Publications by authors named "Gary Parker"

35 Publications

The role of lateral erosion in the evolution of nondendritic drainage networks to dendricity and the persistence of dynamic networks.

Proc Natl Acad Sci U S A 2021 Apr;118(16)

Department of Civil and Environmental Engineering, University of Illinois Urbana-Champaign, Urbana, IL 61801;

Dendritic, i.e., tree-like, river networks are ubiquitous features on Earth's landscapes; however, how and why river networks organize themselves into this form are incompletely understood. A branching pattern has been argued to be an optimal state. Therefore, we should expect models of river evolution to drastically reorganize (suboptimal) purely nondendritic networks into (more optimal) dendritic networks. To date, current physically based models of river basin evolution are incapable of achieving this result without substantial allogenic forcing. Here, we present a model that does indeed accomplish massive drainage reorganization. The key feature in our model is basin-wide lateral incision of bedrock channels. The addition of this submodel allows for channels to laterally migrate, which generates river capture events and drainage migration. An important factor in the model that dictates the rate and frequency of drainage network reorganization is the ratio of two parameters, the lateral and vertical rock erodibility constants. In addition, our model is unique from others because its simulations approach a dynamic steady state. At a dynamic steady state, drainage networks persistently reorganize instead of approaching a stable configuration. Our model results suggest that lateral bedrock incision processes can drive major drainage reorganization and explain apparent long-lived transience in landscapes on Earth.
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http://dx.doi.org/10.1073/pnas.2015770118DOI Listing
April 2021

Development and implementation of guidelines for the management of depression: a systematic review.

Bull World Health Organ 2020 Oct 27;98(10):683-697H. Epub 2020 Aug 27.

School of Clinical Medicine, The University of Queensland, Brisbane, Australia.

Objective: To evaluate the development and implementation of clinical practice guidelines for the management of depression globally.

Methods: We conducted a systematic review of existing guidelines for the management of depression in adults with major depressive or bipolar disorder. For each identified guideline, we assessed compliance with measures of guideline development quality (such as transparency in guideline development processes and funding, multidisciplinary author group composition, systematic review of comparative efficacy research) and implementation (such as quality indicators). We compared guidelines from low- and middle-income countries with those from high-income countries.

Findings: We identified 82 national and 13 international clinical practice guidelines from 83 countries in 27 languages. Guideline development processes and funding sources were explicitly specified in a smaller proportion of guidelines from low- and middle-income countries (8/29; 28%) relative to high-income countries (35/58; 60%). Fewer guidelines (2/29; 7%) from low- and middle-income countries, relative to high-income countries (22/58; 38%), were authored by a multidisciplinary development group. A systematic review of comparative effectiveness was conducted in 31% (9/29) of low- and middle-income country guidelines versus 71% (41/58) of high-income country guidelines. Only 10% (3/29) of low- and middle-income country and 19% (11/58) of high-income country guidelines described plans to assess quality indicators or recommendation adherence.

Conclusion: Globally, guideline implementation is inadequately planned, reported and measured. Narrowing disparities in the development and implementation of guidelines in low- and middle-income countries is a priority. Future guidelines should present strategies to implement recommendations and measure feasibility, cost-effectiveness and impact on health outcomes.
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http://dx.doi.org/10.2471/BLT.20.251405DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7652558PMC
October 2020

How canyons evolve by incision into bedrock: Rainbow Canyon, Death Valley National Park, United States.

Proc Natl Acad Sci U S A 2020 06 15;117(26):14730-14737. Epub 2020 Jun 15.

Department of Civil & Environmental Engineering, University of Illinois Urbana-Champaign, Urbana, IL 61801;

Incising rivers may be confined by low-slope, erodible hillslopes or steep, resistant sidewalls. In the latter case, the system forms a canyon. We present a morphodynamic model that includes the essential elements of a canyon incising into a plateau, including 1) abrasion-driven channel incision, 2) migration of a canyon-head knickpoint, 3) sediment feed from an alluvial channel upstream of the knickpoint, and 4) production of sediment by sidewall collapse. We calculate incision in terms of collision of clasts with the bed. We calculate knickpoint migration using a moving-boundary formulation that allows a slope discontinuity where the channel head meets an alluvial plateau feeder channel. Rather than modeling sidewall collapse events, we model long-term behavior using a constant sidewall slope as the channel incises. Our morphodynamic model specifically applies to canyon, rather than river-hillslope evolution. We implement it for Rainbow Canyon, CA. Salient results are as follows: 1) Sediment supply from collapsing canyon sidewalls can be substantially larger than that supplied from the feeder channel on the plateau. 2) For any given quasi-equilibrium canyon bedrock slope, two conjugate slopes are possible for the alluvial channel upstream, with the lower of the two corresponding to a substantially lower knickpoint migration rate and higher preservation potential. 3) Knickpoint migration occurs at a substantially faster time scale than regrading of the bedrock channel itself, underlying the significance of disequilibrium processes. Although implemented for constant climactic conditions, the model warrants extension to long-term climate variation.
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http://dx.doi.org/10.1073/pnas.1911040117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7334490PMC
June 2020

The role of saltwater and waves in continental shelf formation with seaward migrating clinoform.

Proc Natl Acad Sci U S A 2020 01 7;117(3):1266-1273. Epub 2020 Jan 7.

Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801;

Continental shelves have generally been interpreted as drowned coastal plains associated with the allogenic effect of sea-level variation. Here, without disputing this mechanism we describe an alternative autogenic mechanism for subaqueous shelf formation, driven by the presence of dissolved salt in seawater and surface waves. We use a numerical model describing flow hydrodynamics, sediment transport, and morphodynamics in order to do this. More specifically, we focus on two major aspects: 1) the role of saltwater in the subaqueous construction of continental shelves and 2) the transformation of these shelves into seaward-migrating clinoforms under the condition of repeated pulses of water and sediment input and steady wave effects, but no allogenic forcing such as sea-level change. In the case for which the receiving basin contains fresh water of the same density as the sediment-laden river water, the hyperpycnal river water plunges to form a turbidity current that can run out to deep water. In the case for which the receiving basin contains sea water but the river contains sediment-laden fresh water, the hypopycnal river water forms a surface plume that deposits sediment proximally. This proximate proto-shelf can then grow to wave base, after which wave-supported turbidity currents can extend it seaward. The feature we refer to is synonymous with near-shore mud belts.
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http://dx.doi.org/10.1073/pnas.1909572117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6983424PMC
January 2020

Universal relation with regime transition for sediment transport in fine-grained rivers.

Proc Natl Acad Sci U S A 2020 01 18;117(1):171-176. Epub 2019 Dec 18.

Department of Civil and Environmental Engineering, Ven Te Chow Hydrosystems Laboratory, University of Illinois at Urbana-Champaign, IL 61801;

Fine-grained sediment (grain size under 2,000 μm) builds floodplains and deltas, and shapes the coastlines where much of humanity lives. However, a universal, physically based predictor of sediment flux for fine-grained rivers remains to be developed. Herein, a comprehensive sediment load database for fine-grained channels, ranging from small experimental flumes to megarivers, is used to find a predictive algorithm. Two distinct transport regimes emerge, separated by a discontinuous transition for median bed grain size within the very fine sand range (81 to 154 μm), whereby sediment flux decreases by up to 100-fold for coarser sand-bedded rivers compared to river with silt and very fine sand beds. Evidence suggests that the discontinuous change in sediment load originates from a transition of transport mode between mixed suspended bed load transport and suspension-dominated transport. Events that alter bed sediment size near the transition may significantly affect fluviocoastal morphology by drastically changing sediment flux, as shown by data from the Yellow River, China, which, over time, transitioned back and forth 3 times between states of high and low transport efficiency in response to anthropic activities.
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http://dx.doi.org/10.1073/pnas.1911225116DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6955285PMC
January 2020

Flow directionality of pristine meandering rivers is embedded in the skewing of high-amplitude bends and neck cutoffs.

Proc Natl Acad Sci U S A 2019 11 4;116(47):23448-23454. Epub 2019 Nov 4.

Department of Civil & Environmental Engineering, University of Illinois, Urbana, IL 61801;

Information concerning the dynamics of river meandering is embedded in their planforms. Here, we focus on how bend skewing varies with increasing sinuosity, and how flow direction is embedded in bend skewing. It has often been thought that upstream-skewed bends are dominant within a sufficiently long reach. These bends may allow a reasonable inference as to the direction of flow. Here we consider this issue using 20 reaches of freely meandering alluvial rivers that are in remote locations, generally far from human influence. We find that low-amplitude bends tend to be downstream-, rather than upstream-skewed. Bends with sinuosity greater than 2.6, however, are predominantly upstream-skewed. Of particular interest are the neck cutoffs, all chosen to be relatively recent according to their position related to the main channel: 84% of these are upstream-skewed. Neck cutoffs, which have likely evolved directly from bends of the highest sinuosity, represent the planform feature most likely to have flow direction embedded in them. The field data suggest that meander bends without external forcing such as engineering works tend to evolve from downstream-skewed low-sinuosity bends to upstream-skewed high-sinuosity bends before cutoff. This process can be reproduced, to some extent, using models coupling sedimentary dynamics with flow dynamics.
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http://dx.doi.org/10.1073/pnas.1910874116DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6876206PMC
November 2019

Process evaluation in the field: global learnings from seven implementation research hypertension projects in low-and middle-income countries.

BMC Public Health 2019 Jul 16;19(1):953. Epub 2019 Jul 16.

The George Institute for Global Health, UNSW, Sydney, Australia.

Background: Process evaluation is increasingly recognized as an important component of effective implementation research and yet, there has been surprisingly little work to understand what constitutes best practice. Researchers use different methodologies describing causal pathways and understanding barriers and facilitators to implementation of interventions in diverse contexts and settings. We report on challenges and lessons learned from undertaking process evaluation of seven hypertension intervention trials funded through the Global Alliance of Chronic Diseases (GACD).

Methods: Preliminary data collected from the GACD hypertension teams in 2015 were used to inform a template for data collection. Case study themes included: (1) description of the intervention, (2) objectives of the process evaluation, (3) methods including theoretical basis, (4) main findings of the study and the process evaluation, (5) implications for the project, policy and research practice and (6) lessons for future process evaluations. The information was summarized and reported descriptively and narratively and key lessons were identified.

