RESOLVING THE QUESTION OF DOUBT: GEOMETRICAL DEMONSTRATION IN THE MEDITATIONS

The question of what Descartes did and did not doubt in the Meditations has received a significant amount of scholarly attention in recent years. The process of doubt in Meditation I gives one the impression of a rather extreme form of skepticism, while the responses Descartes offers in the Objections and Replies make it clear that there is in fact a whole background of presuppositions that are never doubted, including many that are never even entertained as possible candidates of doubt. This paper resolves the question of this undoubted background of rationality by taking seriously Descartes’ claim that he is carrying out demonstrations modeled after the great geometers. The rational order of geometrical demonstration demands that we first clear away previous demonstrations not proven with the certainty necessary for genuine science. This is accomplished by the method of doubt, which is only applied to the results of possible demonstrations. What cannot be doubted are the very concepts and principles employed in carrying out geometrical demonstration, which enable it to take place. It would be senseless to ask whether we can doubt the essential components of the structure through which questioning, doubting, and demonstration are made possible

Student effort and educational attainment: Using the England football team to identify the education production function.

We use a sharp, exogenous and repeated change in the value of leisure to identify the impact of student effort on educational achievement. The treatment arises from the partial overlap of the world’s major international football tournaments with the exam period in England. Our data enable a clean difference-in-difference design. Performance is measured using the high-stakes tests that all students take at the end of compulsory schooling. We find a strongly significant effect: the average impact of a fall in effort is 0.12 SDs of student performance, significantly larger for male and disadvantaged students, as high as many educational policies.student effort, educational achievement, schools

Descartes’ Atomism of Thought: A Solution to the Puzzle about True and Immutable Natures

Central to Descartes’ philosophy is a view about immutable essences and eternal truths. After mentioning a Platonist account of recollection in Meditation V, Descartes declares that the ideas we have of mathematical notions “are not my invention but have their own true and immutable natures” (AT VII, 64/CSM II, 44).Descartes claims that other important philosophical notions, such as God, mind, body, and human free will (AT VII, 68; AT VIII-2, 348; AT III, 383; AT VII, 433, respectively), also have immutable natures or essences. Although Descartes says a good many things about this view, nowhere does he offer definitive doctrine on the matter, and in fact frequently confuses his reader with apparently inconsistent pronouncements about immutable natures and eternal truths. In this essay, I focus on the immutable natures and propose a solution to two of the main problems associated with Descartes’ position, the metaphysical status of immutable natures and the purported indivisibility of their existence as ideas in the mind

Self-stigma, Stress, and Smoking among African American and American Indian Female Smokers: An Exploratory Qualitative Study

Research suggests that negative emotions and difficulty coping with stressful events might impede women’s ability to quit smoking. This study uses qualitative methods to explore interrelationships between smoking behavior and negative emotions among a sample of racial/ethnic minority female smokers with the aims of theory-building and hypothesis generation. Data were derived from a larger study involving sixteen focus groups with current and former smokers from ethnic minority communities. The present study consisted of three focus groups of female African American and American Indian smokers (N = 16). Data was analyzed following standard methods for in vivo coding of qualitative data. Consistent with prior research, participants reported using smoking as a tool to cope with stress and negative emotions. Deprivation from smoking was associated with negative states such as anger, irritability, and distress. However, continued smoking was also a source of negative emotion, as women felt shame, guilt and low self-esteem over their inability to quit, which was perceived by some as indicative of weakness. These negative self-perceptions are consistent with stigmatized views of smokers held by the public. Women also expressed feelings of defiance about their smoking despite pressure to quit and identified external factors which contributed to their inability to quit. The negative emotions, self-stigma and shame experienced by low income American Indian and African American women smokers may contribute to continued smoking and disrupt quit attempts. Additional research is needed in order to develop effective tobacco cessation interventions for this group

