124 research outputs found

    Constraint algorithm for k-presymplectic Hamiltonian systems. Application to singular field theories

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    The k-symplectic formulation of field theories is especially simple, since only tangent and cotangent bundles are needed in its description. Its defining elements show a close relationship with those in the symplectic formulation of mechanics. It will be shown that this relationship also stands in the presymplectic case. In a natural way, one can mimick the presymplectic constraint algorithm to obtain a constraint algorithm that can be applied to kk-presymplectic field theory, and more particularly to the Lagrangian and Hamiltonian formulations of field theories defined by a singular Lagrangian, as well as to the unified Lagrangian-Hamiltonian formalism (Skinner--Rusk formalism) for k-presymplectic field theory. Two examples of application of the algorithm are also analyzed.Comment: 22 p

    Pre-multisymplectic constraint algorithm for field theories

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    We present a geometric algorithm for obtaining consistent solutions to systems of partial differential equations, mainly arising from singular covariant first-order classical field theories. This algorithm gives an intrinsic description of all the constraint submanifolds. The field equations are stated geometrically, either representing their solutions by integrable connections or, what is equivalent, by certain kinds of integrable m-vector fields. First, we consider the problem of finding connections or multivector fields solutions to the field equations in a general framework: a pre-multisymplectic fibre bundle (which will be identified with the first-order jet bundle and the multimomentum bundle when Lagrangian and Hamiltonian field theories are considered). Then, the problem is stated and solved in a linear context, and a pointwise application of the results leads to the algorithm for the general case. In a second step, the integrability of the solutions is also studied. Finally, the method is applied to Lagrangian and Hamiltonian field theories and, for the former, the problem of finding holonomic solutions is also analized.Comment: 30 pp. Presented in the International Workshop on Geometric Methods in Modern Physics (Firenze, April 2005

    PERCEPTIONS DES FEMMES ACCOUCHEES SUR L’ACCOUCHEMENT A DOMICILE DANS LA VILLE DE LUBUMBASHI: Cas de la Commune de Kampemba, Quartier Bongonga 2021

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    CONTEXT  Home births remain a global concern. Despite efforts to ban them, they are frequent and continue to claim many victims (3) the objectives of this study are to describe the socio-demographic profile, assess their knowledge of the risks, their perceptions, and determine the factors favoring home births in the Bongonga district. METHOD:  A qualitative study of phenomenological approach was  made for a period of one month on a population made up of women who gave birth at home. The data collection makes semi-structured interviews from an interview guide; data entered and encoded on Word, the analysis is the subject of an audition and transcription in theme. Then proceed to group the units of significance. By confronting similarities and contradictions, in order to identify free and imaginary variation and then achieve triangulation. RESULTS On 13 interview of women the result shows that the age of the women interviewed was 30 years old varying up to 43 years old. 6 out of 13 had given birth once at home; 4 out of 13 had given birth twice; 3 out of 13 had given birth 3 times at home. Their socio-demographic profile shows that 11 out of 13 were married, the major factors being the lack of money, occupation and the negligence of the care providers. CONCLUSION: The results of the qualitative study of phenomenological approach on home births is a real problem and women need help. However, they have a negative perception and remain optimistic about the resolution of the problem. Reproductive authorities needed to find lasting solutions to this situation.  CONTEXT  Home births remain a global concern. Despite efforts to ban them, they are frequent and continue to claim many victims (3) the objectives of this study are to describe the socio-demographic profile, assess their knowledge of the risks, their perceptions, and determine the factors favoring home births in the Bongonga district. METHOD:  A qualitative study of phenomenological approach was  made for a period of one month on a population made up of women who gave birth at home. The data collection makes semi-structured interviews from an interview guide; data entered and encoded on Word, the analysis is the subject of an audition and transcription in theme. Then proceed to group the units of significance. By confronting similarities and contradictions, in order to identify free and imaginary variation and then achieve triangulation. RESULTS On 13 interview of women the result shows that the age of the women interviewed was 30 years old varying up to 43 years old. 6 out of 13 had given birth once at home; 4 out of 13 had given birth twice; 3 out of 13 had given birth 3 times at home. Their socio-demographic profile shows that 11 out of 13 were married, the major factors being the lack of money, occupation and the negligence of the care providers. CONCLUSION: The results of the qualitative study of phenomenological approach on home births is a real problem and women need help. However, they have a negative perception and remain optimistic about the resolution of the problem. Reproductive authorities needed to find lasting solutions to this situation. &nbsp

