Chemical control of respiration in chronic respiratory failure

As with most prefaces, this is written after the main work, but it is still intended to be read first. It should serve two purposes, which I hope can be combined without conflict, the first to act in the manner of a Shakespearean chorus, setting the scene for the main play, and the second to allow the author to present a purely personal view of the motives underlying this work.Science has a multiplicity of definitions but the conventional Concise Oxford Dictionary one of "systematic and formulated knowledge's will suffice as a start. Karl Pearson, in his book "The Grammar of Science" extends his definition to embrace the scientific method. He states "the classification of facts, the recognition of their sequence and relative significance is the function of science ". He deprecates the idea that science is merely a compendium of useful knowledge, and elevates the scientific frame of mind (by which he means the forming of judgments based upon facts, unbiased by personal feeling) as being sufficiently justified in itself. This seems to me to be an essentially moral argument, for the practice of logical thinking, which is my interpretation of Pearson's "scientific frame of mind ", appears to invoke no necessity for justification by results. This would not imply that all such results of logical thought are necessarily good, in a moral sense, but I would submit that intellectual freedom, both to reason and to dream, is in itself morally desirable.For most people, however, dreams and reasons must start from a present reality, and in this case the reality has been a complex problem in a disturbance of a physiological control mechanism. How does carbon dioxide fail to stimulate the breathing in patients with severe chronic bronchitis?For the application of Pearson's definition it is apparent that the facts which are to be classified must first be ascertained. What are facts ? I have no full answer, for any definition must involve truth, and real knowledge of truth eludes me. However, I can substitute for this unattainable objective of truth, by using what I believe is an honest assessment of scientific method. I may never really know anything, but if I make an honest observation, and consider to the best of my ability the possibilities of error in my observation, in my submission, I have made a contribution whose value will depend upon my abilities. My interpretation of this observation, or in Pearson's terms, my classification of my "fact" and its placement in sequence and recognition of its significance, will always be open to question, but the care with which the observation was made must indicate its proximity to infallibility. In this sense, therefore, I can merely state my complete agreement with Gray "to those physiologists whose imperishable observations provoke my perishable interpretations".It would follow, therefore, that in my view the accuracy of the observation or the "fact ", is of paramount importance. Nonetheless, observations without thought for their use, or interpretation, are unlikely to provoke a spirit of enquiry to seek new observations. A science which seeks to establish facts alone would, in my view, be sterile.In the present study the difficulties of the problem impose their own discipline. To investigate a control system, it is desirable to study the responses of the system to known variations in a stimulus. To know about something properly, there is no substitute for measurement, to paraphrase Lord Kelvin. In this problem, therefore, measurements of both response and stimulus, and then attempts to relate these in some mathematical form are made. However, the basic problem lies in the possibility of error in these primary physical measurements of both stimulus and response. Furthermore, the accuracy with which we can measure these values, at least in the case of the stimulus, is of the same order as that which provokes a response in the stimulated system.The manner in which I have attempted to face these problems will be shown in the following pages. I am conscious of many defects in the methods I have used, and my conclusions are drawn with a full knowledge that they are only justifiable in so far as they take account of their foundations in these possibly perishable observations

Automatic Recognition of Light Microscope Pollen Images

This paper is a progress report on a project aimed at the realization of a low-cost, automatic, trainable system "AutoStage" for recognition and counting of pollen. Previous work on image feature selection and classification has been extended by design and integration of an XY stage to allow slides to be scanned, an auto focus system, and segmentation software. The results of a series of classification tests are reported, and verified by comparison with classification performance by expert palynologists. A number of technical issues are addressed, including pollen slide preparation and slide sampling protocols

Revisiting the role of high-energy Pacific events on the environmental and cultural history of Easter Island (Rapa Nui)

