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1.
J Fish Biol ; 2024 Jul 04.
Article in English | MEDLINE | ID: mdl-38964773

ABSTRACT

Meristic characters are often used to differentiate between closely related forms, morphs, and species of fishes, and lend insight into ecology and post-glacial recolonization in taxa with complicated or contentious phylogenies, including the genus Salvelinus. Previous studies of meristics in Salvelinus have focused mostly on individual populations. We collated data from 456 populations/systems across the North American and Russian Arctic and sub-Arctic, and found that counts of pyloric caeca and gill rakers differed consistently between fish visually and/or genetically identified as Arctic char and Dolly Varden across their distributional ranges.

2.
Oecologia ; 202(3): 601-616, 2023 Jul.
Article in English | MEDLINE | ID: mdl-37488308

ABSTRACT

Within and among species variation in trophic and habitat shifts with body size can indicate the potential adaptive capacity of species to ecosystem change. In Arctic coastal ecosystems, which experience dramatic seasonal shifts and are undergoing rapid change, quantifying the trophic flexibility of coastal fishes with different migratory tactics has received limited attention. We examined the relationships among body length and condition (Fulton's K, phase angle from Bioelectrical Impedance Analysis) with trophic and habitat shifts (differences in δ15N and δ13C between blood tissues with different turnover rates) of two abundant and culturally important species, anadromous Arctic char (Salvelinus alpinus, n = 38) and sedentary Greenland cod (Gadus ogac, n = 65) during summer in coastal marine waters near Ulukhaktok, Northwest Territories, Canada. Habitat shifts (δ13C) increased with length (i.e., pelagic to benthic-littoral) and crossed-equilibrium (zero) at mid-sizes for both species. Seasonal trophic shifts (δ15N) were generally positive (i.e., increasing trophic level) for Arctic char and negative for Greenland cod. As hypothesised, intra-individual variation in size-based trophic shifts (δ15N-length residuals) increased with length for Arctic char. However, there were no trends with length in Greenland cod. Our findings highlight the importance of flexibility through ontogeny and mobility for Arctic char, whereas Greenland cod were generalist to localized prey and habitat across all sizes. The significant effect of body condition (phase angle) on size-based trophic shifts in Arctic char, and size-based habitat shifts in Greenland cod, highlight the potential trade-offs of contrasting life history strategies and capacity for ontogenetic niche plasticity.


Subject(s)
Ecosystem , Nutritional Status , Animals , Arctic Regions , Canada , Trout
3.
Soc Networks ; 72: 108-120, 2023 Jan.
Article in English | MEDLINE | ID: mdl-36188126

ABSTRACT

COVID-19 has resulted in dramatic and widespread social network interventions across the globe, with public health measures such as distancing and isolation key epidemiological responses to minimize transmission. Because these measures affect social interactions between people, the networked structure of daily lives is changed. Such largescale changes to social structures, present simultaneously across many different societies and touching many different people, give renewed significance to the conceptualization of social network interventions. As social network researchers, we need a framework for understanding and describing network interventions consistent with the COVID-19 experience, one that builds on past work but able to cast interventions across a broad societal framework. In this theoretical paper, we extend the conceptualization of social network interventions in these directions. We follow Valente (2012) with a tripartite categorization of interventions but add a multilevel dimension to capture hierarchical aspects that are a key feature of any society and implicit in any network. This multilevel dimension distinguishes goals, actions, and outcomes at different levels, from individuals to the whole of the society. We illustrate this extended taxonomy with a range of COVID-19 public health measures of different types and at multiple levels, and then show how past network intervention research in other domains can also be framed in this way. We discuss what counts as an effective network, an effective intervention, plausible causality, and careful selection and evaluation, as central to a full theory of network interventions.

4.
Biostatistics ; 22(4): 873-889, 2021 10 13.
Article in English | MEDLINE | ID: mdl-32061081

ABSTRACT

In screening applications involving low-prevalence diseases, pooling specimens (e.g., urine, blood, swabs, etc.) through group testing can be far more cost effective than testing specimens individually. Estimation is a common goal in such applications and typically involves modeling the probability of disease as a function of available covariates. In recent years, several authors have developed regression methods to accommodate the complex structure of group testing data but often under the assumption that covariate effects are linear. Although linearity is a reasonable assumption in some applications, it can lead to model misspecification and biased inference in others. To offer a more flexible framework, we propose a Bayesian generalized additive regression approach to model the individual-level probability of disease with potentially misclassified group testing data. Our approach can be used to analyze data arising from any group testing protocol with the goal of estimating multiple unknown smooth functions of covariates, standard linear effects for other covariates, and assay classification accuracy probabilities. We illustrate the methods in this article using group testing data on chlamydia infection in Iowa.


