5,096 research outputs found
MAJOR IDEAS IN THE HISTORY OF AGRICULTURAL FINANCE AND FARM MANAGEMENT
This paper contains two articles that discuss major ideas from the history of agricultural finance and farm management. The agricultural finance article focuses on ideas that emerged prior to 1960. These ideas are classified into those emerging from action and scientific-framing eras. The second article characterizes the evolution of farm management and production economics from its beginnings in about 1900 to the start of the 21st century. Emphasis is placed on the melding of ideas from agriculturalists and economists.Agricultural finance, farm management, production economics, Agricultural Finance,
Mode coupling and multiquantum vibrational excitations in Feshbach-resonant positron annihilation in molecules
The dominant mechanism of low-energy positron annihilation in polyatomic
molecules is through positron capture in vibrational Feshbach resonances (VFR).
In this paper we investigate theoretically the effect of anharmonic terms in
the vibrational Hamiltonian on the positron annihilation rates. Such
interactions enable positron capture in VFRs associated with multiquantum
vibrational excitations, leading to enhanced annihilation. Mode coupling can
also lead to faster depopulation of VFRs, thereby reducing their contribution
to the annihlation rates. To analyze this complex picture, we use
coupled-cluster methods to calculate the anharmonic vibrational spectra and
dipole transition amplitudes for chloroform, chloroform-,
1,1-dichloroethylene, and methanol, and use these data to compute positron
resonant annihilation rates for these molecules. Theoretical predictions are
compared with the annihilation rates measured as a function of incident
positron energy. The results demonstrate the importance of mode coupling in
both enhancement and suppression of the VFR. There is also experimental
evidence for the direct excitation of multimode VFR. Their contribution is
analyzed using a statistical approach, with an outlook towards more accurate
treatment of this phenomenon.Comment: 16 pages, 10 figures, submitted to Phys. Rev.
Excited-state Forces within a First-principles Green's Function Formalism
We present a new first-principles formalism for calculating forces for
optically excited electronic states using the interacting Green's function
approach with the GW-Bethe Salpeter Equation method. This advance allows for
efficient computation of gradients of the excited-state Born-Oppenheimer
energy, allowing for the study of relaxation, molecular dynamics, and
photoluminescence of excited states. The approach is tested on photoexcited
carbon dioxide and ammonia molecules, and the calculations accurately describe
the excitation energies and photoinduced structural deformations.Comment: 2 figures and 2 table
Behavioural compensation by drivers of a simulator when using a vision enhancement system
Technological progress is suggesting dramatic changes to the tasks of the driver, with the general aim of making driving environment safer. Before any of these technologies are implemented, empirical research is required to establish if these devices do, in fact, bring about the anticipated improvements. Initially, at least, simulated driving environments offer a means of conducting this research. The study reported here concentrates on the application of a vision enhancement (VE) system within the risk homeostasis paradigm. It was anticipated, in line with risk homeostasis theory, that drivers would compensate for the reduction in risk by increasing speed. The results support the hypothesis although, after a simulated failure of the VE system, drivers did reduce their speed due to reduced confidence in the reliability of the system
Psychiatrists should investigate their patients less
Psychiatrists often order investigations such as blood tests, neuroimaging and electroencephalograms for their patients. Rationales include ruling out 'organic' causes of psychiatric presentations, providing baseline parameters before starting psychotropic medications, and screening for general cardiometabolic health. Hospital protocols often recommend an extensive panel of blood tests on admission to a psychiatric ward. In this Against the Stream article, we argue that many of these investigations are at best useless and at worst harmful: the yield of positive findings that change clinical management is extremely low; special investigations are a poor substitute for a targeted history and examination; and incidental findings may cause anxiety and further unwarranted investigation. Cognitive and cultural reasons why over-investigation continues are discussed. We conclude by encouraging a more targeted approach guided by a thorough bedside clinical assessment
Direct measurements of DOCO isomers in the kinetics of OD+CO
Quantitative and mechanistically-detailed kinetics of the reaction of
hydroxyl radical (OH) with carbon monoxide (CO) have been a longstanding goal
of contemporary chemical kinetics. This fundamental prototype reaction plays an
important role in atmospheric and combustion chemistry, motivating studies for
accurate determination of the reaction rate coefficient and its pressure and
temperature dependence at thermal reaction conditions. This intricate
dependence can be traced directly to details of the underlying dynamics
(formation, isomerization, and dissociation) involving the reactive
intermediates cis- and trans-HOCO, which can only be observed transiently.