Pacific islands are spread over thousands of kilometers of the Oceanic Basin and are characterized by similar ecological features but very diverse geologic origins, from steep volcanoes to flat coral atolls. Several climatic phases have been shared among the region within the last 1000 years. Numerous and abrupt societal and cultural changes during the same period have been described for islands separated by thousands of kilometers. Conspicuous societal changes have been exclusively attributed to the main climatic patterns (changes in precipitation and temperature). The possible role of tsunamis and the occurrence of large volcanic eruptions as regional societal modulators, however, have traditionally received little attention from archeologists, mainly due to the difficulty of recognizing them in the sedimentary and geomorphological records. We explore the potential influence of the most important high-energy events in the Pacific on Polynesian societal changes, with a special focus on Easter Island. For example, the extreme Samalas eruption in AD1257 may have been an indirect driver of the sudden population decline, land degradation and decreased food resources on many Pacific islands between AD1250 and 1300, and the Kuwae eruption in AD1450 may have triggered the synchronous end of long voyaging expeditions across the Pacific. Important paleotsunamis have had unquestionable impacts on coastal and seafaring societies. A direct effect of the main eruptions of the last millennia (AD1257 and 1453) on Easter Island has not yet been identified by any record, but we have calculated, the likelihood of destructive tsunamis with an estimated period of recurrence for large events of less than a century.This insight is new and needs to be taken into account to complement what we already know about Easter Island cultural history and archeological sites, especially those in vulnerable coastal locations

Patterns of modern pollen and plant richness across northern Europe

Sedimentary pollen offers excellent opportunities to reconstruct vegetation changes over past millennia. Number of different pollen taxa or pollen richness is used to characterise past plant richness. To improve the interpretation of sedimentary pollen richness, it is essential to understand the relationship between pollen and plant richness in contemporary landscapes. This study presents a regional-scale comparison of pollen and plant richness from northern Europe and evaluates the importance of environmental variables on pollen and plant richness. We use a pollen dataset of 511 lake-surface pollen samples ranging through temperate, boreal and tundra biomes. To characterise plant diversity, we use a dataset formulated from the two largest plant atlases available in Europe. We compare pollen and plant richness estimates in different groups of taxa (wind-pollinated vs. non-wind-pollinated, trees and shrubs vs. herbs and grasses) and test their relationships with climate and landscape variables. Pollen richness is significantly positively correlated with plant richness (r = 0.53). The pollen plant richness correlation improves (r = 0.63) when high pollen producers are downweighted prior to estimating richness minimising the influence of pollen production on the pollen richness estimate. This suggests that methods accommodating pollen-production differences in richness estimates deserve further attention and should become more widely used in Quaternary pollen diversity studies. The highest correlations are found between pollen and plant richness of trees and shrubs (r = 0.83) and of wind-pollinated taxa (r = 0.75) suggesting that these are the best measures of broad-scale plant richness over several thousands of square kilometres. Mean annual temperature is the strongest predictor of both pollen and plant richness. Landscape openness is positively associated with pollen richness but not with plant richness. Pollen richness values from extremely open and/or cold areas where pollen production is low should be interpreted with caution because low local pollen production increases the proportion of extra-regional pollen. Synthesis. Our results confirm that pollen data can provide insights into past plant richness changes in northern Europe, and with careful consideration of pollen-production differences and spatial scale represented, pollen data make it possible to investigate vegetation diversity trends over long time-scales and under changing climatic and habitat conditions.Peer reviewe

