Macquarie University

About: Macquarie University is a education organization based out in Sydney, New South Wales, Australia. It is known for research contribution in the topics: Population & Laser. The organization has 14075 authors who have published 47673 publications receiving 1416184 citations. The organization is also known as: Macquarie uni.

THE MOST LUMINOUS z ∼ 9-10 GALAXY CANDIDATES YET FOUND: THE LUMINOSITY FUNCTION, COSMIC STAR-FORMATION RATE, AND THE FIRST MASS DENSITY ESTIMATE AT 500 Myr*

Abstract: We present the discovery of four surprisingly bright (H160 � 26 27 mag AB) galaxy candidates at z � 9 10 in the complete HST CANDELS WFC3/IR GOODS-N imaging data, doubling the number of z � 10 galaxy candidates that are known, just �500 Myr after the Big Bang. Two similarly bright sources are also detected in a systematic re-analysis of the GOODS-S data set. Three of the four galaxies in GOODS-N are significantly detected at 4.5 6.2� in the very deep Spitzer/IRAC 4.5µm data, as is one of the GOODS-S candidates. Furthermore, the brightest of our candidates (at z = 10.2 ± 0.4) is robustly detected also at 3.6µm (6.9�), revealing a flat UV spectral energy distribution with a slope � = 2.0±0.2, consistent with demonstrated trends with luminosity at high redshift. The abundance of such luminous candidates suggests that the luminosity function evolves more significantly in �∗ than in L∗ at z & 8 with a higher number density of bright sources than previously expected. Despite the discovery of these luminous candidates, the cosmic star formation rate density for galaxies with SFR > 0.7 M⊙ yr −1 shows an order-of-magnitude increase in only 170 Myr from z � 10 to z � 8, consistent with previous results given the dominance of low-luminosity sources to the total SFR density. Based on the IRAC detections, we derive galaxy stellar masses at z � 10, finding that these luminous objects are typically 10 9 M⊙. This allows for a first estimate of the cosmic stellar mass density at z � 10 resulting in log10 �∗ = 4.7 +0.5 −0.8 M⊙ Mpc −3 for galaxies brighter than MUV � 18. The remarkable brightness, and hence luminosity, of these z � 9 10 candidates highlights the opportunity for deep spectroscopy to determine their redshift and nature, demonstrates the value of additional search fields covering a wider area to understand star-formation in the very early universe, and highlights the opportunities for JWST to map the buildup of galaxies at redshifts much earlier than z � 10. Subject headings: galaxies: evolution — galaxies: high-redshift — galaxies: luminosity function

Intensity of dementia through latent variable modelling (I-DeLV) in the AIBL cohort

Abstract: 69% of Mild Cognitively Impaired and 96% of AD. Conclusions: The described models provide accurate estimations of NAB based on demographic corrected cognitive test scores. If NAB is a predictor for progression to AD and given such models can accurately predict NAB, it follows that this work may lead to an effective and economical screen for early detection of individuals at risk of developing AD, in-turn providing justification for further confirmatory tests (e.g. PET) or to identify suitable participants for intervention or therapeutic trials.

Sexual negotiation in the AIDS era: negotiated safety revisited.

Abstract: Objective: To test the safety of the 'negotiated safety' strategy - the strategy of dispensing with condoms within HIV-seronegative concordant regular sexual relationships under certain conditions. Method: Data from a recently recruited cohort of homosexually active men (Sydney Men and Sexual Health cohort, n = 1037) are used to revisit negotiated safety. The men were surveyed using a structured questionnaire and questions addressing their sexual relationships and practice, their own and their regular partner's serostatus, agreements entered into by the men concerning sexual practice within and outside their regular relationship, and contextual and demographic variables. Results: The findings indicate that a significant number of men used negotiated safety as an HIV prevention strategy. In the 6 months prior to interview, of the 181 men in seroconcordant HIV-negative regular relationships, 62% had engaged in unprotected anal intercourse within their relationship, and 91% (165 men) had not engaged in unprotected anal intercourse outside their relationship. Of these 165 men, 82% had negotiated agreements about sex outside their relationship. The safety of negotiation was dependent not only on seroconcordance but also on the presence of an agreement; 82% of the men who had not engaged in unprotected anal intercourse outside their regular relationship had entered into an agreement with their partner, whereas only 56% of those who had engaged in unprotected anal intercourse had an agreement. The safety of negotiation was also related to the nature of the safety agreement reached between the men and on the acceptability of condoms. Agreements between HIV-negative seroconcordant regular partners prohibiting anal intercourse with casual partners or any form of sex with a casual partner were typically complied with, and men who had such negotiated agreements were at low risk of HIV infection. Conclusions: The adoption of the strategy of negotiated safety among men in HIV-seronegative regular relationships may help such men sustain the safety of their sexual practice.

Why is the choice of future climate scenarios for species distribution modelling important

Abstract: Species distribution models (SDMs) are common tools for assessing the potential impact of climate change on species ranges. Uncertainty in SDM output occurs due to differences among alternate models, species characteristics and scenarios of future climate. While considerable effort is being devoted to identifying and quantifying the first two sources of variation, a greater understanding of climate scenarios and how they affect SDM output is also needed. Climate models are complex tools: variability occurs among alternate simulations, and no single 'best' model exists. The selection of climate scenarios for impacts assessments should not be undertaken arbitrarily - strengths and weakness of different climate models should be considered. In this paper, we provide bioclimatic modellers with an overview of emissions scenarios and climate models, discuss uncertainty surrounding projections of future climate and suggest steps that can be taken to reduce and communicate climate scenario-related uncertainty in assessments of future species responses to climate change.