Thomas Young's contribution to visual optics : the Bakerian lecture "On the mechanism of the eye"

Thomas Young (1773-1829) carried out major pioneering work in many different subjects. In 1800 he gave the Bakerian Lecture of the Royal Society on the topic of the “mechanism of the eye”: this was published in the following year (Young, 1801). Young used his own design of optometer to measure refraction and accommodation, and discovered his own astigmatism. He considered the different possible origins of accommodation and confirmed that it was due to change in shape of the lens rather than to change in shape of the cornea or an increase in axial length. However, the paper also dealt with many other aspects of visual and ophthalmic optics, such as biometric parameters, peripheral refraction, longitudinal chromatic aberration, depth-of-focus and instrument myopia. These aspects of the paper have previously received little attention. We now give detailed consideration to these and other less-familiar features of Young’s work and conclude that his studies remain relevant to many of the topics which currently engage visual scientists.

Thomas Young’s contributions to geometrical optics

In addition to his work on physical optics, Thomas Young (1773-1829) made several contributions to geometrical optics, most of which received little recognition in his time or since. We describe and assess some of these contributions: Young’s construction (the basis for much of his geometric work), paraxial refraction equations, oblique astigmatism and field curvature, and gradient-index optics.

Thomas Young’s investigations in gradient-index optics

Purpose: James Clerk Maxwell is usually recognized as being the first, in 1854, to consider using inhomogeneous media in optical systems. However, some fifty years earlier Thomas Young, stimulated by his interest in the optics of the eye and accommodation, had already modeled some applications of gradient-index optics. These applications included using an axial gradient to provide spherical aberration-free optics and a spherical gradient to describe the optics of the atmosphere and the eye lens. We evaluated Young’s contributions. Method: We attempted to derive Young’s equations for axial and spherical refractive index gradients. Raytracing was used to confirm accuracy of formula. Results: We did not confirm Young’s equation for the axial gradient to provide aberration-free optics, but derived a slightly different equation. We confirmed the correctness of his equations for deviation of rays in a spherical gradient index and for the focal length of a lens with a nucleus of fixed index surrounded by a cortex of reducing index towards the edge. Young claimed that the equation for focal length applied to a lens with part of the constant index nucleus of the sphere removed, such that the loss of focal length was a quarter of the thickness removed, but this is not strictly correct. Conclusion: Young’s theoretical work in gradient-index optics received no acknowledgement from either his contemporaries or later authors. While his model of the eye lens is not an accurate physiological description of the human lens, with the index reducing least quickly at the edge, it represented a bold attempt to approximate the characteristics of the lens. Thomas Young’s work deserves wider recognition.

David M. Thomas : a party disguised as work or work disguised as a party

This article discusses David M. Thomas' 2012 exhibition at Boxcopy. Thomas' exhibition conflates the space of the studio with that of the gallery. In doing so, he draws out complex relationships between production and presentation, subjectivity and sociality. This article focuses on these aspects of Thomas' creative exploration of identity and its mutability through art making.

Years lived with disability (YLDs) for 1160 sequelae of 289 diseases and injuries 1990–2010 : a systematic analysis for the Global Burden of Disease Study 2010

