Multiple scattering of light in discrete random media using incoherent interactions.

We consider the scattering and absorption of light in discrete random media of densely packed spherical particles. In what we term "radiative transfer with reciprocal transactions" (R2T2), we introduce a volume element of the random medium, derive its scattering and absorption characteristics using the superposition T-Matrix method (STMM), and compute its frequency-domain incoherent volume-element scattering characteristics. Using an order-of-scattering approach, we then compute a numerical Monte Carlo solution for the scattering problem with an exact treatment of the interaction between two volume elements. We compute both the direct and reciprocal contributions along a sequence of volume elements, allowing us to evaluate the coherent backscattering effects. We show that the R2T2 and exact STMM solutions are in mutual agreement for large finite systems of densely packed spherical particles. We conclude that the R2T2 method provides a viable numerical solution for scattering by asymptotically infinite systems of particles.

Radiative transfer with reciprocal transactions: Numerical method and its implementation.

We present a numerical method for solving electromagnetic scattering by dense discrete random media entitled radiative transfer with reciprocal transactions (R2T2). The R2T2 is a combination of the Monte Carlo radiative-transfer, coherent-backscattering, and superposition T-matrix methods. The applicability of the radiative transfer is extended to dense random media by incorporating incoherent volume elements containing multiple particles. We analyze the R2T2 by comparing the results with the asymptotically exact superposition T-matrix method, and show that the R2T2 removes the caveats of radiative-transfer methods by comparing it to the RT-CB. We study various implementation choices that result in an accurate and efficient numerical algorithm. In particular, we focus on the properties of the incoherent volume elements and their effects on the final solution.

Scattering And Absorption of Light in Planetary Regoliths.

Theoretical, numerical, and experimental methods are presented for multiple scattering of light in macroscopic discrete random media of densely-packed microscopic particles. The theoretical and numerical methods constitute a framework of Radiative Transfer with Reciprocal Transactions (R2T2). The R2T2 framework entails Monte Carlo order-of-scattering tracing of interactions in the frequency space, assuming that the fundamental scatterers and absorbers are wavelength-scale volume elements composed of large numbers of randomly distributed particles. The discrete random media are fully packed with the volume elements. For spherical and nonspherical particles, the interactions within the volume elements are computed exactly using the Superposition T-Matrix Method (STMM) and the Volume Integral Equation Method (VIEM), respectively. For both particle types, the interactions between different volume elements are computed exactly using the STMM. As the tracing takes place within the discrete random media, incoherent electromagnetic fields are utilized, that is, the coherent field of the volume elements is removed from the interactions. The experimental methods are based on acoustic levitation of the samples for non-contact, non-destructive scattering measurements. The levitation entails full ultrasonic control of the sample position and orientation, that is, six degrees of freedom. The light source is a laser-driven white-light source with a monochromator and polarizer. The detector is a mini-photomultiplier tube on a rotating wheel, equipped with polarizers. The R2T2 is validated using measurements for a mm-scale spherical sample of densely-packed spherical silica particles. After validation, the methods are applied to interpret astronomical observations for asteroid (4) Vesta and comet 67P/Churyumov-Gerasimenko (Figure 1) recently visited by the NASA Dawn mission and the ESA Rosetta mission, respectively.

How well does a national newspaper reporting system profile drowning?

