0001 for all). Knowledge retention scores were significantly higher only for cases 1 and 3. Cognitive load associated with frustration was positively associated with knowledge acquisition for case 2 (beta = 5.18, P = 0.007), while excitement was negatively associated with knowledge retention in case 1 (beta = -33.07, p = 0.04). CONCLUSION: Simulation-based education for obstetric internal medicine can be effective in select cases. Attention to cognitive load and emotion may optimize learning outcomes.