Complexity of Strong Implementability

We consider the question of implementability of a social choice function in a classical setting where the preferences of finitely many selfish individuals with private information have to be aggregated towards a social choice. This is one of the central questions in mechanism design. If the concept of weak implementation is considered, the Revelation Principle states that one can restrict attention to truthful implementations and direct revelation mechanisms, which implies that implementability of a social choice function is easy to check. For the concept of strong implementation, however, the Revelation Principle becomes invalid, and the complexity of deciding whether a given social choice function is strongly implementable has been open so far. In this paper, we show by using methods from polyhedral theory that strong implementability of a social choice function can be decided in polynomial space and that each of the payments needed for strong implementation can always be chosen to be of polynomial encoding length. Moreover, we show that strong implementability of a social choice function involving only a single selfish individual can be decided in polynomial time via linear programming

Distribution of copper, cobalt and nickel in ores and host-rocks, Ingladhal, Karnataka, India

Stratiform quartz-sulphide lodes in Ingladhal occur in a typical Precambrian green-stone-belt environment comprising metabasalts, tuff, chert and cherty iron-sulphide formation. Unusually high cobalt contents of metavolcanics and of sulphide minerals in orebodies suggest a consanguinity between ores and rocks. 90% of total nickel, 70% of total cobalt but only 30% of total copper in rocks occur in silicate phases and thus indicate an early separation of copper from cobalt and nickel. Unusually high non-sulphide copper in barren bedded cherts implies availability of Cu-rich solution prior to their lithification. Pyrite in sediments, in volcanics, and in orebodies is characterized by a distinctive pattern of Co-Ni distribution in each case. Partitioning of Co and Ni between coexisting sulphide pairs is complex, but gross equilibrium is indicated. Very high trace metal content of orebody pyrite sharply contrasts with very low such values in pyrite from adjacent sediments and points to a higher temperature of formation of orebodies

Geothermometry based on fractionation of Mn and Cd between coexisting sphalerite and galena from some carbonate-hosted sulfide deposits in India

Geothermometry based on the fractionation of Mn and Cd between coexisting sphalerite and galena from concordantly banded, strata-bound ores and younger vein ores of Rajpura-Dariba, Zawar, and Bandalamottu has been attempted. Different fractionation trends for the banded and vein ores in the same deposit at Rajpura-Dariba indicate different thermal regimes of final equilibration for the two varieties of ores. In contrast, a single trend incorporating both types of ores is suggestive of isothermal conditions of final equilibration for the banded and vein ores at Zawar. Unrealistically high temperatures obtained for the vein ores of Bandalamottu suggest equilibrium in the sphalerite-galena aggregates of this deposit was not attained. Thermometric data from Mn and Cd fractionation are compared with other independent geothermometric determinations obtained from fluid inclusion homogenization studies and based on phase equilibria. It has been found that, in general, the Cd-fractionation temperature (TCd) is a more reliable geothermometer than the Mn-fractionation temperature (TMn). This presumably may be due to the susceptibility of aqueous Mn species to subtle changes in fo2 in the ore fluid and consequent heterogeneity in Mn concentration in sphalerite, thus affecting the distribution coefficient. The investigation also suggests that TCd becomes increasingly more dependable when the ores are metamorphosed and reequilibrated at higher grades of metamorphism

Role of methylation on the thermochemistry of alkali metal cation complexes of amino acids: N-methyl proline

pre-printQuantitative thermodynamic information is obtained from the study of the gasphase interactions of the alkali metal cation complexes of N-methyl proline (NMP) with Xe using a guided ion beam tandem mass spectrometer (GIBMS). Absolute bond dissociation energies (BDEs) of M+ = Li+, Na+, K+, and Rb+ to NMP are determined experimentally from threshold collision-induced dissociation (TCID) measurements of the M+(NMP) complexes. Analysis of their kinetic energy cross sections provide the 0 K bond enthalpies after accounting for unimolecular decay rates, internal energy of reactant ions, and multiple ion-molecule collisions. Quantum chemical calculations of the M+(NMP) BDEs are found to be in good agreement with the experimental values, establishing that the zwitterionic form is the lowest energy structure for all the metal ion complexes. Compared to M+(Pro) BDEs, the metal binding in these zwitterions is slightly enhanced by the CH3 group on the ring nitrogen, presumably a result of an inductive effect and its higher polarizability. More profound consequences of the methyl group emerge in the charge-solvated conformers calculated for M+(NMP) where it directs multiple conformations of the pyrrolidine ring. This is unlike the ring puckering phenomenon seen in M+(Pro) complexes, where fewer conformations are found, apparently because inversion at the nitrogen center is more facile

Theoretical investigation and reinterpretation of the decomposition of lithiated proline and N-Methyl Proline

pre-printLithium cation complexes of proline (Pro) and N-methyl proline (NMP) have been collisionally activated with xenon in a guided ion beam tandem mass spectrometer (GIBMS). In addition to the loss of the intact ligand, Pro and NMP, we observed two prominent fragmentation pathways involving the loss of (CO + LiOH) and (CO + H2O). Quantum chemical calculations at the B3LYP/6-311+G(d,p) level are used to explore the reaction mechanisms of these Li+(Pro) and Li+(NMP) fragmentations. Complete potential energy surfaces including all intermediates and transition states are elucidated for the two fragmentation processes in both systems. Theoretical molecular parameters for the rate-limiting transition states are then used to analyze the experimental data. The experimental threshold energies are compared with single point energies calculated at six different levels of theory. Reasonable agreement between experiment and some levels of theory indicate that loss of the intact amino acid competes with the loss of CO over a tight transition state in both Li+(Pro) and Li+(NMP) systems. Once CO is lost, efficient loss of H2O can occur at lower or comparable energy and is followed at somewhat higher energies by loss of LiOH, both proceeding by loose transition states. Overall, we find that MP2(full)/6-311+G(2d,2p) gives the best agreement with the experimental threshold energies and the qualitative characteristics of the competing reactions. This study refines the bond energy of Li+ to Pro by considering competition with CO loss and lowers the value previously published by 24 12 kJ/mol, with methylation of proline increasing the bond energy to Li+ by 9 15 kJ/mol

