Approximation Algorithms for Route Planning with Nonlinear Objectives

We consider optimal route planning when the objective function is a general nonlinear and non-monotonic function. Such an objective models user behavior more accurately, for example, when a user is risk-averse, or the utility function needs to capture a penalty for early arrival. It is known that as nonlinearity arises, the problem becomes NP-hard and little is known about computing optimal solutions when in addition there is no monotonicity guarantee. We show that an approximately optimal non-simple path can be efficiently computed under some natural constraints. In particular, we provide a fully polynomial approximation scheme under hop constraints. Our approximation algorithm can extend to run in pseudo-polynomial time under a more general linear constraint that sometimes is useful. As a by-product, we show that our algorithm can be applied to the problem of finding a path that is most likely to be on time for a given deadline.Comment: 9 pages, 2 figures, main part of this paper is to be appear in AAAI'1

Mano de la Amistad: a Thin Shell Concrete Structure Designed for the People of Havana, Cuba

In designing a thin shell structure to cover the performance space on Tribuna Anti Imperialista Jose Marti, in Havana, Cuba, we developed a heavily symbolic concept and further abstracted it to reach our design. Basing the concept on the quote to the right by Obama about US and Cuba relations, we wanted our design to be representative of a hand that works to adjoin the plaza to the US Embassy which is directly west of the site. The “wrist” portion adds an asymmetric element, while the fingers provide a backdrop to the performers as well as a view through to the US Embassy and Cuban flag monument behind the space. The layering of two shell structures helps to abstract the hand like form, particularly in planview, and reinforces the symbolic aspect of the two countries coming together. Interest is also added via an oculus in the bottom structure that depending on the viewer’s angle, provides images of the sky, upper shell, or both simultaneously

A Submodular Approach for Electricity Distribution Network Reconfiguration

Distribution network reconfiguration (DNR) is a tool used by operators to balance line load flows and mitigate losses. As distributed generation and flexible load adoption increases, the impact of DNR on the security, efficiency, and reliability of the grid will increase as well. Today, heuristic-based actions like branch exchange are routinely taken, with no theoretical guarantee of their optimality. This paper considers loss minimization via DNR, which changes the on/off status of switches in the network. The goal is to ensure a radial final configuration (called a spanning tree in the algorithms literature) that spans all network buses and connects them to the substation (called the root of the tree) through a single path. We prove that the associated combinatorial optimization problem is strongly NP-hard and thus likely cannot be solved efficiently. We formulate the loss minimization problem as a supermodular function minimization under a single matroid basis constraint, and use existing algorithms to propose a polynomial time local search algorithm for the DNR problem at hand and derive performance bounds. We show that our algorithm is equivalent to the extensively used branch exchange algorithm, for which, to the best of our knowledge, we pioneer in proposing a theoretical performance bound. Finally, we use a 33-bus network to compare our algorithm\u27s performance to several algorithms published in the literature

Performance model for “Just-in-Time” problems in real-time multimedia applications

Over the last few years, the use of large-scale multimedia data applications has been growing tremendously, and this growth is not likely to slow down in the near future. Many multimedia applications operate in a real-time environment (e.g., surveillance cameras, iris scans), which must meet strict time constraints, i.e. to analyze video frames at the same rate as a camera produces them. To meet this requirement, Grid computing is rapidly becoming indispensable. However, the variabilities of the software and the hardware in grid environment cause the strong burstiness in the transmission delay of video frames. Because the burstiness is unknown beforehand, it is difficult to determine the right sending moments of video frames. If the time interval between sending two sequential frames is too large, then the service utilization may be low. If use large buffer to guarantee the service utilization, then video frames may be outof- date because of the long waiting time at buffer in the server side. This problem is referred to as “Just-in-time” problem. To solve this problem, it is essential to determine the right sending moments of video frames, properly dealing with the trade-off between the service utilization and the “up-to-date” of video frames. Motivated by this, in this paper we develop an adaptive control method that react to the continuously changing circumstances in grid system so as to obtain the highest service utilization on the one hand and to keep the video frame up-to-date on the other hand. Extensive experimental validation in our DAS-3 testbed and the trace-driven simulation show that our method is indeed highly effective

