On the Relation between Solar Activity and Clear-Sky Terrestrial Irradiance

The Mauna Loa Observatory record of direct-beam solar irradiance measurements for the years 1958-2010 is analysed to investigate the variation of clear-sky terrestrial insolation with solar activity over more than four solar cycles. The raw irradiance data exhibit a marked seasonal cycle, extended periods of lower irradiance due to emissions of volcanic aerosols, and a long-term decrease in atmospheric transmission independent of solar activity. After correcting for these effects, it is found that clear-sky terrestrial irradiance typically varies by about 0.2 +/- 0.1% over the course of the solar cycle, a change of the same order of magnitude as the variations of the total solar irradiance above the atmosphere. An investigation of changes in the clear-sky atmospheric transmission fails to find a significant trend with sunspot number. Hence there is no evidence for a yet unknown effect amplifying variations of clear-sky irradiance with solar activity.Comment: 16 pages, 7 figures, in press at Solar Physics; minor changes to the text to match final published versio

Non-Invasive Mouse Models of Post-Traumatic Osteoarthritis

SummaryAnimal models of osteoarthritis (OA) are essential tools for investigating the development of the disease on a more rapid timeline than human OA. Mice are particularly useful due to the plethora of genetically modified or inbred mouse strains available. The majority of available mouse models of OA use a joint injury or other acute insult to initiate joint degeneration, representing post-traumatic osteoarthritis (PTOA). However, no consensus exists on which injury methods are most translatable to human OA. Currently, surgical injury methods are most commonly used for studies of OA in mice; however, these methods may have confounding effects due to the surgical/invasive injury procedure itself, rather than the targeted joint injury. Non-invasive injury methods avoid this complication by mechanically inducing a joint injury externally, without breaking the skin or disrupting the joint. In this regard, non-invasive injury models may be crucial for investigating early adaptive processes initiated at the time of injury, and may be more representative of human OA in which injury is induced mechanically. A small number of non-invasive mouse models of PTOA have been described within the last few years, including intra-articular fracture of tibial subchondral bone, cyclic tibial compression loading of articular cartilage, and anterior cruciate ligament (ACL) rupture via tibial compression overload. This review describes the methods used to induce joint injury in each of these non-invasive models, and presents the findings of studies utilizing these models. Altogether, these non-invasive mouse models represent a unique and important spectrum of animal models for studying different aspects of PTOA

Comorbid diagnoses for youth at clinical high risk of psychosis

Several studies have demonstrated that youth at clinical high risk (CHR) of developing psychosis have a high prevalence of comorbid psychiatric disorders. Less is known about the impact of comorbid diagnoses on later conversion to psychosis and the change over time. The aim of this study was to determine the frequency and distribution of psychiatric diagnoses at baseline and over time in the North American Prodrome Longitudinal Study (NAPLS 2) and the role of comorbid diagnoses in conversion to psychosis. The NAPLS 2 sample consisted of 744 CHR youth and 276 healthy controls. Only 21% of the CHR group did not have a comorbid diagnosis with many have 2–3 DSM-IV comorbid diagnoses. The most common diagnoses were anxiety and depressive disorders, which did improve over time. The only diagnosis at baseline that differentiated the converters from the non-converters was cannabis misuse. Comorbidity, except for cannabis use, was essentially independent of clinical outcome. It is possible that those with comorbid diagnoses are preferentially the help-seeking individuals that present for help in our clinics and research projects and that those who are at risk but do not have a comorbid diagnosis may not be seeking help in the prodromal phase

Stylized facts of intraday precious metals

This paper examines the stylized facts, correlation and interaction between volatility and returns at the 5-minute frequency for gold, silver, platinum and palladium from May 2000 to April 2015. We study the full sample period, as well as three subsamples to determine how high-frequency data of precious metals have developed over time. We find that over the full sample, the number of trades has increased substantially over time for each precious metal, while the bid-ask spread has narrowed over time, indicating an increase in liquidity and price efficiency. We also find strong evidence of periodicity in returns, volatility, volume and bid- ask spread. Returns and volume both experience strong intraday periodicity linked to the opening and closing of major markets around the world while the bid-ask spread is at its low- est when European markets are open. We also show a bilateral Granger causality between returns and volatility of each precious metal, which holds for the vast majority subsamples

Energetic particle influence on the Earth's atmosphere

This manuscript gives an up-to-date and comprehensive overview of the effects of energetic particle precipitation (EPP) onto the whole atmosphere, from the lower thermosphere/mesosphere through the stratosphere and troposphere, to the surface. The paper summarizes the different sources and energies of particles, principally galactic cosmic rays (GCRs), solar energetic particles (SEPs) and energetic electron precipitation (EEP). All the proposed mechanisms by which EPP can affect the atmosphere are discussed, including chemical changes in the upper atmosphere and lower thermosphere, chemistry-dynamics feedbacks, the global electric circuit and cloud formation. The role of energetic particles in Earth’s atmosphere is a multi-disciplinary problem that requires expertise from a range of scientific backgrounds. To assist with this synergy, summary tables are provided, which are intended to evaluate the level of current knowledge of the effects of energetic particles on processes in the entire atmosphere

Data from commercial sheep producers shows that lambing ewes in larger mobs and at higher stocking rates reduces the survival of their lambs

Higher stocking rates of lambing ewes have been associated with poorer ewe-lamb behaviour and lamb survival. This study tested the hypothesis that increasing the mob size and stocking rate of lambing ewes on commercial farms will reduce the survival of their lambs. Data were collected from 66 producers in Australia for Experiment one and 22 producers in New Zealand for Experiment two. Survival of single- and twin-born lambs decreased by 1.4% and 3.5% per extra 100 ewes in the mob, regardless of breed, in Experiment one. The survival of Merino lambs in Experiment two decreased by 0.9% per extra 100 ewes in the mob, regardless of birth type. Increasing stocking rate by 1 ewe/ha also decreased lamb survival by 0.7% in Experiment one. However, this was not evident in Experiment two. These findings highlight the scope to optimise ewe mob size and stocking rate at lambing to improve lamb survival

Surface Structure, Lattice Dynamics, and Raman Spectroscopy of Sulphur Passivated InP(001)

The sulphur-passivated InP(001) surface is studied theoretically using density-functional methods and experimentally using Raman spectroscopy. The lowest energy structure is a very striking (2 72) reconstruction with the S atoms displaced from the bridge sites to form short and long dimers, belonging to two distinct sublayers. The underlying In layer remains integral, but the P layer below it also splits into two sublayers. This structure is used to calculate the [001] interplanar force constants and the backscattering Raman spectrum. Two peaks arising from surface-layer vibrations, predicted to be at 190 and 257 cm-1, are observed experimentally.Peer reviewed: YesNRC publication: Ye