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Walker AR, Srasuebkul P, Trollor JN, Wand APF, Draper B, Cvejic RC, Moxey A, Reppermund S. Mortality in people living with dementia who self-harmed: An Australian data linkage study. Aust N Z J Psychiatry 2024; 58:990-1000. [PMID: 39252467 PMCID: PMC11497739 DOI: 10.1177/00048674241278243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 09/11/2024]
Abstract
OBJECTIVES This study aimed to examine mortality for people living with dementia/mild cognitive impairment who self-harmed. METHODS We conducted a retrospective cohort study in New South Wales, Australia, using data ranging from 2001 to 2015. From people who accessed hospital services in the study period, we identified 154,811 people living with dementia/mild cognitive impairment, 28,972 who self-harmed and 1511 who had a record of both dementia/mild cognitive impairment and self-harm. We examined rates, causes and predictors of death for people with dementia/mild cognitive impairment and/or self-harm diagnoses using flexible parametric survival analyses. We explored rates of repeat self-harm in people living with dementia who self-harmed. RESULTS Circulatory disorders accounted for 32.0% of deaths in people with a living with dementia who self-harmed, followed by neoplasms (14.7%), and mental and behavioural disorders (9.6%). Death was more likely for someone who had self-harmed if they developed dementia/mild cognitive impairment. Predictors of death included male sex, greater physical comorbidity, a history of delirium, more previous emergency department presentations and fewer previous mental health ambulatory service days. Greater engagement with outpatient mental health services predicted a decreased likelihood of repeat self-harm. DISCUSSION We found that mortality increases when people who self-harm develop dementia. We argue post-diagnosis support offers a potential opportunity to reduce mortality rates in people with both dementia and self-harm diagnoses.
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Walker AR, Venetis CA, Opdahl S, Chambers GM, Jorm LR, Vajdic CM. Estimating the impact of bias in causal epidemiological studies: the case of health outcomes following assisted reproduction. Hum Reprod 2024; 39:869-875. [PMID: 38509860 PMCID: PMC11063565 DOI: 10.1093/humrep/deae053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Revised: 02/19/2024] [Indexed: 03/22/2024] Open
Abstract
Researchers interested in causal questions must deal with two sources of error: random error (random deviation from the true mean value of a distribution), and bias (systematic deviance from the true mean value due to extraneous factors). For some causal questions, randomization is not feasible, and observational studies are necessary. Bias poses a substantial threat to the validity of observational research and can have important consequences for health policy developed from the findings. The current piece describes bias and its sources, outlines proposed methods to estimate its impacts in an observational study, and demonstrates how these methods may be used to inform debate on the causal relationship between medically assisted reproduction (MAR) and health outcomes, using cancer as an example. In doing so, we aim to enlighten researchers who work with observational data, especially regarding the health effects of MAR and infertility, on the pitfalls of bias, and how to address them. We hope that, in combination with the provided example, we can convince readers that estimating the impact of bias in causal epidemiologic research is not only important but necessary to inform the development of robust health policy and clinical practice recommendations.
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Walker AR, Srasuebkul P, Trollor JN, Wand APF, Draper B, Cvejic RC, Moxey A, Reppermund S. Risk factors for dementia and self-harm: A linkage study. Alzheimers Dement 2023; 19:5138-5150. [PMID: 37126409 DOI: 10.1002/alz.13080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 02/22/2023] [Accepted: 03/11/2023] [Indexed: 05/02/2023]
Abstract
INTRODUCTION People living with dementia experience poor mental health and high rates of self-harm. We investigated risk factors for self-harm in people aged > 40 years living with dementia and risk factors for dementia after self-harm. METHODS Using linked hospital data from New South Wales, Australia, we defined a dementia cohort (n = 154,811) and a self-harm cohort (n = 28,972). Using survival analyses, we investigated predictors of self-harm for the dementia cohort, and predictors of dementia for the self-harm cohort. RESULTS We found self-harm or dementia diagnoses occurred most often within 24 months of a dementia diagnosis or initial self-harm presentation, respectively. Men living with dementia, and people with complex psychiatric profiles, had the greatest risk of self-harm. Men who had self-harmed had the greatest risk of dementia diagnoses. DISCUSSION Men and people with complex psychiatric profiles and dementia may particularly benefit from post-diagnosis mental and behavioral support to reduce risk of self-harm.
