University of Massachusetts Amherst

About: University of Massachusetts Amherst is a education organization based out in Amherst Center, Massachusetts, United States. It is known for research contribution in the topics: Population & Galaxy. The organization has 37274 authors who have published 83965 publications receiving 3834996 citations. The organization is also known as: UMass Amherst & Massachusetts State College.

Protein-stabilized emulsions

Abstract: Proteins are widely used as emulsifiers to facilitate the formation, improve the stability and provide specific physicochemical properties to oil-in-water emulsions. There have been a number of recent advances in the understanding of the ability of various types of proteins to provide these functional properties. This article focuses on the influence of solution composition (pH, ionic strength, sugars, polyols, surfactants, biopolymers) and environmental stresses (heating, chilling, freezing, drying) on the stability of globular protein stabilized emulsions.

Power-Up SRAM State as an Identifying Fingerprint and Source of True Random Numbers

Abstract: Intermittently powered applications create a need for low-cost security and privacy in potentially hostile environments, supported by primitives including identification and random number generation. Our measurements show that power-up of SRAM produces a physical fingerprint. We propose a system of fingerprint extraction and random numbers in SRAM (FERNS) that harvests static identity and randomness from existing volatile CMOS memory without requiring any dedicated circuitry. The identity results from manufacture-time physically random device threshold voltage mismatch, and the random numbers result from runtime physically random noise. We use experimental data from high-performance SRAM chips and the embedded SRAM of the WISP UHF RFID tag to validate the principles behind FERNS. For the SRAM chip, we demonstrate that 8-byte fingerprints can uniquely identify circuits among a population of 5,120 instances and extrapolate that 24-byte fingerprints would uniquely identify all instances ever produced. Using a smaller population, we demonstrate similar identifying ability from the embedded SRAM. In addition to identification, we show that SRAM fingerprints capture noise, enabling true random number generation. We demonstrate that a 512-byte SRAM fingerprint contains sufficient entropy to generate 128-bit true random numbers and that the generated numbers pass the NIST tests for runs, approximate entropy, and block frequency.

Morphological Transformation from Galaxy Harassment

Abstract: Galaxy morphologies in clusters have undergone a remarkable transition over the past several billion yr. Distant clusters at z ~ 0.4 are filled with small spiral galaxies, many of which are disturbed and show evidence of multiple bursts of star formation. This population is absent from nearby clusters, where spheroidals comprise the faint end of the luminosity function. Our numerical simulations follow the evolution of disk galaxies in a rich cluster resulting from encounters with brighter galaxies and the cluster's tidal field, or galaxy harassment. After a bursting transient phase, they undergo a complete morphological transformation from disks to spheroidals. We examine the remnants and find support for our theory in detailed comparisons of the photometry and kinematics of the spheroidal galaxies in clusters. Our model naturally accounts for the intermediate-age stellar population seen in these spheroidals, as well as for the trend in the dwarf-to-giant ratio with cluster richness. The final shapes are typically prolate and are flattened primarily by velocity anisotropy. Their mass-to-light ratios are in the range 3-8, in good agreement with observations.

Invasiveness, invasibility and the role of environmental stress in the spread of non-native plants

Abstract: Invasion ecology, the study of how organisms spread in habitats to which they are not native, asks both about the invasiveness of species and the invasibility of habitats: Which species are most likely to become invasive? Which habitats are most susceptible to invasion? To set the stage for considering these questions with regard to plants, we offer a two-way classification of nativeness and invasiveness that distinguishes natives, non-invasive non-natives and invasive non-natives. We then consider the current state of knowledge about invasiveness and invasibility. Despite much investigation, it has proven difficult to identify traits that consistently predict invasiveness. This may be largely because different traits favour invasiveness in different habitats. It has proven easier to identify types of habitats that are relatively invasible, such as islands and riverbanks. Factors thought to render habitats invasible include low intensities of competition, altered disturbance regimes and low levels of environmental stress, especially high resource availability. These factors probably often interact; the combination of altered disturbance with high resource availability may particularly promote invasibility. When biotic factors control invasibility, non-natives that are unlike native species may prove more invasive; the converse may also be true. We end with a simple conceptual model for cases in which high levels of environmental stress should and should not reduce invasibility. In some cases, it may be possible to manipulate stress to control biological invasions by plants.