A Closed-Form Solution of the Multi-Period Portfolio Choice Problem for a Quadratic Utility Function

In the present paper, we derive a closed-form solution of the multi-period portfolio choice problem for a quadratic utility function with and without a riskless asset. All results are derived under weak conditions on the asset returns. No assumption on the correlation structure between different time points is needed and no assumption on the distribution is imposed. All expressions are presented in terms of the conditional mean vectors and the conditional covariance matrices. If the multivariate process of the asset returns is independent it is shown that in the case without a riskless asset the solution is presented as a sequence of optimal portfolio weights obtained by solving the single-period Markowitz optimization problem. The process dynamics are included only in the shape parameter of the utility function. If a riskless asset is present then the multi-period optimal portfolio weights are proportional to the single-period solutions multiplied by time-varying constants which are depending on the process dynamics. Remarkably, in the case of a portfolio selection with the tangency portfolio the multi-period solution coincides with the sequence of the simple-period solutions. Finally, we compare the suggested strategies with existing multi-period portfolio allocation methods for real data.Comment: 38 pages, 9 figures, 3 tables, changes: VAR(1)-CCC-GARCH(1,1) process dynamics and the analysis of increasing horizon are included in the simulation study, under revision in Annals of Operations Researc

A photoelectron spectroscopy study of the electronic structure evolution in CuInSe2-related compounds at changing copper content

Evolution of the valence-band structure at gradually increasing copper content has been analysed by x-ray photoelectron spectroscopy (XPS) in In2Se3, CuIn5Se8, CuIn3Se5, and CuInSe2 single crystals. A comparison of these spectra with calculated total and angular-momentum resolved density-of-states (DOS) revealed the main trends of this evolution. The formation of the theoretically predicted gap between the bonding and non-bonding states has been observed in both experimental XPS spectra and theoretical DOS

Burrowing Behavior of a Deposit Feeding Bivalve Predicts Change in Intertidal Ecosystem State

Behavior has a predictive power that is often underutilized as a tool for signaling ecological change. The burrowing behavior of the deposit feeding bivalve Macoma balthica reflects a typical food-safety trade-off. The choice to live close to the sediment surface comes at a risk of predation and is a decision made when predation danger, food intake rates or future fitness prospects are low. In parts of the Dutch Wadden Sea, Macoma populations declined by 90% in the late 1990s, in parallel with large-scale mechanical cockle-dredging activities. During this decline, the burrowing depth of Macoma became shallow and was correlated with the population decline in the following year, indicating that it forecasted population change. Recently, there has been a series of large recruitment events in Macoma. According to the food-safety trade-off, we expected that Macoma should now live deeper, and have a higher body condition. Indeed, we observed that Macoma now lives deeper and that living depth in a given year forecasted population growth in the next year, especially in individuals larger than 14 mm. As living depth and body condition were strongly correlated in individuals larger than 14 mm, larger Macoma could be living deeper to protect their reproductive assets. Our results confirmed that burrowing depth signals impending population change and, together with body condition, can provide an early warning signal of ecological change. We suggest that population recovery is being driven by improved intertidal habitat quality in the Dutch Wadden Sea, rather than by the proposed climate-change related effects. This shift in ecosystem state is suggested to include the recovery of diatom habitat in the top layer of the sediment after cockle-dredging ended

Electric-field-induced nematic-cholesteric transition and 3-D director structures in homeotropic cells

We study the phase diagram of director structures in cholesteric liquid crystals of negative dielectric anisotropy in homeotropic cells of thickness d which is smaller than the cholesteric pitch p. The basic control parameters are the frustration ratio d/p and the applied voltage U. Fluorescence Confocal Polarising Microscopy allows us to directly and unambiguously determine the 3-D director structures. The results are of importance for potential applications of the cholesteric structures, such as switchable gratings and eyewear with tunable transparency based.Comment: Will be published in Physical Review

