Immediation II

All “media-tion” stages and distributes real, embodied – that is, immediate, events. The concept of immediation entails that cultural, technical, aesthetic objects, subjects, and events can no longer be abstracted from the ways in which they contribute to and are changed by broader ecologies. Immediation I and II seek to engage the entwined questions of relation, event and ecology from outside already claimed territories, nomenclature and calls to action

Aerospace Medicine and Biology - A cumulative index to a continuing bibliography

Cumulative index for abstracts of NASA documents on aerospace medicine and biolog

Automatic discovery of complex causality

This study entails the understanding of and the development of a computational method for automatically extracting complex expressions in language that correspond to event to event sequential relations in the real world. We here develop component procedures of a system that would be capable of taking raw linguistic input (such as those from narrative writings or social network data), and find real-world semantic relations among events. Such an endeavor is applicable to many types of sequential relations, for which we use causality as a case study, both for its importance as a prominent type of sequential relation between events, as well as for its general prevalence in natural language. But we also demonstrate that the idea is also applicable in principle to other major types of event to event relations, such as reciprocity. The study primarily focuses on those types of causalities that contain complex structures and require in-depth linguistic analyses to discover and extract. Designing an automated method for the extraction of structurally complex causal expressions entails methodologies and theories that are beyond conventional methods used in computational semantics. The classes of adjunctive causal structure, and embedded causal structure are types that are hard to access using traditional methods, but more amenable for methods developed in this study. The principal procedures employed for the extraction of these are a heavily mod- ified form of Hidden Markov Model (HMM), which we use to deal with causal structures that have sequentially complex makeup. We also designed a highly modified Genetic Algo- rithm (GA) adapted for embedded context-free structures, used to rank and extract those causal structures that have deep embedding at the syntax-semantics interface. These will be reformulated, augmented, and explored in depth. With these methods using unsupervised and semi-supervised learning, we were able to obtain reasonable results in terms of discrimination of causal pairs ⟨ei,ej⟩ pairs and some longer chains of causation from corpora. From these results, we were also able to perform additional linguistic analysis over their theoretical semantic structure, and observe aspects of each that allows us to sub-classify the relations according to standard ideas in formal logic as well as from behavioral psychology. These methods would be critical to a system for building a graph theoretic representation of a social network, from corpora produced by entities within that network, which would utilize the methods described in this project, and similar approaches can be extended to model and discover other types of complex event- relations. These types of fundamental technologies, would in turn, help us to design and build the types of on-line and mobile services that provide increased machine awareness of user behavior and to be able to target and cater to users individually

Biological Invasions in South Africa

This open access volume presents a comprehensive account of all aspects of biological invasions in South Africa, where research has been conducted over more than three decades, and where bold initiatives have been implemented in attempts to control invasions and to reduce their ecological, economic and social effects. It covers a broad range of themes, including history, policy development and implementation, the status of invasions of animals and plants in terrestrial, marine and freshwater environments, the development of a robust ecological theory around biological invasions, the effectiveness of management interventions, and scenarios for the future. The South African situation stands out because of the remarkable diversity of the country, and the wide range of problems encountered in its varied ecosystems, which has resulted in a disproportionate investment into both research and management. The South African experience holds many lessons for other parts of the world, and this book should be of immense value to researchers, students, managers, and policy-makers who deal with biological invasions and ecosystem management and conservation in most other regions

