Can different Catphan phantoms be used in a multi-centre audit of radiotherapy CT image quality?

PURPOSE: To determine the variation between Catphan image quality CT phantoms, specifically for use in a future multi-centre image quality audit. METHOD: 14 Catphan phantoms (models 503, 504 and 604) were scanned on a Canon Aquilion Prime CT scanner using a single scan protocol. Measurements were made of noise in the uniformity section, visibility of low contrast targets and contrast, x-ray attenuation and CT number for 5 materials in the sensitometry section. Scans were also acquired using one phantom and varying reconstruction field of view, image slice thickness, effective tube-current-time product and iterative reconstruction settings to determine how the degree of inter-phantom variability compared with the magnitude of changes from scan parameter alteration. RESULTS: Across all phantoms the mean CT value in the uniformity section was 7.0 (SD 0.9) range: 4.9-8.1 HU. For the different materials the CT numbers were air: -1004 ± 5, Polymethylpentene: -190 ± 2, Polystyrene: -42 ± 2, Delrin: 321 ± 5 and Teflon: 898 ± 8 HU. Consistency of low contrast targets through visual scoring was good. Measured contrast was lower (p < 0.001) with more variability for 504 versus 604 models. All phantoms produced identical tube current settings with x-ray tube current modulation, indicating no x-ray attenuation differences. The degree of change in image quality metrics between phantoms was small compared with results when scan parameters were varied. CONCLUSION: Catphan phantoms model 604 showed minimal differences and will be used for multi-centre inter-comparison work, with the consistency between phantoms appropriate for measuring possible variations in image quality

Selective probing of magnetic order on Tb and Ir sites in stuffed Tb_2+xIr_2-xO_7-y using resonant X-ray scattering

We study the magnetic structure of the ``stuffed" (Tb-rich) pyrochlore iridate Tb$_{2+x}$Ir$_{2-x}$O$_{7-y}$, using resonant elastic x-ray scattering (REXS). In order to disentangle contributions from Tb and Ir magnetic sublattices, experiments were performed at the Ir $L_3$ and Tb $M_5$ edges, which provide selective sensitivity to Ir $5d$ and Tb $4f$ magnetic moments, respectively. At the Ir $L_3$ edge, we found the onset of long-range ${\bf k}={\bf 0}$ magnetic order below $T_{N}^\text{Ir}\sim$\,71\,K, consistent with the expected signal of all-in all-out (AIAO) magnetic order. Using a single-ion model to calculate REXS cross-sections, we estimate an ordered magnetic moment of $\mu_{5d}^{\text{Ir}} \approx 0.34(3)\,\mu_B$ at 5\,K. At the Tb $M_5$ edge, long-range ${\bf k}={\bf 0}$ magnetic order appeared below $\sim40\,$K, also consistent with an AIAO magnetic structure on the Tb site. Additional insight into the magnetism of the Tb sublattice is gleaned from measurements at the $M_5$ edge in applied magnetic fields up to 6\,T, which is found to completely suppress the Tb AIAO magnetic order. In zero applied field, the observed gradual onset of the Tb sublattice magnetisation with temperature suggests that it is induced by the magnetic order on the Ir site. The persistence of AIAO magnetic order, despite the greatly reduced ordering temperature and moment size compared to stoichiometric Tb$_{2}$Ir$_{2}$O$_{7}$, for which $T_{N}^{\text{Ir}} =130\,$K and $\mu_{5d}^{\text{Ir}}=0.56\,\mu_B$, indicates that stuffing could be a viable means of tuning the strength of electronic correlations, thereby potentially offering a new strategy to achieve topologically non-trivial band crossings in pyrochlore iridates

A cross-sectional study examining predictors of visit frequency to local green space and the impact this has on physical activity levels

