This experimental study describes the mean and turbulent flow structure in the wake of a circular array of cylinders, which is a model for a patch of emergent vegetation. The patch diameter, D, and ...patch density, a (frontal area per volume), are varied. The flow structure is linked to a nondimensional flow blockage parameter, CDaD, which is the ratio of the patch diameter and a drag length scale (CDa)−1. CD is the cylinder drag coefficient. The velocity exiting the patch, Ue, is reduced relative to the upstream velocity, U∞, and Ue/U∞ decreases as flow blockage (CDaD) increases. A predictive model is developed for Ue/U∞. The wake behind the patch contains two peaks in turbulence intensity. The first peak occurs directly behind the patch and is related to turbulence production within the patch at the scale of individual cylinders. The second peak in turbulence intensity occurs at distance Lwdownstream from the patch and is related to the wake‐scale vortices of the von Karman vortex street. The presence of the flowUe in the wake delays the formation of the von Karman vortex street until distance L1 (<Lw) behind the patch. Both L1 and Lw increase as Ue increases and thus as the flow blockage (CDaD) decreases. L1sets the distance behind the patch within which fine‐particle deposition can occur. BeyondLw, turbulence associated with the wake‐scale vortices inhibits deposition.
Key Points
We describe the adjustment of flow near an emergent patch of vegetation
We develop predictions for velocity and length scales in the patch wake
Wake length scales are related to the deposition pattern in the wake
Abstract
The world's river deltas may collapse under the combined effects of rising sea levels, subsidence, and reduced sediment supply. Saving these deltaic environments requires quantifying ...processes driving collapse. In the Mississippi River Delta, rapid land loss offers an important opportunity to test existing theories for marsh collapse. We use Landsat images to examine how pond expansion by edge retreat contributes to land loss over 34 years in the Atchafalaya‐Vermillion, Terrebonne, and Barataria basins of the Mississippi Delta. Tracking the area changes in ponds on the marsh surface, we find a striking consistency between pond expansion direction and the dominant wind direction and show that wind‐generated waves are capable of causing edge erosion. Expansion rate increases rapidly for ponds wider than 300 m in Terrebonne and Barataria basins. From this, we suggest that ponds in Atchafalaya‐Vermillion basin are stable, whereas ponds in Terrebonne and Barataria are unstable.
Key Points
Wind‐driven pond expansion on Mississippi River Delta Plain is leading to land loss
Marine hydrokinetic (MHK) devices hold the promise of expanding renewable energy production by tapping into the power of waves and currents for electricity generation. However, these devices remain ...in the developmental stage, necessitating research to understand their environmental impacts, lower operational costs, and prevent equipment failures. In this study, we investigate various MHK array configurations to gain insights into their effects on wave patterns, water flow, and sediment conditions, considering both short-term and long-term morphodynamic changes under average and extreme conditions in shallow offshore environments. Our objectives encompass understanding the influence of mean and extreme environmental conditions on MHK devices, evaluating their impact on the bathymetry of the ocean floor, and exploring the role of different array configurations in morphodynamic evolution. Our findings, based on modeling these devices as static lumps, reveal that sediment erosion downstream of MHKs increases by 50% after one year of average conditions. When accounting for the absorption of 30% of the energy by MHK devices, downstream sediment deposition surges by almost 125%. Moreover, alterations in MHK arrays, such as spacing, size, and number, result in noticeable changes in sedimentation magnitudes during storm conditions. While long-term mean wave conditions have minimal effects on sedimentation, extreme wave conditions, akin to large storm events, bring about significant alterations in ocean floor bathymetry, potentially leading to costly maintenance of the MHK arrays. Our research provides a valuable framework for site analysis, enabling the estimation of maintenance needs and the optimization of array configurations to minimize sedimentation-related issues.
