(Psycho-)Analysis of Benchmark Experiments

It is common knowledge that certain characteristics of data sets -- such as linear separability or sample size -- determine the performance of learning algorithms. In this paper we propose a formal framework for investigations on this relationship. The framework combines three, in their respective scientific discipline well-established, methods. Benchmark experiments are the method of choice in machine and statistical learning to compare algorithms with respect to a certain performance measure on particular data sets. To realize the interaction between data sets and algorithms, the data sets are characterized using statistical and information-theoretic measures; a common approach in the field of meta learning to decide which algorithms are suited to particular data sets. Finally, the performance ranking of algorithms on groups of data sets with similar characteristics is determined by means of recursively partitioning Bradley-Terry models, that are commonly used in psychology to study the preferences of human subjects. The result is a tree with splits in data set characteristics which significantly change the performances of the algorithms. The main advantage is the automatic detection of these important characteristics. The framework is introduced using a simple artificial example. Its real-word usage is demonstrated by means of an application example consisting of thirteen well-known data sets and six common learning algorithms. All resources to replicate the examples are available online

Moral Hazard and the Composition of Transfers: Theory with an Application to Foreign Aid

The paper presents a theoretical and empirical analysis of a donor’s choice of the composition of unrestricted and in-kind/restricted transfers to a recipient and how this composition is adjusted in response to changes in the moral hazard behavior of the recipient. In-kind or restricted transfers may be used, among others, to control a recipient’s moral hazard behavior but may be associated with deadweight losses. Within the context of foreign aid, we use a canonical political agency model to construct a simple signaling game between a possibly corrupt politician in a recipient country and a donor to illustrate the donor’s optimal choice of tied (restricted) and untied foreign aid. We clarify the condition under which a reduction in the recipient’s moral hazard behavior (i.e., improvement in the level of governance) leads to a fall in the proportion of tied aid. We test the predictions of our theoretical analysis using data on the composition of foreign aid by multilateral and bilateral donors.tied foreign aid, governance, moral hazard, political agency, restricted transfer

Moral Hazard and the Composition of Transfers: Theory with an Application to Foreign Aid

The paper presents a theoretical and empirical analysis of a donors choice of the composition of unrestricted and in-kind/restricted transfers to a recipient and how this composition is adjusted in response to changes in the moral hazard behavior of the recipient. In-kind or restricted transfers may be used, among others, to control a recipients moral hazard behavior but may be associated with deadweight losses. Within the context of foreign aid, we use a canonical political agency model to construct a simple signaling game between a possibly corrupt politician in a recipient country and a donor to illustrate the donors optimal choice of tied (restricted) and untied foreign aid. We clarify the condition under which a reduction in the recipients moral hazard behavior (i.e., improvement in the level of governance) leads to a fall in the proportion of tied aid. We test the predictions of our theoretical analysis using data on the composition of foreign aid by multilateral and bilateral donors. --Moral Hazard,Foreign Aid,Panel Data

Moral Hazard and the Composition of Transfers: Theory with an Application to Foreign Aid

The paper presents a theoretical and empirical analysis of a donor’s choice of the composition of unrestricted and in-kind/restricted transfers to a recipient and how this composition is adjusted in response to changes in the moral hazard behavior of the recipient. In-kind or restricted transfers may be used, among others, to control a recipient’s moral hazard behavior but may be associated with deadweight losses. Within the context of foreign aid, we use a canonical political agency model to construct a simple signaling game between a possibly corrupt politician in a recipient country and a donor to illustrate the donor’s optimal choice of tied (restricted) and untied foreign aid. We clarify the condition under which a reduction in the recipient’s moral hazard behavior (i.e., improvement in the level of governance) leads to a fall in the proportion of tied aid. We test the predictions of our theoretical analysis using data on the composition of foreign aid by multilateral and bilateral donors.tied foreign aid; governance; moral hazard; political agency; restricted transfer