Results: The case studies were from low- and middle-income countries and Indigenous communities in Canada. They were implementation research projects with intervention arm. Six theoretical approaches were used but most comprised of mixed-methods approaches. Each of the process evaluations generated findings on whether interventions were implemented with fidelity, the extent of capacity building, contextual factors and the extent to which relationships between researchers and community impacted on intervention implementation. The most important learning was that although process evaluation is time consuming, it enhances understanding of factors affecting implementation of complex interventions. The research highlighted the need to initiate process evaluations early on in the project, to help guide design of the intervention; and the importance of effective communication between researchers responsible for trial implementation, process evaluation and outcome evaluation.

Conclusion: This research demonstrates the important role of process evaluation in understanding implementation process of complex interventions. This can help to highlight a broad range of system requirements such as new policies and capacity building to support implementation. Process evaluation is crucial in understanding contextual factors that may impact intervention implementation which is important in considering whether or not the intervention can be translated to other contexts.
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http://dx.doi.org/10.1186/s12889-019-7261-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6651979PMC
July 2019

Bedrock-alluvial streams with knickpoint and plunge pool that migrate upstream with permanent form.

Sci Rep 2019 04 16;9(1):6176. Epub 2019 Apr 16.

Department of Civil & Environmental Engineering, University of Illinois Urbana-Champaign, Urbana, 61801, USA.

Purely alluvial rivers cannot sustain knickpoints along their long profiles, as they would be obliterated by diffusional morphodynamics. Bedrock streams with a partial alluvial cover, however, form and sustain slope breaks over long periods of time. Here we consider the case of an initial profile of a bedrock-alluvial stream with a sharp slope break, or knickpoint, from high to low midway. We show that if the initial flow is sufficiently Froude-supercritical in the upstream reach and Froude-subcritical in the downstream reach, a three-tiered structure can evolve at the slope break: a hydraulic jump at the water surface; a scour hole in the alluvium above the bedrock, and a plunge pool carved into bedrock. Once the profile adjusts to balance uplift, it can migrate upstream without changing form.
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http://dx.doi.org/10.1038/s41598-019-42389-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6467923PMC
April 2019

The role of context in implementation research for non-communicable diseases: Answering the 'how-to' dilemma.

PLoS One 2019 8;14(4):e0214454. Epub 2019 Apr 8.

School of Public Health, Imperial College London, London, United Kingdom.

Introduction: Understanding context and how this can be systematically assessed and incorporated is crucial to successful implementation. We describe how context has been assessed (including exploration or evaluation) in Global Alliance for Chronic Diseases (GACD) implementation research projects focused on improving health in people with or at risk of chronic disease and how contextual lessons were incorporated into the intervention or the implementation process.

Methods: Using a web-based semi-structured questionnaire, we conducted a cross-sectional survey to collect quantitative and qualitative data across GACD projects (n = 20) focusing on hypertension, diabetes and lung diseases. The use of context-specific data from project planning to evaluation was analyzed using mixed methods and a multi-layered context framework across five levels; 1) individual and family, 2) community, 3) healthcare setting, 4) local or district level, and 5) state or national level.

Results: Project teams used both qualitative and mixed methods to assess multiple levels of context (avg. = 4). Methodological approaches to assess context were identified as formal and informal assessments, engagement of stakeholders, use of locally adapted resources and materials, and use of diverse data sources. Contextual lessons were incorporated directly into the intervention by informing or adapting the intervention, improving intervention participation or improving communication with participants/stakeholders. Provision of services, equipment or information, continuous engagement with stakeholders, feedback for personnel to address gaps, and promoting institutionalization were themes identified to describe how contextual lessons are incorporated into the implementation process.

Conclusions: Context is regarded as critical and influenced the design and implementation of the GACD funded chronic disease interventions. There are different approaches to assess and incorporate context as demonstrated by this study and further research is required to systematically evaluate contextual approaches in terms of how they contribute to effectiveness or implementation outcomes.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0214454PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6453477PMC
December 2019

Task-shifting for cardiovascular risk factor management: lessons from the Global Alliance for Chronic Diseases.

BMJ Glob Health 2018 8;3(Suppl 3):e001092. Epub 2018 Nov 8.

Department of Medicine, Queen's University, Kingston, Ontario, Canada.

Task-shifting to non-physician health workers (NPHWs) has been an effective model for managing infectious diseases and improving maternal and child health. There is inadequate evidence to show the effectiveness of NPHWs to manage cardiovascular diseases (CVDs). In 2012, the Global Alliance for Chronic Diseases funded eight studies which focused on task-shifting to NPHWs for the management of hypertension. We report the lessons learnt from the field. From each of the studies, we obtained information on the types of tasks shifted, the professional level from which the task was shifted, the training provided and the challenges faced. Additionally, we collected more granular data on 'lessons learnt ' throughout the implementation process and 'design to implementation' changes that emerged in each project. The tasks shifted to NPHWs included screening of individuals, referral to physicians for diagnosis and management, patient education for lifestyle improvement, follow-up and reminders for medication adherence and appointments. In four studies, tasks were shifted from physicians to NPHWs and in four studies tasks were shared between two different levels of NPHWs. Training programmes ranged between 3 and 7 days with regular refresher training. Two studies used clinical decision support tools and mobile health components. Challenges faced included system level barriers such as inability to prescribe medicines, varying skill sets of NPHWs, high workload and staff turnover. With the acute shortage of the health workforce in low-income and middle-income countries (LMICs), achieving better health outcomes for the prevention and control of CVD is a major challenge. Task-shifting or sharing provides a practical model for the management of CVD in LMICs.
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http://dx.doi.org/10.1136/bmjgh-2018-001092DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6231102PMC
November 2018

Gaps in Guidelines for the Management of Diabetes in Low- and Middle-Income Versus High-Income Countries-A Systematic Review.

