Opportunities for weed manipulation using GMHT row crops

The herbicides and cultivation systems available in most non-GM crops allow farmers little flexibility as to when they control weeds. However, glyphosate and glufosinate-ammonium, as used in GM herbicide tolerant crops, offer the opportunity to control large weeds and weed control can be timed according to the agronomic and environmental aims of the user. This paper will use sugar beet as a model crop and report results where different approaches to weed control have been used and discuss their relevance in the wider agricultural and environmental contextNon peer reviewe

A ratio model of perceived speed in the human visual system

The perceived speed of moving images changes over time. Prolonged viewing of a pattern (adaptation) leads to an exponential decrease in its perceived speed. Similarly, responses of neurones tuned to motion reduce exponentially over time. It is tempting to link these phenomena. However, under certain conditions, perceived speed increases after adaptation and the time course of these perceptual effects varies widely. We propose a model that comprises two temporally tuned mechanisms whose sensitivities reduce exponentially over time. Perceived speed is taken as the ratio of these filters' outputs. The model captures increases and decreases in perceived speed following adaptation and describes our data well with just four free parameters. Whilst the model captures perceptual time courses that vary widely, parameter estimates for the time constants of the underlying filters are in good agreement with estimates of the time course of adaptation of direction selective neurones in the mammalian visual system

Relaxed multi-marginal costs and quantization effects

We propose a duality theory for multi-marginal repulsive cost that appear in optimal transport problems arising in Density Functional Theory. The related optimization problems involve probabilities on the entire space and, as minimizing sequences may lose mass at infinity, it is natural to expect relaxed solutions which are sub-probabilities. We first characterize the $N$-marginals relaxed cost in terms of a stratification formula which takes into account all $k$ interactions with $kle N$. We then develop a duality framework involving continuous functions vanishing at infinity and deduce primal-dual necessary and sufficient optimality conditions. Next we prove the existence and the regularity of an optimal dual potential under very mild assumptions. In the last part of the paper, we apply our results to a minimization problem involving a given continuous potential and we give evidence of a mass quantization effect for optimal solutions

Dissociating limit in Density Functional Theory with Coulomb optimal transport cost

In the framework of Density Functional Theory with Strongly Correlated Electrons we consider the so called bond dissociating limit for the energy of an aggregate of atoms. We show that the multi-marginals optimal transport cost with Coulombian electron-electron repulsion describes a dissociation effect. The variational limit is completely calculated in the case of $N=2$ electrons. The theme of fractional number of electrons appears naturally and brings into play the question of optimal partial transport cost. A plan is outlined to complete the analysis which involves the study of the relaxation of optimal transport cost with respect to the weak* convergence of measures

Dynamic Compaction of Biomaterial Powders

Dynamic compaction which requires no external heating for consolidation was used to compact hydroxyapatite. Static precompaction of 3 MPa and dynamic compaction using a projectile velocity of 50 m/s resulted in compacts having a compaction degree of 65% and a tensile strength of 12.4 ± 2.7 MPa This strength was very close to that obtained with sintered compacts one and seemed to indicate that some interparticle boundaries had been created during dynamic compaction

Interfacing GHz-bandwidth heralded single photons with a room-temperature Raman quantum memory

Photonics is a promising platform for quantum technologies. However, photon sources and two-photon gates currently only operate probabilistically. Large-scale photonic processing will therefore be impossible without a multiplexing strategy to actively select successful events. High time-bandwidth-product quantum memories - devices that store and retrieve single photons on-demand - provide an efficient remedy via active synchronisation. Here we interface a GHz-bandwidth heralded single-photon source and a room-temperature Raman memory with a time-bandwidth product exceeding 1000. We store heralded single photons and observe a clear influence of the input photon statistics on the retrieved light, which agrees with our theoretical model. The preservation of the stored field's statistics is limited by four-wave-mixing noise, which we identify as the key remaining challenge in the development of practical memories for scalable photonic information processing

Sediment Sorting and Rounding in a Basaltic Glacio-Fluvio-Aeolian Environment: hrisjkull Glacier, Iceland

