A novel 90xB0; phase shifter for square waves

In the field of electronic instrumentation there are many applications where a circuit is needed to shift the use of square waves by 90xB0;. In this paper a simple and novel scheme to achieve this end is proposed. This circuit, along with a modulo-two-adder, also enables one to obtain the double frequency component of the original input square wave. It is thus possible to have frequency multiplication by powers of two by cascading such circuits in tandem. The entire circuitry, excepting the time averaging capacitors, can be either13; integrated in one chip or fabricated in tins module form

Ambiguity of Underwater Color Measurement and Color-based Habitat Classification

The paper discusses ambiguities in recording color underwater. Routinely collected RGB imagery can be used for classification and recognition utilizing the proposed probabilistic approach. The device for collection of spectral signatures, necessary for this approach is described

Probabilistic Reconstruction of Color for Species’ Classification Underwater

Color is probably the most informative cue for object recognition and classification in natural scenes. Difference in shades can indicate to the biologist the potential for diversity of species or stress on the habitats. However, severe color distortions may occur in underwater imagery due to wavelength-dependent attenuation of light. Affordable tri-chromatic sensors are used to record the ambient light condition and color correct the imagery, but results show that this approach works reliably only under highly controllable conditions. This paper proposes an approach that combines hyperspectral data collected for the object of interest, hardware properties of the imaging sensor, and exterior conditions (optical properties of water and illumination) with tri-chromatic underwater imagery. Due to ambiguity of color reconstruction underwater, demonstrated in the paper, a probabilistic approach is used for classification that allows the identification of the object of interest from other objects

Sufficient Conditions for Tuza's Conjecture on Packing and Covering Triangles

Given a simple graph $G=(V,E)$, a subset of $E$ is called a triangle cover if it intersects each triangle of $G$. Let $\nu_t(G)$ and $\tau_t(G)$ denote the maximum number of pairwise edge-disjoint triangles in $G$ and the minimum cardinality of a triangle cover of $G$, respectively. Tuza conjectured in 1981 that $\tau_t(G)/\nu_t(G)\le2$ holds for every graph $G$. In this paper, using a hypergraph approach, we design polynomial-time combinatorial algorithms for finding small triangle covers. These algorithms imply new sufficient conditions for Tuza's conjecture on covering and packing triangles. More precisely, suppose that the set $\mathscr T_G$ of triangles covers all edges in $G$. We show that a triangle cover of $G$ with cardinality at most $2\nu_t(G)$ can be found in polynomial time if one of the following conditions is satisfied: (i) $\nu_t(G)/|\mathscr T_G|\ge\frac13$, (ii) $\nu_t(G)/|E|\ge\frac14$, (iii) $|E|/|\mathscr T_G|\ge2$. Keywords: Triangle cover, Triangle packing, Linear 3-uniform hypergraphs, Combinatorial algorithm

Palaeoenvironmental signatures revealed from rare earth element (REE) compositions of vertebrate microremains of the Vesiku Bone Bed (Homerian, Wenlock), Saaremaa Island, Estonia

The Estonian Journal of Earth Sciences is an open access journal and applies the Creative Commons Attribution 4.0 International License CC BY to all its papers (http://creativecommons.org/licenses/by/4.0/). The attached file is the published version of the article

Lymphatic Filariasis Control in Tanzania: Effect of Six Rounds of Mass Drug Administration with Ivermectin and Albendazole on Infection and Transmission.

