In analysis of survival outcomes supplemented with both clinical information and high-dimensional gene expression data, use of the traditional Cox proportional hazards model fails to meet some ...emerging needs in biomedical research. First, the number of covariates is generally much larger the sample size. Secondly, predicting an outcome based on individual gene expression is inadequate because multiple biological processes and functional pathways regulate phenotypic expression. Another challenge is that the Cox model assumes that populations are homogenous, implying that all individuals have the same risk of death, which is rarely true due to unmeasured risk factors among populations. In this paper we propose group LASSO with gamma-distributed frailty for variable selection in Cox regression by extending previous scholarship to account for heterogeneity among group structures related to exposure and susceptibility. The consistency property of the proposed method is established. This method is appropriate for addressing a wide variety of research questions from genetics to air pollution. Simulated and real world data analysis shows promising performance by group LASSO compared with other methods, including group SCAD and group MCP. Future research directions include expanding the use of frailty with adaptive group LASSO and sparse group LASSO methods.
Particulate matter (PM) pollution in China has an obvious characteristic of spatial distribution. It is well known that intensive anthropogenic activities, such as fossil fuel combustion and biomass ...burning, have great influence on the spatial distribution of PM pollution. However, the spacescale-dependent relationships between PM concentrations and weather conditions remain unclear. Here, we investigated the characteristics of two types of particulate pollution, including PM2.5 and PM10, and their spatial relationships with meteorological elements in 173 cities throughout China from March 2014 to February 2015. Results: (1) High PM2.5 concentrations were distinctly located southeast of the Hu Line, and high PM10 concentrations were distinctly situated north of the Yangtze River; (2) Spacescale-dependent relationships were found between PM pollution and meteorological elements. The influence of temperature had similar inverted V-shaped characteristics, namely, there was serious PM pollution when temperature was about 15 °C, and there was slight PM pollution when temperature was less or more than 15 °C. Annual precipitation, wind speed, and relative humidity were negatively correlated with PM, while annual atmospheric pressure was positively correlated with PM; (3) The ideal meteorological regions were identified according to the quantified spatial relationships between PM and meteorological elements, which could be defined by a combination of the following conditions: (a) temperature <10 °C or >21 °C; (b) precipitation >1500 mm; (c) atmospheric pressure <900 hPa; (d) wind speed >3 m/s; and (e) relative humidity >65%, where air pollutants can easily be scavenged. The success of this research provides a meteorological explanation to the spatial distribution characteristics of PM pollution in China.
Land use regression (LUR) models are widely used in epidemiological studies to assess exposure to air pollution. However, most of the existing LUR studies focus on estimating annual or monthly ...average concentration of air pollutants, with high spatial but low temporal resolution. In this paper, we combined LUR models with meteorological conditions to estimate daily nitrogen dioxide (NO2) and particulate matter (PM10) concentrations in the urban area of Changsha, China. Seventy-four sites for NO2 and thirty-six sites for PM10 were selected to build LUR models. The LUR models explained 51% and 62% of spatial variability for NO2 and PM10. The most important spatial explanatory variables included major roads, residential land and public facilities land, indicating that the spatial distributions of NO2 and PM10 are closely related to traffic conditions and human activities. Meteorological factors were introduced to model the temporal variability of NO2 and PM10 by using meteorological factors regression (MFR) and back propagation neural network (BPNN) modeling techniques. Important temporal explanatory variables included temperature, wind speed, cloud cover and percentage of haze. Pearson's r values between predicted and measured concentrations were much higher in BPNN models than in MFR models. The results demonstrate that the BPNN models showed a better performance than the MFR models in modeling temporal variation of NO2 and PM10. The approach of modeling spatial and temporal variation of air pollutants using LUR models coupled with meteorological conditions has potential usefulness for exposure assessment, especially for medium or short term exposure, in health studies.
•Daily NO2 and PM10 concentrations were predicted based on land use and meteorology.•Meteorological factors were introduced to improve temporal resolution of LUR model.•A nonlinear relationship exists between meteorology and NO2 and PM10.
