Neumann Boundary Conditions from D1-Brane Description at the Presence of Electric Field

We study the fluctuations of D1$\bot$D3 branes from D1-Brane description in the presence of world volume electric field. The fluctuations are found to obey Neumann boundary conditions separating the system into two regions depending on electric field $E$.Comment: 10 pages, v2: some equations are corrected and some points have been clarifie

Praca socjalna i terapia rodziny: interdyscyplinarne korzenie interwencji w rodzinie

Social work practice takes place between persons in families and other social institutions, such as schools, health systems, welfare systems or courts. Drawing from multi-disciplinary theoretical sources, the article brings together social work and family therapy to develop a contemporary model of social work practice with families. There are five generic principles of family systemic practice: 1) persons are inherently relational; 2) families have resilient strengths; 3) family life cycles proceed systemically generating relational tasks for family members; 4) repetitive family interaction generates relational structures; 5) cultures, as perceived by family members, are themselves in dynamic motion, necessitating a transcultural understanding of family interaction.Praktyka pracy socjalnej odbywa się pomiędzy członkami rodzin a innymi instytucjami społecznymi, takimi jak: szkoły, systemy opieki zdrowotnej, systemy opieki społecznej i sądy. Czerpiąc z multidyscyplinarnych źródeł teoretycznych, artykuł łączy pracę socjalną i terapię rodzinną w celu opracowania współczesnego modelu praktyki pracy socjalnej z rodzinami. Istnieje pięć ogólnych zasad systemowej praktyki rodzinnej: 1) osoby są z natury relacyjne; 2) rodziny mają siły rodzące sprężystość psychiczną; 3) cykle życia rodzinnego postępują systemowo, generując relacyjne zadania dla członków rodziny; 4) powtarzające się interakcje rodzinne generują struktury relacyjne; 5) kultury, postrzegane przez członków rodziny, znajdują się w stanie dynamicznego ruchu, co wymaga transkulturowego zrozumienia interakcji rodziny

Electrified Higher-Dimensional Brane Intersections

We discuss the duality of intersecting D1-D5 branes in the low energy effective theory in the presence of electric field. This duality is found to be unbroken. We also deal with the solutions corresponding to two and three excited scalars in the D3-brane theory in the absence and the presence of an electric field. The solutions are given as a spike which is interpreted as an attached bundle of a superposition of coordinates of another brane given as a collective coordinate a long which the brane extends away from the D3-brane. The lowest energy in both cases is higher than the energy found in the case of D1$\bot$D3 branes.Comment: 14 pages, no figures, final version to appear in PL

Subsectors, Dynkin Diagrams and New Generalised Geometries

We examine how generalised geometries can be associated with a labelled Dynkin diagram built around a gravity line. We present a series of new generalised geometries based on the groups $\mathit{Spin}(d,d)\times\mathbb{R}^+$ for which the generalised tangent space transforms in a spinor representation of the group. In low dimensions these all appear in subsectors of maximal supergravity theories. The case $d=8$ provides a geometry for eight-dimensional backgrounds of M theory with only seven-form flux, which have not been included in any previous geometric construction. This geometry is also one of a series of "half-exceptional" geometries, which "geometrise" a six-form gauge field. In the appendix, we consider examples of other algebras appearing in gravitational theories and give a method to derive the Dynkin labels for the "section condition" in general. We argue that generalised geometry can describe restrictions and subsectors of many gravitational theories.Comment: 42 pages, v2: minor improvements and changes, published versio

Virtual Evidence: A Constructive Semantics for Classical Logics

This article presents a computational semantics for classical logic using constructive type theory. Such semantics seems impossible because classical logic allows the Law of Excluded Middle (LEM), not accepted in constructive logic since it does not have computational meaning. However, the apparently oracular powers expressed in the LEM, that for any proposition P either it or its negation, not P, is true can also be explained in terms of constructive evidence that does not refer to "oracles for truth." Types with virtual evidence and the constructive impossibility of negative evidence provide sufficient semantic grounds for classical truth and have a simple computational meaning. This idea is formalized using refinement types, a concept of constructive type theory used since 1984 and explained here. A new axiom creating virtual evidence fully retains the constructive meaning of the logical operators in classical contexts. Key Words: classical logic, constructive logic, intuitionistic logic, propositions-as-types, constructive type theory, refinement types, double negation translation, computational content, virtual evidenc

Electrified Fluctuations in D1⊥\botD3 and D1⊥\botD5 Systems

We present the physical phenomenon of the subject discussed in the paper \cite{fluc}. In that paper we dealt with the fluctuations of funnel solutions of intersecting D1 and D3 branes and the electric field $E$ was considered as very high value causing the results to be non-physical. In the present work, the variation interval of $E$ is to be $[0,\frac{1}{\lambda}[$. Then, we extend the study to discuss the overall transverse fluctuations of electrified funnel solutions of D1$\bot$D5 system in the flat background. The boundary conditions are found to be Neumann boundary conditions.Comment: 19 pages, 6 figure