Diabetes Care 2018 05;41(5):1097-1105

National and Kapodistrian University of Athens, Athens, Greece.

Objective: The extent to which diabetes (DM) practice guidelines, often based on evidence from high-income countries (HIC), can be implemented to improve outcomes in low- and middle-income countries (LMIC) is a critical challenge. We carried out a systematic review to compare type 2 DM guidelines in individual LMIC versus HIC over the past decade to identify aspects that could be improved to facilitate implementation.

Research Design And Methods: Eligible guidelines were sought from online databases and websites of diabetes associations and ministries of health. Type 2 DM guidelines published between 2006 and 2016 with accessible full publications were included. Each of the 54 eligible guidelines was assessed for compliance with the Institute of Medicine (IOM) standards, coverage of the cardiovascular quadrangle (epidemiologic surveillance, prevention, acute care, and rehabilitation), translatability, and its target audiences.

Results: Most LMIC guidelines were inadequate in terms of applicability, clarity, and dissemination plan as well as socioeconomic and ethical-legal contextualization. LMIC guidelines targeted mainly health care providers, with only a few including patients (7%), payers (11%), and policy makers (18%) as their target audiences. Compared with HIC guidelines, the spectrum of DM clinical care addressed by LMIC guidelines was narrow. Most guidelines from the LMIC complied with less than half of the IOM standards, with 12% of the LMIC guidelines satisfying at least four IOM criteria as opposed to 60% of the HIC guidelines ( < 0.001).

Conclusions: A new approach to the contextualization, content development, and delivery of LMIC guidelines is needed to improve outcomes.
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http://dx.doi.org/10.2337/dc17-1795DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5911785PMC
May 2018

Facilitating access to surgical care through a decentralised case-finding strategy: experience in Madagascar.

BMJ Glob Health 2017 29;2(3):e000427. Epub 2017 Sep 29.

Department of Global Health and Social Medicine, Program in Global Surgery and Social Change, Harvard Medical School, Boston, Massachusetts, USA.

Over two-thirds of the world's population lack access to surgical care. Non-governmental organisation's providing free surgeries may overcome financial barriers, but other barriers to care still exist. This analysis paper discusses two different case-finding strategies in Madagascar that aimed to increase the proportion of poor patients, women and those for whom multiple barriers to care exist. From October 2014 to June 2015, we used a centralised selection strategy, aiming to find 70% of patients from the port city, Toamasina, and 30% from the national capital and two remote cities. From August 2015 to June 2016, a decentralised strategy was used, aiming to find 30% of patients from Toamasina and 70% from 11 remote locations, including the capital. Demographic information and self-reported barriers to care were collected. Wealth quintile was calculated for each patient using a combination of participant responses to asset-related and demographic questions, and publicly available data. A total of 2971 patients were assessed. The change from centralised to decentralised selection resulted in significantly poorer patients undergoing surgery. All reported barriers to prior care, except for lack of transportation, were significantly more likely to be identified in the decentralised group. Patients who identified multiple barriers to prior surgical care were less likely to be from the richest quintile (p=0.037) and more likely to be in the decentralised group (p=0.046). Our country-specific analysis shows that decentralised patient selection strategies may be used to overcome barriers to care and allow patients in greatest need to access surgical care.
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http://dx.doi.org/10.1136/bmjgh-2017-000427DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5640035PMC
September 2017

Clinical Outcome, Social Impact and Patient Expectation: a Purposive Sampling Pilot Evaluation of Patients in Benin Seven Years After Surgery.

World J Surg 2018 05;42(5):1254-1261

M/V Africa Mercy, Mercy Ships, Port Au Cotonou, Benin.

Background: Access to affordable and timely surgery is not equitable around the world. Five billion people lack access, and while non-governmental organizations (NGOs) help to meet this need, long-term surgical outcomes, social impact or patient experience is rarely reported.

Method: In 2016, Mercy Ships, a surgical NGO, undertook an evaluation of patients who had received surgery seven years earlier with Mercy Ships in 2009 in Benin. Using purposive sampling, patients who had received maxillofacial, plastics or orthopedic surgery were invited to attend a surgical evaluation day. In this pilot study, we used semi-structured interviews and questionnaire responses to assess patient expectation, surgical and social outcome.

Results: Our results show that seven years after surgery 35% of patients report surgery-related pain and 18% had sought further care for a clinical complication of their condition. However, 73% of patients report gaining social benefit from surgery, and overall patient satisfaction was 89%, despite 35% of patients saying that they were unclear what to expect after surgery indicating a mismatch of doctor/patient expectations and failure of the consent process.

