Inverse Demand Systems for Composite Liquid Assets: Evidence from China

This paper applies the concept of inverse demands and its related scale and substitution effects to model the demand for liquid assets in China. We also propose a new model, termed the Modified Almost Ideal Inverse Demand System (MAIIDS), which nests the Almost Ideal Inverse Demand System (AIIDS) as a special case. We estimate this new model and its special case by using Chinese panel data and find it statistically superior to the AIIDS. Results also reveal the improved regularity features of the MAIIDS, and show that demand patterns of liquid assets across different income groups in China are distinctive.AIIDS; MAIIDS; Regularity; Liquid assets.

Requiem for an FCHAMP?

Fractionally charged massive particles (FCHAMPs) appear in extensions of the standard model, especially those with superstring constructions. The lightest FCHAMP would be absolutely stable and any produced during the early evolution of the Universe would be present today. The production, annihilation, and survival of L, a lepton with electroweak but no strong interactions, of mass m_L and charge Q_L (in units of the positron charge) are explored. Since massive charged particles behave like baryons, primordial nucleosynthesis and the cosmic background radiation temperature anisotropies limit the FCHAMP relic density leading to constraints on the Q_L - m_L relation. Further constraints are provided by the invisible width of the Z and by accelerator searches for massive, charged particles. We exploit the fact that in the early Universe the negatively charged L will combine with alpha particles and protons forming tightly bound, positively charged states. The Coulomb barriers between these positively charged bound states and the free L+ suppress late time annihilation in the Galaxy and on Earth, limiting any late-time reduction of relic FCHAMP pairs. The surviving FCHAMP abundance on Earth is orders of magnitude higher than the limits from terrestrial searches for fractionally charged particles, appearing to close the window on FCHAMPs. However, as Q_L approaches an integer these searches become increasingly insensitive, leaving some "islands" in the Q_L - m_L plane which may be explored by searching for FCHAMPs in the cosmic rays.Comment: 13 pages, 9 figures, version accepted for publication in PRD, including a new constraint from the D0 experimen

Fermions on Colliding Branes

We study the behaviour of five-dimensional fermions localized on branes, which we describe by domain walls, when two parallel branes collide in a five-dimensional Minkowski background spacetime. We find that most fermions are localized on both branes as a whole even after collision. However, how much fermions are localized on which brane depends sensitively on the incident velocity and the coupling constants unless the fermions exist on both branes.Comment: 8 pages 7 figure

The Impact of Ownership Reform in Chinese Industry, 1995-2001

During the 1980s, the restructuring of Chinese industry was driven principally by the entry of new enterprises into the enterprise system and by the restructuring of managerial incentives. In 1993, China’s leadership formally inaugurated the shareholding experiment. This paper examines the impact on eight performance measures of the conversion of both state- and collective-owned enterprises to shareholding enterprises. The analysis distinguishes between the direct effect of conversion and the induced effect, involving the attraction of non-state investment, which reduces the proportion of state assets and state control rights. We find evidence for SOEs that both conversion and a decline in the share of state-owned assets motivate rising productivity and R&D intensity. While rising proportions of non-state assets motive lower employment and rising wages, the initial conversion effect is associated with higher employment and lower wages. These latter impacts may result from agreements with workers as part of the conversion process. The SOE conversion process exhibits selection bias in which SOEs with high rates of capital productivity and profitability, high tax burdens, and comparatively low wages and smaller labor forces are more likely to be selected for conversion. No similar selection bias is evident in the collective sector.http://deepblue.lib.umich.edu/bitstream/2027.42/39927/3/wp542.pd

Multiscale Modelling of Self-assembly in Soft Matter

This thesis presents all-atom molecular dynamics simulations and the development of coarse-grained models for various classes of liquid crystals. The overall aim was to parametrise chemically specific models, propagating information between different resolutions through multiscale modelling approaches, to investigate hierarchical self-assembly in soft matter systems. Common coarse-graining methods were assessed in terms of their representability and transferability for applications involving thermotropic calamitic and discotic mesogens, and lyotropic chromonic liquid crystals. Extensive all-atom simulations were performed on: bent liquid crystal dimers, such as CB7CB; ionic cyanine dyes in aqueous solution (PIC, PCYN, TTBC and BIC); a chromonic perylene bisimide dye (PER); and its thermotropic discotic analogue (PEROEG). These serve as references to parametrise/validate lower resolution models and to provide insights into these systems at the molecular level. For CB7CB, the twist-bend nematic (NTB) phase is observed and characterised. The self-assembly of cyanine dyes and chromonic mesogens was studied by calculating $\Delta G_{\rm{assoc}}$, $\Delta H_{\rm{assoc}}$ and $\Delta S_{\rm{assoc}}$ for the association of $n$-mers (where $n$ = 2, 3 or 4). Structures of H-aggregate stacks, with shift and Y junction defects, and J-aggregates with a brickwork arrangement were detected. Coarse-graining approaches including iterative Boltzmann inversion (IBI), multiscale coarse-graining (MS-CG) in the form of hybrid force matching (FM) and the Martini 3 force field were utilised for the aforementioned systems. A FM model of CB7CB demonstrates high representability and transferability; the NTB phase is captured and the full phase diagram can be explored via heating or cooling. An optimised Martini model correctly exhibits the chromonic nematic and hexagonal phases for PER at the expected concentrations. For PEROEG, an IBI model was found to be superior in modelling the columnar-hexagonal phase. This thesis discusses, in detail, the successes and failures of the various coarse-graining strategies. While successful coarse-graining of liquid crystals remains a challenge, this thesis demonstrates that, with the right choice of method, high-quality coarse-grained models can be developed for both thermotropic and lyotropic systems

