Learning transition times in event sequences: the Event-Based Hidden Markov Model of disease progression

Progressive diseases worsen over time and are characterised by monotonic change in features that track disease progression. Here we connect ideas from two formerly separate methodologies – event-based and hidden Markov modelling – to derive a new generative model of disease progression. Our model can uniquely infer the most likely group-level sequence and timing of events (natural history) from limited datasets. Moreover, it can infer and predict individual-level trajectories (prognosis) even when data are missing, giving it high clinical utility. Here we derive the model and provide an inference scheme based on the expectation maximisation algorithm. We use clinical, imaging and biofluid data from the Alzheimer’s Disease Neuroimaging Initiative to demonstrate the validity and utility of our model. First, we train our model to uncover a new grouplevel sequence of feature changes in Alzheimer’s disease over a period of ∼17.3 years. Next, we demonstrate that our model provides improved utility over a continuous time hidden Markov model by area under the receiver operator characteristic curve ∼0.23. Finally, we demonstrate that our model maintains predictive accuracy with up to 50% missing data. These results support the clinical validity of our model and its broader utility in resourcelimited medical applications

Factors affecting the Gender- based Consumer purchase intention towards Ethical Fashion (A case study on undergraduates of the University of Sri Jayewardenepura)

The study examines the factors affecting the gender-based consumer purchase intention towards ethical fashion in Sri Lanka. Primary data was gathered using self-administrated questionnaire through online platform and physically. Sample of the study was selected using stratified and simple random sampling techniques through undergraduates from three selected faculties of the University of Sri Jayewardenepura. Sample size of the study was 371 respondents including 228 female and 143 male undergraduates. Both descriptive analysis and Structural Equation Modelling (SEM) method were applied for the quantitative data. Findings of the study revealed that both the female and male consumers have an identical level of awareness regarding the ethical fashion market and related scopes. The respondents of the study have a positive impression on ethical fashion concept, and they believe that the concept itself is necessary for the betterment of the society and environment. Attitudes and beliefs regarding ethical fashion and subjective norms were identified as the major factors which affect the purchase intention towards ethical fashion among the consumers. Furthermore, it was found that gender doesn’t have any moderate effect in determining the consumers’ purchase intention towards ethical fashion in the young adult consumers in Sri Lanka. Findings of the study suggested that the fashion industry should implement new methods to motivate the purchasing intention of young customers. Also, such methods should promote the core values of ethical fashion concept as most of the consumers are not aware about those and for the expansion of the ethical fashion industry.  DOI: http://doi.org/10.31357/fhss/vjhss.v08i02.1

Who cooks from scratch and how do they prepare food

Purpose – There is increasing interest in the domestic preparation of food and with the postulated health benefits of “cooking from scratch”. The purpose of this paper is to examine the demographic and food preparation associations of this term in order to examine its operational value. Design/methodology/approach – A national online survey was conducted during 2012 in Australia among 1,023 domestic food providers, half of whom were men. Questions were asked about cooking from scratch, demographic characteristics, food preparation practices and interest in learning about cooking. Findings – Three quarters of the sample reported they often or always “cooked from scratch” (CFS). More women than men always CFS; fewer 18-29 year olds did so often or always but more of the over 50s always did so; fewer single people CFS than cohabiting people. No statistically significant ethnic, educational background or household income differences were found. High levels of cooking from scratch were associated with interest in learning more about cooking, greater use of most cooking techniques (except microwaves), meat and legume preparation techniques, and the use of broader ranges of herbs, spice, liquids/ sauces, other ingredients and cooking utensils. Research limitations/implications – In future work a numerical description of the frequency of cooking from scratch should be considered along with a wider range of response options. The data were derived from an online panel from which men were oversampled. Caution is required in comparisons between men and women respondents. The cross-sectional nature of the sample prevents any causal attributions from being drawn from the observed relationships. Further replication of the findings, especially the lack of association with educational background should be conducted. Originality/value – This is the first study to examine the associations of demographic characteristics and cooking practices with cooking from scratch. The findings suggest that cooking from scratch is common among Australian family food providers and signifies interest in learning about cooking and involvement in a wide range of cooking techniques

