1,721 research outputs found
Economic Impacts of Aquatic Vegetation to Angling in Two South Carolina Reservoirs
Angler creel surveys and economic impact models were
used to evaluate potential expansion of aquatic vegetation in
Lakes Murray and Moultrie, South Carolina. (PDF contains 4 pages.
Positive-P and Wigner representations for quantum-optical systems with nonorthogonal modes
We generalize the basic concepts of the positive-P and Wigner representations to unstable quantum-optical systems that are based on nonorthogonal quasimodes. This lays the foundation for a quantum description of such systems, such as, for example an unstable cavity laser. We compare both representations by calculating the tunneling times for an unstable resonator optical parametric oscillator
Quantum statistics of overlapping modes in open resonators
We study the quantum dynamics of optical fields in weakly confining
resonators with overlapping modes. Employing a recently developed quantization
scheme involving a discrete set of resonator modes and continua of external
modes we derive Langevin equations and a master equation for the resonator
modes. Langevin dynamics and the master equation are proved to be equivalent in
the Markovian limit. Our open-resonator dynamics may be used as a starting
point for a quantum theory of random lasers.Comment: 6 pages, corrected typo
The Midpoint Rule as a Variational--Symplectic Integrator. I. Hamiltonian Systems
Numerical algorithms based on variational and symplectic integrators exhibit
special features that make them promising candidates for application to general
relativity and other constrained Hamiltonian systems. This paper lays part of
the foundation for such applications. The midpoint rule for Hamilton's
equations is examined from the perspectives of variational and symplectic
integrators. It is shown that the midpoint rule preserves the symplectic form,
conserves Noether charges, and exhibits excellent long--term energy behavior.
The energy behavior is explained by the result, shown here, that the midpoint
rule exactly conserves a phase space function that is close to the Hamiltonian.
The presentation includes several examples.Comment: 11 pages, 8 figures, REVTe
Successful Bronchoscopic Cryorecanalization in a Case of Endobronchial Lipoma
Endobronchial lipomas are rare benign tumors; less than 150 cases have been reported so far. Bronchial occlusion usually leads to a misdiagnosis of asthma/COPD or malignancy. We report the case of a 67-year-old man with a history of heavy smoking (100 pack years), dyspnea on exertion, cough, and malaise who was treated for pneumonia for three weeks. Due to nonresolving atelectasis of the superior segment of the right lower lobe, a malignant endobronchial tumor was suspected. Rigid bronchoscopy with cryorecanalization led to both the definite histopathological diagnosis of endobronchial lipoma and the reopening of an endoluminal airway obstruction during one procedure
The neutrophil: A key resourceful agent in immune-mediated vasculitis
The term “vasculitis” refers to a group of rare immune-mediated diseases characterized by the dysregulated immune system attacking blood vessels located in any organ of the body, including the skin, lungs, and kidneys. Vasculitides are classified according to the size of the vessel that is affected. Although this observation is not specific to small-, medium-, or large-vessel vasculitides, patients show a high circulating neutrophil-to-lymphocyte ratio, suggesting the direct or indirect involvement of neutrophils in these diseases. As first responders to infection or inflammation, neutrophils release cytotoxic mediators, including reactive oxygen species, proteases, and neutrophil extracellular traps. If not controlled, this dangerous arsenal can injure the vascular system, which acts as the main transport route for neutrophils, thereby amplifying the initial inflammatory stimulus and the recruitment of immune cells. This review highlights the ability of neutrophils to “set the tone” for immune cells and other cells in the vessel wall. Considering both their long-established and newly described roles, we extend their functions far beyond their direct host-damaging potential. We also review the roles of neutrophils in various types of primary vasculitis, including immune complex vasculitis, anti-neutrophil cytoplasmic antibody-associated vasculitis, polyarteritis nodosa, Kawasaki disease, giant cell arteritis, Takayasu arteritis, and Behçet's disease
Prevalence and burden of chronic bronchitis symptoms: results from the BOLD study
We studied the prevalence, burden and potential risk factors for chronic bronchitis symptoms in the Burden of Obstructive Lung Disease study. Representative population-based samples of adults aged ≥40 years were selected in participating sites. Participants completed questionnaires and spirometry. Chronic bronchitis symptoms were defined as chronic cough and phlegm on most days for ≥3 months each year for ≥2 years. Data from 24 855 subjects from 33 sites in 29 countries were analysed. There were significant differences in the prevalence of self-reported symptoms meeting our definition of chronic bronchitis across sites, from 10.8% in Lexington (KY, USA), to 0% in Ile-Ife (Nigeria) and Blantyre (Malawi). Older age, less education, current smoking, occupational exposure to fumes, self-reported diagnosis of asthma or lung cancer and family history of chronic lung disease were all associated with increased risk of chronic bronchitis. Chronic bronchitis symptoms were associated with worse lung function, more dyspnoea, increased risk of respiratory exacerbations and reduced quality of life, independent of the presence of other lung diseases. The prevalence of chronic bronchitis symptoms varied widely across the studied sites. Chronic bronchitis symptoms were associated with significant burden both in individuals with chronic airflow obstruction and those with normal lung function
Implementation of alternative intersections in South Africa : operational conundrum or cost effective infrastructure solution
The existing Diamond Interchange at the crossing of the N1 with Sefako Makghato Drive (Route K14) in the City of Tshwane Metropolitan Municipality was recently, in 2015, upgraded to a Diverging Diamond Interchange (DDI). The Diverging Diamond Interchange is one of the so-called alternative intersections based on innovative approaches to avoid or minimise opposing traffic flows. The paper presents the results of capacity and operational analyses by means of analytical techniques (SIDRA 7.0 Plus), and also evaluates the cost-effectiveness. Typical operational challenges of the urban environment, i.e. non-motorised transport, disorderly taxi behaviour, power outages, etc. were also addressed.Papers presented at the 36th Southern African Transport Conference, CSIR International Convention Centre, Pretoria, South Africa on 10-13 July 2017.Transportation research board of the national academie
Quantum Langevin theory of excess noise
In an earlier work [P. J. Bardroff and S. Stenholm], we have derived a fully
quantum mechanical description of excess noise in strongly damped lasers. This
theory is used here to derive the corresponding quantum Langevin equations.
Taking the semi-classical limit of these we are able to regain the starting
point of Siegman's treatment of excess noise [Phys. Rev. A 39, 1253 (1989)].
Our results essentially constitute a quantum derivation of his theory and allow
some generalizations.Comment: 9 pages, 0 figures, revte
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