Dry spell mitigation to upgrade semi-arid rainfed agriculture : Water harvesting and soil nutrient management for smallholder maize cultivation in Machakos, Kenya

Improvements in on-farm water and soil fertility management through water harvesting may prove key to up-grade smallholder farming systems in dry sub-humid and semi-arid sub-Sahara Africa (SSA). The currently experienced yield levels are usually less than 1 t ha-1, i.e., 3-5 times lower than potential levels obtained by commercial farmers and researchers for similar agro-hydrological conditions. The low yield levels are ascribed to the poor crop water availability due to variable rainfall, losses in on-farm water balance and inherently low soil nutrient levels. To meet an increased food demand with less use of water and land in the region, requires farming systems that provide more yields per water unit and/or land area in the future. This thesis presents the results of a project on water harvesting system aiming to upgrade currently practised water management for maize (Zea mays, L.) in semi-arid SSA. The objectives were to a) quantify dry spell occurrence and potential impact in currently practised small-holder grain production systems, b) test agro-hydrological viability and compare maize yields in an on-farm experiment using combinations supplemental irrigation (SI) and fertilizers for maize, and c) estimate long-term changes in water balance and grain yields of a system with SI compared to farmers currently practised in-situ water harvesting. Water balance changes and crop growth were simulated in a 20-year perspective with models MAIZE1&2. Dry spell analyses showed that potentially yield-limiting dry spells occur at least 75% of seasons for 2 locations in semi-arid East Africa during a 20-year period. Dry spell occurrence was more frequent for crop cultivated on soil with low water-holding capacity than on high water-holding capacity. The analysis indicated large on-farm water losses as deep percolation and run-off during seasons despite seasonal crop water deficits. An on-farm experiment was set up during 1998-2001 in Machakos district, semi-arid Kenya. Surface run-off was collected and stored in a 300m3 earth dam. Gravity-fed supplemental irrigation was carried out to a maize field downstream of the dam. Combinations of no irrigation (NI), SI and 3 levels of N fertilizers (0, 30, 80 kg N ha-1) were applied. Over 5 seasons with rainfall ranging from 200 to 550 mm, the crop with SI and low nitrogen fertilizer gave 40% higher yields (**) than the farmers’ conventional in-situ water harvesting system. Adding only SI or only low nitrogen did not result in significantly different yields. Accounting for actual ability of a storage system and SI to mitigate dry spells, it was estimated that a farmer would make economic returns (after deduction of household consumption) between year 2-7 after investment in dam construction depending on dam sealant and labour cost used. Simulating maize growth and site water balance in a system of maize with SI increased annual grain yield with 35 % as a result of timely applications of SI. Field water balance changes in actual evapotranspiration (ETa) and deep percolation were insignificant with SI, although the absolute amount of ETa increased with 30 mm y-1 for crop with SI compared to NI. The dam water balance showed 30% productive outtake as SI of harvested water. Large losses due to seepage and spill-flow occurred from the dam. Water productivity (WP, of ETa) for maize with SI was on average 1 796 m3 per ton grain, and for maize without SI 2 254 m3 per ton grain, i.e, a decerase of WP with 25%. The water harvesting system for supplemental irrigation of maize was shown to be both biophysically and economically viable. However, adoption by farmers will depend on other factors, including investment capacity, know-how and legislative possibilities. Viability of increased water harvesting implementation in a catchment scale needs to be assessed so that other down-stream uses of water remains uncompromised.

Second law analysis and simulation techniques for the energy optimization of buildings

