Housing Demand with Random Group Effects

This paper examines the random group effect, which has usually not been considered in traditional housing demand studies. Frequently, group level variables are used in housing demand estimation due to the data constraint. For instance, the US Index of Housing Price per administrative area is often used to measure the housing price when estimating the US price elasticity of demand for housing, and the average household income is often used as a proxy for the individual income in Taiwan when estimating the income elasticity of demand for housing. Econometricians argue that the traditional OLS estimation, when the random group effect is ignored, has been considered to have a downward bias in the estimated standard error. By following Amemiya (1978) and Borjas and Sueyoshi (1994), we propose a two-stage estimation technique to estimate housing demand with the random group effect. Using Taiwan’s cross-sectional survey data, we found that the standard error of the estimated coefficient for the group level income variable is underestimated in the traditional unadjusted OLS specification. This finding suggests that there may be a danger of spurious regression in the traditional OLS housing demand estimation.Housing Demand, Random Group Effect, Two-stage Estimation

catena-Poly[[[tetra­aqua­zinc(II)]-μ-4,4′-bipyridine-κ2 N:N′] naphthalene-1,5-disulfonate]

In the title complex, {[Zn(C10H8N2)(H2O)4](C10H6O6S2)}n, the [Zn(4,4′-bipy)(H2O)4]2+ (4,4′-bipy is 4,4′-bipyridine) cations are linked into linear chains along [001] by the 4,4′-bipy ligands. The ZnII ion exhibits a slightly distorted octa­hedral coordination geometry in which the four water mol­ecules are in the equatorial positions. The anions are hydrogen bonded to the polycationic chains by O—H⋯O hydrogen bonds, forming a three-dimensional network. The ZnII ion, 4,4′-bipy ligand and anion lie on special positions of 2/m site symmetry

Topological and organizational properties of the products of house-keeping and tissue-specific genes in protein-protein interaction networks

<p>Abstract</p> <p>Background</p> <p>Human cells of various tissue types differ greatly in morphology despite having the same set of genetic information. Some genes are expressed in all cell types to perform house-keeping functions, while some are selectively expressed to perform tissue-specific functions. In this study, we wished to elucidate how proteins encoded by human house-keeping genes and tissue-specific genes are organized in human protein-protein interaction networks. We constructed protein-protein interaction networks for different tissue types using two gene expression datasets and one protein-protein interaction database. We then calculated three network indices of topological importance, the degree, closeness, and betweenness centralities, to measure the network position of proteins encoded by house-keeping and tissue-specific genes, and quantified their local connectivity structure.</p> <p>Results</p> <p>Compared to a random selection of proteins, house-keeping gene-encoded proteins tended to have a greater number of directly interacting neighbors and occupy network positions in several shortest paths of interaction between protein pairs, whereas tissue-specific gene-encoded proteins did not. In addition, house-keeping gene-encoded proteins tended to connect with other house-keeping gene-encoded proteins in all tissue types, whereas tissue-specific gene-encoded proteins also tended to connect with other tissue-specific gene-encoded proteins, but only in approximately half of the tissue types examined.</p> <p>Conclusion</p> <p>Our analysis showed that house-keeping gene-encoded proteins tend to occupy important network positions, while those encoded by tissue-specific genes do not. The biological implications of our findings were discussed and we proposed a hypothesis regarding how cells organize their protein tools in protein-protein interaction networks. Our results led us to speculate that house-keeping gene-encoded proteins might form a core in human protein-protein interaction networks, while clusters of tissue-specific gene-encoded proteins are attached to the core at more peripheral positions of the networks.</p

Predictability of the corneal flap creation with the VisuMax femtosecond laser in LASIK

AIM: To observe the predictability of corneal flap creation with the VisuMax femtosecond laser and preliminarily analyze the factors correlated to the thickness and diameter of the flap. <p>METHODS: This retrospective case series study included 300 eyes of 150 consecutive patients. The eyes were assigned to two groups according to intended flap thickness, 100μm(204 eyes)and 110μm(96 eyes), which created with the VisuMax femtosecond laser. Intended flap diameters were 7.9mm and 8.3mm. Difference analysis of flap diameter and intended diameter as well as flap thickness and intended thickness were made. The data were analyzed with SPSS to sum up a multiple stepwise regression formula that could express their quantitative relationship. <p>RESULTS: The 100μm flap group had an average flap thickness of 103.11±4.07μm, while for the 110μm group the average flap thickness was 113.35±5.71μm. The difference between right and left eyes was not statistically significant(<i>t</i>_100μm =-0.901, <i>t</i> _110μm=-0.490; <i>P</i>>0.05). Corneal flap thickness was not related to flap diameter(<i>r</i>=0.003, 0.018; <i>P</i>>0.05), preoperative patient age(<i>r</i>=0.022, 0.050; <i>P</i>>0.05), corneal thickness(<i>r</i>=0.051, 0.101; <i>P</i>>0.05), keratometric value K(<i>r</i>=-0.048, -0.136; <i>P</i>>0.05)or intraocular pressure(<i>r</i>=-0.113, 0.047; <i>P</i>>0.05). Preoperative corneal keratometric value K was positively correlated with corneal flap diameter(<i>r</i>=0.359, 0.532; <i>P</i>=0.01, 0.007<0.05). <p>CONCLUSION:The LASIK flap creation with the VisuMax femtosecond laser has relatively good predictability. There is no influencing factor for flap thickness

2-(4-Methyl­phen­yl)-5-[({[5-(4-methyl­phen­yl)-1,3,4-thia­diazol-2-yl]sulfan­yl}meth­yl)sulfan­yl]-1,3,4-thia­diazole

In the title compound, C19H16N4S4, the mol­ecules exhibit a butterfly conformation, where the thia­diazole and attached benzene rings in two wings are almost coplanar, with dihedral angles of 0.8 (3) and 0.9 (3)°, respectively, while the two thia­diazole rings form a dihedral angle of 46.3 (3)°