Institute of Mathematics

Hospital effluents represent an important source for the release of antibiotics and antibiotic resistant bacteria into the environment. This study aims to determine concentrations of various antibiotics in wastewater before and after wastewater treatment in a rural hospital (60 km from the center of Hanoi) and in an urban hospital (in the center of Hanoi) in Vietnam, and it aims to explore the relationship between antibiotic concentrations in wastewater before wastewater treatment and quantities of antibiotics used in the rural hospital, over a period of one year in 2013. Water samples were collected using continuous sampling for 24 h in the last week of every month. The data on quantities of antibiotics delivered to all inpatient wards were collected from the Pharmacy department in the rural hospital. Solid-phase extraction and high performance liquid chromatography-tandem mass spectrometry were used for chemical analysis. Significant concentrations of antibiotics were present in the wastewater both before and after wastewater treatment of both the rural and the urban hospital. Ciprofloxacin was detected at the highest concentrations in the rural hospital's wastewater (before treatment: mean = 42.8 µg/L; after treatment: mean = 21.5 µg/L). Metronidazole was detected at the highest concentrations in the urban hospital's wastewater (before treatment: mean = 36.5 µg/L; after treatment: mean = 14.8 µg/L). A significant correlation between antibiotic concentrations in wastewater before treatment and quantities of antibiotics used in the rural hospital was found for ciprofloxacin (r = 0.78; p = 0.01) and metronidazole (r = 0.99; p < 0.001).

Abstract The analytical theory governing the propagation of spiral laser beams in nonlinear media is developed. It is shown that, taking into account the saturation effect in a Kerr medium, spiral beams have a tube-like structure with a periodicity along the axis of a nonlinear autoguide. In the case of the absence of saturation mechanism the collapse of spiral beams is described. It is found that critical autoguide power depends on the topological charge of the spiral beam. The stability of a circular symmetry structure of the beam is investigated. The analytical results are in good agreement with the numerical experiment.

BACKGROUND: Considerable differences exist among the living donor Kidney Exchange Programmes (KEPs) that are in use and being built in Europe, contributing to a variation in the number of living donor transplants (Newsletter Transplant; International figures on donation and transplantation 2016). Efforts of European KEPs to exchange (best) practices and share approaches to address challenges have, however, been limited. METHODS: Experts from 23 European countries, collaborating on the European Network for Collaboration on Kidney Exchange Programmes Cooperation on Science and Technology Action, developed a questionnaire to collect detailed information on the functioning of all existing KEPs in Europe, as well as their opportunities and challenges. Following a comparative analysis, results were synthesized and interpreted by the same experts. RESULTS: The practices, opportunities and challenges reported by 17 European countries reveal that some of the 10 operating programs are mature, whereas others are in earlier stages of development. Over 1300 transplants were performed through existing KEPs up to the end of 2016, providing approximately 8% of their countries' living kidney donations in 2015. All countries report challenges to either initiating KEPs or increasing volumes. Some challenges are shared, whereas others differ because of differences in context (eg, country size, effectiveness of deceased donor program) and ethical and legal considerations (eg, regarding living donation as such, nonrelated donors, and altruistic donation). Transnational initiatives have started in Central Europe, Scandinavia, and Southern Europe. CONCLUSIONS: Exchange of best practices and shared advancement of national programs to address existing challenges, aided by transnational exchanges, may substantially improve access to the most (cost) effective treatment for the increasing number of patients suffering from kidney disease.

Throughout this paper, A denotes a noetherian local ring with maximal ideal m and M a finitely generated A -module with d : = dim M ≥1.

A total edge-irregular k-labelling : V (G) E(G) {1, 2, . . . , k} of a graph G is a labelling of vertices and edges of G in such a way that for any different edges e and f their weights wt(e) and wt(f ) are distinct. The weight wt(e) of an edge e = xy is the sum of the labels of vertices x and y and the label of the edge e. The minimum k for which a graph G has a total edge-irregular k-labelling is called the total edge irregularity strength of G, tes(G). In this paper we prove that for every tree T of maximum degree on p vertices tes(T ) = max{ (p + 1)/3 , ( + 1)/2 }.

