The Evolution of Buyout Pricing and Financial Structure

This paper presents evidence on systematic changes in the pricing and financial structure of 124 large management buyouts completed between 1980 and 1989. We find that over tine (1) prices increased relative to current cash flows with no accompanying decrease in risk or increase in projected future cash flows; (2) required bank principal repayments accelerated, leading to sharply lower ratios of cash flow to total debt obligations; (3) private subordinated debt was replaced by public debt while the use of strip-financing techniques declined; and (4) management teams invested a smaller fraction of their net worth in post-buyout equity. These patterns of buyout prices and structures suggest that based on ex ante data, one could have expected lower returns and more frequent financial distress in later buyouts. Preliminary post-buyout evidence is consistent with this interpretation.

ENSO dynamics: low-dimensional-chaotic or stochastic?

We apply a test for low-dimensional, deterministic dynamics to the Nino 3 time series for the El Nino Southern Oscillation (ENSO). The test is negative, indicating that the dynamics is high-dimensional/stochastic. However, application of stochastic forcing to a time-delay equation for equatorial-wave dynamics can reproduce this stochastic dynamics and other important aspects of ENSO. Without such stochastic forcing this model yields low-dimensional, deterministic dynamics, hence these results emphasize the importance of the stochastic nature of the atmosphere-ocean interaction in low-dimensional models of ENSO

Structure of Quantum Chaotic Wavefunctions: Ergodicity, Localization, and Transport

We discuss recent developments in the study of quantum wavefunctions and transport in classically ergodic systems. Surprisingly, short-time classical dynamics leaves permanent imprints on long-time and stationary quantum behavior, which are absent from the long-time classical motion. These imprints can lead to quantum behavior on single-wavelength or single-channel scales which are very different from random matrix theory expectations. Robust and quantitative predictions are obtained using semiclassical methods. Applications to wavefunction intensity statistics and to resonances in open systems are discussed.Comment: 8 pages, including 2 figures; talk given at `Dynamics of Complex Systems' workshop in Dresden, 1999 and submitted for conference proceedings to appear in Physica

Sub-Riemannian Calculus on Hypersurfaces in Carnot Groups

We develope basic geometric quantities and properties of hypersurfaces in Carnot groups

Evolving Therapeutic Strategies for the Classic Philadelphia-Negative Myeloproliferative Neoplasms

AbstractDespite the emergence of JAK inhibitors, there is a need for disease-modifying treatments for Philadelphia-negative myeloproliferative neoplasms (MPNs). JAK inhibitors ameliorate symptoms and address splenomegaly, but because of the heterogeneous contributors to the disease process, JAK inhibitor monotherapy incompletely addresses the burden of disease. The ever-growing understanding of MPN pathogenesis has provided the rationale for testing novel and targeted therapeutic agents, as monotherapies or in combination, in preclinical and clinical settings. A number of intriguing options have emerged, and it is hoped that further progress will lead to significant changes in the natural history of MPNs

La inquietante presencia de la muerte. Su representación en el arte uruguayo en tiempos de la Segunda Guerra Mundial.

El impacto de la Segunda Guerra Mundial en Uruguay ha sido tradicionalmente estudiado por la historiografía desde su costado socioeconómico, existiendo un gran vacío al respecto de su huella en el espacio cultural y artístico. El presente artículo se propone analizar, precisamente, aquellos cambios del corpus artístico uruguayo en relación con las representaciones de la muerte –en términos iconográficos, formales y expresivos– a partir de la Segunda Guerra Mundial. Por un lado, se estudian vertientes iconográficas relacionadas a la presencia explícita de la muerte, mientras que por otro se sugiere una serie de obras en las que se desarrollan tópicos y atmósferas que se vinculan de manera indirecta, aunque sin aludir llanamente a ella. Es en este caso donde destaca la presencia melancólica de una manera omnipresente

