Modelling diverse root density dynamics and deep nitrogen uptake — a simple approach

We present a 2-D model for simulation of root density and plant nitrogen (N) uptake for crops grown in agricultural systems, based on a modification of the root density equation originally proposed by Gerwitz and Page in J Appl Ecol 11:773–781, (1974). A root system form parameter was introduced to describe the distribution of root length vertically and horizontally in the soil profile. The form parameter can vary from 0 where root density is evenly distributed through the soil profile, to 8 where practically all roots are found near the surface. The root model has other components describing root features, such as specific root length and plant N uptake kinetics. The same approach is used to distribute root length horizontally, allowing simulation of root growth and plant N uptake in row crops. The rooting depth penetration rate and depth distribution of root density were found to be the most important parameters controlling crop N uptake from deeper soil layers. The validity of the root distribution model was tested with field data for white cabbage, red beet, and leek. The model was able to simulate very different root distributions, but it was not able to simulate increasing root density with depth as seen in the experimental results for white cabbage. The model was able to simulate N depletion in different soil layers in two field studies. One included vegetable crops with very different rooting depths and the other compared effects of spring wheat and winter wheat. In both experiments variation in spring soil N availability and depth distribution was varied by the use of cover crops. This shows the model sensitivity to the form parameter value and the ability of the model to reproduce N depletion in soil layers. This work shows that the relatively simple root model developed, driven by degree days and simulated crop growth, can be used to simulate crop soil N uptake and depletion appropriately in low N input crop production systems, with a requirement of few measured parameters

Plant Biomarker Pattern, Apples grown with various availability of organic nitrogen and with or witout the use of pesticides

In the recent years there has been an increasing focus on the quality and health value of organic plant products compared with conventional products. The use of pesticides and concentrated fertilisers in conventional agriculture implies a risk of effects on plant composition, which may affect health of the consumer (Brandt & Mølgaard, 2001). To determine if organically grown plant food could provide more or less benefits to health than conventional food, a first step is to investigate the differences in the composition and relative concentration of natural compounds in the plant products. In this project apples were grown with two levels of nitrogen availability and with or without the use of pesticides. The apples were screened for changes in the phytochemical composition and concentration. The work is affiliated to the project "Organic food and health" supported by the Danish Research Centre for Organic Farming (DARCOF). Biomarkers and biomarker patterns were presented in plants cultivated with low and high N and with pesticides. One biomarker was related to: • the type of N with and without pesticides • pesticides at high N and type of N without pesticides • pesticides at low and high N One biomarker pattern was related to: • the type of N • the type of N without pesticides • pesticides at low N and type of N without pesticides • pesticides at high N and type of N with pesticide

Tissue doppler imaging predicts improved systolic performance and reversed left ventricular remodeling during long-term cardiac resynchronization therapy

AbstractObjectivesWe sought to evaluate the long-term impact of cardiac resynchronization therapy (CRT) on left ventricular (LV) performance and remodeling using three-dimensional echocardiography and tissue Doppler imaging (TDI).BackgroundThree-dimensional echocardiography and TDI allow rapid and accurate evaluation of LV volumes and performance.MethodsTwenty-five consecutive patients with severe heart failure and bundle branch block who underwent biventricular pacemaker implantation were included. Before and after implantation of the pacemaker, three-dimensional echocardiography and TDI were performed. These examinations were repeated at outpatient visits every six months.ResultsFive patients (20%) died during one-year follow-up. In the remaining 20 patients, significant reductions in LV end-diastolic volume and LV end-systolic volume of 9.6 ± 14% and 16.5 ± 15%, respectively (p < 0.01), could be demonstrated during long-term follow-up. Accordingly, LV ejection fraction increased by 21.7 ± 18% (p < 0.01). According to a newly developed TDI technique—tissue tracking—all regional myocardial segments improved their longitudinal systolic shortening (p < 0.01). The extent of the LV base displaying delayed longitudinal contraction, as detected by TDI before pacemaker implantation, predicted long-term efficacy of CRT. The QRS duration failed to predict resynchronization efficacy.ConclusionsCardiac resynchronization significantly improved LV function and reversed LV remodeling during long-term follow-up. Patients likely to benefit from CRT can be identified by TDI before implantation of a biventricular pacemaker

EU-Rotate_N – a decision support system – to predict environmental and economic consequences of the management of nitrogen fertiliser in crop rotations

A model has been developed which assesses the economic and environmental performance of crop rotations, in both conventional and organic cropping, for over 70 arable and horticultural crops, and a wide range of growing conditions in Europe. The model, though originally based on the N_ABLE model, has been completely rewritten and contains new routines to simulate root development, the mineralisation and release of nitrogen (N) from soil organic matter and crop residues, and water dynamics in soil. New routines have been added to estimate the effects of sub-optimal rates of N and spacing on the marketable outputs and gross margins. The model provides a mechanism for generating scenarios to represent a range of differing crop and fertiliser management strategies which can be used to evaluate their effects on yield, gross margin and losses of nitrogen through leaching. Such testing has revealed that nitrogen management can be improved and that there is potential to increase gross margins whilst reducing nitrogen losses

Beacon Signalling for Expedited Cell Search Procedures in NTN NB-IoT

Three cellular standards have been considered for Non-Terrestrial Networks (NTN): NB-IoT, eMTC and NR, each having had features introduced to accommodate the challenges of the NTN case. In Terrestrial Networks (TNs), it is reasonable to expect continuous coverage when a UE is stationary within reach of a base-station (eNB) with rare exceptions of downtime due to failures or catastrophic events. The same continuity cannot be assumed in NTN for sparse eNB constellations or during the rollout of dense eNB constellations. Therefore, a feature of the NTN IoT protocols - NTN NB-IoT & NTN eMTC - is the support of discontinuous RAN coverage. Cell search is a core task of NTN UEs serviced by non-geostationary (NGSO) constellations. Initially, when UEs are booted up, unless a recent ephemeris has been provisioned to it, the UE must first discover a valid eNB by employing repeated cell searching. UEs will have to keep doing cell search each time they wish to access a cell again after losing or dropping connectivity. Intermittent coverage gaps, which occur in dense constellations due to system failures, during rollout or inherently in sparse constellations, exaggerate the number of cell search attempts required by a UE before finding an appropriate cell to camp on. These latter cases of intermittent coverage can be mitigated by the coverage prediction features for discontinuous coverage. In this paper, a beacon signal, which can be transmitted within the white-spaces of stand-alone NB-IoT, is introduced. The beacon signal is designed to expedite the cell search procedure in NTN NB-IoT in NGSO constellations by: (1) Allowing for easy and early detection of the presence of a cell, (2) encoding preliminary information for the UE to assess whether to continue cell search at that early point and (3) providing helpful information to the synchronisation procedure. The performance of the beacon signal is simulated and evaluations show a fair improvement over utilizing legacy synchronization signals for cell detection both in terms of speed and SNR