Subject(s)
Chlamydia Infections , Bayes Theorem , Chlamydia Infections/diagnosis , Humans , Mass Screening , Prevalence , Regression Analysis
5.
J Fish Biol ; 101(6): 1441-1451, 2022 Dec.
Article in English | MEDLINE | ID: mdl-36097690

ABSTRACT

Variable resource use and responses to environmental conditions can lead to phenotypic diversity and distinct morphotypes within salmonids, including Arctic char (Salvelinus alpinus). Despite the cultural and economic importance of Arctic char in the Inuvialuit Settlement Region (ISR), limited data exist on the extent and presence of morphological diversity in this region. This is of concern for management given climate change impacts on regional fish populations. The authors investigated morphological diversity in anadromous Arctic char sampled during their summer marine migration-residency period when seasonal harvesting occurs in a coastal mixed-stock fishery. Geometric morphometric analysis was conducted using digital photographs of live Arctic char (n = 103) of which a sub-set was subsequently implanted with acoustic transmitters (n = 90) and released, and their overwintering lakes determined using active acoustic telemetry surveys. Twenty-three morphological landmarks were established and overlaid on digital images, and nine linear measurements of the body and head were recorded. Principle component analysis and K-means clustering based on linear measurements categorised fish into three morphotypes: slender body and slim head (n = 31), small and short head with a small mouth (n = 46) and elongated head shape with large mouth (n = 26). Tagged individuals of the three morphotypes occupied all lakes with no distinction observed. The three Arctic char morphotypes detected in this coastal mixed-stock fishery could represent adaptation to specific feeding-movement behaviours potentially tied to juvenile residency in freshwater systems, efficient exploitation of the marine prey pulse, or are relicts from ancestral types. To the authors' knowledge, this study is the first to identify distinct Arctic char morphotypes occurring in sympatry in the marine environment. Identifying phenotypic diversity will assist management to promote the sustainability of this regional fishery.


Subject(s)
Water Pollutants, Chemical , Animals , Water Pollutants, Chemical/analysis , Trout , Lakes , Climate Change , Seasons , Arctic Regions
6.
Ophthalmic Plast Reconstr Surg ; 36(4): 395-398, 2020.
Article in English | MEDLINE | ID: mdl-31868788

ABSTRACT

PURPOSE: It has been demonstrated the pedicle of a tarsoconjunctival flap advancement does not appear to supply the flap itself and the vascularization of the remaining eyelid/tear film is thought to offer adequate nourishment for survival of the flap; as such, a swine model was constructed to assess the viability of a bilamellar autograft for repair of large full-thickness eyelid defects. METHODS: Full-thickness defects of varying sizes were created in each lower eyelid of 4 Yorkshire/Yorkshire crossed swine. The defects were then closed with a full-thickness ipsilateral graft from the upper eyelid. Large full-thickness defects were then created in the upper and lower eyelids of 8 Yorkshire/Yorkshire crossed swine and closed with bilamellar autografts from the contralateral eyelids. The subjects were then monitored postoperatively and assessed clinically for graft viability at postoperative days 1, 7, and 30. At the conclusion of the 30-day postoperative monitoring period, necropsy was performed and histopathologic analysis utilized to assess cell morphology and vessel ingrowth of the graft sites. RESULTS: In total, 28 full-thickness bilamellar grafts were constructed and examined. At the conclusion of the postoperative monitoring period, 27 of the grafts were deemed clinically viable and vascular ingrowth was determined to be equivalent to unaffected eyelid sections by histopathologic analysis. One case of postoperative hematoma was noted in the failed graft. One case of postoperative wound dehiscence required subsequent surgical repair. No clinically significant notching of the graft sites was noted. No cases of wound infection, corneal decompensation, or forniceal shortening were identified. CONCLUSIONS: This analysis demonstrates the viability of a full-thickness bilamellar autograft as a surgical alternative in the repair of large full-thickness eyelid defects in a porcine model. The postoperative outcomes are consistent with the recent literature. Additional studies need to be performed to assess the procedure's clinical utility in human subjects before incorporation into clinical practice.