Control of lymphatic filariasis (LF) in most countries of sub-Saharan Africa is based on annual mass drug administration (MDA) with a combination of ivermectin and albendazole, in order to interrupt transmission. We present findings from a detailed study on the effect of six rounds of MDA with this drug combination as implemented by the National Lymphatic Filariasis Elimination Programme (NLFEP) in a highly endemic rural area of north-eastern Tanzania.\ud The effect of treatment on transmission and human infection was monitored in a community- and a school-based study during an 8-year period (one pre-intervention and 7 post-intervention years) from 2003 to 2011. Before intervention, 24.5% of the community population had microfilariae (mf) in the blood, 53.3% had circulating filarial antigens (CFA) and 78.9% had specific antibodies to the recombinant filarial antigen Bm14. One year after the sixth MDA, these values had decreased considerably to 2.7%, 19.6% and 27.5%, respectively. During the same period, the CFA prevalence among new intakes of Standard 1 pupils in 10 primary schools decreased from 25.2% to 5.6%. In line with this, transmission by the three vectors (Anopheles gambiae, An. funestus and Culex quinquefasciatus) as determined by dissection declined sharply (overall vector infectivity rate by 99.3% and mean monthly transmission potential by 99.2% between pre-intervention and fifth post-intervention period). A major shift in vector species composition, from predominantly anopheline to almost exclusively culicine was observed over the years. This may be largely unrelated to the MDAs but may have important implications for the epidemiology of LF in the area. Six MDAs caused considerable decrease in all the measured indices for transmission and human infection. In spite of this, indices were still relatively high in the late period of the study, and it may take a long time to reach the recommended cut-off levels for interruption of transmission unless extra efforts are made. These should include increased engagement of the target population in the control activities, to ensure higher treatment coverage. It is expected that the recent initiative to distribute insecticide impregnated bed nets to every household in the area will also contribute towards reaching the goal of successful LF elimination

New Approaches for Evaluating Lidar-Derived Shoreline

This study presents and compares two new methods of assessing the uncertainty of lidar-derived National Shoreline mapped by NOAA’s National Geodetic Survey: an empirical (ground-based) approach and a stochastic (Monte Carlo) approach. OCIS codes: (280.3640) Lidar; (120.2830) Height measurements; (000.4430) Numerical approximation and analysi

Comprensi?n del concepto de educaci?n ambiental de tres profesores de b?sica secundaria de la intituci?n educativa San Sim?n del municipio de Ibagu?, basado en el an?lisis de concepciones de ambiente y pr?ctica de aula

34 p. Recurso Electr?nicoEste proyecto investigativo tiene como objetivo general comprender el concepto de educaci?n ambiental (EA), analizando las diferentes concepciones entorno al ambiente y sus pr?cticas de aula de tres profesores de la Instituci?n Educativa San Isidro de la ciudad de Ibagu?, sin importar si son acertadas, erradas, si obedecen a corrientes de pensamiento ambiental, si se fundamentan de manera acad?mica o por experiencia y sensibilidad hacia el tema. Los profesores fueron escogidos de manera aleatoria, d?ndole importancia a su ?rea del conocimiento m?s no a su asertividad a la hora de tratar tema relacionados con el ambiente o EA. Coincidencialmente los profesores resultantes, orientan ?reas del conocimiento muy dis?miles entre s? (Ciencias Naturales, Sociales, e Ingl?s). Se suministr? un instrumento encuesta de cinco preguntas abiertas, las respuestas se analizaron y dieron como resultado conceptos y concepciones, marcadas por el ?rea del conocimiento de cada profesor pero todos le dan un papel protag?nico a la EA y esperanzador y la consideran c?mo el ?nico medio para lograr generar conciencia entre la humanidad, para cambiar los h?bitos de consumo que perjudican el planeta tierra, aduciendo que los problemas que est?n deteriorando a la naturaleza afectan a todos sin importar raza, religi?n o credo, pero desconocen que para lograr esta relevancia en la EA es necesario que esta cuente con un fuerte rigor acad?mico.This research project has the overall objective of understanding the concept of environmental education (EA), analyzing the different conceptions around the room and classroom practices of three teachers of School San Isidro city of Ibague, regardless if they are successful, wrong, if they obey current environmental thinking, if substantiated academically or through experience and sensitivity to the issue. Teachers were chosen at random, giving importance to their area of knowledge but not his assertiveness in addressing environment-related topic or EA. Coincidentally, the resulting teachers, guide very different areas of knowledge together (science, social, and English). One survey instrument was supplied five open questions, the answers were analyzed and led to concepts and conceptions result, marked by the area of knowledge of each teacher but all give a central role to the EA and hopeful and consider it as the only means to achieve raise awareness among mankind, to change the habits that harm the planet earth, arguing that the problems that are damaging to nature affect all regardless of race, religion or creed, but know that to achieve this relevance in EA is necessary for it to have a strong academic rigor. Keywords: Environmental Education, Education, Conceptions, classroom practices