Concentrating on Carbon Concentration in Algae

Carbon Concentrating Mechanisms Improve Photosynthesis Rates in Low-Carbon Environments. CCMs allow the aggregation of carbon near the site of rubisco, that way even small amounts of available carbon are being utilized. Yes, this is important to you! Albeit somewhat indirectly, but massively nonetheless! Algae are a driving force behind the global carbon cycle, they sequester CO2 in the oceans. Understanding the mechanisms behind the tiny marine alga O. tauri gives us a better understanding of a vital global process

Identifying Genes Influencing the Efficiency of Photosynthesis

Photosynthesis adapts to environmental conditions over time.¹ Varying environmental conditions lead to stress accumulation on the plant.² A genetic library has been assembled for forward genetic screening of Arabidopsis thaliana.³ Arabidopsis Thaliana is a model plant used as a model organism in growth experiments. This research project aims to identify and analyze candidate genes that impact the efficiency of photosynthesis. These genes can be transplanted into commercial crops to increase efficiency of photosynthesis and crop yields

Investigating the link between fermentation and H2 production in the green alga Chlamydomonas reinhardtii

During anoxia, the green alga Chlamydomonas reinhardtii activates various ill-defined fermentation pathways leading to the production of hydrogen, formate, acetate and ethanol. A bioinformatic survey was performed to look for C. reinhardtii genes potentially involved in fermentation that could compete for carbon and reductant, with a view to increasing H2 yields by metabolic engineering. Antibodies were raised against the predicted NAD+-dependent D-lactate dehydrogenase (LDH), pyruvate decarboxylase (PDC3), pyruvate-formate lyase (PFL1), pyruvate synthase/pyruvate:ferredoxin oxidoreductase (PFOR), pyruvate dehydrogenase E1 α components (PDC1 and PDC2) and a bifunctional acetaldehyde/alcohol dehydrogenase (ADH1). These antibodies were used to improve metabolic models by providing information about localisation, extending previous studies to include analysis of the cytoplasmic fraction and putative LDH. Additionally, it was demonstrated that the majority of enzymes are constitutively present, even during photoautotrophic growth where active lactate, formate and ethanol production pathways were found. Artificial microRNA technology was used to knockdown PFL1, whose gene product catalyses the conversion of pyruvate to acetyl-CoA and formate. PFL1-knockdown had no impact upon H2 evolution during sulphur-deprivation, but caused a decrease in the excretion of formate and ethanol, also revealing a pathway for production of 3-hydroxybutyrate, a metabolite not previously detected in this alga. Additionally amiRNA knockdown was used to provide direct evidence for a PDC3 catalysed pathway during sulphur-deprivation. PDC3-knockdown led to the re-direction of flux via PFL1 and a decrease in H2 production rates. Inhibiting both the PFL1 and PDC3 catalysed pathways did not improve upon wild type yields of H2 but instead re-directed carbon flux to the production of lactate and alanine. Overall these data show amiRNA is an effective method for down regulating metabolic pathways controlled by PFL1 and PDC3. However if H2 yields in C. reinhardtii are to be significantly improved by metabolic engineering it will likely require the knockdown of multiple fermentative pathways

Insights into C4 metabolism from comparative deep sequencing.

C4 photosynthesis suppresses the oxygenation activity of Ribulose Bisphosphate Carboxylase Oxygenase and so limits photorespiration. Although highly complex, it is estimated to have evolved in 66 plant lineages, with the vast majority lacking sequenced genomes. Transcriptomics has recently initiated assessments of the degree to which transcript abundance differs between C3 and C4 leaves, identified novel components of C4 metabolism, and also led to mathematical models explaining the repeated evolution of this complex phenotype. Evidence is accumulating that this complex and convergent phenotype is partly underpinned by parallel evolution of structural genes, but also regulatory elements in both cis and trans. Furthermore, it appears that initial events associated with acquisition of C4 traits likely represent evolutionary exaptations related to non-photosynthetic processes.We thank the BBSRC for grant BB/1002243/1 and the EU 3to4 program for financial support.This is the accepted manuscript. The final version is available at http://www.sciencedirect.com/science/article/pii/S1369526615000680