The objective of this research is to develop accurate forecasting models for chlorophyll-α concentrations at various depths in El Mar Menor, Spain. Chlorophyll-α plays a crucial role in assessing eutrophication in this vulnerable ecosystem. To achieve this objective, various deep learning forecasting techniques, including long short-term memory, bidirectional long short-term memory and gated recurrent uni networks, were utilized. The models were designed to forecast the chlorophyll-α levels with a 2-week prediction horizon. To enhance the models’ accuracy, a (...) sliding window method combined with a blocked cross-validation procedure for time series was also applied to these techniques. Two input strategies were also tested in this approach: using only chlorophyll-α time series and incorporating exogenous variables. The proposed approach significantly improved the accuracy of the predictive models, no matter the forecasting technique employed. Results were remarkable, with |$\overline{\sigma}$| values reaching approximately 0.90 for the 0.5-m depth level and 0.80 for deeper levels. The proposed forecasting models and methodologies have great potential for predicting eutrophication episodes and acting as decision-making tools for environmental agencies. Accurate prediction of eutrophication episodes through these models could allow for proactive measures to be implemented, resulting in improved environmental management and the preservation of the ecosystem. (shrink)

— We prescnt here a comparative study on the decay of chlorophyll a fluorescence yield in thylakoid membranes and photosystem 11 ‐enriched samples, measured with multifrequency cross‐correlation phase fluorometry. These measurements confirm the general conclusions of Van Mieghem ef al., obtained with a flash method, on the effects of reduction of the primary quinone acceptor on ChI a fluorescence yield of PSI. Different states of the reaction centers of PSII were produced by: pretreatment with sodium dithionite and mcthyl viologen (...) followed by laser illumination: the doubly reduced QA centers: with laser illumination or pretreatment with diuron: QA‐ centers; and the addition of micromolar concentration of dichlorobenzoquinonc : oxidized QA centers. The data were analyzed with Lorentzian distribution as well as with multiexponential fluorescence decay functions. The analysis with Lorcntzian distribution function showed that upon formation of QA. the major lifetime distribution peak shifted to longer lifetimes: from 0.25 ns to 1.66 ns and from 0.24 ns to 1.31 ns. However, when QAHZ was formed, the lifetime distribution peaks shifted back to shorter lifetimes both in thylakoids and PSIl membranes. Multiexponential analysis showed three lifetime components: fast, middle and slow. When QA was formed in PS11 centers, the amplitude of the fast Component decreased, but both thc amplitude and the lifetime of the middle component increased severalfold. However, when QA was doubly reduccd, the amplitude of the fast component increased and the amplitude of the middle component decreased: in addition, the lifetime of the slow component increased. All of the above results are consistent with the conclusions that PS11 charge separation is decreased when QA is formed and increased when doubly reduced QA is formed. Copyright © 1993, Wiley Blackwell. All rights reserved. (shrink)

The present paper claims that M. S. Tswett’s chromatographic adsorption analysis, which today is a ubiquitous and instrumentally sophisticated chemical technique, was either ignored or outright rejected by chemists and botanists in the first three decades of the twentieth century because it did not make sense in terms of accepted chemical theory or practice. Evidence for this claim is culled from consideration of the botanical and chemical context of Tswett’s technique as well as an analysis of the protracted debate over (...) Tswett’s chromatographic analysis of chlorophyll between him and Leon Marchlewski, a noted chlorophyll chemist of the period. In this way, the paper expands and amends what it calls the ‘textbook story’ of the early history of chromatography, examples of which may be found in historical notes in many textbooks of chemical instrumental analysis and numerous short articles in chemistry journals. The paper also provides an accessible introduction to the early history of chromatography for historians of science likely to know little or nothing about it. (shrink)

