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Riverbeds often fine downstream, with a gravel‐bedded reach, a relatively abrupt gravel‐sand transition (GST), and a sand‐bedded reach. Underlying this behavior, bed grain size distributions are often bimodal, with a relative paucity (gap) around the range 1–5 mm. There is no general morphodynamic model capable of producing the grain size gap and gravel‐sand transition autogenically from a unimodal sediment supply. Here we use a one‐dimensional morphodynamic model including size‐specific bedload and suspended load transport, to show that bimodality readily evolves autogenically even under unimodal sediment feed. A GST forms when we include a floodplain width that abruptly increases at some point. Upstream of the transition, non‐gap gravel ceases to move and gap sediment is preferentially transported. At the transition, non‐gap sand rapidly deposits from suspension, enhancing gap sediment mobility and diluting its presence on the bed. Plain Language Summary: The bed surface layer of many rivers is a mixture of sand and gravel. This mixture is described by the probability distribution of grain sizes, and in particular by the median size. Consider the long profile of such a river. Surface median size commonly becomes finer downstream, but often changes abruptly from a value above 5 mm to a value below 1 mm over a short reach. The range 1–5 mm is termed "gap sediment." Here we explain how this abrupt change evolves, even when there is no deficit of gap sediment supplied to the reach, and even though particle abrasion is not included. The grain size distribution autogenically develops two peaks, one in the sand range and one in the gravel range above 5 mm. When abrupt floodplain widening is included, the gravel peak is stronger in the upper reach and the sand peak is stronger in the lower reach, leading to a relatively abrupt gravel‐sand transition. Gap sediment can be diluted both upstream and downstream by a combination of effects due to bedload and suspended load, so that it dominates nowhere in the grain size distribution. Key Points: Numerical simulations show that bed bimodality evolves autogenically, even with unimodal sediment feed and no abrasionAbrupt floodplain widening can lead to the formation of a distinct gravel‐sand transitionThe behavior can be explained by preferential mobility of 1–5 mm sediment over a sand bed combined with fallout of sand from suspension [ABSTRACT FROM AUTHOR]

Abstract: Floodplains and terraces in river valleys play important roles in the transport dynamics of water and sediment. While flat areas in river valleys can be identified from LiDAR data, directly characterizing them as either floodplain or terraces is not yet possible. To address this challenge, we hypothesize that, since geomorphic features are strongly coupled to hydrological and hydraulic dynamics and their associated variability, there exists a return frequency, or possibly a narrow band of return frequencies, of flow that is associated with floodplain formation; and this association can provide a distinctive signature for distinguishing them from terraces. Based on this hypothesis we develop a novel approach for distinguishing between floodplains and terraces that involves transforming the transverse cross‐sectional geometry of a river valley into a curve, named a river valley hypsometric (RVH) curve, and linking hydraulic inundation frequency with the features of this curve. Our approach establishes that the demarcation between floodplains and terraces can be established from the structure of steps and risers in the RVH curves which can be obtained from the DEM data. Further, it shows that these transitions may themselves be shaped by floods with 10‐ to 100‐year recurrence. We additionally show that, when floodplain width and height (above channel bottom) are normalized by bankfull width and depth, the ratio lies in a narrow range independent of the scale of the river valley. Copyright © 2017 John Wiley & Sons, Ltd.

