A visual model for subband image coding

In this paper, we propose a visual model for the general subband coding system. This model is a generalization of Watson's visual model for DCT. Based on this model, a new perceptual distortion is proposed which can be used together with an efficient bit allocation algorithm to determine the quantizer stepsizes of subband coders. Simulation results and subjective viewing tests demonstrate that the proposed approach is very effective in improving the subjective quality of the encoded image at low bit rate.published_or_final_versio

Designing JPEG quantization matrix using rate-distortion approach and human visual system model

Towards the Knowledge Millennium, IEEE International Conference on Communications Proceedings, Montreal, Canada, 8-12 June 1997JPEG is an international standard for still image compression. The JPEG baseline algorithm allows users to supply the custom quantization table and Huffman table to control the compression ratio and the quality of the encoded image. Methods for determining the quantization matrix are usually based on i) rate-distortion theory and ii) spatial masking effects of the human visual system. In [2], Wu and Gersho proposed a recursive algorithm for generating picture-adaptive quantization tables based on rate-distortion approach but the complexity of the encoding algorithm is rather high. In this paper, we propose improvements to the Wu-Gersho's algorithm and a new bit allocation algorithm. Simulation results show that our new algorithm is superior to the Wu-Gersho's algorithm in terms of speed and peak signal to noise ratio (PSNR). Moreover, by incorporating the Human Visual System (HVS), our proposed coder can encode images with better visual quality.published_or_final_versio

Determination of the visibility thresholds for subband image coding

IEEE International Symposium on Circuits and Systems, Hong Kong, China, 9-12 June 1997In this paper, a method to determine the visibility thresholds for a given subband system is introduced. Our approach identifies the important worse case combination of the quantization error in each basis function and determine the corresponding visibility thresholds using results previously measured in the DCT domain. Using the proposed method, it is relatively simple to determine the visibility thresholds for any subband system in the YCrCb domain. Simulation results on the Lapped Orthogonal Transform (LOT) show that the visibility thresholds are useful in visually lossless coding and perceptual weighted quantization.published_or_final_versio

Understanding violence against Chinese women in Hong Kong: An analysis of risk factors with a special emphasis on the role of in-law conflict

This study examines risk factors of intimate partner violence against women in a cohort of Chinese women drawn from a large representative sample in Hong Kong. Data from a cross-section of 1,870 women are analyzed. Prevalence rates of women's self-reports of violence by their intimate partners and conflict with in-laws are computed and compared in terms of demographic and socioeconomic characteristics. The results show that in-law conflict was the characteristic most significantly associated with women's reports of violent victimization. This suggests that in-law conflict should be included in the screening and assessment of risk for intimate partner violence. © 2008 Sage Publications.postprin

Child maltreatment polyvictimization: Rates and short-term effects on adjustment in a representative Hong Kong sample

Objective: This article examines the unique effects of multiple forms of victimization, namely child abuse and neglect (CAN) and exposure to parental intimate partner violence (IPV), on children's self-blame, feelings of being threatened, self-esteem, and ability to control anger. Method: The cross-sectional study recruited a population-based sample of 2,062 children aged 12-17 years in Hong Kong. Structured questionnaires were used to collect data from the children. The prevalence rate of the co-occurrence of exposure to IPV and CAN in the Chinese population, and the unique impacts of exposure to IPV and CAN on children were examined. Results: The results show that 13.1% of the children had experienced CAN, and 6.5% had witnessed parental IPV. Among those families characterized by IPV, 61.1% were involved in child abuse in the preceding year of the study. Participants who had experienced both CAN and exposure to parental IPV reported lower levels of self-esteem and higher rates of being aggressive and violent, and feeling threatened. These children also reported the highest levels of feeling that their well-being was threatened and of blaming themselves for parental violence and parental discipline. Conclusions: The findings reemphasize the important need for public policy on child and youth victimization that encourages social workers and Child Protective Services to screen for child polyvictimization in cases of suspected/reported child abuse. © 2011 American Psychological Association.postprin

Childhood sexual abuse associated with dating partner violence and suicidal ideation in a representative household sample in Hong Kong

This study investigated the prevalence and impact of childhood sexual abuse (CSA) on future intimate partner violence (IPV) in dating relationship in Hong Kong, China. A total of 1,154 Chinese adult respondents engaged in dating relationships were interviewed face-to-face about their CSA histories, childhood witnessing of parental violence, adult sexual victimization (ASV) by others and IPV victimization with their current dating partner. Self-reports also measured levels of suicidal ideation, self-esteem, and demographic details. Overall, 1.7% reported some form of CSA with a higher percentage being women. No gender differences were found in the prevalence of either ASV or IPV. Results showed that CSA had an independent effect on physical IPV and suicidal ideation. The odds of IPV were increased by behavioral and psychological factors of victims such as alcohol and drug abuse, sex with partner, and low self-esteem. The odds of suicidal ideation were also increased by drug abuse, childhood witnessing of parental psychological aggression, and low self-esteem. Clinical implications of results included screening for CSA victims and suicidal victims when treating IPV patients, tailoring treatment according to individual IPV victim's problems, correcting behaviors that are associated with risks of IPV, such as engagement in casual sex and substance abuse, and focusing not only on tangible services but also on the social and psychological aspects that are placing the victims at risk for IPV. © The Author(s) 2011.postprin

Association between beta-blocker use and obesity in Hong Kong Chinese elders: a post-hoc analysis.