A series of novel tacrine derivatives and tacrine-coumarin heterodimers were designed, synthesized, and biologically evaluated for their potential inhibitory effect on both acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). Of these compounds, tacrine-coumarin heterodimer 7c and tacrine derivative 6b were found to be the most potent inhibitors of human AChE (hAChE), demonstrating IC50 values of 0.0154 and 0.0263 μM. Ligands 6b, 6c, and 7c exhibited the highest levels of inhibitory activity against human BuChE (hBuChE), demonstrating IC50 values that range from 0.228 to 0.328 μM. Docking studies were performed in order to predict the binding modes of compounds 6b and 7c with hAChE/hBuChE.

Previously we showed L-4F, a novel apolipoprotein A-I (apoA-I) mimetic, improved vasodilation in 2 dissimilar models of vascular disease: hypercholesterolemic LDL receptor-null (Ldlr(-/-)) mice and transgenic sickle cell disease mice. Here we determine the mechanisms by which D-4F improves vasodilation and arterial wall thickness in hypercholesterolemic Ldlr(-/-) mice and Ldlr(-/-)/apoA-I null (apoA-I(-/-)), double-knockout mice. Ldlr(-/-) and Ldlr(-/-)/apoA-I(-/-) mice were fed Western diet (WD) with and without D-4F. Oral D-4F restored endothelium- and endothelial NO synthase (eNOS)-dependent vasodilation in direct relationship to duration of treatments and reduced wall thickness in as little as 2 weeks in vessels with preexisting disease in Ldlr(-/-) mice. D-4F had no effect on total or HDL cholesterol concentrations but reduced proinflammatory HDL levels. D-4F had no effect on plasma myeloperoxidase concentrations but reduced myeloperoxidase association with apoA-I as well as 3-nitrotyrosine in apoA-I. D-4F increased endothelium- and eNOS-dependent vasodilation in Ldlr(-/-)/apoA-I(-/-) mice but did not reduce wall thickness as it had in Ldlr(-/-) mice. Vascular endothelial cells were treated with 22(R)-hydroxycholesterol with and without L-4F. 22(R)-Hydroxycholesterol decreased NO (*NO) and increased superoxide anion (O2*-) production and increased ATP-binding cassette transporter-1 and collagen expression. L-4F restored *NO and O2*- balance, had little effect on ATP-binding cassette transporter-1 expression, but reduced collagen expression. These data demonstrate that although D-4F restores vascular endothelial cell and eNOS function to increase vasodilation, HDL containing apoA-I, or at least some critical concentration of the antiatherogenic lipoprotein, is required for D-4F to decrease vessel wall thickness.

Infection with human papillomaviruses (HPVs) is one of the most common sexually transmitted infections and can lead to development of head and neck, skin, and anogenital cancer, including cervical cancer, which represents one of the world's most significant health problems. In this study, we analyze G-rich regions in all known HPV genomes in order to evaluate their potential to fold into G-quadruplex structure. Interestingly, G-rich loci fulfilling the criteria for G-quadruplex formation were found in only 8 types of HPV. Nevertheless, viral G-quadruplexes in 7 sequences derived directly from HPVs are confirmed here for the first time. G-rich regions with the capacity to form G-quadruplexes are located in the LCR, L2, E1, and E4 regions of the HPV genome; therefore we assume that regulation processes in viruses could be affected by G-quadruplex formation. Our results represent a starting point for the design of specific ligands with viral G-quadruplex motifs and suggest novel methods for the control of viral replication and transcription.

The main objective of this paper is to prove a Khintchine type theorem for divergence for linear Diophantine approximation on non-degenerate manifolds, which completes earlier results for convergence.

(1989). When is the rees algebra cohen—macaulay? Communications in Algebra: Vol. 17, No. 12, pp. 2893-2922.