The research activity described in this thesis is focused mainly on the study of finite-element techniques applied to thermo-fluid dynamic problems of plant components and on the study of dynamic simulation techniques applied to integrated building design in order to enhance the energy performance of the building. The first part of this doctorate thesis is a broad dissertation on second law analysis of thermodynamic processes with the purpose of including the issue of the energy efficiency of buildings within a wider cultural context which is usually not considered by professionals in the energy sector. In particular, the first chapter includes, a rigorous scheme for the deduction of the expressions for molar exergy and molar flow exergy of pure chemical fuels. The study shows that molar exergy and molar flow exergy coincide when the temperature and pressure of the fuel are equal to those of the environment in which the combustion reaction takes place. A simple method to determine the Gibbs free energy for non-standard values of the temperature and pressure of the environment is then clarified. For hydrogen, carbon dioxide, and several hydrocarbons, the dependence of the molar exergy on the temperature and relative humidity of the environment is reported, together with an evaluation of molar exergy and molar flow exergy when the temperature and pressure of the fuel are different from those of the environment. As an application of second law analysis, a comparison of the thermodynamic efficiency of a condensing boiler and of a heat pump is also reported. The second chapter presents a study of borehole heat exchangers, that is, a polyethylene piping network buried in the soil which allows a ground-coupled heat pump to exchange heat with the ground. After a brief overview of low-enthalpy geothermal plants, an apparatus designed and assembled by the author to carry out thermal response tests is presented. Data obtained by means of in situ thermal response tests are reported and evaluated by means of a finite-element simulation method, implemented through the software package COMSOL Multyphysics. The simulation method allows the determination of the precise value of the effective thermal properties of the ground and of the grout, which are essential for the design of borehole heat exchangers. In addition to the study of a single plant component, namely the borehole heat exchanger, in the third chapter is presented a thorough process for the plant design of a zero carbon building complex. The plant is composed of: 1) a ground-coupled heat pump system for space heating and cooling, with electricity supplied by photovoltaic solar collectors; 2) air dehumidifiers; 3) thermal solar collectors to match 70% of domestic hot water energy use, and a wood pellet boiler for the remaining domestic hot water energy use and for exceptional winter peaks. This chapter includes the design methodology adopted: 1) dynamic simulation of the building complex with the software package TRNSYS for evaluating the energy requirements of the building complex; 2) ground-coupled heat pumps modelled by means of TRNSYS; and 3) evaluation of the total length of the borehole heat exchanger by an iterative method developed by the author. An economic feasibility and an exergy analysis of the proposed plant, compared with two other plants, are reported. The exergy analysis was performed by considering the embodied energy of the components of each plant and the exergy loss during the functioning of the plants.

Reciproche influenze tra geomorfologia e popolamento antico presso le piane di foce dei fiumi tirrenici. Il caso del Fiume Garigliano

La Piana di foce del Garigliano (al confine tra Lazio e Campania) è caratterizzata, fino ad epoche recenti, dalla presenza di aree palustri e umide. Lo studio in corso cerca di ricostruire l’evoluzione dell’ambiente costiero mettendolo in relazione alla presenza dell’uomo, alla gestione del territorio, alle vicende storiche e alle variazioni climatiche utilizzando molteplici metodologie tipiche della geoarcheologia. Si tratta di un approccio multidisciplinare che cerca di mettere insieme analisi tipiche dell’archeologia, della topografia antica, della geomorfologia, della geologia e della paleobotanica. Fino all’età del Ferro l’unica traccia di popolamento viene da Monte d’Argento, uno sperone roccioso isolato lungo la costa, posto al limite occidentale di un ambiente sottostante che sembra una palude chiusa e isolata da apporti sedimentari esterni. Con il passaggio all’età del ferro si verifica un mutamento ambientale con la fine della grande palude e la formazione di una piccola laguna parzialmente comunicante con il mare. L’arrivo dei romani alla fine del III secolo a.C. segna la scomparsa dei grandi centri degli Aurunci e la deduzione di tre colonie (Sessa Aurunca, Sinuessa, Minturno). Le attività di sistemazione territoriale non riguardarono però le aree umide costiere, che non vennero bonificate o utilizzate per scopi agricoli, ma mantennero la loro natura di piccoli laghi costieri. Quest’epoca è dunque caratterizzata da una diffusione capillare di insediamenti, basati su piccole fattorie o installazioni legate allo sfruttamento agricolo. Poche sono le aree archeologiche che hanno restituito materiali successivi al II-III secolo d.C. La città resta comunque abitata fino al VI-VII secolo, quando l’instabilità politica e l’impaludamento dovettero rendere la zona non troppo sicura favorendo uno spostamento verso le zone collinari. Un insediamento medievale è attestato solo a Monte d’Argento e una frequentazione saracena dell’inizio del IX secolo è riportata dalle fonti letterarie, ma non vi è ancora nessuna documentazione archeologica.