Chemical identification of dominance pheromones in Mozambique tilapia males

Fishes use pheromones (intraspecific chemical messages) to coordinate reproduction, migration and social interactions but their identity is rarely known. In the Mozambique tilapia (Oreochromis mossambicus), a social, lek-breeding cichlid, reproduction and male aggression are mediated through urinary cues released by dominant males. The main goal of this thesis was the chemical identification of such pheromones and establishment of their function(s). Two steroid glucuronates (5β-pregnane-3α,17,20β-triol 3-glucuronate and its 20α-epimer) were identified as the most potent odorants in male urine. Both steroids act, via a specific olfactory receptor mechanism, on the females’ endocrine axis, stimulating oocyte maturation. However, in contrast to dominant male urine, these steroids on their own do not reduce male aggression in receivers, suggesting that multiple, as yet unidentified, compounds are likely responsible for this effect. In conclusion, dominant tilapia males release pregnanetriol glucuronates via their urine as a sex pheromone, likely to synchronize spawning and enhance reproductive success; Resumo: Indentificação química das feromonas de dominância dos machos da tilápia moçambicana Os peixes usam feromonas (mensagens químicas intra-específicas) para coordenar a reprodução, migrações e interações sociais, cuja identidade é pouco conhecida. Na tilápia moçambicana (Oreochromis mossambicus), um ciclídeo social que se reproduz em agregações, a reprodução e agressão entre machos são mediados por odores libertados pela urina de machos dominantes. O objetivo principal desta tese é determinar a identidade e função destes. Os esteróides 5β-pregnane- 3α,17,20β-triol 3-glucurónido e o seu epímero 20α foram identificados como os compostos mais potentes presentes na urina de machos. Ambos atuam no eixo endócrino reprodutor das fêmeas através de um recetor olfativo específico e estimulam a maturação dos ovócitos. Ao contrário da urina dos machos, estes esteróides por si só não reduzem a agressão dos machos recetores, sugerindo a presença de múltiplos compostos, ainda por identificar, responsáveis por este efeito. Conclui-se que os machos dominantes da tilápia libertam uma feromona sexual através da urina que sincroniza a reprodução e melhora o seu sucesso reprodutor

Biological Invasions in South Africa

This open access volume presents a comprehensive account of all aspects of biological invasions in South Africa, where research has been conducted over more than three decades, and where bold initiatives have been implemented in attempts to control invasions and to reduce their ecological, economic and social effects. It covers a broad range of themes, including history, policy development and implementation, the status of invasions of animals and plants in terrestrial, marine and freshwater environments, the development of a robust ecological theory around biological invasions, the effectiveness of management interventions, and scenarios for the future. The South African situation stands out because of the remarkable diversity of the country, and the wide range of problems encountered in its varied ecosystems, which has resulted in a disproportionate investment into both research and management. The South African experience holds many lessons for other parts of the world, and this book should be of immense value to researchers, students, managers, and policy-makers who deal with biological invasions and ecosystem management and conservation in most other regions

Biological Invasions in South Africa

This open access volume presents a comprehensive account of all aspects of biological invasions in South Africa, where research has been conducted over more than three decades, and where bold initiatives have been implemented in attempts to control invasions and to reduce their ecological, economic and social effects. It covers a broad range of themes, including history, policy development and implementation, the status of invasions of animals and plants in terrestrial, marine and freshwater environments, the development of a robust ecological theory around biological invasions, the effectiveness of management interventions, and scenarios for the future. The South African situation stands out because of the remarkable diversity of the country, and the wide range of problems encountered in its varied ecosystems, which has resulted in a disproportionate investment into both research and management. The South African experience holds many lessons for other parts of the world, and this book should be of immense value to researchers, students, managers, and policy-makers who deal with biological invasions and ecosystem management and conservation in most other regions

Electrical Communication and its Physiological Relevance in Retinal Pigment Epithelium