Explicit Global Coordinates for Schwarzschild and Reissner-Nordstroem

We construct coordinate systems that cover all of the Reissner-Nordstroem solution with m>|q| and m=|q|, respectively. This is possible by means of elementary analytical functions. The limit of vanishing charge q provides an alternative to Kruskal which, to our mind, is more explicit and simpler. The main tool for finding these global charts is the description of highly symmetrical metrics by two-dimensional actions. Careful gauge fixing yields global representatives of the two-dimensional theory that can be rewritten easily as the corresponding four-dimensional line elements.Comment: 12 pages, 3 Postscript figures, sign error in Eq. (37) and below corrected, references and Note added; to appear in Class. Quantum Gra

Design of a horizontal neutron reflectometer for the European Spallation Source

A design study of a horizontal neutron reflectometer adapted to the general baseline of the long pulse European Spallation Source (ESS) is presented. The instrument layout comprises solutions for the neutron guide, high-resolution pulse shaping and beam bending onto a sample surface being so far unique in the field of reflectometry. The length of this instrument is roughly 55 m, enabling $\delta \lambda / \lambda$ resolutions from 0.5% to 10%. The incident beam is focussed in horizontal plane to boost measurements of sample sizes of 1*1 cm{^2} and smaller with potential beam deflection in both downward and upward direction. The range of neutron wavelengths untilized by the instrument is 2 to 7.1 (12.2, ...) {\AA}, if every (second, ...) neutron source ulse is used. Angles of incidence can be set between 0{\deg} and 9{\deg} with a total accessible q-range from 4*10^{-3} {\AA}^{-1} up to 1 {\AA}^{-1}. The instrument operates both in {\theta}/{\theta} (free liquid surfaces) and {\theta}/2{\theta} (solid/liquid, air/solid interfaces) geometry. The experimental setup will in particular enable direct studies on ultrathin films (d ~ 10 {\AA}) and buried monolayers to multilayered structures of up to 3000 {\AA} total thickness. The horizontal reflectometer will further foster investigations of hierarchical systems from nanometer to micrometer length scale, as well as their kinetics and dynamical properties, in particular under load (shear, pressure, external fields). Polarization and polarization analysis as well as the GISANS option are designed as potential modules to be implemented separately in the generic instrument layout. The instrument is highly flexible and offers a variety of different measurement modes. With respect to its mechanical components the instrument is exclusively based on current technology. Risks of failure for the chosen setup are minimum.Comment: Matched to the version submitted to Nuclear Instruments and Methods

Symplectic Cuts and Projection Quantization

The recently proposed projection quantization, which is a method to quantize particular subspaces of systems with known quantum theory, is shown to yield a genuine quantization in several cases. This may be inferred from exact results established within symplectic cutting.Comment: 12 pages, v2: additional examples and a new reference to related wor

Identification of epidermal Pdx1 expression discloses different roles of Notch1 and Notch2 in murine KrasG12D-induced skin carcinogenesis in vivo

Background The Ras and Notch signaling pathways are frequently activated during development to control many diverse cellular processes and are often dysregulated during tumorigenesis. To study the role of Notch and oncogenic Kras signaling in a progenitor cell population, Pdx1-Cre mice were utilized to generate conditional oncogenic KrasG12D mice with ablation of Notch1 and/or Notch2. Methodology/Principal Findings Surprisingly, mice with activated KrasG12D and Notch1 but not Notch2 ablation developed skin papillomas progressing to squamous cell carcinoma providing evidence for Pdx1 expression in the skin. Immunostaining and lineage tracing experiments indicate that PDX1 is present predominantly in the suprabasal layers of the epidermis and rarely in the basal layer. Further analysis of keratinocytes in vitro revealed differentiation-dependent expression of PDX1 in terminally differentiated keratinocytes. PDX1 expression was also increased during wound healing. Further analysis revealed that loss of Notch1 but not Notch2 is critical for skin tumor development. Reasons for this include distinct Notch expression with Notch1 in all layers and Notch2 in the suprabasal layer as well as distinctive p21 and β-catenin signaling inhibition capabilities. Conclusions/Significance Our results provide strong evidence for epidermal expression of Pdx1 as of yet not identified function. In addition, this finding may be relevant for research using Pdx1-Cre transgenic strains. Additionally, our study confirms distinctive expression and functions of Notch1 and Notch2 in the skin supporting the importance of careful dissection of the contribution of individual Notch receptors