Advocacy spurs innovation: promoting synergy between physical and biomedical sciences

Despite dramatic advances in decoding the genes, proteins, and pathways that drive cancer, the disease has evaded the reductionist approaches to defeat it. Recent work has highlighted cancer’s heterogeneity, complexity, and ability to develop resistance as major barriers to progress. To better understand and control the processes that govern the initiation, behavior, and progression of cancer, the National Cancer Institute (NCI) created the Physical Sciences-Oncology Center (PS-OC) Network in 2009. As a hub for scientific innovation and as an example of the transdisciplinary research model, the twelve centers within the PS-OC strive for the systematic convergence of the physical sciences with cancer biology. Promoting collaboration between biologists, physicists, mathematicians, chemists, biomedical engineers, and oncologists, the program offers a compelling vision of how new frontiers in physical sciences and oncology will permit the emergence of new scientific principles and opportunities, and of how the benefits of the current convergence revolution would be enhanced by vigorous public/advocacy support

A-quasiconvexity : relaxation and homogenization

Integral representation of relaxed energies and of Γ-limits of functionals (u, v)↦→�Ω f(x, u(x), v(x))dx are obtained when sequences of fields v may develop oscillations and are constrained to satisfy a system of first order linear partial differential equations. This framework includes the treatement of divergence-free fields, Maxwell’s equations in micromagnetics, and curl-free fields. In the latter case classical relaxation theorems in W 1,p are recovered

Integrin-Specific Mechanoresponses to Compression and Extension Probed by Cylindrical Flat-Ended AFM Tips in Lung Cells

Cells from lung and other tissues are subjected to forces of opposing directions that are largely transmitted through integrin-mediated adhesions. How cells respond to force bidirectionality remains ill defined. To address this question, we nanofabricated flat-ended cylindrical Atomic Force Microscopy (AFM) tips with ∼1 µm2 cross-section area. Tips were uncoated or coated with either integrin-specific (RGD) or non-specific (RGE/BSA) molecules, brought into contact with lung epithelial cells or fibroblasts for 30 s to form focal adhesion precursors, and used to probe cell resistance to deformation in compression and extension. We found that cell resistance to compression was globally higher than to extension regardless of the tip coating. In contrast, both tip-cell adhesion strength and resistance to compression and extension were the highest when probed at integrin-specific adhesions. These integrin-specific mechanoresponses required an intact actin cytoskeleton, and were dependent on tyrosine phosphatases and Ca2+ signaling. Cell asymmetric mechanoresponse to compression and extension remained after 5 minutes of tip-cell adhesion, revealing that asymmetric resistance to force directionality is an intrinsic property of lung cells, as in most soft tissues. Our findings provide new insights on how lung cells probe the mechanochemical properties of the microenvironment, an important process for migration, repair and tissue homeostasis

Systemic importance of financial institutions: regulations, research, open issues, proposals

In the field of risk management, scholars began to bring together the quantitative methodologies with the banking management issues about 30 years ago, with a special focus on market, credit and operational risks. After the systemic effects of banks defaults during the recent financial crisis, and despite a huge amount of literature in the last years concerning the systemic risk, no standard methodologies have been set up to now. Even the new Basel 3 regulation has adopted a heuristic indicator-based approach, quite far from an effective quantitative tool. In this paper, we refer to the different pieces of the puzzle: definition of systemic risk, a set of coherent and useful measures, the computability of these measures, the data set structure. In this challenging field, we aim to build a comprehensive picture of the state of the art, to illustrate the open issues, and to outline some paths for a more successful future research. This work appropriately integrates other useful surveys and it is directed to both academic researchers and practitioners

Regularity results for equilibria in a variational model for fracture

Abstract: "In recent years models describing interactions between fracture and damage have been proposed in which the relaxed energy of the material is given by a functional involving bulk and interfacial terms, of the form [equation] where [omega] is an open, bounded subset of R[superscript N], q [> or =] 1, g [element of]L[superscript infinity]([omega];R[superscript N]), [lambda], ╬▓ > 0, the bulk energy density F is quasiconvex, K [contained as subclass within] R[superscript N] is closed, and the admissible deformation u : [omega] -> R[superscript N] is C┬╣ in [omega]\K. One of the main issues has to do with regularity properties of the 'crack site' K for a minimizing pair (K, u). In the scalar case, i.e. when u : [omega] -> R, similar models were adopted to image segmentation problems, and the regularity of the 'edge' set K has been successfully resolved for a quite broad class of convex functions F with growth p > 1 at infinity. In turn, this regularity entails the existence of classical solutions. The methods thus used cannot be carried out to the vectorial case, except for a very restrictive class of integrands. In this paper we deal with a vector-valued case on the plane, obtaining regularity for minimizers of G corresponding to polyconvex bulk energy densities of the form F([Xi] = 1/2[absolute value of Xi]┬▓ + h(det [Xi]), where the convex function h grows linearly at infinity.

Regularity of minimizers for a class of membrane energies

Mathematics Technical Repor