Enhanced fluorescent immunoassays on silver fractal-like structures

Using the effect of the fluorescence enhancement in close proximity to metal nanostructures, we have been able to demonstrate ultrasensitive immunoassays suitable for the detection of biomarkers. Silver fractal-like structures have been grown by electrochemical reduction of silver on the surface of glass slides. A model immunoassay was performed on the slide surface with rabbit IgG (antigen) noncovalently immobilized on the slide, and rhodamine red-X-labeled antirabbit IgG conjugate was subsequently bound to the immobilized antigen. The fluorescence signal was measured from the glass-fractal's surface using a confocal microscope, and the images were compared to the images from the same surface not coated with fractals. Our results showed significant enhancement (more than 100-fold) of the signal detected on fractals compared to bare glass. We thus demonstrate that such fractal-like structures can assist in improving the signals from assays used in medical diagnostics, especially those for analytes with molecular weight under 100 kDa.     

Quantum conductance of silicon-doped carbon wire nanojunctions

Unknown quantum electronic conductance across nanojunctions made of silicon-doped carbon wires between carbon leads is investigated. This is done by an appropriate generalization of the phase field matching theory for the multi-scattering processes of electronic excitations at the nanojunction and the use of the tight-binding method. Our calculations of the electronic band structures for carbon, silicon, and diatomic silicon carbide are matched with the available corresponding density functional theory results to optimize the required tight-binding parameters. Silicon and carbon atoms are treated on the same footing by characterizing each with their corresponding orbitals. Several types of nanojunctions are analyzed to sample their behavior under different atomic configurations. We calculate for each nanojunction the individual contributions to the quantum conductance for the propagating σ, Π, and σ^∗electron incidents from the carbon leads. The calculated results show a number of remarkable features, which include the influence of the ordered periodic configurations of silicon-carbon pairs and the suppression of quantum conductance due to minimum substitutional disorder and artificially organized symmetry on these nanojunctions. Our results also demonstrate that the phase field matching theory is an efficient tool to treat the quantum conductance of complex molecular nanojunctions.     

Heat transfer to longitudinal laminar flow between thin cylinders

The forced-convection longitudinal flow of a viscous and heat-conducting fluid in a system of thin parallel cylinders, arranged in regular patterns, is studied. The aim of the study is to determine both the velocity field and temperature field between the system of thin cylinders. A new way of calculating i.e. the use of a complex number is proposed. The final results are analytical formulas for determining the longitudinal permeability and the Nusselt number of the fluid and the system of thin cylinders.     

On Nonparametric Identification of Wiener Systems

In this paper, a new method for the identification of the Wiener nonlinear system is proposed. The system, being a cascade connection of a linear dynamic subsystem and a nonlinear memoryless element, is identified by a two-step semiparametric approach. The impulse response function of the linear part is identified via the nonlinear least-squares approach with the system nonlinearity estimated by a pilot nonparametric kernel regression estimate. The obtained estimate of the linear part is then used to form a nonparametric kernel estimate of the nonlinear element of the Wiener system. The proposed method permits recovery of a wide class of nonlinearities which need not be invertible. As a result, the proposed algorithm is computationally very efficient since it does not require a numerical procedure to calculate the inverse of the estimate. Furthermore, our approach allows non-Gaussian input signals and the presence of additive measurement noise. However, only linear systems with a finite memory are admissible. The conditions for the convergence of the proposed estimates are given. Computer simulations are included to verify the basic theory     

Violations of chemotherapy protocols for ovarian cancer--reasons and consequences

In times when colony-stimulating factors were not available, delays of treatment or dose reductions were necessary, to assure that chemotherapy could be safely administered. In a retrospective analysis the effects of chemotherapy protocol violations on the survival of patients with ovarian cancer was evaluated. The serial courses of leukocyte counts were often the determinants for a protocol adequate chemotherapy in contrary to the thrombocytes but the serial platelet counts had no influence on protocol violations. Only time-related protocol violations have been found in 7.6% of the cases. There seems to be no apparent influence on patients' survival. However, accomplishment of treatment schedules, which may be regarded as a reaction towards unsatisfactory tumour response, at the initial visit alone or in combination with time-related protocol violations as well as tumour stage, course of tumour markers (CA 125) had a strong impact on survival while higher dosage levels produces only a trend towards improved survival. The use of growth factors will probably reduce the percentage of protocol violations caused by neutropenia, but it is questionable if it will reduce mortality due to tumour progression.     