This paper is concerned with the problem of giving a correct analysis of function statements as they are used in biology. Examples of such statements are (1) The function of the myelin sheath is to insulate the nerve fiber and (2) The function of chlorophyll is to enable photosynthesis to take place. After criticizing analyses of such statements developed by Braithwaite, Nagel and Hempel an analysis is presented by the author. Finally the question of whether function statements are explanations (...) is discussed briefly. (shrink)

he theory o f natural selection provides a mechanistic, causal account of how living things came to look as if they had been designed for a purpose. So overwhelming is the appearance of purposeful design that, even in this Darwinian era when we know "better," we still find it difficult, indeed boringly pedantic, to refrain from teleological language when discussing adaptation. Birds' wings are obviously "for" flying, spider webs are for catching insects, chlorophyll molecules are for photosynthesis, DNA molecules (...) are for... What are DNA molecules for? The question takes us aback. In my case it touches off an almost audible alarm siren in the mind. If we accept the view of life that I wish to espouse, it is the forbidden question. DNA is not "for" anything. If we wish to speak teleologically, all adaptations are for the preservation of DNA; DNA itself just is. Following Williams, I have advocated this view at length, and I do not want to repeat myself here. Instead I shall try to clear up an important misunderstanding of the view, a misunderstanding that has constituted an unnecessary barrier to its acceptance. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:F/Actual Knowing:Putting Facts and Values in PlaceHolmes Rolston III (bio)Knowing needs to be actualized, an act of ours, yet also a discovery of what is actually, factually there. In place ourselves, we manage some awareness of other places. Agents in our knowing, we co-respond, and this emplaces us. But we humans have powers of dis-placement too, of taking up, whether empathetically or objectively, the situations of others, other humans, (...) sometimes others than humans. How do our facts depend on our acts? Do we humans always put in place, or sometimes find put, placed there before us, what we variously value on Earth?To put this provocatively: We need to "green" our beliefs; but every educated person knows that nothing out there is really "green." "Seeing green" is an interaction experience. Perhaps this perceptual experience is a model for the whole: all of our human concepts and percepts color up the world. This is true alike of facts and of values, discoveries and evaluations. Such knowing might be well enough placed, but it is always and only "placed." Our geographical position controls our epistemic composition. Epistemology is inevitably anthropocentric; we are always located in the center of our knowing.But what if the "green" we see is mostly chlorophyll? Photosynthesis is not something we can see at all. In place on Earth, we humans breathe oxygen and would die in minutes without it; we depend on photosynthesis at the foundation of our food chains. We know our own respiratory [End Page 137] and trophic interactions with the plants, and this not simply at the native range experiences of breathing and eating. We have figured out the oxygen/carbon-dioxide/water cycles taking place at molecular levels.Now it seems, however, that we are discovering ourselves placed where the facts are bigger than our acts, including our respiratory (and perceptual) interactions; these extend systemically and are hardly anthropocentric. Epistemologically, we have more to evaluate. "Greening" our belief, environmentally grounding it, will require knowing and appropriately respecting these vital life processes—of which we are a part, but which also are "in place" and "take place" apart from us.1. Embodied, Knowledgeable PersonsWhatever knowledge we gain has to "come through" at our native range. That seems uncontroversial, but what are the implications? Knowledge is relative to our location, our embodiment, our size, our terrestrial habitat. This situation constricts, it may be claimed, what can "come through." Mark Johnson concludes: "Our consciousness and rationality are tied to our bodily orientations and interactions in and with our environment. Our embodiment is essential to who we are, to what meaning is, and to our ability to draw rational inferences and to be creative." He urges us to "put the body back into the mind," that is, epistemologically, to become aware of how the body is there, willy-nilly (1987, xxxviii, xxxvi). Joining with George Lakoff, he claims: "Reason, even in its most abstract form, makes use of, rather than transcends, our animal nature" (Lakoff and Johnson 1999, 4).Katherine Hayles continues: "To be incorporated within a different body would be to live in a different world." She features "interactivity" and explains:Interactivity foregrounds rather than obscures the importance of embodiment. In the interaction model, the body does more than provide a biological support system for the mind. Interaction is possible only because we are embodied, and the precise conditions of our embodiment have everything to do with the nature of those interactions. The range and nature of sensory stimuli available to us, the contexts that affect how those sensory stimuli achieve meaning, the habituated movements and postures that we learn through culture and that are encoded for gender, ethnicity, and class—all affect how learning takes place and how the world comes into being for us.(1995, 56) [End Page 138]All this seems true, if one means that with reincarnation our native range experiences would be different. Wolves have keen noses and with them they experience, if you like, a different world. But the survival value of wolf noses, a situated knowledge for them, is equally true for humans, wolves, and elk, because all three... (shrink)