In Finland, the Finnish Association for Swimming Instruction and Life Saving (SUH) and Statistics Finland (SF) both provide nationwide data on unintentional drowning. The SUH database relies on rapid reporting from a newspaper clipping service and additional local police information, whereas the SF database relies on the later release of the death certificate information, which is based on extensive medico-legal investigation. The aim of the study was to explore the main differences between the SUH and SF databases for drowning and to evaluate the capacity of the former to characterize drowning events in Finland from 1998 to 2000. Computerized files of death certificates tabulated by SF were linked with the SUH database by deterministic methods. SF and SUH databases allowed the identification of 704 and 567 unintentional drownings, respectively, giving an unintentional drowning rate of 4.5 and 3.6/100?000 per year. Of the 704 drownings described by SF, 418 (59.4%) were also found in the SUH database. The SUH database markedly underreported drowning fatalities in certain settings, such as bath, ditch and swimming pool drownings; fall- and land-traffic-related drownings; and drownings occurring in South Finland. The narrative text of SUH drownings contributed limited information to characterize the drowning events. It was concluded that the newspaper-based SUH data provide more timely data on individual drownings but are not representative of all drownings. Conversely, the SF vital statistics data are more accurate but may take up to 2 years to become available. Both SUH and SF data provide little detailed information on drowning events. A multidisciplinary national surveillance system for drowning is necessary to provide more accurate and timely drowning data, analyse risk factors and design follow-up studies for developing and monitoring prevention strategies.

Variation in the alpha2B-adrenoceptor gene as a risk factor for prehospital fatal myocardial infarction and sudden cardiac death.

OBJECTIVES: Our aim was to corroborate the observed association between the deletion/deletion (DD) genotype of the insertion/deletion polymorphism in the alpha(2B)-adrenoceptor (AR) and increased risk for acute myocardial infarction (AMI), and to study whether this genotype also confers an increased risk for sudden cardiac death (SCD). BACKGROUND: Vasospasm has been suggested to play a role in AMI. Alpha(2)-AR mediate coronary vasoconstriction in humans, and studies on mice suggest the involvement of the alpha(2)-AR subtype B in vasoconstriction. A deletion variant of the human alpha(2B)-AR has been associated with impaired receptor desensitization in vitro. In a population-based prospective study of 912 middle-aged men, the DD genotype of the alpha(2B)-AR conferred an increased risk for AMI. METHODS: A series of 700 unselected sudden out-of-hospital deaths of middle-aged white men subjected to medico-legal autopsy was analyzed. RESULTS: Genotype information was obtained for 683 men (DD = 22%, insertion/deletion = 51%, insertion/insertion = 27%). Carriers of the DD genotype had an increased risk for SCD (n = 278, odds ratio [OR] = 2.0, p = 0.01) and fatal AMI (n = 84, OR = 2.1, p = 0.04) compared with the other two genotypes combined. The risks for SCD and fatal AMI were higher in carriers of the DD genotype who died before the age of 55 years (OR = 4.5 and 5.0, p < 0.001 for both). CONCLUSIONS: Middle-aged white men carrying the DD genotype of the alpha(2B)-AR have a significantly increased risk for SCD and AMI, especially before the age of 55 years.

Matrix metalloproteinase3 and 9 gene promoter polymorphisms: joint action of two loci as a risk factor for coronary artery complicated plaques.

OBJECTIVE: Matrix metalloproteinases 3 and 9 (MMP3 and MMP9) are present in atherosclerotic plaques and co-operate in the degradation of the fibrous cap of the atheroma, leading to fissuring and ultimately to acute coronary thrombosis. The functional genetic polymorphisms in the promoters of MMP3 and MMP9, which lead to low- and high-transcription activity genotypes, have been shown to be associated with myocardial infarction and angiographically measured atherosclerosis individually, whereas their effects in combination are not yet known. In order to assess the two disease loci simultaneously, we investigated the association of combined low and high promoter activity genotypes with different types of coronary lesions in an autopsy cohort of 300 Caucasian males aged 33-69 years (Helsinki Sudden Death Study). METHODS: Genotyping at these loci was performed by PCR, restriction enzyme digestion and minisequencing, and areas of the coronary wall covered with atherosclerotic lesions were measured using computer-assisted morphometry. RESULTS: In analysis of covariance (ANCOVA) with age, body mass index, hypertension, diabetes, smoking and alcohol consumption as covariates, a significant interaction between the MMP3 and MMP9 genotypes was observed on area of complicated lesions (P=0.012). Men with high promoter activity genotypes for both loci had, on average, more than two times larger area of complicated lesions (250%) compared with those men who had low promoter activity genotypes (P=0.008), but these loci showed no association with myocardial infarction. CONCLUSIONS: The joint action of two susceptibility loci, rather than single MMP genes alone, and the particular combination of MMP3 and MMP9 genotypes present at these loci may contribute to heterogeneity in the presentation of atherosclerosis.