Simulation games as tools for integrative dynamic learning: The case of the management course at the University of Algarve

Today, in order to people or organizations survive in a changing environment it is essential to adapt. Learning provided to people is a key feature for an active response since it implies acquiring knowledge, skills and competencies to cope successfully with different circumstances. Literature has focused on how digital games support education because simulators represent dynamic models of real situations; so, their goal is to ensure that the player denotes his decisions consequences. When teaching certain skills through these games, a reflection stage is crucial to evaluate the experiences gathered during the simulation and promote knowledge appliance by participants into the real world. Due to its multiple scientific contributions, gaming can overlap a valid solution to prepare learners understanding regarding complex contexts. This research denotes an ongoing PhD research about the characteristics of a management course unit (at the University of Algarve, Portugal) that explores a business simulator- Cesim Global Challenge- for learning purposes, as well as the effectiveness of an integrative approach (new learning environments) on students’ engagement and dynamic learning outcomes. From the earlier empirical data is understandable game-based learning advantages and disadvantages within Management and Entrepreneurship courses

The nucleolar protein NIFK promotes cancer progression via CK1α/β-catenin in metastasis and Ki-67-dependent cell proliferation.

Nucleolar protein interacting with the FHA domain of pKi-67 (NIFK) is a Ki-67-interacting protein. However, its precise function in cancer remains largely uninvestigated. Here we show the clinical significance and metastatic mechanism of NIFK in lung cancer. NIFK expression is clinically associated with poor prognosis and metastasis. Furthermore, NIFK enhances Ki-67-dependent proliferation, and promotes migration, invasion in vitro and metastasis in vivo via downregulation of casein kinase 1α (CK1α), a suppressor of pro-metastatic TCF4/β-catenin signaling. Inversely, CK1α is upregulated upon NIFK knockdown. The silencing of CK1α expression in NIFK-silenced cells restores TCF4/β-catenin transcriptional activity, cell migration, and metastasis. Furthermore, RUNX1 is identified as a transcription factor of CSNK1A1 (CK1α) that is negatively regulated by NIFK. Our results demonstrate the prognostic value of NIFK, and suggest that NIFK is required for lung cancer progression via the RUNX1-dependent CK1α repression, which activates TCF4/β-catenin signaling in metastasis and the Ki-67-dependent regulation in cell proliferation

Sacral Nerve Stimulation for Treatment of Chronic Intractable Anorectal Pain -A Case Report-

Despite recent methodological advancement of the practical pain medicine, many cases of the chronic anorectal pain have been intractable. A 54-year-old female patient who had a month history of a constant severe anorectal pain was referred to our clinic for further management. No organic or functional pathology was found. In spite of several modalities of management, such as medications and nerve blocks had been applied, the efficacy of such treatments was not long-lasting. Eventually, she underwent temporary then subsequent permanent sacral nerve stimulation. Her sequential numerical rating scale for pain and pain disability index were markedly improved. We report a successful management of the chronic intractable anorectal pain via permanent sacral nerve stimulation. But further controlled studies may be needed

Orthogonalities and functional equations

In this survey we show how various notions of orthogonality appear in the theory of functional equations. After introducing some orthogonality relations, we give examples of functional equations postulated for orthogonal vectors only. We show their solutions as well as some applications. Then we discuss the problem of stability of some of them considering various aspects of the problem. In the sequel, we mention the orthogonality equation and the problem of preserving orthogonality. Last, but not least, in addition to presenting results, we state some open problems concerning these topics. Taking into account the big amount of results concerning functional equations postulated for orthogonal vectors which have appeared in the literature during the last decades, we restrict ourselves to the most classical equations