Towards a Steady State Economy in Sri Lanka

In general, it is desired that Sri Lankan economy shows growth. A growing economy brings waste production which leads environmental pollutions such as air pollution water pollution etc. At present, increasing population in Sri Lanka requires more natural resources to meet the market demand. The ultimate result is an imbalance in the biological cycles, and an irreversible change in both economic process and environment.An irreversible economic process increases entropy. Ultimately, the entropy will reach its maximum value. Then everything will become standstill since there would not exist more energy to continue the economic process. As a solution, the concept of a steady state economy is structured.Sri Lankan economy was assessed within steady state economics to evaluate the present economic situation of Sri Lanka. A statistical analysis was carried out on Gross Domestic Product (GDP), population, energy use, CO2 emission through time series analysis and regression analysis,to identify the extent to which Sri Lankan economy has deviated from a steady state economy. Regression analysis indicates a strong relationship between GDP and CO2 emission. Total population size in Sri Lanka is increased from 9.9 million in 1960 to 20.48 million in 2013. CO2 emission per capita is increased from 0.25 metric tons in 1960 to 0.65 metric tons in 2010. CO2 emission is increased from 2259 kiloton in 1960 to 12831 kiloton in 2010.Rapid growth rates, CO2 emissions, population growth rates reveal that Sri Lankan economy is far apart from the concept of steady state.Transition to a steady state economy would require the implementation of new policies to restrict the utilization of nonrenewable resources. On the other hand it is mandatory to have legal regulations encouraging renewable resource use, energy efficiency, and reuse and recycling

Seiches around the Shetland Islands

Sea level records have been obtained from a dozen tide gauges deployed around the Shetland Islands, and the high-frequency components of each record have been analysed to determine how the amplitudes and periods of seiches vary from place to place. We have found that seiches occur almost everywhere, although with different periods at different locations, and sometimes with amplitudes exceeding several decimetres. Spectral analysis shows that two or more modes of seiching are present at some sites. The study attempts to explain, with the help of a numerical model, why seiches with particular periods are observed at each location, and what forcings are responsible for them. In particular, we have revisited an earlier study of seiches on the east coast of Shetland by Cartwright and Young (Proc R Soc Lond A 338:111–128, 1974) and find no evidence to support the theory that they proposed for their generation. In addition, we have investigated how often and why the largest seiche events occur at Lerwick (with trough-to-crest wave heights of about 1 m), taking advantage of its long sea level record. Seiches (and other types of high-frequency sea level variability) are often ignored in studies of sea level changes and their coastal impacts. And yet they can be large enough to contribute significantly to the extreme sea levels that have major impacts on the coast. Therefore, our Shetland research serves as a case study of the need to have a fuller understanding of the climatology of seiches for the whole world coastline

Coverage gaps in empiric antibiotic regimens used to treat serious bacterial infections in neonates and children in Southeast Asia and the Pacific

Background: High levels of antimicrobial resistance (AMR) are propagating deaths due to neonatal and paediatric infections globally. This is of particular concern in Southeast Asia and the Pacific, where healthcare resources are constrained and access to newer agents to treat multidrug-resistant pathogens is limited. Methods: To assess the coverage provided by commonly prescribed empiric antibiotic regimens for children in low- and middle-income countries in Southeast Asia and the Pacific, we built a weighted incidence syndromic combination antibiogram (WISCA), parameterised using data obtained from a systematic review of published literature incorporating WHO-defined SEARO and WPRO regions in Ovid MEDLINE, EMBASE, Global Health and PubMed. Susceptibility data for bacterial pathogens were extracted to provide coverage estimates for pre-specified antibiotics (aminopenicillins, gentamicin, third-generation cephalosporins and carbapenems), reported at the regional level. Findings: 6648 bacterial isolates from 11 countries across 86 papers were included in the Bayesian WISCA model, which weighted bacterial incidence and antimicrobial susceptibility of relevant isolates. Coverage provided by aminopenicillins in neonatal sepsis/meningitis was 26% (80% credible interval: 16–49) whilst gentamicin coverage was 45% (29–62). Third-generation cephalosporin coverage was only 29% (16–49) in neonatal sepsis/meningitis, 51% (38–64) in paediatric sepsis and 65% (51–77) in paediatric meningitis. Carbapenems were estimated to provide the highest coverage: 81% (65–90) in neonatal sepsis/meningitis, 83% (72–90) in paediatric sepsis and 79% (62–91) in paediatric meningitis. Interpretation: These findings reveal alarmingly high rates of resistance to commonly prescribed empirical therapies for neonatal and paediatric sepsis and meningitis in the Asia–Pacific region