Background Non-fatal health outcomes from diseases and injuries are a crucial consideration in the promotion and monitoring of individual and population health. The Global Burden of Disease (GBD) studies done in 1990 and 2000 have been the only studies to quantify non-fatal health outcomes across an exhaustive set of disorders at the global and regional level. Neither effort quantified uncertainty in prevalence or years lived with disability (YLDs). Methods Of the 291 diseases and injuries in the GBD cause list, 289 cause disability. For 1160 sequelae of the 289 diseases and injuries, we undertook a systematic analysis of prevalence, incidence, remission, duration, and excess mortality. Sources included published studies, case notification, population-based cancer registries, other disease registries, antenatal clinic serosurveillance, hospital discharge data, ambulatory care data, household surveys, other surveys, and cohort studies. For most sequelae, we used a Bayesian meta-regression method, DisMod-MR, designed to address key limitations in descriptive epidemiological data, including missing data, inconsistency, and large methodological variation between data sources. For some disorders, we used natural history models, geospatial models, back-calculation models (models calculating incidence from population mortality rates and case fatality), or registration completeness models (models adjusting for incomplete registration with health-system access and other covariates). Disability weights for 220 unique health states were used to capture the severity of health loss. YLDs by cause at age, sex, country, and year levels were adjusted for comorbidity with simulation methods. We included uncertainty estimates at all stages of the analysis. Findings Global prevalence for all ages combined in 2010 across the 1160 sequelae ranged from fewer than one case per 1 million people to 350 000 cases per 1 million people. Prevalence and severity of health loss were weakly correlated (correlation coefficient −0·37). In 2010, there were 777 million YLDs from all causes, up from 583 million in 1990. The main contributors to global YLDs were mental and behavioural disorders, musculoskeletal disorders, and diabetes or endocrine diseases. The leading specific causes of YLDs were much the same in 2010 as they were in 1990: low back pain, major depressive disorder, iron-deficiency anaemia, neck pain, chronic obstructive pulmonary disease, anxiety disorders, migraine, diabetes, and falls. Age-specific prevalence of YLDs increased with age in all regions and has decreased slightly from 1990 to 2010. Regional patterns of the leading causes of YLDs were more similar compared with years of life lost due to premature mortality. Neglected tropical diseases, HIV/AIDS, tuberculosis, malaria, and anaemia were important causes of YLDs in sub-Saharan Africa. Interpretation Rates of YLDs per 100 000 people have remained largely constant over time but rise steadily with age. Population growth and ageing have increased YLD numbers and crude rates over the past two decades. Prevalences of the most common causes of YLDs, such as mental and behavioural disorders and musculoskeletal disorders, have not decreased. Health systems will need to address the needs of the rising numbers of individuals with a range of disorders that largely cause disability but not mortality. Quantification of the burden of non-fatal health outcomes will be crucial to understand how well health systems are responding to these challenges. Effective and affordable strategies to deal with this rising burden are an urgent priority for health systems in most parts of the world. Funding Bill & Melinda Gates Foundation.

Jean Baptiste Francois Pompallier, Thomas Arnold and Julian Edmund Tenison Woods and their contribution to the formation and development of Catholic schooling in Australasia

Histories of Catholic education have received little attention by Church historians and are usually written by members of the Catholic clergy, with a strong emphasis placed on the spiritual and building accomplishments of the bishops. This thesis examines the provision of Catholic Education in Australasia, with a focus on the contribution of three men, Jean Baptiste Francois Pompallier, Thomas Arnold and Julian Edmund Tenison Woods. These men received support from the female religious orders in the regions where they worked, frequently with little recognition or praise by Catholic Church authorities. The tenets of their faith gave Pompallier and Woods strength and reinforced their determination to succeed. Arnold, however, possessed a strong desire to change society. All three believed in the desirability of providing Catholic schooling for the poor, with the curriculum facilitating the acquisition of socially desirable values and traits, including obedience, honesty, moral respectability and a strong adherence to Catholic religious values. The beneficiaries included society, future employers, the Church, the children and their parents. With the exception of promoting distinctly Catholic religious values, Roman Catholic schools and National schools in Australasia shared identical objectives. Historians have neglected the contributions of these men.

Taxonomy and redescription of the Fawn Antechinus, Antechinus bellus (Thomas) (Marsupialia: Dasyuridae)

We provide a taxonomic redescription of the Fawn Antechinus, Antechinus bellus (Thomas). A. bellus is the only member of its genus to occur in Australia’s Northern Territory, where it can be found in savannah woodlands of the Top End. It is perhaps the most distinctive antechinus, and clearly distinguishable from the other 10 extant species of antechinus found in Australia: externally, A. bellus has pale body fur, white feet and large ears; A. bellus skulls have large auditory bullae and narrow interorbital width, while broadening abruptly at the molar row; mitochondrial and nuclear genes clearly dis-tinguish A. bellus from all congeners, phylogenetically positioning the Fawn Antechinus as sister to Queensland’s A. leo Van Dyck, 1980, with which it shares a curled supratragus of the external ear and a similar tropical latitudinal range.