    Lead Speciation in the Dusts Emitted from Non-Ferrous Metallurgy Processes

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    The paper presents results for the speciation analysis of lead in dusts derived from dedusting of technological gasses from metallurgical processes of non-ferrous metals with different elementary content, made in accordance with two equal sequential extractions. Analytical procedure A provided possibilities for determination of fraction of Pb2+, metallic lead and fraction containing mainly lead sulfides. The second procedure (procedure B) was sequential extraction in accordance with Tessier. The results obtained in accordance with procedure A indicate that, regardless of the dust origin, the dominant group of Pb compounds is composed of lead salts which are soluble under alkaline conditions or lead compounds that form plumbites in the reaction with NaOH

    Mathematical models for immunology:current state of the art and future research directions

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    The advances in genetics and biochemistry that have taken place over the last 10 years led to significant advances in experimental and clinical immunology. In turn, this has led to the development of new mathematical models to investigate qualitatively and quantitatively various open questions in immunology. In this study we present a review of some research areas in mathematical immunology that evolved over the last 10 years. To this end, we take a step-by-step approach in discussing a range of models derived to study the dynamics of both the innate and immune responses at the molecular, cellular and tissue scales. To emphasise the use of mathematics in modelling in this area, we also review some of the mathematical tools used to investigate these models. Finally, we discuss some future trends in both experimental immunology and mathematical immunology for the upcoming years

    Formy żelaza i pierwiastków śladowych w silnie kwaśnych glebach bielicowych Gór Izerskich

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    Forms of Fe, Pb, Zn and Cu were determined by the means of sequential extraction in podzol profiles developed from granitogneiss in the Izerskie Mountains. Seven metal fractions were separated. Organic matter supply to soil profile was found to be a crucial factor determining the total concentration of lead in soil horizons. The main forms of copper and zinc were the ones occluded in Fe oxides and their total concentration increased with the depth within the soils profiles, which proved the considerable mobility of these elements. The results obtained from the study show that the total amount of trace elements in soil genetic horizons depends on the weathering process of primary and secondary soil minerals, organic matter input as well as the airborne contaminants, and their distribution in soil profile is modified by strongly acidic soil reaction

    Total Contents and soluble forms of trace elements in serpentinite wastes of the Naslawice quarry

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    W trakcie mielenia skał serpentynitowych w celu uzyskania kruszywa o odpowiedniej granulacji powstają znaczne ilości drobnoziarnistych odpadów, zwałowanych w sąsiedztwie kamieniołomu i zakładu przeróbczego. Materiał zwałowany ma z reguły charakter utworu gliniasto lub piaszczysto-szkieletowego, o wysokim pH oraz bardzo niskiej zawartości przyswajalnego fosforu i potasu, a bardzo wysokiej magnezu. Całkowita zawartość Pb, Zn i Cu jest zbliżona do występującej w glebach wytworzonych z różnych skał macierzystych. Chrom występuje w ilości od 415 do 760 mg·kg⁻¹, natomiast nikiel nawet do 4100 mg·kg⁻¹, tj. w koncentracjach znacznie przewyższających normalnie występujące w glebach. Pojedyncza ekstrakcja z użyciem 0,1 mol(HCl) uwalniała 7,5-22 mg Cr·kg⁻¹ oraz 60-307 mg Ni·kg⁻¹, tj. odpowiednio do 5 i do 7,5% całkowitej zawartości tych pierwiastków. Ekstrakcja z użyciem 1 mol(NH₄NO₃)·dm⁻³ uwalniała do 2 mg Cr·kg⁻¹ i do 10,2 mg Ni·kg⁻¹ tj. odpowiednio do 0,34% i do 1,9% całkowitej zawartości Cr oraz Ni. Wydaje się, że znaczne ilości ekstrahowanych form rozpuszczalnych chromu oraz niklu, mimo niewielkiego ich udziału w całkowitej zawartości tych pierwiastków, mogą niekorzystnie (lub nawet toksycznie) oddziaływać na roślinność wprowadzaną na zwałowiska w trakcie ich rekultywacji.Large amounts of rock wastes produced during milling of the alkaline serpentinite rock are stored in piles formed closely to the quarry. In present study, the total content and soluble forms of selected heavy metals were analysed in the context of soil reclamation on waste piles in the Nasławice quarry. Strongly gravely, loamy or sandy material showed high pH value and soluble magnesium content, while very low contents of soluble potassium and phosphorus. Total contents of Pb, Zn and Cu were similar to the amount occurring in other rocks and are typical for „normal” soils in Poland. Cr and Ni contents were at least 100 fold higher than in unpolluted agricultural soils in Poland. Single extractions of soluble Ni and Cr release relatively high amounts of these metals, what may be harmful or toxic for plants
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