We extend the Main Theorem of Aschbacher and Smith on Quillen's Conjecture from p>5 to the remaining odd primes p = 3,5. In the process, we develop further combinatorial and homotopical methods for studying the poset of nontrivial elementary abelian p-subgroups of a finite group. The techniques lead to a number of further results on the Conjecture, often reducing dependence on the CFSG; in particular, we also provide some partial results toward the case of p=2.

We generalize an earlier result of Segev, which shows that some component in a minimal counterexample to Quillen's conjecture must admit an outer automorphism. We show in fact that every component must admit an outer automorphism. Thus we transform his restriction-result on components to an elimination-result: namely one which excludes any component which does not admit an outer automorphism. Indeed we show that the outer automorphisms admitted must include p-outers: that is, outer automorphisms of order divisible by p. This gives stronger, concrete eliminations: for example if p is odd, it eliminates sporadic and alternating components—thus reducing to Lie-type components (and typically forcing p-outers of field type). For p=2, we obtain similar but less restrictive results. We also provide some tools to help eliminate suitable components that do admit p-outers in a minimal counterexample.

BACKGROUND:Necrotizing enterocolitis (NEC) persists as the most common and serious gastrointestinal disorder among premature infants. Lactococcus lactis (LL), a lactic acid producing bacteria commonly found in buttermilk and cheese products, has several unique properties making it an ideal probiotic for neonates. We evaluated if the probiotic LL prevents development of NEC in a preterm rabbit model with Cronobacter sakazakii (CS).METHODS:Two-day preterm New Zealand white rabbit pups were randomly assigned to three diets: control (no additives), CS, and CS+LL. Pups were gavage fed and given daily oral ranitidine and indomethacin. Anal blockage was performed using tissue adhesive. Subjects were sacrificed on day four, with tissue from distal ileum and proximal colon graded for NEC by a pediatric pathologist blinded to group assignments. Outcomes were compared using Fisher's exact test.RESULTS:All pups in the control group survived to sacrifice and none developed NEC. Survival was 26% higher (p = 0.03) and incidence of NEC 51% less (P < 0.001) in CS+LL group compared to CS group. Of the pups that developed NEC, all pups in the CS+LL group had Grade 1 NEC, while one-third of pups in the CS group developed Grades 2-4 NEC.CONCLUSIONS:In the presence of CS, LL is protective against development of NEC in a preterm rabbit model. Future studies are needed that evaluate utilization of prophylactic probiotics in the neonatal intensive care unit to determine if this intervention can successfully decrease rates of NEC in preterm infants.

This is a brief survey of the research accomplishments of Bob Griess, focusing on the work primarily related to simple groups and their classification. It does not attempt to also cover Bob's many contributions to the theory of vertex operator algebras. (This is only because I am unqualified to survey that VOA material.)

This paper provides a theory of debt and hedging based on human capital. We distinguish human capital from physical capital in two ways: (1) human capital is inalienable and can exercise a one-sided option to leave the firm and (2) human capital is not perfectly replaceable. We show that a firm may reach the first best solution while issuing debt or equity to outsiders provided that either the insiders receive a senior claim or that the firm hedges. We then show that given asymmetric information concerning costs the only viable solution has the firm issuing debt to outsiders and hedging.

We investigate the relation between derivatives use and corporations’ cost of equity capital. Using a large sample of non-financial firms, we compute and analyze (i) the relative cost of equity of firms that use derivatives and those that do not; and (ii) the change in cost of equity experienced by firms initiating derivatives programs. We find that the cost of equity of derivatives users is lower than non-users by 24–78 basis points. Our results are robust to specifications that account for potential endogeneity related to a firm’s derivatives use and capital structure decisions. We further find that the reduction in the cost of equity is attributable to both lower market beta and SMB beta, suggesting that firms use derivatives to reduce their financial distress risk and that this distress risk has a systematic component that is priced in the market. Finally, the observed reductions in the cost of equity tend to be largest for smaller firms and for firms utilizing currency and interest rate derivatives.

This article provides a simple equilibrium model of a futures market. Since the futures market is a zero sum game, some firms will, in equilibrium, end up being 'speculators' who bet against 'hedgers'. We show it is firms that have high initial capital and/or poor production opportunities that are the most likely candidates to bet against the hedgers. In equilibrium, these groups earn a premium in order to provide this insurance so that speculating increases value. We also provide some results that imply an inverted U shaped relationship between trading volume and the level of futures prices. Empirical evidence from the SP futures contract provides strong empirical support for this theoretical result.