Abstract We address the following problem: given a set of complex images or a large database, the numerical and computational complexity and quality of approximation for neural network may drastically differ from one activation function to another. A general novel methodology, scaled polynomial constant unit activation function “SPOCU,” is introduced and shown to work satisfactorily on a variety of problems. Moreover, we show that SPOCU can overcome already introduced activation functions with good properties, e.g., SELU and ReLU, on generic problems. In order to explain the good properties of SPOCU, we provide several theoretical and practical motivations, including tissue growth model and memristive cellular nonlinear networks. We also provide estimation strategy for SPOCU parameters and its relation to generation of random type of Sierpinski carpet, related to the [ pppq ] model. One of the attractive properties of SPOCU is its genuine normalization of the output of layers. We illustrate SPOCU methodology on cancer discrimination, including mammary and prostate cancer and data from Wisconsin Diagnostic Breast Cancer dataset. Moreover, we compared SPOCU with SELU and ReLU on large dataset MNIST, which justifies usefulness of SPOCU by its very good performance.

Abstract This study explored the associations between adolescents’ assertive behavior, psychological well‐being, and self‐esteem. The sample consisted of 1,023 students (14.9 ± .51; 47.6% boys). Two dimensions of the Scale for Interpersonal Behavior (distress and performance), 2 factors of the General Health Questionnaire‐12 (depression/anxiety and social dysfunction), and 2 factors of the R osenberg Self‐Esteem Scale (positive self‐esteem and negative self‐esteem) were used; data were analyzed using hierarchical linear regression. It was found that (a) the more anxious respondents felt in assertive situations, the less frequently they engaged in these situations; and that (b) both dimensions of assertiveness were associated with psychological well‐being and self‐esteem.

Multimedia documents are different from traditional text documents, because they may contain encodings of raw sensorical data. This fact has severe consequences for the efficient indexing and retrieval of information from documents in large unstructured collections (e.g. WWW), because it is very difficult to automatically identify generic meanings from visual or audible objects. A novel method for image retrieval from large collections is proposed in this paper. The method is based on color co-occurrence descriptors that utilize compact representations of essential information of the visual image content. The set of descriptor elements represents "elementary" color segments, their borders, and their mutual spatial distribution on the image frame. Such representation is flexible enough to describe image scenes ranging from simple combinations of color segments to high frequency color textures equally well. At the retrieval stage the comparison between a given query descriptor and the database descriptors is performed by a similarity measure. Image descriptors are robust versus affine transformations and several other image distortions. The consideration of the descriptors as sets of elements allows the combination of several images or subimages into a single query. Basic properties of the method are demonstrated experimentally on an image database containing 20000 images.

This article provides a quantitative analysis of peer review as an emerging field of research by revealing patterns and connections between authors, fields and journals from 1950 to 2016. By collecting all available sources from Web of Science, we built a dataset that included approximately 23,000 indexed records and reconstructed collaboration and citation networks over time. This allowed us to trace the emergence and evolution of this field of research by identifying relevant authors, publications and journals and revealing important development stages. Results showed that while the term "peer review" itself was relatively unknown before 1970 ("referee" was more frequently used), publications on peer review significantly grew especially after 1990. We found that the field was marked by three development stages: (1) before 1982, in which most influential studies were made by social scientists; (2) from 1983 to 2002, in which research was dominated by biomedical journals, and (3) from 2003 to 2016, in which specialised journals on science studies, such as Scientometrics, gained momentum frequently publishing research on peer review and so becoming the most influential outlets. The evolution of citation networks revealed a body of 47 publications that form the main path of the field, i.e., cited sources in all the most influential publications. They could be viewed as the main corpus of knowledge for any newcomer in the field.

A broadband tunable absorber is designed and fabricated. The tunable absorber is comprised of a dielectric-metal-dielectric multilayer and plasmonic grating. A large size of tunable absorber device is fabricated by nano-imprinting method. The experimental results show that over 90% absorption can be achieved within visible and near-infrared regimes. Moreover, the high absorption can be controlled by changing the polarization of incident light. This polarization-sensitive tunable absorber can have practical applications such as high-efficiency polarization detectors and transmissive polarizer.

