BTZ Solutions on Codimension-2 Braneworlds

We consider five-dimensional gravity with a Gauss-Bonnet term in the bulk and an induced gravity term on a 2-brane of codimension-2. We show that this system admits BTZ-like black holes on the 2-brane which are extended into the bulk with regular horizons.Comment: 6 pages. Talk given at Recent Developments in Gravity (NEB XIII), Thessaloniki, Greece, June 4-6, 2008

Exploring Problem Based Learning to Promote 21st Century Learning Skills in Full Day Kindergarten

The kindergarten program at the study site transitioned from half day to full day, yet the curriculum was not updated to accommodate the full day schedule, or to include best practices. In order to prepare learners for their future in education, activities were implemented to determine how problem based learning can promote acquisition of the 21st century learning skills. The purpose of this qualitative study was to create and implement an effective, full day curriculum that promotes 21st century learning skills for kindergarten students. This project, rooted in constructivism which allows for active and social learning, supplements the existing half day curriculum and encourages collaborating, experiential learning, and problem solving. The question that guided this project study involved understanding how 21st century learning skills of collaboration, problem solving, effective communication, and decision making can be integrated into a full day kindergarten curriculum. A qualitative participatory action research framework was used to gather data in the form of field notes during observations and interviews were coded and analyzed to find themes and categories that emerged. The findings revealed that 21st century skills can be acquired by kindergarten learners when the role of the teacher changes into a facilitator and models appropriate behaviors and skills. The final project includes a teacher\u27s guide to support teachers as they transition into a new role as a facilitator as well as sample lessons with suggestions and hints for implementation. This project contributes to social change by presenting teachers with a data driven curriculum that offers an authentic, experiential way of teaching to help students develop skills necessary to become successful members of their classroom

The relationship between Higher Education and labour market in Greece : the weakest link?

The high level of graduate unemployment, even though it is acknowledged as one of the most distinctive characteristics of the Greek labour market, it has not attracted enough attention in the academic literature. This paper utilizes micro-data from the Labour Force Survey in order to investigate how the employment situation of young (aged 35 and below) graduates varies across fields of study. The findings suggest that graduates of disciplines that have high levels of private sector employment, such as Polytechnics and Computer Science, are in general better off in the Greek labour market. On the other hand, graduates of disciplines that are traditionally related to the needs of the public sector, such as Sociology and Humanities, face poor employment prospects. The findings of this study highlight the need for drastic reforms of the Higher Education system

Novel fuzzy-based optimization approaches for the prediction of ultimate axial load of circular concrete-filled steel tubes

An accurate estimation of the axial compression capacity of the concrete-filled steel tubular (CFST) column is crucial for ensuring the safety of structures containing them and preventing related failures. In this article, two novel hybrid fuzzy systems (FS) were used to create a new framework for estimating the axial compression capacity of circular CCFST columns. In the hybrid models, differential evolution (DE) and firefly algorithm (FFA) techniques are employed in order to obtain the optimal membership functions of the base FS model. To train the models with the new hybrid techniques, i.e., FS-DE and FS-FFA, a substantial library of 410 experimental tests was compiled from openly available literature sources. The new model\u2019s robustness and accuracy was assessed using a variety of statistical criteria both for model development and for model validation. The novel FS-FFA and FS-DE models were able to improve the prediction capacity of the base model by 9.68% and 6.58%, respectively. Furthermore, the proposed models exhibited considerably improved performance compared to existing design code methodologies. These models can be utilized for solving similar problems in structural engineering and concrete technology with an enhanced level of accuracy

Persistent left superior vena cava mistaken for nodal metastasis: a case report

<p>Abstract</p> <p>Introduction</p> <p>Evaluation of the mediastinum is crucial for patients with lung cancer. Mediastinal lymph node metastases play a dramatic role in the process of staging. Physicians should be aware of the potential pitfalls regarding mediastinal evaluation. This case report provides an example.</p> <p>Case presentation</p> <p>We report the case of a 57-year-old Caucasian man who presented with a four-month history of non-productive cough. He was diagnosed with non-small cell lung cancer. Initially, it was thought to be inoperable due to the presence of a para-aortic lymph node. A more careful examination of the mediastinum revealed that the "lymph node" was in fact a persistent left superior vena cava.</p> <p>Conclusions</p> <p>This study highlights the difficulties in mediastinal staging, especially when intravenous contrast is not used. The recognition of this vascular malformation dramatically changed the therapeutic decisions, giving our patient the opportunity of surgical resection. To the best of our knowledge, such correlation has not been described in English literature.</p

Immunotherapy of Cancer: Developments and Reference Points, an Unorthodox Approach.

Oncology is currently a sector of medical science with accelerated progress due to rapid technological development, the advancement in molecular biology, and the invention of many innovative therapies. Immunotherapy partially accounts for this advance, since it is increasingly playing an important role in the treatment of cancer patients, bringing on a sense of hope and optimism through a series of clinical studies and cases with spectacular results. Immunotherapy, after the initial successes it experienced in the early 20th century, was forgotten after chemotherapy and radiotherapy prevailed and developed slowly in the background. Today, it is the new hope for cancer treatment, despite the unorthodox path it has followed. In this article, we study the course and key points of the discovery of immune-oncology from the oncologist's point of view. We also record the questions that have been posed about immunotherapy that sometimes lead to confusion or stalemate

Authentication with Weaker Trust Assumptions for Voting Systems

Some voting systems are reliant on external authentication services. Others use cryptography to implement their own. We combine digital signatures and non-interactive proofs to derive a generic construction for voting systems with their own authentication mechanisms, from systems that rely on external authentication services. We prove that our construction produces systems satisfying ballot secrecy and election verifiability, assuming the underlying voting system does. Moreover, we observe that works based on similar ideas provide neither ballot secrecy nor election verifiability. Finally, we demonstrate applicability of our results by applying our construction to the Helios voting system

Instability of brane cosmological solutions with flux compactifications

We discuss the stability of the higher-dimensional de Sitter (dS) brane solutions with two-dimensional internal space in the Einstein-Maxwel theory. We show that an instability appears in the scalar-type perturbations with respect to the dS spacetime. We derive a differential relation which has the very similar structure to the ordinary laws of thermodynamics as an extension of the work for the six-dimensional model [20]. In this relation, the area of dS horizon (integrated over the two internal dimensions) exactly behaves as the thermodynamical entropy. The dynamically unstable solutions are in the thermodynamically unstable branch. An unstable dS compactification either evolves toward a stable configuration or two-dimensional internal space is decompactified. These dS brane solutions are equivalent to the accelerating cosmological solutions in the six-dimensional Einstein-Maxwell-dilaton theory via dimensional reduction. Thus, if the seed higher-dimensional solution is unstable, the corresponding six-dimensional solution is also unstable. From the effective four-dimensional point of view, a cosmological evolution from an unstable cosmological solution in higher dimensions may be seen as a process of the transition from the initial cosmological inflation to the current dark energy dominated Universe.Comment: 11 pages, 3 figures, references added, to appear in CQ

Perturbations of Gauss-Bonnet Black Strings in Codimension-2 Braneworlds

We derive the Lichnerowicz equation in the presence of the Gauss-Bonnet term. Using the modified Lichnerowicz equation we study the metric perturbations of Gauss-Bonnet black strings in Codimension-2 Braneworlds.Comment: 26 pages, no figures, clarifying comments and one reference added, to be published in JHE