No Scalar-Haired Cauchy Horizon Theorem in Charged Gauss-Bonnet Black Holes

Recently, a ``no inner (Cauchy) horizon theorem" for static black holes with non-trivial scalar hairs has been proved in Einstein-Maxwell-scalar theories and also in Einstein-Maxwell-Horndeski theories with the non-minimal coupling of a charged (complex) scalar field to Einstein tensor. In this paper, we study an extension of the theorem to the static black holes in Einstein-Maxwell-Gauss-Bonnet-scalar theories, or simply, charged Gauss-Bonnet (GB) black holes. We find that no inner horizon with charged scalar hairs is allowed for the planar (k=0) black holes, as in the case without GB term. On the other hand, for the non-planar (k=+1,-1) black holes, we find that the haired inner horizon can not be excluded due to GB effect generally, though we can not find a simple condition for its existence. As some explicit examples of the theorem, we study numerical GB black hole solutions with charged scalar hairs and Cauchy horizons in asymptotically anti-de Sitter space, and find good agreements with the theorem. As a byproduct, we find a ``no-go theorem" for charged de Sitter GB black holes with charged scalar hairs in arbitrary dimensions.Comment: 21 pages, 8 figure

The Hamiltonian Dynamics of Horava Gravity

We consider the Hamiltonian formulation of Horava gravity in arbitrary dimensions, which has been proposed as a renormalizable gravity model for quantum gravity without the ghost problem. We study the "full" constraint analysis of the "non-projectable" Horava gravity whose potential, V(R), is an arbitrary function of the (intrinsic) Ricci scalar R. We find that there exist generally distinct cases of this theory, depending on (i) whether the Hamiltonian constraint generates new (second-class) constraints (Cases A, C) or just fixes the associated Lagrange multipliers (Case B), or (ii) whether the IR Lorentz-deformation parameter \lambda is at the conformal point (Case C) or not (Cases A, B). It is found that, for Cases A and C, the dynamical degrees of freedom are the same as in general relativity, while, for Case B, there is "one additional phase-space degree of freedom", representing an extra (odd) scalar graviton mode. This would resolve the long-standing debates about the extra graviton modes and achieves the dynamical consistency of the Horava gravity, at the "fully non-linear" level. Several exact solutions are also considered as some explicit examples of the new constraints. The structure of the newly obtained, "extended" constraint algebra seems to be generic to Horava gravity and its general proof would be a challenging problem. Some other challenging problems, which include the path integral quantization and the Dirac bracket quantization are discussed also.Comment: Matches published version, Typos correcte

Symmetries and Conservation Laws in Horava Gravity

Horava gravity has been proposed as a renormalizable quantum gravity without the ghost problem through anisotropic scaling dimensions which break Lorentz symmetry in UV. In the Hamiltonian formalism, due to the Lorentz-violating terms, the constraint structure looks quite different from that of general relativity (GR) but we have recently found that "there exists the case where we can recover the same number of degrees of freedom as in GR", in a rather general set-up. In this paper, we study its Lagrangian perspectives and examine the full diffeomorphism (Diff) symmetry and its associated conservation laws in Horava gravity. Surprisingly, we find that the full Diff symmetry in the action can also be recovered when a certain condition, called "super-condition", which super-selects the Lorentz-symmetric sector in Horava gravity, is satisfied. This indicates that the broken Lorentz symmetry, known as "foliation-preserving" Diff, is just an "apparent" symmetry of the Horava gravity action and rather its "full action symmetry can be as large as the Diff in GR ". The super-condition exactly corresponds to the tertiary constraint in Hamiltonian formalism which is the second-class constraint and provides a non-trivial realization of the Lorentz symmetry otherwise being absent apparently. From the recovered Lorentz symmetry in the action, we obtain the conservation laws with the Noether currents as in covariant theories. The general formula for the conserved Noether charges reproduces the mass of four-dimensional static black holes with an "arbitrary" cosmological constant in Horava gravity, and is independent of ambiguities associated with the choice of asymptotic boundaries. We also discuss several challenging problems, including its implications to Hamiltonian formalism, black hole thermodynamics, radiations from colliding black holes.Comment: 18 pages, no figure