Chile is a tsunami-prone country. Since the 1960 Chilean earthquake triggered a Pacific-wide tsunami, there has been a considerable amount of research conducted on the geologic evidence for tsunamis ...along the coast of Chile. This review aims to gather all the evidence of tsunami inundation to identify which areas along the coast of Chile have been affected during modern, historical, and prehistoric times. This contributes to assessing the local and regional impacts of past events and helps to identify potential sites for further study. We seek to show the spatial and temporal distribution of tsunami deposits affected by their preservation in different climate zones. We also seek to assess the interpretation of each deposit by comparing information provided from a variety of sources and analyses. The review shows that thirty-one tsunamigenic events have been reported in historic times from 1570 CE to 2015 but deposits have only been found for twelve of these. There are ninety-two palaeotsunami deposits along Chile's coast and these span from the Miocene to Late Holocene. Geological evidence has been reported from fifty-seven sites of which 70% were found in southern Chile. While many deposits were identified in coastal lakes and river floodplains in southern Chile, tsunami deposits in the north are more commonly found on coastal plains, clifftops, and marshes. We also created a table assigning a level of certainty for each deposit. This is developed by the consideration of five criteria that include the use of multiproxy analyses, the correlation of a site with other deposits, comparisons with numerical simulations or historic counterparts, discrimination of the deposit from other possible processes, and a critical evaluation of the data in the original publication. This work provides insight into the types of environments that are most likely to contain evidence of past tsunamis and highlights the potential of finding more evidence in Chile of Pacific-wide “orphan tsunamis,” such as the 1420 CE event that inundated the coast of Japan. Altogether, this review reveals a high frequency of tsunamis on the Chilean coasts and indicates that in some areas ancient tsunamis have reached higher inundations than those reported in the historic record, therefore, these data should be considered in future tsunami modelling to be better prepared for future events.
Monitoring severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern (VOCs) is critical for public health management of coronavirus disease. Sequencing is resource-intensive ...and incompletely representative, and not all isolates can be sequenced. Because wastewater SARS-CoV-2 RNA concentrations correlate with coronavirus disease incidence in sewersheds, tracking VOCs through wastewater is appealing. We developed digital reverse transcription PCRs to monitor abundance of select mutations in Alpha and Delta VOCs in wastewater settled solids, applied these to July 2020-August 2021 samples from 2 large US metropolitan sewersheds, and compared results to estimates of VOC abundance from case isolate sequencing. Wastewater measurements tracked closely with case isolate estimates (Alpha, r
0.82-0.88; Delta, r
0.97). Mutations were detected in wastewater even at levels <5% of total SARS-CoV-2 RNA and in samples available 1-3 weeks before case isolate results. Wastewater variant monitoring should be strategically deployed to complement case isolate sequencing.
•This study introduced a novel comparative numerical modelling methodology using both forward (TELEMAC) and inverse (TSUFLIND) models to simulate the 2015 Illapel tsunami's impact in Chile ...accurately.•Most probable earthquake source parameters were estimated by comparing modelled tsunami hydrodynamics from TELEMAC with field observations.•Tsunami sediment deposits were used to estimate flow characteristics in the TSUFLIND model.•Both models, TELEMAC and TSUFLIND, yielded consistent results, validating the predicted tsunami flow depths, velocities, and sediment depositions.•The study highlights the importance of combining geological evidence with numerical models to enhance tsunami hazard assessment, especially when direct hydrodynamic measurements are unavailable.
The 2015 Illapel earthquake (Mw 8.3) generated a tsunami that significantly impacted the central-north Chilean coast. Previous studies have utilized numerical modelling to analyse this tsunami propagation, yet none have applied a comparative forward and inverse modelling approach to accurately estimate the earthquake source parameters, flow characteristics and sediment transport. A forward model TELEMAC was employed to simulate tsunami hydrodynamics and sediment transport, calibrating it against tide gauge records to identify the most accurate earthquake source scenario. Simultaneously, the inverse model TSUFLIND was utilized to deduce hydrodynamic properties during the inundation phase from sediment deposit characteristics. The performance of the models was evaluated by comparing flow characteristics. The approach was tested along the Tongoy estuary by comparing it against regional tide gauge data, alongside measurements of flow depth and run-up, and sediment deposit observations from five pits along the river (680 m to 1280 m inland). Along the five pits, TELEMAC results indicate the tsunami flow depths ranged between 3.22 m to 0.47 m, and onshore velocities ranged from 4.9 m/s to 2.21 m/s, with sediment deposition from 20 cm to 7 cm. On the other hand, TSUFLIND results were consistent with TELEMAC, with flow depths between 3.22 m to 0.68 m, velocities between 4.84 m/s to 2.05 m/s, and deposition thickness of 15 cm to 0.5 cm along the five pits. The agreement of the hydrodynamic results from both models highlights the importance of integrating geological evidence with numerical modelling where tide records or other hydrodynamic information cannot be obtained for tsunami events, highlighting the significance of a combined approach for advancing the understanding of tsunami hazards.
