Norm-Explicit Quantization: Improving Vector Quantization for Maximum Inner Product Search

Vector quantization (VQ) techniques are widely used in similarity search for data compression, fast metric computation and etc. Originally designed for Euclidean distance, existing VQ techniques (e.g., PQ, AQ) explicitly or implicitly minimize the quantization error. In this paper, we present a new angle to analyze the quantization error, which decomposes the quantization error into norm error and direction error. We show that quantization errors in norm have much higher influence on inner products than quantization errors in direction, and small quantization error does not necessarily lead to good performance in maximum inner product search (MIPS). Based on this observation, we propose norm-explicit quantization (NEQ) --- a general paradigm that improves existing VQ techniques for MIPS. NEQ quantizes the norms of items in a dataset explicitly to reduce errors in norm, which is crucial for MIPS. For the direction vectors, NEQ can simply reuse an existing VQ technique to quantize them without modification. We conducted extensive experiments on a variety of datasets and parameter configurations. The experimental results show that NEQ improves the performance of various VQ techniques for MIPS, including PQ, OPQ, RQ and AQ

Comparative Analyses of Pandemic H1N1 and Seasonal H1N1, H3N2, and Influenza B Infections Depict Distinct Clinical Pictures in Ferrets

Influenza A and B infections are a worldwide health concern to both humans and animals. High genetic evolution rates of the influenza virus allow the constant emergence of new strains and cause illness variation. Since human influenza infections are often complicated by secondary factors such as age and underlying medical conditions, strain or subtype specific clinical features are difficult to assess. Here we infected ferrets with 13 currently circulating influenza strains (including strains of pandemic 2009 H1N1 [H1N1pdm] and seasonal A/H1N1, A/H3N2, and B viruses). The clinical parameters were measured daily for 14 days in stable environmental conditions to compare clinical characteristics. We found that H1N1pdm strains had a more severe physiological impact than all season strains where pandemic A/California/07/2009 was the most clinically pathogenic pandemic strain. The most serious illness among seasonal A/H1N1 and A/H3N2 groups was caused by A/Solomon Islands/03/2006 and A/Perth/16/2009, respectively. Among the 13 studied strains, B/Hubei-Wujiagang/158/2009 presented the mildest clinical symptoms. We have also discovered that disease severity (by clinical illness and histopathology) correlated with influenza specific antibody response but not viral replication in the upper respiratory tract. H1N1pdm induced the highest and most rapid antibody response followed by seasonal A/H3N2, seasonal A/H1N1 and seasonal influenza B (with B/Hubei-Wujiagang/158/2009 inducing the weakest response). Our study is the first to compare the clinical features of multiple circulating influenza strains in ferrets. These findings will help to characterize the clinical pictures of specific influenza strains as well as give insights into the development and administration of appropriate influenza therapeutics

Tai-Chi for Residential Patients with Schizophrenia on Movement Coordination, Negative Symptoms, and Functioning: A Pilot Randomized Controlled Trial

Objective. Patients with schizophrenia residing at institutions often suffer from negative symptoms, motor, and functional impairments more severe than their noninstitutionalized counterparts. Tai-chi emphasizes body relaxation, alertness, and movement coordination with benefits to balance, focus, and stress relief. This pilot study explored the efficacy of Tai-chi on movement coordination, negative symptoms, and functioning disabilities towards schizophrenia. Methods. A randomized waitlist control design was adopted, where participants were randomized to receive either the 6-week Tai-chi program and standard residential care or only the latter. 30 Chinese patients with schizophrenia were recruited from a rehabilitation residency. All were assessed on movement coordination, negative symptoms, and functional disabilities at baseline, following intervention and 6 weeks after intervention. Results. Tai-chi buffered from deteriorations in movement coordination and interpersonal functioning, the latter with sustained effectiveness 6 weeks after the class was ended. Controls showed marked deteriorations in those areas. The Tai-chi group also experienced fewer disruptions to life activities at the 6-week maintenance. There was no significant improvement in negative symptoms after Tai-chi. Conclusions. This study demonstrated encouraging benefits of Tai-chi in preventing deteriorations in movement coordination and interpersonal functioning for residential patients with schizophrenia. The ease of implementation facilitates promotion at institutional psychiatric services

