The Adoption of Water Conservation and Intensification Technologies and Farm Income: A Propensity Score Analysis for Rice Farmers in Northern Ghana

This study uses cross-sectional data of 342 small-scale lowland rice farmers in Northern Region of Ghana to analyze the impact of the adoption decision of bund construction and seed dibbling on net returns, input demand and output supply. Matching was conducted based on Mahalanobis distance combined with propensity score. Balancing tests by checking the mean standardized absolute bias in the matched sample were conducted as well as sensitivity analysis to check for hidden bias due to unobservable selection. The empirical results of impact assessment using propensity score matching controlling for self-selection bias suggest that input demand is significantly higher for adopters of bunds, but not statistically different for adopters and non-adopters of dibbling seed. However, output supply and net returns were not found to be statistically different for adopters and non-adopters of bunds. Adopters of dibbling were found to have higher output supply while no statistically significant difference was found for net returns of adopters and non-adopters of dibbling. The results were found to be relative insensitive to hidden bias.Propensity score matching, evaluation, sensitivity analysis, Rosenbaum bounds, water conservation methods, bunds, rice production, Crop Production/Industries, Farm Management,

Internationalization field lab of ps: an in-depth analysis of Norway

Internationalization is a strategic challenge for small companies. This paper aims to provide an analytic procedure for the Portuguese luxury real estate agency of PS by defining the target market for expansion, an appropriate market entry mode, and an applicable marketing plan along a financial forecast. Literature was reviewed to identify the criteria to be considered when selecting the market entry mode. An in-depth analysis of Norway revealed that while it offers a favorable environment for operating as a real estate broker with a focus on international clients, strict requirements and limited commissions reduce the country’s attractiveness

A Surgical Perspective on Targeted Therapy of Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC), the second leading cause of cancer deaths worldwide, is difficult to treat and highly lethal. Since HCC is predominantly diagnosed in patients with cirrhosis, treatment planning must consider both the severity of liver disease and tumor burden. To minimize the impact to the patient while treating the tumor, techniques have been developed to target HCC. Anatomical targeting by surgical resection or locoregional therapies is generally reserved for patients with preserved liver function and minimal to moderate tumor burden. Patients with decompensated cirrhosis and small tumors are optimal candidates for liver transplantation, which offers the best chance of long-term survival. Yet, only 20%-30% of patients have disease amenable to anatomical targeting. For the majority of patients with advanced HCC, chemotherapy is used to target the tumor biology. Despite these treatment options, the five-year survival of patients in the United States with HCC is only 16%. In this review we provide a comprehensive overview of current approaches to target HCC. We also discuss emerging diagnostic and prognostic biomarkers, novel therapeutic targets identified by recent genomic profiling studies, and potential applications of immunotherapy in the treatment of HCC

The evaluation of corrosion inhibitors for application to copper and copper alloy archaeological artefacts

This thesis concerns corrosion inhibiting compounds which slow the deterioration of archaeological copper artefacts. Benzotriazole (BTA) and 2-Amino- 5-mercapto-1,3,4-thiadiazole (AMT) have been applied as corrosion inhibitors in archaeological conservation. A search was conducted for similar compounds that could be applied in the conservation of copper and copper alloys. According to a list of requirements specific to archaeological conservation, six new inhibitors were tested. 2-Aminopyrimidine (AP), 5,6-Dimethylbenzimidazole (DB), 2-Mercaptobenzimidazole (MBI), 2-Mercaptobenzoxazole (MBO), 2-Mercaptobenzothiazole (MBT), 2-Mercaptopyrimidine (MP), were tested for potential archaeological conservation applications. The literature 1ists only one corrosion test for copper chloride corrosion in archaeological conservation, with intact surface corrosion products. Industrial corrosion tests were checked in American Society for Testing Materials (ASTM), British Standards Institution (BSI), Deutsche Industry Norm (DIN), International Standards Organisation (ISO). Chlorides are known to be a major factor in ongoing deterioration of copper artefacts in the museum environment. The mechanisms and types of chloride corrosion are discussed, including past and recent literature on the subject. No corrosion test was found entirely suitable for the evaluation of corrosion inhibitors against corroded metallic surfaces in conservation, so an appropriate corrosion test had to be developed. Copper coupons were immersed into cupric chloride solutions to produce cuprous chloride corrosion, the structure of which is similar to corrosion found directly against remaining metal of artefacts. These coupons were subsequently treated with corrosion inhibitor solutions, and exposed to elevated relative humidity to assess corrosion inhibition, by monitoring the weight changes during the experiments. The inhibitor solutions were analysed regarding the depletion of copper in copper corrosion products, using Atomic Absorption Photospectroscopy (AAS). The colour changes of copper corrosion products treated with inhibitor solutions were determined using a chroma meter. According to these findings AMT, and MBT were selected for more extensive performance tests against BTA on archaeological metal artefacts

