Summary Background Surgical resection is regarded as the only curative option for resectable oesophageal cancer, but pulmonary complications occurring in more than half of patients after open ...oesophagectomy are a great concern. We assessed whether minimally invasive oesophagectomy reduces morbidity compared with open oesophagectomy. Methods We did a multicentre, open-label, randomised controlled trial at five study centres in three countries between June 1, 2009, and March 31, 2011. Patients aged 18–75 years with resectable cancer of the oesophagus or gastro-oesophageal junction were randomly assigned via a computer-generated randomisation sequence to receive either open transthoracic or minimally invasive transthoracic oesophagectomy. Randomisation was stratified by centre. Patients, and investigators undertaking interventions, assessing outcomes, and analysing data, were not masked to group assignment. The primary outcome was pulmonary infection within the first 2 weeks after surgery and during the whole stay in hospital. Analysis was by intention to treat. This trial is registered with the Netherlands Trial Register, NTR TC 2452. Findings We randomly assigned 56 patients to the open oesophagectomy group and 59 to the minimally invasive oesophagectomy group. 16 (29%) patients in the open oesophagectomy group had pulmonary infection in the first 2 weeks compared with five (9%) in the minimally invasive group (relative risk RR 0·30, 95% CI 0·12–0·76; p=0·005). 19 (34%) patients in the open oesophagectomy group had pulmonary infection in-hospital compared with seven (12%) in the minimally invasive group (0·35, 0·16–0·78; p=0·005). For in-hospital mortality, one patient in the open oesophagectomy group died from anastomotic leakage and two in the minimally invasive group from aspiration and mediastinitis after anastomotic leakage. Interpretation These findings provide evidence for the short-term benefits of minimally invasive oesophagectomy for patients with resectable oesophageal cancer. Funding Digestive Surgery Foundation of the Unit of Digestive Surgery of the VU University Medical Centre.
Hydraulic roughness is a fundamental property in river research, as it directly affects water levels, flow strength and the associated sediment transport rates. However, quantification of roughness ...is challenging, as it is not directly measurable in the field. In lowland rivers, bedforms are a major source of hydraulic roughness. Decades of research have focused on dunes to allow parameterization of roughness, with relatively little focus on field verification. This study aims to establish the predictive capacity of current roughness predictors, and to identify reasons for the unexplained part of the variance in roughness. We quantified hydraulic roughness based on the Darcy‐Weisbach friction factor (f) calculated from hydraulic field data of a 78 km‐long trajectory of the river Rhine and river Waal in the Netherlands. This is compared to predicted roughness values based on dune geometry, and to the spatial trends in the local topographic leeside angle, both inferred from bathymetric field data. Results from both approaches show the same general trend and magnitude of roughness values (0.019 < f < 0.069). Roughness inferred from dune geometry explains at best 31% of the variance. Efforts to explain the remaining variance from statistics of the local topographic leeside angles, which supposedly control flow separation, were unsuccessful. Unexpectedly, multi‐kilometer depth oscillations explain 34% of the total roughness variations. We suggest that flow divergence associated with depth increase causes energy loss, which is reflected in an elevated hydraulic roughness. Multi‐kilometer depth variations occur in many rivers worldwide, which implies a cause of flow resistance that needs further study.
Plain Language Summary
Hydraulic roughness is the resistance that a river flow experiences from the bed and banks of the channel. Studying hydraulic roughness aids in the prediction of flooding, as increased resistance causes the water level to rise. Previous research on hydraulic roughness has mainly focused on the effect of the shape of river dunes at the river bed. Dunes cause resistance, which has been captured in many equations predicting roughness. In this study, we tested several of those equations capturing dune roughness, and examined alternative sources of flow resistance. A 78 km‐long segment of the river Rhine and river Waal in the Netherlands was used as a case study. Hydraulic roughness was inferred from longitudinal water surface level profiles measured with a survey vessel, and also from river dune dimensions. Both methodologies resulted in similar values and the same general trend of roughness, however, river dune dimensions only explained about one third of the total observed variation. We found that, contrary to expectations, multiple‐kilometer long fluctuations of the river bed elevation influence roughness as well. As the river deepens, the flow weakens, increasing roughness in that region. This is an important finding, since many rivers feature such multi‐kilometer depth variation.