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Cvejic RC, Watkins TR, Walker AR, Reppermund S, Srasuebkul P, Draper B, Withall A, Winkler D, Honan I, Mackechnie D, Trollor J. Factors associated with discharge from hospital to residential aged care for younger people with neuropsychiatric disorders: an exploratory case-control study in New South Wales, Australia. BMJ Open 2022; 12:e065982. [PMID: 36456001 PMCID: PMC9716979 DOI: 10.1136/bmjopen-2022-065982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
OBJECTIVES To examine the sociodemographic and diagnostic factors associated with a discharge from hospital to residential aged care (RAC) for younger people (aged 15-64 years) with neuropsychiatric disorders. DESIGN An exploratory case-control study using a historic cohort of people with neuropsychiatric disorders. Cases were people transferred to RAC on hospital discharge during the study period. Controls were people not transferred to RAC on discharge during the study period. SETTING Public and private hospital admissions in New South Wales (NSW), Australia. PARTICIPANTS People aged 15-64 years with a neuropsychiatric disorder hospitalised in NSW between July 2002 and June 2015 (n=5 16 469). OUTCOME MEASURES The main outcome was transferred to RAC on discharge from hospital. We calculated ORs for sociodemographic and diagnostic factors to determine factors that may impact discharge to RAC. RESULTS During the period of data capture, 4406 people were discharged from hospitals to RAC. Discharge to RAC was most strongly associated with diagnoses of progressive neurological and cognitive disorders. Acute precipitants of RAC transfer included a broad range of conditions and injuries (eg, Wernicke's encephalopathy, stroke, falls) in the context of issues such as older age, not being partnered (married or de facto), living in areas of lower socioeconomic status, functional issues and the need for palliative care. CONCLUSIONS There are multiple intersecting and interacting pathways culminating in discharge from hospital to RAC among younger people with neuropsychiatric disorders. Improved capacity for interdisciplinary home care and alternative housing and support options for people with high support needs are required.
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Srasuebkul P, Walker AR, Cvejic RC, Trollor JN, Lappin JM, Curtis J, Samaras K, Dean K, Ward PB, Reppermund S. Hospital service utilisation of people previously hospitalised with different subtypes of psychotic disorder: A record linkage study. Aust N Z J Psychiatry 2022; 57:844-853. [PMID: 35920253 DOI: 10.1177/00048674221115642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Little research has examined the physical and mental comorbidities, and health service use patterns, of people diagnosed with psychotic disorder subtypes other than schizophrenia spectrum disorders. This study aims to examine the physical and mental comorbidities, and subsequent hospital service use patterns, of individuals previously hospitalised with various psychotic disorder subtypes using linked health service data. METHODS We included individuals hospitalised with a psychotic disorder in New South Wales, Australia, between 1 July 2002 and 31 December 2014 (N = 63,110). We examined the demographic profile of the cohort and rates of subsequent acute hospital care and ambulatory mental health service use. We compared the rates of subsequent hospital admissions, emergency department presentations and ambulatory mental health treatment days of people hospitalised with different psychotic disorder subtypes to people hospitalised with schizophrenia spectrum disorders using Poisson regression. RESULTS People most recently hospitalised with mood/affective disorders and psychotic symptoms had a higher rate of subsequent hospital admissions than those most recently hospitalised with schizophrenia spectrum and delusional disorders (adjusted incident rate ratio = 1.06; 95% confidence interval = [1.02, 1.10]), while people most recently hospitalised with drug-induced and other organic (adjusted incident rate ratio = 1.19; 95% confidence interval = [1.12, 1.27]) and acute psychotic disorders (adjusted incident rate ratio = 1.10; 95% confidence interval = [1.03, 1.18]) had more subsequent emergency department presentations than those most recently hospitalised with schizophrenia spectrum and delusional disorders. All three groups had fewer subsequent mental health ambulatory days than those most recently hospitalised with schizophrenia spectrum and delusional disorders (adjusted incident rate ratios = 0.85-0.91). CONCLUSION The health profiles and subsequent hospital service use patterns of people previously hospitalised with different psychotic disorder subtypes are heterogeneous, and research is needed to develop targeted health policies to meet their specific health needs.
