3,156 research outputs found
DSS-13 26-meter antenna upgraded radiometer system
The Deep Space Station (DSS)-13 26-m antenna radiometer system was upgraded with an IBM-compatible computer-controlled configuration with improved supporting hardware and software. Software was generated to analyze results and correct for antenna mispointing, tropospheric loss, and other observing errors. This total power radiometer configuration provides a prototype for the new DSS-13 34-m antenna. The radiometer system is described in terms of the theory, instrumentation hardware, computer configuration, and operational features and performance. The system is used to obtain antenna efficiency and pointing model data and is useful for radio source calibrations required for radio astronomy. Some recent results are given
Differential Uptake of Gold Nanoparticles by 2 Species of Tadpole, the Wood Frog (Lithobates Sylvaticus) and the Bullfrog (Lithobates Catesbeianus)
Engineered nanoparticles are aquatic contaminants of emerging concern that exert ecotoxicological effects on a wide variety of organisms. We exposed cetyltrimethylammonium bromide–capped spherical gold nanoparticles to wood frog and bullfrog tadpoles with conspecifics and in combination with the other species continuously for 21 d, then measured uptake and localization of gold. Wood frog tadpoles alone and in combination with bullfrog tadpoles took up significantly more gold than bullfrogs. Bullfrog tadpoles in combination with wood frogs took up significantly more gold than controls. The rank order of weight-normalized gold uptake was wood frogs in combination \u3e wood frogs alone \u3e bullfrogs in combination \u3e bullfrogs alone \u3e controls. In all gold-exposed groups of tadpoles, gold was concentrated in the anterior region compared with the posterior region of the body. The concentration of gold nanoparticles in the anterior region of wood frogs both alone and in combination with bullfrogs was significantly higher than the corresponding posterior regions. We also measured depuration time of gold in wood frogs. After 21 d in a solution of gold nanoparticles, tadpoles lost \u3e83% of internalized gold when placed in gold-free water for 5 d. After 10 d in gold-free water, tadpoles lost 94% of their gold. After 15 d, gold concentrations were below the level of detection. Our finding of differential uptake between closely related species living in similar habitats with overlapping geographical distributions argues against generalizing toxicological effects of nanoparticles for a large group of organisms based on measurements in only one species
Soluble and cell-associated transferrin receptor in lung cancer.
The expression of transferrin receptor (TfR) has been identified in many malignant tumours. In lung cancer, lymphoma and breast cancer, it has been shown that the expression of TfR correlates with tumour differentiation, probably implying some prognostic value. A soluble form of TfR (sTfR) in human serum has been shown to be proportional to the number of cellular TfRs. Based on these data we examined the utility of measuring sTfR in the serum and bronchoalveolar lavage (BAL) fluid of patients with lung cancer (n = 32) and patients with chronic obstructive pulmonary disease (n = 22). BAL fluid was centrifuged to separate the supernatant from the cellular component. Cells were lysed in a detergent and cell-associated TfR was measured by enzyme-linked immunosorbent assay (ELISA) and expressed as ng 10(-6) cells in this cellular component. There was no difference in serum sTfR between the cancer and chronic obstructive pulmonary disease (COPD) groups. A higher level of cell-associated TfR was found in BAL of non-small-cell lung cancer patients than in COPD patients (P = 0.01). The calculated number of TfR molecules per cell in BAL correlated positively with the percentage of macrophages in BAL (P < 0.0001), suggesting that cell-associated TfR in BAL originates primarily from macrophages in this fluid. No correlation existed between BAL cell-associated TfR and tumour size, nodal status, the presence of metastases and serum sTfR. BAL cell-associated TfR was negatively correlated with BAL supernatant neuron-specific enolase (NSE) (P = 0.01). A combination of BAL supernatant NSE and cell-associated TfR detected lung cancer with a sensitivity of 91%, a specificity of 59% and positive and negative predictive values of 81% and 71% respectively. In conclusion, BAL cell-associated TfR may help in the differential diagnosis of lung cancer vs pneumonia
Application of a lumped parameter code for prediction of hydrogen distribution within containments of water reactors
Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.The lumped parameter code HEPCAL has been worked out in the Institute of Thermal Technology of the Silesian University of Technology for simulations of pressurized water reactor containments response to accidental conditions, especially during loss-of-coolant accidents (LOCA). Within the framework of this work the HEPCAL code has been applied for simulations of hydrogen behavior within containments of Advanced Boiling Water Reactor (ABWR) and European Pressurized Reactor (EPR). The focus has been put on hydrogen distribution thorough subcompartments of the containment building. A dynamics of creating flammable mixtures and operation of hydrogen removal systems were also the subjects of analysis.cf201
U.S. stock market interaction network as learned by the Boltzmann Machine
We study historical dynamics of joint equilibrium distribution of stock
returns in the U.S. stock market using the Boltzmann distribution model being
parametrized by external fields and pairwise couplings. Within Boltzmann
learning framework for statistical inference, we analyze historical behavior of
the parameters inferred using exact and approximate learning algorithms. Since
the model and inference methods require use of binary variables, effect of this
mapping of continuous returns to the discrete domain is studied. The presented
analysis shows that binarization preserves market correlation structure.
