Information asymmetry, trading volume and returns in the Malaysian stock market

This paper examines investors’ motive to trade on the Malaysian stock market from 1st July 1997 to 30th June 2005. By applying ordinary least square (OLS) to 272 stocks as well as in three size groups, both the time series and cross-sectional results indicate that speculation on firm specific asymmetric information is the primary motive to trade on Malaysian stock market for the full and two sub-sample periods. The results show that most of the investors in Malaysian stock market tend to speculate firm related information to maximize their profits. The findings of this study provide important implications to policy makers in addition to investors in this developing market. Proper management of foreign portfolio investment is crucial to prevent manipulative moves and excessive speculative forms of portfolio investments that may cause excessive surges of inflows and massive panic outflows of short-term capital and thus collapse the financial system and downturn economy

d_{xy}-Density wave in fermion-fermion cold atom mixtures

We study density wave instabilities in a doubly-degenerate Fermi-Fermi mixture with $SU(2)\times SU(2)$ symmetry on a square lattice. For sufficiently large on-site inter-species repulsion, when the two species of fermions are both at half-filling, two conventional ($s$-wave) number density waves are formed with a $\pi$-phase difference between them to minimize the inter-species repulsion. Upon moving one species away from half-filling, an unconventional density wave with $d_{xy}$-wave symmetry emerges. When both species are away from the vicinity of half-filling, superconducting instabilities dominate. We present results of a functional renormalization-group calculation that maps out the phase diagram at weak couplings. Also, we provide a simple explanation for the emergence of the $d_{xy}$-density wave phase based on a four-patch model. We find a robust and general mechanism for $d_{xy}$-density-wave formation that is related to the shape and size of the Fermi surfaces. The density imbalance between the two species of fermions in the vicinity of half-filling leads to phase-space discrepancy for different inter-species Umklapp couplings. Using a phase space argument for leading corrections in the one-loop renormalization group approach to fermions, we show that the phase-space discrepancy in our system causes opposite flows for the two leading intra-species Umklapp couplings and that this triggers the $d_{xy}$-density-wave instability.Comment: revised long version; 8 pages, 7 figure

The Sources of Taiwan's Regional Unemployment : A Cross-Region Panel Analysis

In recent years under the trendof a global recession andd omestic structural change, the unemployment rate in Taiwan has reacheda recordhigh of above 5% which in turn has generateda series of social problems. Unemployment has now become the core issue in the government's agenda. From historical regional data, we findthat there are distinct variations of the unemployment rate among 23 cities andprefectures; moreover, this differentiation seems to persist over time. We analyze this regional unemployment trendby equilibrium and disequilibrium factors controlling for the macro environment using 23 cities' andprefectures' cross section and time series data pertaining to the 1995 to 2004 period. A cross-region panel study shows that the major factors that explain the persistent but divergent regional unemployment rates (aside from the aggregate macro environment which explains about one quarter) are demographic composition, family characteristics, industrial structure, population density, migration costs, and labor mobility. Understanding the sources of regional unemployment will help us to determine the appropriate policies to mitigate the unemployment rate across regions.Unemployment Rate, Demographic Composition, Compensating Wage Differentials, Urbanization, Labor Mobility, Migration

Decomposition of Lagrangian classes on K3 surfaces

We study the decomposability of a Lagrangian homology class on a K3 surface into a sum of classes represented by special Lagrangian submanifolds, and develop criteria for it in terms of lattice theory. As a result, we prove the decomposability on an arbitrary K3 surface with respect to the Kähler classes in dense subsets of the Kähler cone. Using the same technique, we show that the Kähler classes on a K3 surface which admit a special Lagrangian fibration form a dense subset also. This implies that there are infinitely many special Lagrangian 3-tori in any log Calabi-Yau 3-fold.https://arxiv.org/abs/2001.00202Othe

Data based identification and prediction of nonlinear and complex dynamical systems

We thank Dr. R. Yang (formerly at ASU), Dr. R.-Q. Su (formerly at ASU), and Mr. Zhesi Shen for their contributions to a number of original papers on which this Review is partly based. This work was supported by ARO under Grant No. W911NF-14-1-0504. W.-X. Wang was also supported by NSFC under Grants No. 61573064 and No. 61074116, as well as by the Fundamental Research Funds for the Central Universities, Beijing Nova Programme.Peer reviewedPostprin

Correlated Phases of Population Imbalanced Fermi-Fermi Mixtures on an Optical Lattice

We study a two species fermion mixture with different populations on a square lattice modeled by a Hubbard Hamiltonian with on-site inter-species repulsive interaction. Such a model can be realized in a cold atom system with fermionic atoms in two different hyperfine states loaded on an optical lattice and with tunable inter-species interaction strength via external fields. For a two-dimensional square lattice, when at least one of the fermion species is close to half-filling, the system is highly affected by lattice effects. With the majority species near half-filling and varying densities for the minority species, we find that several correlated phases emerge as the ground state, including a spin density wave state, a charge density wave state with stripe structure, and various p-wave BCS pairing states for both species. We study this system using a functional renormalization group method, determine its phase diagram at weak coupling, discuss the origin and characteristics of each phase, and provide estimates for the critical temperatures.Comment: 5 pages, 4 figures, figures update