Reconstructing river flows remotely on Earth, Titan, and Mars.

Alluvial rivers are conveyor belts of fluid and sediment that provide a record of upstream climate and erosion on Earth, Titan, and Mars. However, many of Earth's rivers remain unsurveyed, Titan's rivers are not well resolved by current spacecraft data, and Mars' rivers are no longer active, hindering reconstructions of planetary surface conditions. To overcome these problems, we use dimensionless hydraulic geometry relations-scaling laws that relate river channel dimensions to flow and sediment transport rates-to calculate in-channel conditions using only remote sensing measurements of channel width and slope. On Earth, this offers a way to predict flow and sediment flux in rivers that lack field measurements and shows that the distinct dynamics of bedload-dominated, suspended load-dominated, and bedrock rivers give rise to distinct channel characteristics. On Mars, this approach not only predicts grain sizes at Gale Crater and Jezero Crater that overlap with those measured by the Curiosity and Perseverance rovers, it enables reconstructions of past flow conditions that are consistent with proposed long-lived hydrologic activity at both craters. On Titan, our predicted sediment fluxes to the coast of Ontario Lacus could build the lake's river delta in as little as ~1,000 y, and our scaling relationships suggest that Titan's rivers may be wider, slope more gently, and transport sediment at lower flows than rivers on Earth or Mars. Our approach provides a template for predicting channel properties remotely for alluvial rivers across Earth, along with interpreting spacecraft observations of rivers on Titan and Mars.

Poyang and Dongting Lakes, Yangtze River: tributary lakes blocked by main-stem aggradation.

During its 6,300-km course from the Tibetan Plateau to the ocean, the Yangtze River is joined by two large lakes: Dongting Lake and Poyang Lake. We explain why these lakes exist. Deglaciation forced the ocean adjacent to the Yangtze mouth to rise ∼120 m. This forced a wave of rising water surface elevation and concomitant bed aggradation upstream. While aggradation attenuated upstream, the low bed slope of the Middle-Lower Yangtze River (∼2 × 10-5 near Wuhan) made it susceptible to sea level rise. The main stem, sourced at 5,054 m above sea level, had a substantial sediment load to "fight" against water surface level rise by means of bed aggradation. The tributaries of the Middle-Lower Yangtze have reliefs of approximately hundreds of meters, and did not have enough sediment supply to fill the tributary accommodation space created by main-stem aggradation. We show that the resulting tributary blockage likely gave rise to the lakes. We justify this using field data and numerical modeling, and derive a dimensionless number capturing the critical rate of water surface rise for blockage versus nonblockage.

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

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.

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

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.

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

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.

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

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.

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

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.

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

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.

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

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.

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

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.

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

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.

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.

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.

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

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.

Assessment of floodplain vulnerability during extreme Mississippi River flood 2011.

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.

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.

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.

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

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.

The Africa Temporal Scalp Flap: A Novel Flap for Facial Reconstruction.

Although a number of flaps exist for nasal reconstruction, severe scarring of the forehead after burn injury led to the development of a novel two-stage flap based on the superficial temporal artery. The Africa Temporal Scalp (ATS) flap is composed of an axial ascending part on the superficial temporal artery, and a descending anterior extension for reconstruction of the midface. This is a retrospective analysis of all patients who underwent ATS flap surgery on the MV Africa Mercy. During the 7.5-year period, the ATS flap was applied to 45 facial reconstructions, with a median age of 28 years (range 19 months to 51 years). The main indications were previous burn injury (n = 27, 60%) and noma (n = 15, 33.3%). The majority of the flaps were used to reconstruct the lower third of the nose (n = 39, 86.7%), and the remaining six were for the lips or cheek. Experience allowed for earlier division than 3 weeks depending on the length of the flap, and the recipient site. There was one partial flap loss, one infection requiring revision, and two injuries to frontal branch of the facial nerve. The ATS flap is a novel two-stage flap that has proved especially versatile when forehead flaps are unavailable for nasal reconstruction due to extensive forehead scarring. The ATS flap reliably provides ample supple skin, and the donor site is effectively obscured from view, located in the periphery of the face.

The influence of riparian woody vegetation on bankfull alluvial river morphodynamics.

Exploring the effects of bank vegetation on fluvial morphodynamics has long been an essential part of fluvial morphodynamic-related research. In a practical sense, a central question is: does increased vegetation density increase or decrease the channel width? Several aspects concerning the role of vegetation may result in examples of both width decrease and increase. In this study, we examined more than 170 alluvial river sections. Our goal was to detect the phenomena that ultimately determine riparian woody vegetation-induced width variation. We found that bed material is a governing factor. In the case of fine-grained material, i.e. median size D50 < 2 mm, increasingly densely forested riparian vegetation reduces the bankfull Shields number, and destabilizes the banks toward a wider bankfull channel. In the case of coarse-grained material (i.e. median size D50 ≥ 16 mm), the effect is the opposite; increased density is correlated with a higher bankfull Shields number and a narrower bankfull channel. The extent of the role of vegetation varies depending on the ratio of characteristic root zone depth to channel depth and channel width. We present an improved estimator for bankfull Shields number, which considers riparian vegetation density. The bankfull Shields number can be estimated up to 19% more accurately with our corrected estimator.

Global Surgery and Mercy Ships.

Two-thirds of the world population do not have access to safe, affordable and timely surgery. This global surgical crisis largely affects low and middle-income countries, and it will surpass the challenges created by communicable diseases. The barriers of access to surgery range from cost of surgery and patient transportation to availability and quality of surgical infrastructure and providers. Mercy Ships is a Non-Governmental Organisation (NGO) providing free world-class life-saving and life-transforming surgery to the poorest of the poor in West Africa. In order to address barriers to access surgical assessment and care, Mercy Ships switched from centralised patient selection mainly in port cities or capitals to decentralised selection strategy staffed by experienced nursing teams travelling to remote locations nearer to patients' homes. In this way, the under-served rural population is given equal opportunity to access Mercy Ships' free specialised surgical services. In each country served by the Mercy Ships, a 5 year country engagement program is created to focus on improving the quality of life for people living with disease, disfigurement and disability through free direct medical service to reduce the burden of unmet surgical needs. Moreover, our Medical Capacity Building teams concentrate in improving infrastructure and quality control, equipment donation and maintenance. Lastly, Mercy Ships partner with government and policy makers to improve and strengthen their local surgical care delivery system as an indispensable part of the healthcare system. In this vast sea of global surgical crisis, the vision of the Mercy Ships is to eradicate the 'disease of poverty' and effectively do itself out of a job. Mercy Ships' new and the world's largest (37,000 ton) purpose-built hospital ship, the Global Mercy, is joining our current ship, the Africa Mercy (16,500 ton) to save lives and to strengthen local surgical care service. This will more than double our capacity and impact in sub-Saharan Africa following COVID-19 pandemic. Moreover our state-of-art on-board simulation laboratories and traditional practical training of local healthcare providers will further enhance and build their medical capacity. The Global Mercy will become the largest floating and training platform to train next generation African medical and health care professionals so that they can save countless lives by training others in the future. We therefore invite you to partner with us in bringing hope and healing to the forgotten poor in West Africa.