Subject(s)
Blepharoplasty , Eyelid Neoplasms , Plastic Surgery Procedures , Animals , Autografts , Eyelid Neoplasms/surgery , Eyelids/surgery , Humans , Surgical Flaps , Sus scrofa , Swine
7.
Ophthalmic Plast Reconstr Surg ; 34(3): e90-e91, 2018.
Article in English | MEDLINE | ID: mdl-29494378

ABSTRACT

Fibrous histiocytoma is a soft tissue tumor with cells resembling both fibroblasts and histiocytes. Occasionally in the orbit, they rarely arise in the lacrimal sac. Similar to prior cases described, the patient presented with symptoms of epiphora and a slowly enlarging mass inferior to the right medial canthus. Imaging demonstrated a circumscribed 1.2 cm × 1.1 cm × 1.1 cm mass within the lacrimal sac without surrounding bony destruction. Grossly, the tumor appeared homogenous and rubbery. Pathologic study results from the case demonstrated zones of hypercellularity and hypocellularity with a fibrous appearance, admixed with spindle cells and collections of foamy histiocytes. A diagnosis of benign fibrous histiocytoma was rendered, with the patient experiencing a complete resolution of symptoms at subsequent follow up. To the authors' knowledge, this is the first reported solitary case report of a fibrous histiocytoma of the lacrimal sac in a pediatric patient.


Subject(s)
Eye Neoplasms/pathology , Histiocytoma, Benign Fibrous/pathology , Lacrimal Apparatus/pathology , Child , Humans , Male
8.
Stat Med ; 36(15): 2363-2377, 2017 07 10.
Article in English | MEDLINE | ID: mdl-28349583

ABSTRACT

As a cost-efficient data collection mechanism, the process of assaying pooled biospecimens is becoming increasingly common in epidemiological research; for example, pooling has been proposed for the purpose of evaluating the diagnostic efficacy of biological markers (biomarkers). To this end, several authors have proposed techniques that allow for the analysis of continuous pooled biomarker assessments. Regretfully, most of these techniques proceed under restrictive assumptions, are unable to account for the effects of measurement error, and fail to control for confounding variables. These limitations are understandably attributable to the complex structure that is inherent to measurements taken on pooled specimens. Consequently, in order to provide practitioners with the tools necessary to accurately and efficiently analyze pooled biomarker assessments, herein, a general Monte Carlo maximum likelihood-based procedure is presented. The proposed approach allows for the regression analysis of pooled data under practically all parametric models and can be used to directly account for the effects of measurement error. Through simulation, it is shown that the proposed approach can accurately and efficiently estimate all unknown parameters and is more computational efficient than existing techniques. This new methodology is further illustrated using monocyte chemotactic protein-1 data collected by the Collaborative Perinatal Project in an effort to assess the relationship between this chemokine and the risk of miscarriage. Copyright © 2017 John Wiley & Sons, Ltd.


Subject(s)
Biomarkers/analysis , Regression Analysis , Abortion, Spontaneous/blood , Abortion, Spontaneous/etiology , Bias , Biostatistics , Chemokine CCL2/blood , Computer Simulation , Female , Humans , Likelihood Functions , Models, Statistical , Monte Carlo Method , Pregnancy , Risk Factors
9.
Biom J ; 58(4): 944-61, 2016 Jul.
Article in English | MEDLINE | ID: mdl-26927583

ABSTRACT

There is a need for epidemiological and medical researchers to identify new biomarkers (biological markers) that are useful in determining exposure levels and/or for the purposes of disease detection. Often this process is stunted by high testing costs associated with evaluating new biomarkers. Traditionally, biomarker assessments are individually tested within a target population. Pooling has been proposed to help alleviate the testing costs, where pools are formed by combining several individual specimens. Methods for using pooled biomarker assessments to estimate discriminatory ability have been developed. However, all these procedures have failed to acknowledge confounding factors. In this paper, we propose a regression methodology based on pooled biomarker measurements that allow the assessment of the discriminatory ability of a biomarker of interest. In particular, we develop covariate-adjusted estimators of the receiver-operating characteristic curve, the area under the curve, and Youden's index. We establish the asymptotic properties of these estimators and develop inferential techniques that allow one to assess whether a biomarker is a good discriminator between cases and controls, while controlling for confounders. The finite sample performance of the proposed methodology is illustrated through simulation. We apply our methods to analyze myocardial infarction (MI) data, with the goal of determining whether the pro-inflammatory cytokine interleukin-6 is a good predictor of MI after controlling for the subjects' cholesterol levels.