The Mississippi Delta in coastal Louisiana has some of the highest rates of land loss in the world. This land-loss crisis might become a global problem because most major deltas are expected to be ...vulnerable to land loss during the remainder of the 21st century and beyond. Despite this predicament, we do not understand how land loss in a deltaic environment proceeds in time and space. Here, we evaluate the spatial and temporal trends of land loss in the Lower Mississippi River Delta (LMRD) region using spatial statistics and landscape metrics. We used nearly 4800 Landsat images to construct a series of three-year cloud-free composites from 1983 to 2016. From these data, we created a stability index (SI), which is a dimensionless measure of the number of land-to-water transitions that a land pixel makes before being considered lost. Our results indicate that on the LMRD, 75% of land loss is a single transition from land to water, while about 25% of land pixels have two or more transitions before being considered lost. Using a local indicator of spatial association, we show that pixels with similar SI tend to cluster together. Single transition clusters (low SI) form elongated shapes, they are densely packed, and they are predominantly, but not always, found on marsh edges. On the other hand, multi-transition clusters (high SI) form square-like shapes, they are more fragmented, and they are usually found in marsh interiors. Our analysis further shows that the land-loss area within the spatial patches with both high and low stability is strongly related to the density of land patches and their shape (R2 of 0.717 and 0.545 respectively). Our analysis suggests that land-loss pixels on the marsh edges undergo different temporal patterns of land loss compared to those in the marsh interior. We hypothesize that this arises because wave edge-erosion drives land loss on marsh edges, whereas subsidence-related flooding drives land loss in marsh interiors. The stability index provides a useful way to characterize the processes causing land loss.
•We define two types of landloss in the Mississippi Delta.•Single transition loss occurs when land converts to water•Multiple transition loss occurs when land converts to water multiple times.•75% of land loss is single transition, the rest undergo multiple transition•These transition types have different shapes and occur in different locations
CAR-T-cell therapy against MM currently shows promising results, but usually with serious toxicities. CAR-NK cells may exert less toxicity when redirected against resistant myeloma cells. CARs can be ...designed through the use of receptors, such as NKG2D, which recognizes a wide range of ligands to provide broad target specificity. Here, we test this approach by analyzing the antitumor activity of activated and expanded NK cells (NKAE) and CD45RA
T cells from MM patients that were engineered to express an NKG2D-based CAR. NKAE cells were cultured with irradiated Clone9.mbIL21 cells. Then, cells were transduced with an NKG2D-4-1BB-CD3z-CAR. CAR-NKAE cells exhibited no evidence of genetic abnormalities. Although memory T cells were more stably transduced, CAR-NKAE cells exhibited greater in vitro cytotoxicity against MM cells, while showing minimal activity against healthy cells. In vivo, CAR-NKAE cells mediated highly efficient abrogation of MM growth, and 25% of the treated mice remained disease free. Overall, these results demonstrate that it is feasible to modify autologous NKAE cells from MM patients to safely express a NKG2D-CAR. Additionally, autologous CAR-NKAE cells display enhanced antimyeloma activity demonstrating that they could be an effective strategy against MM supporting the development of NKG2D-CAR-NK-cell therapy for MM.
The transport of fine sediment and organic matter plays an important role in the nutrient dynamics of shallow aquatic systems, and the fate of these particles is closely linked to vegetation. We ...describe the mean and turbulent flow near circular patches of synthetic vegetation and examine how the spatial distribution of flow is connected to the spatial distribution of suspended sediment deposition. Patches of rigid, emergent, and flexible, submerged vegetation were considered, with two different stem densities. For the rigid emergent vegetation, flow adjustment was primarily two‐dimensional, with flow deflected in the horizontal plane. Horizontal shear layers produced a von Kármán vortex street. Flow through the patch shifted the vortex street downstream, resulting in a region directly downstream of the patch in which both the mean and turbulent velocities were diminished. Net deposition was enhanced within this region. In contrast, for the flexible, submerged vegetation, flow adjustment was three‐dimensional, with shear layers formed in the vertical and horizontal planes. Because of strong vertical circulation, turbulent kinetic energy was elevated directly downstream of the patch. Consistent with this, deposition was not enhanced at any point in the wake. This comparison suggests that morphological feedbacks differ between submerged and emergent vegetation. Further, enhanced deposition occurred only in regions where both turbulent and mean velocities were reduced, relative to the open channel. Reduced deposition (indicating enhanced resuspension) occurred in regions of high turbulence kinetic energy, regardless of local mean velocity. These observations highlight the importance of turbulence in controlling deposition.