Association of the endothelial nitric oxide synthase gene polymorphism with risk of coronary artery disease and myocardial infarction in middle-aged men.

Nitric oxide (NO), formed by endothelial constitutive nitric oxide synthase (eNOS) maintains endothelium-dependent vasodilatation and also mediates antithrombotic actions. The eNOS gene harbours a common polymorphism in intron 4 (4a/b), and some clinical studies have suggested an association of the rare a-allele with coronary artery disease (CAD) and myocardial infarction (MI). However, contradictory results have also been reported. We studied associations of eNOS polymorphism with CAD and MI in two prospective autopsy series comprising altogether 700 Caucasian Finnish men, who died suddenly. In ANCOVA, no significant differences in areas of atherosclerotic lesions and coronary stenosis percentages were found between men carrying the a-allele (ba+aa) compared with those homozygous for the b-allele. Subjects with the a-allele had significantly lower risk of MI (odds ratio 0.44, 95% confidence interval 0.25-0.77, P=0.004) compared with those carrying the bb genotype. Men with the a-allele also tended to have coronary thrombosis less often (odds ratio 0.43, 95% confidence interval 0.18-1.01, P=0.055). The eNOS gene 4a/b polymorphism was not associated with the extent of coronary atherosclerosis, but the a-allele of the variant seems to protect to some degree against the development of MI.

Coronary artery wall atherosclerosis in relation to the estrogen receptor 1 gene polymorphism: an autopsy study.

Estrogen receptors (ESR) 1 and 2 are expressed in the normal and atherosclerotic arteries mediating the atheroprotective action of estrogen to artery wall cells. Whether variants of these receptor genes associate with autopsy-verified coronary artery wall atherosclerosis is not known. This study investigated whether variants of the ESR1 gene are associated with autopsy-verified coronary artery wall atherosclerosis and thrombosis. Coronary arteries were taken from 300 white Finnish male autopsy cases aged 33-69 years included in the Helsinki Sudden Death Study. Areas of coronary wall covered with fatty streaks, fibrotic, calcified, and complicated lesions were measured using computer-assisted planimetry and related to ESR1 PvuII genotypes (P/P, P/p, and p/p) determined by PCR. The mean area of complicated lesions of three major coronaries and the presence of coronary thrombosis were significantly associated with the ESR1 genotype in men aged 53 years or older (median age as a cut off point). No such association was found in men aged under 53 years. After adjusting for age and body mass index the men aged 53 years or over with P/p and P/P genotype had areas of complicated lesions on average two- and fivefold larger than subjects with the p/p genotype. The age and body mass index adjusted odds ratios for coronary thrombosis were 6.2 for P/p and 10.6 for P/P compared to men with the p/p genotype. After additional adjustment for diabetes and hypertension the ESR1 genotype persisted as an independent predictor of complicated lesions ( P=0.007) and coronary thrombosis. In conclusion, the ESR1 gene is a potential candidate behind the pathogenesis of acute coronary events.

Association of paraoxonase-1 M55L genotype and alcohol consumption with coronary atherosclerosis: the Helsinki Sudden Death Study.

