7,240 research outputs found
Development of methodologies and procedures for identifying STS users and uses
A study was conducted to identify new uses and users of the new Space Transporation System (STS) within the domestic government sector. The study develops a series of analytical techniques and well-defined functions structured as an integrated planning process to assure efficient and meaningful use of the STS. The purpose of the study is to provide NASA with the following functions: (1) to realize efficient and economic use of the STS and other NASA capabilities, (2) to identify new users and uses of the STS, (3) to contribute to organized planning activities for both current and future programs, and (4) to air in analyzing uses of NASA's overall capabilities
Geriatric screening in first opinion practice: results from 45 dogs
Objectives
To evaluate and report the results of screening geriatric dogs in a first opinion practice.
Methods
A prospective health screen of dogs over nine-years-old involving history taking, physical examination and urinalysis.
Results
At least one previously unrecognised problem was identified in 80% of 45 dogs and 353 findings (mean 7·8 per dog) were recorded. Owners often failed to recognise and report serious signs of age-related disease. However, they most often reported increased sleeping (31%), loss of hearing (29%) or sight (20%), stiffness or lameness (22%) and âslowing downâ (20%). Increased lens opacity (64%), increased thirst (58%), pain (24%), increased frequency of urination (24%), signs of osteoarthritis (24%) and dental disease (22%) were most frequently identified at the time of consultation. Potentially, life-threatening findings included respiratory distress, palpable abdominal masses and metastatic lung disease. Screening resulted in 29 further diagnostic procedures, including 10 dental procedures, seven medical treatments, two surgical procedures and euthanasia of two dogs.
Clinical Significance
Screening elderly dogs identified unrecognised and unreported health risk factors resulting in lifestyle modification and ongoing monitoring, as well as signs of age-related diseases resulting in diagnostic investigations, early diagnoses and surgical and medical interventions to improve quality of life
Morphogenetic Theory and the Constructivist Institutionalist Challenge
This article engages with two meta-theoretical approaches to social analysis, âmorphogenetic theoryâ and âconstructivist institutionalismâ, and specifically explores how the former fares under the critical scrutiny of the latter. The key proponent of constructivist institutionalism, Colin Hay, has offered two detailed critiques of morphogenesis that criticise its position on the foundational sociological issues of structure-agency and material-ideational. Although Hayâs critiques are largely rejected in an overall defence of the morphogenetic approach, the process of engagement is seen to be particularly useful for morphogenetic theory because it allows a number of important clarifications to be made and it also opens up space for theoretical development. In the course of this debate, accessible introductions are given to both theories, and the similarities and differences between them are outlined, providing clarity to both. Therefore, although this article ultimately operates as a defence of morphogenetic theory, especially in the form proposed by Margaret Archer and Douglas Porpora, it finds a great deal of fruitful discussion in the constructivist institutionalist challenge
Exchange interactions and magnetic phases of transition metal oxides: benchmarking advanced ab initio methods
The magnetic properties of the transition metal monoxides MnO and NiO are
investigated at equilibrium and under pressure via several advanced
first-principles methods coupled with Heisenberg Hamiltonian MonteCarlo. The
comparative first-principles analysis involves two promising beyond-local
density functionals approaches, namely the hybrid density functional theory and
the recently developed variational pseudo-self-interaction correction method,
implemented with both plane-wave and atomic-orbital basis sets. The advanced
functionals deliver a very satisfying rendition, curing the main drawbacks of
the local functionals and improving over many other previous theoretical
predictions. Furthermore, and most importantly, they convincingly demonstrate a
degree of internal consistency, despite differences emerging due to
methodological details (e.g. plane waves vs. atomic orbitals
Theory for the phase behaviour of a colloidal fluid with competing interactions
We study the phase behaviour of a fluid composed of particles which interact
via a pair potential that is repulsive for large inter-particle distances, is
attractive at intermediate distances and is strongly repulsive at short
distances (the particles have a hard core). As well as exhibiting gas-liquid
phase separation, this system also exhibits phase transitions from the uniform
fluid phases to modulated inhomogeneous fluid phases. Starting from a
microscopic density functional theory, we develop an order parameter theory for
the phase transition in order to examine in detail the phase behaviour. The
amplitude of the density modulations is the order parameter in our theory. The
theory predicts that the phase transition from the uniform to the modulated
fluid phase can be either first order or second order (continuous). The phase
diagram exhibits two tricritical points, joined to one another by the line of
second order transitions.Comment: 12 pages, 9 figures. Accepted for publication in J. Phys. Condens.
Matte
Exceptionally strong magnetism in 4d perovskites RTcO3 (R=Ca,Sr,Ba)
The evolution of the magnetic ordering temperature of the 4d3 perovskites
RTcO3 (R=Ca,Sr,Ba) and its relation with its electronic and structural
properties has been studied by means of hybrid density functional theory and
Monte Carlo simulations. When compared to the most widely studied 3d
perovskites the large spatial extent of the 4d shells and their relatively
strong hybridization with oxygen weaken the tendency to form Jahn-Teller like
orbital ordering. This strengthens the superexchange interaction. The resulting
insulating G-type antiferromagnetic ground state is characterized by large
superexchange coupling constants (26-35 meV) and Neel temperatures (750-1200
K). These monotonically increase as a function of the R ionic radius due to the
progressive enhancement of the volume and the associated decrease of the
cooperative rotation of the TcO6 octahedra.Comment: 4 pages, 3 figure
The oceanic cycles of the transition metals and their isotopes
The stable isotope systems of the transition metals potentially provide constraints on the current and past operation of the biological pump, and on the state of ocean redox in Earth history. Here we focus on two exemplar metals, nickel (Ni) and zinc (Zn). The oceanic dissolved pool of both elements is isotopically heavier than the known inputs, implying an output with light isotope compositions. The modern oceanic cycle of both these elements is dominated by biological uptake into photosynthesised organic matter and output to sediment. It is increasingly clear, however, that such uptake is associated with only very minor isotope fractionation. We suggest that the isotopic balance is instead closed by the sequestration of light isotopes to sulphide in anoxic and organic-rich sediments, so that it is ocean chemistry that controls these isotope systems, and suggesting a different but equally interesting array of questions in Earth history that can be addressed with these systems
Augmented collisional ionization via excited states in XUV cluster interactions
The impact of atomic excited states is investigated via a detailed model of
laser-cluster interactions, which is applied to rare gas clusters in intense
femtosecond pulses in the extreme ultraviolet (XUV). This demonstrates the
potential for a two-step ionization process in laser-cluster interactions, with
the resulting intermediate excited states allowing for the creation of high
charge states and the rapid dissemination of laser pulse energy. The
consequences of this excitation mechanism are demonstrated through simulations
of recent experiments in argon clusters interacting with XUV radiation, in
which this two-step process is shown to play a primary role; this is consistent
with our hypothesis that XUV-cluster interactions provide a unique window into
the role of excited atomic states due to the relative lack of photoionization
and laser field-driven phenomena. Our analysis suggests that atomic excited
states may play an important role in interactions of intense radiation with
materials in a variety of wavelength regimes, including potential implications
for proposed studies of single molecule imaging with intense X-rays.Comment: 4 pages, 2 figure
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