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

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

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

Associating pregnancy with partner violence against Chinese women

The present study discusses if pregnancy is a risk factor for intimate partner violence using a large, representative sample containing detailed information on partner violence including physical and sexual abuse as well as perpetrator-related risk factors. Data from a representative sample of 2,225 men were analyzed. The self-reported prevalence of men's violence against their female partners was computed and compared in terms of demographic, behavioral, and relationship characteristics. The preceding-year prevalence of physical assault, sexual violence, and "any violence or injury" among the group whose partners were pregnant was 11.9%, 9.1%, and 18.8%, respectively. This is significantly higher than the nonpregnant group. Pregnancy was significantly associated with increased odds of violence, including physical assault, sexual violence, and "any violence or injury" (ORs = 2.42, 2.42, and 2.60, respectively). Having controlled for relationship characteristics including social desirability, social support, in-law conflict, dominance, and jealousy of male perpetrators, pregnancy was significantly associated with "any violence or injury." Demographic and behavioral variables accounted for pregnant women's significantly higher odds of having been abused in the year preceding the data collection. This study provides preliminary findings on the association between pregnancy and partner violence. Our findings underscore the need to screen for violence among pregnant women in clinical health care settings as well as in communities. Perpetrator-related risk factors should be included in the assessment of risk for partner violence against pregnant women. For the prevention of intimate partner violence, family-based intervention is needed to work with victims as well as perpetrators. © The Author(s) 2011.postprin

Psychological intimate partner abuse among Chinese women: What we know and what we still need to know

Although increasing attention has been given to psychological abuse in intimate partner relationships, relatively little is known about this complex problem among Chinese women. A better understanding of psychological abuse in Chinese intimate relationships is warranted because Chinese culture is shame-oriented. Women, therefore, may be more susceptible to shameful feelings induced by psychological abuse. This may explain why psychological abuse, in the absence of physical and/or sexual abuse, has such adverse mental health effects on Chinese women. In this paper, what is known about psychological abuse in Chinese intimate relationships and what still needs to be known are highlighted, together with the mental health impact. Implications for future research are also presented.published_or_final_versio

Diurnal cortisol slope mediates the association between affect and memory retrieval in older adults with mild cognitive impairment: a path-analytical study

Background: Memory deficits are linked to dysfunctional HPA axis activity and negative affect in older adults. This study evaluated the mediating effect of the diurnal cortisol pattern on the relationship between affect and memory in older people with mild cognitive impairment (MCI). Methods: This longitudinal study recruited 189 Chinese older adults with MCI from elderly centers in Hong Kong. The participants completed assessments of affect, salivary cortisol, and digit spans at baseline; neurocognitive assessments on verbal fluency, memory retrieval, and digit spans at 6-month follow-up; and instrumental activities of daily living (IADL) at 1-year follow-up. Structural equation modeling examined the direct and indirect effects of negative affect on memory and IADL via diurnal cortisol pattern. Results: Controlling for covariates, negative affect significantly predicted flattened diurnal cortisol slopes (β = 0.17, p < 0.05) but not memory or IADL (p = 0.23 – 0.91) directly. Diurnal cortisol slopes negatively predicted memory retrieval (β = −0.20, p < 0.05), which in turn positively predicted IADL (β = 0.22, p < 0.01). The indirect effect from negative affect to IADL via cortisol slope and memory retrieval was significant and negative (αβγ = −0.05, 95% bootstrapped CI = −0.248 to −0.001). Discussion: The present study established certain temporal linkages among affect and cortisol slopes at baseline, memory retrieval at 6 months, and functional decline 1 year later in older adults with MCI. Flattened diurnal cortisol slopes might mediate the detrimental effects of negative affect on memory retrieval and functioning across 1 year

Short-Term Prognosis of Transient Ischemic Attack and Predictive Value of the ABCD2 Score in Hong Kong Chinese

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