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11.
Masaki Yamamoto Shuji Kijima Yasuko Matsui 《Journal of Combinatorial Optimization》2011,22(3):392-408
We present a polynomial-time perfect sampler for the Q-Ising with a vertex-independent noise. The Q-Ising, one of the generalized models of the Ising, arose in the context of Bayesian image restoration in statistical mechanics.
We study the distribution of Q-Ising on a two-dimensional square lattice over n vertices, that is, we deal with a discrete state space {1,…,Q}
n
for a positive integer Q. Employing the Q-Ising (having a parameter β) as a prior distribution, and assuming a Gaussian noise (having another parameter α), a posterior is obtained from the Bayes’ formula. Furthermore, we generalize it: the distribution of noise is not necessarily
a Gaussian, but any vertex-independent noise. We first present a Gibbs sampler from our posterior, and also present a perfect
sampler by defining a coupling via a monotone update function. Then, we show O(nlog n) mixing time of the Gibbs sampler for the generalized model under a condition that β is sufficiently small (whatever the distribution of noise is). In case of a Gaussian, we obtain another more natural condition
for rapid mixing that α is sufficiently larger than β. Thereby, we show that the expected running time of our sampler is O(nlog n). 相似文献
12.
莫高窟初唐窟群当中, 329窟和 331窟的壁画在画功特色上存在 某些共同之处。上述画功特色接近贞观年间的洞窟,但与武则天时期的洞窟差异 比较大。 相似文献
13.
For square contingency tables with ordered categories, there may be some cases that one wants to analyze them by considering collapsed tables with some adjacent categories combined in the original table. This paper considers the symmetry model for collapsed square contingency tables and proposes a measure to represent the degree of departure from symmetry. The proposed measure is defined as the arithmetic mean of submeasures each of which represents the degree of departure from symmetry for each collapsed 3×3 table. Each submeasure also represents the mean of power-divergence or diversity index for each collapsed table. Examples are given. 相似文献
14.
Most research on access to health care focuses on individual-level determinants such as income and insurance coverage. The role of community-level factors in helping or hindering individuals in obtaining needed care, however, has not received much attention. We address this gap in the literature by examining how neighborhood socioeconomic disadvantage is associated with access to health care. We find that living in disadvantaged neighborhoods reduces the likelihood of having a usual source of care and of obtaining recommended preventive services, while it increases the likelihood of having unmet medical need. These associations are not explained by the supply of health care providers. Furthermore, though controlling for individual-level characteristics reduces the association between neighborhood disadvantage and access to health care, a significant association remains. This suggests that when individuals who are disadvantaged are concentrated into specific areas, disadvantage becomes an "emergent characteristic " of those areas that predicts the ability of residents to obtain health care. 相似文献
15.
This paper constructs an overlapping-generations model with two different types of technology: modern, which can be accessed
only by the skilled, and traditional, which can be accessed by the unskilled. The model described in this paper shows that
a rise in the wage premium for skilled workers caused by skill-biased technological changes explains the following key stylized
facts: with economic development, the fraction of skilled people increases, the fertility rate declines, and income inequality
rises and then falls. The model also explains the observed gradual rises in income inequality in developed countries.
相似文献
16.
After the Asian crisis in 1997, the respective trade balances of Indonesia, Korea, Malaysia, and Thailand reversed suddenly from deficit to surplus. By particularly addressing the sudden cessation of investment caused by the financial crisis, it is demonstrated that the IS balance adjustment dominates real exchange rate depreciation, indicating that to reform the large external imbalance of Asian countries, which is a major component of global imbalance, policymakers should target domestic absorption. Furthermore, it can be demonstrated that the large trade balance surplus of Asian countries will decrease along with recovery. Finally, policy implications related to the recent Euro crisis are provided. 相似文献
17.
The likelihood ratio test (LRT) for the mean direction in the von Mises distribution is modified for possessing a common asymptotic distribution both for large sample size and for large concentration parameter. The test statistic of the modified LRT is compared with the F distribution but not with the chi-square distribution usually employed, Good performances of the modified LRT are shown by analytical studies and Monte Carlo simulation studies, A notable advantage of the test is that it takes part in the unified likelihood inference procedures including both the marginal MLE and the marginal LRT for the concentration parameter. 相似文献
18.
Kahoruko Yamamoto 《International Journal of Japanese Sociology》2000,9(1):121-136
Abstract This paper will investigate how some undocumented migrant workers survive in Kotobuki, Yokohama known as the urban underclass. Since the latter half of the 1990s, Kotobuki itself has undergone structural changes. Once a center of day laborers it is now a center of older ex-laborers, mostly surviving on welfare. However, Kotobuki holds positive associations for many Korean and Pilipino migrants, many of whom arrived at the end of the 1980s. They regard the area as a place to earn high wages and as a center for building ethnic networks. Migrants tend to help their ethnic fellows find jobs and exchange information that they may otherwise be unable to acquire given that undocumented migrants are ineligible for public services in Japan. Additionally, ethnic-related self-help activities as well as NGOs play a valuable role in sustaining the livelihood of such migrants who are denied access to public services and assistance. This paper will illustrate the role of self-help among ethnic minority migrant workers. It also aims to demonstrate that contrary to prevailing assumptions, their social status as underclass is not lower than that of their Japanese counterparts. 相似文献
19.
To investigate how fertility rates interrelate with the modern economy, we construct a simple model in which variety expansion of consumption goods reduces fertility rates. In our model, variety expansion reduces the relative price of a composite of differentiated goods compared to child-rearing costs. Thus, parents raise the expenditure share for differentiated goods and lower the number of children. We show that this model can be applied to a growth model in which economic growth progresses with variety expansion of consumption goods and fertility rates decrease with economic growth. Thus, we show a new mechanism for fertility decline, and this mechanism can be applied to a growth model. 相似文献
20.
Tomoyo Koyanagi Yoshinobu Kusumoto Shori Yamamoto Kazuhiko Takeuchi 《Urban Ecosystems》2012,15(4):893-909
By comparing with the historic semi-natural grassland and woodland vegetation data compiled in the 1970s and 1980s, we aimed to reveal potential roles of small and linear habitat fragments remaining in the urbanized satoyama landscape (i.e., agricultural landscape) in Japan for conservation of grassland plant species. TWINSPAN cluster analysis differentiated the current vegetation from historic one. Current vegetation of Miscanthus grassland was classified into two different groups and one of the two was equivalent to current understory vegetation of fragmented woodland. The linear woodland edge vegetation along the roads was classified into one group and separated from the other current vegetation groups. The current vegetation groups were characterized by higher richness of exotic species than historic vegetation groups. Detrended correspondence analysis (DCA) revealed that there were no groups of current vegetation that is equivalent to historic woodland understory vegetation. The vegetation quality of the current group of Miscanthus grassland and secondary woodland remaining on urban public properties, and the group of linear roadside vegetation were almost equivalent to that of historic semi-natural grassland. Both of the small and linear habitat fragments might have functioned as habitats for grassland species under regular mowing management. Although small and linear habitat fragments would not be sufficient for sustaining grassland populations in the future, these habitats can serve as key reservoirs for grassland species recovery in the conservation and restoration of grassland communities in the urbanized satoyama landscape. 相似文献