Properties of distributions of external fields and couplings as well as
industry sector clustering structure are studied for different historical dates
and moving window sizes. We found that a heavy positive tail in the
distribution of couplings is responsible for the sparse market clustering
structure. We also show that discrepancies between the model parameters might
be used as a precursor of financial instabilities.Comment: 15 pages, 17 figures, 1 tabl
Statistical pairwise interaction model of stock market
Financial markets are a classical example of complex systems as they comprise
many interacting stocks. As such, we can obtain a surprisingly good description
of their structure by making the rough simplification of binary daily returns.
Spin glass models have been applied and gave some valuable results but at the
price of restrictive assumptions on the market dynamics or others are
agent-based models with rules designed in order to recover some empirical
behaviours. Here we show that the pairwise model is actually a statistically
consistent model with observed first and second moments of the stocks
orientation without making such restrictive assumptions. This is done with an
approach based only on empirical data of price returns. Our data analysis of
six major indices suggests that the actual interaction structure may be thought
as an Ising model on a complex network with interaction strengths scaling as
the inverse of the system size. This has potentially important implications
since many properties of such a model are already known and some techniques of
the spin glass theory can be straightforwardly applied. Typical behaviours, as
multiple equilibria or metastable states, different characteristic time scales,
spatial patterns, order-disorder, could find an explanation in this picture.Comment: 11 pages, 8 figure
Darboux transformations, finite reduction groups and related Yang-Baxter maps
In this paper we construct Yang-Baxter (YB) maps using Darboux matrices which
are invariant under the action of finite reduction groups. We present
6-dimensional YB maps corresponding to Darboux transformations for the
Nonlinear Schr\"odinger (NLS) equation and the derivative Nonlinear
Schr\"odinger (DNLS) equation. These YB maps can be restricted to
dimensional YB maps on invariant leaves. The former are completely
integrable and they also have applications to a recent theory of maps
preserving functions with symmetries \cite{Allan-Pavlos}. We give a
dimensional YB-map corresponding to the Darboux transformation for a
deformation of the DNLS equation. We also consider vector generalisations of
the YB maps corresponding to the NLS and DNLS equation.Comment: 18 pages, revised version. The format of the paper has changed, we
added one sectio
Contribution of positron emission tomography in pleural disease.
INTRODUCTION: Positron emission tomography (PET) now plays a clear role in oncology, especially in chest tumours. We discuss the value of metabolic imaging in characterising pleural pathology in the light of our own experience and review the literature. BACKGROUND: PET is particularly useful in characterising malignant pleural pathologies and is a factor of prognosis in mesothelioma. Metabolic imaging also provides clinical information for staging lung cancer, in researching the primary tumour in metastatic pleurisy and in monitoring chronic or recurrent pleural pathologies. CONCLUSIONS: PET should therefore be considered as a useful tool in the diagnosis of liquid or solid pleural pathologies
Evaluating Lifeworld as an emancipatory methodology
Disability research is conducted within a highly politicised ‘hotbed’ of competing paradigms and principles. New researchers, who want to work within the social model, are soon faced with complex and challenging methodological and philosophical dilemmas. The social model advocates research agendas that are focused on the emancipation and empowerment of disabled people but, in reality, these are rarely achieved. To be successful researchers need to engage with innovative and creative methodologies and to share their experiences of these within environments that welcome challenge and debate. This paper focuses on Lifeworld and assesses its value as a tool for emancipatory research. Using examples from a study with parents, whose children were in the process of being labelled as having autism, the paper illustrates how the principles that ‘underpin’ the methodology offered a supportive framework for a novice researcher
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