Background Lack of physical activity (PA) is a growing public health concern. There is a growing body of literature that suggests a positive relationship may exist between the amount of local green space near one?s home and PA levels. For instance, park proximity has been shown to predict PA levels amongst certain populations. However, there is little evidence for the role of relatedness towards nature and perceptions of local green space on this relationship. The aim of this study was to examine, in a National UK sample, whether subjective indices associated with local green space were better predictors of visit frequency to local green space and PA levels compared to objectively measured quantity of local green space. Methods A cross-sectional survey was designed. From a random sample, 2079 working age adults responded to an online survey in September 2011. Demographics, self-reported PA, objective measures of the local environment (including local green space, road coverage, and environmental deprivation), were assessed in conjunction with perceptions of local green space and nature relatedness. Quantity of local green space was assessed by cross-referencing respondents? home postcodes with general land use databases. Regression models were conducted to assess which of our independent variables best predicted visit frequency to local green space and/or meeting PA guidelines. In addition, an ordinal regression was run to examine the relationship between visit frequency to local green space and the likelihood of meeting national PA guidelines. Results Nature relatedness was the strongest predictor for both visit frequency to local green space and meeting PA guidelines. Results show that perceived quality is a better predictor of visit frequency to local green space than objective quantity of local green space. The odds of achieving the recommended amount of PA was over four times greater for people who visited local green space once per week compared to never going (OR 4.151; 95 % CI, 2.40 to 7.17). Conclusions These results suggest that perceptions of local green space and nature relatedness play an important role in the relationship between local green space and PA. Considering the known health benefits of PA, our results are potentially important for public health interventions, policy making and environmental planning

Risk factors for suicide in Bali: a psychological autopsy study

<p>Abstract</p> <p>Background</p> <p>The suicide rate in Bali has significantly increased in recent years. However, to date, there have been no case-control studies investigating risk factors for suicide.</p> <p>Methods</p> <p>A psychological autopsy study was conducted comparing 60 suicide cases and 120 living controls matched in age, sex, and area of residence.</p> <p>Results</p> <p>Multiple logistic regression analysis identified the following risk factors for suicide: at least one diagnosis of axis-I mental disorder (OR: 14.84 CI: 6.12 - 35.94); low level of religious involvement (OR: 7.24 CI: 2.28 - 22.95); and severe interpersonal problems (OR: 3.86 CI: 1.36 - 11.01). Forty-eight (80.0%) of the suicide cases were diagnosed with mental disorders; however, only 16.7% visited a primary care health professional and none received psychiatric treatment during the 1 month prior to death.</p> <p>Conclusion</p> <p>Clinical, religious, and psychosocial factors were associated with suicide. These results highlight the significance of early recognition and treatment of mental disorders, religious activities, and interpersonal problem-solving strategies for suicide prevention in Bali.</p

Conceptual Frameworks and Methods for Advancing Invasion Ecology

Invasion ecology has much advanced since its early beginnings. Nevertheless, explanation, prediction, and management of biological invasions remain difficult. We argue that progress in invasion research can be accelerated by, first, pointing out difficulties this field is currently facing and, second, looking for measures to overcome them. We see basic and applied research in invasion ecology confronted with difficulties arising from (A) societal issues, e.g., disparate perceptions of invasive species; (B) the peculiarity of the invasion process, e.g., its complexity and context dependency; and (C) the scientific methodology, e.g., imprecise hypotheses. To overcome these difficulties, we propose three key measures: (1) a checklist for definitions to encourage explicit definitions; (2) implementation of a hierarchy of hypotheses (HoH), where general hypotheses branch into specific and precisely testable hypotheses; and (3) platforms for improved communication. These measures may significantly increase conceptual clarity and enhance communication, thus advancing invasion ecology

Transcriptomic analysis of the temporal host response to skin infestation with the ectoparasitic mite Psoroptes ovis

