First-principles study of the lattice dynamics of Sb2S3

We present a lattice dynamics study of orthorhombic antimony sulphide (Sb2S3) obtained using density-functional calculations in conjunction with the supercell force-constant method. The effect of Born effective charges is taken into account using a mixed-space approach, resulting in the splitting of longitudinal and transverse optical (LO-TO) phonon branches near the zone center. Zone-center frequencies agree well with Raman scattering experiments. Due to the slow decay of the interatomic force constants (IFC), a minimal 2x4x2 supercell (Pnma setting) with 320 atoms is crucial for an accurate determination of the dispersion relations. Smaller supercells result in artificial acoustic phonon softening and unphysical lifting of degeneracies along high symmetry directions. We propose a scheme to investigate the convergence of the IFC with respect to the supercell sizes. The phonon softening can be attributed to the periodic images that affect the accuracy of the force constants, and the truncation of long-ranged forces. The commensuration of the q-vectors with the supercell size is crucial to preserve degeneracies in Sb2S3 crystals.Comment: 7 pages 4 figures, 3 table

Model peptides to study the effects of P2 and P3 substitutions in statine-containing HIV proteinase inhibitors

AbstractThrough a series of synthetic model peptides, we have examined the structural requirements of the P2 and P3 residues in statine-based HIV protease (PR) inhibitors. Results agree with the general observations that, the more bulky the P3 aromatic hydrophobic side chain, the more potent is the inhibitor. At P2, an isopropyl side chain is critical in maintaining potency. Three-dimensional modeling demonstrates that the steric bulk of a leucyl residue or the unfavorable energy transfer, from water to enzyme, for a basic amino acid residue at P2 markedly compromises activity. A naphthylalaninyl-valyl P3-P2 substituted analogue inhibits PR with an IC50 value of 6 nM, and was also effective as an antiviral agent

New tests of calendar effects on equity and securitized real estate markets

We construct two new tests of calendar effects, apply them on 12 stock indices during 1996–2016, and compare the results with that using Hui and Chan (2016)’s method. The results show that the January and Halloween effects are significant for the four western generalized equity indices for small moving-window sizes. Furthermore, the securitized real estate indices show a greater difference in the overall calendar effect between the three methods than the general equity indices do. This study has an implication that a certain sector of the market is riskier than the whole market

Contagion across real estate and equity markets during European sovereign debt crisis

Standard methods of testing contagion may not work well if the data set is not normally distributed. To cope with this problem, Hatemi-J and Hacker (2005) proposed a new case-resampling bootstrap method to test contagion. In this paper, we extend this method to test the parameters in the Forbes-Rigobon multivariate (FRM) test. The new method has the advantage that the bivariate model is extended to a multivariate framework which jointly models and tests all combinations of contagious linkages. We apply our method to investigate contagion across equity and real estate markets of four countries: Greece, U.K., U.S. and Hong Kong, during the European sovereign debt crisis, and compare the result with that by performing the FRM test directly. Two important results are found. Firstly, both tests we use give similar p-values of the coefficients which indicate the significance of contagion. Secondly, for both tests, the contagion pattern in the equity and real estate markets are different. Our study has an implication to investors that they should regularly review their portfolio and be aware of contagion triggered by a crisis. This would help them reduce their loss and is useful in strategic property management

A new time-dependent trading strategy for securitized real estate and equity indices

The “buy-and-hold” strategy based on the EMH has been adopted by many investors for long. However, the global financial crisis in 2008 caused more doubt to be cast on EMH. Therefore, many scholars have attempted to create a trading strategy which can outperform the “buy-and-hold” strategy. In this study, we use the Shiryaev-Zhou index to derive a new generalized time-dependent strategy of which the moving-window size can be changed to see how the moving-window size affects the resulting profit of our strategy. We test our strategy on the securitized real estate and general equity indices of six economies, and find the optimal moving-window size for our strategy on each stock index. The results show that when the optimal moving-window size is used, our strategy outperforms the “buy-and-hold” strategy for most cases. Furthermore, during stock market downturns, it’s advisable to adopt our strategy, preferably with larger moving-window sizes, to prevent losses when the stock prices fall rapidly. However, during long periods of booms, it’s better to adhere to the “buy-and-hold” strategy. This implies that we should switch strategies when market fundamentals changes significantly. Property practitioners can also apply this strategy for a better portfolio management to increase their profit. First published online 29 September 201

Are the global real estate markets contagious?

The aim of this paper is to investigate the contagion across real estate markets of four countries: Hong Kong, China, U.S. and U.K., during the financial tsunami in 2008. We use the Forbes-Rigobon test, the coskewness test and the cokurtosis test. We propose a new cokurtosis test constructed by extending the method of constructing the coskewness test to further higher order moments. It can show additional channels of contagion that other tests fail to show, and hence can provide more information on the direction of contagion, and reflect a more complete picture of the contagion pattern. The coskewness and cokurtosis tests show that contagion exists between the four countries, and the contagion effect is stronger between Hong Kong and China, and between U.S. and U.K. This provides clues for investors on how to diversify their investment to reduce their risk. This paper bridges the gap that previous works on contagion across real estate markets give mixed results, and gives a first insight into the contagion pattern of global real estate markets during the financial tsunami

Does EVA truly reflect the performance of property companies in China?

This study investigates the economic value added (EVA) of 18 major Chinese property companies from 2006 to 2012. We categorize the companies in two ways: 1) companies concentrating on property vs multi-functional companies and 2) state-owned enterprises (SOEs) vs privately-owned enterprises (POEs). We find that on average, the mainland property companies experienced a negative EVA during the period 2006–2012. This is due to the companies undertaking long-term projects, and the companies do not recognize capital gain from property appreciation as income. Hence the EVA of the companies is, in fact, understated. The results also reveal that POEs outperform SOEs in terms of EVA. This reflects the inefficiency of SOEs. This research has two important implications to investors. Firstly, besides looking at the EVA of the companies, investors should also understand the nature of businesses of the companies thoroughly. Secondly, investors investing in emerging markets like China should have a thorough understanding of their market characteristics. This study can act as a reference for future studies in EVA of property companies in other emerging economies in the world

The role of capital controls in mediating global shocks

To compare the effect of oral glucose given with or without facilitated tucking (FT), versus placebo (water) to facilitate image acquisition during a targeted neonatal echocardiography (TNE).Factorial, double blind, randomized controlled trial.Tertiary neonatal intensive care unit (NICU).Infants born between 26 and 42 weeks of gestation (GA).One of four treatment groups: oral water (placebo), oral glucose (25%), facilitated tucking with oral water or facilitated tucking with oral glucose, during a single, structured TNE. All infants received a soother.Change in Behavioral Indicators of Infant Pain (BIIP) scores.104 preterm infants were randomized (mean ± SD GA: 33.4 ± 3.5 weeks). BIIP scores remained low during the echocardiography scan (median, [IQ range]: 0, [0 to 1]). There were no differences in the level of agitation of infants amongst the treatment groups, with estimated reductions in mean BIIP relative to control of 0.27 (95%CI -0.40 to 0.94) with use of oral glucose and .04 (-0.63 to 0.70) with facilitated tucking. There were also no differences between treatment groups in the quality and duration of the echocardiography scans.In stable infants in the NICU, a TNE can be performed with minimal disruption in a majority of cases, simply by providing a soother. The use of 25% glucose water in this context did not provide further benefit in reducing agitation and improving image acquisition.Clinical Trials.gov: NCT01253889