Certificates for Incremental Type Checking

The central topic of this thesis is the study of algorithms for type checking, both from the programming language and from the proof-theoretic point of view. A type checking algorithm takes a program or a proof, represented as a syntactical object, and checks its validity with respect to a specification or a statement. It is a central piece of compilers and proof assistants. We postulate that since type checkers are at the interface between proof theory and program theory, their study can let these two fields mutually enrich each other. We argue by two main instances: first, starting from the problem of proof reuse, we develop an incremental type checker; secondly, starting from a type checking program, we evidence a novel correspondence between natural deduction and the sequent calculus.

Extending Implicit Computational Complexity and Abstract Machines to Languages with Control

The Curry-Howard isomorphism is the idea that proofs in natural deduction can be put in correspondence with lambda terms in such a way that this correspondence is preserved by normalization. The concept can be extended from Intuitionistic Logic to other systems, such as Linear Logic. One of the nice conseguences of this isomorphism is that we can reason about functional programs with formal tools which are typical of proof systems: such analysis can also include quantitative qualities of programs, such as the number of steps it takes to terminate. Another is the possiblity to describe the execution of these programs in terms of abstract machines. In 1990 Griffin proved that the correspondence can be extended to Classical Logic and control operators. That is, Classical Logic adds the possiblity to manipulate continuations. In this thesis we see how the things we described above work in this larger context.

Il diritto alla detrazione e le frodi Iva

Il presente lavoro parte dalla constatazione che l’Imposta sul valore aggiunto è stata introdotta con lo scopo specifico di tassare il consumo in modo uniforme a livello europeo. La globalizzazione dell’economia con l’abolizione delle frontiere ha tuttavia favorito la nascita non solo di un mercato unico europeo, ma anche di “un mercato unico delle frodi”. L’esistenza di abusi e frodi in ambito Iva risulta doppiamente dannosa per l’Unione europea: tali condotte incidono quantitativamente sull'ammontare delle risorse proprie dell’Unione e sulle entrate fiscali dei singoli Stati membri nonché violano il principio di concorrenza e producono distorsioni nel mercato unico. È in questo contesto che intervengono i giudici nazionali e la Corte di Giustizia, al fine di porre un freno a tali fenomeni patologici. Quest’ultima, chiamata a far rispettare il diritto comunitario, ha sviluppato una misura antifrode e antiabuso consistente nel diniego del diritto alla detrazione qualora lo stesso venga invocato dal soggetto passivo abusivamente o fraudolentemente. Vedremo però che il problema non può essere facilmente ridotto a formule operative: al di là dello schema, fin troppo scontato, dell’operatore apertamente disonesto e degli operatori con esso dichiaratamente correi, rimane il territorio grigio dei soggetti coinvolti, qualche volta inconsapevolmente qualche volta consapevolmente, ma senza concreta partecipazione nella frode da altri orchestrata. Permane a questo punto la domanda se sia coerente - in un sistema impositivo che privilegia i profili oggettivi, prescindendo, salvo gli aspetti sanzionatori, da quelli soggettivi- negare il diritto alla detrazione Iva per asserita consapevolezza di comportamenti fraudolenti altrui o se non vi siano regole più adatte al fine di porre un freno alle frodi e dunque più conformi al principio di proporzionalità.

