A geometric-process maintenance model for a deteriorating system under a random environment

This paper studies a geometric-process maintenance-model for a deteriorating system under a random environment. Assume that the number of random shocks, up to time t, produced by the random environment forms a counting process. Whenever a random shock arrives, the system operating time is reduced. The successive reductions in the system operating time are statistically independent and identically distributed random variables. Assume that the consecutive repair times of the system after failures, form an increasing geometric process; under the condition that the system suffers no random shock, the successive operating times of the system after repairs constitute a decreasing geometric process. A replacement policy N, by which the system is replaced at the time of the failure N, is adopted. An explicit expression for the average cost rate (long-run average cost per unit time) is derived. Then, an optimal replacement policy is determined analytically. As a particular case, a compound Poisson process model is also studied.published_or_final_versio

Is effort praise motivational? The role of beliefs in the effort-ability relationship

In two studies, we investigated how beliefs in the effort-ability relationship moderated the effects of effort praise on student motivation. Study 1 showed that the more the participants believed that effort and ability were related positively (the positive rule) versus related negatively (the inverse rule), the more they would have positive self-evaluation and intrinsic motivation after effort praise. Study 2, with participants' beliefs manipulated by a priming procedure, showed that the participants in the positive rule condition had better self-evaluation and more intrinsic motivation after effort praise than their counterparts did in the inverse rule condition. The results of the two studies converged to indicate that the motivational effects of effort praise depend on beliefs in the effort-ability relationship. © 2008 Elsevier Inc. All rights reserved.postprin

Surveillance of acute flaccid paralysis in Hong Kong: 1997 to 2002

Objectives. To describe the characteristics of patients reported with acute flaccid paralysis between 1997 and 2002, and to evaluate the performance of the acute flaccid paralysis surveillance system using indicators recommended by the World Health Organization. Design. Retrospective study. Setting. Department of Health, Hong Kong. Participants. Children aged younger than 15 years who were reported to the Department of Health between 1997 and 2002 with acute flaccid paralysis. Results. Of 120 children with acute flaccid paralysis reported between 1997 and 2002, 42% were younger than 5 years of age. None of the cases were acute poliomyelitis or polio-compatible. A neurological cause was identified in 67.5% of cases, of which the most common was Guillain-Barré syndrome (42%), followed by transverse myelitis (15%). All except one of the performance indicators consistently met World Health Organization requirements and thus demonstrated the effectiveness of the acute flaccid paralysis surveillance programme. The acute flaccid paralysis notification rate consistently exceeded 1.0 per 100 000 population below 15 years of age. The requirement for adequate stool investigation was the single indicator that did not satisfy World Health Organization requirements. This highlighted the importance of maintaining physicians' awareness of acute flaccid paralysis surveillance. Conclusion. Hong Kong should remain vigilant for acute flaccid paralysis. The effective surveillance system and its evaluation may serve as a model for surveillance of other infectious diseases.published_or_final_versio

Human induced pluripotent stem cell-derived mesenchymal stem cells are superior to adult bone marrow-derived mesenchymal stem cells in the treatment of limb ischemia

Conference invited speaker: Dr. Lian, QOral Presentation: Session S31 - Genetic Determinants of Heart Disease, Gene and Cell Based Therapies, Basic Research: abstract no. 1489postprintThe 16th World Congress on Heart Disease of the International Academy of Cardiology Annual Scientific Sessions 2011, Vancouver, B.C., 23-27 July 2011

Water compatible resin for separation and recovery of dissolved precious metals

Trace Contaminants in Water: Genesis, Rapid Detection and Sustainable Removal Processes: abstract no. 353fOpen URL - http://apps.aiche.org/proceedings/Abstract.aspx?PaperID=119742The value of precious metals such as gold to be recovered in the industrial effluents within Pearl River Delta area is over HK$20 million per annual. Furthermore, with the expected tightening of environmental legislation and enforcement in the Mainland China, there is a growing need of effluent treatment technology. Traditionally, ion-exchange resin, polymer ultra-filtration and micro-emulsion are applied in the treatment of plating effluents. However, they all have different weaknesses. Many reports have been published for the separation using aqueous biphasic system. Based on this methodology, polystyrene-grafted-polyglycidol (PS-PG), a water-compatible polymer was synthesized. This type of polymer can be used for gold or silver extraction. After extraction, the recovery of metal can be achieved by direct electro-deposition or reverse extraction using sodium cyanide.postprintThe 2008 AIChE Annual Meeting (AIChE 100), Philadelphia, PA., 16-21 November 2008. In Conference Proceedings, 2008, p. 1-

