Poison or Placebo? Evidence on the Deterrent and Wealth Effects of Modern Antitakeover Measures

This paper provides large-sample evidence that poison pill rights issues, control share statutes, and business combination statutes do not deter takeovers and are unlikely to have caused the demise of the 1980s market for corporate control, even though 87% of all exchange-listed firms are now covered by one or another of these antitakeover measures. We show that poison pills and control share statutes are reliably associated with higher takeover premiums for selling shareholders, both unconditionally and conditional on a successful takeover, and we provide updated event-study evidence for the three-quarters of all poison pills not yet analyzed.

A link between short-range and long-range properties of random sphere packings

We present a high precision particle-by-particle 3D reconstruction of granular systems composed of monodispersed spheres (sphere packings); the experimental approach is based on magnetic resonance imaging techniques. Our measurements revealed a strong correlation between the volume defined by the distance to the first nearest neighbor and the long-range average density. The main contribution to the amplitude decay of the correlation function can be described as exponential rather than power law up to a range equal to 7 sphere diameters. No evidence of geometrical structural changes as a function of the density was observed and neither regular crystallites nor any other statistically significant structures could be ascribed to a specific local arrangement. We concluded that granular compaction is the result of a process through which the system changes the average size of local structures without changing their local geometrical characteristics. These conclusions are supported by two-body correlation functions and Voronoi polyhedra space decomposition. The results provide a different perspective on the mechanisms underlying compaction with respect to previous works, and allow to discriminate between the different existing theoretical approache

Comment on Partition Function of Anyon Gas

The general structure of the partition function of an anyon gas is discussed, especially in relation to statements made in Phys. Rev. Lett. 68 (1992) 1621 and Phys. Rev. Lett. 69( 1992) 2877.Comment: 5 pages, Tex (This paper, which was published in Phys. Rev. Lett. but was not available on the archives, is cited in the paper ``Calogero-Sutherland Particles as Quasisemions'', hep-th/9609063

Hyperpolarized ¹³C Magnetic Resonance Spectroscopy Reveals the Rate-Limiting Role of the Blood-Brain Barrier in the Cerebral Uptake and Metabolism of l-Lactate in Vivo.

The dynamics of l-lactate transport across the blood-brain barrier (BBB) and its cerebral metabolism are still subject to debate. We studied lactate uptake and intracellular metabolism in the mouse brain using hyperpolarized <sup>13</sup> C magnetic resonance spectroscopy (MRS). Following the intravenous injection of hyperpolarized [1- <sup>13</sup> C]lactate, we observed that the distribution of the <sup>13</sup> C label between lactate and pyruvate, which has been shown to be representative of their pool size ratio, is different in NMRI and C57BL/6 mice, the latter exhibiting a higher level of cerebral lactate dehydrogenase A ( Ldha) expression. On the basis of this observation, and an additional set of experiments showing that the cerebral conversion of [1- <sup>13</sup> C]lactate to [1- <sup>13</sup> C]pyruvate increases after exposing the brain to ultrasound irradiation that reversibly opens the BBB, we concluded that lactate transport is rate-limited by the BBB, with a 30% increase in lactate uptake after its disruption. It was also deduced from these results that hyperpolarized <sup>13</sup> C MRS can be used to detect a variation in cerebral lactate uptake of <40 nmol in a healthy brain during an in vivo experiment lasting only 75 s, opening new opportunities to study the role of lactate in brain metabolism

Spin dependent scattering of a domain-wall of controlled size

Magnetoresistance measurements in the CPP geometry have been performed on single electrodeposited Co nanowires exchange biased on one side by a sputtered amorphous GdCo layer. This geometry allows the stabilization of a single domain wall in the Co wire, the thickness of which can be controlled by an external magnetic field. Comparing magnetization, resistivity, and magnetoresistance studies of single Co nanowires, of GdCo layers, and of the coupled system, gives evidence for an additional contribution to the magnetoresistance when the domain wall is compressed by a magnetic field. This contribution is interpreted as the spin dependent scattering within the domain wall when the wall thickness becomes smaller than the spin diffusion length.Comment: 9 pages, 13 figure

