1,726 research outputs found
CAPACITIES AND PROBABILISTIC BELIEFS: A PRECARIOUS COEXISTENCE
This paper raises the problem of how to define revealed probabilistic beliefs in the context of the capacity/Choquet Expected Utility model. At the center of the analysis is a decision-theoretically axiomatized definition of ""revealed unambiguous events."" The definition is shown to impose surprisingly strong restrictions on the underlying capacity and on the set of unambiguous events; in particular, the latter is always an algebra. Alternative weaker definitions violate even minimal criteria of adequacy. Rather than finding fault with the proposed definition, we argue that our results indicate that the CEU model is epistemically restrictive, and point out that analogous problems do not arise within the Maximin Expected Utility model.
EQUITY, BONDS, GROWTH AND INFLATION IN A QUADRATIC INFINITE HORIZON ECONOMY
This paper exhibits a class of infinite-horizon economies with incomplete markets (GEI) for which the equilibrium can be explicitly derived. We show that if agents have preference orderings represented by expected discounted quadratic utilities and if their endowments are tradable, then the equilibrium consumption and welfare of agents can be expressed as a function of the least variable income stream (LVI) obtainable by trading on the financial markets. If in addition the economy has a Markov structure, then the LVI can be calculated. The model is used to study the behavior of agents on the equity and bond markets in an economy in which the growth and inflation processes are calibrated to fit US data. Two related findings emerge: first, the proportion of bonds in the portfolios of even the most risk-averse agents is small (less than 2%); second, since equity dominates the portfolios of agents, the welfare loss due to variable inflation is small.
Characterization of T-bet and eomes in peripheral human immune cells.
The T-box transcription factors T-bet and Eomesodermin (Eomes) have been well defined as key drivers of immune cell development and cytolytic function. While the majority of studies have defined the roles of these factors in the context of murine T-cells, recent results have revealed that T-bet, and possibly Eomes, are expressed in other immune cell subsets. To date, the expression patterns of these factors in subsets of human peripheral blood mononuclear cells beyond T-cells remain relatively uncharacterized. In this study, we used multiparametric flow cytometry to characterize T-bet and Eomes expression in major human blood cell subsets, including total CD4(+) and CD8(+) T-cells, γδ T-cells, invariant NKT cells, natural killer cells, B-cells, and dendritic cells. Our studies identified novel cell subsets that express T-bet and Eomes and raise implications for their possible functions in the context of other human immune cell subsets besides their well-known roles in T-cells.
The corrigendum regards data and text for the final figure of the manuscript, Figure 7: Subsequent analysis of T-bet levels in human lymphocytes comparing different permeabilization procedures (eBioscience FoxP3 transcription factor kit, BD Pharmingen Cytofix/Cytoperm) has revealed variable findings in the level of T-bet expression detected within certain lymphocyte populations. While this does not change our conclusions for the majority of the populations assessed in this study, B cells in particular show differences under these conditions. Specifically, permeabilization via the eBioscience FoxP3 transcription factor staining buffer set indicates that subpopulations of memory B cells express significantly higher levels of T-bet (MFI) compared to plasmablasts, and that plasmablasts express T-bet only at low levels. Subsequent RNA transcript analysis confirms that plasmablasts express T-bet RNA at a level comparable to naïve B cells. Together, in combination with fluorescence-minus-one and isotype control studies, these new findings suggest that subsets memory B cells, not plasmablasts, express the highest levels of T-bet in the B cell compartment and plasmablasts express T-bet at a lower frequency than is reported in Figure 7. Figure 7 Legend should read: (C) Histograms depicting T-bet expression levels in B-cells and NK cells from a representative donor. Histograms represent the following subsets: naïve B-cells (thick black line), memory B-cells (shaded gray), plasmablasts (thin black line), CD56bright NK cells (gray line), and CD56dim NK cells (shaded black). B-cell results section should be titled T-bet is predominantly expressed in mature memory B-cells and should read: While Eomes was undetectable in B-cells (data not shown), we found T-bet in ~10% of B-cells (Figure 7B). This T-bet expression was largely relegated to memory B-cells, with significantly lower amounts observed in transitional/immature B-cells, naïve B-cells, and plasmablasts (Figure 7B). Greater than 15% of memory B-cells expressed T-bet, a significantly higher frequency than that of all other B-cell populations, suggesting that T-bet may play a particularly important role in memory B-cell function. The discussion related to T-bet expression in plasmablasts should be reconsidered as follows: We found that T-bet is not significantly expressed in transitional/immature B-cells, naïve B-cells, and plasmablasts, but is highly expressed in subsets of memory-B cells. Reduced frequencies of T-bet expression in plasmablasts indicate a specific role for T-bet at the memory B-cell stage of development, which may no longer be necessary after further differentiation to the plasmablast stage. Conflict of Interest Statement The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest
Immediate Cytotoxicity But Not Degranulation Distinguishes Effector and Memory Subsets of CD8+ T Cells
CD8+ T cells play a central role in the resolution and containment of viral infections. A key effector function of CD8+ T cells is their cytolytic activity toward infected cells. Here, we studied the regulation of cytolytic activity in naive, effector, and central versus effector memory CD8+ T cells specific for the same glycoprotein-derived epitope of lymphocytic choriomeningitis virus. Our results show that the kinetics of degranulation, assessed by a novel flow cytometric based assay, were identical in effector and both subsets of memory CD8+ T cells, but absent in naive CD8+ T cells. However, immediate cytolytic activity was most pronounced in effector T cells, low in effector memory T cells, and absent in central memory T cells, correlating with the respective levels of cytolytic effector molecules present in lytic granules. These results indicate that an inherent program of degranulation is a feature of antigen-experienced cells as opposed to naive CD8+ T cells and that the ability of CD8+ T cells to induce target cell apoptosis/death is dependent on granule protein content rather than on the act of degranulation itself. Furthermore, these results provide a potential mechanism by which central memory CD8+ T cell–mediated death of antigen-presenting cells within the lymph node is avoided
Global Substrate Mapping and Targeted Ablation with Novel Gold-tip Catheter in De Novo Persistent AF
Results from catheter ablation for persistent AF are suboptimal, with no strategy other than pulmonary vein isolation showing clear benefit. Recently employed empirical strategies beyond pulmonary vein isolation involve widespread atrial ablation in all patients and do not take into account patient-specific differences in AF mechanisms or phenotype. Charge density mapping using the non-contact AcQMap system (Acutus Medical) allows visualisation of whole-chamber activation during AF and reveals localised patterns of complex activation thought to represent important mechanisms for AF maintenance that can be targeted with focal ablation. In this review, the authors outline the fundamentals of this technology, the initial data exploring the mechanistic role of activation patterns seen and the application to ablation of persistent AF
Perturbed CD8+ T cell TIGIT/CD226/PVR axis despite early initiation of antiretroviral treatment in HIV infected individuals.