Subject(s)
Biomarkers/analysis , Biometry/methods , Diagnostic Techniques and Procedures/standards , Humans , Interleukin-6/blood , Myocardial Infarction/diagnosis , ROC Curve
10.
Stat Med ; 34(27): 3606-21, 2015 Nov 30.
Article in English | MEDLINE | ID: mdl-26173957

ABSTRACT

Group testing, through the use of pooling, has been widely implemented as a more efficient means to screen individuals for infectious diseases. Typically, in these settings, practitioners are tasked with the complimentary goals of both case identification and estimation. For these purposes, many group testing strategies have been proposed, which address issues such as preserving anonymity in estimation studies, quality control, and classification. In general, these strategies require that a significant number of the individuals be retested, either in pools or individually. In order to provide practitioners with a general methodology that can be used to accurately and precisely analyze data of this form, herein, we propose a binary regression framework that can incorporate data arising from any group testing strategy. Further, we relax previously made assumptions regarding testing error rates by relating the diagnostic testing results to the latent biological marker levels of the individuals being tested. We investigate the finite sample performance of our proposed methodology through simulation and by applying our techniques to hepatitis B data collected as part of a study involving Irish prisoners.


Subject(s)
Bias , Mass Screening , Regression Analysis , Biomarkers , Biostatistics , Communicable Diseases/diagnosis , Computer Simulation , Humans , Mass Screening/methods , Mass Screening/statistics & numerical data , Models, Statistical , Sensitivity and Specificity
11.
Aust N Z J Psychiatry ; 49(8): 706-13, 2015 Aug.
Article in English | MEDLINE | ID: mdl-25586750

ABSTRACT

OBJECTIVE: Research has established the mental health sequelae following disaster, with studies now focused on understanding factors that mediate these outcomes. This study focused on anger, alcohol, subsequent life stressors and traumatic events as mediators in the development of mental health disorders following the 2009 Black Saturday Bushfires, Australia's worst natural disaster in over 100 years. METHOD: This study examined data from 1017 (M = 404, F = 613) adult residents across 25 communities differentially affected by the fires and participating in the Beyond Bushfires research study. Data included measures of fire exposure, posttraumatic stress disorder, depression, alcohol abuse, anger and subsequent major life stressors and traumatic events. Structural equation modeling assessed the influence of factors mediating the effects of fire exposure on mental health outcomes. RESULTS: Three mediation models were tested. The final model recorded excellent fit and observed a direct relationship between disaster exposure and mental health outcomes (b = .192, p < .001) and mediating relationships via Anger (b = .102, p < .001) and Major Life Stressors (b = .128, p < .001). Each gender was compared with multiple group analyses and while the mediation relationships were still significant for both genders, the direct relationship between exposure and outcome was no longer significant for men (p = .069), but remained significant (b = .234, p < .001) for women. CONCLUSIONS: Importantly, anger and major life stressors mediate the relationship between disaster exposure and development of mental health problems. The findings have significant implications for the assessment of anger post disaster, the provision of targeted anger-focused interventions and delivery of government and community assistance and support in addressing ongoing stressors in the post-disaster context to minimize subsequent mental health consequences.