Hyperpolarised 13C MRI: a new horizon for non-invasive diagnosis of aggressive breast cancer

Hyperpolarised 13C MRI (HP-MRI) is a novel imaging technique that allows real-time analysis of metabolic pathways in vivo. 1 The technology to conduct HP-MRI in humans has recently become available and is starting to be clinically applied. As knowledge of molecular biology advances, it is increasingly apparent that cancer cell metabolism is related to disease outcomes, with lactate attracting specific attention. 2 Recent reviews of breast cancer screening programs have raised concerns and increased public awareness of over treatment. The scientific community needs to shift focus from improving cancer detection alone to pursuing novel methods of distinguishing aggressive breast cancers from those which will remain indolent. HP-MRI offers the opportunity to identify aggressive tumour phenotypes and help monitor/predict therapeutic response. Here we report one of the first cases of breast cancer imaged using HP-MRI alongside correlative conventional imaging, including breast MRI

Heterogeneity and Strategic Choices: The Case of Stock Repurchases

Strategic decisions are fundamentally tough choices. Theory suggests that managers are likely to display bounded rationality. Empirics on the other hand assume rationality in choice behavior. Recognizing this inherent disconnect between theory and empirics, we try to account for behavioral biases using a theoretically consistent choice model. The traditional approach to modeling strategic choice has been to use discrete choice models and make inference on the conditional mean effects. We argue that the conditional mean effect does not capture behavioral biases. The focus should be on the conditional variance. Explicitly modeling the conditional variance (in the discrete choice framework) provides us with valuable information on individual level variation in decision-making. We demonstrate the effect of ignoring the role of variance in choice modeling in the context of firm’s decisions to conduct open market repurchases. We show that when taking into account the heterogeneity in choices, manager’s choices of conducting open market repurchases displays considerable heterogeneity and that not accounting for such heterogeneity might lead to wrong conclusions on the mean effects

Disparities in diabetes care: role of the patient's socio-demographic characteristics

<p>Abstract</p> <p>Background</p> <p>The commitment to promoting equity in health is derived from the notion that all human beings have the right to the best attainable health. However, disparities in health care are well-documented. The objectives were to explore disparities in diabetes prevalence, care and control among diabetic patients. The study was conducted by Maccabi Healthcare Services (MHS), an Israeli HMO (health care plan).</p> <p>Methods</p> <p>Retrospective study. The dependent variables were diabetes prevalence, uptake of follow-up examinations, and disease control. The independent variables were socio-economic rank (SER), ethnicity (Arab vs non Arab), supplementary voluntary health insurance (SVHI), and immigration from Former Soviet Union (FSU) countries. Chi Square and Logistic Regression Models were estimated.</p> <p>Results</p> <p>We analyzed 74,953 diabetes patients. Diabetes was more prevalent in males, lower SER patients, Arabs, immigrants and owners of SVHI. Optimal follow up was more frequent among females, lower SERs patients, non Arabs, immigrants and SVHI owners. Patients who were female, had higher SERs, non Arabs, immigrants and SVHI owners achieved better control of the disease. The multivariate analysis revealed significant associations between <it>optimal follow up </it>and age, gender (males), SER (Ranks 1-10), Arabs and SVHI (OR 1.02, 0.95, 1.15, 0.85 and 1.31, respectively); <it>poor diabetes control </it>(HbA1C > 9 gr%) was significantly associated with age, gender (males), Arabs, immigrants, SER (Ranks1-10) and SVHI (OR 0.96, 1.26, 1.38, 0.72, 1.37 and 0.57, respectively); significant associations with <it>LDL control </it>(< 100 gr%) were revealed for age, gender (males) and SVHI (OR 1.02, 1.30 and 1.44, respectively).</p> <p>Conclusion</p> <p>Disparities in diabetes prevalence, care and control were revealed according to population sub-group. MHS has recently established a comprehensive strategy and action plan, aimed to reduce disparities among members of low socioeconomic rank and Arab ethnicity, sub-groups identified in our study as being at risk for less favorable health outcomes.</p