Conclusion: In conclusion, our pilot study shows that NGO surgery in Benin provided positive social impact associated with complication rates comparable to high-income countries when assessed seven years later. Key areas for further study in LMICs are: evaluation and treatment of chronic pain, consent and access to further care.
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http://dx.doi.org/10.1007/s00268-017-4296-9DOI Listing
May 2018

The exceptional sediment load of fine-grained dispersal systems: Example of the Yellow River, China.

Sci Adv 2017 May 12;3(5):e1603114. Epub 2017 May 12.

Ven Te Chow Hydrosystems Laboratory, Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Champaign, IL 61801, USA.

Sedimentary dispersal systems with fine-grained beds are common, yet the physics of sediment movement within them remains poorly constrained. We analyze sediment transport data for the best-documented, fine-grained river worldwide, the Huanghe (Yellow River) of China, where sediment flux is underpredicted by an order of magnitude according to well-accepted sediment transport relations. Our theoretical framework, bolstered by field observations, demonstrates that the Huanghe tends toward upper-stage plane bed, yielding minimal form drag, thus markedly enhancing sediment transport efficiency. We present a sediment transport formulation applicable to all river systems with silt to coarse-sand beds. This formulation demonstrates a remarkably sensitive dependence on grain size within a certain narrow range and therefore has special relevance to silt-sand fluvial systems, particularly those affected by dams.
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http://dx.doi.org/10.1126/sciadv.1603114DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5429038PMC
May 2017

Gaps in Hypertension Guidelines in Low- and Middle-Income Versus High-Income Countries: A Systematic Review.

Hypertension 2016 12 3;68(6):1328-1337. Epub 2016 Oct 3.

From the Department of Medicine and University College Hospital (M.O., J.Y., T.M., L.O., T.F., E.S.M., B.S.) and Institute for Advanced Medical Research and Training, College of Medicine (R.A.), University of Ibadan, Nigeria; WFNR-Blossom Specialist Medical Center, Ibadan, Nigeria (M.O., E.U.); Federal Teaching Hospital, Ido-Ekiti, Nigeria (P.O.); Department of Medicine, CRONICAS Center of Excellence in Chronic Diseases, Universidad Peruana Cayetano Heredia, Lima, Peru (J.J.M.); Department of Neurology (W.F., R.S., B.O.) and Department of Public Health Sciences (M.G.), Medical University of South Carolina, Charleston; School of International Development and Global Studies, University of Ottawa, Ontario, Canada (S.Y.); Department of Family and Emergency Medicine, University of Montreal, Quebec, Canada (J.K.); Department of Public Health, Health Service Organization, Hamilton, Ontario, Canada (L.T.); Departments of Anesthesia/Pediatrics, McMaster University, Hamilton, Ontario, Canada (J.V.O.); Department of Health Research, Ministry of Health & Family Welfare, Government of India, New Delhi, India (P.M.); Sydney Medical School, University of Sydney, New South Wales, Australia (C.C., R.J.); Non Communicable Diseases Research Unit, South African Medical Research Council, Tygerberg, South Africa (A.K.); School of Clinical Sciences at Monash Health, Monash University, Clayton, Victoria, Australia (A.G.T.); Cardiovascular Global Health Division of Cardiology, Duke University Medical Center, Durham, NC (G.S.B.); Global Alliance for Chronic Diseases, UCL Institute for Global Health, London, United Kingdom (G.P.); Department of Public Health, Academic Medical Centre, University of Amsterdam, The Netherlands (C.A.); Department of Experimental and Clinical Medicine, University of Florence, Italy (P.A.M.); and Developmental Pathways for Health Research Unit, University of the Witwatersrand, Johannesburg, South Africa (S.N.).

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http://dx.doi.org/10.1161/HYPERTENSIONAHA.116.08290DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5159303PMC
December 2016

Barriers to Surgical Care and Health Outcomes: A Prospective Study on the Relation Between Wealth, Sex, and Postoperative Complications in the Republic of Congo.

World J Surg 2017 Jan;41(1):14-23

Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, 243 Charles St, Boston, MA, 02114, USA.

Background: Approximately thirty percent of the global burden of disease is comprised of surgical conditions. However, five billion people lack access to surgery, with complex factors acting as barriers. We examined whether patient demographics predict barriers to care, and the relation between these factors and postoperative complications in a prospective cohort.

Methods: Participants included people presenting to a global charity in Republic of Congo with a surgical condition between August 2013 and May 2014. The outcomes were self-reported barrier to care and postoperative complications documented by medical record. Logistic regression was used to adjust for covariates.

Results: Of 1237 patients in our study, 1190 (96.2 %) experienced a barrier to care and 126 (10.2 %) experienced a postoperative complication. The most frequently reported barrier was cost (73 %), followed by lack of provider (8.2 %). Greater wealth was associated with decreased odds of cost as a barrier (OR 0.72 [0.57, 0.90]). Greater wealth (OR 1.52 [1.03, 2.25]) and rural home location (OR 3.35 [1.16, 9.62]) were associated with increased odds of no surgeon being available. Cost as a barrier (OR 2.82 [1.02, 7.77]), female sex (OR 3.45 [1.62, 7.33]), and lack of surgeon (OR 5.62 [1.68, 18.77]) were associated with increased odds of postoperative complication. Patient wealth was not associated with odds of postoperative complication.

