Picking a CHERI Allocator: Security and Performance Considerations

Several open-source memory allocators have been ported to CHERI, a hardware capability platform. In this paper we examine the security and performance of these allocators when run under CheriBSD on Arm's experimental Morello platform. We introduce a number of security attacks and show that all but one allocator are vulnerable to some of the attacks - including the default CheriBSD allocator. We then show that while some forms of allocator performance are meaningful, comparing the performance of hybrid and pure capability (i.e. 'running in non-CHERI vs. running in CHERI modes') allocators does not appear to be meaningful. Although we do not fully understand the reasons for this, it seems to be at least as much due to factors such as immature compiler toolchains as it is due to the effects of capabilities on hardware

Colorimetric Identification of Proteins Using Gold Nanoparticles

Proteins are the principal executive biomolecules of life. Their existence is required to drive and regulate countless physiological and biochemical activities within the cell. The study of biochemistry and biology are therefore frequently concerned with monitoring the presence, distribution, and function of proteins. Conventional protein identification assays are often labour-intensive and rely on the use of expensive antibodies. The development of new protein biosensors that incorporate nanotechnology, specifically gold nanoparticles (AuNPs), may allow for facile detection, identification, and quantification of proteins due to their colorimetric output. Unlike other strategies that use antibody-functionalized gold nanoparticles, the pairing of non-functionalized nanoparticles with spectroscopic analysis may further reduce the cost of analysis and make this technology viable for consumer-level applications. This thesis focuses on the development of a gold nanoparticle biosensor for the detection, identification, and quantification of proteins. The underlying principle is based on the aggregation of non-functionalized gold nanoparticles in the presence of proteins. The physicochemical characteristics of these gold nanoparticles can be manipulated to alter their response to different proteins. In order to achieve identification based on non-specific interactions, a “chemical nose” strategy is followed, whereby different gold-nanoparticles produce different individual responses, and their collective response defines a unique signature for a given protein. A review of current literature presents the variety of biological, chemical, and physical factors that can affect protein-nanoparticle interactions, and their resultant effect on colloidal stability. This review also highlights the complexity with which these factors can interact and identifies key considerations for maintaining or controlling colloidal stability in various applications. The experiments herein address the role of shape and surfactant-type on aggregation of gold nanoparticles. Shape has previously been shown to affect protein-nanoparticle interactions, but to our knowledge has not been exploited for protein sensing applications. The role of surfactant on protein-gold nanoparticle interactions is not well studied and provides a novel avenue for investigation. This work demonstrates that both these parameters can be used to alter protein-nanoparticle interactions, thereby permitting “chemical nose”-type detection of proteins. Overall, these studies highlight how modifying protein-nanoparticle interactions can be used for the benefit of biosensing in research and clinical settings. In addition to biosensing, this manner of investigation can serve as a powerful tool to study protein-nanoparticle interactions, with widespread implications in medicine, environmental protection, and water treatment

L'outil d'aide à la décision GeDSeT : évaluer les impacts et bénéfices de différentes options de gestion des sédiments

National audienceThe GeDSeT decision support tool: evaluating impacts and benefits of different options for sediment managemen

Albert Laurence Prosser Correspondence

Entries include handwritten biographical letters on Monhegan Art School and Ye Picket Fence stationery, a lengthy typed book release with history of Monhegan, Maine, a handwritten plain postcard and letters with reference to book publishing and research, typed letters on homemade and printed personal stationery concerning the early working title for Our Elusive Willy, and a printed publisher advertisement with artwork for the book and a biography

The GeDSeT project: (constitution of a decision support tool (DST) for the management and material recovery of waterways sediments in Belgium and Northern France)

International audienceThe European InterReg IV GeDSeT project (2008-2013) is a contribution to a sustainable management of waterways sediments, in order to develop good practice for the development of regional fluvial transport, water resource protection and land resources preservation. The GeDSeT decision support tool (DST), one of the results of this project, carried out as a partnership between Ecole des Mines de Douai, ISSeP, CTP, INERIS and BRGM, members of the GIS-3SP cluster, aims to provide sediment management options with relevant quantitative data, in order to evaluate various scenarios taking into account cost and sustainability

Ethan Allen Chase Correspondence

Entries include letters of correspondence from the Maine State Library to Allen\u27s granddaughter and a handwritten letter of presentation from Achilles

Atomic Force Microscopy-Based Screening of Drug-Excipient Miscibility and Stability of Solid Dispersions

ABSTRACT: Purpose: Development of a method to assess the drug/polymer miscibility and stability of solid dispersions using a melt-based mixing method. Methods: Amorphous fractured films are prepared and characterized with Raman Microscopy in combination with Atomic Force Microscopy to discriminate between homogenously and heterogeneously mixed drug/polymer combinations. The homogenous combinations are analyzed further for physical stability under stress conditions, such as increased humidity or temperature. Results: Combinations that have the potential to form a molecular disperse mixture are identified. Their potential to phase separate is determined through imaging at molecular length scales, which results in short observation time. De-mixing is quantified by phase separation analysis, and the drug/polymer combinations are ranked to identify the most stable combinations. Conclusions: The presented results demonstrate that drug/polymer miscibility and stability of solid dispersions, with many mechanistic details, can be analyzed with Atomic Force Microscopy. The assay allows to identify well-miscible and stable combinations within hours or a few day

Simulating permeability reduction by clay mineral nanopores in a tight sandstone by combining computer X-ray microtomography and focussed ion beam scanning electron microscopy imaging

Computer X-ray microtomography (µXCT) represents a powerful tool for investigating the physical properties of porous rocks. While calculated porosities determined by this method typically match experimental measurements, computed permeabilities are often overestimated by more than 1 order of magnitude. This effect increases towards smaller pore sizes, as shown in this study, in which nanostructural features related to clay minerals reduce the permeability of tight reservoir sandstone samples. Focussed ion beam scanning electron microscopy (FIB-SEM) tomography was applied to determine the permeability effects of illites at the nanometre scale, and Navier–Stokes equations were applied to calculate the permeability of these domains. With these data, microporous domains (porous voxels) were defined using microtomography images of a tight reservoir sample. The distribution of these domains could be extrapolated by calibration against size distributions measured in FIB-SEM images. For this, we assumed a mean permeability for the dominant clay mineral (illite) in the rock and assigned it to the microporous domains within the structure. The results prove the applicability of our novel approach by combining FIB-SEM with X-ray tomographic rock core scans to achieve a good correspondence between measured and simulated permeabilities. This methodology results in a more accurate representation of reservoir rock permeability in comparison to that estimated purely based on µXCT images