High-altitude and alpine areas are predicted to experience rapid and substantial increases in future temperature, which may have serious impacts on soil carbon, nutrient and soil fauna. Here we report the impact of 20 years of experimental warming on soil properties and soil mites in three contrasting plant communities in alpine/subarctic Sweden. Long-term warming decreased juvenile oribatid mite density, but had no effect on adult oribatids density, total mite density, any major mite group or the most common species. Long-term warming also caused loss of nitrogen, carbon and moisture from the mineral soil layer in mesic meadow, but not in wet meadow or heath or from the organic soil layer. There was a significant site effect on the density of one mite species, Oppiella neerlandica, and all soil parameters. A significant plot-scale impact on mites suggests that small-scale heterogeneity may be important for buffering mites from global warming. The results indicated that juvenile mites may be more vulnerable to global warming than adult stages. Importantly, the results also indicated that global warming may cause carbon and nitrogen losses in alpine and tundra mineral soils and that its effects may differ at local scale.

Pentatomid bugs communicate using substrate-borne vibrational signals that are transmitted along herbaceous plant stems in the form of bending waves with a regular pattern of minimal and maximal amplitude values with distance. We tested the prediction that amplitude variation is caused by resonance, by measuring amplitude profiles of different vibrational pulses transmitted along the stem of a Cyperus alternifolius plant, and comparing their patterns with calculated spatial profiles of corresponding eigenfrequencies of a model system. The measured distance between nodes of the amplitude pattern for pulses with different frequencies matches the calculated values, confirming the prediction that resonance is indeed the cause of amplitude variation in the studied system. This confirmation is supported by the resonance profile obtained by a frequency sweep, which matches theoretical predictions of the eigenfrequencies of the studied system. Signal bandwidth influences the amount of amplitude variation. The effect of both parameters on signal propagation is discussed in the context of insect vibrational communication.

Two approaches to the characterization of three-dimensional (3-D) textures are presented: one based on gradient vectors and one on generalized co-occurrence matrices. They are investigated with the help of simulated data for their behavior in the presence of noise and for various values of the parameters they depend on. They are also applied to several medical volume images characterized by the presence of microtextures and their potential as diagnostic tools and tools for quantifying and monitoring the progress of various pathologies is discussed. No firm medical conclusions can be drawn as not enough clinical data are available. The gradient based method appears to be more appropriate for the characterization of microtextures. It also shows more consistent behavior as a descriptor of pathologies than the generalized co-occurrence matrix approach.

Tissue samples from nine red foxes (four samples of striated muscle tissue and five samples of heart tissue) that originated from the Michalovce district (Slovakia), an area with endemic occurrence of canine babesiosis were examined by PCR method using primers amplifying a fragment of the 18S rRNA spanning the V4 region of Babesia and Theileria. An unexpected determination of 450 bp DNA fragment of Hepatozoon canis was found in four samples. Partial sequences of the 18S rRNA gene from the H. canis showed 100% similarity with the sequence from Brasil isolate of H. canis from a pampas fox (Pseudalopex gymnocercus) (AY471615) as well as from a fox in Spain (AY150067) and from a dog in Brazil (AY864677). In the present study, we report the first PCR detection of Hepatozoon canis in a naturally infected red fox from Slovakia, a Rhipicephalus sanguineus-free region. We assume that the infection was spread by infected R. sanguineus that might have been brought to Slovakia by travelers, by golden jackals, or by foxes migrating because of expansion of golden jackals and environmental and climate changes.

G-Rich DNA and RNA have a higher propensity to form G-quadruplex structures, but the presence of G-runs alone is not sufficient to prove that such sequences can form stable G-quadruplexes. While G-rich sequences are essential for G-quadruplex formation, not all G-rich sequences have the propensity to form G-quadruplex structures. In addition, monovalent metal ions, dehydrating agents, and loop sequences connecting the G-runs also play important roles in the topology of G-quadruplex folding. To date, no quantitative analysis of the CD spectra of G-quadruplexes in confrontation with the electrophoretic results has been performed. Therefore, in this study, we use information gained through the analysis of a series of well-known G-quadruplex-forming sequences to evaluate other less-studied sets of aptameric sequences. A simple and cost-effective methodology that can verify the formation of G-quadruplex motifs from oligomeric DNA sequences and a technique to determine the molecularity of these structures are also described. This methodology could be of great use in the prediction of G-quadruplex assembly, and the basic principles of our techniques can be extrapolated for any G-rich DNA sequences. This study also presents a model that can predict the multimerization of G-quadruplexes; the predictions offered by this model are shown to match the results obtained using circular dichroism.