Identifying Patterns in Behavioral Public Health Data Using Mixture Modeling with an Informative Number of Repeated Measures

Finite mixture modeling is a useful statistical technique for clustering individuals based on patterns of responses. The fundamental idea of the mixture modeling approach is to assume there are latent clusters of individuals in the population which each generate their own distinct distribution of observations (multivariate or univariate) which are then mixed up together in the full population. Hence, the name mixture comes from the fact that what we observe is a mixture of distributions. The goal of this model-based clustering technique is to identify what the mixture of distributions is so that, given a particular response pattern, individuals can be clustered accordingly. Commonly, finite mixture models, as well as the special case of latent class analysis, are used on data that inherently involve repeated measures. The purpose of this dissertation is to extend the finite mixture model to allow for the number of repeated measures to be incorporated and contribute to the clustering of individuals rather than measures. The dimension of the repeated measures or simply the count of responses is assumed to follow a truncated Poisson distribution and this information can be incorporated into what we call a dimension informative finite mixture model (DIMM). The outline of this dissertation is as follows. Paper 1 is entitled, "Dimension Informative Mixture Modeling (DIMM) for questionnaire data with an informative number of repeated measures." This paper describes the type of data structures considered and introduces the dimension informative mixture model (DIMM). A simulation study is performed to examine how well the DIMM fits the known specified truth. In the first scenario, we specify a mixture of three univariate normal distributions with different means and similar variances with different and similar counts of repeated measurements. We found that the DIMM predicts the true underlying class membership better than the traditional finite mixture model using a predicted value metric score. In the second scenario, we specify a mixture of two univariate normal distributions with the same means and variances with different and similar counts of repeated measurements. We found that that the count-informative finite mixture model predicts the truth much better than the non-informative finite mixture model. Paper 2 is entitled, "Patterns of Physical Activity in the Northern Manhattan Study (NOMAS) Using Multivariate Finite Mixture Modeling (MFMM)." This is a study that applies a multivariate finite mixture modeling approach to examining and elucidating underlying latent clusters of different physical activity profiles based on four dimensions: total frequency of activities, average duration per activity, total energy expenditure and the total count of the number of different activities conducted. We found a five cluster solution to describe the complex patterns of physical activity levels, as measured by fifteen different physical activity items, among a US based elderly cohort. Adding in a class of individuals who were not doing any physical activity, the labels of these six clusters are: no exercise, very inactive, somewhat inactive, slightly under guidelines, meet guidelines and above guidelines. This methodology improves upon previous work which utilized only the total metabolic equivalent (a proxy of energy expenditure) to classify individuals into inactive, active and highly active. Paper 3 is entitled, "Complex Drug Use Patterns and Associated HIV Transmission Risk Behaviors in an Internet Sample of US Men Who Have Sex With Men." This is a study that applies the count-informative information into a latent class analysis on nineteen binary drug items of drugs consumed within the past year before a sexual encounter. In addition to the individual drugs used, the mixture model incorporated a count of the total number of drugs used. We found a six class solution: low drug use, some recreational drug use, nitrite inhalants (poppers) with prescription erectile dysfunction (ED) drug use, poppers with prescription/non-prescription ED drug use and high polydrug use. Compared to participants in the low drug use class, participants in the highest drug use class were 5.5 times more likely to report unprotected anal intercourse (UAI) in their last sexual encounter and approximately 4 times more likely to report a new sexually transmitted infection (STI) in the past year. Younger men were also less likely to report UAI than older men but more likely to report an STI

The Impact of Ownership Reform in Chinese Industry, 1995-2001

During the 1980s, the restructuring of Chinese industry was driven principally by the entry of new enterprises into the enterprise system and by the restructuring of managerial incentives. In 1993, China’s leadership formally inaugurated the shareholding experiment. This paper examines the impact on eight performance measures of the conversion of both state- and collective-owned enterprises to shareholding enterprises. The analysis distinguishes between the direct effect of conversion and the induced effect, involving the attraction of non-state investment, which reduces the proportion of state assets and state control rights. We find evidence for SOEs that both conversion and a decline in the share of state-owned assets motivate rising productivity and R&D intensity. While rising proportions of non-state assets motive lower employment and rising wages, the initial conversion effect is associated with higher employment and lower wages. These latter impacts may result from agreements with workers as part of the conversion process. The SOE conversion process exhibits selection bias in which SOEs with high rates of capital productivity and profitability, high tax burdens, and comparatively low wages and smaller labor forces are more likely to be selected for conversion. No similar selection bias is evident in the collective sector.