Sediments and sedimentary rocks preserve a rich history of environment and climate. Identifying these signals requires an understanding of the physical and chemical processes that have affected sedimentary deposits [1]. Such processes include sorting and rounding during transport and chemical alteration through weathering and diagenesis. Although these processes have long been studied in quartz-dominated sedimentary systems [2], a lack of studies of basaltic sedimentary systems limits our interpretations of the environment and climate where mafic source rocks dominate, such as on Mars [3,4]. As part of the SAND-E: Semi-Autonomous Navigation for Detrital Environments project [5], which uses robotic operations to examine physical and chemical changes to sediments in basaltic glacio-fluvialaeolian environments, this research studies changes in sorting and rounding of fluvial-aeolian sediments along a glacier-proximal-to-glacier-distal transect in the outwash-plain of the risjkull glacier in SW Iceland (Fig. 1

Seismic data reveal eastern Black Sea Basin structure

Rifted continental margins are formed by progressive extension of the lithosphere. The development of these margins plays an integral role in the plate tectonic cycle, and an understanding of the extensional process underpins much hydrocarbon exploration. A key issue is whether the lithosphere extends uniformly, or whether extension varies\ud with depth. Crustal extension may be determined using seismic techniques. Lithospheric extension may be inferred from the waterloaded subsidence history, determined from\ud the pattern of sedimentation during and after rifting. Unfortunately, however, many rifted margins are sediment-starved, so the subsidence history is poorly known.\ud To test whether extension varies between the crust and the mantle, a major seismic experiment was conducted in February–March 2005 in the eastern Black Sea Basin (Figure 1), a deep basin where the subsidence history is recorded\ud by a thick, post-rift sedimentary sequence. The seismic data from the experiment indicate the presence of a thick, low-velocity zone, possibly representing overpressured sediments. They also indicate that the basement and\ud Moho in the center of the basin are both several kilometers shallower than previously inferred. These initial observations may have considerable impact on thermal models of the petroleum system in the basin. Understanding\ud the thermal history of potential source rocks is key to reducing hydrocarbon exploration risk. The experiment, which involved collaboration between university groups in the United Kingdom, Ireland, and Turkey, and BP and\ud Turkish Petroleum (TPAO), formed part of a larger project that also is using deep seismic reflection and other geophysical data held by the industry partners to determine the subsidence history and hence the strain evolution of\ud the basin

The impact of routine pulse oximetry use on outcomes in COVID-19-infected patients at increased risk of severe disease: A retrospective cohort analysis

Background. The phenomenon of silent hypoxaemia has been described in patients with COVID-19 pneumonia, which is characterised by low oxygen saturation levels of <90% in those who appear clinically well and do not show signs of significant respiratory distress.Objectives. To assess the impact on clinical outcomes for high-risk COVID-19 patients using a pulse oximeter to monitor oxygen saturation levels in a home setting.Methods. We performed a retrospective cohort analysis using data from a large South African insurance administrator. Patients were categorised as high risk, based on age and specific underlying clinical conditions, or from predictive models derived from medical scheme administrative claims data. The impact of pulse oximetry home monitoring on COVID-19 clinical outcomes was investigated by the use of Cox proportional hazard models.Results. Between 2 March 2020 and 31 October 2020, of 38 660 patients analysed, 8 115 were in the intervention group. The 60-day mortality rate for the evaluated high-risk population was 1.35%. After adjusting for age and comorbidity differences, the intervention group was found to have an adjusted hazard ratio of 0.52 (p<0.0001). No statistical significance was found between the intervened and control groups for admission to hospital, admission to intensive care unit (ICU) and use of mechanical ventilation. The intervention group had a lower median C-reactive protein (CRP) level on admission (p=0.03). After adjustment for admission CRP levels, elevated CRP was associated with an increased mortality (p<0.0001), while the statistical significance in mortality between the intervention and the control group was lost.Conclusions. High-risk COVID-19 patients who used a pulse oximeter to monitor oxygen saturation levels had significantly lower mortality rates compared with other high-risk patients. The mortality benefit may be explained by earlier presentation to hospital, as suggested by lower initial CRP levels.

Convexity criteria and uniqueness of absolutely minimizing functions

We show that absolutely minimizing functions relative to a convex Hamiltonian $H:\mathbb{R}^n \to \mathbb{R}$ are uniquely determined by their boundary values under minimal assumptions on $H.$ Along the way, we extend the known equivalences between comparison with cones, convexity criteria, and absolutely minimizing properties, to this generality. These results perfect a long development in the uniqueness/existence theory of the archetypal problem of the calculus of variations in $L^\infty.$Comment: 34 page