Verkkokalvon pigmenttiepiteeli (eng. retinal pigment epithelium, RPE) tekee tiivistä yhteistyötä verkkokalvon kanssa turvatakseen näköaistin toiminnan. Useita RPE:n tärkeimpiä tehtäviä, kuten valoa aistivien näköaistinsolujen uusiutumista, säädellään ionikanavien avulla. Näiden kanavien toimintaa ja RPE:n kykyä säädellä kalvopotentiaaliaan ei kuitenkaan vielä täysin ymmärretä. Tässä väitöskirjatyössä tutkittiin jänniteherkkien ionikanavien toimintaa sekä RPE:n sähköistä kytkeytyvyyttä käyttäen mallina ihmisen alkion kantasoluista erilaistettuja RPE-soluja sekä hiiren RPE-kudosta. Jänniteherkät natriumkanavat (NaV) tunnetaan parhaiten osallisuudestaan aktiopotentiaalin synnyssä hermosoluissa, mutta näiden kanavien tiedetään esiintyvän myös useissa muissa solutyypeissä, kuten makrofageissa ja astrosyyteissä, joissa aktiopotentiaaleja ei lähtökohtaisesti muodostu. NaV kanavien ei kuitenkaan uskottu esiintyvän RPE-kudoksessa huolimatta siitä, että niitä on toisinaan havaittu RPE-soluviljelmissä. Tämä väitöskirjatyö osoitti, että sekä kantasoluista erilaistetuissa RPE-soluissa että hiiren RPE-soluissa ilmentyy useita NaV- kanavaperheen alatyyppejä. Samalla havaittiin, että aikaisempi virheellinen johtopäätös aiheutui tutkimusten suorittamisesta yksittäisillä soluilla toiminnallisen kudoksen sijaan. Tässä työssä osoitettiin myös löydettyjen Nav-kanavatyyppien toiminnallisuus sähköfysiologisilla mittauksilla. Merkittävimpien kanavatyyppien (NaV1.4–NaV1.6 sekä NaV1.8) havaittiin sijoittuvan solu-soluliitoksiin tai RPE:n apikaaliselle solukalvolle. RPE-solujen sähköfysiogisia mittauksia on tyypillisesti tehty yksittäisistä eristetyistä soluista. Tästä johtuen RPE-solujen sähköistä kytkeytyvyyttä ei ole selvitetty nisäkkäillä, vaikka tiedetään, että aukkoliitoksilla on tärkeitä tehtäviä silmän kehityksessä. Tämä väitöskirjatyö osoitti, että solujen merkittävin aukkoliitosproteiini (engl. Connexin, Cx) on Cx43, jonka havaittiin muodostavan sekä aukkoliitoksia että puolikkaita hemikanavia solujen apikaalisella pinnalla. Sähköfysiologiset mittaukset osoittivat, että RPE:n laajasta aukkoliitosten verkostosta huolimatta RPE-solujen välinen kytkeytyvyys on suhteellisen alhainen. Kytkeytyvyyttä voitiin kuitenkin säädellä aukkoliitosten farmakologisilla estäjillä, tai estämällä tietyn Cdk5 (engl. cyclin-dependent kinase 5) kinaasi-entsyymin toimintaa. NaV-kanavien ja aukkoliitosten merkitystä RPE:n fysiologiassa tutkittiin keskittymällä näköaistinsolujen kalvojen uusiutumiseen, jossa RPE:n solusyönti eli fagosytoosi on merkittävässä roolissa. Tulokset osoittivat, että fagosytoosin aikana NaV-alatyypit NaV1.4 ja NaV1.8 esiintyvät lähellä näköaistinsolujen kalvopartikkeleita. NaV-kanavien toiminnan estäminen farmakologisesti tai geneettisesti (engl. short hairpin RNA, shRNA) vähensi merkittävästi fagosytoosin tehokkuutta. Lisäksi näiden kanavien havaittiin paikantuvan sekä apikaalipinnalle muodostuviin fagosytoosi-kuppeihin, että jo sisään otettuihin fagosomeihin yhdessä endosomien markkeriproteiinien (engl. rat sarcoma virus-related protein, Rab7) kanssa. Nämä tulokset antavat viitteitä siitä, että NaV-kanavilla olisi monipuolisia tehtäviä fagosytoosin aikana. NaV-kanavien lisäksi myös Cx43:n havaittiin esiintyvän näköaistinsolujen kalvopartikkelien kanssa fagosytoosissa ja tulokset antavat viitteitä siitä, että aukkoliitoksia otetaan solujen sisälle prosessin aikana. Fosforylaation havaittiin säätelevän tätä aukkoliitosten siirtymää ja erityisesti Cdk5-, ja proteiinikinaasi C- entsyymeillä oli merkittävä rooli tässä säätelyssä. Tämän työn tulokset osoittivat, että Cx43 liittyy fagosytoosikuppien muodostukseen sekä solujen aktiini-tukirangan uudelleen järjestymiseen. Fagosytoosin säätelyn tiedetään perustuvan vuorokausirytmiin ja mielenkiintoista on, että Cdk5-kinaasin on osoitettu vaikuttavan tähän rytmiin. On siis mahdollista, että Cdk5 auttaa myös fagosytoosin ajoituksen säätelyssä. Kokonaisuutena työni osoittaa RPE:n fysiologian ja sen ionikanavakoneiston säätelyn monimutkaisuuden. Nav-kanavien roolin on havaittu olevan huomattavasti monipuolisempi kuin aktiopotentiaalien muodostus hermosoluissa ja tuloksemme vahvistavat tätä käsitystä. Yksi työni yllättävimmistä ja merkittävimmistä tuloksista oli, että RPE voi säädellä