Understanding the adoption of systemic innovations in smallholder agriculture: the System of Rice Intensification (SRI) in Timor Leste

Crop Production/Industries, Farm Management,

Extending removal and distance-removal models for abundance estimation by modeling detections in continuous time

In this disseration, we estimate abundance from removal-sampled animal wildlife point-count surveys, focusing on models to account for heterogeneous detection probabilities. In contrast to many published models, our research treats individual times to detection as continuous-time responses. Adopting this method enables us to ask questions that are impractical under existing discrete-time models. We accomplish our analyses by using a parametric survival analysis approach within the N-mixture class of hierarchical animal abundance models. In Chapter 2, we construct models for removal-sampled data that allow detection rates to change systematically over the course of each observation period. Most studies assume detection rates are constant, but our analysis demonstrates this assumption to be very informative, leading to biased and overly precise estimates. Non-constant models prove less biased with better coverage statistics over a range of simulated datasets. In Chapter 3, we extend the continuous-time modeling approach to distance-removal sampled surveys. We introduce a new model that successfully integrates two subtly different existing mechanisms for modeling distance-removal surveys: one that focuses on detecting available individuals and one that focuses on detecting availability cues (e.g. bird calls). We articulate the distinctions between the two and place them within current terminology for availability and perceptibility. Our new model accurately estimates abundance and detection from datasets simulated via either mechanism, but models that assume only one mechanism are often not robust to misspecification. In Chapter 4, we apply our model from Chapter 3 to six avian species monitored in removal- and distance-sampled point-count surveys in Iowa agricultural fields. We articulate several ways in which the model does not match data characteristics, and we identify priorities for developing this model in order to make it more flexible and feasible

From Molecular Parameters to Electronic Properties of Organic Thin Films: A Photoelectron Spectroscopy Study