El principio de neutralidad interna en el IVA

La tesis estudia el principio de neutralidad en su vertiente interna y su aplicación efectiva en el IVA. Se centra en los principales aspectos de la configuración jurídica del impuesto: derecho de deducción, exenciones y tipos reducidos. Se realiza en primer lugar una aproximación teórica al principio desde un punto de vista jurídico y también económico. Una vez construido el principio se acomete una comparación de las distintas clases de impuestos indirectos que pueden establecerse y se analiza su cumplimiento del principio de neutralidad fiscal. El énfasis es mayor en los impuestos en cascada, impuestos monofásicos minoristas y en el IVA. El objetivo de la tesis es, por tanto, concretar el contenido del principio, desarrollar sus implicaciones económicas principales y analizar el grado de cumplimiento real de la Directiva IVA. Desde el punto de vista del derecho de deducción y de las exenciones el estudio se apoya en el análisis de la jurisprudencia del Tribunal de Justicia de la Unión Europea, donde se profundizará en cuestiones como la utilización de bienes de uso mixto, la consideración de costes como directos o generales y las formas de ejercicio del exceso de deducción (devolución y compensación). Además, la tesis muestra las principales excepciones al principio de neutralidad establecidas en la Directiva IVA: prohibiciones al derecho de deducción, exenciones y tipos reducidos. En esta parte también se apoyará el estudio en la jurisprudencia del TJUE, que ha construido en gran medida los criterios de interpretación de estas excepciones. En conclusión, el objetivo de la tesis es medir si la directiva IVA cumple con el principio de neutralidad fiscal, para lo que deberá haberse especificado primero su significado concreto y se habrá debido diferenciar entre sus dos dimensiones: interna y externa.

Keplero e la musica. Il Libro III dell'Harmonice mundi (Linz, 1619): traduzione e Introduzione

Questo lavoro si concentra su un particolare aspetto della sfaccettata ricerca scientifica di Johannes Kepler (1571-1630), ossia quello teorico-musicale. I pensieri dell’astronomo tedesco riguardanti tale campo sono concentrati – oltre che in alcuni capitoli del Mysterium cosmographicum (1596) ed in alcune sue lettere – nel Libro III dell’Harmonices mundi libri quinque (1619), che, per la sua posizione mediana all’interno dell’opera, tra i primi due libri geometrici e gli ultimi due astronomici, e per la sua funzione di raccordo tra la «speculazione astratta» della geometria e la concretizzazione degli archetipi geometrici nel mondo fisico, assume la struttura di un vero e proprio trattato musicale sul modello di quelli rinascimentali, nel quale la «musica speculativa», dedicata alla teoria delle consonanze e alla loro deduzione geometrica precede la «musica activa», dedicata alla pratica del canto dell’uomo nelle sue differenze, generi e modi. La tesi contiene la traduzione italiana, con testo latino a fronte, del Libro III dell’Harmonice, e un’ampia introduzione che percorre le tappe fondamentali del percorso biografico e scientifico che hanno portato alla concezione di quest’opera – soffermandosi in particolare sulla formazione musicale ricevuta da Keplero, sulle pagine di argomento musicale del Mysterium e delle lettere, e sulle riflessioni filosofico-armoniche sviluppate negli anni di ricerca – e offre gli elementi fondamentali per poter comprendere l’Harmonice mundi in generale e il Libro III in particolare. A ciò si aggiunge, in Appendice, la traduzione, anch’essa con testo latino a fronte, della Sectio V, dedicata alla musica, del Liber IX dell’Almagestum novum (1651) di Giovanni Battista Riccioli (1598-1671), interessante sia dal punto di vista della recezione delle teorie di Keplero che dal punto di vista della storia delle idee musicali.

Isolierung, Charakterisierung und Nachweis methanogener Archaea aus laufenden Praxis-NawaRo-Biogasanlagen unter besonderer Beruecksichtigung der Gattung Methanobacterium

