Hydrogeomorphology-Ecology Interactions in River Systems

The work included in this special issue was funded by the European Union's FP7 programme under grant agreement no. 282656 (REFORM

Patches in a side-by-side configuration: a description of the flow and deposition fields

In the last few decades, a lot of research attention has been paid to flow-vegetation interactions. Starting with the description of the flow field around uniform macrophyte stands, research has evolved more recently to the description of flow fields around individual, distinct patches. However, in the field, vegetation patches almost never occur in isolation. As such, patches will influence each other during their development and interacting, complex flow fields can be expected. In this study, two emergent patches of the same diameter (D = 22 cm) and a solid volume fraction of 10% were placed in a side-by-side configuration in a lab flume. The patches were built as an array of wooden cylinders, and the distance between the patches (gap width Delta) was varied between Delta = 0 and 14 cm. Flow measurements were performed by a 3D Vectrino Velocimeter (Nortek AS) at mid-depth of the flow. Deposition experiments of suspended solids were performed for selected gap widths. Directly behind each patch, the wake evolved in a manner identical to that of a single, isolated patch. On the centerline between the patches, the maximum velocity U-max was found to be independent of the gap width Delta. However, the length over which this maximum velocity persists, the potential core L-j, increased linearly as the gap width increased. After the merging of the wakes, the centerline velocity reaches a minimum value U-min. The minimum centerline velocity decreased in magnitude as the gap width decreased. The velocity pattern within the wake is reflected in the deposition patterns. An erosion zone occurs on the centerline between the patches, where the velocity is elevated. Deposition occurs in the low velocity zones directly behind each patch and also downstream of the patches, along the centerline between the patches at the point of local velocity minimum. This downstream deposition zone, a result of the interaction of neighbouring patch wakes, may facilitate the establishment of new vegetation, which may eventually inhibit flow between the upstream patches and facilitate patch merger

Vegetation-Hydrogeomorphology Interactions in a Low-Energy, Human-Impacted River

The work leading to this paper received funding from the European Union's FP7 programme under grant agreement no. 282656 (REFORM)

‘Striking the Right Balance’ in Targeting PPARγ in the Metabolic Syndrome: Novel Insights from Human Genetic Studies

At a time when the twin epidemics of obesity and type 2 diabetes threaten to engulf even the most well-resourced Western healthcare systems, the nuclear receptor peroxisome proliferator-activated receptor γ (PPARγ) has emerged as a bona fide therapeutic target for treating human metabolic disease. The novel insulin-sensitizing antidiabetic thiazolidinediones (TZDs, e.g., rosiglitazone, pioglitazone), which are licensed for use in the treatment of type 2 diabetes, are high-affinity PPARγ ligands, whose beneficial effects extend beyond improvement in glycaemic control to include amelioration of dyslipidaemia, lowering of blood pressure, and favourable modulation of macrophage lipid handling and inflammatory responses. However, a major drawback to the clinical use of exisiting TZDs is weight gain, reflecting both enhanced adipogenesis and fluid retention, neither of which is desirable in a population that is already overweight and prone to cardiovascular disease. Accordingly, the “search is on” to identify the next generation of PPARγ modulators that will promote maximal clinical benefit by targeting specific facets of the metabolic syndrome (glucose intolerance/diabetes, dyslipidaemia, and hypertension), while simultaneously avoiding undesirable side effects of PPARγ activation (e.g., weight gain). This paper outlines the important clinical and laboratory observations made in human subjects harboring genetic variations in PPARγ that support such a therapeutic strategy

A journal for the modern era.

We live in a time of “now,” when we can pretty much find anything we need at the click of a button, have it delivered to our door within hours, and often without the need to compromise on quality. The market place is more competitive than ever – as a supplier, if you can’t deliver a quality product in a timely manner, then somebody else will step into the gap and, before you know it, the opportunity has closed

The PlaceMarker Survey: A Place-Based Tool for Supporting the Monitoring and Appraisal of River-Related Projects and Natural Capital Assessments

The PlaceMarker Survey is an operational tool to support the delivery of the core aims of England’s Environment Agency (EA) in helping to increase resilience to climate change, manage flood risk, and create a better place for people and wildlife. It was developed in response to a recognised need by the EA’s National Environmental Assessment and Sustainability (NEAS) team for a broad-based survey undertaken in the field to get to know the site and prior to more specialist surveys. The key aim of the survey is to capture in a systematic and consistent way the character and condition of a place where river-related projects such as flood risk management and river restoration schemes are proposed to inform discussions around the design and planning of a project and provide the baseline for future place-based monitoring. The tool comprises: a Study Area Survey and one or more River Surveys, which provide measurements to generate metrics and information to support assessments of Habitat and Biodiversity, Landscape, Amenity, and Heritage. Data are stored, analysed, retrieved, shared, and displayed through a web-based information system. It is intended that a PlaceMarker Survey will be conducted on at least three occasions in the lifetime of a project or asset: pre-inception of a project to understand the broad environmental baseline and assist in the design of a scheme; immediately post-project to confirm the “as-built condition”; and post-recovery from the works to monitor the environmental response to interventions at the site. Tracking the assessments over time informs evaluations of environmental enhancements and supports decision-making around adaptive management