High-density lipoprotein (HDL) level is inversely correlated with coronary heart disease risk. Paraoxonase-1 (PON1) is an HDL-associated anti-atherogenic enzyme. The activity of PON1 is affected by the methionine for leucine substitution at position 55 (M55L) and increased during regular moderate alcohol consumption, consistent with increased HDL cholesterol concentration. We related the PON1 M55L genotypes to the extent of atherosclerosis in left anterior descending coronary artery (LAD) in alcohol abstainers (0-1 g of alcohol/day), moderate consumers (1-36 g of alcohol/day) and drinkers (> 36 g of alcohol/day). The study subjects included an autopsy series of total of 700 middle-aged Finnish men from the Helsinki Sudden Death Study. The LAD was stained for fat and the areas covered with fatty streaks and fibrotic and complicated plaques were measured. Data on coronary artery disease risk factors were obtained from relatives or close friends of the deceased. Compared to the LL homozygotes, carriers of the M55 allele tended to have larger areas of atherosclerotic lesions, the size of which decreased dose-dependently by reported alcohol consumption. Moderate consumers carrying the M55 allele had significantly larger complicated plaques compared to the LL homozygotes drinking as much (P = 0.009). Among the M55 allele carriers, drinkers showed significantly smaller areas of fatty streaks compared to abstainers (P = 0.042) and moderate consumers (P < 0.001) (for the PON1 genotype by alcohol interaction, P = 0.078). Similarly, drinkers with the M55 allele also had statistically significantly smaller areas of complicated lesions than moderate consumers with the M55 allele (P < 0.0001) (for the PON1 genotype by alcohol interaction, P = 0.009). The areas of atherosclerotic lesions in LAD appear to be dependent on the amount of alcohol consumption, especially in men carrying the PON1 M55 allele.

Platelet membrane collagen receptor glycoprotein VI polymorphism is associated with coronary thrombosis and fatal myocardial infarction in middle-aged men.

Glycoprotein VI is a platelet collagen receptor binding to subendothelial collagen after a rupture of an atherosclerotic plaque. The GPVI gene is polymorphic with several SNPs and the T13254C polymorphism predicting amino acid substitution (serine to proline) has been associated with the risk of MI in a preliminary study. We studied the association of the GPVI T13254C with fatal myocardial infarction (MI) and coronary artery disease among the 300 men of the Helsinki Sudden Death Study (HSDS). Genotype frequencies were 77.9% for TT, 20.7% for CT and 1.4% for CC. We found a significant association (P = 0.02) between the C-allele carriers (CT or CC) and coronary thrombosis (OR 2.5, 95% CI: 1.05-6.2). There was also a tendency (P = 0.07) for an association between the C-allele and acute myocardial infarction (AMI) (OR 2.2). The average area of complicated coronary lesions was also significantly (P = 0.01) larger in carriers compared to non-carriers of the C-allele. Our findings support previous results on the role of this GPVI polymorphism, or another linked polymorphism, as a possible predictor of the risk of coronary thrombosis.

Platelet collagen receptor GPIa (C807T/HPA-5) haplotype is not associated with an increased risk of fatal coronary events in middle-aged men.

Platelet GPIa/IIa receptors play key roles in the adhesion of platelets to collagen during the formation of coronary thrombosis. The C807T and HPA-5 polymorphisms of the gene for GPIa define three distinct alleles of GPIa which are associated with the surface expression of the protein in an allele-dependent fashion. Significance of these polymorphisms in victims of sudden cardiac death (SCD) was studied in Helsinki Sudden Death Study (HSDS) comprising 700 autopsied middle-aged Caucasian Finnish men with 288 SCD victims and 84 men with fatal acute myocardial infarction (AMI). The high-expression A1 allele was found in 36.6% of control men as opposed to 38.0% of all SCD victims and 36.9% of men with fatal AMI (P>0.4). The high-expression A1A1 genotype was found in 11.9% of men with fatal AMI and 10.0% of controls as opposed to the low-expression A2A2 genotype which was found in 29.8% of men with fatal AMI and in 31.2% of controls (OR 1.2, P>0.3). Age group (under/over 55) had no effect on the results. Our results do not support an effect of the GPIa haplotype on fatal coronary events among middle-aged men.

Smoking-dependent association between paraoxonase 1 M/L55 genotype and coronary atherosclerosis in males: an autopsy study.

