New explicit spike solution -- non-local component of the generalized Mixmaster attractor

By applying a standard solution-generating transformation to an arbitrary vacuum Bianchi type II solution, one generates a new solution with spikes commonly observed in numerical simulations. It is conjectured that the spike solution is part of the generalized Mixmaster attractor.Comment: Significantly revised. Colour figures simplified to accommodate non-colour printin

Contamination

Soil contamination occurs when substances are added to soil, resulting in increases in concentrations above background or reference levels. Pollution may follow from contamination when contaminants are present in amounts that are detrimental to soil quality and become harmful to the environment or human health. Contamination can occur via a range of pathways including direct application to land and indirect application from atmospheric deposition. Contamination was identified by SEPA (2001) as a significant threat to soil quality in many parts of Scotland. Towers et al. (2006) identified four principal contamination threats to Scottish soils: acidification; eutrophication; metals; and pesticides. The Scottish Soil Framework (Scottish Government, 2009) set out the potential impact of these threats on the principal soil functions. Severe contamination can lead to “contaminated land” [as defined under Part IIA of the Environmental Protection Act (1990)]. This report does not consider the state and impacts of contaminated land on the wider environment in detail. For further information on contaminated land, see ‘Dealing with Land Contamination in Scotland’ (SEPA, 2009). This chapter considers the causes of soil contamination and their environmental and socio-economic impacts before going on to discuss the status of, and trends in, levels of contaminants in Scotland’s soils

Coordinate Singularities in Harmonically-sliced Cosmologies

Harmonic slicing has in recent years become a standard way of prescribing the lapse function in numerical simulations of general relativity. However, as was first noticed by Alcubierre (1997), numerical solutions generated using this slicing condition can show pathological behaviour. In this paper, analytic and numerical methods are used to examine harmonic slicings of Kasner and Gowdy cosmological spacetimes. It is shown that in general the slicings are prevented from covering the whole of the spacetimes by the appearance of coordinate singularities. As well as limiting the maximum running times of numerical simulations, the coordinate singularities can lead to features being produced in numerically evolved solutions which must be distinguished from genuine physical effects.Comment: 21 pages, REVTeX, 5 figure

A randomised trial evaluating Bevacizumab as adjuvant therapy following resection of AJCC stage IIB, IIC and III cutaneous melanoma : an update

At present, there are no standard therapies for the adjuvant treatment of malignant melanoma. Patients with primary tumours with a high-Breslow thickness (stages IIB and IIC) or with resected loco-regional nodal disease (stage III) are at high risk of developing metastasis and subsequent disease-related death. Given this, it is important that novel therapies are investigated in the adjuvant melanoma setting. Since angiogenesis is essential for primary tumour growth and the development of metastasis, anti-angiogenic agents are attractive potential therapeutic candidates for clinical trials in the adjuvant setting. Therefore, we initiated a phase II trial in resected high-risk cutaneous melanoma, assessing the efficacy of bevacizumab versus observation. In the interim safety data analysis, we demonstrate that bevacizumab is a safe therapy in the adjuvant melanoma setting with no apparent increase in the surgical complication rate after either primary tumour resection and/or loco-regional lymphadenectomy

Numerical simulations of general gravitational singularities

This paper covers some of the current techniques and issues involved in performing numerical simulations of the formation of singularities.Comment: This work was part of the 2006 AEI conference on New Frontiers in Numerical Relativity and was published in an issue of Classical and Quantum Gravity on that conferenc

Solar and biomass hybridization through hydrothermal carbonization

Hydrothermal carbonization process can transform wet bio-wastes into value-added products. This work aims to hybridize a concentrating solar technology and a biomass reactor for the continuous and sustainable valorization of biomass. The novel technology proposed integrates a linear beam-down solar field with a twin-screw reactor for continuous HTC process. The solar field consists of two reflections that concentrate linearly the sun energy on the ground, where the twin-screw reactor is placed. A mathematical model is proposed to solve both the heat transfer and HTC kinetics for a co-rotating twin-screw reactor. The incoming heat flux from the solar field (8-20 kW/m(2)), the reactor length (L/D = 30-60 where D is the diameter) and the rotating velocity of the screw (25-100 rpm) are the main variables used to process the biomass up to the desired severity factor. The simulation results of different lignocellulosic biomasses (loblolly pine, sugarcane bagasse, corn stover and rice husk) are validated against literature data. The developed model shows good agreement with experimental results shown in the literature. The proposed technology foresees hydrochar yields of 64-78% for severity factors of 4.2 and 5.3, respectively, in agreement to the experimental results of 63-70% shown in literature. (C) 2021 Elsevier Ltd. All rights reserved