Pollen and spores as biological recorders of past ultraviolet irradiance

Solar ultraviolet (UV) irradiance is a key driver of climatic and biotic change. Ultraviolet irradiance modulates stratospheric warming and ozone production, and influences the biosphere from ecosystem-level processes through to the largest scale patterns of diversification and extinction. Yet our understanding of ultraviolet irradiance is limited because no method has been validated to reconstruct its flux over timescales relevant to climatic or biotic processes. Here, we show that a recently developed proxy for ultraviolet irradiance based on spore and pollen chemistry can be used over long (105 years) timescales. Firstly we demonstrate that spatial variations in spore and pollen chemistry correlate with known latitudinal solar irradiance gradients. Using this relationship we provide a reconstruction of past changes in solar irradiance based on the pollen record from Lake Bosumtwi in Ghana. As anticipated, variations in the chemistry of grass pollen from the Lake Bosumtwi record show a link to multiple orbital precessional cycles (19-21 thousand years). By providing a unique, local proxy for broad spectrum solar irradiance, the chemical analysis of spores and pollen offers unprecedented opportunities to decouple solar variability, climate and vegetation change through geologic time and a new proxy with which to probe the Earth system

Holocene landscape intervention and plant food production strategies in island and mainland Southeast Asia

In the areas adjacent to the drowned Pleistocene continent of Sunda - present-day Mainland and Island SE Asia - the Austronesian Hypothesis of a diaspora of rice cultivators from Taiwan ~4200 years ago has often been linked with the start of farming. Mounting evidence suggests that these developments should not be conflated and that alternative explanations should be considered, including indigenous inception of complex patterns of plant food production and early exchange of plants, animals, technology and genes. We review evidence for widespread forest disturbance in the Early Holocene which may accompany the beginnings of complex food-production. Although often insubstantial, evidence for incipient and developing management of rainforest vegetation and of developing complex relationships with plants is present, and early enough to suggest that during the Early to mid-Holocene this vast region was marked by different approaches to plant food production. The trajectory of the increasingly complex relationships between people and their food organisms was strongly locally contingent and in many cases did not result in the development of agricultural systems that were recognisable as such at the time of early European encounters. Diverse resource management economies in the Sunda and neighbouring regions appear to have accompanied rather than replaced a reliance on hunting and gathering. This, together with evidence for Early Holocene interaction between these neighbours, gives cause for us to question some authors continued adherence to a singular narrative of the Austronesian Hypothesis and the 'Neolithisation' of this part of the world. It also leads us to suggest that the forests of this vast region are, to an extent, a cultural artefact

Modern pollen rain predicts shifts in plant trait composition but not plant diversity along the Andes–Amazon elevational gradient

This is the final version. Available on open access from Wiley via the DOI in this record. Aims: Terrestrial ecosystems are changing in biodiversity, species composition and functional trait composition. To understand the underlying causes of these changes and predict the long-term resilience of the ecosystem to withstand future disturbances, we can evaluate changes in diversity and composition from fossil pollen records. Although diversity can be well estimated from pollen in temperate ecosystems, this is less clear for the hyperdiverse tropics. Moreover, it remains unknown whether functional composition of plant assemblages can be accurately predicted from pollen assemblage composition. Here, we evaluate how community-weighted mean (CWM) traits and diversity indices change along elevation. Location: Amazon–Andes elevation gradient in Peru. Methods: We used 82 modern pollen samples and 59 vegetation plots along the elevation gradient, and calculated CWM traits and diversity indices for each pollen sample and vegetation plot. We also quantified the degree to which taxa are over- or underrepresented by their pollen, by dividing the relative pollen abundance by the relative basal area abundance in the nearby vegetation survey plots (i.e. the R-rel values). Results: We found that CWM wood density increased, and CWM adult height and leaf area decreased with elevation. This change was well predicted by pollen assemblages, indicating that CWM trait–environment relationships based on pollen abundance data provide meaningful results. Diversity (richness, Shannon and Simpson) decreased with elevation for vegetation plots, but these trends could not be observed from pollen assemblages. Conclusions: Our results demonstrate that more research is needed to develop methods that lead to accurate diversity estimates from pollen data in these tropical ecosystems, but that CWM traits can be calculated from pollen data to assess spatial shifts in functional composition. This opens opportunities to calculate CWM traits from fossil pollen data sets in the tropics, with broad implications for improving our understanding and predictions of forest dynamics, functioning and resilience through time.Nederlandse Organisatie voor Wetenschappelijk Onderzoe