Xenobiotic Metabolism in Mice Lacking the UDP-Glucuronosyltransferase 2 Family

UDP-Glucuronosyltransferases (UGTs) conjugate a glucuronyl group from glucuronic acid to a wide range of lipophilic substrates to form a hydrophilic glucuronide conjugate. The glucuronide generally has decreased bioactivity and increased water solubility to facilitate excretion. Glucuronidation represents an important detoxification pathway for both endogenous waste products and xenobiotics, including drugs and harmful industrial chemicals. Two clinically significant families of UGT enzymes are present in mammals: UGT1s and UGT2s. Although the two families are distinct in gene structure, studies using recombinant enzymes have shown considerable overlap in their ability to glucuronidate many substrates, often obscuring the relative importance of the two families in the clearance of particular substrates in vivo. To address this limitation, we have generated a mouse line, termed ΔUgt2, in which the entire Ugt2 gene family, extending over 609 kilobase pairs, is excised. This mouse line provides a means to determine the contributions of the two UGT families in vivo. We demonstrate the utility of these animals by defining for the first time the in vivo contributions of the UGT1 and UGT2 families to glucuronidation of the environmental estrogenic agent bisphenol A (BPA). The highest activity toward this chemical is reported for human and rodent UGT2 enzymes. Surprisingly, our studies using the ΔUgt2 mice demonstrate that, while both UGT1 and UGT2 isoforms can conjugate BPA, clearance is largely dependent on UGT1s

Dendritic Cells Activate and Mature after Infection with Mycobacterium tuberculosis

<p>Abstract</p> <p>Background</p> <p>Dendritic cells (DCs) can take up an array of different antigens, including microorganisms which they can process and present more effectively than any other antigen presenting cell. However, whether the interaction between the human DC and <it>Mycobacterium tuberculosis </it>represents a defense mechanism by the invaded host, or helping the invader to evade the defense mechanism of the host is still not clearly understood.</p> <p>Findings</p> <p>To analyze the interactions between <it>M. tuberculosis </it>and immune cells, human peripheral blood monocyte-derived immature DCs were infected with <it>M. tuberculosis </it>H37Rv wild type strain and flow cytometry was used to analyse cell surface expression markers. The ability of the <it>M. tuberculosis </it>infected DC to induce T cell proliferation using 5 and 6-carboxyfluorescein diacetate succinimidyl ester (CFSE) dilution technique was also investigated. DCs were found to internalize the mycobacteria and show dose dependent infection and necrosis with different multiplicity of infection. Flow cytometry analysis of cell surface expression markers CD40, CD54, CD80, CD83, CD86 and HLA DR in infected DC revealed significant (p < 0.05) up regulation following infection with <it>M. tuberculosis </it>in comparison to immature DC with no stimulation. Lipopolysaccharide (LPS) from <it>Salmonella abortus equi</it>, a known DC maturation agent, was used as a positive control and showed a comparable up regulation of cell surface markers as observed with <it>M. tuberculosis </it>infected DC. It was revealed that the <it>M. tuberculosis </it>infected DC induced T cell proliferation.</p> <p>Conclusion</p> <p>These data clearly demonstrate that <it>M. tuberculosis </it>induces activation and maturation of human monocyte-derived immature DC as well as induces T cell proliferation <it>in vitro</it>.</p

Forces Sauces and Eggs for Soldiers: food, nostalgia, and the rehabilitation of the British military

This article identifies, and considers the political implications of, the association of the contemporary British military and British soldiers with nostalgia. This aspect of the discursive project of rehabilitating the British military post-Iraq has not hitherto been theorized. The article analyses a set of exemplifying texts, four military charity food brands (Eggs for Soldiers, Forces Sauces, Red Lion Foods, and Rare Tea Company Battle of Britain Tea) to ask how nostalgic rehabilitation of the British military unfolds at the intersections of militarization, commemoration, and post-2008 “conscience capitalism”. I outline how military charity food brands are a form of “conscience capitalism” through which the perpetuation of militarized logics are produced as a notionally apolitical social “cause”, rendered intelligible within the terms of existing commoditized discourses of post-2008 vintage nostalgia. I then ask what understandings of British soldiers and the British military are constituted within the discourse of nostalgic rehabilitation, and secondly what forms of commemoration are entailed. I argue that a nostalgic generalization of soldiers and the military nullifies the potential unruliness of individual soldiers and obscures the specifics of recent, controversial, wars. Secondly nostalgic civil–military engagement entails a commemorative logic in which forms of quasi-military service are brought into the most banal spaces of everyday civilian life

Overturning established chemoselectivities : selective reduction of arenes over malonates and cyanoacetates by photoactivated organic electron donors

The prevalence of metal-based reducing reagents, including metals, metal complexes, and metal salts, has produced an empirical order of reactivity that governs our approach to chemical synthesis. However, this reactivity may be influenced by stabilization of transition states, intermediates, and products through substrate-metal bonding. This article reports that in the absence of such stabilizing interactions, established chemoselectivities can be overthrown. Thus, photoactivation of the recently developed neutral organic superelectron donor 5 selectively reduces alkyl-substituted benzene rings in the presence of activated esters and nitriles, in direct contrast to metal-based reductions, opening a new perspective on reactivity. The altered outcomes arising from the organic electron donors are attributed to selective interactions between the neutral organic donors and the arene rings of the substrates