Conclusions: Barriers to surgery were common in Republic of Congo. Patient wealth and home location may predict barriers to surgery. Addressing gender disparities, access to providers, and patient perception of barriers in addition to removal of barriers may help maximize patient health benefits.
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http://dx.doi.org/10.1007/s00268-016-3676-xDOI Listing
January 2017

Relationships Between Caregiver Violence Exposure, Caregiver Depression, and Youth Behavioral Health Among Homeless Families.

Res Soc Work Pract 2015 Sep 14;25(5):587-594. Epub 2014 Oct 14.

Silver School of Social Work, New York University, New York, NY, USA ; Silver School of Social Work, McSilver Institute for Poverty Policy & Research, New York University, New York, NY, USA.

Homelessness affects a large and increasing number of families in the United States, and exposure to violence and other potentially traumatic events is common among homeless families. It is important to understand more about this population and, more specifically, about the relationship between youth mental health and caregiver mental health and trauma exposure among homeless families, in order to better serve the needs of this vulnerable population. The objective of this study is to explore the relationships between caregiver exposure to violence, caregiver depression, and youth depression and behavioral problems among homeless families. Preliminary findings indicate that among this sample of homeless families, caregiver violence exposure has statistically significant relationships with both youth behavioral problems and youth depression symptoms, as mediated by caregiver depression. These findings indicate that youth behavioral health is associated with caregiver mental health, which, in turn, is associated with caregiver trauma exposure. This highlights the importance of taking into account adult mental health while treating youth externalizing and internalizing behaviors and ensuring that caregivers, too, have access to adequate treatment and supports. Furthermore, this treatment should be trauma informed, given the link between trauma and mental health.
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http://dx.doi.org/10.1177/1049731514553921DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4584155PMC
September 2015

Utility of compact ultrasound in a mass surgical selection program in Africa: experience of a sonologist at the MV Africa Mercy Hospital Ship's screening day.

J Ultrasound Med 2015 Feb;34(2):341-8

Department of Radiology, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire USA (R.D.H.); Geisel School of Medicine, Dartmouth University, Hanover, New Hampshire USA (R.D.H.); and MV Africa Mercy, Pointe Noire, Republic of Congo, West Africa (G.P.).

Compact ultrasound (US) was introduced in an austere setting with no other available imaging for an annual mass surgical screening day. Compact US examinations were performed on 25 patients from more than 7000 potential patients, as deemed possibly useful by the screening surgeons. Of the 20 patients with recorded data, compact US was helpful in 14 of 20 as a decision-making tool, obviating computed tomography for preoperative planning. Compact US was helpful in most cases, saving resources (computed tomography), technologist time, and radiation risk in this select population.
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http://dx.doi.org/10.7863/ultra.34.2.341DOI Listing
February 2015

Bi-directional Exchange: the Cornerstone of Globally Focused Social Work.

Glob Soc Welf 2014 Mar;1(1):1-8

McSilver Professor of Poverty Studies, Silver School of Social Work, Director, McSilver Institute for Poverty Policy & Research, New York University, New York, USA,

Social work holds a unique place relative to other professions in that it prioritizes the elimination of human suffering as its primary goal. The roots of the profession are firmly planted in Western theories, historically and culturally specific perspectives, and knowledge. History has repeatedly demonstrated an association between the arrival of Westerners and the subsequent control of natural resources. Some argue that the development of global social work practice has serious pitfalls, including diverting needed resources away from local contexts and inadvertently spreading western world-views, paradigms and practices. However, the social work profession is uniquely positioned to offer expertise and collaborate with those experiencing the serious consequences of social inequity and the dearth of economic and social resources locally and across the globe. Grounded in anti-oppressive theory, guided by the difficult, yet acute awareness of western privilege and racism, and drawing from social/collective action and collaborative paradigms, a bi-directional exchange and action are detailed as the foundations for globally focused social work. The skills and knowledge base for global social work are essential as populations locally and worldwide are impacted by a global economic system that innately increases serious social inequity. Comprehensive training and preparation for globally focused social work, critical to successful engagement in global practice are outlined.
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http://dx.doi.org/10.1007/s40609-014-0011-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4208070PMC
March 2014

The development and implementation of theory-driven programs capable of addressing poverty-impacted children's health, mental health, and prevention needs: CHAMP and CHAMP+, evidence-informed, family-based interventions to address HIV risk and care.

J Clin Child Adolesc Psychol 2014 ;43(3):428-41

a Department of Psychiatry and Community Medicine , Mount Sinai School of Medicine.

This article describes a program of prevention and intervention research conducted by the CHAMP (Collaborative HIV prevention and Adolescent Mental health Project; McKay & Paikoff, 2007 ) investigative team. CHAMP refers to a set of theory-driven, evidence-informed, collaboratively designed, family-based approaches meant to address the prevention, health, and mental health needs of poverty-impacted African American and Latino urban youth who are either at risk for HIV exposure or perinatally infected and at high risk for reinfection and possible transmission. CHAMP approaches are informed by theoretical frameworks that incorporate an understanding of the critical influences of multilevel contextual factors on youth risk taking and engagement in protective health behaviors. Highly influential theories include the triadic theory of influence, social action theory, and ecological developmental perspectives. CHAMP program delivery strategies were developed via a highly collaborative process drawing upon community-based participatory research methods in order to enhance cultural and contextual sensitivity of program content and format. The development and preliminary outcomes associated with a family-based intervention for a new population, perinatally HIV-infected youth and their adult caregivers, referred to as CHAMP+, is described to illustrate the integration of theory, existing evidence, and intensive input from consumers and healthcare providers.
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http://dx.doi.org/10.1080/15374416.2014.893519DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4215567PMC
August 2014

Assessment of floodplain vulnerability during extreme Mississippi River flood 2011.