A survey of parts of the research area of “subgroup complexes”—which combines techniques from finite group theory, algebraic topology, and combinatorics. The exposition emphasizes the historical development, from the particular viewpoint of applications to simple groups and their geometries. The foundations are provided by the work of Tits on buildings, and of Brown and Quillen on simplicial complexes of p-subgroups of a group. The discussion continues through some relatively recent theoretical contributions from homotopy theory and from the p-local structure of simple groups; these improvements have made possible a joint work of Benson and Smith, which provides for each of the 26 sporadic simple groups a “small, simplex” decomposition of its mod 2 group cohomology. This is a more extended written version of a keynote talk delivered at the Midlands regional meeting of the London Mathematical Society, at the University of Birmingham on 18 May 2005—in conjunction with the subsequent workshop on “Fusion systems, representation theory, and groups”.

In this paper we theoretically and empirically examine the interaction between hedging, financing, and investment decisions. A simple equilibrium model with costly financial distress suggests that as firms become more efficient at risky investments vis a vis low risk investments, they will borrow less, invest more in risky assets, and hedge more. The model also predicts a positive relationship between hedging and leverage – a result consistent with debt capacity arguments. We test the model empirically using a simultaneous equations framework to investigate the determinants of firm-level hedging, financing and investing decisions. The results strongly support the hypothesis that the hedging, financing and investment decisions are jointly determined. In addition, we find strong support for the central hypothesis that firms more efficient investing in risky technologies more aggressively hedge and use less debt financing in order to maximize their comparative advantage.

Manuscript Type: EmpiricalResearch Question/Issue: We examine the relationship of concentration of shareholdings with the number of financial analysts following a firm to see if concentrated shareholders substitute for the monitoring activities of analysts.Research Findings/Results: Using a clean ownership dataset with a sample of 3,115 firm-year observations for U.S. firms and regression techniques that address any potential endogeneity, we find that analyst following is negatively related to the concentration of outsider and insider shareholdings. We find similar relations for changes in analyst following and changes in ownership concentration.Theoretical Implications: Our results support the argument that an outsider with a larger stake in a firm is more likely to produce its own in-house information for the monitoring of the firm's managers and avoid both the cost and moral hazard problems associated with analysts. The results also support the argument that if senior managers hold large stakes in the firm, there is a greater likelihood that managerial incentives will be aligned with those of other shareholders.Practical Implications: We contend that there is a governance substitution effect, with concentrated shareholders substituting for the monitoring activities of analysts. Our results are consistent with the opinion that regulators need not fear large shareholders. This is especially applicable to large outside shareholders as we find that the economic effect of concentrated outsider shareholdings is quite strong and greater than that of concentrated insider shareholdings.

PAK1 is a member of the p21-activated kinase (PAK) family of serine/threonine kinases that are activated by the Rho GTPases Rac and Cdc42, and are implicated in regulating morphological polarity, cell migration and adhesion. Here we investigate the function of PAK1 in cell motility using macrophages derived from PAK1-null mice. We show that CSF1, a macrophage chemoattractant, transiently stimulates PAK1 and MAPK activation, and that MAPK activation is reduced in PAK1–/– macrophages. PAK1 regulates the dynamics of lamellipodium extension as cells spread in response to adhesion but is not essential for macrophage migration or chemotaxis towards CSF1. Following adhesion, PAK1–/– macrophages spread more rapidly and have more lamellipodia than wild-type cells; however, these lamellipodia were less stable than those in wild-type macrophages. ERK1/2 activity was reduced in PAK1–/– macrophages during adhesion, and inhibition of ERK1/2 activation in wild-type macrophages was sufficient to increase the spread area and mimic the lamellipodial dynamics of PAK1–/– macrophages. Together, these data indicate that PAK1 signals via ERK1/2 to regulate lamellipodial stability.

We empirically investigate the interactions among hedging, financing and investment decisions. We argue that the way in which hedging affects a firm's financing and investing decisions differs for firms with different growth opportunities. We find that high growth firms increase their investment, but not leverage, by hedging. However, we also find that firms with few investment opportunities use derivatives to increase their leverage.

Podosomes are actin-rich adhesive foci found in several cell types, including macrophages. They have a core containing actin and actin-binding proteins and a peripheral ring of integrins and associated proteins. We show that podosomes are abundant in polarized mouse bone marrow-derived macrophages (BMM) and are found primarily in lamellae. We investigated the effects of CSF-1, which induces membrane ruffling, cell spreading, and subsequent polarization and migration, on podosome formation. CSF-1 induces a transient increase in podosome number and enhances the formation of circular arrays of podosomes. Conversely, CSF-1 withdrawal leads to a reduction in podosomes and a decrease in polarized cells. The PI 3-kinase inhibitor LY294002 induces loss of podosomes together with rapid retraction of lamellae and loss of polarity. Our results indicate that CSF-1 acts via PI 3-kinase to enhance podosome assembly and that this is linked to macrophage polarization.

