Applications of Secure Multiparty Computation

We generate and gather a lot of data about ourselves and others, some of it highly confidential. The collection, storage and use of this data is strictly regulated by laws, but restricting the use of data often limits the benefits which could be obtained from its analysis. Secure multi-party computation (SMC), a cryptographic technology, makes it possible to execute specific programs on confidential data while ensuring that no other sensitive information from the data is leaked. SMC has been the subject of academic study for more than 30 years, but first attempts to use it for actual computations in the early 2000s – although theoretically efficient – were initially not practicable. However, improvements in the situation have made possible the secure solving of even relatively large computational tasks. This book describes how many different computational tasks can be solved securely, yet efficiently. It describes how protocols can be combined to larger applications, and how the security-efficiency trade-offs of different components of an SMC application should be chosen. Many of the results described in this book were achieved as part of the project Usable and Efficient Secure Multi-party Computation (UaESMC), which was funded by the European Commission. The book will be of interest to all those whose work involves the secure analysis of confidential data

Digital Deblurring of CMB Maps II: Asymmetric Point Spread Function

In this second paper in a series dedicated to developing efficient numerical techniques for the deblurring Cosmic Microwave Background (CMB) maps, we consider the case of asymmetric point spread functions (PSF). Although conceptually this problem is not different from the symmetric case, there are important differences from the computational point of view because it is no longer possible to use some of the efficient numerical techniques that work with symmetric PSFs. We present procedures that permit the use of efficient techniques even when this condition is not met. In particular, two methods are considered: a procedure based on a Kronecker approximation technique that can be implemented with the numerical methods used with symmetric PSFs but that has the limitation of requiring only mildly asymmetric PSFs. The second is a variant of the classic Tikhonov technique that works even with very asymmetric PSFs but that requires discarding the edges of the maps. We provide details for efficient implementations of the algorithms. Their performance is tested on simulated CMB maps.Comment: 9 pages, 13 Figure

Effect of Surface Patterning and Presence of Collagen I on the Phenotypic Changes of Embryonic Stem Cell Derived Cardiomyocytes

Embryonic stem cell derived cardiomyocytes have been widely investigated for stem cell therapy or in vitro model systems. This study examines how two specific biophysical stimuli, collagen I and cell alignment, affect the phenotypes of embryonic stem cell derived cardiomyocytes in vitro. Three phenotypic indicators are assessed: sarcomere organization, cell elongation, and percentage of binucleation. Murine embryonic stem cells were differentiated in a hanging drop assay and cardiomyocytes expressing GFP-α-actinin were isolated by fluorescent sorting. First, the effect of collagen I was investigated. Addition of soluble collagen I markedly reduced binucleation as a result of an increase in cytokinesis. Laden with a collagen gel layer, myocyte mobility and cell shape change were impeded. Second, the effect of cell alignment by microcontact printing and nanopattern topography was investigated. Both patterning techniques induced cell alignment and elongation. Microcontact printing of 20 μm line pattern accelerated binucleation and nanotopography with 700 nm ridges and 3.5 μm grooves negatively regulated binucleation. This study highlights the importance of biophysical cues in the morphological changes of differentiated cardiomyocytes and may have important implications on how these cells incorporate into the native myocardium.Singapore-MIT Alliance for Research and TechnologyNational Science Foundation (U.S.) ((Science and Technology Center (EBICS): Emergent Behaviors of Integrated Cellular Systems, Grant CBET-0939511)Charles Stark Draper Laboratory (Internal Research and Development Program

In Vitro Model of Tumor Cell Extravasation

Tumor cells that disseminate from the primary tumor and survive the vascular system can eventually extravasate across the endothelium to metastasize at a secondary site. In this study, we developed a microfluidic system to mimic tumor cell extravasation where cancer cells can transmigrate across an endothelial monolayer into a hydrogel that models the extracellular space. The experimental protocol is optimized to ensure the formation of an intact endothelium prior to the introduction of tumor cells and also to observe tumor cell extravasation by having a suitable tumor seeding density. Extravasation is observed for 38.8% of the tumor cells in contact with the endothelium within 1 day after their introduction. Permeability of the EC monolayer as measured by the diffusion of fluorescently-labeled dextran across the monolayer increased 3.8 fold 24 hours after introducing tumor cells, suggesting that the presence of tumor cells increases endothelial permeability. The percent of tumor cells extravasated remained nearly constant from1 to 3 days after tumor seeding, indicating extravasation in our system generally occurs within the first 24 hours of tumor cell contact with the endothelium