Im Verlauf der Forschungsarbeit wurden Proben aus fünf, mit nachwachsenden Rohstoffen (NawaRo) beschickten, landwirtschaftlichen Biogasanlagen (BGA) auf die Biozönose methanogener Archaea hin molekularbiologisch untersucht. Über „amplified rDNA restriction analysis“-Screening (ARDRA) von Bibliotheken auf Basis von 16S rRNA-Genfragmenten konnte anhand zweier beispielhafter BGA das Vorkommen von Vertretern der Gattungen Methanoculleus (Mcu.), Methanobacterium (Mb.), Methanosarcina (Msc.) und Methanosaeta (Mst.) nachgewiesen werden. Mittels denaturierender Gradienten-Gelelektrophorese (DGGE) wurde das Vorkommen dieser Mikroorganismen auch in den übrigen Anlagen gezeigt. Ergänzend dazu wurde in drei Anlagen Methanospirillum hungatei nachgewiesen. Nach Ausarbeitung gattungsspezifischer Isolierungsstrategien konnten insgesamt zehn Vertreter der Gattung Methanobacterium (Isolate Mb1 bis Mb10) und jeweils ein Vertreter der Gattungen Methanoculleus (Isolat Mcu(1)), Methanosarcina (Isolat NieKK) und Methanosaeta (Isolat Mst1.3) aus den BGA-Proben isoliert werden. Durch in silico-Abgleich der partiellen 16S rRNA-Gensequenzen wurden diese als Verwandte von Mb. formicicum MFT, Mcu. bourgensis MS2T, Msc. mazei S-6T und Mst. concilii FE mit einer Sequenzidentität > 97% identifiziert. Im Laufe weiterer molekularbiologischer Untersuchungen mittels DGGE und ARDRA-Analyse konnten die Isolate den Referenzstämmen zugeordnet werden. In Bezug auf die Gattung Methanobacterium ergaben sich jedoch leichte Abweichungen. Diese bestätigten sich in vergleichenden Analysen des genomischen Fingerabdrucks in der „specifically amplified polymorphic DNA“-PCR (SAPD-PCR), welche im Rahmen dieser Arbeit erstmalig erfolgreich auf archaeelle Organismen angewandt wurde. Hier zeigten die Isolate zwei von den Fingerabdrücken der untersuchten Referenzstämme verschiedene Hauptamplifikationsmuster. Aufgrund der Vielzahl der Isolate sowie dem signifikanten Vorkommen in qPCR-Analysen und Klonbibliotheken fokussierten sich die weiteren Arbeiten zur genauen Untersuchung dieser Abweichungen auf phylogenetische Analysen der Gattung Methanobacterium und die Entwicklung von Nachweissystemen. Die Aufklärung eines Großteils der 23S rRNA-Gensequenzen der Isolate und von ausgewählten Typstämmen ermöglichte ergänzende phylogenetische Untersuchungen zu durchgeführten 16S rRNA-Analysen. Dabei wurden die Isolate jeweils in einem eigenen Cluster abseits der meisten Referenzstämme aus der Gattung Methanobacterium positioniert. Analog zur Musterbildung im Rahmen der SAPD-Analyse zeigte sich eine Differenzierung in zwei Äste und ergab in Übereinstimmung mit den in silico-Sequenzabgleichen den höchsten Verwandtschaftsgrad mit Mb. formicicum MFT. Die Eignung der SAPD-PCR zur Ableitung spezifischer Primerpaare konnte erstmals auch für methanogene Archaea gezeigt werden. Die Ableitung zweier Primerpaare mit Spezifität für die Methanobacterium-Isolate Mb1 bis Mb10 sowie für den Typstamm Mb. formicicum MFT gelang und konnte im Rahmen eines Direkt-PCR-Nachweises erfolgreich auf Reinkulturen und Fermenterproben angewandt werden. Unter Einbezug der sequenzierten 23S rRNA-Genfragmente gelang die Erstellung von Oligonukleotid-Sonden für den Einsatz in Fluoreszenz in situ-Hybridisierungsexperimenten. Im Praxistest ergab sich für diese Sonden eine Spezifität für alle getesteten Vertreter der Gattung Methanobacterium sowie für Methanosphaera stadtmanae MCB-3T und Methanobrevibacter smithii PST.rnSomit konnten im Laufe der Arbeit die dominanten methanogenen Archaea in NawaRo-BGA in mehrphasigen Experimenten nachgewiesen, quantifiziert und auf nur wenige Gattungen eingegrenzt werden. Vertreter der vier dominanten Gattungen wurden isoliert und Nachweissysteme für Arten der Gattung Methanobacterium erstellt.rn

The Telescope Stand Inspiration for Marcel Duchamp’s Bicycle Wheel Readymade

This article is the result of research following on from the author’s previous article on the same subject, ›The Inspiration for Marcel Duchamp’s Bicycle Wheel Readymade‹ written in 2007. In that article the author argued by process of deduction that Duchamp’s Bicycle Wheel was inspired by an improvised telescope stand and was not the product of the artist’s imagination as the artist claimed. This article presents new supporting evidence of a Great War period photograph of an improvised telescope stand made with a bicycle wheel and forks. This article also examines the dating of the first version and construction of the authorised versions of Bicycle Wheel and presents new evidence for the source of the forks component of the 1916 version.

