title: Coulomb-oscillator duality in spaces of constant curvature

authors: Kalnins, Ernie G.

subjects: Mathematics

abstract: In this paper we construct generalizations to spheres of the well-known Levi-Civita, Kustaanheimo–Steifel, and Hurwitz regularizing transformations in Euclidean spaces of dimensions two, three, and five. The corresponding classical and quantum mechanical analogs of the Kepler–Coulomb problem on these spheres are discussed.

text: Coulomb-oscillator duality in spaces of constant curvature In this paper we construct generalizations to spheres of the well-known Levi-Civita, Kustaanheimo–Steifel, and Hurwitz regularizing transformations in Euclidean spaces of dimensions two, three, and five. The corresponding classical and quantum mechanical analogs of the Kepler–Coulomb problem on these spheres are discussed.

year: 2000-05

title: Nanosecond protein dynamics:  First detection of a neutron incoherent spin−echo signal

authors: Bellissent-Funel, Marie-Claire

subjects: biology

abstract: Motions in proteins occur over a wide range of time scales, from femtoseconds to seconds or longer.¹⁻³ Therefore, their characterization requires the application of a correspondingly wide range of experimental probes. Among these incoherent neutron scattering (INS) is a particularly direct source of information on time scales and forms of hydrogen motions.⁴⁻⁸ However, due to limited accuracy in the measurement of energy changes of scattered neutrons, INS work has been limited to the 10⁻¹⁵-10⁻¹⁰s time scales. The neutron spin-echo technique was developed to overcome this limitation.⁹ Neutron spin-echo allows precise measurement of velocity changes of neutrons via Larmor precession of the neutron’s spin. This has led to the possibility of extracting information on atomic motions on nanosecond and longer time scales.

text: Nanosecond protein dynamics:  First detection of a neutron incoherent spin−echo signal Motions in proteins occur over a wide range of time scales, from femtoseconds to seconds or longer.¹⁻³ Therefore, their characterization requires the application of a correspondingly wide range of experimental probes. Among these incoherent neutron scattering (INS) is a particularly direct source of information on time scales and forms of hydrogen motions.⁴⁻⁸ However, due to limited accuracy in the measurement of energy changes of scattered neutrons, INS work has been limited to the 10⁻¹⁵-10⁻¹⁰s time scales. The neutron spin-echo technique was developed to overcome this limitation.⁹ Neutron spin-echo allows precise measurement of velocity changes of neutrons via Larmor precession of the neutron’s spin. This has led to the possibility of extracting information on atomic motions on nanosecond and longer time scales.

year: 1998

title: A core phyllosphere microbiome exists across distant populations of a tree species indigenous to New Zealand

authors: Noble, Anya S.

subjects: Science & Technology

abstract: The phyllosphere microbiome is increasingly recognised as an influential component of plant physiology, yet it remains unclear whether stable host-microbe associations generally exist in the phyllosphere. Leptospermum scoparium (mānuka) is a tea tree indigenous to New Zealand, and honey derived from mānuka is widely known to possess unique antimicrobial properties. However, the host physiological traits associated with these antimicrobial properties vary widely, and the specific cause of such variation has eluded scientists despite decades of research. Notably, the mānuka phyllosphere microbiome remains uncharacterised, and its potential role in mediating host physiology has not been considered. Working within the prevailing core microbiome conceptual framework, we hypothesise that the phyllosphere microbiome of mānuka exhibits specific host association patterns congruent with those of a microbial community under host selective pressure (null hypothesis: the mānuka phyllosphere microbiome is recruited stochastically from the surrounding environment). To examine our hypothesis, we characterised the phyllosphere and associated soil microbiomes of five distinct and geographically distant mānuka populations across the North Island of New Zealand. We identified a habitat-specific and relatively abundant core microbiome in the mānuka phyllosphere, which was persistent across all samples. In contrast, non-core phyllosphere microorganisms exhibited significant variation across individual host trees and populations that was strongly driven by environmental and spatial factors. Our results demonstrate the existence of a dominant and ubiquitous core microbiome in the phyllosphere of mānuka, supporting our hypothesis that phyllosphere microorganisms of mānuka exhibit specific host association and potentially mediate physiological traits of this nationally and culturally treasured indigenous plant. In addition, our results illustrate biogeographical patterns in mānuka phyllosphere microbiomes and offer insight into factors contributing to phyllosphere microbiome assembly.

text: A core phyllosphere microbiome exists across distant populations of a tree species indigenous to New Zealand The phyllosphere microbiome is increasingly recognised as an influential component of plant physiology, yet it remains unclear whether stable host-microbe associations generally exist in the phyllosphere. Leptospermum scoparium (mānuka) is a tea tree indigenous to New Zealand, and honey derived from mānuka is widely known to possess unique antimicrobial properties. However, the host physiological traits associated with these antimicrobial properties vary widely, and the specific cause of such variation has eluded scientists despite decades of research. Notably, the mānuka phyllosphere microbiome remains uncharacterised, and its potential role in mediating host physiology has not been considered. Working within the prevailing core microbiome conceptual framework, we hypothesise that the phyllosphere microbiome of mānuka exhibits specific host association patterns congruent with those of a microbial community under host selective pressure (null hypothesis: the mānuka phyllosphere microbiome is recruited stochastically from the surrounding environment). To examine our hypothesis, we characterised the phyllosphere and associated soil microbiomes of five distinct and geographically distant mānuka populations across the North Island of New Zealand. We identified a habitat-specific and relatively abundant core microbiome in the mānuka phyllosphere, which was persistent across all samples. In contrast, non-core phyllosphere microorganisms exhibited significant variation across individual host trees and populations that was strongly driven by environmental and spatial factors. Our results demonstrate the existence of a dominant and ubiquitous core microbiome in the phyllosphere of mānuka, supporting our hypothesis that phyllosphere microorganisms of mānuka exhibit specific host association and potentially mediate physiological traits of this nationally and culturally treasured indigenous plant. In addition, our results illustrate biogeographical patterns in mānuka phyllosphere microbiomes and offer insight into factors contributing to phyllosphere microbiome assembly.

year: 2020