Terahertz Laser Induced Ratchet Effects and Magnetic Quantum Ratchet Effects in Semiconductor Nanostructures

In the framework of this thesis, different magnetic quantum ratchet effects were firstly discovered which were generated by the excitation of dual grating gate samples with terahertz radiation in the presence of a magnetic field. These effects were observed in various CdTe and (Cd,Mn)Te samples with different parameters of the top gate structure. The observed magnetic quantum ratchet currents exhibit sign-changing magneto-oscillations with an amplitude by orders larger than the photocurrent at zero magnetic field. These oscillations are 1/B-periodic and they are in phase with the derivative of the Shubnikov-de Haas oscillations. The current amplitude and direction were controllably changed by the variation of the lateral potential asymmetry parameter, induced by the voltages applied to the thin or wide gate stripes. Moreover, the amplitude and the sign of the current oscillations were altered by the inplane orientation of the electric field in respect to the double grating gate structure for the linear magnetic ratchet effect or by the radiation helicity for the circular magnetic ratchet effect. The photocurrent formation is well described in terms of the theory developed simultaneously to the experiments. Here, the lateral dual grating gate has two tasks: First, it induces a periodical lateral potential acting on the electrons in the quantum well and second, this grating modulates the incident radiation in the near-field and hence in the plane of the two-dimensional electron gas. In fact, the generated photocurrent consists of three different contributions, namely the Seebeck (polarization independent), the linear and the circular magnetic quantum ratchet current. They are caused by different physical principles which will be briefly explained in the following. The polarization independent photocurrent is well described in terms of the semiclassical theory of the Seebeck magnetic ratchet effects. The observed effect is driven by the periodic modulation of the electron temperature in the two-dimensional electron gas which is caused by the local heating induced by the electrical near-field diffraction at the dual grating gate structure. The theory of the Seebeck ratchet effect in the presence of a quantizing magnetic field shows that the ratchet current follows the longitudinal magneto-resistance oscillations and the numerical calculations of the Seebeck ratchet current fit well to the experimental data. The theoretical explanation of the polarization dependent ratchet currents considers the different polarization states of the radiation, the static conductivity tensor and the time-dependent spatially periodic electron density oscillations which are linear in both the electric field and the lateral potential. All considered mechanisms for explaining the magnetic ratchet effect were shown to be of orbital nature. The idea of building a detector based on the ratchet effect to detect different polarization states of the radiation was realized by applying terahertz radiation to dual grating gate InAlAs/InGaAs/InAlAs/InP high electron mobility transistors resulting in a polarization sensitive photocurrent response at room temperature. This work demonstrates that high electron mobility transistors with an asymmetric lateral superlattice of gate fingers with unequal widths and spacing can be applied for generation of a photocurrent caused by linearly and circularly polarized radiation. Although the reported responsivity of field effect transistor detectors is higher than the ones obtained in this work, the measured currents change their amplitude and sign by variation of the polarization states as well as by changing the lateral asymmetry parameter which was not observed up to now. Furthermore, the obtained photocurrents can be proportional to one selected Stokes parameter simply by variation of the voltages applied to the individual gates, offering new possibilities for detecting

Spektroskopische Untersuchungen zum Wasserstoffselbstaustausch bei Phenoxy-Radikalen und der sensitivierten Triplett-Triplett-Annihilation