Half a million species of plants could be existing in the world. Classification of plants based on leaf features is a critical job as feature extraction from binary images of leaves may result in duplicate identification. However, leaves are an effective means of differentiating plant species because of their unique characteristics like area, diameter, perimeter, circularity, aspect ratio, solidity, eccentricity, and narrow factor. This paper presents the extraction of plant leaf gas alongside other features from the camera images or a (...) dataset of images by applying a convolutional neural network. The extraction of leaf gas enables identification of the actual level of chlorophyll and nitrogen which may help to interpret future predictions. Our contribution includes the study of texture and geometric features, analyzing ratio of Ch and N in both healthy and dead leaves, and the study of color-based methods via CNN. Several steps are included to obtain the results: image preprocessing, testing, training, enhancement, segmentation, feature extraction, and aggregation of results. A vital contrast of the results can be seen by considering the kind of image, whether a healthy or dead leaf. (shrink)

Lead (Pb) contamination of the environment is an important human health problem. Children are vulnerable to Pb toxicity; it causes damage to the central nervous system and, in some extreme cases, can cause death. Lead is widespread, especially in the urban environment, and is present in the atmosphere, soil, water and food. Pb tends to accumulate in surface soil because of its low solubility, mobility, and relative freedom from microbial degradation of this element in the soil. Lead is present in (...) soil as a result to weathering and other pedogenic processes acting on the soil parent material; or from pollution arising caused by the anthropogenic activities; such as mining, smelting and waste disposal; or through the adoption of the unsafe and unethical agricultural practices such as using of sewage sludge, and waste water in production of vegetable crops or cultivation of vegetables near highways and industry regions. Lead concentrations are generally higher in the leafy vegetables than the other vegetables. Factors affecting lead uptake included its concentration in the soil, soil pH, soil type, organic matter content, plant species, and unsafe agriculture practices. Generally, as Pb concentration increased; dry matter yields of roots, stems and leaves as well as total yield decreased. The mechanism of growth inhibition by lead involve: a decrease in number of dividing cells, a reduction on chlorophyll synthesis, induced water stress to plants, and decreased NO 3 - uptake, reduced nitrate and nitrite reductase activity, a direct effect of lead on protein synthesis, a decrease on the uptake and concentration of nutrients in plants. The strategies to minimize Pb hazard can be represented in: (a) Phytoremediation, through natural plants are able to bio-accumulate Pb in their above–ground parts, which are then harvested for removal such as, using Indian Mustard (Brassica juncea), Ragweed (Ambrosia artemisiifolia), Hemp Dogbane (Apocynum cannabium), or Poplar trees, which sequester lead in its biomass. (b) Good and ethical agricultural practices such as cultivation of vegetables crops as far from busy streets or highways and industry regions as well as nonuse of sewage sludge and waste water in cultivated soils. (c) Increasing the absorptive capacity of the soil by adding organic matter and humic acid. (d) Growing vegetable crops and cultivars with a low potential to accumulate lead, especially in soils exposed to atmospheric pollution. (e) Washing of leafy vegetables by water containing 1 % vinegar or peeling roots, tubers, and some fruits of vegetables before consumption may be an important factor in reducing the lead concentration. (shrink)