Locally U(1)*U(1) Symmetric Cosmological Models: Topology and Dynamics

We show examples which reveal influences of spatial topologies to dynamics, using a class of spatially {\it closed} inhomogeneous cosmological models. The models, called the {\it locally U(1)$\times$U(1) symmetric models} (or the {\it generalized Gowdy models}), are characterized by the existence of two commuting spatial {\it local} Killing vectors. For systematic investigations we first present a classification of possible spatial topologies in this class. We stress the significance of the locally homogeneous limits (i.e., the Bianchi types or the `geometric structures') of the models. In particular, we show a method of reduction to the natural reduced manifold, and analyze the equivalences at the reduced level of the models as dynamical models. Based on these fundamentals, we examine the influence of spatial topologies on dynamics by obtaining translation and reflection operators which commute with the dynamical flow in the phase space.Comment: 32 pages, 1 figure, LaTeX2e, revised Introduction slightly. To appear in CQ

Carbon storage in cacao (Theobroma cacao) plantations in Armero-Guayabal (Tolima, Colombia)

P?ginas 6-10El cambio clim?tico sigue siendo la principal amenaza de la humanidad hoy en d?a. Esta problem?tica se ha incrementado debido a las acciones humanas, como el uso de combustibles f?siles, la deforestaci?n y la degradaci?n. La comunidad mundial organizada ha establecido esquemas para mitigar este problema ambiental, por ejemplo el mecanismo de desarrollo limpio. Los sistemas agroforestales con cacao son considerados como mitigadores del cambio clim?tico por capturar carbono en biomasa, necromasa y suelos. Se estim? el almacenamiento y la fijaci?n de carbono en biomasa arriba del suelo y necromasa de cacaotales de 18 y 35 a?os de edad en el Centro Universitario Regional del Norte, en Armero-Guayabal (Tolima, Colombia) CURDN. Los cacaotales estudiados almacenaron 28.8 y 33.6 t C ha-1 en biomasa arriba del suelo a los 18 y 35 a?os, respectivamente, que arrojaron una tasa de fijaci?n promedio de 1.1 t C ha-1 a?o-1 . El carbono almacenado en necromasa ascendi? a 4.4 t ha-1 , con diferencias leves entre las edades de las plantaciones. Los sistemas agroforestales con cacao en Armero-Guayabal (Tolima, Colombia) tienen potencial para mitigar el cambio clim?tico al capturar carbono en biomasa y necromasa.ABSTRACT. Climate change holds as the current main threat of the humankind. This problem has being increasing by human actions such as the use of fossil fuels, deforestation and degradation. The organized world community has established schemes to mitigate this environmental problem, such as the Clean Development Mechanism. Agroforestry systems with cacao are considered as mitigating activities of climate change due to their capture of carbon in biomass and necromass. The carbon storage and fixation in aboveground biomass and necromass in cacao plantations of 18 and 35 years in the Centro Universitario Regional del Norte (CURDN), in ArmeroGuayabal (Tolima, Colombia) were estimated. The studied cacao plantations stored 28.8 and 33.6 t C ha-1 in aboveground biomass with an age of 18 and 35 years respectively, showing an average fixation rate of 1.1 t C ha-1 year-1 . The stored carbon in necromass was 4.4 t ha-1 , with slight differences between the ages of plantations. Agroforestry systems with cacao in Armero-Guayabal, Tolima, Colombia have the potential to mitigate climate change due its capture of atmospheric carbon in aboveground biomass and necromass

The Gowdy T3 Cosmologies revisited

We have examined, repeated and extended earlier numerical calculations of Berger and Moncrief for the evolution of unpolarized Gowdy T3 cosmological models. Our results are consistent with theirs and we support their claim that the models exhibit AVTD behaviour, even though spatial derivatives cannot be neglected. The behaviour of the curvature invariants and the formation of structure through evolution both backwards and forwards in time is discussed.Comment: 11 pages, LaTeX, 6 figures, results and conclusions revised and (considerably) expande