Contracting in the Absence of Specific Investments and Moral Hazard: Understanding Carrier-Driver Relations in U.S. Trucking

This paper considers functions of contracting other than the protection of relationship-specific investments and the provision of marginal incentives, and applies the theory to explain variation in the form of compensation of over-the-road truck drivers in the U.S. Specifically, we argue that contracts in this industry serve to economize on the costs of price determination for heterogeneous transactions. We show that the actual terms of those contracts vary systematically with the nature of hauls in a way that is consistent with the theory. By contrast, we find that vehicle ownership, which defines a driver's status as an owner operator or company driver, depends on driver, but not trailer or haul, characteristics.

Retail Contracting: Theory and Practice

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73114/1/1467-6451.00032.pd

Ground state of the Kagome-like S=1/2 antiferromagnet, Volborthite Cu3V2O7(OH)2.2H2O

Volborthite compound is one of the very few realizations of S=1/2 quantum spins on a highly frustrated kagome-like lattice. Low-T SQUID measurements reveal a broad magnetic transition below 2K which is further confirmed by a peak in the 51V nuclear spin relaxation rate (1/T1) at 1.4K$\pm$0.2K. Through 51V NMR, the ground state (GS) appears to be a mixture of different spin configurations, among which 20% correspond to a well defined short range order, possibly of the $\sqrt{3} \times \sqrt{3}$ type. While the freezing involve all the Cu$^{2+}$ spins, only 40% of the copper moment is actually frozen which suggests that quantum fluctuations strongly renormalize the GS.Comment: 4 pages, 4 figures, to appear in PR

Vertical integration and firm boundaries : the evidence

Since Ronald H. Coase's (1937) seminal paper, a rich set of theories has been developed that deal with firm boundaries in vertical or input–output structures. In the last twenty-five years, empirical evidence that can shed light on those theories also has been accumulating. We review the findings of empirical studies that have addressed two main interrelated questions: First, what types of transactions are best brought within the firm and, second, what are the consequences of vertical integration decisions for economic outcomes such as prices, quantities, investment, and profits. Throughout, we highlight areas of potential cross-fertilization and promising areas for future work

Incentive Contracting and the Franchise Decision

We examine theoretical predictions and econometric evidence concerning franchise contracting and sales-force compensation and suggest a number of factors that ought to influence the contracts that are written between principles and agents. For each factor, we construct the simplest theoretical model that is capable of capturing what we feel to be its essence. The comparative statics from the theoretical exercise are then used to organize our discussion of the empirical evidence, where the evidence is taken from published studies that have attempted to assess each factor's effect on the power of agent incentives. We also discuss theoretical issues and empirical results pertaining to a few topics that have been addressed in the literature but that do not fit easily into our simple modeling framework. A surprising finding of our survey of retail contracting under exclusive marks is the robust nature of the evidence: although researchers assess different industries over different time periods using a number of proxies for a given factor, their empirical findings are usually consistent with one another.

Use of thyroid hormones in hypothyroid and euthyroid patients: A survey of members of the Endocrine Society of Australia

\ua9 2024 The Authors. Clinical Endocrinology published by John Wiley & Sons Ltd.Objective: Hypothyroidism is a common endocrine condition usually managed with levothyroxine (LT4). However, controversy remains around the use of liothyronine (LT3). We aimed to investigate the practices of Australian endocrinologists when managing patients with hypothyroidism, their use of LT3 + LT4 combination therapy and use of thyroid hormones in euthyroid patients. Design and Participants: Members of the Endocrine Society of Australia (ESA) were invited to participate in an online questionnaire. Measurements: We analysed questionnaires that had complete demographic data. Results: Eighty-seven questionnaires fulfilled the criteria. LT4 was used as first line treatment for hypothyroidism by all respondents. Only 45% reported that their patients were dispensed the brand of LT4 that they recommend. LT3 (alone or in combination) was prescribed by 44% in their clinical practice. Although 49% of respondents would consider LT3 + LT4 in patients with normal TSH who had ongoing symptoms of hypothyroidism, the inability of LT4 to restore normal physiology was ranked the least likely explanation for persistent symptoms and only 32% would consider it for themselves if they were diagnosed with hypothyroidism. The majority (55%), in accordance with evidence, would not prescribe thyroid hormone to euthyroid individuals but 39% would consider use in euthyroid female infertility with high levels of thyroid antibodies and 11% in euthyroid patients with a simple goitre growing over time. LT4 use in pregnancy was variable among members. Conclusions: Australian endocrinologists mostly follow international guidelines when prescribing thyroid hormone therapy and many prescribe combination LT3 and LT4 therapy, particularly for patients who remain symptomatic on LT4 monotherapy. Prescribing practices are largely similar to other countries who have completed similar questionnaires

Scaling and the Metal-Insulator Transition in Si/SiGe Quantum Wells

The existence of a metal-insulator transition at zero magnetic field in two- dimensional electron systems has recently been confirmed in high mobility Si-MOSFETs. In this work, the temperature dependence of the resistivity of gated Si/SiGe/Si quantum well structures has revealed a similar metal- insulator transition as a function of carrier density at zero magnetic field. We also report evidence for a Coulomb gap in the temperature dependence of the resistivity of the dilute 2D hole gas confined in a SiGe quantum well. In addition, the resistivity in the insulating phase scales with a single parameter, and is sample independent. These results are consistent with the occurrence of a metal-insulator transition at zero magnetic field in SiGe square quantum wells driven by strong hole-hole interactions.Comment: 3 pages, 3 figures, LaTe