We propose a new account of calibration according to which calibrating a technique shows that the technique does what it is supposed to do. To motivate our account, we examine an early twentieth-century debate about chlorophyll chemistry and Mikhail Tswett’s use of chromatographic adsorption analysis to study it. We argue that Tswett’s experiments established that his technique was reliable in the special case of chlorophyll without relying on either a theory or a standard calibration experiment. We suggest that (...) Tswett broke the experimenters’ regress by appealing to material facts in the common ground for chemists at the time. (shrink)

The photosynthetic organelle of algae and plants (the plastid) traces its origin to a primary endosymbiotic event in which a previously non‐photosynthetic protist engulfed and enslaved a cyanobacterium. This eukaryote then gave rise to the red, green and glaucophyte algae. However, many algal lineages, such as the chlorophyll c‐containing chromists, have a more complicated evolutionary history involving a secondary endosymbiotic event, in which a protist engulfed an existing eukaryotic alga (in this case, a red alga). Chromists such as diatoms (...) and kelps then rose to great importance in aquatic habitats. Another algal group, the dinoflagellates, has undergone tertiary (engulfment of a secondary plastid) and even quaternary endosymbioses. In this review, we examine algal diversity and show endosymbiosis to be a major force in algal evolution. This area of research has advanced rapidly and long‐standing issues such as the chromalveolate hypothesis and the extent of endosymbiotic gene transfer have recently been clarified. BioEssays 26:50–60, 2004. © 2003 Wiley Periodicals, Inc. (shrink)

Cyanolichens are symbiotic organisms involving cyanobacteria and fungi (bipartite) or with the addition of an algal partner (tripartite). Cyanolichens are known for their heightened susceptibility to environmental pollution. We focus here on the impacts on cyanolichens due to rising air pollution; we are especially interested in the role of sulfur dioxide on cyanolichen biology. Cyanolichens due to air pollution including sulfur dioxide exposure, show symptomatic changes including degradation of chlorophyll, lipid membrane peroxidation, decrease in ATP production, changes in respiration (...) rate, and alteration of endogenous auxins and ethylene production, although symptoms are known to vary with species and genotype. Sulfur dioxide has been shown to be damaging to photosynthesis but is relatively benign on nitrogen fixation which proposes as a hypothesis that the algal partner may be more in harm’s way than the cyanobiont. In fact, the Nostoc cyanobiont of sulfur dioxide-susceptible Lobaria pulmonaria carries a magnified set of sulfur (alkane sulfonate) metabolism genes capable of alkane sulfonate transport and assimilation, which were only unraveled by genome sequencing, a technology unavailable in the 1950–2000 epoch, where most physiology- based studies were performed. There is worldwide a growing corpus of evidence that sulfur has an important role to play in biological symbioses including rhizobia-legumes, mycorrhizae-roots and cyanobacteria-host plants. Furthermore, the fungal and algal partners of L. pulmonaria appear not to have the sulfonate transporter genes again providing the roles of ambient-sulfur (alkanesulfonate metabolism etc.) mediated functions primarily to the cyanobacterial partner. In conclusion, we have addressed here the role of the atmospheric pollutant sulfur dioxide to tripartite cyanolichen viability and suggest that the weaker link is likely to be the photosynthetic algal (chlorophyte) partner and not the nitrogen-fixing cyanobiont. (shrink)

In this work it is presented a methodology for the development of a pattern recognition system using classification methods as discriminant analysis and artificial neural networks. In this methodology, the statistical analysis is contemplated, with the purpose of retaining the observations and the important characteristics that can produce an appropriate classification, and allows, as well, to detect outliers’ observations, multicolinearity between variables, among other things. Chlorophyll a fluorescence OJIP signals measured from Pisum sativum leaves belonging to different drought stress (...) resistance groups are correctly classified using the proposed here methodology. (shrink)

In this article, David Shemin, who is now in retirement, describes how in 1944 he ingested 66 g of 15N‐labeled glycine in order to determine the half‐life of hemoglobin and other blood proteins. The ramifications of the experiment led to the unravelling of the biosynthesis of porphyrins and the role of glycine and α‐aminolevulinic acid in heme, vitamin B12 and chlorophyll synthesis.