Environ Sci Technol 2014 17;48(5):2619-25. Epub 2014 Feb 17.

Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign , 205 North Mathews Avenue , Urbana, Illinois 61801-2352.

Regional change in the variability and magnitude of flooding could be a major consequence of future global climate change. Extreme floods have the capacity to rapidly transform landscapes and expose landscape vulnerabilities through highly variable spatial patterns of inundation, erosion, and deposition. We use the historic activation of the Birds Point-New Madrid Floodway during the Mississippi and Ohio River Flooding of 2011 as a scientifically unique stress experiment to analyze indicators of floodplain vulnerability. We use pre- and postflood airborne Light Detection and Ranging data sets to locate erosional and depositional hotspots over the 540 km(2) agricultural Floodway. While riparian vegetation between the river and the main levee breach likely prevented widespread deposition, localized scour and deposition occurred near the levee breaches. Eroded gullies nearly 1 km in length were observed at a low ridge of a relict meander scar of the Mississippi River. Our flow modeling and spatial mapping analysis attributes this vulnerability to a combination of erodible soils, flow acceleration associated with legacy fluvial landforms, and a lack of woody vegetation to anchor soil and enhance flow resistance. Results from this study could guide future mitigation and adaptation measures in cases of extreme flooding.
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http://dx.doi.org/10.1021/es404760tDOI Listing
October 2015

Use of TissuePatch™ sealant film in the management of chyle leak in major neck surgery.

Br J Oral Maxillofac Surg 2014 Jan 14;52(1):87-9. Epub 2013 Oct 14.

M/V Africa Mercy, Mercy Ships, West Africa.

Chylous fistula is rare, and operation is often required for high output fistulas after serious operations on the neck. TissuePatch™sealant film (Tissuemed Ltd., Leeds, UK) is a useful adjunct to ensure that potential sources of leakage are sealed effectively.
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http://dx.doi.org/10.1016/j.bjoms.2013.09.007DOI Listing
January 2014

Quantification of chemical transport processes from the soil to surface runoff.

J Environ Qual 2013 Jan-Feb;42(1):83-93

There is a good conceptual understanding of the processes that govern chemical transport from the soil to surface runoff, but few studies have actually quantified these processes separately. Thus, we designed a laboratory flow cell and experimental procedures to quantify the chemical transport from soil to runoff water in the following individual processes: (i) convection with a vertical hydraulic gradient, (ii) convection via surface flow or the Bernoulli effect, (iii) diffusion, and (iv) soil loss. We applied different vertical hydraulic gradients by setting the flow cell to generate different seepage or drainage conditions. Our data confirmed the general form of the convection-diffusion equation. However, we now have additional quantitative data that describe the contribution of each individual chemical loading process in different surface runoff and soil hydrological conditions. The results of this study will be useful for enhancing our understanding of different geochemical processes in the surface soil mixing zone.
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http://dx.doi.org/10.2134/jeq2011.0470DOI Listing
April 2016

Risk factors for late-stage HIV disease presentation at initial HIV diagnosis in Durban, South Africa.

PLoS One 2013 28;8(1):e55305. Epub 2013 Jan 28.

Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, United States of America.

Background: After observing persistently low CD4 counts at initial HIV diagnosis in South Africa, we sought to determine risk factors for late-stage HIV disease presentation among adults.

Methods: We surveyed adults prior to HIV testing at four outpatient clinics in Durban from August 2010 to November 2011. All HIV-infected adults were offered CD4 testing, and late-stage HIV disease was defined as a CD4 count <100 cells/mm(3). We used multivariate regression models to determine the effects of sex, emotional health, social support, distance from clinic, employment, perceived barriers to receiving healthcare, and foregoing healthcare to use money for food, clothing, or housing ("competing needs to healthcare") on presentation with late-stage HIV disease.

Results: Among 3,669 adults screened, 830 were enrolled, newly-diagnosed with HIV and obtained a CD4 result. Among those, 279 (33.6%) presented with late-stage HIV disease. In multivariate analyses, participants who lived ≥5 kilometers from the test site [adjusted odds ratio (AOR) 2.8, 95% CI 1.7-4.7], reported competing needs to healthcare (AOR 1.7, 95% CI 1.2-2.4), were male (AOR 1.7, 95% CI 1.2-2.3), worked outside the home (AOR 1.5, 95% CI 1.1-2.1), perceived health service delivery barriers (AOR 1.5, 95% CI 1.1-2.1), and/or had poor emotional health (AOR 1.4, 95% CI 1.0-1.9) had higher odds of late-stage HIV disease presentation.

Conclusions: Independent risk factors for late-stage HIV disease presentation were from diverse domains, including geographic, economic, demographic, social, and psychosocial. These findings can inform various interventions, such as mobile testing or financial assistance, to reduce the risk of presentation with late-stage HIV disease.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0055305PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3557232PMC
July 2013

Effects of a reduced dose of stavudine on the incidence and severity of peripheral neuropathy in HIV-infected adults in South Africa.