Abstract
Vaccination and nonpharmaceutical interventions (NPIs) reduce transmission of severe acute respiratory syndrome coronavirus 2 infection, but their effectiveness depends on coverage and ...adherence levels. We used scenario modeling to evaluate their effects on cases and deaths averted and herd immunity. NPIs and vaccines worked synergistically in different parts of the pandemic to reduce disease burden.
In March 2021, California implemented a vaccine equity policy that prioritized COVID-19 vaccine allocation to communities identified as least advantaged by an area-based socioeconomic measure, the ...Healthy Places Index. We conducted quasi-experimental and counterfactual analyses to estimate the effect of this policy on COVID-19 vaccination, case, hospitalization, and death rates. Among prioritized communities, vaccination rates increased 28.4 percent after policy implementation. Furthermore, an estimated 160,892 COVID-19 cases, 10,248 hospitalizations, and 679 deaths in the least-advantaged communities were averted by the policy. Despite these improvements, the share of COVID-19 cases, hospitalizations, and deaths in prioritized communities remained elevated. These estimates were robust in sensitivity analyses that tested exchangeability between prioritized communities and those not prioritized by the policy; model specifications; and potential temporal confounders, including prior infections. Correcting for disparities by strategically allocating limited resources to the least-advantaged or most-affected communities can reduce the impacts of COVID-19 and other diseases but might not eliminate health disparities.
The use of students’ within-school grade point average (GPA) ranking has emerged as a means to increase admission rates of both segregated minorities and high-performance individuals. Based on that ...idea, Chile’s centralized university admission system introduced, in 2012, a “GPA-ranking score” variable. In contrast to other ranking-based criteria, the Chilean version ostensibly avoids classmate competition by basing scores on past cohorts’ GPAs. Also, the GPA-ranking is similar to an added bonus to the GPA score, and it does not replace the national admission exam. Such design incentivizes both academic effort and GPA inflation. In this paper, we analyze the effects of the Chilean reform on GPA and achievement. Our results, based on difference-in-differences and simulated instruments methods, suggest that: (i) GPA increased across the entire distribution of students; (ii) GPA increases were larger in schools where the new variable presented greater incentives; and (iii) GPA increases were unrelated to improvements in achievement. We interpret the results as evidence that the Chilean ranking variable caused GPA inflation rather than increased learning.
The development of healthcare services for dementia is key to improving access to care and post-diagnostic support for people living with dementia. Memory Units have emerged as a new healthcare ...service composed of multidisciplinary teams with the goal of improving diagnosis and/or management of dementia patients. The main objective of this study was to describe and evaluate the Reach and Effectiveness of a Memory Unit in a public hospital in Chile, using the RE-AIM model, a multi-component model that allows for the evaluation of the implementation of ongoing healthcare programs. Regarding “R” (Reach): from March 2018 up to June 2019, a total of 510 patients were referred and assessed. Most patients came from primary care (51.9%) and from outpatient services at the Hospital Salvador (39.2%), particularly from the Neurology (63.3%) and Psychiatry (16.0%) departments. We estimated that our Memory Unit assessed 5.39% of all of the dementia patients living in the area of referral. With respect to “E” (Effectiveness): 419 patients are still being followed up at the Memory Unit. Ninety-one patients (18%) were discharged. Of these, 55 (66%) were referred to primary healthcare, 28 (31%) to other outpatient services, 9 (10%) to a specialized mental healthcare center, and 9 (10%) to a daycare center. Due to the short period of time that the Memory Unit has been operating, no other RE-AIM dimensions could be evaluated at this juncture. To our knowledge, this is the first implementation study of a Memory Unit in Latin America, and the first using the RE-AIM model. Although cultural differences worldwide might play a role in the lack of international guidelines, the publication of the experience of the first year of this unit in Chile could inform new countries about this process. Ongoing challenges include continuing to collect data to complement the RE-AIM evaluation and developing a protocol that can be adopted elsewhere in Chile and Latin America. Further studies are needed to assess the benefits of a Memory Unit in comparison to regular care and to develop a model that assures continuity and coordination of care for people with dementia.
PDF
