Political connection heterogeneity and firm value in Vietnam

The observation of firms’ political connections (PCs) in both types of ascribed and acquired PCs has raised the question of their benefits to firms’ operation. Based on 1,365 Vietnamese listed firm-year observations from 2010 to 2014, we find that although firms with both ascribed and acquired PCs have lower firm value (FV) than firms without any PCs, firms with acquired PCs exhibit better FV than those with ascribed PCs. The paper also reveals that concentrated ownership (CO) has a mediation impact on the association between acquired PCs and FV while it can help firms with acquired PCs in improving FV

Sequence Space Localization in the Immune System Response to Vaccination and Disease

We introduce a model of protein evolution to explain limitations in the immune system response to vaccination and disease. The phenomenon of original antigenic sin, wherein vaccination creates memory sequences that can \emph{increase} susceptibility to future exposures to the same disease, is explained as stemming from localization of the immune system response in antibody sequence space. This localization is a result of the roughness in sequence space of the evolved antibody affinity constant for antigen and is observed for diseases with high year-to-year mutation rates, such as influenza.Comment: 5 pages, 2 figure

CNN-Based Projected Gradient Descent for Consistent Image Reconstruction

We present a new method for image reconstruction which replaces the projector in a projected gradient descent (PGD) with a convolutional neural network (CNN). CNNs trained as high-dimensional (image-to-image) regressors have recently been used to efficiently solve inverse problems in imaging. However, these approaches lack a feedback mechanism to enforce that the reconstructed image is consistent with the measurements. This is crucial for inverse problems, and more so in biomedical imaging, where the reconstructions are used for diagnosis. In our scheme, the gradient descent enforces measurement consistency, while the CNN recursively projects the solution closer to the space of desired reconstruction images. We provide a formal framework to ensure that the classical PGD converges to a local minimizer of a non-convex constrained least-squares problem. When the projector is replaced with a CNN, we propose a relaxed PGD, which always converges. Finally, we propose a simple scheme to train a CNN to act like a projector. Our experiments on sparse view Computed Tomography (CT) reconstruction for both noiseless and noisy measurements show an improvement over the total-variation (TV) method and a recent CNN-based technique

Influence of socioeconomic inertia and uncertainty on optimal CO2-emission abatement

Following the UN Framework Convention on Climate Change [1], countries will negotiate in Kyoto this December an agreement to mitigate greenhouse gas emissions. Here we examine optimal CO2 policies, given long-term constraints on atmospheric concentrations. Our analysis highlights the interplay of uncertainty and socioeconomic inertia. We find that the ‘integrated assessment' models so far applied under-represent inertia, and we show that higher adjustment costs make it optimal to spread the effort across generations and increase the costs of deferring abatement. Balancing the costs of early action against the potentially higher costs of a more rapid forced subsequent transition, we show that early attention to the carbon content of new and replacement investments reduces the exposure of both the environmental and the economic systems to the risks of costly and unpleasant surprises. If there is a significant probability of having to stay below a doubling of atmospheric CO2-equivalent, deferring abatement may prove costly.

The economics of changing course: implications of adaptability and inertia for optimal climate policy.

http://www.centre-cired.fr/perso/haduong/files/Grubb.ea-1995-EconomicsOfChangingCourses.pdfInternational audienceThis paper reviews evidence that energy technologies and systems adapt over time to accomodate external pressures: that technical innovation and systemic change in the energy sector is largely induced by need, and restrained by potentially large transitional costs. A simple integrated model of optimal greenhouse gas abatement over time is presented, in which the abatement cost depends on both fixed and transitional elements. It is shown that the optimal current response and long-run prospects differ radically between the classical economic case - in which the cost of a given cutback in emissions is fixed exogenously - and the adaptative case - in which the response is ultimately adaptative but heavily constrained by inertia (i.e. low fixed but high transitional costs). If energy systems are indeed to a large degree adaptive, the results demonstrate that as compared with the classical non-adaptive case: long-run stabilization of atmospheric CO2 may be optimal even with moderate damages from climate change; greater near-term abatement efforts are justified; and the cost of a given delay in response may be several times higher. Neglect of the issue of induced technical change and other adaptive responses may invalidate the policy implications drawn from most integrated assessment models developed to date