INTRODUCTION:Studies of Caucasian populations have shown that beta-blockers may exacerbate weight gain, a risk factor for many chronic diseases. Still, beta-blockers are the most prescribed antihypertensives in the Chinese population in Hong Kong. We aimed to explore the association between beta-blocker use, hypertension, and weight status of this population. METHODS:A post-hoc analysis regarding body mass index (BMI) and the use of beta-blockers was performed based on the medication profile of community-dwelling older adults. Participants' BMI, hypertension diagnosis, name, dose, frequency, route of administration of beta-blockers, and other drugs that may alter body weight were recorded. RESULTS:Of 1053 Chinese individuals aged ≥65 years (mean age 76.9±7.2 years, 80% female) from 32 elderly centres in Hong Kong, 18% (185/1053) of them consumed beta-blockers. That group also had a significantly larger proportion of obese individuals (45.9% vs 32.1%, P=0.002). After adjusting for other weight-altering drugs, beta-blockers remained a significant predictor of overweight and obesity (P=0.001). As the hypertensive population had significantly higher BMI than the normotensive population (24.3±3.6 vs 22.9±3.5, P<0.001), a sub-analysis on those with hypertension diagnosis confirmed that only the hypertensive population taking atenolol had a significantly larger population of obese individuals (BMI ≥25) compared with those who took metoprolol (58.9% vs 38.5%, P=0.03) and those who did not take any beta-blockers (58.9% vs 38.4%, P=0.007). CONCLUSIONS:Our findings taken together with other guideline reservations cast doubt on whether beta-blockers, particularly atenolol, should be the major drug prescribed to older adults with hypertension

Correlates of in-law conflict and intimate partner violence against chinese pregnant women in Hong Kong

This study examines correlates of in-law conflict with intimate partner violence (IPV) against pregnant women in a cohort of Chinese pregnant women who visited antenatal clinics in Hong Kong. This was a territory-wide, cross-sectional study of 3,245 pregnant women recruited from seven hospitals in Hong Kong. Participants were invited to complete the Chinese Abuse Assessment Screen and a demographic questionnaire. About 9% of the pregnant women reported having been abused by their partners in the preceding year. In-law conflict was the characteristic most significantly associated with preceding-year abuse against pregnant women, after controlling for covariates. Findings underscore the need to obtain information on in-law conflict as a risk factor for IPV. In-law conflict should be included in the assessment of risk for IPV. For the prevention of IPV, family-based intervention is needed to work with victims as well as in-laws. © 2009 Sage Publications.postprin

Implications of hydrocephalus upon presentation of tuberculous meningitis

Session - Neurosciencespublished_or_final_versio

Violence against pregnant women can increase the risk of child abuse: A longitudinal study

Objective: To assess the impact of intimate partner violence (IPV) against pregnant women on subsequent perpetration of child abuse and neglect (CAN) by parents; and to test the mediation effect of recent IPV on the link between IPV during pregnancy and subsequent CAN. Methods: This study was a longitudinal follow-up of a population-based study on pregnancy IPV conducted in antenatal clinics in 7 public hospitals in Hong Kong in 2005. Of all participants in the 2005 study, we recruited 487 women (with 184 having reported pregnancy IPV in the 2005 study) with newborn babies for a follow-up telephone interview in 2008. Participants responded to the Abuse Assessment Screen (AAS), the Parent-Child Conflict Tactics Scale, and some questions assessing demographic information. Results: The most common form of physical violence was corporal punishment, with a prevalence rate of 75.1% in the preceding year and 75.4% over their lifetime. Physical maltreatment was less likely to be reported, accounting for 4.7% in the preceding year and 4.9% over their lifetime. The preceding-year and lifetime prevalence rates of neglect were 11.3% and 11.5%, respectively. Findings from logistic regression analyses showed that IPV experienced by participants during pregnancy was associated with greater odds of both lifetime (aOR. =. 1.74) and preceding-year child physical maltreatment (aOR. =. 1.78). Results of the regression analyses also provided supportive evidence for the mediation effect of recent IPV victimization on the relationship between IPV during pregnancy and recent CAN against children. Conclusion: IPV against women during pregnancy predicted subsequent CAN on newborns in Chinese populations. This underscores the importance of screening pregnant women for IPV in order to prevent CAN at an early stage. Home visitations are suggested to break the cycle of violence within a nuclear family. © 2012 Elsevier Ltd.postprin