High-density lipoprotein-associated paraoxonase 1 (PON1) enzyme can retard the oxidation of lipids. The methionine for leucine substitution at position 55 (M/L55) of the PON1 protein is associated with lower (MM genotype) or higher (ML or LL genotype) expression of the gene affecting serum level of PON1. We studied the association of the PON1 M/L55 genotype with the extent of atherosclerosis in an autopsy series of Finnish males. Areas of the coronary arteries and the aorta covered with fatty streaks and fibrotic and complicated lesions were measured from a total of 700 cases. Carriers of the MM genotype (14.4% of subjects) had larger percentual areas of fatty streaks in their left anterior descending coronary artery (P=0.014) and right coronary artery (P=0.004), as well as in thoracic (P<0.001) and abdominal aorta (P=0.010) compared to carriers of the LL or ML genotype. A PON1 genotype-by-smoking interaction was observed on the area of fatty streaks in left anterior descending coronary artery (P=0.011) and right coronary artery (P=0.005); the association between fatty streaks and MM genotype was evident only among non-smokers, whereas in smokers this association was abolished. The areas of more advanced atherosclerotic lesions did not vary significantly between the genotype groups. These data suggest that the genetic variation of PON1 affects the formation of early atherosclerotic lesions and that the effect is modified by smoking.

Coronary artery calcification is related to functional polymorphism of matrix metalloproteinase 3: the Helsinki Sudden Death Study.

Matrix metalloproteinase 3 (MMP3) is expressed in human coronary atherosclerotic lesions and is known to be involved in degradation of the plaque and to be co-localized with calcium and fibrin deposits in advanced lesions, indicating a possible role of MMP3 in arterial calcification. The MMP3 gene promoter polymorphism leads to low promoter activity 6A6A, intermediate promoter activity 5A6A and high promoter activity 5A5A genotypes. To determine whether these genotypes predict the extent of atherosclerosis we investigated their association with different types of coronary lesions in an autopsy series of 300 middle-aged white Finnish men (aged 35-69 years) from the Helsinki Sudden Death Study (HSDS). Areas of the coronary wall covered with different atherosclerotic lesions were measured and MMP3 genotypes were determined by PCR and minisequencing. In men >/=53 years the mean area of calcified lesion in the most severely affected coronary artery was significantly associated with the MMP3 genotype (P=0.029). Subjects with high promoter activity genotypes had on average larger calcified lesion areas than those with the low-activity genotype. The MMP3 genotype (P=0.025) persisted as an independent predictor of mean calcified lesion area after stepwise adjustment for age, BMI, hypertension, diabetes, number of affected vessels and smoking. These data provide evidence that the proposed effect of MMP3 in the process of atherogenesis may be modified by the MMP3 genotype.

Unintentional drowning in Finland 1970-2000: a population-based study.

BACKGROUND: While standard data on drowning reported by the World Health Organization (WHO) fails to provide a reliable picture of the burden of drowning in Finland, they suggest that the rates are much higher than those of other industrialized countries. AIM: To determine the true burden of drowning in Finland and factors related to its high rates. DESIGN: Descriptive, retrospective, population-based analysis of all deaths by drowning, among residents of all ages. SETTING: Finland, 1970-2000. MATERIAL AND METHODS: Mortality and population data furnished by Statistics Finland (SF) were used to determine age- and sex-specific drowning mortality rates using both nature- and cause-of-injury codes. Individual-level data from the death certificates were analysed and cross-linked to a nationwide postmortem toxicology database. RESULTS: From 1970 to 2000, 9279 unintentional drownings occurred (mean: 299.3/year SD 84.3, rate 6.1/100 000/year; M:F ratio = 8.6:1), accounting for 11.7% of all unintentional injury deaths. Drowning rates overall have decreased from 9.9/100 000/year in 1970-1972, to 4.5 in 1998-2000 (-2.7%/year; 95% CL: -3.0; -2.5). The most frequent activities related to drowning included boating (29.8%), falling (26.1%), swimming (25.0%), and activities on ice (12.4%). In non-boating-related drownings, 74.5% of males and 67.4% of females tested had a blood alcohol concentration (BAC) >/=50 mg/dl, while in boating-related drownings, the respective values were 78.1% and 71.4%. CONCLUSIONS: WHO statistics underestimate the true burden of drowning in Finland by up to 40-50%. Drowning rates and alcohol involvement in drowning are much higher than in other comparable developed countries. Broad-based countermeasures to reduce alcohol use in water activities are needed as part of any strategy to reduce drowning rates.