Key Points
Roughness predictions based on bedform geometry explain about 1/3th of the variance in friction factors inferred from water surface profiles
Metrics capturing dune leeside angle statistics do not outperform classical hydraulic roughness predictors in explaining friction variation
Bed‐level gradients oscillate in counter phase with the friction factor, indicating the importance of multi‐kilometer depth variations
Arthropod pest outbreaks are unpredictable and not uniformly distributed within fields. Early outbreak detection and treatment application are inherent to effective pest management, allowing ...management decisions to be implemented before pests are well-established and crop losses accrue. Pest monitoring is time-consuming and may be hampered by lack of reliable or cost-effective sampling techniques. Thus, we argue that an important research challenge associated with enhanced sustainability of pest management in modern agriculture is developing and promoting improved crop monitoring procedures. Biotic stress, such as herbivory by arthropod pests, elicits physiological defense responses in plants, leading to changes in leaf reflectance. Advanced imaging technologies can detect such changes, and can, therefore, be used as noninvasive crop monitoring methods. Furthermore, novel methods of treatment precision application are required. Both sensing and actuation technologies can be mounted on equipment moving through fields (e.g., irrigation equipment), on (un)manned driving vehicles, and on small drones. In this review, we focus specifically on use of small unmanned aerial robots, or small drones, in agricultural systems. Acquired and processed canopy reflectance data obtained with sensing drones could potentially be transmitted as a digital map to guide a second type of drone, actuation drones, to deliver solutions to the identified pest hotspots, such as precision releases of natural enemies and/or precision-sprays of pesticides. We emphasize how sustainable pest management in 21st-century agriculture will depend heavily on novel technologies, and how this trend will lead to a growing need for multi-disciplinary research collaborations between agronomists, ecologists, software programmers, and engineers.
Background
Many studies indicate that smaller life space is related to worse cognitive and motor function. It is plausible that cognitive and motor function also predict life space constriction, thus ...long‐term, prospective studies are needed of cognitive and motor function as predictors of life space.
Methods
A total of 1246 participants of the Rush Memory and Aging Project, who reported initial maximal life space and at least one follow‐up assessment were included in this prospective study, with up to 19 years follow‐up. The outcome of interest was the Modified version of the Life Space Questionnaire; which we categorized into large (beyond community), medium (neighborhood/community), and small (home/yard) life space. Participants also had detailed composite measures of global cognition and motor function as predictors and available at the first life space assessment. Life space transitions over one‐year periods were modeled using multistate Markov modeling, including confounders and both predictors simultaneously.
Results
Better cognitive and motor function were broadly associated with lower odds of life space constriction (Cognitive: Large ➔ medium: OR = 0.91, 95% CI 0.83–1.00; Large ➔ small: OR = 0.85, 95% CI 0.74–0.97; Medium ➔ small: OR = 1.01, 95% CI 0.82–1.22. Motor: large ➔ medium: OR = 0.76, 95% CI 0.69–0.83; large ➔ small: OR = 0.58, 95% CI 0.51–0.67; medium ➔ small: OR = 0.71, 95% CI = 0.57–0.87).
Conclusions
Combined with previous literature that life space predicts function, these results support the notion of complex inter‐relations of cognitive function, motor function, and life space.
Maize (Zea mays ssp. mays) is one of the most important crops worldwide and there are many reports in the literature on its constitutive and inducible defenses against pathogens and insects. However, ...research on its wild ancestors, the teosintes, with respect to resistance against these antagonists is limited. Here, we review what is known about the different arthropods and microbes that are associated with maize and teosintes in Mexico and Central America, the area of origin, and evaluate the plants' mechanisms of resistance against biotic stresses. Teosintes appear to have greater resistance against a number of pests than their cultivated counterpart. We therefore highlight the need to study the teosintes in order to identify resistance traits that can be improved in maize. As teosintes are at risk of becoming extinct, there is a need to protect their germplasm for future generations.
Geometric characteristics of subaqueous bedforms, such as height, length and leeside angle, are crucial for determining hydraulic form roughness and interpreting sedimentary records. Traditionally, ...bedform existence and geometry predictors are primarily based on uniform, cohesionless sediments. However, mixtures of sand, silt and clay are common in deltaic, estuarine, and lowland river environments, where bedforms are ubiquitous. Therefore, we investigate the impact of fine sand and silt in sand‐silt mixtures on bedform geometry, based on laboratory experiments conducted in a recirculating flume. We systematically varied the fraction of sand and silt for different discharges, and utilized an acoustic Doppler velocimeter to measure flow velocity profiles. The final bed geometry was captured using a line laser scanner. Our findings reveal that the response of bedforms to an altered fine sediment percentage is ambiguous, and likely depends on, among others, bimodality‐driven bed mobility and sediment cohesiveness. When fine, non‐cohesive material (fine sand or coarse silt) is mixed with the base material (medium sand), an increased dune height and length is observed, possibly caused by the hiding‐exposure effect, resulting in enhanced mobility of the coarser material. However, weakly cohesive fine silt suppresses dune height and length, possibly caused by reduced sediment mobility. Finally, in the transition from dunes to upper stage plane bed, there are indications that the bed becomes unstable and dune heights vary over time. The composition of the bed material does not significantly impact the hydraulic roughness, but mainly affects roughness via the bed morphology, especially the leeside angle.
Plain Language Summary
Underwater bedforms, such as dunes, are often found on the bed of rivers and deltas. These rhythmic undulations have specific shapes and sizes, and they affect how water flows. When the bed of the river is made up of sand, we can predict the dune height and length. However, mixtures of different‐sized sediments are common in rivers, and it is unknown how this impacts the geometry of the dunes. Therefore, we did experiments in a flume, a laboratory facility to simulate a river, and we tested different sediment bed mixtures. We found that replacing part of the base material with non‐cohesive fine particles leads to longer dunes, likely caused by increased mobility of the base material. However, for weakly cohesive fine particles, the effect was the opposite, and the dunes became shorter, probably due to the limited mobility of the sediment. Finally, we observed that under high flow conditions, the bed became unstable and different dune shapes occurred. We found that the friction the water experiences is not directly impacted by the sediment bed mixtures, but is mostly affected by the shape of the bedforms.