Antivir Ther 2012 13;17(4):737-43. Epub 2012 Mar 13.

Division of Infectious Diseases, Weill Cornell Medical College, New York, NY, USA.

Background: Although recent World Health Organization (WHO) guidelines recommend withdrawing stavudine (d4T) from first-line antiretroviral therapy (ART), it remains commonly used in resource-limited settings. In 2006, WHO recommended decreasing the dose of d4T from 40 mg to 30 mg to mitigate toxicities. We compared the incidence and severity of peripheral neuropathy by d4T dose in a retrospective cohort study.

Methods: Patients' charts from an ART-naive population at a rural clinic in KwaZulu-Natal, South Africa, were retrospectively reviewed for signs and symptoms of incident peripheral neuropathy and were graded for severity using the DAIDS scale. Patients enrolled prior to the WHO guideline change were included in the study if they were on d4T 40 mg for ≥6 months. After the guideline change all patients were initiated on d4T 30 mg.

Results: A total of 475 patients were analysed, including 235 in the 40 mg cohort (152.7 person-years [py]) and 240 in the 30 mg cohort (244.7 py). Incidence of peripheral neuropathy was 90.4/100 py (95% CI 75.9, 106.8) in the 40 mg cohort versus 40.5/100 py (95% CI 32.9, 49.3) in the 30 mg group (incidence rate ratio 0.45; P<0.0001). There was no difference in proportion of severe peripheral neuropathy cases (grade 3/4) between the cohorts: 8.3% in the 40 mg group and 8.9% in the 30 mg group (P=1.0). In a multivariate analysis, risk of peripheral neuropathy was associated with increasing age (hazard ratio [HR] 1.65, 95% CI 1.24, 2.19), 40 mg dose (HR 2.1, 95% CI 1.61, 2.74) and concurrent tuberculosis therapy (HR 1.41, 95% CI 1.06, 1.87).

Conclusions: Incidence of peripheral neuropathy in the 40 mg cohort was extremely high and, although lower, the rate in the 30 mg cohort was nonetheless unacceptably high.
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http://dx.doi.org/10.3851/IMP2087DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3662496PMC
September 2012

Assessing attitudinal barriers toward end-of-life care.

Am J Hosp Palliat Care 2012 Sep 28;29(6):438-42. Epub 2011 Dec 28.

Manager of Research Services, Sisters of Mercy Health System, Oklahoma City, OK, USA.

Due to the rapid influx of Palliative care and Hospice services over the last decade, there has been an increase in the number of medical professionals interacting with terminal patients. One of the challenges with this growth becomes how to integrate these services into already busy practices along with providing physicians the education and tools they need to provide quality care. While there is no shortage of articles focusing on the educational needs of physicians related to end of life care, less is known about the level of anxiety physicians feel about interacting with dying patients and their families.
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http://dx.doi.org/10.1177/1049909111429558DOI Listing
September 2012

Thyroid surgery in the UK and on board the Mercy Ships.

Br J Oral Maxillofac Surg 2012 Oct 17;50(7):592-6. Epub 2011 Nov 17.

St Bartholomew's & the Royal London, and Homerton University Hospitals, London, UK.

Diseases of the thyroid are common in the developed and developing world. We retrospectively compared surgical pathologies, types of thyroidectomy, and postoperative complications between 2 case series, one from the Mercy Ships in West Africa with 87 patients, and the other from London in the United Kingdom with 120 patients. In both, the most common operation was hemithyroidectomy, and nodular hyperplasia was the most common disease. The postoperative complication rate of sero-haematoma was comparable with large international series.
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http://dx.doi.org/10.1016/j.bjoms.2011.10.009DOI Listing
October 2012

Large shift in source of fine sediment in the upper Mississippi river.

Environ Sci Technol 2011 Oct 15;45(20):8804-10. Epub 2011 Sep 15.

Department of Watershed Science, Utah State University, Logan, Utah 84332, USA.

Although sediment is a natural constituent of rivers, excess loading to rivers and streams is a leading cause of impairment and biodiversity loss. Remedial actions require identification of the sources and mechanisms of sediment supply. This task is complicated by the scale and complexity of large watersheds as well as changes in climate and land use that alter the drivers of sediment supply. Previous studies in Lake Pepin, a natural lake on the Mississippi River, indicate that sediment supply to the lake has increased 10-fold over the past 150 years. Herein we combine geochemical fingerprinting and a suite of geomorphic change detection techniques with a sediment mass balance for a tributary watershed to demonstrate that, although the sediment loading remains very large, the dominant source of sediment has shifted from agricultural soil erosion to accelerated erosion of stream banks and bluffs, driven by increased river discharge. Such hydrologic amplification of natural erosion processes calls for a new approach to watershed sediment modeling that explicitly accounts for channel and floodplain dynamics that amplify or dampen landscape processes. Further, this finding illustrates a new challenge in remediating nonpoint sediment pollution and indicates that management efforts must expand from soil erosion to factors contributing to increased water runoff.
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http://dx.doi.org/10.1021/es2019109DOI Listing
October 2011