Global warming response options in Brazil's forest sector: Comparison of project-level costs and benefits

A project-level assessment of monetary and carbon costs and benefits for 5 classes of global warming response options in the forest sector is attempted for typical Brazilian conditions. Options considered are: silvicultural plantations (for pulp, charcoal and sawlogs), sustainable timber management and reduction of deforestation. Comparison of pulpwood and sawlog plantations with the vegetation characteristic of deforested areas indicates a modest carbon benefit. Plantations for charcoal can produce a substantial carbon benefit through fossil fuel substitution, but much of this calculated benefit disappears if discount rates greater than zero are applied to carbon. Sustainable timber management, when compared with existing forest, represents a net carbon loss, accumulation of carbon in wood products being insufficient to compensate for biomas

Bayesian analysis of finite mixture distributions using the allocation sampler

Finite mixture distributions are receiving more and more attention from statisticians in many different fields of research because they are a very flexible class of models. They are typically used for density estimation or to model population heterogeneity. One can think of a finite mixture distribution as grouping the observations into components from which they are assumed to have arisen. In certain settings these groups have a physical interpretation. The interest in these distributions has been boosted recently because of the ever increasing computer power available to researchers to carry out the computationally intensive tasks required in their analysis. In order to fit a finite mixture distribution taking a Bayesian approach a posterior distribution has to be evaluated. When the number of components in the model is assumed known this posterior distribution can be sampled from using methods such as Data Augmentation or Gibbs sampling (Tanner and Wong (1987) and Gelfand and Smith (1990)) and the Metropolis-Hastings algorithm (Hastings (1970)). However, the number of components in the model can also be considered an unknown and an object of inference. Richardson and Green (1997) and Stephens (2000a) both describe Bayesian methods to sample across models with different numbers of components. This enables an estimate of the posterior distribution of the number of components to be evaluated. Richardson and Green (1997) define a reversible jump Markov chain Monte Carlo (RJMCMC) sampler while Stephens (2000a) uses a Markov birth-death process approach sample from the posterior distribution. In this thesis a Markov chain Monte Carlo method, named the allocation sampler. This sampler differs from the RJMCMC method reported in Richardson and Green (1997) because the state space of the sampler is simplified by the assumption that the components' parameters and weights can be analytically integrated out of the model. This in turn has the advantage that only minimal changes are required to the sampler for mixtures of components from other parametric families. This thesis illustrates the allocation sampler's performance on both simulated and real data sets. Chapter 1 provides a background to finite mixture distributions and gives an overview of some inferential techniques that have already been used to analyse these distributions. Chapter 2 sets out the Bayesian model framework that is used throughout this thesis and defines all the required distributional results. Chapter 3 describes the allocation sampler. Chapter 4 tests the performance of the allocation sampler using simulated datasets from a collection of 15 different known mixture distributions. Chapter 5 illustrates the allocation sampler with real datasets from a number of different research fields. Chapter 6 summarises the research in the thesis and provides areas of possible future research

The evolving context of Brazil’s environmental policies in Amazonia

The context of Brazil’s environmental policies has changed in multiple ways over the past two decades, some positive for the environment and others not. Positive changes include creation of a Ministry of the Environment and a system of environmental licensing, increased organization of civil society, creation of reserves and demarcation of indigenous areas, and the advent of international conventions on climate and biodiversity. However, development projects in Brazilian Amazonia have circumvented environmental restrictions in various ways, and past and present modifications to the system are weakening environmental protection. The current hostility of the political climate in Brazil in environmental matters makes efforts to strengthen environmental policies even more dependent on careful selection of strategies. Making the best of instability by being prepared for conservation opportunities is one method, as is the use of science and technology in relevant areas. Understanding the complex nature of Brazilian bureaucracy is essential in this process. The value of environmental services provided by maintaining Amazon forest could be a key element in determining the future of environmental policy and of the forest

Dressed autoionising states and light-induced continuum structures in an intense laser field

