Gravitational shock waves and vacuum fluctuations

We show that the vacuum expectation value of the stress-energy tensor of a scalar particle on the background of a spherical gravitational shock wave does not give a finite expression in second order perturbation theory, contrary to the case seen for the impulsive wave. No infrared divergences appear at this order. This result shows that there is a qualitative difference between the shock and impulsive wave solutions which is not exhibited in first order.Comment: Submitted to Class. and Quant. Grav.,7 pages, no figure

Duality invariance of non-anticommutative N=1/2 supersymmetric U(1) gauge theory

A parent action is introduced to formulate (S-) dual of non-anticommutative N=1\2 supersymmetric U(1) gauge theory. Partition function for parent action in phase space is utilized to establish the equivalence of partition functions of the theories which this parent action produces. Thus, duality invariance of non-anticommutative N=1\2 supersymmetric U(1) gauge theory follows. The results which we obtained are valid at tree level or equivalently at the first order in the nonanticommutativity parameter C_{\mu\nu}.Comment: 12 pages, some comments and references are added. To appear in JHE

N=1/2 Supersymmetric gauge theory in noncommutative space

A formulation of (non-anticommutative) N=1/2 supersymmetric U(N) gauge theory in noncommutative space is studied. We show that at one loop UV/IR mixing occurs. A generalization of Seiberg-Witten map to noncommutative and non-anticommutative superspace is employed to obtain an action in terms of commuting fields at first order in the noncommutativity parameter tetha. This leads to abelian and non-abelian gauge theories whose supersymmetry transformations are local and non-local, respectively.Comment: One reference added, published versio

N=2 SYM Action as a BRST Exact Term, Topological Yang Mills and Instantons

By constructing a nilpotent extended BRST operator \bs that involves the N=2 global supersymmetry transformations of one chirality, we show that the standard N=2 off-shell Super Yang Mills Action can be represented as an exact BRST term \bs \Psi, if the gauge fermion $\Psi$ is allowed to depend on the inverse powers of supersymmetry ghosts. By using this nonanalytical structure of the gauge fermion (via inverse powers of supersymmetry ghosts), we give field redefinitions in terms of composite fields of supersymmetry ghosts and N=2 fields and we show that Witten's topological Yang Mills theory can be obtained from the ordinary Euclidean N=2 Super Yang Mills theory directly by using such field redefinitions. In other words, TYM theory is obtained as a change of variables (without twisting). As a consequence it is found that physical and topological interpretations of N=2 SYM are intertwined together due to the requirement of analyticity of global SUSY ghosts. Moreover, when after an instanton inspired truncation of the model is used, we show that the given field redefinitions yield the Baulieu-Singer formulation of Topological Yang Mills.Comment: Latex, 1+15 pages. Published versio

Designing difficult office space allocation problem instances with mathematical programming

Office space allocation (OSA) refers to the assignment of room space to a set of entities (people, machines, roles, etc.), with the goal of optimising the space utilisation while satisfying a set of additional constraints. In this paper, a mathematical programming approach is developed to model and generate test instances for this difficult and important combinatorial optimisation problem. Systematic experimentation is then carried out to study the difficulty of the generated test instances when the parameters for adjusting space misuse (overuse and underuse) and constraint violations are subject to variation. The results show that the difficulty of solving OSA problem instances can be greatly affected by the value of these parameters

EELISA Credential: The Recognition Of Commitment And Impact In The Addressing Of Societal Challenges In The EELISA Alliance

EELISA Credential is a unique recognition process provided to EELISA students, professional and alumni who are part of the mission-driven EELISA communities and reflects the commitment and impact level achieved in the addressing of a societal challenge. The EELISA Credential is an individual, progressive environment on which students collect badges. These badges are acquired after verifying the achievement of an educational outcome level after participating in community\u27s educational activities. A badge represents the unit of learning acquisition and impact that corresponds to an educational outcome. It is reflected in the EELISA Credential which itself refers to an impact level and a Sustainable Development Goal (SDG). The impact level represents the badge measurement scale. In the EELISA Credential, there are 5 levels of impact (discovery, knowledge, engagement, action, transformation) that correspond to learning objectives relative to SDGs. The education activities proposed by EELISA Communities are defined around a societal challenge defined by a problem owner (faculty, students, local communities). Each activity is centered in 1 or 2 SDGs, and recognizes a maximum of 4 badges. Through the involvement in the activities of EELISA Communities, students enrich their EELISA Credential in areas addressing Sustainable Developments Goals (SDGs), progressively improving their capacity for understanding, action and transformation. In this practice paper, we will present the requirements for activities to be part of the EELISA Credential, representative and successful activities, the Quality Assurance system, the lessons learnt in the process of implementing the credential and how EELISA Credential will evolve in the future

Sense and Antisense Transcripts of Convergent Gene Pairs in Arabidopsis thaliana Can Share a Common Polyadenylation Region

The Arabidopsis genome contains a large number of gene pairs that encode sense and antisense transcripts with overlapping 3′ regions, indicative for a potential role of natural antisense transcription in regulating sense gene expression or transcript processing. When we mapped poly(A) transcripts of three plant gene pairs with long overlapping antisense transcripts, we identified an unusual transcript composition for two of the three gene pairs. Both genes pairs encoded a class of long sense transcripts and a class of short sense transcripts that terminate within the same polyadenylation region as the antisense transcripts encoded by the opposite strand. We find that the presence of the short sense transcript was not dependent on the expression of an antisense transcript. This argues against the assumption that the common termination region for sense and antisense poly(A) transcripts is the result of antisense-specific regulation. We speculate that for some genes evolution may have especially favoured alternative polyadenylation events that shorten transcript length for gene pairs with overlapping sense/antisense transcription, if this reduces the likelihood for dsRNA formation and transcript degradation