Subject(s)
Anger , Disasters , Fires , Life Change Events , Mental Health , Stress, Psychological/psychology , Female , Humans , Male , Middle Aged , Risk Factors , Victoria
12.
J Phys Chem C Nanomater Interfaces ; 128(7): 2876-2883, 2024 Feb 22.
Article in English | MEDLINE | ID: mdl-38414836

ABSTRACT

Single-atom catalysts (SACs) of embedding an active metal in nitrogen-doped graphene are emergent catalytic materials in various applications. The rational design of efficient SACs necessitates an electronic and mechanistic understanding of those materials with reliable quantum mechanical simulations. Conventional computational methods of modeling SACs involve using an infinite slab model with periodic boundary condition, limiting to the selection of generalized gradient approximations as the exchange correlation (XC) functional within density functional theory (DFT). However, these DFT approximations suffer from electron self-interaction error and delocalization error, leading to errors in predicted charge-transfer energetics. An alternative strategy is using a molecular flake model, which carved out the important catalytic center by cleaving C-C bonds and employing a hydrogen capping scheme to saturate the innocent dangling bonds at the molecular boundary. By doing so, we can afford more accurate hybrid XC functionals, or even high-level correlated wavefunction theory, to study those materials. In this work, we compared the structural, electronic, and catalytic properties of SACs simulated using molecular flake models and periodic slab models with first-row transition metals as the active sites. Molecular flake models successfully reproduced structural properties, including both global distortion and local metal-coordination environment, as well as electronic properties, including spin magnetic moments and metal partial charges, for all transition metals studied. In addition, we calculated CO binding strength as a descriptor for electrochemical CO2 reduction reactivity and noted qualitatively similar trends between two models. Using the computationally efficient molecular flake models, we investigated the effect of tuning Hartree-Fock exchange in a global hybrid functional on the CO binding strength and observed system-dependent sensitivities. Overall, our calculations provide valuable insights into the development of accurate and efficient computational tools to simulate SACs.

13.
BJPsych Open ; 10(2): e57, 2024 Mar 04.
Article in English | MEDLINE | ID: mdl-38433588

ABSTRACT

BACKGROUND: Although much is known about psychopathology such as post-traumatic stress disorder (PTSD) and depression following bushfire (also known as wildfire), little is known about prevalence, trajectory and impacts for those experiencing general adjustment difficulties following exposure to these now-common events. AIMS: This was an exploratory analysis of a large cohort study that examined the prevalence, trajectory and risk factors of probable adjustment disorder over a 10-year period following bushfire exposure. METHOD: The Beyond Bushfires study assessed individuals exposed to a large and deadly bushfire across three time points spanning 10 years. Self-report survey data from participants from areas with moderate and high levels of fire-affectedness were analysed: n = 802 participants at Wave 1 (3-4 years post-fires), n = 596 at Wave 2 (5 years post-fires) and n = 436 at Wave 3 (10 years post-fires). Surveys indexed fire-related experiences and post-fire stressors, and comprised the six-item Kessler Psychological Distress Scale (probable adjustment disorder index), four-item Posttraumatic Stress Disorder Checklist (probable fire-related PTSD) and nine-item Patient Health Questionnaire (probable major depressive episode). RESULTS: Prevalence of probable adjustment disorder was 16% (Wave 1), 15% (Wave 2) and 19% (Wave 3). Probable adjustment disorder at 3-4 years post-fires predicted a five-fold increase in risk for escalating to severe psychiatric disorder (i.e. probable fire-related PTSD/major depressive episode) at 10 years post-fires, and was associated with post-fire income and relationship stressors. CONCLUSIONS: Adjustment difficulties are prevalent post-disaster, many of which are maintained and exacerbated over time, resulting in increased risk for later disorder and adaptation difficulties. Psychosocial interventions supporting survivors with adjustment difficulties may prevent progression to more severe disorder.