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Cvejic RC, Srasuebkul P, Walker AR, Reppermund S, Lappin JM, Curtis J, Samaras K, Dean K, Ward P, Trollor JN. The health service contact patterns of people with psychotic and non-psychotic forms of severe mental illness in New South Wales, Australia: A record-linkage study. Aust N Z J Psychiatry 2022; 56:675-685. [PMID: 34256621 DOI: 10.1177/00048674211031483] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE To describe and compare the health profiles and health service use of people hospitalised with severe mental illness, with and without psychotic symptoms. METHODS We conducted a historical cohort study using linked administrative datasets, including data on public hospital admissions, emergency department presentations and ambulatory mental health service contacts in New South Wales, Australia. The study cohort comprised 169,306 individuals aged 12 years and over who were hospitalised at least once with a mental health diagnosis between 1 July 2002 and 31 December 2014. Of these, 63,110 had a recorded psychotic illness and 106,196 did not. Outcome measures were rates of hospital, emergency department and mental health ambulatory service utilisation, analysed using Poisson regression. RESULTS People with psychotic illnesses had higher rates of hospital admission (adjusted incidence rate ratio (IRR) 1.26; 95% confidence interval [1.23, 1.30]), emergency department presentation (adjusted IRR 1.17; 95% confidence interval [1.13, 1.20]) and ambulatory mental health treatment days (adjusted IRR 2.90; 95% confidence interval [2.82, 2.98]) than people without psychotic illnesses. The higher rate of hospitalisation among people with psychotic illnesses was driven by mental health admissions; while people with psychosis had over twice the rate of mental health admissions, people with other severe mental illnesses without psychosis (e.g. mood/affective, anxiety and personality disorders) had higher rates of physical health admissions, including for circulatory, musculoskeletal, genitourinary and respiratory disorders. Factors that predicted greater health service utilisation included psychosis, intellectual disability, greater medical comorbidity and previous hospitalisation. CONCLUSION Findings from this study support the need for (a) the development of processes to support the physical health of people with severe mental illness, including those without psychosis; (b) a focus in mental health policy and service provision on people with complex support needs, and (c) improved implementation and testing of integrated models of care to improve health outcomes for all people experiencing severe mental illness.
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Walker AR, Trollor JN, Reppermund S, Srasuebkul P. Reviewing causes of death of individuals with intellectual disability in New South Wales, Australia: a record-linkage study. JOURNAL OF INTELLECTUAL DISABILITY RESEARCH : JIDR 2021; 65:998-1009. [PMID: 34609033 DOI: 10.1111/jir.12888] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Revised: 09/08/2021] [Accepted: 09/08/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND People with intellectual disability (ID) have a much higher mortality rate than the general population. To reduce the rate of mortality of people with ID, it is critical that causes of death are properly understood, recorded and reported. Formal reviews of causes of death are used in some countries to ensure that causes of death are accurate. To date, the impact of these formal reviews on understanding causes of death of people with ID has not been quantified. METHODS The study aimed to quantify the impact of formal reviews of deaths on the understanding of causes of death of people with ID who died while living in residential care. Individuals (851) with ID who died in residential care in New South Wales (NSW), Australia, between 1 December 2002 and 31 December 2013, who had a cause of death recorded in both the NSW Cause of Death Unit Record File (COD-URF; cause of death recorded at time of death) and NSW Ombudsman dataset (cause of death recorded after in-depth review) were included in the study. We assessed agreement in coding for cause of death by comparing the International Classification of Diseases 10th Revision (ICD-10) codings at three levels of diagnostic specificity, for both underlying and additional causes of death. We conducted our analysis through both descriptive comparison and through two boosted regression trees. RESULTS Approximately half of the underlying causes of death were different after review by the NSW Ombudsman compared with the COD-URF. Certain causes of death (determined by ICD-10 chapter) were less likely to predict matches between the dataset than others, with individuals with mental, behavioural and neurodevelopmental disorders recorded in the COD-URF least likely to have a matching cause of death in NSW Ombudsman dataset. For deaths where there was no agreement at any level between the datasets, a high level of unknown causes of death was recorded. CONCLUSIONS Formal review of deaths of people with ID in residential care is important to determining true causes of death and therefore developing appropriate health policy for people with ID.