Cardiovascular Disease and Sleep-Disordered Breathing in Acromegaly

Treatment goals in acromegaly include symptom relief, tumour control and reversal of the excess morbidity and mortality associated with the disorder. Cardiovascular complications include concentric biventricular hypertrophy and cardiomyopathy, hypertension, valvular heart disease and arrhythmias, while metabolic disturbance (insulin resistance/diabetes mellitus, dyslipidaemia) further increases the risk of cardiovascular and cerebrovascular events. Sleep-disordered breathing (in the form of sleep apnoea) is also common in patients with acromegaly and may exacerbate cardiovascular dysfunction, in addition to contributing to impaired quality of life. Accordingly, and in keeping with evidence that cardiorespiratory complications in acromegaly are not automatically reversed/ameliorated simply through the attainment of 'safe' growth hormone and insulin-like growth factor 1 levels, recent guidelines have emphasised the need not only to achieve stringent biochemical control, but also to identify and independently treat these comorbidities. It is important, therefore, that patients with acromegaly are systematically screened at diagnosis, and periodically thereafter, for the common cardiovascular and respiratory manifestations and that biochemical targets do not become the only treatment goal

Composite suspended sediment particles and flocculation in glacial meltwaters: preliminary evidence from Alpine and Himalayan basins

Research over the last decade has shown that the suspended sediment loads of many rivers are dominated by composite particles. These particles are also known as aggregates or flocs, and are commonly made up of constituent mineral particles, which evidence a wide range of grain sizes, and organic matter. The resulting in situ or effective particle size characteristics of fluvial suspended sediment exert a major control on all processes of entrainment, transport and deposition. The significance of composite suspended sediment particles in glacial meltwater streams has, however, not been established. Existing data on the particle size characteristics of suspended sediment in glacial meltwaters relate to the dispersed mineral fraction (absolute particle size), which, for certain size fractions, may bear little relationship to the effective or in situ distribution. Existing understanding of composite particle formation within freshwater environments would suggest that in-stream flocculation processes do not take place in glacial meltwater systems because of the absence of organic binding agents. However, we report preliminary scanning electron microscopy data for one Alpine and two Himalayan glaciers that show composite particles are present in the suspended sediment load of the meltwater system. The genesis and structure of these composite particles and their constituent grain size characteristics are discussed. We present evidence for the existence of both aggregates, or composite particles whose features are largely inherited from source materials, and flocs, which represent composite particles produced by instream flocculation processes. In the absence of organic materials, the latter may result solely from electrochemical flocculation in the meltwater sediment system. This type of floc formation has not been reported previously in the freshwater fluvial environment. Further work is needed to test the wider significance of these data and to investigate the effective particle size characteristics of suspended sediment associated with high concentration outburst events. Such events make a major contribution to suspended sediment fluxes in meltwater streams and may provide conditions that are conducive to composite particle formation by flocculation

A novel causal mechanism for grey squirrel bark stripping: The Calcium Hypothesis

AbstractGrey squirrels, Sciurus carolinensis, damage trees in the UK by stripping bark and eating the underlying phloem; squirrel motivation for damage is, however, unknown. Damage can result in deterioration of timber quality and a significant economic toll on the forestry industry. Prediction of severe damage followed by targeted killing of squirrels is the current recommended management option. However, the use of warfarin (an anticoagulant poison) is now restricted in the UK and other more humane methods of killing are labour-intensive, so an alternative solution is needed. A better understanding of what motivates grey squirrels to strip bark may enable a preventive approach to be developed. Whilst the bark stripping literature has explored predictive factors affecting the likelihood of damage, causal understanding is lacking. The aim of this review is to introduce the Calcium Hypothesis as a possible explanation for bark stripping, with a view to informing the prevention of damage. The Calcium Hypothesis states that grey squirrels damage trees to ameliorate a calcium deficiency. The main predictive factors of bark stripping behaviour each inform and lend support to the Calcium Hypothesis. Calcium is stored in tree phloem, and damage increases with phloem width, providing squirrels with more calcium per unit area ingested. Calcium levels increase in trees as active growth resumes after winter dormancy, this occurs immediately prior to the main bark stripping season of May–July, and trees growing most vigorously are at increased risk of damage. It is likely grey squirrels also have a requirement for calcium during the bark stripping season. Adult females will be under post-parturition pressures such as lactation, and juveniles will be going through their main period of bone growth, both of which likely represent a requirement for calcium – which supports an observed positive correlation between juvenile abundance and bark stripping. A high autumnal seed crop increases juvenile recruitment the following spring, and could also induce a requirement for calcium to a population due to the high phosphorus to calcium ratio of seeds. To further investigate the hypothesis, the extent to which grey squirrels can utilise calcium oxalate, as calcium occurs in bark, should be determined, and also the extent to which grey squirrels undergo seasonal periods of calcium deficiency. Increasing our causal understanding of bark stripping could inform the future development of preventive measures to aid forest management