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Biomedical subjects

S L Lau

Publications and source records attributed to S L Lau.

8 recordsLinked to original sources
PubMed2006

Levels of evidence and journal impact factor in oral and maxillofacial surgery.

The aim of this study was to identify the relationship between quality of research, in terms of levels of evidence, and journal impact factor (IF), and to describe the pattern of publications in oral and maxillofacial surgery. All four major journals in this subject area only, and with a published IF, were included in the study. Latest published IF dated 2004 was chosen, and all articles related to its calculation were accessed and classified into four levels of evidence. Correlation between levels of evidence and IF was investigated and the pattern of publications was described. All eligible 932 published articles were analysed. None (0%) were level I evidence, 20 (2%) were Level II, 70 (8%) level III and 337 (40%) level IV; 465 (50%) articles were classified as non-evidence. IF ranged from 0.689 to 1.154. There were statistically significant correlations between levels of evidence and IF (rho=1.0, P<0.01). Among the 465 non-evidence articles, there were 219 (47%) case reports, 91 (20%) animal studies, 52 (11%) laboratory studies, 35 (8%) technical notes, 24 (5%) tutorial articles, and 16 (3%) reviews articles.

Bibliometrics↗
PubMed2006

Recurrence related to treatment modalities of unicystic ameloblastoma: a systematic review.

This systematic review aims to identify all studies pertinent to the clinical question, 'which treatment for unicystic ameloblastoma results in the lowest recurrence rate?' A structured systematic search of the literature, with predefined inclusion and exclusion criteria, using computer and manual searches as well as personal communication, was performed. Evaluations and critical appraisal were done separately in 3 rounds. All searches were performed by 2 independent judges and any disagreement was settled by discussion with a third party. Four treatment modalities for unicystic ameloblastomas were identified. The recurrence rates were 3.6% for resection, 30.5% for enucleation alone, 16% for enucleation followed by application of Carnoy's solution and 18% for marsupialization with/without other treatment in a second phase. It was concluded that there is only weak evidence showing that jaw resection resulted in the lowest recurrence rate, followed by enucleation with application of Carnoy's solution. Enucleation alone resulted in the highest recurrence rate and treatment by marsupialization cannot be sufficiently evaluated since most cases were followed by a second stage surgery of some kind.

Acetic Acid↗
PubMed2006

Correlation analysis among highway stormwater pollutants and characteristics.

Stormwater runoff from highway land use is a common non-point source of pollutants. A large quantity of highway stormwater runoff characteristics were collected in California during the past three years. Correlations among various water quality parameters and constituents were performed using data sets collected over the 2000-2001, 2001-2002, and 2002-2003 wet seasons for 18, 21 and 23 storm events at three highway sites in west Los Angeles, California. In addition, statistical and graphical correlation analysis of the mass first flush ratio (MFF) with storm characteristics was made to determine if the first flush is related to site or storm characteristics. The results and analyses performed indicate that (1) TSS correlates well with most particulate-bound metals. However, TSS was poorly correlated with most other pollutants. (2) Strong correlations were also observed among dissolved and total metals; DOC, COD, TKN and oil and grease; conductivity and Cl. (3) Total metals, COD and DOC were generally well correlated with mass first flush, suggesting that BMPs that treat the early portion of runoff have an opportunity to remove high concentrations of these pollutants.

Air Pollutants↗
PubMed2005

A new modeling approach for estimating first flush metal mass loading.

The purpose of this study was to investigate pollutant mass loading from major highways in Southern California, with emphasis on interpretation of event mean concentrations and first flush effects. The results of monitoring eight sites during the 1999-2002 storm seasons found that metal contaminants had higher concentrations at the early stages of storm events compared with other stages of rain storms. A new washoff model was developed to predict the event mean concentrations of metal contaminants taking first flush effect into account. Model variable parameters included average daily traffic, antecedent dry period, rain intensity, total runoff volume, and runoff coefficient. The results obtained using the washoff model were compared with measured values and found to fit well for heavy metals with R2 ranging from 0.8 to 0.95.

California↗
PubMed2001

Catch basin inserts to reduce pollution from stormwater.

Stormwater contamination represents the largest source of contaminants to many receiving waters in the United States, such as Santa Monica Bay in Los Angeles, California. Point sources to these same waters generally receive secondary or better treatment before they are released, and they are usually discharged through outfalls that diffuse the wastewater plume to prevent it from contacting the shoreline. Stormwaters receive no treatment and reach the receiving waters through a variety of ways, but most enter through catch basins or inserts to storm drains that terminate at the beach or in shallow coastal areas. Under these conditions, the stormwater discharge may have greater impact on the quality and utility of the receiving water than the treated wastewater discharges. One method of reducing pollution is to equip catch basins with an insert that can capture pollutants. A number of commercially available devices exist but few have been evaluated by independent parties in full-scale applications. A series of tests using bench and full-scale devices under both laboratory and field conditions were conducted to evaluate their ability to remove trash and debris, suspended solids and oil and grease in stormwaters. The results presented in the paper should provide a basis for future insert development and application.

Cities↗
PubMed1997

Marr's theory of the neocortex as a self-organizing neural network.

Marr's proposal for the functioning of the neocortex (Marr, 1970) is the least known of his various theories for specific neural circuitries. He suggested that the neocortex learns by self-organization to extract the structure from the patterns of activity incident upon it. He proposed a feedforward neural network in which the connections to the output cells (identified with the pyramidal cells of the neocortex) are modified by a mechanism of competitive learning. It was intended that each output cell comes to be selective for the input patterns from a different class and is able to respond to new patterns from the same class that have not been seen before. The learning rule that Marr proposed was underspecified, but a logical extension of the basic idea results in a synaptic learning rule in which the total amount of synaptic strength of the connections from each input ("presynaptic") cell is kept at a constant level. In contrast, conventional competitive learning involves rules of the "postsynaptic" type. The network learns by exploiting the structure that Marr assumed to exist within the ensemble of input patterns. For this case, analysis is possible that extends that carried out by Marr, which was restricted to the binary classification task. This analysis is presented here, together with results from computer simulations of different types of competitive learning mechanisms. The presynaptic mechanism is best known in the computational neuroscience literature. In neural network applications, it may be a more suitable mechanism of competitive learning than those normally considered.

Algorithms↗
PubMed1991

Neurobehavioral effects of the on-call experience in housestaff physicians.

Sixty-tree medical residents were tested on a battery of computer-based, self-administered neurobehavioral tests before and after a 36-hour in-hospital call plus postcall day to assess the central nervous system effects of the call experience and its accompanying sleep deprivation. Statistically significant decreases in performance were found postcall on tests of sustained visual attention (P less than 0.0001), speed and coding ability (P less than 0.0001) and short-term recall (P less than 0.0001). Hand-eye coordination improved (P less than 0.02).

Humans↗