Liver transplantation for acute-on-chronic liver failure

Purpose: To evaluate the outcome of liver transplantation for acute-on-chronic liver failure. Patients and methods: From November 1991 to December 2007, 517 patients underwent liver transplantation at Queen Mary Hospital, Hong Kong. Among them, 149 had acute-on-chronic liver failure as defined in the recent Asian Pacific Association for the Study of Liver Consensus Meeting. Their clinical data were reviewed and their survival outcomes were compared with those of patients who underwent liver transplantation for fulminant hepatic failure and for cirrhosis only in the same period. Results: The patients with acute-on-chronic liver failure included 50 patients having acute exacerbation of chronic hepatitis B and 99 cirrhotic patients with acute deterioration. Their median model for end-stage liver disease scores were 35 and 37, respectively. Preoperative infection (35%), hepatorenal syndrome (38%), and respiratory failure (28.8%) were common. One hundred and three patients received living donor liver grafts and 46 patients received deceased donor liver grafts. The hospital mortality rate was 4.7%. The 5-year survival rates were 93.2% for patients with acute exacerbation of chronic hepatitis B and 90.5% for cirrhotic patients with acute deterioration. The results were similar to those of the patients with fulminant hepatic failure (n = 37) and the patients having cirrhosis only (n = 301). Conclusions: Liver transplantation for acute-on-chronic liver failure is life-saving, and the survival rates it attains are similar to those attained by transplantation for other liver conditions.published_or_final_versionSpringer Open Choice, 21 Feb 201

Using behavioural theories to optimise shared haemodialysis care: a qualitative intervention development study of patient and professional experience

Background Patients in control of their own haemodialysis report better outcomes than those receiving professional controlled care in a hospital setting, even though home and hospital haemodialysis are largely equivalent from mechanical and physiological perspectives. Shared Haemodialysis Care (SHC) describes an initiative in which hospital haemodialysis patients are supported by dialysis staff to become as involved as they wish in their own care; and can improve patient safety, satisfaction and may reduce costs. We do not understand why interventions to support self-management in other conditions have variable effects or how to optimise the delivery of SHC. The purpose of this study was to identify perceived patient and professional (nurses and healthcare assistants) barriers to the uptake of SHC, and to use these data to identify intervention components to optimise care. Methods Individual semi-structured interviews with patients and professionals were conducted to identify barriers and facilitators. Data were coded to behavioural theory to identify solutions. A national UK learning event with multiple stakeholders (patients, carers, commissioners and professionals) explored the salience of these barriers and the acceptability of solutions. Results A complex intervention strategy was designed to optimise SHC for patients and professionals. Interviews were conducted with patients (n = 15) and professionals (n = 7) in two hospitals and three satellite units piloting SHC. Data from patient and professional interviews could be coded to behavioural theory. Analyses identified key barriers (knowledge, beliefs about capabilities, skills and environmental context and resources). An intervention strategy that focuses on providing, first, patients with information about the shared nature of care, how to read prescriptions and use machines, and second, providing professionals with skills and protected time to teach both professionals/patients, as well as providing continual review, may improve the implementation of SHC and be acceptable to stakeholders. Conclusions We have developed an intervention strategy to improve the implementation of SHC for patients and professionals. While this intervention strategy has been systematically developed using behavioural theory, it should be rigorously tested in a subsequent effectiveness evaluation study prior to implementation to ensure that shared haemodialysis care can be delivered equitably, efficiently and safely for all patients

Multiple Gene Polymorphisms in the Complement Factor H Gene Are Associated with Exudative Age-Related Macular Degeneration in Chinese