Patterns of primary and heterotrophic productivity in an arid lowland river

Three river conceptual models make differing predictions about the major source of primary production in lowland rivers, acknowledging the importance of primary productivity in the ecology and management of lowland rivers. Patterns of primary production in lowland rivers are still an area of considerable uncertainty. The objective of this study was to examine the major sources and transformations of organic matter in an Australian lowland river and compare them to the predictions of existing models. The broad approach adopted was to quantify the contribution from the major ecosystem components and compare these with estimates of system metabolism determined using open water measures of diel oxygen change. Three 4‐km river reaches were selected to represent the extent of variation found along the free‐flowing lowland sections of the Murray River, one of Australia's largest and most regulated rivers. Annual open water gross primary production (GPP) estimates for the Murray R. during this study ranged from 221 to 376 gC m^?2 y^?1 and were similar to other large rivers. Examination of the net contribution of organic matter to the channel indicates that primary productivity in the Murray R. is derived from a combination of phytoplankton, riparian vegetation and macrophytes, but that the major source varies both spatially and temporally. The present study confirms that the River Continuum Concept (RCC), the Flood Pulse Concept (FPC) and Riverine Productivity Model (RPM) all have some application to Australian lowland rivers, but that synthesis of the models will be difficult until we can incorporate the extent, causes and consequences of primary production variability. This study also highlights the importance of the microbial loop and macrophytes in the ecology of the Murray R. Copyright © 2007 John Wiley & Sons, Ltd.     

Ziegler–Natta catalysts based on vanadium halides: a DFT study

Ziegler–Natta ethylene insertion into the carbon–metal bond for a number of fragments containing vanadium on different oxidation states as well as the halogen ligands has been studied by means of DFT. It is shown that the complexation and insertion energies are strongly influenced by the charge on the transition metal atom and, to some extent, by the electronegativity of the halogen atom. Complexation energy varies in the range −129 to −159 kJ/mol for charged species and −64 to −77 kJ/mol for neutral ones. Insertion energy follows a similar pattern and ranges from −28 to −62 and −82 to −100 kJ/mol, respectively. The calculated values are compared with the experimental results and different activities of catalysts based on VX₃ (where X denotes a halogen atom) are accounted for. Discussion of certain structural features of active sites, transition states and products is also given.     

Maritime surveillance: Tracking ships inside a dynamic background using a fast level-set

Surveillance in a maritime environment is indispensable in the fight against a wide range of criminal activities, including pirate attacks, unlicensed fishing trailers and human trafficking. Computer vision systems can be a useful aid in the law enforcement process, by for example tracking and identifying moving vessels on the ocean. However, the maritime domain poses many challenges for the design of an effective maritime surveillance system. One such challenge is the tracking of moving vessels in the presence of a moving dynamic background (the ocean). We present techniques that address this particular problem. We use a background subtraction method and employ a real-time approximation of level-set-based curve evolution to demarcate the outline of moving vessels in the ocean. We report promising results on both small and large vessels, based on two field trials.     

The Use of Context-Free Probabilistic Grammar to Anonymise Statistical Data

Abstract

In the following article, a proprietary method of anonymisation of identifiable statistical data using context-free probabilistic grammar is proposed. The advantage of this method is that it is simple and thanks to this, the identifier is easy to retrieve after masking the identifiable data, e.g. when it is necessary to modify or update the micro-data. This can be done using public-key cryptography, i.e. encrypting some probabilistic context-free grammar with this method. In the case of public statistics, there is often a need to use an anonymised source value, for example when economic operators’ reports are verified by statistical officers. With appropriate information generated by context-free grammar, the verifier can easily identify an economic operator or a natural person. The idea of the anonymising algorithm used in the proposed method is presented by means of an example. According to the authors, the combination of the proposed method with asymmetric encryption of the definition of context-free grammar using public key infrastructure, makes it probable that its resistance to attacks will be quite high. This is because statistical methods that are used in the analysis of natural languages are not susceptible to attacks.     

Marine and farmed fish in the Polish market: Comparison of the nutritional value

The proximate composition and fatty acids profiles of the muscle tissues of nine fish species that are popular on the Polish market were examined. The nine studied fish species were: Baltic fish (cod, herring, salmon), fish farmed in Poland (carp, trout), oceanic fish imported from China (walleye pollock, sole), and farmed fish imported from Vietnam and China (sutchi catfish, tilapia). The lowest lipid content (below 0.1%) was noted in the muscle tissues of Baltic cod and walleye pollock caught in the Pacific. The muscle tissue of walleye pollock also had the lowest protein content (12.2 ± 2.0%). The highest lipid content was noted in the muscle tissues of Baltic salmon (13.1 ± 2.4%). The highest percentage content of eicosapentaenoic (C20:5 n − 3 – EPA) and docosahexaenoic (C22:6 n − 3 – DHA) acids (over 40%) was noted in the fat extracted from the oceanic fish and Baltic cod. However, due to the low fat content, the concentrations of EPA + DHA in these fish species and in imported farmed fish expressed in mg/100 g of muscle tissues are the lowest and range on average from 24.8 ± 5.7 mg/100 g (sutchi catfish) to 207.4 ± 125.4 mg/100 g (sole). This is why the consumption of these fish species has no significant meaning for coronary heart disease prevention. Consumers with symptoms of cardiovascular diseases should include the following fish species, which have high concentrations of EPA + DHA: Baltic salmon (3807.2 ± 666.3 mg/100 g); Polish farmed trout (1804.0 ± 279.2 mg/100 g); and Baltic herring (940.9 ± 306.6 mg/100 g) in their diets. However, the consumption of Baltic salmon must be limited on account of the levels of persistent organic pollutants found in it.