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BackgroundWith the world's largest population, HIV spread in China has been closely watched and widely studied by its government and the international community. One important factor that might contribute to the epidemic is China's numerous surplus of men, due to its imbalanced sex ratio in newborns. However, the sex ratio in the human population is often assumed to be 1:1 in most studies of sexually transmitted diseases (STDs). Here, a mathematical model is proposed to estimate the population size in each gender and within different stages of reproduction and sexual activities. This population profiling by age and gender will assist in more precise prediction of HIV incidences.MethodThe total population is divided into 6 subgroups by gender and age. A deterministic compartmental model is developed to describe birth, death, age and the interactions among different subgroups, with a focus on the preference for newborn boys and its impact for the sex ratios. Data from 2003 to 2007 is used to estimate model parameters, and simulations predict short-term and long-term population profiles.ResultsThe population of China will go to a descending track around 2030. Despite the possible underestimated number of newborns in the last couple of years, model-based simulations show that there will be about 28 million male individuals in 2055 without female partners during their sexually active stages.ConclusionThe birth rate in China must be increased to keep the population viable. But increasing the birth rate without balancing the sex ratio in newborns is problematic, as this will generate a large number of surplus males. Besides other social, economic and psychological issues, the impact of this surplus of males on STD incidences, including HIV infections, must be dealt with as early as possible.

A bias-variance dilemma in categorical data mining and analysis is the fact that a prediction method can aim at either maximizing the overall point-hit accuracy without constraint or with the constraint of minimizing the distribution bias. However, one can hardly achieve both at the same time. A scheme to balance these two prediction objectives is proposed in this article. An experiment with a real data set is conducted to demonstrate some of the scheme's characteristics. Some basic properties of the scheme are also discussed.

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Hemichorea induced by nonketotic hyperglycemia is a rare complication of diabetes mellitus. Here we present a case of 80-year-old female patient. She had a history of involuntary movement of the left body. Imaging examination showed abnormal signs of bilateral basal ganglia. After relevant treatment was conducted, the patient's hemichorea symptoms were significantly improved. Imaging features of nonketotic hyperglycemia Hemichorea plays a very important role in diagnosing and treatment of this disease. Introduction: Hemichorea refers to the involuntary movements of one or more limbs of the same side. These movements are continuous and irregular, variable amplitude, and usually involve the arms and legs together. Stroke is the most common reason, hyperglycemia is relatively rare. Characteristic imaging findings can be very suggestive of diagnosis, and also closely related to the development of disease. Here we present a case of hemichorea induced by nonketotic hyperglycemia which was confirmed by bilateral abnormal signals of basal ganglia in MRI.