PURPOSE. Variants in the complement factor H (CFH) gene have been shown to be strongly associated with age-related macular degeneration (AMD). In this study, sequence alterations in CFH were investigated in 163 Chinese patients with exudative AMD and 155 unrelated Chinese control subjects. METHODS. All the 22 CFH exons, intron-exon boundaries, and promoter sequences were screened by polymerase chain reaction and DNA sequencing. RESULTS. Fifty-eight sequence changes, 42 of them novel, were identified. Six SNPs with an allele frequency Ͼ30% were significantly associated with exudative AMD. SNP rs3753396 was novel; the rest had been reported: rs3753394, rs551397, rs800292, rs2274700, and rs1329428. Two haplotype blocks were constructed. The TG haplotype for rs551397 and rs800292 was the major haplotype that conferred a significantly increased susceptibility to exudative AMD (P corr ϭ 0.0001, OR ϭ 1.91, 95% CI ϭ 1.36 -2.68). CONCLUSIONS. The findings support prior evidence that the CFH gene is one of the AMD-associated genes. There is a different distribution pattern of CFH variants in the Chinese compared with other populations. Individual SNP and haplotype analyses revealed that the ancient alleles at the 5Ј end of CFH contribute to an increased susceptibility to exudative AMD. (Invest Ophthalmol Vis Sci. 2008;49:3312-3317) DOI:10.1167/iovs.07-1517 A ge-related macular degeneration (AMD; MIM 603075; Mendelian Inheritance in Man) is a major cause of irreversible visual impairment and blindness in people older than 65 years in developed countries. 1,2 The occurrence of AMD is pan ethnic, and a high prevalence AMD has been reported in the elderly Chinese population. 5 Therefore, a greater understanding of the primary pathophysiology is needed to advance treatment and preventive measures. The etiology of AMD is complex and multifactorial, probably resulting from interactions between environmental and multigenetic factors. 6 Genetic association studies have revealed that single nucleotide polymorphisms (SNPs) in the complement factor H gene (CFH; MIM 134370; e.g., Tyr402His) are significantly associated with susceptibility to AMD. 25 A fine-scale linkage disequilibrium mapping of AMD in the CFH region detected a point location of a causal variant between exons 1 and 2 of CFH other than exon 9 for Tyr402His. MATERIALS AND METHODS Patients and Control Subjects 21 Also recruited and given complete ophthalmic examinations were 155 unrelated control subjects, 72 men and 83 women ranging in age at recruitment from 60 to 99 years (mean Ϯ SD, 73.1 Ϯ 6.5 years). They matched the patients by age and gender and had no sign of AMD or other eye diseases, except mild myopia or senile cataract. The study protocol was approved by the Ethics Committee on Human Research, the Chinese University of Hong Kong. All the procedures used conformed to the tenets of the Declaration of Helsinki. Informed consent was obtained from all study subjects after explanation of the nature of the study. Sample Collection, PCR Amplification, DNA Sequencing, and SNP Genotyping Venous blood was obtained from each study subject, and genomic DNA was extracted with a DNA blood kit (QIAamp; Qiagen, Hilden, Germany). The promoter sequence up to Ϫ867 upstream and all coding sequences of the CFH gene, including intron-exon boundaries, were screened for sequence alterations. Primers were generated based on the GenBank sequence of CFH (NM_000186.2; http://www.ncbi. nlm.nih.gov/Genbank; provided in the public domain by the National Center for Biotechnology Information, Bethesda, MD). PCR was performed on a thermal cycler (model 9700; Applied Biosystems, Inc. [ABI], Foster City, CA) with optimized protocols 27 Statistical Analysis Hardy-Weinberg equilibrium (HWE) for each polymorphism was tested by 2 test. Allele or genotype frequencies between cases and control subjects were compared by 2 analysis or the Fisher exact test. The odds ratios (ORs) of the alleles and haplotypes were estimated by 2 test (SPSS ver.15.0; SPSS Inc., Chicago, IL). Population attributable risk (PAR) of the risk genotype was calculated with the formula f(R Ϫ 1)/R, where f is the faction of cases with the risk genotype and R is the measure of OR 8 . A pair-wise linkage disequilibrium (LD, DЈ) estimation between polymorphisms with a minor allele frequency (MAF) Ͼ 1%, and EM-based haplotype association analysis were performed with Haploview (ver. 3.32, from http://www.broad.mit.edu/mpg/ haploview/ provided in the public domain by the Broad Institute, Massachusetts Institute of Technology, Cambridge, MA). For multiple comparison, probabilities were corrected by permutation test (iterations, 10,000). Statistical significance was defined as a corrected P (P corr ) Ͻ 0.05. RESULTS CFH Variants in the Study Subjects A total of 58 sequence variations were identified, all of which followed Hardy Weinberg Equilibrium Six of the seven common variants Six SNPs were identified in the promoter, all supported decreased susceptibility to AMD Haplotype Association Analysis LD analysis revealed extension of LD throughout the CFH gene. We included SNPs with MAF Ͼ 5% and two missense changes, rs1061170 (Tyr402His) and Val837Ile, in our haplotype association analysis. Two distinct haplotype blocks were detected The haplotypes H3 and H4, which were defined by all six AMD-associated SNPs, conferred significantly reduced or increased AMD susceptibility (H3: OR ϭ 0.56, 95% CI ϭ 0.39 -0.80; H4: OR ϭ 1.63, 95% CI ϭ 1.19 -2.23). When a G allele of rs1065489 (Asp936Glu) was included in these two haplotypes, the H5, which contained all the alleles in H3, remain significantly associated with the disease (P corr ϭ 0.0012). However, when a G allele or a T allele was added to the H4, the newly constructed H6 and H7 were no longer AMD associated (P corr ϭ 0.052 and 0.177, respectively). We constructed two-allele haplotypes by using rs800292 (Val62Ile) with the uncommon SNPs rs1061170 (Tyr402His) and Val837Ile, to investigate the effects of the minor variants. H10 and H11, containing a T allele of rs1061170 (Tyr402His), remained significantly associated with AMD. However, the haplotypes containing a C allele of rs1061170 DISCUSSION Although the pathogenesis of exudative AMD has not been definitively elucidated, studies in the past few years have revealed important information on its genetic basis. Polymorphisms in the CFH gene have been shown to be AMD associated in different ethnic groups, although there are obvious differences in the occurrence of disease-susceptible SNPs between Caucasian and Oriental populations. 26 mapped a point location for a causal variant between exons 1 and 2, which approximates block 1 in our present study, suggesting that the 5Ј region of the CFH (N-terminal of factor H) is commonly associated with AMD in both Chinese and Caucasians. We found haplotype block 2 spanning a region from exon 10 to intron 15 and containing SNP rs2274700 (Ala473Ala, exon 10), which have recently been shown to have a strong association with AMD in Caucasians and Japanese. Besides the haplotypes in the two haplotype blocks, the haplotypes defined by the six common SNPs (H3, H4) were also significantly associated with exudative AMD. However, when Asp936Glu (in exon 18) was included in the at-risk haplotype H4 for association analysis, the haplotypes H6 and H7, including a G or a T allele respectively, were no longer significantly associated with the disease (P corr Ͼ 0.05). Thus, Asp936Glu is less likely to be a risk factor for exudative AMD in Chinese individuals, indicating the C-terminal of the factor H contributes less than other parts of the polypeptide to the development of exudative AMD. This observation is consistent with the findings of Hageman et al