Taxonomy and redescription of the Atherton Antechinus, Antechinus godmani (Thomas) (Marsupialia: Dasyuridae)

We provide a taxonomic redescription of the dasyurid marsupial Atherton Antechinus, Antechinus godmani (Thomas). A. godmani is only rarely encountered and limited to wet tropical rainforests of north-east Queensland, Australia, between the towns of Cardwell and Cairns (a distribution spanning 135 kilometres from north to south). The distinctive species occurs at altitudes of over 600 meters asl, in all major rainforest types, and can be found with both the northern subspecies of the Yellow-footed Antechinus, A. flavipes rubeculus Van Dyck and the Rusty Antechinus, A. adustus (Thomas). A. god-mani is clearly separated from all congeners on the basis of both morphometrics and genetics. A. godmani can be distin-guished from all extant congeners based on external morphology by a combination of large size, naked-looking tail and reddish fur on the face and head. A. godmani skulls are characteristically large, with a suite of long features: basicranium, palate, upper premolar tooth row, inter-palatal vacuity distance and dentary. Phylogenies generated from mt- and nDNA data position Antechinus godmani as monophyletic with respect to other members of the genus; A. godmani is strongly supported as the sister-group to a clade containing all other antechinus, but excluding the south-east Australian Dusky An-techinus, A. swainsonii (Waterhouse) and Swamp Antechinus, A. minimus (Geoffroy). Antechinus godmani are genetically very divergent compared to all congeners (mtDNA: range 12.9–16.3%).

Conservation genetics of the water mouse, Xeromys myoides Thomas, 1889

The water mouse, Xeromys myoides, is currently recognised as a vulnerable species in Australia, inhabiting a small number of distinct and isolated coastal regions of Queensland and the Northern Territory. An examination of the evolutionary history and contemporary influences shaping the genetic structure of this species is required to make informed conservation management decisions. Here, we report the first analysis undertaken on the phylogeography and population genetics of the water mouse across its mainland Australian distribution. Genetic diversity was assessed at two mitochondrial DNA (Cytochrome b, 1000 bp; D-loop, 400 bp) and eight microsatellite DNA loci. Very low genetic diversity was found, indicating that water mice underwent a recent expansion throughout their Australian range and constitute a single evolutionarily significant unit. Microsatellite analyses revealed that the highest genetic diversity was found in the Mackay region of central Queensland; population substructure was also identified, suggesting that local populations may be isolated in this region. Conversely, genetic diversity in the Coomera region of south-east Queensland was very low and the population in this region has experienced a significant genetic bottleneck. These results have significant implications for future management, particularly in terms of augmenting populations through translocations or reintroducing water mice in areas where they have gone extinct.

Émile Durkheim and Thomas Luckmann: Religion, spirituality and mental health

This chapter examines connections between religion, spirituality and mental health. Religion and spirituality influence the way people conceive themselves, others and the world around them, as well as how they behave – and are strongly associated with numerous mental health outcomes. Religion and spirituality therefore demand the attention of those who seek a comprehensive understanding of the factors that affect mental health. Mental health professionals are increasingly being asked to consider their clients’ religious and/or spiritual beliefs when devising their treatment plans, making the study of religion and spirituality an essential area of learning for those working in the mental health field. Initial discussion in this chapter will focus on the different approaches taken by sociologists in studying mental health. Emile Durkheim, one of the founders of sociology, proposed that religion was fundamental to societal wellbeing and was the first to demonstrate a link between religion and mental health at a population level in the late 19th century. Durkheim’s classic theory of religion, together with the work of Thomas Luckmann and other contemporary social theorists who have sought to explain widespread religious change in Western countries since World War II will be examined. Two key changes during this period are the shift away from mainstream Christian religions and the widespread embracing of ‘spirituality’ as an alternative form of religious expression. In combination, the theories of Durkheim, Luckmann and other sociologists provide a platform from which to consider reasons for variations in rates of mental health problems observed in contemporary Western societies according to people’s religious/spiritual orientation. This analysis demonstrates the relevance of both classic and contemporary sociological theories to issues confronting societies in the present day.

A comparative risk assessment of burden of disease and injury attributable to 67 risk factors and risk factor clusters in 21 regions, 1990–2010: A systematic analysis for the Global Burden of Disease Study 2010