Amniotic fluid embolism as cause of death in a car accident--a case report.

Amniotic fluid embolism (AFE), a relatively rare complication in pregnancy, has a high mortality rate. We describe a case of a 38-week pregnant woman with such an embolism leading to almost immediate death after a blunt abdominal trauma inflicted in a motor vehicle accident and probably associated with improper positioning of a seat belt. It has been assumed that the pathophysiology of amniotic fluid embolism is related to an anaphylactoid reaction and that mast cell degranulation indicates this mechanism. Moreover, immunohistochemical antitryptase staining of pulmonary tissue samples in our case revealed mast cell degranulation.

Reliability and validity of eight dental age estimation methods for adults.

This paper evaluates the reliability and validity of eight published dental age estimation methods for adults that may aid in victim identification. Age was calculated on 20 Caucasian teeth of known age according to the methods of Kvaal (for in situ and extracted teeth), Solheim (for in situ and sectioned teeth), Lamendin (for extracted teeth), Johanson (for sectioned teeth) and Bang (for extracted and sectioned teeth) by one independent observer. For each method, mean age error and standard error were assessed as the measures of accuracy and precision. In addition, method simplicity, requirements for tooth preparation and the equipment necessary were assessed and recommendations given for forensic use in various situations. Methods for sectioned teeth gave more reliable results when compared to methods for intact teeth.

Dentists' qualifications affect the accuracy of radiographic identification.

This study assessed the effects of forensic odontologists' training and experience upon the accuracy of their dental radiographic identifications. Forty participating odontologists with various levels of training and experience completed a Web-based survey of their qualifications and then completed nine Web-based radiographic identification cases. They made their identifications using the American Board of Forensic Odontology Categories and Terminology for Body Identification. The results indicate that odontologists with high levels of training and experience performed significantly more accurately than those with lower levels. We conclude that high levels of training and experience in forensic odontology should be developed, maintained, and required of dentists who participate in a forensic team dealing with challenging identification cases.

Undetermined drowning.

Drowning is one of the leading causes of death when the manner of death remains undetermined. In the present study, we examined the epidemiological and medico-legal profile of 276 undetermined deaths (M:F=3.4:1; mean age 41.9+/-16.0 SD) among 1,707 consecutive bodies found in water and autopsied at the Department of Forensic Medicine, University of Helsinki, from 1976 to 2000. We also describe the differences between the police investigator's initial opinion and the forensic pathologist's death certification, and the different approaches among forensic pathologists when determining the cause of death. There was considerable variation among individual pathologists in the percentage of deaths considered undetermined but these differences were not significantly related to their level of training. Medico-legal training should focus on a standardised diagnostic approach to borderline cases, in which essential factors in determining the manner of death are often ambiguous.

Analysis of the adequate size of a cord blood bank and comparison of HLA haplotype distributions between four populations.

The number of units and especially the number of different HLA haplotypes present in a cord blood (CB) bank is a crucial determinant of its usefulness. We generated data relevant to the development of our national CB in Finland. The HLA haplotype distribution was examined between specific populations. We developed graphical ways of data presentation that enable easy visualization of differences. First, we estimated the optimal size of a CB bank for Finland and found that approximately 1700 units are needed to provide a 5/6 HLA-matched donor for 80% of Finnish patients. Secondly, we evaluated HLA haplotype distributions between four locations, Finland, Japan, Sweden and Belgium. Our results showed that the Japanese Tokyo Cord Blood Bank differs in both the frequency and distribution of haplotypes from the European banks. The European banks (Finnish Cord Blood Registry, The Swedish National Cord Blood Bank, and Marrow Donor Program-Belgium) have similar frequencies of common haplotypes, but 26% of the haplotypes in the Finnish CB bank are unique, which justifies the existence of a national bank. The tendency to a homogenous HLA haplotype distribution in banks underlines the need for targeting recruitment at the poorly represented minority populations.