Correlation with basic differentiation processes of neurons

The development of the spinal cord involves the proliferation of neurons, their migration to well-defined areas, fiber outgrowth and synapse formation. The present study was designed to correlate the spatiotemporal pattern of expression of synaptophysin, an integral membrane protein of small synaptic vesicles, with these basic processes occurring during the embryonic development of the rat spinal cord. Thoracic segments of spinal cords from embryonic days 12, 14, 16, 18, 20 and of adult spinal cords were studied. S1 nuclease protection assays and immunoblots revealed minute amounts of specific mRNA and synaptophysin at embryonic day 12. There was a steep increase of mRNA between embryonic days 14 and 16, after which levels reached a plateau. A rise in the amount of synaptophysin in the spinal cord occurred between embryonic days 12 and 14, and the levels changed only slightly until the end of embryonic development. Even higher levels of synaptophysin, found in the adult spinal cord, may indicate that its biosynthesis continued after birth. In situ hybridization histochemistry revealed the localization of specific synaptophysin mRNA in the neuroepithelium. However, immunocytochemistry failed to detect synaptophysin in the neuroepithelial cells. Following migration of the neuroblasts, synaptophysin was found in neurons concomitantly with the onset of fiber outgrowth. Thus, already at embryonic day 12, outgrowing fibers of the dorsal root sensory neurons and of motoneurons were synaptophysin positive. From embryonic day 14 throughout the prenatal period, strong synaptophysin immunoreactivity was seen in the ventrolateral and dorsal parts of the marginal layer. Most likely this staining pattern indicates transient functional synaptic contacts because, in the adult spinal cord, the corresponding region, the white matter, exhibited only faint synaptophysin immunoreactivity. In the intermediate layer of the embryonic spinal cord, which corresponds to the gray matter of the adult spinal cord, synaptophysin-positive fibers were observed prior to the formation of functional synapses. The latter are most likely permanent, since synaptophysin in the adult spinal cord is mainly confined to the gray matter. Our data (i) show transcription and translation of synaptophysin within the neurons of the spinal cord and correlate these processes with proliferation, migration, fiber outgrowth and the formation of transient or permanent synapses, and (ii) prove that synaptophysin is a marker for fiber outgrowth in addition to synapse formation

Explicit infrastructure for real quadratic function fields and real hyperelliptic curves

In 1989, Koblitz first proposed the Jacobian of a an imaginary hyperelliptic curve for use in public-key cryptographic protocols. This concept is a generalization of elliptic curve cryptography. It can be used with the same assumed key-per-bit strength for small genus. More recently, real hyperelliptic curves of small genus have been introduced as another source for cryptographic protocols. The arithmetic is more involved than its imaginary counterparts and it is based on the so-called infrastructure of the set of reduced principal ideals in the ring of regular functions of the curve. This infrastructure is an interesting phenomenon. The main purpose of this article is to explain the infrastructure in explicit terms and thus extend Shanks\u27 infrastructure ideas in real quadratic number fields to the case of real quadratic congruence function fields and their curves. Hereby, we first present an elementary introduction to the continued fraction expansion of real quadratic irrationalities and then generalize important results for reduced ideals

What drives security issuance decisions: Market timing, pecking order, or both?

We study market timing and pecking order in a sample of debt and equity issues and share repurchases of Canadian firms from 1998 to 2007. We find that only when firms are not financially constrained is there evidence that firms issue (repurchase) equity when their shares are overvalued (undervalued) and evidence that overvalued issuers earn lower postannouncement long-run returns. Similarly, we find that only when firms are not overvalued do they prefer debt to equity financing. These findings highlight an interaction between market timing and pecking order effects

Drawing non-layered tidy trees in linear time

The well-known Reingold–Tilford algorithm produces tidy-layered drawings of trees: drawings where all nodes at the same depth are vertically aligned. However, when nodes have varying heights, layered drawing may use more vertical space than necessary. A non-layered drawing of a tree places children at a fixed distance from the parent, thereby giving a more vertically compact drawing. Moreover, non-layered drawings can also be used to draw trees where the vertical position of each node is given, by adding dummy nodes. In this paper, we present the first linear-time algorithm for producing non-layered drawings. Our algorithm is a modification of the Reingold–Tilford algorithm, but the original complexity proof of the Reingold–Tilford algorithm uses an invariant that does not hold for the non-layered case. We give an alternative proof of the algorithm and its extension to non-layered drawings. To improve drawings of trees of unbounded degree, extensions to the Reingold–Tilford algorithm have been proposed. These extensions also work in the non-layered case, but we show that they then cause a O(n2) run-time. We then propose a modification to these extensions that restores the O(n) run-time