HIV-specific CD8+ T cells demonstrate an exhausted phenotype associated with increased expression of inhibitory receptors, decreased functional capacity, and a skewed transcriptional profile, which are only partially restored by antiretroviral treatment (ART). Expression levels of the inhibitory receptor, T cell immunoglobulin and ITIM domain (TIGIT), the co-stimulatory receptor CD226 and their ligand PVR are altered in viral infections and cancer. However, the extent to which the TIGIT/CD226/PVR-axis is affected by HIV-infection has not been characterized. Here, we report that TIGIT expression increased over time despite early initiation of ART. HIV-specific CD8+ T cells were almost exclusively TIGIT+, had an inverse expression of the transcription factors T-bet and Eomes and co-expressed PD-1, CD160 and 2B4. HIV-specific TIGIThi cells were negatively correlated with polyfunctionality and displayed a diminished expression of CD226. Furthermore, expression of PVR was increased on CD4+ T cells, especially T follicular helper (Tfh) cells, in HIV-infected lymph nodes. These results depict a skewing of the TIGIT/CD226 axis from CD226 co-stimulation towards TIGIT-mediated inhibition of CD8+ T cells, despite early ART. These findings highlight the importance of the TIGIT/CD226/PVR axis as an immune checkpoint barrier that could hinder future "cure" strategies requiring potent HIV-specific CD8+ T cells
What determines the optimal pharmacological treatment of atrial fibrillation? Insights from in silico trials in 800 virtual atria
The best pharmacological treatment for each atrial fibrillation (AF) patient is unclear. We aim to exploit AF simulations in 800 virtual atria to identify key patient characteristics that guide the optimal selection of anti-arrhythmic drugs. The virtual cohort considered variability in electrophysiology and low voltage areas (LVA) and was developed and validated against experimental and clinical data from ionic currents to ECG. AF sustained in 494 (62%) atria, with large inward rectifier K+ current (IK1) and Na+/K+ pump (INaK) densities (IK1 0.11 ± 0.03 vs. 0.07 ± 0.03 S mF–1; INaK 0.68 ± 0.15 vs. 0.38 ± 26 S mF–1; sustained vs. un-sustained AF). In severely remodelled left atrium, with LVA extensions of more than 40% in the posterior wall, higher IK1 (median density 0.12 ± 0.02 S mF–1) was required for AF maintenance, and rotors localized in healthy right atrium. For lower LVA extensions, rotors could also anchor to LVA, in atria presenting short refractoriness (median L-type Ca2+ current, ICaL, density 0.08 ± 0.03 S mF–1). This atrial refractoriness, modulated by ICaL and fast Na+ current (INa), determined pharmacological treatment success for both small and large LVA. Vernakalant was effective in atria presenting long refractoriness (median ICaL density 0.13 ± 0.05 S mF–1). For short refractoriness, atria with high INa (median density 8.92 ± 2.59 S mF–1) responded more favourably to amiodarone than flecainide, and the opposite was found in atria with low INa (median density 5.33 ± 1.41 S mF–1). In silico drug trials in 800 human atria identify inward currents as critical for optimal stratification of AF patient to pharmacological treatment and, together with the left atrial LVA extension, for accurately phenotyping AF dynamics
Chinese Economic Growth: Sources and Prospects
China's impressive growth is rooted in the liberalization of a surplus labor economy that has a high saving rate. The reallocation of surplus agriculture labor to industry and service sectors generates a growth effect that shows up in total factor productivity (TFP) growth. Net TFP, the resulting residual, contains the true measure of technological progress (among other effects). Taking account of mismeasurement problems, especially of value added in the industry sector, I calculated a plausible range of estimates for each source of growth. My point estimates for each of their contribution to the average annual 9.3 percent growth rate in the 1979-93 period growth rate in the 1985-93 subperiod are, respectively: 1979-93 1985-93 4.9 5.5 percentage points from capital accumulation 1.3 1.1 percentage points from labor force expansion. 1.1 1.3 percentage points from reallocation of labor from agriculture 0.2 0.3 percentage points from inconsistent use of base prices, 0.5Ã?0.7 0.9Ã?1.2 percentage points from overstatement of industrial growth, 1.1-1.3 0.3Ã?0.6 percentage points from net TFP growth.
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