Key Points
An increased dune length due to a larger fraction of finer, non‐cohesive material in a sand bed, implies an increased mobility of the sand
A decreased dune size due to a larger fraction of finer, weakly cohesive silt in a sand bed, implies a decreased mobility of the sand
Sediment bed composition indirectly affects hydraulic roughness by altering bedform geometry
Summary
A considerable proportion of patients with chronic myeloid leukaemia (CML) may present at diagnosis with high platelet counts. This may result in thrombosis or bleeding complications due to ...binding of von Willebrand factor (VWF) multimers to platelets. Paediatric CML is very rare and no systematic investigation on clinical complications of elevated platelets has been reported. Data on platelet count and associated haemostaseological complications were retrospectively analysed in a cohort of 156 children with CML. Fifty‐one percent (81/156) patients presented with thrombocytosis (platelet count> 500 × 109/l), and were extreme (>1 000 × 109/l) in 23/156 (16%). There were no cases of thrombosis but mild bleeding signs were present in 12% (n = 9) children with thrombocytosis. Bleeding occurred without correlation to elevated platelet counts and was associated with reduced large VWF multimers, indicating a diagnosis of acquired von Willebrand syndrome (AVWS), which resolved after initiation of CML treatment. Patients with paediatric CML frequently exhibit high platelet counts not resulting in thrombosis. In patients with thrombocytosis mild bleeding signs due to a low percentage of large VWF multimers can be demonstrated. AVWS may be underdiagnosed in paediatric CML (Clinical‐Trials.gov NCT00445822, 9 March 2007).
Accurate particle size distribution (PSD) measurements of suspended particulate matter (SPM) composed of flocs and aggregates are important to improve understanding of ecological and geomorphological ...processes, and for environmental engineering applications. PSDs can be measured in situ (in the field) using a submersible sensor, or ex situ (in the laboratory) using samples. The methodological choice is often guided by logistical factors, and the differences in PSDs acquired by in situ and ex situ measurements is of concern. In this study, a laser‐diffraction instrument (the LISST‐200X) was used to compare in situ and ex situ PSD measurements. Samples measured ex situ were stored for three consecutive weeks and measured each week in a laboratory using different stirrer speeds. We observed that ex situ measurements display a higher D50 (median particle size) than in situ measurements of the same sample (up to 613% larger, 112% on average). Our experiments show that the difference between in situ and ex situ measurements can be explained by flocculation of the riverine sediments during the first week of storage. During the subsequent ex situ measurements, the stirring results in a significantly lower D50. Ex situ measurements are therefore unsuitable for flocculated SPM. This study provides recommendations for optimizing PSD measurements by calculating the measurement times required to obtain robust PSD measurements (exceeding 3 min per sample), which are larger for field samples with coarser particles and wider PSDs.
Plain Language Summary
Measurements of the size of particles suspended in a water column are important for understanding many processes related to river ecology and morphology. It is possible to measure these particles directly in the field using a submersible sensor (in situ), or by taking samples and transporting them to a laboratory (ex situ). The choice between these options often depends on logistics, with little recognition of the impact that this choice can have on the measurements. In this research, the differences between in situ and ex situ measurements are explored. We find that ex situ measured particle sizes are on average 112% larger than in situ measurements, which can be related to flocculation of the riverine particles. Flocs are a combination of mineral particles (such as silt or clay) and organic particles, forming larger aggregates. Our results show that flocs grow when a sample is taken to the laboratory and stored. During ex situ measurements, which involve stirring, they break apart. Ex situ measurements are therefore unsuitable for determining the natural particle size. We show how long a measurement should last to give a representative particle size. In situ, longer measurement periods are needed.
Key Points
The D50, a generic way to parametrize particle size distributions (PSDs), is not an absolute number, but depends on the measurement method
Differences between in situ and ex situ measured PSDs are caused by the ex situ alteration of flocculated particles
A robust PSD measurement with laser diffraction takes longer for coarser field samples with a wider distribution
Following advice from the World Bank, and hoping for economic growth and independence from donors, a number of African countries have opened up opportunities for large-scale mining by foreign ...investors over the last decade and a half. Tanzania, one of the ' new' mining countries, is now among the largest gold producers in Africa, but investor-friendly contracts have resulted in extremely low government revenues from mining, totalling less than 5 percent of what the country receives in development aid. In response to widespread discontent, and acknowledging the plight of affected communities, the government amended the 1998 Mining Act in 2010. However, improved legal provisions may have limited effect if the present governance challenges are not resolved. The article demonstrates that the legal provisions meant to protect the rights of affected people are not followed, and that poorly functioning local democracy is particularly dangerous for pastoralists who are ' represented' by local authorities often dominated by non-pastoralist immigrants. Compensation to smallholder farmers is either non-existent or too low -or the compensation money is embezzled by the authorities entrusted to distribute it.
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