Angular Momentum of a Brane-world Model

In this paper we discuss the properties of the general covariant angular momentum of a five-dimensional brane-world model. Through calculating the total angular momentum of this model, we are able to analyze the properties of the total angular momentum in the inflationary RS model. We show that the space-like components of the total angular momentum of are all zero while the others are non-zero, which agrees with the results from ordinary RS model.Comment: 8 pages; accepted by Chinese Physics

Networked fairness in cake cutting

We introduce a graphical framework for fair division in cake cutting, where comparisons between agents are limited by an underlying network structure. We generalize the classical fairness notions of envy-freeness and proportionality to this graphical setting. Given a simple undirected graph G, an allocation is envy-free on G if no agent envies any of her neighbor's share, and is proportional on G if every agent values her own share no less than the average among her neighbors, with respect to her own measure. These generalizations open new research directions in developing simple and efficient algorithms that can produce fair allocations under specific graph structures. On the algorithmic frontier, we first propose a moving-knife algorithm that outputs an envy-free allocation on trees. The algorithm is significantly simpler than the discrete and bounded envy-free algorithm recently designed in [Aziz and Mackenzie, 2016a] for complete graphs. Next, we give a discrete and bounded algorithm for computing a proportional allocation on descendant graphs, a class of graphs by taking a rooted tree and connecting all its ancestor-descendant pairs

From Ground States to Local Hamiltonians

Traditional quantum physics solves ground states for a given Hamiltonian, while quantum information science asks for the existence and construction of certain Hamiltonians for given ground states. In practical situations, one would be mainly interested in local Hamiltonians with certain interaction patterns, such as nearest neighbour interactions on some type of lattices. A necessary condition for a space $V$ to be the ground-state space of some local Hamiltonian with a given interaction pattern, is that the maximally mixed state supported on $V$ is uniquely determined by its reduced density matrices associated with the given pattern, based on the principle of maximum entropy. However, it is unclear whether this condition is in general also sufficient. We examine the situations for the existence of such a local Hamiltonian to have $V$ satisfying the necessary condition mentioned above as its ground-state space, by linking to faces of the convex body of the local reduced states. We further discuss some methods for constructing the corresponding local Hamiltonians with given interaction patterns, mainly from physical points of view, including constructions related to perturbation methods, local frustration-free Hamiltonians, as well as thermodynamical ensembles.Comment: 11 pages, 2 figures, to be published in PR

Complete Characterization of the Ground Space Structure of Two-Body Frustration-Free Hamiltonians for Qubits

The problem of finding the ground state of a frustration-free Hamiltonian carrying only two-body interactions between qubits is known to be solvable in polynomial time. It is also shown recently that, for any such Hamiltonian, there is always a ground state that is a product of single- or two-qubit states. However, it remains unclear whether the whole ground space is of any succinct structure. Here, we give a complete characterization of the ground space of any two-body frustration-free Hamiltonian of qubits. Namely, it is a span of tree tensor network states of the same tree structure. This characterization allows us to show that the problem of determining the ground state degeneracy is as hard as, but no harder than, its classical analog.Comment: 5pages, 3 figure

Pengaruh Penambahan Gula Pasir Terhadap Kuat Tekan Dan Sifat Kedap Air Mortar

Penggunanan mortar pada pekerjaan dinding rumah, kamar mandi, ataupun bak air saat ini belum maksimal karena banyak dijumpai retak dan tidak kedap air. Dalam mengatasi masalah ini biasa digunakan bahan kimia tambahan (chemical admixtures), tetapi bahan kimia tersebut harganya mahal dan sulit didapat. Penelitian ini bertujuan untuk mengetahui pengaruh penambahan gula pasir terhadap kuat tekan dan sifat kedap air pada mortar. Benda uji yang dipakai untuk pembuatan mortar berbentuk kubus berukuran 5 x 5 x 5 cm dengan variasi penambahan gula pasir 0%, 0,05%, 0,10%, 0,15%, 0,20%, 0,25%, dan 0,30% dari berat semen. Variasi campuran yang dipakai adalah 1PCC : 4Psr, 1PCC : 6Psr, dan 1PCC : 8Psr. Kuat tekan mortar maksimum adalah kuat tekan mortar dengan penambahan gula pasir 0,10 – 0,15% dan menyebabkan kenaikan kuat tekan 18,4% dari kuat tekan mortar normal. Porositas dan absorpsi mortar yang paling kecil adalah mortar dengan tambahan gula pasir 0,10 – 0,15% . Porositas mortar turun 9,99% dari porositas mortar normal dan absorpsi turun 11,84% dari absorpsi mortar normal

The politics of Chinese trade and the Asian financial crises : questioning the wisdom of export-led growth

Between 1987 and 1996 Chinese exports increased by an average of 14% each year. During this decade, export growth became a crucial determinant of overall economic growth. However, as a consequence of the East Asian financial crises, Chinese export growth slowed, threatening the successful implementation of plans to restructure the domestic Chinese economy. This paper traces the reasons for the rapid growth and subsequent slowing of Chinese exports, and asks whether the strategy provides a solid basis for the long term development of the Chinese economy. In particular, the paper focuses on the role and significance of the processing trade in boosting Chinese exports. The high proportion of imported components in processed exports questions whether China is really benefiting as much from export growth as aggregate trade figures seem to suggest

Nodes Effect on the Bending Performance of Laminated Bamboo Lumber Unit

This research studied the ultimate bearing capacity of laminated bamboo lumber (LBL) unit and thereby calculated the maximum bending moment. The load-displacement chart for all specimens was obtained. Then the flexural capacity of members with and without bamboo nodes in the middle section was coMPared. The bending experiment phenomenon of LBL unit was concluded. Different failure modes of bending components were analysed and concluded. Finally, the bending behaviour of LBL units is coMPared with other bamboo and timber products. It is shown that the average ultimate load of BS members is 866.1 N, the average flexural strength is 101 MPa, the average modulus of elasticity is 8.3 GPa, and the average maximum displacement is 17.02 mm. The average ultimate load of BNS members is 1008.1 N, the average flexural strength is 118.02 MPa, the average modulus of elasticity is 9.9 GPa, and the average maximum displacement is 18.26 mm. Laminated bamboo lumber (LBL) unit without bamboo nodes (BNS) has relatively higher flexural strength coMPared with LBL unit with bamboo nodes (BS). The presence of bamboo nodes reduces the strength of the entire structure. Three failure modes were concluded for BS members, and two failure modes were observed for BNS members during the experimental process. According to a coMParison between the LBL unit and other products, the flexural strength and bending modulus of elasticity of the LBL unit are similar as bamboo scrimber and raw bamboo components, which is much higher than timber components

The ontology viewer: facilitating image annotation with ontology terms in the CSIDx imaging database

Computer Systems, Imagery and Medi