Stress-driven instability in growing multilayer films

We investigate the stress-driven morphological instability of epitaxially growing multilayer films, which are coherent and dislocation-free. We construct a direct elastic analysis, from which we determine the elastic state of the system recursively in terms of that of the old states of the buried layers. In turn, we use the result for the elastic state to derive the morphological evolution equation of surface profile to first order of perturbations, with the solution explicitly expressed by the growth conditions and material parameters of all the deposited layers. We apply these results to two kinds of multilayer structures. One is the alternating tensile/compressive multilayer structure, for which we determine the effective stability properties, including the effect of varying surface mobility in different layers, its interplay with the global misfit of the multilayer film, and the influence of asymmetric structure of compressive and tensile layers on the system stability. The nature of the asymmetry properties found in stability diagrams is in agreement with experimental observations. The other multilayer structure that we study is one composed of stacked strained/spacer layers. We also calculate the kinetic critical thickness for the onset of morphological instability and obtain its reduction and saturation as number of deposited layers increases, which is consistent with recent experimental results. Compared to the single-layer film growth, the behavior of kinetic critical thickness shows deviations for upper strained layers.Comment: 27 pages, 11 figures; Phys. Rev. B, in pres

Identification of Burkholderia mallei and Burkholderia pseudomallei adhesins for human respiratory epithelial cells

<p>Abstract</p> <p>Background</p> <p><it>Burkholderia pseudomallei </it>and <it>Burkholderia mallei </it>cause the diseases melioidosis and glanders, respectively. A well-studied aspect of pathogenesis by these closely-related bacteria is their ability to invade and multiply within eukaryotic cells. In contrast, the means by which <it>B. pseudomallei </it>and <it>B. mallei </it>adhere to cells are poorly defined. The purpose of this study was to identify adherence factors expressed by these organisms.</p> <p>Results</p> <p>Comparative sequence analyses identified a gene product in the published genome of <it>B. mallei </it>strain ATCC23344 (locus # BMAA0649) that resembles the well-characterized <it>Yersinia enterocolitica </it>autotransporter adhesin YadA. The gene encoding this <it>B. mallei </it>protein, designated <it>boaA</it>, was expressed in <it>Escherichia coli </it>and shown to significantly increase adherence to human epithelial cell lines, specifically HEp2 (laryngeal cells) and A549 (type II pneumocytes), as well as to cultures of normal human bronchial epithelium (NHBE). Consistent with these findings, disruption of the <it>boaA </it>gene in <it>B. mallei </it>ATCC23344 reduced adherence to all three cell types by ~50%. The genomes of the <it>B. pseudomallei </it>strains K96243 and DD503 were also found to contain <it>boaA </it>and inactivation of the gene in DD503 considerably decreased binding to monolayers of HEp2 and A549 cells and to NHBE cultures.</p> <p>A second YadA-like gene product highly similar to BoaA (65% identity) was identified in the published genomic sequence of <it>B. pseudomallei </it>strain K96243 (locus # BPSL1705). The gene specifying this protein, termed <it>boaB</it>, appears to be <it>B. pseudomallei</it>-specific. Quantitative attachment assays demonstrated that recombinant <it>E. coli </it>expressing BoaB displayed greater binding to A549 pneumocytes, HEp2 cells and NHBE cultures. Moreover, a <it>boaB </it>mutant of <it>B. pseudomallei </it>DD503 showed decreased adherence to these respiratory cells. Additionally, a <it>B. pseudomallei </it>strain lacking expression of both <it>boaA </it>and <it>boaB </it>was impaired in its ability to thrive inside J774A.1 murine macrophages, suggesting a possible role for these proteins in survival within professional phagocytic cells.</p> <p>Conclusions</p> <p>The <it>boaA </it>and <it>boaB </it>genes specify adhesins that mediate adherence to epithelial cells of the human respiratory tract. The <it>boaA </it>gene product is shared by <it>B. pseudomallei </it>and <it>B. mallei </it>whereas BoaB appears to be a <it>B. pseudomallei</it>-specific adherence factor.</p

Regional Brain Stem Atrophy in Idiopathic Parkinson's Disease Detected by Anatomical MRI

Idiopathic Parkinson's disease (PD) is a neurodegenerative disorder characterized by the dysfunction of dopaminergic dependent cortico-basal ganglia loops and diagnosed on the basis of motor symptoms (tremors and/or rigidity and bradykinesia). Post-mortem studies tend to show that the destruction of dopaminergic neurons in the substantia nigra constitutes an intermediate step in a broader neurodegenerative process rather than a unique feature of Parkinson's disease, as a consistent pattern of progression would exist, originating from the medulla oblongata/pontine tegmentum. To date, neuroimaging techniques have been unable to characterize the pre-symptomatic stages of PD. However, if such a regular neurodegenerative pattern were to exist, consistent damages would be found in the brain stem, even at early stages of the disease. We recruited 23 PD patients at Hoenn and Yahr stages I to II of the disease and 18 healthy controls (HC) matched for age. T1-weighted anatomical scans were acquired (MPRAGE, 1 mm3 resolution) and analyzed using an optimized VBM protocol to detect white and grey matter volume reduction without spatial a priori. When the HC group was compared to the PD group, a single cluster exhibited statistical difference (p<0.05 corrected for false detection rate, 4287 mm3) in the brain stem, between the pons and the medulla oblongata. The present study provides in-vivo evidence that brain stem damage may be the first identifiable stage of PD neuropathology, and that the identification of this consistent damage along with other factors could help with earlier diagnosis in the future. This damage could also explain some non-motor symptoms in PD that often precede diagnosis, such as autonomic dysfunction and sleep disorders