Time consistent discounting

A possibly immortal agent tries to maximise its summed discounted rewards over time, where discounting is used to avoid infinite utilities and encourage the agent to value current rewards more than future ones. Some commonly used discount functions lead to time-inconsistent behavior where the agent changes its plan over time. These inconsistencies can lead to very poor behavior. We generalise the usual discounted utility model to one where the discount function changes with the age of the agent. We then give a simple characterisation of time-(in)consistent discount functions and show the existence of a rational policy for an agent that knows its discount function is time-inconsistent

Social capital in Russian agricultural production co-operatives

When the Soviet kolkhozy and sovkhozy were converted, a large number of agricultural production co-operatives was created. Most of these co-operatives still exist in Russia and some of them have a strong market position, accounting for almost one-third of the aggregate volume produced by large farms. This study explores whether social capital might be the explanation for this relative success, i.e. that members support their co-operative because they trust their fellow members as well as the leadership. Interviews with co-operative members resulted in 1401 usable answers. The results from an ordered logit model indicate that social capital plays a partial role. Members who consider co-operatives to be an efficient business form value social ties to other members, even though the leadership does not enjoy much social capital

Weak Localization Effect in Superconductors by Radiation Damage

Large reductions of the superconducting transition temperature $T_{c}$ and the accompanying loss of the thermal electrical resistivity (electron-phonon interaction) due to radiation damage have been observed for several A15 compounds, Chevrel phase and Ternary superconductors, and $\rm{NbSe_{2}}$ in the high fluence regime. We examine these behaviors based on the recent theory of weak localization effect in superconductors. We find a good fitting to the experimental data. In particular, weak localization correction to the phonon-mediated interaction is derived from the density correlation function. It is shown that weak localization has a strong influence on both the phonon-mediated interaction and the electron-phonon interaction, which leads to the universal correlation of $T_{c}$ and resistance ratio.Comment: 16 pages plus 3 figures, revtex, 76 references, For more information, Plesse see http://www.fen.bilkent.edu.tr/~yjki

Partitioning the Heritability of Tourette Syndrome and Obsessive Compulsive Disorder Reveals Differences in Genetic Architecture

The direct estimation of heritability from genome-wide common variant data as implemented in the program Genome-wide Complex Trait Analysis (GCTA) has provided a means to quantify heritability attributable to all interrogated variants. We have quantified the variance in liability to disease explained

Discovery and functional prioritization of Parkinson's disease candidate genes from large-scale whole exome sequencing.

BACKGROUND: Whole-exome sequencing (WES) has been successful in identifying genes that cause familial Parkinson's disease (PD). However, until now this approach has not been deployed to study large cohorts of unrelated participants. To discover rare PD susceptibility variants, we performed WES in 1148 unrelated cases and 503 control participants. Candidate genes were subsequently validated for functions relevant to PD based on parallel RNA-interference (RNAi) screens in human cell culture and Drosophila and C. elegans models. RESULTS: Assuming autosomal recessive inheritance, we identify 27 genes that have homozygous or compound heterozygous loss-of-function variants in PD cases. Definitive replication and confirmation of these findings were hindered by potential heterogeneity and by the rarity of the implicated alleles. We therefore looked for potential genetic interactions with established PD mechanisms. Following RNAi-mediated knockdown, 15 of the genes modulated mitochondrial dynamics in human neuronal cultures and four candidates enhanced α-synuclein-induced neurodegeneration in Drosophila. Based on complementary analyses in independent human datasets, five functionally validated genes-GPATCH2L, UHRF1BP1L, PTPRH, ARSB, and VPS13C-also showed evidence consistent with genetic replication. CONCLUSIONS: By integrating human genetic and functional evidence, we identify several PD susceptibility gene candidates for further investigation. Our approach highlights a powerful experimental strategy with broad applicability for future studies of disorders with complex genetic etiologies

Para-infectious brain injury in COVID-19 persists at follow-up despite attenuated cytokine and autoantibody responses

To understand neurological complications of COVID-19 better both acutely and for recovery, we measured markers of brain injury, inflammatory mediators, and autoantibodies in 203 hospitalised participants; 111 with acute sera (1–11 days post-admission) and 92 convalescent sera (56 with COVID-19-associated neurological diagnoses). Here we show that compared to 60 uninfected controls, tTau, GFAP, NfL, and UCH-L1 are increased with COVID-19 infection at acute timepoints and NfL and GFAP are significantly higher in participants with neurological complications. Inflammatory mediators (IL-6, IL-12p40, HGF, M-CSF, CCL2, and IL-1RA) are associated with both altered consciousness and markers of brain injury. Autoantibodies are more common in COVID-19 than controls and some (including against MYL7, UCH-L1, and GRIN3B) are more frequent with altered consciousness. Additionally, convalescent participants with neurological complications show elevated GFAP and NfL, unrelated to attenuated systemic inflammatory mediators and to autoantibody responses. Overall, neurological complications of COVID-19 are associated with evidence of neuroglial injury in both acute and late disease and these correlate with dysregulated innate and adaptive immune responses acutely

CHARGE DENSITY WAVE PHASE TRANSITIONS OBSERVED BY X-RAY PHOTOEMISSION

Nous avons mesuré les énergies de liaison des niveaux 4f du Tantale dans TaS2, TaSe2 et Ta0,97Hf0,03S2 entre 14 K et 371 K avec la photoémission à rayon X (XPS). La présence d'onde de densité de charge (CDW's) a pour effet de produire des potentiels non équivalents aux différents sites des atomes Ta. Ceci entraîne le dédoublement des lignes 4f en XPS ; l'écartement est une mesure de l'amplitude de l'onde de densité de charge, et représente un paramètre d'ordre pour le système CDW-réseau. La forme des composants de l'émission XPS permet de déduire la configuration de la CDW vis-à-vis du réseau, et puisque les gradients de potentiels aux sites non équivalents des atomes Ta sont différents, la largeur des composants fournit une mesure de la nature dynamique du système CDW-réseau. Les résultats démontrent l'existence d'une fluctuation CDW dans la phase où il y a coïncidence entre le réseau et la CDW. Dans les cas où la coïncidence entre le réseau et la CDW est imparfaite, ou qu'il n'y en a pas, les CDW ne peuvent garder la cohérence à longue distance. Dans le 1 T Ta0,97Hf0,03S2, les atomes de Hafnium ont pour effet d'ancrer les CDW (qui ne sont pas en coïncidence avec le réseau) en domaines.X-ray photoemission (XPS) measurements of the binding energies of the Ta 4f core levels in TaS2, TaSe2, and Ta0.97Hf0.03S2 at temperatures between 14 K and 371 K are reported. The presence of charge density waves (CDW's) produces inequivalent potentials at different Ta sites which split the 4f XPS lines ; the splitting is a measure of the CDW amplitude and represents an order parameter for the CDW-lattice system. The form of the components of the split XPS lines allows the CDW-lattice configuration to be deduced, and since the potential gradients at inequivalent Ta sites are different, the unequal widths of the components yields a measure of thefluctuating nature of the CDW-lattice system. The results indicate the existence of CDW fluctuations in commensurate phases, and that in some incommensurate and quasi-commensurate phases the CDW's cannot maintain long range coherence. In 1 T-Ta0.97Hf0.03S2 the Hf impurities pin the incommensurate CDW's into domains