Diese Arbeit ist in zwei Themengebiete geteilt. Der erste Teil befasst sich mit dem Wasserstoff(selbst)austausch zwischen Phenol und einem Phenoxy-Radikal. Die Untersuchung dieses Selbstaustausches findet über die Betrachtung von Pseudo- Selbstaustausch-Reaktionen statt, da mit optischer Spektroskopie keine Möglichkeit besteht den Selbstaustausch direkt zu verfolgen. Dazu kommen deuterierte und methylierte Phenol-Derivate zum Einsatz. Der zweite Teil betrachtet eine Reihe von Photonen-Hochkonversions-Systemen, deren Mechanismus über eine sensitivierte Triplett-Triplett-Annihilation abläuft. Hier wird unter anderem die eignung eines solchen Systems als Photokatalysator untersucht. Die zentrale Untersuchungsmethode ist dabei in beiden Fällen die Transiente Absorption im μs-Zeitbereich, unter Anderem unterstützt durch UV-Vis-Spektroskopie, GC- und LC-Chromatographie und Cyclovoltametrie

Adoption and economic impact of water conservation and intensification methods on input demand, output supply, and net returns in lowland rice production of northern Ghana

Rice is an important cereal to Ghana’s economy and agriculture. While there is huge potential for lowland rice cultivation in northern Ghana, erratic rainfall and low and degrading soil fertility remain the key constraints of production. The present study analyzes the adoption decision and the impact of bund technology and dibbling method on fertilizer demand, output supply, and net returns. The present analysis explicitly takes account of selection bias by employing endogenous switching regression and propensity score matching. The cross-sectional data set refers to the cropping season 2005 and consists of 342 smallholder rice farmers. Results of the seemingly unrelated bivariate probit model suggest that the adoption decisions of dibbling and bund technology should be estimated jointly. Estimates indicate that bunds are more likely constructed on marginal land as a preventive technology, while dibbling method seems to be used complementary to good soil productivity. Adoption decisions are found to be related to economic constraints, particularly of labour and capital, while off-farm income appears to decrease the adoption of labour-intensive technologies. Furthermore, adoption seems to be strongly related to the use of interrelated technologies, the perception of technologies, participation in technology-related projects and farmer groups, plot-level characteristics, and geographic location. To examine the impact of technology adoption, this study applies Mahalanobis metric matching with calipers and the propensity score as additional variable. This approach is particularly useful in the present analysis with multiple treatments. To check for the robustness of results, kernel based matching and nearest neighbour matching are applied. Balancing tests were conducted by checking the reduction of the mean standardized absolute bias. To control for hidden bias due to selection on unobservables, sensitivity analysis was done by employing the Rosenbaum (2002) bounding approach. Results indicate the significance of matching in reducing bias in the distribution of relevant variables between the treatment and control group and that the estimates are quite insensitive to hidden bias. Results of the Mahalanobis metric matching indicate that the adoption of bund technology has a positive and significant effect on fertilizer demand, as well as a positive, but insignificant impact on output supply and net returns. Adopters of dibbling appear to have higher rice yields, while no significant difference in net returns and fertilizer demand was found. However, data reveal a positive and significant effect on output supply and net returns when dibbling method is combined with intensified weeding. Furthermore, when dibbling is not only used as seed sowing but also as fertilizer application method, nitrogen demand is significantly higher. The estimates of the endogenous switching regression model suggest that self-selection occurs. Labour and capital constraints, the use of interrelated technologies, social networks such as farmer groups, education, learning effects through the dissemination and the use of interrelated technologies, and the timely availability of land preparation equipment appear to be important factors in determining farm outcomes. However, the effects vary in the level and significance according to the type of technology and outcome. This supports the need to examine the impact of determinants separately for adopters and non-adopters

Helicity sensitive terahertz radiation detection by dual-grating-gate high electron mobility transistors

We report on the observation of a radiation helicity sensitive photocurrent excited by terahertz (THz) radiation in dual-grating-gate (DGG) InAlAs/InGaAs/InAlAs/InP high electron mobility transistors (HEMT). For a circular polarization the current measured between source and drain contacts changes its sign with the inversion of the radiation helicity. For elliptically polarized radiation the total current is described by superposition of the Stokes parameters with different weights. Moreover, by variation of gate voltages applied to individual gratings the photocurrent can be defined either by the Stokes parameter defining the radiation helicity or those for linear polarization. We show that artificial non-centrosymmetric microperiodic structures with a two-dimensional electron system excited by THz radiation exhibit a dc photocurrent caused by the combined action of a spatially periodic in-plane potential and spatially modulated light. The results provide a proof of principle for the application of DGG HEMT for all-electric detection of the radiation's polarization state.Comment: 7 pages, 4 figure