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. [phrase omitted] [phrase omitted] Objectif Evaluer le developpement et la mise en reuvre des directives de pratique clinique pour la gestion de la depression dans le monde. Methodes Nous avons effectue une revue systematique des directives existantes en matiere de gestion de la depression chez les adultes souffrant de troubles depressifs majeurs ou de troubles bipolaires. Pour chaque directive identifiee, nous avons verifie le degre de conformite vis-a-vis des mesures de qualite du developpement des directives (transparence des processus d'elaboration des directives et de leur financement, composition multidisciplinaire du groupe d'auteurs, revue systematique des etudes d'efficacite comparative) ainsi que de la mise en reuvre (indicateurs de qualite). Nous avons confronte les directives des pays a faible et moyen revenu avec celles des pays a haut revenu. Resultats Nous avons identifie 82 directives de pratique clinique nationales et 13 directives de pratique clinique internationales dans 83 pays et en 27 langues. Les processus d'elaboration des directives et les sources de financement etaient explicitement indiquees dans une moindre proportion chez les pays a faible et moyen revenu (8/29; 28%) par rapport aux pays a haut revenu (35/58; 60%). Le nombre de directives redigees par un groupe d'auteurs multidisciplinaire etait moins eleve dans les pays a faible et moyen revenu (2/29; 7%) que dans les pays a haut revenu (22/58; 38%). Une revue systematique de l'efficacite comparative a ete menee pour 31% (9/29) des directives dans les pays a faible et moyen revenu, contre 71% (41/58) des directives dans les pays a haut revenu. Seulement 10% (3/29) des directives emises par les pays a faible et moyen revenu et 19% (11/58) de celles emises par les pays a haut revenu comprenaient un programme d'evaluation des indicateurs de qualite ou de l'adherence aux recommandations. Conclusion La mise en reuvre des directives est mal planifiee, mal analysee et mal mesuree. Reduire les disparites de developpement et de mise en reuvre des directives dans les pays a faible et moyen revenu est une priorite. A l'avenir, ces directives devraient prevoir des strategies d'execution des recommandations, mais aussi d'evaluation de la faisabilite, de la rentabilite et de l'impact sur l'etat de sante. [phrase omitted] Objetivo Evaluar la elaboracion e implementacion de las directrices de practica clinica para el tratamiento de la depresion a nivel mundial. Metodos Se realizo una revision sistematica de las directrices existentes para el tratamiento de la depresion en adultos con trastorno depresivo mayor o bipolar. Por cada directriz identificada, se evaluo el cumplimiento de las medidas de calidad de elaboracion de directrices (como la transparencia en los procesos de elaboracion de directrices y su financiamiento, la composicion del grupo multidisciplinario de autores, la revision sistematica del estudio de eficacia comparativo) y la implementacion (como los indicadores de calidad). En este contexto, se compararon las directrices de los paises de ingresos bajos y medios con las de los paises de ingresos altos. Resultados Se identificaron las directrices de practica clinica a nivel nacional (82) y a nivel internacional (13) de 83 paises en 27 idiomas. Los procesos de elaboracion de directrices y las fuentes de financiamiento se especificaron de manera explicita en un porcentaje menor de directrices de los paises de ingresos bajos y medios (8/29; 28 %) en relacion con las de los paises de ingresos altos (35/58; 60 %). Un grupo de desarrollo multidisciplinario elaboro menos directrices (2/29; 7 %) para los paises de ingresos bajos y medios, en relacion con las de los paises de ingresos altos (22/58; 38 %). Ademas, se realizo una revision sistematica sobre la efectividad comparativa en el 31 % (9/29) de las directrices de los paises de ingresos bajos y medios, frente al 71 % (41/58) de las directrices de los paises de ingresos altos. Solo el 10 % (3/29) de las directrices de los paises de ingresos bajos y medios y el 19 % (11/58) de las directrices de los paises de ingresos altos describieron planes para evaluar los indicadores de calidad o el cumplimiento de las recomendaciones. Conclusion La implementacion de las directrices no se planifica, notifica ni evalua de manera adecuada a nivel mundial. Es prioritario reducir las desigualdades en la elaboracion y la implementacion de las directrices en los paises de ingresos bajos y medios. Las directrices que se elaboren en el futuro deberan presentar estrategias para implementar las recomendaciones y evaluar la viabilidad, la rentabilidad y el impacto en los resultados sanitarios., Introduction The rising prevalence and burden of depression worldwide disproportionately affect low- and middle-income countries. (1-4) Major depressive and bipolar disorders independently increase the risk for other chronic diseases, including [...]

The grain size 2 mm is the conventional border between sand and gravel. This size is used extensively, and generally without much physical justification, to discriminate between such features as sedimentary deposit type (clast-supported versus matrix-supported), river type (gravel bed versus sand bed), and sediment transport relation (gravel versus sand). Here we inquire as to whether this 2 mm boundary is simply a social construct upon which the research community has decided to agree or whether there is some underlying physics. We use dimensionless arguments to show the following for typical conditions on Earth, i.e., natural clasts (e.g., granitic or limestone) in 20 ∘ C water. As grain size ranges from 1 to 5 mm (a narrow band including 2 mm), sediment suspension becomes vanishingly small at normal flood conditions in alluvial rivers. We refer to this range as pea gravel. We further show that bedload movement of a clast in the pea gravel range with, for example, a size of 4 mm moving over a bed of 0.4 mm particles has an enhanced relative mobility compared to a clast with a size of 40 mm moving over a bed of the same 4 mm particles. With this in mind, we use 2 mm here as shorthand for the narrow pea gravel range of 1–5 mm over which transport behavior is distinct from both coarser and finer material. The use of viscosity allows the delineation of a generalized dimensionless bed grain size discriminator between "sand-like" and "gravel-like" rivers. The discriminator is applicable to sediment transport on Titan (ice clasts in flowing methane/ethane liquid at reduced gravity) and Mars (mafic clasts in flowing water at reduced gravity), as well as Earth. [ABSTRACT FROM AUTHOR]

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.