Investigation of ultrafast demagnetization and cubic optical nonlinearity of Ni in the polar geometry

Copyright © 2004 American Institute of PhysicsFemtosecond optical pump-probe experiments were performed upon a Ni(720 Å)/Si(100) sample in the polar geometry with the pump beam close to normal incidence. A signal due to the ultrafast demagnetization effect was observed when the pump pulse was linearly polarized. When the pump was elliptically polarized, additional peaks were observed at zero time delay, resulting from the specular inverse Faraday effect (SIFE) and the specular optical Kerr effect (SOKE). By comparing measurements made with different pump helicities, the SIFE and SOKE peaks and the demagnetization signal were found to superpose in a linear fashion. From the dependence of the peak height upon the pump polarization, values of χxxyy=(1−3i)×10−10 rad cm3 erg−1 and χxyyx=(−9+2i)×10−12 rad cm3 erg−1 were deduced for the nonvanishing components of the local cubic susceptibility tensor. For applied fields less than the saturation value, the sudden reduction of the thin film demagnetizing field leads to an imbalance of the torques acting upon the magnetization, causing it to precess

Updated adolescent diagnostic criteria for polycystic ovary syndrome: impact on prevalence and longitudinal body mass index trajectories from birth to adulthood

Background: Polycystic ovary syndrome (PCOS) is challenging to diagnose. While the 2003 Rotterdam criteria are widely used for adults, the 2018 international PCOS guideline recommended updated Rotterdam criteria with both hyperandrogenism and oligo-anovulation for adolescents based on evidence-informed expert consensus. This study compared the prevalence of PCOS using updated and original Rotterdam criteria in community-based adolescents and explored long-term body mass index (BMI) trajectories across different diagnostic phenotypes. Methods: Overall, 227 postmenarchal adolescent females from the prospective cohort Raine Study undertook comprehensive PCOS assessment at age 14–16 years. Detailed anthropometric measurements were collected from birth until age 22 years. Cross-sectional and longitudinal BMI were analyzed using t tests and generalized estimating equations. Results: PCOS was diagnosed in 66 (29.1%) participants using original criteria versus 37 (16.3%) participants using updated Rotterdam criteria. Using updated criteria, participants with PCOS had higher BMI than participants without PCOS from prepubertal. Only the phenotype meeting the updated criteria was significantly associated with higher long-term BMI gain whereas other PCOS phenotypes had similar BMI trajectories to participants without PCOS (p < 0.001). Conclusions: The use of the 2018 updated Rotterdam criteria reduces over-diagnosis of PCOS in adolescents and identifies those at the greatest risk of long-term weight gain, a key contributor to disease severity and long-term health implications. The BMI trajectories of females with PCOS on updated criteria diverge prepubertally compared to those without PCOS. This work supports targeting adolescents diagnosed with PCOS on the 2018 updated criteria for early lifestyle interventions to prevent long-term health complications.Chau Thien Tay, Roger J. Hart, Martha Hickey, Lisa J. Moran, Arul Earnest, Dorota A. Doherty, Helena J. Teede and Anju E. Joha

A single fast radio burst localized to a massive galaxy at cosmological distance

Fast radio bursts (FRBs) are brief radio emissions from distant astronomical sources. Some are known to repeat, but most are single bursts. Nonrepeating FRB observations have had insufficient positional accuracy to localize them to an individual host galaxy. We report the interferometric localization of the single-pulse FRB 180924 to a position 4 kiloparsecs from the center of a luminous galaxy at redshift 0.3214. The burst has not been observed to repeat. The properties of the burst and its host are markedly different from those of the only other accurately localized FRB source. The integrated electron column density along the line of sight closely matches models of the intergalactic medium, indicating that some FRBs are clean probes of the baryonic component of the cosmic web

Advances in large-scale mudflat surveying: The Roebuck Bay and Eighty Mile Beach, Western Australia examples

The shores of Roebuck Bay and Eighty Mile Beach in northwestern Australia are amongst the richest known intertidal mudflats worldwide. They are both listed as Wetlands of International Importance under the Ramsar Convention, primarily because of the high numbers of shorebirds that migrate to and from these sites every year. There are only a dozen or so areas in the world with extensive intertidal flats rich in shorebirds.Shorebird studies by a collaboration between The Department of Environment and Conservation, The University of Western Australia, The Royal Netherlands Institute for Sea Research, Central Washington University, Broome Bird Observatory, and local community volunteers in northwestern Australia have focused on understanding the geological and biological processes of coastal tidal mudflats. Studies have established that invertebrates are abundant and they are used for feeding by resident and migratory shorebirds.In addition to requiring equipment, software, and considerable organization, these labor intensive studies were only possible with the assistance of large numbers of community volunteers, professionals, and donated equipmen

Associations between prenatal exposure to phthalates and timing of menarche and growth and adiposity into Adulthood: A Twenty-Years Birth Cohort Study

Phthalates are ubiquitous environmental chemicals with endocrine disrupting properties and potentially obesogenic effects. We hypothesised that antenatal phthalate exposure may influence growth and adiposity patterns in girls through childhood into adolescence. Among 1342 Raine Study singleton females, 462 had maternal serum and at least one outcome available up to 20 years of age. Individuals’ maternal serum collected at 18 and 34 weeks gestation was pooled and analyzed for concentrations of 32 metabolites of 15 phthalate diesters. Cox regression and linear models were used to determine associations between maternal phthalate levels and age at menarche, change in height and weight z-scores between birth and two years, height from birth to 20 years, BMI from two to 20 years, deviation from mid-parental height at age 20 and DEXA scan measures at age 20. Weak negative associations were detected with some phthalate metabolites and change in height and weight z-score during infancy. Weak positive associations between some of the high molecular weight phthalate metabolites and height z-score were detected during childhood. While still within the normal range, age at menarche was slightly delayed in girls with higher prenatal exposure to the higher molecular weight phthalate metabolites. We derived some associations between prenatal phthalate exposure with early growth patterns and age at menarche

An infrared-radio simulation of the extragalactic sky: from the Square Kilometre Array to Herschel

The definitive version can be found at: http://www3.interscience.wiley.com/ Copyright Royal Astronomical SocietyTo exploit synergies between the Herschel Space Observatory and next generation radio facilities, we have extended the semi-empirical extragalactic radio continuum simulation of Wilman et al. to the mid- and far-infrared. Here, we describe the assignment of infrared spectral energy distributions (SEDs) to the star-forming galaxies and active galactic nuclei, using Spitzer 24, 70 and 160 mu m and SCUBA 850 mu m survey results as the main constraints. Star-forming galaxies dominate the source counts, and a model in which their far-infrared-radio correlation and infrared SED assignment procedure are invariant with redshift underpredicts the observed 24 and 70 mu m source counts. The 70 mu m deficit can be eliminated if the star-forming galaxies undergo stronger luminosity evolution than originally assumed for the radio simulation, a requirement which may be partially ascribed to known non-linearity in the far-infrared-radio correlation at low luminosity if it evolves with redshift. At 24 mu m, the shortfall is reduced if the star-forming galaxies develop SEDs with cooler dust and correspondingly stronger polycyclic aromatic hydrocarbon emission features with increasing redshift at a given far-infrared luminosity, but this trend may reverse at z > 1 in order not to overproduce the submillimetre source counts. The resulting model compares favourably with recent Balloon-borne Large Aperture Submillimetre Telescope (BLAST) results, and we have extended the simulation data base to aid the interpretation of Herschel surveys. Such comparisons may also facilitate further model refinement and revised predictions for the Square Kilometre Array and its precursors.Peer reviewe