Sequence-independent activation of photocycloadditions using two colours of light

We exploit two reactive chromophores to establish sequence-independent photochemical activation, employing ortho-methyl benzaldehyde (oMBA) and N,N-(dimethylamino)pyrene aryl tetrazole (APAT) with N-(2-hydroxy)ethyl maleimide (NHEM), without any additives. Critically, the order of the irradiation sequence is irrelevant, as the shorter wavelength does not activate the higher wavelength activated species. Therefore, full sequence-independent λ-orthogonality is achieved through differences in both the reaction quantum yields (Φr,oMBA and Φr,APAT) and wavelength-dependent reactivity profiles of the employed chromophore

Knowledge of Objective 'Oughts': Monotonicity and the New Miners Puzzle

In the classic Miners case, an agent subjectively ought to do what they know is objectively wrong. This case shows that the subjective and objective ‘oughts’ are somewhat independent. But there remains a powerful intuition that the guidance of objective ‘oughts’ is more authoritative—so long as we know what they tell us. We argue that this intuition must be given up in light of a monotonicity principle, which undercuts the rationale for saying that objective ‘oughts’ are an authoritative guide for agents and advisors

High Cell Diversity and Complex Peptidergic Signaling Underlie Placozoan Behavior.

Placozoans, together with sponges, are the only animals devoid of a nervous system and muscles, yet both respond to sensory stimulation in a coordinated manner. How behavioral control in these free-living animals is achieved in the absence of neurons and, more fundamentally, how the first neurons evolved from more primitive cells for communication during the rise of animals are not yet understood [1-5]. The placozoan Trichoplax adhaerens is a millimeter-wide, flat, free-living marine animal composed of six morphologically identified cell types distributed across a simple body plan [6-9]: a thin upper epithelium and a columnar lower epithelium interspersed with a loose layer of fiber cells in between. Its genome contains genes encoding several neuropeptide-precursor-like proteins and orthologs of proteins involved in neurosecretion in animals with a nervous system [10-12]. Here we investigate peptidergic signaling in T. adhaerens. We found specific expression of several neuropeptide-like molecules in non-overlapping cell populations distributed over the three cell layers, revealing an unsuspected cell-type diversity of T. adhaerens. Using live imaging, we discovered that treatments with 11 different peptides elicited striking and consistent effects on the animals' shape, patterns of movement, and velocity that we categorized under three main types: (1) crinkling, (2) turning, and (3) flattening and churning. Together, the data demonstrate a crucial role for peptidergic signaling in nerveless placozoans and suggest that peptidergic volume signaling may have pre-dated synaptic signaling in the evolution of nervous systems

Human 3D vascularized organotypic microfluidic assays to study breast cancer cell extravasation

A key aspect of cancer metastases is the tendency for specific cancer cells to home to defined subsets of secondary organs. Despite these known tendencies, the underlying mechanisms remain poorly understood. Here we develop a microfluidic 3D in vitro model to analyze organ-specific human breast cancer cell extravasation into bone- and muscle-mimicking microenvironments through a microvascular network concentrically wrapped with mural cells. Extravasation rates and microvasculature permeabilities were significantly different in the bone-mimicking microenvironment compared with unconditioned or myoblast containing matrices. Blocking breast cancer cell A[subscript 3] adenosine receptors resulted in higher extravasation rates of cancer cells into the myoblast-containing matrices compared with untreated cells, suggesting a role for adenosine in reducing extravasation. These results demonstrate the efficacy of our model as a drug screening platform and a promising tool to investigate specific molecular pathways involved in cancer biology, with potential applications to personalized medicine.National Cancer Institute (U.S.) (Grant R33 CA174550-01)National Cancer Institute (U.S.) (Grant R21 CA140096)Italian Ministry of HealthCharles Stark Draper Laboratory (Fellowship

Post-Collision Interaction with Wannier electrons

A theory of the Post-Collision Interaction (PCI) is developed for the case when an electron atom impact results in creation of two low-energy Wannier electrons and an ion excited into an autoionizing state. The following autoionization decay exposes the Wannier pair to the influence of PCI resulting in variation of the shape of the line in the autoionization spectrum. An explicit dependence of the autoionization profile on the wave function of the Wannier pair is found. PCI provides an opportunity to study this wave function for a wide area of distancesComment: 33 pages, Latex, IOP style, and 3 figures fig1.ps, fig2.ps, fig3.p