Wild Type and Mutant 2009 Pandemic Influenza A (H1N1) Viruses Cause More Severe Disease and Higher Mortality in Pregnant BALB/c Mice

BACKGROUND: Pregnant women infected by the pandemic influenza A (H1N1) 2009 virus had more severe disease and higher mortality but its pathogenesis is still unclear. PRINCIPAL FINDINGS: We showed that higher mortality, more severe pneumonitis, higher pulmonary viral load, lower peripheral blood T lymphocytes and antibody responses, higher levels of proinflammatory cytokines and chemokines, and worse fetal development occurred in pregnant mice than non-pregnant controls infected by either wild type (clinical isolate) or mouse-adapted mutant virus with D222G substitution in hemagglutinin. These disease-associated changes and the lower respiratory tract involvement were worse in pregnant mice challenged by mutant virus. Though human placental origin JEG-3 cell line could be infected and proinflammatory cytokines or chemokines were elevated in amniotic fluid of some mice, no placental or fetal involvement by virus were detected by culture, real-time reverse transcription polymerase chain reaction or histopathological changes. Dual immunofluorescent staining of viral nucleoprotein and type II alveolar cell marker SP-C protein suggested that the majority of infected alveolar epithelial cells were type II pneumocytes. CONCLUSION: The adverse effect of this pandemic virus on maternal and fetal outcome is largely related to the severe pulmonary disease and the indirect effect of inflammatory cytokine spillover into the systemic circulation