Healing Multiculturalism: Middle-Ground Liberal Forgiveness in a Diverse Public Realm

This article examines debates about political forgiveness in liberal, pluralist societies. Although the concept of forgiveness is not usually taken up by liberals, I outline a plausible conception by exploring two recent approaches. The first, ‘unattached articulation’, concept requires no real emotional change on the forgiver’s part, but rather a form of civic restraint. In contrast, the second version highlights a strong form of empathy for perpetrators. In spite of their advantages, each concept proves too extreme. The problems are revealed by focusing on the case of the Harkis, who fought for the French during the Algerian war. Often still marginalised in French society, their case helps to highlight the conceivability of a ‘middle-ground’ or moderate concept of political forgiveness. Its core rests on the forgiver’s care for the social world. While this concept brings considerable challenges also, and is not inevitable in any particular case, it entails a more plausible combination of emotional and rational shifts in the forgiver’s world-view. Although the article does not recommend forgiveness by any person or group, it observes, recalling Arendt’s idea of amor mundi or ‘love of the world’, that political forgiveness may sustain a viable connection between diverse citizens’ public and non-public lives

Antimicrobial host defence peptides: functions and clinical potential

Cationic host defence peptides (CHDP), also known as antimicrobial peptides, are naturally occurring peptides that can combat infections through their direct microbicidal properties and/or by influencing the host's immune responses. The unique ability of CHDP to control infections as well as resolve harmful inflammation has generated interest in harnessing the properties of these peptides to develop new therapies for infectious diseases, chronic inflammatory disorders and wound healing. Various strategies have been used to design synthetic optimized peptides, with negligible toxicity. Here, we focus on the progress made in understanding the scope of functions of CHDP and the emerging potential clinical applications of CHDP-based therapies

The potential for immunoglobulins and host defense peptides (HDPs) to reduce the use of antibiotics in animal production

Abstract Innate defense mechanisms are aimed at quickly containing and removing infectious microorganisms and involve local stromal and immune cell activation, neutrophil recruitment and activation and the induction of host defense peptides (defensins and cathelicidins), acute phase proteins and complement activation. As an alternative to antibiotics, innate immune mechanisms are highly relevant as they offer rapid general ways to, at least partially, protect against infections and enable the build-up of a sufficient adaptive immune response. This review describes two classes of promising alternatives to antibiotics based on components of the innate host defense. First we describe immunoglobulins applied to mimic the way in which they work in the newborn as locally acting broadly active defense molecules enforcing innate immunity barriers. Secondly, the potential of host defense peptides with different modes of action, used directly, induced in situ or used as vaccine adjuvants is described

Side Chain Hydrophobicity Modulates Therapeutic Activity and Membrane Selectivity of Antimicrobial Peptide Mastoparan-X

The discovery of new anti-infective compounds is stagnating and multi-resistant bacteria continue to emerge, threatening to end the "antibiotic era". Antimicrobial peptides (AMPs) and lipo-peptides such as daptomycin offer themselves as a new potential class of antibiotics; however, further optimization is needed if AMPs are to find broad use as antibiotics. In the present work, eight analogues of mastoparan-X (MPX) were investigated, having side chain modifications in position 1, 8 and 14 to modulate peptide hydrophobicity. The self-association properties of the peptides were characterized, and the peptide-membrane interactions in model membranes were compared with the bactericidal and haemolytic properties. Alanine substitution at position 1 and 14 resulted in higher target selectivity (red blood cells versus bacteria), but also decreased bactericidal potency. For these analogues, the gain in target selectivity correlated to biophysical parameters showing an increased effective charge and reduction in the partitioning coefficient for membrane insertion. Introduction of an unnatural amino acid, with an octyl side chain by amino acid substitution, at positions 1, 8 and 14 resulted in increased bactericidal potency at the expense of radically reduced membrane target selectivity. Overall, optimized membrane selectivity or bactericidal potency was achieved by changes in side chain hydrophobicity of MPX. However, enhanced potency was achieved at the expense of selectivity and vice versa in all cases

Robust tests for time-invariant individual heterogeneity versus dynamic state dependence

We derive tests for persistent effects in a general linear dynamic panel data context. Two sources of persistent behavior are considered: time-invariant unobserved factors (captured by an individual random effect) and dynamic persistence or “state dependence” (captured by autoregressive behavior). We will use a maximum likelihood framework to derive a family of tests that help researchers learn whether persistence is due to individual heterogeneity, dynamic effect, or both. The proposed tests have power only in the direction they are designed to perform, that is, they are locally robust to the presence of alternative sources of persistence, and consequently, are able to identify which source of persistence is active. A Monte Carlo experiment is implemented to explore the finite sample performance of the proposed procedures. The tests are applied to a panel data series of real GDP growth for the period 1960–2005