Improvement measures to achieve sustainable construction labor performance

Construction industry is the largest industrial employer of the world. However, construction labor suffers from declining productivity, job satisfaction and wellbeing. Given its volume and labor extensiveness, measures undertaken to improve labor sustainability of the construction industry would have high impact for the future. To improve the sustainability of labor performance, this paper suggests decision-making measures at the strategic, tactical, and operational levels. Data is generated through targeted interviews of the top management of the five biggest Norwegian construction contractors. The measures suggested by the interviewees are analyzed and complemented with theory through a systematic literature review, resulting in the development of 45 measures to achieve sustainable labor performance at strategic, tactical, and operational decision-making levels. Due to strict labor laws and regulations, some frequently reported measures in literature do not hold relevance to the Norwegian construction industry. However, the quality of data and unique position of the Norwegian construction industry magnifies its relevance to the global construction industry

An Internet of Things based framework to enhance just-in-time manufacturing

Just-in-time manufacturing is a main manufacturing strategy used to enhance manufacturers’ competitiveness through inventory and lead time reduction. Implementing just-in-time manufacturing has a number of challenges, for example, effective, frequent and real-time information sharing and communication between different functional departments, responsive action for adjusting the production plan against the continually changing manufacturing situation. Internet of Things technology has the potential to be used for capturing desired data and information from production environment in real time, and the collected data and information can be used for adjusting production schedules corresponding to the changing production environment. This article presents an Internet of Things based framework to support responsive production planning and scheduling in just-in-time manufacturing. The challenges of implementing just-in-time manufacturing are identified first and then an Internet of Things based solution is proposed to address these challenges. A framework to realise the proposed Internet of Things solution is developed and its implementation plan is suggested based on a case study on automotive harness parts manufacturing. This research contributes knowledge to the field of just-in-time manufacturing by incorporating the Internet-of-Things technology to improve the connectivity of production chains and responsive production scheduling capability

The Role of Study Abroad Curricular Interventions in Engineering Students\u27 Intercultural Competence Development

The paper aims to investigate to what degree curricular interventions impact students\u27 global competency development. The interventions examined are those used by program directors to guide students enrolled in a five-year, dual-bachelor degree international engineering program before, during, and after studying and interning abroad. Currently, for ABET accreditation, every engineering program must demonstrate that its graduates possess “the ability to communicate effectively with a range of audiences,” and “the ability to recognize ethical and professional responsibilities in engineering situations and make informed judgments, which must consider the impact of engineering solutions in global, economic, environmental and societal contexts.” [1] According to ABET Executive Director Michael Milligan [2], communication skills, especially the ability to effectively communicate across cultures, are essential to achieve success in the modern workplace. Yet little has been done to define what educational measures are appropriate to accomplish this goal. It is also not clear to what extent global competency is the result of personal attributes, prior experiences, or curricular and extracurricular experiences. Building on previous work [3], [4], [5], [6] we will investigate in what way targeted interventions can impact intercultural competency development in engineering students who spent a year abroad studying & interning in Asia, Europe or Latin America using the language of the country in which they were immersed. The results of a longitudinal study [IRB protocol 1819-164] looking at changes in students’ perceived and developmental orientations along the Intercultural Development Continuum (IDC) and measured by Mitchell Hammer’s internationally validated Intercultural Development Inventory (IDI) instrument [7] will be reported. In addition to the quantitative data from the above study we will analyze qualitative student reflections from assignments given to them while enrolled in a six-credit course taught by their faculty directors during students’ six-month internship abroad. Those consist of written reports, journal entries and video assignments. Another set of qualitative data is derived from post study abroad focus group reflections. Both will be analyzed using standard content analysis procedures to triangulate the data