<p>Abstract</p> <p>Background</p> <p>Infestation of ovine skin with the ectoparasitic mite <it>Psoroptes ovis </it>results in a rapid cutaneous immune response, leading to the crusted skin lesions characteristic of sheep scab. Little is known regarding the mechanisms by which such a profound inflammatory response is instigated and to identify novel vaccine and drug targets a better understanding of the host-parasite relationship is essential. The main objective of this study was to perform a combined network and pathway analysis of the <it>in vivo </it>skin response to infestation with <it>P. ovis </it>to gain a clearer understanding of the mechanisms and signalling pathways involved.</p> <p>Results</p> <p>Infestation with <it>P. </it>ovis resulted in differential expression of 1,552 genes over a 24 hour time course. Clustering by peak gene expression enabled classification of genes into temporally related groupings. Network and pathway analysis of clusters identified key signalling pathways involved in the host response to infestation. The analysis implicated a number of genes with roles in allergy and inflammation, including pro-inflammatory cytokines (<it>IL1A, IL1B, IL6, IL8 </it>and <it>TNF</it>) and factors involved in immune cell activation and recruitment (<it>SELE, SELL, SELP, ICAM1, CSF2, CSF3, CCL2 </it>and <it>CXCL2</it>). The analysis also highlighted the influence of the transcription factors NF-kB and AP-1 in the early pro-inflammatory response, and demonstrated a bias towards a Th2 type immune response.</p> <p>Conclusions</p> <p>This study has provided novel insights into the signalling mechanisms leading to the development of a pro-inflammatory response in sheep scab, whilst providing crucial information regarding the nature of mite factors that may trigger this response. It has enabled the elucidation of the temporal patterns by which the immune system is regulated following exposure to <it>P. ovis</it>, providing novel insights into the mechanisms underlying lesion development. This study has improved our existing knowledge of the host response to <it>P. ovis</it>, including the identification of key parallels between sheep scab and other inflammatory skin disorders and the identification of potential targets for disease control.</p

2D versus 3D human induced pluripotent stem cell-derived cultures for neurodegenerative disease modelling

Neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD) and amyotrophic lateral sclerosis (ALS), affect millions of people every year and so far, there are no therapeutic cures available. Even though animal and histological models have been of great aid in understanding disease mechanisms and identifying possible therapeutic strategies, in order to find disease-modifying solutions there is still a critical need for systems that can provide more predictive and physiologically relevant results. One possible avenue is the development of patient-derived models, e.g. by reprogramming patient somatic cells into human induced pluripotent stem cells (hiPSCs), which can then be differentiated into any cell type for modelling. These systems contain key genetic information from the donors, and therefore have enormous potential as tools in the investigation of pathological mechanisms underlying disease phenotype, and progression, as well as in drug testing platforms. hiPSCs have been widely cultured in 2D systems, but in order to mimic human brain complexity, 3D models have been proposed as a more advanced alternative. This review will focus on the use of patient-derived hiPSCs to model AD, PD, HD and ALS. In brief, we will cover the available stem cells, types of 2D and 3D culture systems, existing models for neurodegenerative diseases, obstacles to model these diseases in vitro, and current perspectives in the field

The self-organizing fractal theory as a universal discovery method: the phenomenon of life

A universal discovery method potentially applicable to all disciplines studying organizational phenomena has been developed. This method takes advantage of a new form of global symmetry, namely, scale-invariance of self-organizational dynamics of energy/matter at all levels of organizational hierarchy, from elementary particles through cells and organisms to the Universe as a whole. The method is based on an alternative conceptualization of physical reality postulating that the energy/matter comprising the Universe is far from equilibrium, that it exists as a flow, and that it develops via self-organization in accordance with the empirical laws of nonequilibrium thermodynamics. It is postulated that the energy/matter flowing through and comprising the Universe evolves as a multiscale, self-similar structure-process, i.e., as a self-organizing fractal. This means that certain organizational structures and processes are scale-invariant and are reproduced at all levels of the organizational hierarchy. Being a form of symmetry, scale-invariance naturally lends itself to a new discovery method that allows for the deduction of missing information by comparing scale-invariant organizational patterns across different levels of the organizational hierarchy