Wissenschaftliche Validität als Qualitätsmerkmal der Zukunftsforschung

Zukunftsforschung beansprucht, wissenschaftlichen Kriterien zu genügen. Anders als in anderen Disziplinen trifft man jedoch in diesem Fachgebiet auf besondere Herausforderungen hinsichtlich der Kriterien wissenschaftlicher Validität und an die Verfahren ihrer Prüfung, da übliche Ansätze wie die empirische Bewährung oder logische Ableitung in der Zukunftsforschung nicht anwendbar sind. Stattdessen können, so die hier vertretene These, strukturelle Überlegungen aus der Kohärenztheorie der Wahrheit übertragen werden, um die wissenschaftliche Qualität von Zukunftsaussagen konzeptuell zu begreifen und mit Kriterien zur Validierung zu operationalisieren. Entscheidend ist, dass Aussagen der Zukunftsforschung transparent in ihre Bestandteile zerlegt werden und dass sowohl für die Bestandteile als auch für die Art und Weise der Zusammenfügung der Bestandteile belastbare Argumente angeführt werden können. Der Beitrag schließt mit Überlegungen, was von einer explizit wissenschaftlichen Validierung von Zukunftsüberlegungen erwartet werden kann und was nicht.

Finale Fixationen, sportmotorische Leistung und eine Inhibitionshypothese. Mechanismen des "Quiet Eye"

Vielfach konnte in den letzten Jahren die Bedeutung einer langen letzten Fixation vor Bewegungsbeginn – des sogenannten "Quiet Eye" – für die sportmotorische Leistung aufgezeigt werden. Obgleich dieses Phänomens breit untersucht wurde, mangelt es bislang an einer zufriedenstellenden Erklärung. In diesem Beitrag werden daher aktuelle Erklärungsversuche diskutiert. Es zeigt sich, dass vorliegende Beiträge aus der Kognitions- und der ökologischen Psychologie konzeptuelle oder methodische Mängel aufweisen. Aus diesen Gründen wird – zunächst für Aufgaben mit hohen Präzisionsanforderungen – ein Inhibitionsmechanismus zur Erklärung des Quiet-Eye-Phänomens vorgeschlagen mit der zentralen Aussage, dass die Verarbeitung leistungsrelevanter Hinweisreize durch ein "ruhiges Auge" von Störungen abgeschirmt wird. Abschließend kann gezeigt werden, dass sich der vorgeschlagene Mechanismus mit der bestehenden Befundlage als kompatibel erweist und er die Ableitung weitergehender Vorhersagen erlaubt.

Herbrand Theorems for Substructural Logics

Herbrand and Skolemization theorems are obtained for a broad family of first-order substructural logics. These logics typically lack equivalent prenex forms, a deduction theorem, and reductions of semantic consequence to satisfiability. The Herbrand and Skolemization theorems therefore take various forms, applying either to the left or right of the consequence relation, and to restricted classes of formulas.

Índices de calidad de sitio de Populus nigra ‘Italica’ en plantaciones lineales en el noroeste de Chubut

En el noroeste del Chubut, los álamos se encuentran establecidos en cortinas de protección en predios de pastoreo o donde se cultivan pasturas y forrajes en secano. El Populus nigra ‘Italica’ es el clon más difundido en plantaciones lineales, ubicadas en diferentes calidades de sitio. No existen antecedentes sobre crecimiento en altura e Índice de Sitio en la zona. Se seleccionaron ocho sitios de muestreo, donde fueron apeados 24 árboles dominantes, a los que se les realizó análisis fustal. Con los pares de datos de edad-altura, resultantes del análisis de fuste de los árboles muestra, se ajustó el modelo de Chapman-Richards mediante técnicas de regresión no lineal. Se construyó una familia de curvas de crecimiento en altura, según la metodología de curva guía. Las curvas de Índice de Sitio, basadas en altura y edad, se construyeron mediante deducción matemática a partir de la función de crecimiento en altura, tomándose como edad de referencia 25 años a la altura del pecho. Se definieron cinco calidades de sitio, con un rango de 4 metros, con Índices de Sitio comprendidos entre 19 y 35 m.