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Walker AR, Navarro DJ, Newell BR, Beesley T. Protection from uncertainty in the exploration/exploitation trade-off. J Exp Psychol Learn Mem Cogn 2021; 48:547-568. [PMID: 34110879 DOI: 10.1037/xlm0000883] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The exploration/exploitation trade-off (EE trade-off) describes how, when faced with several competing alternatives, decision-makers must often choose between a known good alternative (exploitation) and one or more unknown but potentially more rewarding alternatives (exploration). Prevailing theory on how humans perform the EE trade-off states that uncertainty is a major motivator for exploration: the more uncertain the environment, the more exploration that will occur. The current article examines whether exploratory behavior in both choice and attention may be impacted differently depending on whether uncertainty is onset suddenly (unexpected uncertainty), or more slowly (expected uncertainty). It is shown that when uncertainty was expected, participants tended to explore less with their choices, but not their attention, than when it was unexpected. Crucially, the impact of this "protection from uncertainty" on exploration only occurred when participants had an opportunity to learn the structure of the task before experiencing uncertainty. This suggests that the interaction between uncertainty and exploration is more nuanced than simply more uncertainty leading to more exploration, and that attention and choice behavior may index separate aspects of the EE trade-off. (PsycInfo Database Record (c) 2021 APA, all rights reserved).
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Newman VE, Yee HF, Walker AR, Toumbelekis M, Most SB. Out of fright, out of mind: impaired memory for information negated during looming threat. Cogn Res Princ Implic 2021; 6:36. [PMID: 33961162 PMCID: PMC8102851 DOI: 10.1186/s41235-021-00302-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 04/28/2021] [Indexed: 11/16/2022] Open
Abstract
People often need to update representations of information upon discovering them to be incorrect, a process that can be interrupted by competing cognitive demands. Because anxiety and stress can impair cognitive performance, we tested whether looming threat can similarly interfere with the process of updating representations of a statement's truthfulness. On each trial, participants saw a face paired with a personality descriptor. Each pairing was followed by a signal indicating whether the pairing was "true", or "false" (a negation of the truth of the statement), and this signal could be followed by a warning of imminent electric shock (i.e., the looming threat). As predicted, threat of shock left memory for "true" pairings intact, while impairing people's ability to label negated pairings as untrue. Contrary to our predictions, the pattern of errors for pairings that were negated under threat suggested that these mistakes were at least partly attributable to participants forgetting that they saw the negated information at all (rather than being driven by miscategorization of the pairings as true). Consistent with this, linear ballistic accumulator modelling suggested that this impaired recognition stemmed from weaker memory traces rather than decisional processes. We suggest that arousal due to looming threat may interfere with executive processes important for resolving competition between mutually suppressive tags of whether representations in memory are "true" or "false".
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Nadler EO, Drlica-Wagner A, Bechtol K, Mau S, Wechsler RH, Gluscevic V, Boddy K, Pace AB, Li TS, McNanna M, Riley AH, García-Bellido J, Mao YY, Green G, Burke DL, Peter A, Jain B, Abbott TMC, Aguena M, Allam S, Annis J, Avila S, Brooks D, Carrasco Kind M, Carretero J, Costanzi M, da Costa LN, De Vicente J, Desai S, Diehl HT, Doel P, Everett S, Evrard AE, Flaugher B, Frieman J, Gerdes DW, Gruen D, Gruendl RA, Gschwend J, Gutierrez G, Hinton SR, Honscheid K, Huterer D, James DJ, Krause E, Kuehn K, Kuropatkin N, Lahav O, Maia MAG, Marshall JL, Menanteau F, Miquel R, Palmese A, Paz-Chinchón F, Plazas AA, Romer AK, Sanchez E, Scarpine V, Serrano S, Sevilla-Noarbe I, Smith M, Soares-Santos M, Suchyta E, Swanson MEC, Tarle G, Tucker DL, Walker AR, Wester W. Constraints on Dark Matter Properties from Observations of Milky Way Satellite Galaxies. PHYSICAL REVIEW LETTERS 2021; 126:091101. [PMID: 33750144 DOI: 10.1103/physrevlett.126.091101] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 12/12/2020] [Accepted: 01/27/2021] [Indexed: 06/12/2023]
Abstract
We perform a comprehensive study of Milky Way (MW) satellite galaxies to constrain the fundamental properties of dark matter (DM). This analysis fully incorporates inhomogeneities in the spatial distribution and detectability of MW satellites and marginalizes over uncertainties in the mapping between galaxies and DM halos, the properties of the MW system, and the disruption of subhalos by the MW disk. Our results are consistent with the cold, collisionless DM paradigm and yield the strongest cosmological constraints to date on particle models of warm, interacting, and fuzzy dark matter. At 95% confidence, we report limits on (i) the mass of thermal relic warm DM, m_{WDM}>6.5 keV (free-streaming length, λ_{fs}≲10h^{-1} kpc), (ii) the velocity-independent DM-proton scattering cross section, σ_{0}<8.8×10^{-29} cm^{2} for a 100 MeV DM particle mass [DM-proton coupling, c_{p}≲(0.3 GeV)^{-2}], and (iii) the mass of fuzzy DM, m_{ϕ}>2.9×10^{-21} eV (de Broglie wavelength, λ_{dB}≲0.5 kpc). These constraints are complementary to other observational and laboratory constraints on DM properties.