Results are presented for Floquet calculations of photodetachment rates from a one-dimensional model atom irradiated by intense laser light. Light-induced quasibound states are found to originate from the movement of poles of the multichannel scattering matrix on the Riemann energy surface. The appearance of new bound states of the negative Hydrogen ion, recently predicted, is related to the motion of resonance poles that correspond to autoionising states in the absence of the field. A number of pole trajectories, leading to light-induced states, are discussed for the one-dimensional model atom. The Floquet method allows one to represent the wave function of a quantum system in a laser field, as an infinite sum of harmonic basis functions. In any practical calculation this infinite sum must be truncated. The consequences of representing the wave function, via the Floquet method, by a finite sum of harmonics is addressed. An illustration of these consequences is made by way of a number of representative calculations performed on a one-dimensional model atom. Results are presented of calculations performed to determine the influence of a laser field, of low to moderate intensity, upon the partial and total photodetachment rates of the negative Hydrogen ion, H(^-). Using the R-matrix Floquet method, a study is undertaken into the detachment of an electron from the ion, via multiphoton transitions through one of several autodetaching resonances of the ion. The discussion focuses on the influence of the laser field upon auto detaching pathways. It is found that the laser may induce structure into the continuum that does not exist in the absence of the laser field, or, conversely, may suppress field-free structure. In the latter case, the suppression of structure is related to the appearance of laser-induced degeneracies

Environmental policy in Brazilian Amazonia: Lessons from recent history

Tropical forest in Brazil, as in other countries, faces threats stemming from decision making that favors destructive development and gives only token consideration to lost environmental services and other impacts. History, particularly the most relevant period covering the recent years of rapid development in Amazonia, is a source of useful lessons for changing the decision-making process to favor outcomes that are less destructive and more sustainable. Development decisions set processes in motion with consequences extending far into the future, adding urgency to the task of assimilating these lessons. Decisions in the coming decade will determine the fate of Brazil’s Amazon forest, as is also the case for other countries that could benefit from the lessons of recent history in Brazil

Brazilian government violates Indigenous rights: What could induce a change?

The current presidential administration of Brazil has implemented a legislative agenda aimed at weakening protections of Indigenous peoples, in line with an ideological discourse and the direct participation of the armed forces in this process. This agenda has enabled invasions of Indigenous lands and a much higher COVID-19 mortality rate for Indigenous peoples when compared to non-Indigenous people. A bill recently approved by the Chamber of Deputies aims to extinguish all Indigenous lands established by the Brazilian government from 1988 onwards. This bill represents the official opening for violation of the rights of Indigenous peoples by the Bolsonaro administration and facilitates invasion of Indigenous lands. The president’s multiple efforts to weaken or deny protection of these peoples, to usurp their lands and to deny their rights to consultation on projects that affect them need to be judged by Brazil’s Federal Supreme Court, the UN Human Rights Council, the Inter-American Commission on Human Rights (IACHR), the Inter-American Court of Human Rights (IACtHR) and the International Criminal Court

Military forces and COVID-19 as smokescreens for Amazon destruction and violation of indigenous rights

The President of Brazil has adopted an anti-environmental stance since taking office in January 2019, weakening the rights of indigenous peoples and environmental legislation and militarizing the environmental and indigenous agencies. The president’s stance on the COVID-19 pandemic gives priority to economic development rather than to saving lives. The administration’s environment minister even suggested taking advantage of the media’s attention being focussed on the pandemic as an ‘opportunity’ to weaken environmental legislation. Here we argue that both the pandemic and the militarization of Brazil’s environmental protection have served as smokescreens to weaken environmental protections, and have also put Brazil’s indigenous peoples at risk and violated their rights

A personal experience of performing a systematic literature review

This paper describes the personal experience of two novice reviewers in developing and conducting a systematic literature review (SLR) in the field of medical ultrasound. The review was performed as part of a PhD study by the first author, which required the researcher to critically review all relevant studies in their specific research area. The review was conducted using a formal, scientific process and highlighted 20 relevant papers. Among the lessons learnt, undertaking an SLR was a time-consuming process. The search produced 1,987 papers, and screening the search yield was facilitated by using a pre-defined protocol. Extraction of data from each study was standardised and generated a 1-page summary of the key findings and methodology to facilitate comparisons of the included studies. The Critical Appraisal Skills Programme (CASP) tool was used for quality assessment. In the critical appraisal process, it is essential that reviewers have good baseline knowledge in the research subject, a solid understanding of the fundamentals of a robust research study including potential bias in research. With the great amount of information that a critical appraisal produces, good information management was key throughout the review to ensure the process was explicit and replicable and so that reviewers could justify their decisions. The methods and processes detailed in this report, as well as its lessons, are relevant to an SLR for any research subject