2,824 research outputs found

    Advisors and Asset Prices: A Model of the Origins of Bubbles

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    We develop a model of asset price bubbles based on the communication process between advisors and investors. Advisors are well-intentioned and want to maximize the welfare of their advisees (like a parent treats a child). But only some advisors understand the new technology (the tech-savvies); others do not and can only make a downward-biased recommendation (the old-fogies). While smart investors recognize the heterogeneity in advisors, naive ones mistakenly take whatever is said at face value. Tech-savvies inflate their forecasts to signal that they are not old-fogies, since more accurate information about their type improves the welfare of investors in the future. A bubble arises for a wide range of parameters, and its size is maximized when there is a mix of smart and naive investors in the economy. Our model suggests an alternative source for stock over-valuation in addition to investor overreaction to news and sell-side bias.

    5,11,17,23-Tetra-tert-butyl-25,26,27,28-tetra­propyn­yloxy-2,8,14,20-tetra­thia­calix[4]arene

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    The title compound [systematic name: 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetra­propyn­yloxy-2,8,14,20-tetra­thia­calix[4]arene], C52H56O4S4, is an alkyl­ated product bearing four propyne groups at the lower rim of a 5,11,17,23-tetra-tert-butyl-tetrathia­calix[4]arene. The mol­ecule is located on a crystallographic twofold rotation axis, running through two S atoms and perpendicular to the long axis of the mol­ecule. The four propyne groups, located in an alternate fashion above and below the mean plane of the four S atoms, are almost parallel to the calixarene long axis. The dihedral angle between the two crystallographically independent benzene rings is 86.77 (14)°. Two tert-butyl groups are disordered over two positions with site occupancies of 0.59 (2) and 0.41 (2)

    Pharmacokinetic/Pharmacodynamic Correlation of Cefquinome Against Experimental Catheter-Associated Biofilm Infection Due to Staphylococcus aureus.

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    Biofilm formations play an important role in Staphylococcus aureus pathogenesis and contribute to antibiotic treatment failures in biofilm-associated infections. The aim of this study was to evaluate the pharmacokinetic/pharmacodynamic (PK/PD) profiles of cefquinome against an experimental catheter-related biofilm model due to S. aureus, including three clinical isolates and one non-clinical isolate. The minimal inhibitory concentration (MIC), minimal biofilm inhibitory concentration (MBIC), biofilm bactericidal concentration (BBC), minimal biofilm eradication concentration (MBEC) and biofilm prevention concentration (BPC) and in vitro time-kill curves of cefquinome were studied in both planktonic and biofilm cells of study S. aureus strains. The in vivo post-antibiotic effects (PAEs), PK profiles and efficacy of cefquinome were performed in the catheter-related biofilm infection model in murine. A sigmoid E max model was utilized to determine the PK/PD index that best described the dose-response profiles in the model. The MICs and MBICs of cefquinome for the four S. aureus strains were 0.5 and 16 μg/mL, respectively. The BBCs (32-64 μg/mL) and MBECs (64-256 μg/mL) of these study strains were much higher than their corresponding BPC values (1-2 μg/mL). Cefquinome showed time-dependent killing both on planktonic and biofilm cells, but produced much shorter PAEs in biofilm infections. The best-correlated PK/PD parameters of cefquinome for planktonic and biofilm cells were the duration of time that the free drug level exceeded the MIC (fT > MIC, R (2) = 96.2%) and the MBIC (fT > MBIC, R (2) = 94.7%), respectively. In addition, the AUC24h/MBIC of cefquinome also significantly correlated with the anti-biofilm outcome in this model (R (2) = 93.1%). The values of AUC24h/MBIC for biofilm-static and 1-log10-unit biofilm-cidal activity were 22.8 and 35.6 h; respectively. These results indicate that the PK/PD profiles of cefquinome could be used as valuable guidance for effective dosing regimens treating S. aureus biofilm-related infections

    High photo-excited carrier multiplication by charged InAs dots in AlAs/GaAs/AlAs resonant tunneling diode

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    We present an approach for the highly sensitive photon detection based on the quantum dots (QDs) operating at temperature of 77K. The detection structure is based on an AlAs/GaAs/AlAs double barrier resonant tunneling diode combined with a layer of self-assembled InAs QDs (QD-RTD). A photon rate of 115 photons per second had induced 10nA photocurrent in this structure, corresponding to the photo-excited carrier multiplication factor of 10^7. This high multiplication factor is achieved by the quantum dot induced memory effect and the resonant tunneling tuning effect of QD-RTD structure.Comment: 10 pages,5 figures. Submitted to Applied Physics Letter

    Development and evaluation of a Traditional Chinese Medicine syndrome questionnaire for measuring sub-optimal health status in China

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    AbstractObjectiveSub-optimal health status (SHS), in which a person's mind and body exists in a low-quality state of being between disease and health, has become a public health problem that cannot be ignored in China. SHS measurement presents a challenge to the academic fields. We developed and evaluated a questionnaire from the perspective of traditional Chinese medicine (TCM) that embodies the features of TCM syndrome diagnosis for measuring SHS in China.MethodsThe construction of the theoretical framework of the questionnaire was based on a literature review, an expert questionnaire survey and group interviews. The subscales and questionnaire items were screened through a pilot study using statistical means and qualitative analysis. Reliability tests that were used included test-retest reliability, Cronbach's α coefficient, split-half reliability; validity tests included content validity, criterion validity, discrimination validity and construct validity.ResultsThe final questionnaire, the SHSQ-50, included 50 five-class quantifiable items that encompassed nine subscales: liver stagnation syndrome, liver-Qi deficiency syndrome, spleen-Qi deficiency syndrome, liver-fire syndrome, heart-fire syndrome, stomach-fire syndrome, heart-Qi deficiency syndrome, lung-Qi deficiency syndrome and dampness syndrome. Questionnaires were completed by 268 of the 288 SHS subjects (93.0%) and by 86 of the 94 healthy subjects (91.5%). The Cronbach α coefficients, split-half coefficients and stability coefficients ranged from 0.70 to 0.95, 0.67 to 0.87 and 0.88 to 0.98, respectively, for the overall scores and subscales. The Wilcoxon rank test showed statistically significant differences in the subscales and overall scores between the SHS group and the healthy group (P<0.01). Twelve factors with an eigenvalue greater than one were extracted by factor analysis and merged into nine factors, for which the cumulative contribution rate was 63.63%. The nine factors were corresponded to the overall structure of the questionnaire.ConclusionThe SHSQ-50 is a reliable and valid instrument for measuring TCM syndrome diagnosis of SHS in China
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