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Abbott TMC, Alarcon A, Allam S, Andersen P, Andrade-Oliveira F, Annis J, Asorey J, Avila S, Bacon D, Banik N, Bassett BA, Baxter E, Bechtol K, Becker MR, Bernstein GM, Bertin E, Blazek J, Bridle SL, Brooks D, Brout D, Burke DL, Calcino J, Camacho H, Campos A, Carnero Rosell A, Carollo D, Carrasco Kind M, Carretero J, Castander FJ, Cawthon R, Challis P, Chan KC, Chang C, Childress M, Crocce M, Cunha CE, D'Andrea CB, da Costa LN, Davis C, Davis TM, De Vicente J, DePoy DL, DeRose J, Desai S, Diehl HT, Dietrich JP, Dodelson S, Doel P, Drlica-Wagner A, Eifler TF, Elvin-Poole J, Estrada J, Evrard AE, Fernandez E, Flaugher B, Foley RJ, Fosalba P, Frieman J, Galbany L, García-Bellido J, Gatti M, Gaztanaga E, Gerdes DW, Giannantonio T, Glazebrook K, Goldstein DA, Gruen D, Gruendl RA, Gschwend J, Gutierrez G, Hartley WG, Hinton SR, Hollowood DL, Honscheid K, Hoormann JK, Hoyle B, Huterer D, Jain B, James DJ, Jarvis M, Jeltema T, Kasai E, Kent S, Kessler R, Kim AG, Kokron N, Krause E, Kron R, Kuehn K, Kuropatkin N, Lahav O, Lasker J, Lemos P, Lewis GF, Li TS, Lidman C, Lima M, Lin H, Macaulay E, MacCrann N, Maia MAG, March M, Marriner J, Marshall JL, Martini P, McMahon RG, Melchior P, Menanteau F, Miquel R, Mohr JJ, Morganson E, Muir J, Möller A, Neilsen E, Nichol RC, Nord B, Ogando RLC, Palmese A, Pan YC, Peiris HV, Percival WJ, Plazas AA, Porredon A, Prat J, Romer AK, Roodman A, Rosenfeld R, Ross AJ, Rykoff ES, Samuroff S, Sánchez C, Sanchez E, Scarpine V, Schindler R, Schubnell M, Scolnic D, Secco LF, Serrano S, Sevilla-Noarbe I, Sharp R, Sheldon E, Smith M, Soares-Santos M, Sobreira F, Sommer NE, Swann E, Swanson MEC, Tarle G, Thomas D, Thomas RC, Troxel MA, Tucker BE, Uddin SA, Vielzeuf P, Walker AR, Wang M, Weaverdyck N, Wechsler RH, Weller J, Yanny B, Zhang B, Zhang Y, Zuntz J. Cosmological Constraints from Multiple Probes in the Dark Energy Survey. PHYSICAL REVIEW LETTERS 2019; 122:171301. [PMID: 31107093 DOI: 10.1103/physrevlett.122.171301] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 02/19/2019] [Indexed: 06/09/2023]
Abstract
The combination of multiple observational probes has long been advocated as a powerful technique to constrain cosmological parameters, in particular dark energy. The Dark Energy Survey has measured 207 spectroscopically confirmed type Ia supernova light curves, the baryon acoustic oscillation feature, weak gravitational lensing, and galaxy clustering. Here we present combined results from these probes, deriving constraints on the equation of state, w, of dark energy and its energy density in the Universe. Independently of other experiments, such as those that measure the cosmic microwave background, the probes from this single photometric survey rule out a Universe with no dark energy, finding w=-0.80_{-0.11}^{+0.09}. The geometry is shown to be consistent with a spatially flat Universe, and we obtain a constraint on the baryon density of Ω_{b}=0.069_{-0.012}^{+0.009} that is independent of early Universe measurements. These results demonstrate the potential power of large multiprobe photometric surveys and pave the way for order of magnitude advances in our constraints on properties of dark energy and cosmology over the next decade.