BACKGROUND Quantification of the disease burden caused by different risks informs prevention by providing an account of health loss different to that provided by a disease-by-disease analysis. No complete revision of global disease burden caused by risk factors has been done since a comparative risk assessment in 2000, and no previous analysis has assessed changes in burden attributable to risk factors over time. METHODS We estimated deaths and disability-adjusted life years (DALYs; sum of years lived with disability [YLD] and years of life lost [YLL]) attributable to the independent effects of 67 risk factors and clusters of risk factors for 21 regions in 1990 and 2010. We estimated exposure distributions for each year, region, sex, and age group, and relative risks per unit of exposure by systematically reviewing and synthesising published and unpublished data. We used these estimates, together with estimates of cause-specific deaths and DALYs from the Global Burden of Disease Study 2010, to calculate the burden attributable to each risk factor exposure compared with the theoretical-minimum-risk exposure. We incorporated uncertainty in disease burden, relative risks, and exposures into our estimates of attributable burden. FINDINGS In 2010, the three leading risk factors for global disease burden were high blood pressure (7·0% [95% uncertainty interval 6·2-7·7] of global DALYs), tobacco smoking including second-hand smoke (6·3% [5·5-7·0]), and alcohol use (5·5% [5·0-5·9]). In 1990, the leading risks were childhood underweight (7·9% [6·8-9·4]), household air pollution from solid fuels (HAP; 7·0% [5·6-8·3]), and tobacco smoking including second-hand smoke (6·1% [5·4-6·8]). Dietary risk factors and physical inactivity collectively accounted for 10·0% (95% UI 9·2-10·8) of global DALYs in 2010, with the most prominent dietary risks being diets low in fruits and those high in sodium. Several risks that primarily affect childhood communicable diseases, including unimproved water and sanitation and childhood micronutrient deficiencies, fell in rank between 1990 and 2010, with unimproved water and sanitation accounting for 0·9% (0·4-1·6) of global DALYs in 2010. However, in most of sub-Saharan Africa childhood underweight, HAP, and non-exclusive and discontinued breastfeeding were the leading risks in 2010, while HAP was the leading risk in south Asia. The leading risk factor in Eastern Europe, most of Latin America, and southern sub-Saharan Africa in 2010 was alcohol use; in most of Asia, North Africa and Middle East, and central Europe it was high blood pressure. Despite declines, tobacco smoking including second-hand smoke remained the leading risk in high-income north America and western Europe. High body-mass index has increased globally and it is the leading risk in Australasia and southern Latin America, and also ranks high in other high-income regions, North Africa and Middle East, and Oceania. INTERPRETATION Worldwide, the contribution of different risk factors to disease burden has changed substantially, with a shift away from risks for communicable diseases in children towards those for non-communicable diseases in adults. These changes are related to the ageing population, decreased mortality among children younger than 5 years, changes in cause-of-death composition, and changes in risk factor exposures. New evidence has led to changes in the magnitude of key risks including unimproved water and sanitation, vitamin A and zinc deficiencies, and ambient particulate matter pollution. The extent to which the epidemiological shift has occurred and what the leading risks currently are varies greatly across regions. In much of sub-Saharan Africa, the leading risks are still those associated with poverty and those that affect children.

A taxonomic assessment of the Australian Dusky Antechinus Complex: A new species, the Tasman Peninsula Dusky Antechinus (Antechinus vandycki sp. nov.) and an elevation to species of the Mainland Dusky Antechinus (Antechinus swainsonii mimetes (Thomas))

In 2014, the northern outlying population of carnivorous marsupial Dusky Antechinus (Antechinus swainsonii) was nominated a new species, A. arktos. Here, we describe a further new species in the dasyurid A. swainsonii complex, which now contains five taxa. We recognise two distinct species from Tasmania, formerly represented by A. swainsonii swainsonii (Waterhouse); one species (and 2 subspecies) from mainland south-eastern Australia, formerly known as A. swainsonii mimetes (Thomas) and A. swainsonii insulanus Davison; and one species from the Tweed Caldera in mid-eastern Australia, formerly known as A. s. mimetes but recently described as A. arktos Baker, Mutton, Hines and Van Dyck. Primacy of discovery dictates the Tasmanian Dusky Antechinus A. swainsonii (Waterhouse) is nominate; the Mainland Dusky Antechinus taxa, one raised from subspecies within A. swainsonii mimetes (Thomas) is elevated to species (now A. mimetes mimetes) and the other, A. swainsonii insulanus Davison is transferred as a subspecies of A. mimetes (now A. mimetes insulanus); a species from Tasmania, the Tasman Peninsula Dusky Antechinus, is named A. vandycki sp. nov. These taxa are strongly differentiated: geographically (in allopatry), morphologically (in coat colour and craniodental features) and genetically (in mtDNA, 7.5-12.5% between species pairs).