Using time-resolved frequency comb spectroscopy, comprehensive mechanistic
elucidation of the kinetics of the isotopic analogue deuteroxyl radical (OD)
with CO has been realized. By monitoring the concentrations of reactants,
intermediates, and products in real-time, the branching and isomerization
kinetics and absolute yields of all species in the OD+CO reaction are
quantified as a function of pressure and collision partner.Comment: 19 pages, 4 figure
The Electronic Spectrum of Fullerenes from the Dirac Equation
The electronic spectrum of sheets of graphite (plane honeycomb lattice)
folded into regular polihedra is studied. A continuum limit valid for
sufficiently large molecules and based on a tight binding approximation is
derived. It is found that a Dirac equation describes the flat graphite lattice.
Curving the lattice by insertion of odd numbered rings can be mimicked by
coupling effective gauge fields. In particular the and related
molecules are well described by the Dirac equation on the surface of a sphere
coupled to a color monopole sitting at its center.Comment: 29 pages, 7 figures. IASSNS-HEP-92/5
Quality of life among adults following bariatric and body contouring surgery: a systematic review.
Background: Weight loss following bariatric surgery is associated with significant improvements in obesity-related comorbidities, body satisfaction and psychosocial outcomes, at least in the short term. However, in the context of extreme weight loss, body image and appearance may worsen again because the “excess” or “loose” skin can lead to both functional and profound dissatisfaction with appearance. These concerns have led to an increasing uptake of post-bariatric surgery, “body-contouring” procedures but the implications for quality of life (QoL) have not been thoroughly considered. Objective/purpose: The objective was to identify the best available evidence regarding the QoL outcomes for adults following bariatric and body contouring surgery. Inclusion criteria Types of participants: The review considered studies involving people aged 18 years and beyond who underwent bariatric surgery and body contouring surgery. Types of interventions: The review considered studies that evaluated bariatric surgery as well as body contouring surgery. Types of studies: The review considered both experimental and epidemiological study designs. Outcomes: The primary outcomes were QoL as measured by validated tools at less than two years, two to five years and more than five years following body contouring surgery. The secondary outcomes were adverse events, unsatisfactory aesthetic appearance and weight gain. Search strategy: Six databases were searched, including Cochrane Central, MEDLINE, Embase, Web of Science, PsycINFO and CINAHL. Studies published from 1954 to 2014 were considered. Additional searches for unpublished studies were undertaken in BIOSIS citation index, Register of Current Controlled Trials and Global Health Observatory. Methodological quality: The methodological quality of eligible studies was assessed independently by two reviewers using the Joanna Briggs Institute quality assessment tool. Data extraction: Data extraction from the included studies was undertaken and summarized independently by two reviewers using the standardized Joanna Briggs Institute data extraction tool. Data synthesis: Studies were too heterogeneous and could not be pooled in statistical meta-analysis. Therefore, the data results are presented as a narrative summary in relation to the outcomes of interest. Results: Nine quantitative studies (four comparable cohort studies, including two group design and two four-group designs and five descriptive or case-series studies) were included in the review. The included studies reported significant clinical improvements in appearance, wellbeing and QoL. These included primary outcomes pointing to body image satisfaction, improved self-esteem and confidence, improved physical function/pain and improved social function. The secondary outcomes were related to adverse events in the early postoperative period and reported wound healing problems, including seromas, partial necrosis, dehiscence, hematoma and anemia because of blood loss. Also, some data sets shed light on appearance-related distress and body dysphoria post surgery associated with visible scars and contour deformities. Conclusion: Body contouring surgery has been shown to have positive benefits, especially in relation to improved wellbeing, function and QoL. However, adjustment to changing body image following body contouring is both challenging and empowering and seems to be a transitional process
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