Impurity-assisted tunneling in graphene

The electric conductance of a strip of undoped graphene increases in the presence of a disorder potential, which is smooth on atomic scales. The phenomenon is attributed to impurity-assisted resonant tunneling of massless Dirac fermions. Employing the transfer matrix approach we demonstrate the resonant character of the conductivity enhancement in the presence of a single impurity. We also calculate the two-terminal conductivity for the model with one-dimensional fluctuations of disorder potential by a mapping onto a problem of Anderson localization.Comment: 6 pages, 3 figures, final version, typos corrected, references adde

Implementation of a quality improvement programme to support advance care planning in five hospitals across a health region.

OBJECTIVES: Advance care planning (ACP) can help patients with a terminal illness to prepare for the end of their lives. This report describes a regional service improvement initiative to increase the identification of hospital inpatients at this stage in their illnesses and to increase the number of such patients who are offered the opportunity to start the process of ACP. METHODS: Data were collected prospectively over a 7 month period from four acute hospital trusts and a specialist cancer centre in the South-West London region. Each unit identified a specific patient population who were screened for eligibility to engage in the process of ACP. Data concerning the reasons for eligibility, the suitability for discussion and the various reasons why patients did not complete the process, were recorded. RESULTS: Over a 7 month period 1980 patients were screened and 559 (28.2%) were found to be potentially eligible for an ACP discussion. Of these 227/559 (40.6%) were deemed suitable for a discussion by medical staff. The majority of these patients (195/227; 86%) were offered the opportunity to undergo ACP discussions and 144/195 (73.8%) agreed to begin the process of ACP. CONCLUSIONS: This report shows that a targeted approach can result in increased uptake in the number of patients who engage in ACP. However, systematic identification of potentially eligible patients requires a significant investment of clinical time and resources

A data-driven study of Alzheimer's disease related amyloid and tau pathology progression

Amyloid-beta is thought to facilitate the spread of tau throughout the neocortex in Alzheimer's disease, though how this occurs is not well understood. This is because of the spatial discordance between amyloid-beta, which accumulates in the neocortex, and tau, which accumulates in the medial temporal lobe during aging. There is evidence that in some cases amyloid-beta-independent tau spreads beyond the medial temporal lobe where it may interact with neocortical amyloid-beta. This suggests that there may be multiple distinct spatiotemporal subtypes of Alzheimer's-related protein aggregation, with potentially different demographic and genetic risk profiles. We investigated this hypothesis, applying data-driven disease progression subtyping models to post-mortem neuropathology and in vivo PET based measures from two large observational studies: the Alzheimer's Disease Neuroimaging Initiative and the Religious Orders Study and Rush Memory and Aging Project. We consistently identified 'amyloid-first' and 'tau-first' subtypes using cross-sectional information from both studies. In the amyloid-first subtype, extensive neocortical amyloid-beta precedes the spread of tau beyond the medial temporal lobe, while in the tau-first subtype mild tau accumulates in medial temporal and neocortical areas prior to interacting with amyloid-beta. As expected, we found a higher prevalence of the amyloid-first subtype among apolipoprotein E (APOE) ε4 allele carriers while the tau-first subtype was more common among APOE ε4 non-carriers. Within tau-first APOE ε4 carriers, we found an increased rate of amyloid-beta accumulation (via longitudinal amyloid PET), suggesting that this rare group may belong within the Alzheimer's disease continuum. We also found that tau-first APOE ε4 carriers had several fewer years of education than other groups, suggesting a role for modifiable risk factors in facilitating amyloid-beta-independent tau. Tau-first APOE ε4 non-carriers, in contrast, recapitulated many of the features of Primary Age-related Tauopathy. The rate of longitudinal amyloid-beta and tau accumulation (both measured via PET) within this group did not differ from normal aging, supporting the distinction of Primary Age-related Tauopathy from Alzheimer's disease. We also found reduced longitudinal subtype consistency within tau-first APOE ε4 non-carriers, suggesting additional heterogeneity within this group. Our findings support the idea that amyloid-beta and tau may begin as independent processes in spatially disconnected regions, with widespread neocortical tau resulting from the local interaction of amyloid-beta and tau. The site of this interaction may be subtype-dependent: medial temporal lobe in amyloid-first, neocortex in tau-first. These insights into the dynamics of amyloid-beta and tau may inform research and clinical trials that target these pathologies