14.
BMJ Open ; 14(1): e076907, 2024 01 12.
Article in English | MEDLINE | ID: mdl-38216183

ABSTRACT

INTRODUCTION: Longitudinal studies can provide timely and accurate information to evaluate and inform COVID-19 control and mitigation strategies and future pandemic preparedness. The Optimise Study is a multidisciplinary research platform established in the Australian state of Victoria in September 2020 to collect epidemiological, social, psychological and behavioural data from priority populations. It aims to understand changing public attitudes, behaviours and experiences of COVID-19 and inform epidemic modelling and support responsive government policy. METHODS AND ANALYSIS: This protocol paper describes the data collection procedures for the Optimise Study, an ongoing longitudinal cohort of ~1000 Victorian adults and their social networks. Participants are recruited using snowball sampling with a set of seeds and two waves of snowball recruitment. Seeds are purposively selected from priority groups, including recent COVID-19 cases and close contacts and people at heightened risk of infection and/or adverse outcomes of COVID-19 infection and/or public health measures. Participants complete a schedule of monthly quantitative surveys and daily diaries for up to 24 months, plus additional surveys annually for up to 48 months. Cohort participants are recruited for qualitative interviews at key time points to enable in-depth exploration of people's lived experiences. Separately, community representatives are invited to participate in community engagement groups, which review and interpret research findings to inform policy and practice recommendations. ETHICS AND DISSEMINATION: The Optimise longitudinal cohort and qualitative interviews are approved by the Alfred Hospital Human Research Ethics Committee (# 333/20). The Optimise Study CEG is approved by the La Trobe University Human Ethics Committee (# HEC20532). All participants provide informed verbal consent to enter the cohort, with additional consent provided prior to any of the sub studies. Study findings will be disseminated through public website (https://optimisecovid.com.au/study-findings/) and through peer-reviewed publications. TRIAL REGISTRATION NUMBER: NCT05323799.


Subject(s)
COVID-19 , Adult , Humans , COVID-19/prevention & control , SARS-CoV-2 , Longitudinal Studies , Quarantine , Australia
15.
Polar Biol ; 44(7): 1353-1364, 2021.
Article in English | MEDLINE | ID: mdl-34720375

ABSTRACT

Populations of northern Dolly Varden (Salvelinus malma malma) exhibit partial seaward migration, yet little is known about this phenomenon in Dolly Varden populations. Our study analyzed data from three different Dolly Varden populations in the western Canadian Arctic in order to determine if: (1) differences in size-at-first seaward migration exist between fish that migrate at early and late ages among populations inhabiting different river systems, and (2) annual growth influences anadromous or resident life history choice. Otolith strontium analysis and back-calculation were used to determine age- and size-at-first seaward migration, respectively. Differences in age- and size-at-first seaward migration were determined across river system and migration age. Back-calculated fish lengths were compared using a mixed effect model to determine how early growth influences migratory tactics (early or late aged smolt, or resident). Our results indicate that fish exhibiting faster early growth migrated in earlier years and at smaller sizes than slower growing fish, however size- and age-at first seaward migration varied by river system. Faster growing Dolly Varden tended to become either residents or early smolts, while slower growth was associated with smolting later in life. This is contrary to life history theory where the fastest growing fish in a population should mature as a resident. Our results indicate factors other than growth may be influencing life history 'decisions' in Dolly Varden. Future work on growth efficiencies and metabolic rates is needed to assess how they affect migratory behaviours.

16.
Ecol Evol ; 11(3): 1457-1475, 2021 Feb.
Article in English | MEDLINE | ID: mdl-33598144

ABSTRACT

In a polyphenic species, differences in resource use are expected among ecotypes, and homogeneity in resource use is expected within an ecotype. Yet, using a broad resource spectrum has been identified as a strategy for fishes living in unproductive northern environments, where food is patchily distributed and ephemeral. We investigated whether specialization of trophic resources by individuals occurred within the generalist piscivore ecotype of lake trout from Great Bear Lake, Canada, reflective of a form of diversity. Four distinct dietary patterns of resource use within this lake trout ecotype were detected from fatty acid composition, with some variation linked to spatial patterns within Great Bear Lake. Feeding habits of different groups within the ecotype were not associated with detectable morphological or genetic differentiation, suggesting that behavioral plasticity caused the trophic differences. A low level of genetic differentiation was detected between exceptionally large-sized individuals and other piscivore individuals. We demonstrated that individual trophic specialization can occur within an ecotype inhabiting a geologically young system (8,000-10,000 yr BP), a lake that sustains high levels of phenotypic diversity of lake trout overall. The characterization of niche use among individuals, as done in this study, is necessary to understand the role that individual variation can play at the beginning of differentiation processes.

