Non-Markovian Memory Strength Bounds Quantum Process Recoverability

Generic non-Markovian quantum processes have infinitely long memory, implying an exact description that grows exponentially in complexity with observation time. Here, we present a finite memory ansatz that approximates (or recovers) the true process with errors bounded by the strength of the non-Markovian memory. The introduced memory strength is an operational quantity and depends on the way the process is probed. Remarkably, the recovery error is bounded by the smallest memory strength over all possible probing methods. This allows for an unambiguous and efficient description of non-Markovian phenomena, enabling compression and recovery techniques pivotal to near-term technologies. We highlight the implications of our results by analyzing an exactly solvable model to show that memory truncation is possible even in a highly non-Markovian regime.Comment: 8 pages, 7 pages of appendices, 5 figures. Close to the published versio

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Is desire for social relationships mediated by the serotonergic system in the prefrontal cortex? An [18F] setoperone PET study

Social behavior and desire for social relationships have been independently linked to the serotonergic system, the prefrontal cortex, especially the orbitofrontal cortex (OFC), and the anterior cingulate cortex (ACC). The goal of this study was to explore the role of serotonin 5HT2A receptors in these brain regions in forming and maintaining close interpersonal relationships. Twenty-four healthy subjects completed the Temperament and Character Inventory (TCI) prior to undergoing [18F]setoperone brain positron emission tomography (PET) to measure serotonin 5HT2A receptor availability within the OFC (BA 11 and 47) and ACC (BA 32). We explored the relationship between desire for social relationships, as measured by the TCI reward dependence (RD) scale, and 5HT2A receptor non-displaceable binding potential (BPnd) in these regions. Scores of RD were negatively correlated with 5HT2A BPnd in the ACC (BA 32, r = –.528, p = .012) and OFC (BA 11, r = –.489, p = .021; BA 47, r = –.501, p = .017). These correlations were corroborated by a voxel-wise analysis. These results suggest that the serotonergic system may have a regulatory effect on the OFC and ACC for establishing and maintaining social relationships.peer-reviewe

Induction of Metastatic Gastric Cancer by Peroxisome Proliferator-Activated Receptorδ Activation

Peroxisome proliferator-activated receptorδ (PPARδ) regulates a multiplicity of physiological processes associated with glucose and lipid metabolism, inflammation, and proliferation. One or more of these processes likely create risk factors associated with the ability of PPARδ agonists to promote tumorigenesis in some organs. In the present study, we describe a new gastric tumor mouse model that is dependent on the potent and highly selective PPARδ agonist GW501516 following carcinogen administration. The progression of gastric tumorigenesis was rapid as determined by magnetic resonance imaging and resulted in highly metastatic squamous cell carcinomas of the forestomach within two months. Tumorigenesis was associated with gene expression signatures indicative of cell adhesion, invasion, inflammation, and metabolism. Increased PPARδ expression in tumors correlated with increased PDK1, Akt, β-catenin, and S100A9 expression. The rapid development of metastatic gastric tumors in this model will be useful for evaluating preventive and therapeutic interventions in this disease

Single and Paired Point Defects in a 2D Wigner Crystal

Using the path-integral Monte Carlo method, we calculate the energy to form single and pair vacancies and interstitials in a two-dimensional Wigner crystal of electrons. We confirm that the lowest-lying energy defects of a 2D electron Wigner crystal are interstitials, with a creation energy roughly 2/3 that of a vacancy. The formation energy of the defects goes to zero near melting, suggesting that point defects might mediate the melting process. In addition, we find that the interaction between defects is strongly attractive, so that most defects will exist as bound pairs.Comment: 4 pages, 5 encapsulated figure