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Chang C, Vikram V, Jain B, Bacon D, Amara A, Becker MR, Bernstein G, Bonnett C, Bridle S, Brout D, Busha M, Frieman J, Gaztanaga E, Hartley W, Jarvis M, Kacprzak T, Kovács A, Lahav O, Lin H, Melchior P, Peiris H, Rozo E, Rykoff E, Sánchez C, Sheldon E, Troxel MA, Wechsler R, Zuntz J, Abbott T, Abdalla FB, Allam S, Annis J, Bauer AH, Benoit-Lévy A, Brooks D, Buckley-Geer E, Burke DL, Capozzi D, Carnero Rosell A, Carrasco Kind M, Castander FJ, Crocce M, D'Andrea CB, Desai S, Diehl HT, Dietrich JP, Doel P, Eifler TF, Evrard AE, Fausti Neto A, Flaugher B, Fosalba P, Gruen D, Gruendl RA, Gutierrez G, Honscheid K, James D, Kent S, Kuehn K, Kuropatkin N, Maia MAG, March M, Martini P, Merritt KW, Miller CJ, Miquel R, Neilsen E, Nichol RC, Ogando R, Plazas AA, Romer AK, Roodman A, Sako M, Sanchez E, Sevilla I, Smith RC, Soares-Santos M, Sobreira F, Suchyta E, Tarle G, Thaler J, Thomas D, Tucker D, Walker AR. Wide-Field Lensing Mass Maps from Dark Energy Survey Science Verification Data. PHYSICAL REVIEW LETTERS 2015; 115:051301. [PMID: 26274409 DOI: 10.1103/physrevlett.115.051301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Indexed: 06/04/2023]
Abstract
We present a mass map reconstructed from weak gravitational lensing shear measurements over 139 deg2 from the Dark Energy Survey science verification data. The mass map probes both luminous and dark matter, thus providing a tool for studying cosmology. We find good agreement between the mass map and the distribution of massive galaxy clusters identified using a red-sequence cluster finder. Potential candidates for superclusters and voids are identified using these maps. We measure the cross-correlation between the mass map and a magnitude-limited foreground galaxy sample and find a detection at the 6.8σ level with 20 arc min smoothing. These measurements are consistent with simulated galaxy catalogs based on N-body simulations from a cold dark matter model with a cosmological constant. This suggests low systematics uncertainties in the map. We summarize our key findings in this Letter; the detailed methodology and tests for systematics are presented in a companion paper.
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Walker AR. Perplexities and controversies on diet and dental caries. World Rev Nutr Diet 2015; 54:174-200. [PMID: 3327241 DOI: 10.1159/000415305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Walker AR. Bowel characteristics in South African populations with differing pronenesses to non-infective bowel diseases. FRONTIERS OF GASTROINTESTINAL RESEARCH 2015; 4:122-33. [PMID: 428884 DOI: 10.1159/000402293] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Walker AR. Ticks and associated diseases: a retrospective review. MEDICAL AND VETERINARY ENTOMOLOGY 2014; 28 Suppl 1:1-5. [PMID: 24506275 DOI: 10.1111/mve.12031] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Revised: 04/10/2013] [Accepted: 04/18/2013] [Indexed: 06/03/2023]
Abstract
This is a retrospective review of contributions to the understanding of ticks and associated diseases published in Medical and Veterinary Entomology since its first issue. It highlights the large and significant changes in the style and conduct of this field over the last 25 years. The selected papers refer to disease-related categories of host immunity to ticks, population dynamics, pathogen transmission and tick control.