17.
Sci Rep ; 10(1): 14973, 2020 09 11.
Article in English | MEDLINE | ID: mdl-32917923

ABSTRACT

Thrombosis and infections are two grave, interrelated problems associated with the use of central venous catheters (CVL). Currently used antibiotic coated CVL has limited clinical success in resisting blood stream infection and may increase the risk of emerging antibiotic resistant strains. We report an antibiotic-free, fluoropolymer-immobilized, liquid perfluorocarbon-coated peripherally inserted central catheter (PICC) line and its effectiveness in reducing catheter associated thrombosis and pathogen colonization, as an alternative to antibiotic coated CVL. Commercially available polyurethane PICC catheter was modified by a three-step lamination process, with thin fluoropolymer layers to yield fluoropolymer-polyurethane-fluoropolymer composite structure before applying the liquid perfluorocarbon (LP). This high throughput process of modifying commercial PICC catheters with fluoropolymer is quicker, safer and shows higher thromboresistance than fluorinated, omniphobic catheter surfaces, produced by previously reported self-assembled monolayer deposition techniques. The LP immobilized on the fluoropolymer is highly durable in physiological flow conditions for over 60 days and continue to resist Staphylococcus colonization.


Subject(s)
Blood Coagulation/drug effects , Catheter-Related Infections/prevention & control , Catheterization, Central Venous , Central Venous Catheters , Fluorocarbons/pharmacology , Thrombosis/prevention & control , Animals , Fluorocarbons/chemistry , Humans , Sheep , Thrombosis/etiology
18.
Commun Stat Theory Methods ; 48(5): 1092-1107, 2019.
Article in English | MEDLINE | ID: mdl-33635297

ABSTRACT

A robust regression methodology is proposed via M-estimation. The approach adapts to the tail behavior and skewness of the distribution of the random error terms, providing for a reliable analysis under a broad class of distributions. This is accomplished by allowing the objective function, used to determine the regression parameter estimates, to be selected in a data driven manner. The asymptotic properties of the proposed estimator are established and a numerical algorithm is provided to implement the methodology. The finite sample performance of the proposed approach is exhibited through simulation and the approach was used to analyze two motivating datasets.

19.
PLoS One ; 13(12): e0210202, 2018.
Article in English | MEDLINE | ID: mdl-30596778

ABSTRACT

Otolith strontium and multi-year mark-recapture information were used to characterize associations between migration patterns and spawning frequencies in an anadromous Dolly Varden (Salvelinus malma) population (Rat River, Northwest Territories, Canada) that undertakes a long migration between freshwater spawning/overwintering (Fish Creek; a tributary to Rat River) and marine feeding habitats (Beaufort Sea) (~800 km round trip). Reconstructions of lifetime annual migration histories among otolith annuli was matched to information on reproductive status (current-year 'spawner' or 'non-spawner') that was known in two different, sometimes successive, years for each fish. Two migratory life histories were observed: fish either migrated annually after smoltification or periodically skipped an annual ocean migration to remain in freshwater and spawn. Different spawning frequencies were detected where fish not migrating annually tended to spawn in alternate years (84.6%) more often than those migrating annually (50%). Additionally, annually migrating fish had lower longevity (≤9 years vs. ≤13 years). The evaluation of differences in spawning frequency between sexes, independent of migration tactic, revealed males (84.6%) skipped spawning more often than females (51.2%) suggesting fitness trade-offs between life histories differ between sexes. Further, some fish returned from the sea considerably earlier than the majority of other current-year migrants. Our findings demonstrate intrapopulation diversity in migration behaviour and reproductive frequency.


Subject(s)
Animal Migration/physiology , Fresh Water , Reproduction/physiology , Rivers , Trout/physiology , Animals , Arctic Regions , Female , Male
20.
Risk Manag Healthc Policy ; 11: 127-138, 2018.
Article in English | MEDLINE | ID: mdl-30214330

ABSTRACT

Psychotic spectrum disorders are serious illnesses with symptoms that significantly impact functioning and quality of life. An accumulating body of literature has demonstrated that specialized treatments that are offered early after symptom onset are disproportionately more effective in managing symptoms and improving outcomes than when these same treatments are provided later in the course of illness. Specialized, multicomponent treatment packages are of particular importance, which are comprised of services offered as soon as possible after the onset of psychosis with the goal of addressing multiple care needs within a single care setting. As specialized programs continue to develop worldwide, it is crucial to consider how to increase access to such specialized services. In the current review, we utilize an ecological model of understanding barriers to care, with emphasis on understanding how individuals with first-episode psychosis interact with and are influenced by a variety of systemic factors that impact help-seeking behaviors and engagement with treatment. Future work in this area will be important in understanding how to most effectively design and implement specialized care for individuals early in the course of a psychotic disorder.

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