kalvojännitettään ja epiteelikudoksen solujen välistä viestintäänsä nopeasti. Tarkemmat tiedot tämän ionisignaloinnin roolista fagosytoosissa lisäävät ymmärrystämme prosessista, joka on merkittävä näkökyvyllemme. Yhteenvetona tämä työ osoittaa, että RPE:n rooli yhteistyössä verkkokalvon kanssa on paljon aktiivisempi kuin on aikaisemmin luultu.Retinal pigment epithelium (RPE) is a tissue that preserves the health and functionality of its closely associated neural tissue, the retina. Many of the essential functions of RPE, including the renewal of light-sensing retinal photoreceptors, are regulated by ion channels. Yet, the involved ionic mechanisms, the extent of membrane potential dynamics, and the intercellular communication are not entirely understood. In this thesis, I studied the voltage-gated ion channels and electrical coupling of RPE in both human embryonic stem cell-derived and mouse RPE. Voltage-gated sodium channels (NaV), while best known for their role in action potential generation, are expressed in several non-excitable cell types such as macrophages and astrocytes. Yet, these channels had not been considered to exist in native RPE, although they had occasionally been detected in cell culture. This thesis demonstrates that stem cell-derived and mouse RPE exhibit several subtypes of NaV channels and that their earlier dismissal was due to cell isolation procedures. Our electrophysiological recordings showed that these identified NaV channels are functional. The main channel subtypes NaV1.4–NaV1.6 and NaV1.8 were found to localize in the cell-cell junctions or apical membrane in RPE. As the conventional method to carry out electrophysiological recordings in RPE is to use single cells, the electrical connectivity had not been characterized in mammalian RPE, despite the importance of gap junctions in ocular development. In this thesis, we showed that the major connexin (Cx) isoform was Cx43 which was found to form both gap junctions and apical hemichannels. The electrophysiological recordings demonstrated that the electrical connectivity was relatively low despite the extensive network of gap junctions in RPE. Yet, it was modifiable by gap junction blockers or by inhibiting a specific kinase known as cyclin-dependent kinase 5 (Cdk5). The significance of NaV channels and gap junctions to RPE physiology was investigated by focusing on the renewal of photoreceptor outer segments, where phagocytosis by RPE plays a key role. The results demonstrated that NaV subtypes NaV1.4 and NaV1.8 localize with the outer segments during phagocytosis. Moreover, inhibiting the activity of NaV channels with pharmacological modulators or short hairpin RNA (shRNA) significantly impaired phagocytosis efficiency. Furthermore, Nav channels were found to localize to the forming phagocytic cups in the apical membrane and the ingested phagosomes together with an endosomal marker Rab7. The results obtained in this thesis imply that NaV channels have versatile roles in phagocytosis. In addition to NaV channels, Cx43 localized adjacent to outer segments during phagocytosis, and the results indicate that gap junctions are internalized during the process. This translocation of gap junctions was shown to be regulated by phosphorylation, particularly by kinases such as Cdk5 and protein kinase C. The results obtained in this thesis imply that Cx43 is involved in the formation of phagocytic cups. As phagocytosis is known to be under circadian control, and Cdk5 has previously been shown to regulate this cycle, it is plausible that Cdk5 helps to control the rhythm of photoreceptor renewal. Our results highlight the complexity of RPE physiology and its ion channel machinery. The findings add to the growing body of evidence demonstrating that NaV channels' role is much more diverse than action potential generation. The results show that RPE can generate fast changes in voltage and rapidly modify its cell-cell connectivity across the epithelium. Gaining a deeper understanding of the involvement of ionic mechanisms in phagocytosis could help us to understand the phagocytosis pathway both in the healthy and diseased eye. Ultimately, this work highlights that RPE's role in its interaction with the neural retina is far more active than was previously thought