Plant-made oral vaccines have the potential to overcome many of the limitations of traditional vaccines. Here we report on progress towards a lettuce-made measles vaccine. Lettuce is a palatable species which exhibits rapid growth in contained hydroponic systems and produces negligible quantities of toxins. Measles virus hemagglutinin (MV-H) protein was successfully expressed in transgenic lettuce and found to be immunogenic in mice. Lettuce extracts containing MV-H protein induced MV neutralising antibodies following intraperitoneal injection and intranasal inoculation of mice. Using a sequential prime-boost strategy in which mice were vaccinated with MV-H DNA followed by an orally delivered freeze–dried MV-H lettuce formulation a 10-fold increased in MV-specific IgG titers was observed relative to mice vaccinated with control lettuce formulations (p=0.05). MV-H protein was stable in freeze–dried lettuce for up to 13 months at room temperature, and survived at least a week at temperatures as high as 50°C. This research represents a significant step towards the development of measles vaccine formulation that is effective, temperature-stable, easy to administer in a resource-poor setting and amenable to large scale manufacture.

Rac GTPases are believed to contribute to migration in leukocytes by transducing signals from cell surface receptors to the actin and microtubule cytoskeletons. Mammals have three closely related Rac isoforms, Rac1, Rac2 and Rac3, and it is widely assumed that cell migration requires the activity of these Rac GTPases. We have previously shown that Rac1-null mouse macrophages have altered cell shape and reduced membrane ruffling but normal migration speed. Here we investigate the behaviour of macrophages lacking Rac2 (Rac2–/–) or Rac1 and Rac2 (Rac1/2–/–). Rac2–/– macrophages have reduced F-actin levels and lack podosomes, which are integrin-based adhesion sites, and their migration speed is similar to or slightly slower than wild-type macrophages, depending on the substrate. Unexpectedly, Rac1/2–/– macrophages, which do not express Rac1, Rac2 or Rac3, migrate at a similar speed to wild-type macrophages on a variety of substrates and perform chemotaxis normally, although their morphology and mode of migration is altered. However, Rac1–/– and Rac1/2–/– but not Rac2–/– macrophages are impaired in their ability to invade through Matrigel. Together, these data show that Rac1 and Rac2 have distinct roles in regulating cell morphology, migration and invasion, but are not essential for macrophage migration or chemotaxis.

Mapping invasive plant species in aquatic and terrestrial ecosystems helps to understand the causes of their progression, manage some of their negative consequences, and control them. In recent years, a variety of new remote-sensing techniques, like Derivative Spectral Analysis (DSA) of hyperspectral data, have been developed to facilitate this mapping. A number of questions related to these techniques remain to be addressed. This article attempts to answer one of these questions: Is the application of DSA optimal at certain times of the year? Field radiometric data gathered weekly during the summer of 1999 at selected field sites in upstate New York, populated with purple loosestrife (Lythrum salicaria L.), common reed (Phragmites australis (Cav.)) and cattail (Typha L.) are analyzed using DSA to differentiate among plant community types. First, second and higher-order derivatives of the reflectance spectra of nine field plots, varying in plant composition, are calculated and analyzed in detail to identify spectral ranges in which one or more community types have distinguishing features. On the basis of the occurrence and extent of these spectral ranges, experimental observations suggest that a satisfactory differentiation among community types was feasible on 30 August, when plants experienced characteristic phenological changes (transition from flowers to seed heads). Generally, dates in August appear optimal from the point of view of species differentiability and could be selected for image acquisitions. This observation, as well as the methodology adopted in this article, should provide a firm basis for the acquisition of hyperspectral imagery and for mapping the targeted species over a broad range of spatial scales.

We empirically investigate the interactions among hedging, financing, and investment decisions. We argue that the way in which hedging affects a firm's financing and investing decisions differs for firms with different growth opportunities. We find that high growth firms increase their investment, but not leverage, by hedging. However, we also find that firms with few investment opportunities use derivatives to increase their leverage.

Millions of people live in areas where infectious diseases, such as measles, are endemic and resources are scarce. Heat-stable vaccines that are delivered orally will greatly enhance vaccination programs in these areas. A stumbling block in the development of oral vaccines is the availability of safe and effective mucosal adjuvants, especially for use with subunit vaccines. The experiments presented here examine the ability of CTB/CT, LT(R192G) and crude Quillaja saponin extracts to stimulate MV-specific immune responses in mice, following oral immunisation with plant-made measles virus hemagglutinin (MV-H) protein. LT(R192G) and crude saponin extracts both functioned as potent mucosal adjuvants when ad-mixed with plant-made MV-H protein, and were more effective than CTB/CT. MV-H protein supplemented with saponin extract induced the strongest MV-specific responses, in the greatest number of mice. Crude saponins are routinely used by the food and beverage industry at concentrations greater than those required for adjuvanticity, and as such, they have a better safety profile than bacterial enterotoxins. This study demonstrates their potential as adjuvants for use with oral plant-made vaccines.