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Steyn NP, Walker AR. Nutritional status and food security in Sub-Saharan Africa: Predictions for 2020. Asia Pac J Clin Nutr 2014; 9:1-6. [PMID: 24394308 DOI: 10.1046/j.1440-6047.2000.00138.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The subject of the future regarding nutritional status and food security, and of their ramifications in terms of nutrition-related disorders/diseases in Sub-Saharan African (SSA) populations, is a complex one. As well as social unrest, a country's socioeconomic situation may affect food availability and, crucially, influence the generally low proportions of the Gross National Product devoted to health services. Additional determinants include changes in the roles of non-dietary adverse factors (i.e. smoking practice, alcohol consumption, physical inactivity) and of infections (i.e. gastroenteritis, malaria, tuberculosis and, particularly, HIV). As to future health in 2020, major increases in socioeconomic status are very unlikely; in fact, there has been a deterioration in some countries with food shortages affecting nutrition status and food security. However, with some measures of prosperity there are likely to be decreases in family size and falls in the proportions of children born with low birthweights or with protein-energy-malnutrition (PEM), and of children lying under the 5th percentile of growth reference standards. Simultaneously, though. there will be variable rises, especially in urban dwellers, in the occurrence of hypertension, diabetes, cardiovascular disease and certain cancers. Improvements in the health status of both children and adults are likely to be strongly affected by whether HIV infection can be controlled or whether it becomes rampant.
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Katzer F, Ngugi D, Walker AR, McKeever DJ. Genotypic diversity, a survival strategy for the apicomplexan parasite Theileria parva. Vet Parasitol 2009; 167:236-43. [PMID: 19837514 PMCID: PMC2817781 DOI: 10.1016/j.vetpar.2009.09.025] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The tick-borne protozoan parasite Theileria parva causes East Coast fever (ECF), a severe lymphoproliferative disease of cattle that is a major constraint to the improvement of livestock in eastern, central and southern Africa. Studies in cattle experimentally infected with T. parva have shown that the protective cytotoxic T lymphocyte (CTL) response is tightly focused, with individual animals recognizing only one or two dominant antigens, the identity of which varies with MHC class I phenotype. It is well known that cross-protection between T. parva stocks is limited, but precise evaluation of genetic diversity in field populations of the parasite has been hampered by a lack of molecular markers spanning the genome. A recently described panel of satellite markers has provided evidence for substantial genotypic diversity and recombination but does not provide cover for large segments of the genome. To address this deficiency, we undertook to identify additional polymorphic markers covering these regions and we report herein 42 newly identified PCR-RFLP markers distributed across the 4 T. parva chromosomes, as well as 19 new satellite markers for chromosomes 1 and 2. This brings the total number of available polymorphic markers to 141 for the 8.5 Mb genome. We have used these markers to characterise existing parasite stabilates and have also shown that passage of the parasite through naïve cattle and ticks can lead to substantial changes of parasite populations in resulting stabilates. These markers have also been used to show that passage of mixed parasites through an immunised calf results in the removal of the immunising genotype from the parasite population produced by ticks fed on this animal.
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Conn VM, Walker AR, Franco CMM. Endophytic actinobacteria induce defense pathways in Arabidopsis thaliana. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2008; 21:208-18. [PMID: 18184065 DOI: 10.1094/mpmi-21-2-0208] [Citation(s) in RCA: 160] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Endophytic actinobacteria, isolated from healthy wheat tissue, which are capable of suppressing a number wheat fungal pathogens both in vitro and in planta, were investigated for the ability to activate key genes in the systemic acquired resistance (SAR) or the jasmonate/ethylene (JA/ET) pathways in Arabidopsis thaliana. Inoculation of A. thaliana (Col-0) with selected endophytic strains induced a low level of SAR and JA/ET gene expression, measured using quantitative polymerase chain reaction. Upon pathogen challenge, endophyte-treated plants demonstrated a higher abundance of defense gene expression compared with the non-endophyte-treated controls. Resistance to the bacterial pathogen Erwinia carotovora subsp. carotovora required the JA/ET pathway. On the other hand, resistance to the fungal pathogen Fusarium oxysporum involved primarily the SAR pathway. The endophytic actinobacteria appear to be able to "prime" both the SAR and JA/ET pathways, upregulating genes in either pathway depending on the infecting pathogen. Culture filtrates of the endophytic actinobacteria were investigated for the ability to also activate defense pathways. The culture filtrate of Micromonospora sp. strain EN43 grown in a minimal medium resulted in the induction of the SAR pathway; however, when grown in a complex medium, the JA/ET pathway was activated. Further analysis using Streptomyces sp. strain EN27 and defense-compromised mutants of A. thaliana indicated that resistance to E. carotovora subsp. carotovora occurred via an NPR1-independent pathway and required salicylic acid whereas the JA/ET signaling molecules were not essential. In contrast, resistance to F. oxysporum mediated by Streptomyces sp. strain EN27 occurred via an NPR1-dependent pathway but also required salicylic acid and was JA/ET independent.