Methylation of E-caderin gene in gastric cancer and in normal gastric mucosa from patients with and without Helicobacter pylori infection

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An innovation approach on the separation of metal

There has been increasing environmental concerns on the metallic pollution in recent decades. The conventional technologies used for metal extraction are ion-exchange resins, polymer ultrafiltration and microemulsion. The whole extraction mechanism can be divided into 4 steps: 1) The binding of dissolved metal to active sites, 2) Separation of the metal load extractant from the lean phase, 3) Reverse extraction of loaded metal for recovery 4) Recycling of extractant for repeated extraction. Each of the conventional methods suffers different drawbacks in different steps of the extraction mechanism….postprintThe 2008 AIChE Annual Meeting (AIChE 100), Philadelphia, PA., 16-21 November 2008. In Proceedings of the 2008 AIChE Annual Meeting, AIChE 10

Primary immunodeficiency in Hong Kong and the use of genetic analysis for diagnosis

Objectives. To review the management of primary immunodeficiency and discuss recent advances in genetic analysis. Design. Retrospective study. Setting. University teaching hospital, Hong Kong. Patients. Children diagnosed with primary immunodeficiency and followed up in the immunology clinic during the period 1988 to 2003. Main outcome measures. Demographic data, co-morbidities and treatment of patients, outcome and complications; identification of disease by genetic mutations. Results. Medical records of a total of 117 patients (72 male, 45 female) diagnosed with primary immunodeficiency in the Department of Paediatrics and Adolescent Medicine, Queen Mary Hospital, Hong Kong during the past 15 years (1988-2003) were reviewed. All patients were followed up in the immunology clinic. Some patients had been referred from the private sector or other hospitals for immunological workup. Six categories of primary immunodeficiency were identified: predominantly humoral defect (n=50), predominantly cellular defect (n=22), combined humoral and cellular defect (n=5), phagocytic defect (n=18), complement disorders (n=4), and others (n=18). Although infection was the underlying cause of most co-morbidities and mortality, autoimmune (n=7) and allergic (n=23) manifestations were common. In addition, three patients developed lymphoma. Recent advances in the genetic diagnosis of several types of primary immunodeficiency were also reviewed: X-linked Wiskott-Aldrich syndrome, X-linked chronic granulomatous disease, X-linked agammaglobulinaemia, X-linked lymphoproliferative syndrome, leukocyte adhesion disease type I, and X-linked hyperimmunoglobulin M syndrome. This provides an invaluable means of understanding the molecular basis of primary immunodeficiency and has important clinical applications. Conclusions. Co-morbidities like autoimmune disease and allergic disease are common in patients with primary immunodeficiency and should be carefully evaluated. Likewise, a diagnosis of primary immunodeficiency should be considered when evaluating patients with these conditions. Rapid progress in the field of molecular genetics will enable definite and early diagnosis, and more importantly, potential curative therapy to be administered.published_or_final_versio

Regulatory role of proheparanase with peri-synaptic heparan sulfate proteoglycan and AMPA-type glutamate receptor in synaptic plasticity

Poster Presentation: P59AMPA-type glutamate receptors (AMPAR) govern excitatory synaptic transmission. Perineuronal heparan sulfates (HS) have been implicated in controlling the open-state of AMPAR. Our finding of neuronal heparanase expression in adult rats led us to test (1) if neuronal heparanase is secreted and (2) if the secreted form acts on perineuronal HS to modulate synaptic plasticity. Neuronal secretion of heparanase was triggered by phorbol ester of rat hippocampal neurons in culture. Western blot analysis of the secreted product revealed enzymatically inactive proheparanase, but not the enzymatically active heparanase. Synaptosomes prepared from phorbol ester-treated rat cortexslices showed enrichment in proheparanase; co-immunoprecipitation studies further showed association of AMPAR subunits (GluA1 and GluA2/3) with both syndecan-3 (a transmembrane HS-proteoglycan) and proheparanase, suggesting their partnership in the peri-synaptic environment. Treatment of hippocampal neurons in culture with recombinant proheparanase triggered internalization of proheparanase, perineuronal HS-proteoglycans and AMPARs, suggesting their clustering as a functional complex. Heparitinase pre-treatment of hippocampal neuron cultures reduced proheparanase-induced internalization of AMPARs, suggesting that the HS moiety is critical for effecting the partnership. Treatment of hippocampal slices with recombinant proheparanase resulted in down-regulation of both basal synaptic strength and LTP at Schaffer collateral synapses. These results reveal a novel role of neuronal proheparanase in resetting AMPAR and perineuronal HS levels at the synapse and thus the modulation of synaptic plasticity.postprin