Key Points
Comparison of emergent and submerged vegetation impact on flow and deposition
Enhanced deposition observed for emergent patch but not for submerged patch
Enhanced deposition correlated with both low turbulence and low velocity
Abstract
Background
The objective was to estimate the prevalence of household food insecurity (HFI) depending on sociodemographic factors and its association with lifestyle habits and childhood ...overweight and obesity.
Methods
Data was collected from 1,938 children aged 2 to 14 years who participated in the “Study about Malnutrition” of the Community of Madrid. Weight and height were obtained through physical examination. Body mass index was calculated as weight/height
2
(kg/m
2
) and the criteria of the WHO were used for determining conditions of overweight and obesity. The participants’ parents answered a structured questionnaire about their diet, lifestyle (physical activity and screen time), and food insecurity. The diet quality was assessed with the Healthy Eating Index in Spain and food insecurity, defined as the lack of consistent access to sufficient food for a healthy life, was measured via three screening questions and the Household Food Insecurity Access Scale (HFIAS). Odds Ratios (ORs) and Relative Risk Ratios (RRRs) were estimated using logistic regression models and adjusted for confounding variables.
Results
The overall prevalence of HFI was 7.7% (95% CI: 6.6‒9.0), with lower values in children 2 to 4 years old (5.7%, 95% CI: 4.0‒8.1) and significantly higher values in households with low family purchasing power 37.3%; OR: 8.99 (95% CI: 5.5‒14.6). A higher prevalence of overweight (33.1%) and obesity (28.4%) was observed in children from families with HFI, who presented a lower quality diet and longer screen time compared to those from food-secure households (21.0% and 11.5%, respectively). The RRR of children in families with HFI relative to those from food-secure households was 2.41 (95% CI: 1.5‒4.0) for overweight and 1.99 (95% CI: 1.2‒3.4) for obesity.
Conclusion
The prevalence of HFI was high in the paediatric population, especially in households with low family purchasing power. HFI was associated with lower diet quality and higher prevalence of childhood overweight and obesity. Our results suggest the need for paediatric services to detect at-risk households at an early stage to avoid this dual burden of child malnutrition.
The main objective of this research is to analyze the most relevant aspects of the management of the organic fraction of municipal solid waste (OFMSW) and the Sustainable and Circular Production ...Models (SCPMs) in Latin America and the Caribbean (LAC). The bibliometric method was used for the analysis of 190 studies obtained from the Scopus and Latin America and The Caribbean on Health Sciences (LILACS) databases. The systematic review provided information on the main research approaches: identification and characterization; quantification; strategic and interdisciplinary management; and processes for treatment or valorization. Finally, an evaluation of public policies and strategies was performed. The results show that Brazil, Mexico, and Colombia have the highest number of publications on OFMSW. The findings also indicate that both research and policy strategies on SCPMs prioritize bioenergy and biofuels as the leading alternatives for the valorization of OFMSW. It also reflects the relevance of the Circular Economy (CE) and Bioeconomy (BE) as the main drivers of waste recovery and/or valorization in LAC. These aspects are of great interest to governments that are still in the process of implementing SCPMs. However, for those more advanced in this area, it provides valuable information on progress, policy effectiveness, and future actions for improvement.
To design the foundation system of waterway bridges, Load and Resistance Factor Design guidelines suggest use of deterministic scour depth prediction models. Understanding the inherent bias of ...deterministic scour depth prediction models will advance the development of reliability index-based foundation design regime. Four bridge scour depth prediction models were assessed in terms of two statistical parameters, termed herein mean absolute percentage error (MAPE), and conservatism, percentage of cases the predicted scour depth exceeded the measured scour depth. Live-bed laboratory and field scour depth databases were used in analyses to quantify model scatter by comparatively assessing the computed scour depth versus measured data. For live-bed laboratory data, values of MAPE ranged from 23.5% to 59.8%, whereas conservatism ranged from 28.4% to 97.8%. For live-bed field data, conservatism varied from 93.3% to 95.1%, while MAPE ranged from 205.6% to 319%. Statistical models were applied to ascertain the biasness of the four deterministic models. Accuracy and conservatism of a given model were consequently adjusted through proposed modification factors. The proposed approach allows for the selection of a suitable modification factor to satisfy a target probability of deceedance or a target conservatism.
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