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Walker AR, Rothberg PG, Liesveld JL. A case of JAK2 positive essential thrombocythemia 16.5 years after autologous marrow transplantation for AML. Bone Marrow Transplant 2007; 39:725-6. [PMID: 17401398 DOI: 10.1038/sj.bmt.1705647] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Walker AR, Katzer F, Ngugi D, McKeever D. Cloned Theileria parva produces lesser infections in ticks compared to uncloned T. parva despite similar infections in cattle. ACTA ACUST UNITED AC 2006; 73:157-62. [PMID: 16958269 PMCID: PMC2628563 DOI: 10.4102/ojvr.v73i2.163] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
Abstract
Experimental transmissions of cloned Theileria parva in cattle with Rhipicephalus appendiculatus ticks were compared to transmissions with uncloned T. parva during studies on the potential for genetic recombination during syngamy of Theileria to produce antigenic diversity for evasion of bovine immunity. Prevalence and abundance of T. parva infection in adult ticks, which resulted from the feeding of nymphs on the calves, were significantly higher in the uncloned compared to the cloned T. parva. Development of sporoblasts of T. parva in the ticks to produce infective sporozoites was similar. There was no statistically significant difference in the clinical course of infection in cattle between cloned and uncloned T. parva. It was concluded that cloned T. parva has characteristics that reduce its viability during the tick stages of its life cycle.
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Walker AR, Fox FW, Irving JT. Studies in human mineral metabolism: 1. The effect of bread rich in phytate phosphorus on the metabolism of certain mineral salts with special reference to calcium. Biochem J 2006; 42:452-62. [PMID: 16748311 PMCID: PMC1258738 DOI: 10.1042/bj0420452] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Prekker ME, Nath DS, Walker AR, Johnson AC, Hertz MI, Herrington CS, Radosevich DM, Dahlberg PS. Validation of the Proposed International Society for Heart and Lung Transplantation Grading System for Primary Graft Dysfunction After Lung Transplantation. J Heart Lung Transplant 2006; 25:371-8. [PMID: 16563963 DOI: 10.1016/j.healun.2005.11.436] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2005] [Revised: 08/09/2005] [Accepted: 11/02/2005] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND A scoring system was recently proposed to grade the severity of primary graft dysfunction (PGD), a frequent early complication of lung transplantation. The purposes of this study are to: (1) validate the PGD grading system with respect to patient outcomes; and (2) compare the performance of criteria employing the arterial oxygenation to fraction of inspired oxygen (P/F) ratio to an alternative grading system employing the oxygenation index (OI). METHODS We retrospectively reviewed the medical records of 402 patients having undergone lung transplantation at our institution from 1992 through 2004. The ISHLT PGD grading system was modified and grades were assigned up to 48 hours post-transplantation as follows: Grade 1 PGD, P/F > 300; Grade 2, P/F 200 to 300; and Grade 3, P/F < 200. A worst score T(0-48) was also assigned, which reflects the highest grade recorded between T0 and T48. RESULTS The prevalence of severe PGD (P/F Grade 3) declined after transplant, from 25% at T0 to 15% at T48. Grouping patients by P/F grade at T48 demonstrated the clearest differentiation of 90-day death rates (Grade 1, 7%; Grade 2, 12%; Grade 3, 33%) (p = 0.0001). T48 OI grade also differentiates 90-day death rates. There was no difference in longer-term survival between patients with PGD Grades 1 and 2. OI grade at T0 qualitatively improved differential mortality between Grades 1 and 2; however, the differences did not reach statistical significance. Patients with a worst score T(0-48) of Grade 3 PGD did have significantly decreased long-term survival, as well as longer ICU and hospital stay, when compared with Grades 1 and 2 PGD. Significant risk factors for short- and long-term mortality in our multivariate model were P/F Grade 3 [worst score T(0-48) as well as T0 grade], single-lung transplant, use of cardiopulmonary bypass and high pre-operative mean pulmonary artery pressure. CONCLUSIONS There is an increased risk of short- and long-term mortality and length of hospital stay associated with severe (Grade 3) PGD. The proposed ISHLT grading system can rapidly identify patients with poor outcomes who may benefit from early, aggressive treatment. Refinement of the scoring system may further improve patient risk stratification.
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