The field of organic semiconductors considerably gained research interest due to promising applications in flexible, large-area, lightweight and semitransparent electronic devices, such as light-emitting diodes, solar cells, or transistors. The working mechanism of such devices depends on the combination of different neat or blended organic films, whose physical properties substantially differ from those of inorganic semiconductors. Weak intermolecular electronic coupling and large energetic disorder result in a thermally activated charge carrier hopping between localized electronic states. Therefore, many processes in organic devices are determined by properties of single molecules. The major goal of this thesis is to disclose relationships between electronic properties of organic thin films and molecular parameters, helping to provide specific design rules for new molecules. In the first part of this thesis, the impact of molecular quadrupole moments on the transport energies of charge carriers is investigated by photoelectron spectroscopy. The results reveal for a variety of planar small molecules that charge-quadrupole interactions along the pi-pi-stacking geometry induce large energy changes with molecular orientation at surfaces and interfaces of crystalline films. Furthermore, these electrostatic interactions enable a continuous tuning of energy levels in crystalline intermixed blends by more than 1 eV. In blends exhibiting separated phases, quadrupole moments induce electrostatic gradients from the interface to the bulk phase. These two effects are exploited in organic solar cells consisting of a ternary blend of two intermixed donors blended with one acceptor. By changing the mixing ratio of the two donors, the open-circuit voltage can be continuously tuned. Additionally, the dissociation barrier of electron-hole pairs at the interface can be varied, reflecting in a change in photocurrent. In the second part, molecular n-doping is investigated, facing the particular issue of air sensitivity. The analysis of two air stable precursor molecules of n-dopants reveals very good doping properties after their thermal evaporation, partly even better than for a reference air sensitive dopant. For high doping concentrations, temperature-dependent conductivity measurements show that the thermal activation energy of many compounds can be described by an empirical function of two molecular parameters, the relaxation energy of matrix anions and the Coulomb binding energy of integer charge transfer complexes (ICTCs) between matrix anions and dopant cations. The investigation of the density of states indicates that charge transport at high doping concentrations predominantly occurs by a rearrangement between different ICTC configurations and is limited by their energetic disorder, which can be reduced substantially by adding electron withdrawing side groups to the matrix molecules. The exposure of several n-doped semiconductors to air reveals that the air stability increases with larger ionization energies of ICTCs. This effect is attributed to an universal trap introduced upon air exposure. Its energy is estimated to be 3.9 eV, setting a general limit for air stable n-doping.Organische Halbleiter bieten vielversprechende Anwendungsmöglichkeiten in ultraleichten, flexiblen, großflächigen und semitransparenten elektronischen Bauteilen wie beispielsweise in Leuchtdioden, Solarzellen oder Transistoren. Die Funktionsweise solcher Bauteile basiert auf der Kombination verschiedener organischer Moleküle in dünnen Schichten, deren physikalische Eigenschaften sich stark von herkömmlichen anorganischen Halbleitern unterscheiden. Die schwache elektronische Kopplung zwischen einzelnen Molekülen und die große energetische Unordnung in organischen Halbleitern bewirken einen temperaturaktivierten Transport von Ladungsträgern zwischen lokalisierten elektronischen Zuständen. Daher werden viele Prozesse in organischen Halbleiterbauelementen von molekularen Eigenschaften bestimmt. Das Hauptziel dieser Dissertation ist es, verschiedene elektronische Eigenschaften dünner organischer Filme mit molekularen Parametern in Verbindung zu bringen, was als Grundlage für die gezielte Entwicklung neuer Moleküle dienen soll. Im ersten Teil dieser Arbeit wird mittels Photoelektronenspektroskopie der Einfluss molekularer Quadrupolmomente auf die Transportenergien von Ladungsträgern untersucht. Für eine große Anzahl verschiedener planarer Moleküle zeigt sich, dass die Wechselwirkung von Ladungen mit Quadrupolmomenten entlang der pi-pi-Stapelrichtung große Veränderungen der Energieniveaus an der Oberfläche und der Grenzfläche von kristallinen Filmen bewirkt, beispielsweise wenn sich die Molekülorientierung ändert. Dieser elektrostatische Effekt ermöglicht es, die Energieniveaus in einer homogen durchmischten Schicht zweier Molekülarten kontinuierlich über eine Größenordnung von mehr als 1 eV durchzustimmen. In Mischungen mit einer Phasentrennung können molekulare Quadrupolmomente einen elektrostatischen Gradienten an der Grenzfläche zwischen den Phasen ausbilden. Diese beiden Effekte werden in Solarzellen ausgenutzt, die aus einer Mischung von zwei Donatormolekülen und einem Akzeptormolekül bestehen. Durch Variation des Mischverhältnisses der zwei Donatoren lässt sich die Leerlaufspannung kontunierlich anpassen. Zusätzlich lässt sich die Energiebarriere für die Ladungsträgertrennung an der Grenzfläche reduzieren, was zu einem höheren Photostrom führt. Im zweiten Teil wird molekulare n-Dotierung untersucht, bei der das spezielle Problem der Luftsensitivität berücksichtigt werden muss. Zwei luftstabile Ausgangsmoleküle von n-Dotanden weisen nach ihrer thermischen Verdampfung sehr gute Dotiereigenschaften auf, welche für ein Molekül sogar besser als bei entsprechenden luftsensitiven Referenzdotanden sind. Temperaturabhängige Leitfähigkeitsmessungen zeigen, dass die thermische Aktivierungsenergie bei hohen Dotierkonzentrationen durch eine empirische Funktion von zwei molekularen Parametern beschrieben werden kann, welche die Relaxationsenergie von Anionen des Matrixmoleküls und die Coulombbindungsenergie des Ionenpaars aus Matrix- und Dotandenmolekül sind. Die Untersuchung der Zustandsdichte dieser hochdotierten Halbleiter deutet darauf hin, dass sich der Ladungstransport durch eine Umbesetzung dieser Ionenpaare beschreiben lässt. Der Transport ist dabei durch die energetische Unordnung der Ionenpaare limitiert, welche sich allerdings durch das Hinzufügen von elektronenziehenden Seitengruppen an die Matrixmoleküle deutlich reduzieren lässt. Der Kontakt verschiedener n-dotierter Halbleiter mit Luft zeigt, dass sich die Luftstabilität dieser mit größerer Ionisationsenergie der Anionen des Matrixmaterials verbessert. Diese Beobachtung wird dadurch erklärt, dass durch den Kontakt mit Luft ein universeller Fallenzustand mit der Energie von 3.9 eV entsteht. Dieser setzt eine allgemeine Grenze für luftstabile n-Dotierung

Assessing the Impacts of Time-to-Detection Distribution Assumptions on Detection Probability Estimation

Abundance estimates from animal point-count surveys require accurate estimates of detection probabilities. The standard model for estimating detection from removal-sampled point-count surveys assumes that organisms at a survey site are detected at a constant rate; however, this assumption can often lead to biased estimates. We consider a class of N-mixture models that allows for detection heterogeneity over time through a flexibly defined time-to-detection distribution (TTDD) and allows for fixed and random effects for both abundance and detection. Our model is thus a combination of survival time-to-event analysis with unknown-N, unknown-p abundance estimation. We specifically explore two-parameter families of TTDDs, e.g., gamma, that can additionally include a mixture component to model increased probability of detection in the initial observation period. Based on simulation analyses, we find that modeling a TTDD by using a two-parameter family is necessary when data have a chance of arising from a distribution of this nature. In addition, models with a mixture component can outperform non-mixture models even when the truth is non-mixture. Finally, we analyze an Ovenbird data set from the Chippewa National Forest using mixed effect models for both abundance and detection. We demonstrate that the effects of explanatory variables on abundance and detection are consistent across mixture TTDDs but that flexible TTDDs result in lower estimated probabilities of detection and therefore higher estimates of abundance

Lead Poisoning in Bald Eagles Admitted to Wildlife Rehabilitation Facilities in Iowa, 2004–2014

Eleven years (2004–2014) of bald eagle Haliaeetus leucocephalus data from four independent, state and federally permitted wildlife rehabilitators in Iowa were assessed for the prevalence of elevated lead levels in blood or tissue samples. The relationship between blood lead concentrations and recorded information (age, season, radiographs, and clinical outcome) was investigated. Adult birds had higher blood lead concentrations than immature and juvenile birds. Highest blood lead levels were found during October–January. Bald eagles with positive radiographs for metallic opacities in the digestive tract had higher blood and tissue lead concentrations than those with negative results or those on which no radiograph was performed. Metallic opacities were identified through necropsy. Bald eagles with elevated levels of lead were associated with poor clinical outcomes, indicating that blood lead concentrations could be used as a predictor of clinical outcome

Transparent model concrete with tunable rheology for investigating flow and particle-migration during transport in pipes

The article describes the adaption and properties of a model concrete for detailed flow studies. To adapt the yield stress and plastic viscosity of the model concrete to the corresponding rheological properties of real concrete, the model concrete is made of a mixture of glass beads and a non-Newtonian fluid. The refractive index of the non-Newtonian fluid is adjusted to the refractive index of the glass beads by the addition of a further constituent. The rheological properties of the model concrete are characterised by measurements in concrete rheometers. Finally, the first exemplary results from experiments with the model concrete are presented, which give incipient impressions of the complex internal dynamics in flowing concrete

Extramurale Behandlung und Betreuung von Sexualstraftätern: Ergebnisse einer bundesweiten Umfrage zur Nachsorge-Praxis 2016

Aufgrund aktueller gesetzlicher Bestimmungen wird die Mehrheit der entlassenen Sexualstraftäter in Deutschland nach ihrer Entlassung ambulant nachversorgt. In dem vorliegenden Band werden Daten von insgesamt 47 Einrichtungen, die Bestandteil dieser extramuralen Versorgungsstruktur sind, vorgestellt und diskutiert. Die an der Untersuchung teilnehmenden Institutionen werden mehrheitlich durch das Justizministerium bzw. justiznahe Behörden finanziert. Zwei Drittel der Gesamtklientel sind Sexualstraftäter, die sich größtenteils unter Führungsaufsicht mit Therapieweisung befanden. Darüber hinaus werden Informationen über die Anwendung von Rehabilitationsmodellen, therapeutische Ansätze und die Implementierung von standardisierten diagnostischen Verfahren sowie Kriminalprognoseinstrumenten dargestellt. Schließlich werden die Ergebnisse von Evaluationsstudien zu den teilnehmenden Einrichtungen vorgestellt

Readout for intersatellite laser interferometry: Measuring low frequency phase fluctuations of HF signals with microradian precision

Precision phase readout of optical beat note signals is one of the core techniques required for intersatellite laser interferometry. Future space based gravitational wave detectors like eLISA require such a readout over a wide range of MHz frequencies, due to orbit induced Doppler shifts, with a precision in the order of $\mu \textrm{rad}/\sqrt{\textrm{Hz}}$ at frequencies between $0.1\,\textrm{mHz}$ and $1\,\textrm{Hz}$. In this paper, we present phase readout systems, so-called phasemeters, that are able to achieve such precisions and we discuss various means that have been employed to reduce noise in the analogue circuit domain and during digitisation. We also discuss the influence of some non-linear noise sources in the analogue domain of such phasemeters. And finally, we present the performance that was achieved during testing of the elegant breadboard model of the LISA phasemeter, that was developed in the scope of an ESA technology development activity.Comment: submitted to Review of Scientific Instruments on April 30th 201