RHESSI and SOHO CDS Observations of Explosive Chromospheric Evaporation

Simultaneous observations of explosive chromospheric evaporation are presented using data from the Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) and the Coronal Diagnostic Spectrometer (CDS) on board the Solar and Heliospheric Observatory. For the first time, cospatial imaging and spectroscopy have been used to observe explosive evaporation within a hard X-ray emitting region. RHESSI X-ray images and spectra were used to determine the flux of nonthermal electrons accelerated during the impulsive phase of an M2.2 flare. When we assumed a thick-target model, the injected electron spectrum was found to have a spectral index of similar to 7.3, a low-energy cutoff of similar to 20 keV, and a resulting flux of >= 4 x10(10) ergs cm(-2) s(-1). The dynamic response of the atmosphere was determined using CDS spectra; we found a mean upflow velocity of 230 +/- 38 km s(-1) in Fe (XIX) (592.23 angstrom) and associated downflows of 36 +/- 16 and 43 +/- 22 km s(-1) at chromospheric and transition region temperatures, respectively, relative to an averaged quiet- Sun spectra. The errors represent a 1 j dispersion. The properties of the accelerated electron spectrum and the corresponding evaporative velocities were found to be consistent with the predictions of theory.

A new device for the study of electron-ion interactions

The conceptual design of a new electron beam ion trap primarily intended for the study of electron-ion interactions is outlined along with some preliminary predictions regarding its capabilities. (C) 2003 Elsevier Science B.V. All rights reserved.

An automated machine vision system for the histological grading of cervical intraepithelial neoplasia (CIN)

The histological grading of cervical intraepithelial neoplasia (CIN) remains subjective, resulting in inter- and intra-observer variation and poor reproducibility in the grading of cervical lesions. This study has attempted to develop an objective grading system using automated machine vision. The architectural features of cervical squamous epithelium are quantitatively analysed using a combination of computerized digital image processing and Delaunay triangulation analysis; 230 images digitally captured from cases previously classified by a gynaecological pathologist included normal cervical squamous epithelium (n = 30), koilocytosis (n = 46), CIN 1 (n = 52), CIN 2 (n = 56), and CIN 3 (n=46). Intra- and inter-observer variation had kappa values of 0.502 and 0.415, respectively. A machine vision system was developed in KS400 macro programming language to segment and mark the centres of all nuclei within the epithelium. By object-oriented analysis of image components, the positional information of nuclei was used to construct a Delaunay triangulation mesh. Each mesh was analysed to compute triangle dimensions including the mean triangle area, the mean triangle edge length, and the number of triangles per unit area, giving an individual quantitative profile of measurements for each case. Discriminant analysis of the geometric data revealed the significant discriminatory variables from which a classification score was derived. The scoring system distinguished between normal and CIN 3 in 98.7% of cases and between koilocytosis and CIN 1 in 76.5% of cases, but only 62.3% of the CIN cases were classified into the correct group, with the CIN 2 group showing the highest rate of misclassification. Graphical plots of triangulation data demonstrated the continuum of morphological change from normal squamous epithelium to the highest grade of CIN, with overlapping of the groups originally defined by the pathologists. This study shows that automated location of nuclei in cervical biopsies using computerized image analysis is possible. Analysis of positional information enables quantitative evaluation of architectural features in CIN using Delaunay triangulation meshes, which is effective in the objective classification of CIN. This demonstrates the future potential of automated machine vision systems in diagnostic histopathology. Copyright (C) 2000 John Wiley and Sons, Ltd.

A numerical approach to C-14 wiggle-match dating of organic deposits: best fits and confidence intervals

14C wiggle-match dating (WMD) of peat deposits uses the non-linear relationship between 14C age and calendar age to match the shape of a sequence of closely spaced peat 14C dates with the 14C calibration curve. A numerical approach to WMD enables the quantitative assessment of various possible wiggle-match solutions and of calendar year confidence intervals for sequences of 14C dates. We assess the assumptions, advantages, and limitations of the method. Several case-studies show that WMD results in more precise chronologies than when individual 14C dates are calibrated. WMD is most successful during periods with major excursions in the 14C calibration curve (e.g., in one case WMD could narrow down confidence intervals from 230 to 36 yr).

Relationship between Helicobacter pylori infection and gastric atrophy and the stages of the oesophageal inflammation, metaplasia, adenocarcinoma sequence: Results from the FINBAR case-control study.

Objective: A number of studies have shown an inverse association between infection with Helicobacter pylori and oesophageal adenocarcinoma (OAC). The mechanism of the apparent protection against OAC by H pylori infection and, in particular, the role of gastric atrophy is disputed. The relationship between all stages of the oesophageal inflammation, metaplasia, adenocarcinoma sequence and H pylori infection and gastric atrophy was explored. Methods: A case-control study involving 260 population controls, 227 OAC, 224 Barrett's oesophagus (BO) and 230 reflux oesophagitis (RO) patients recruited within Ireland was carried out. H pylori and CagA (cytotoxin-associated gene product A) infection was diagnosed serologically by western blot, and pepsinogen I and II levels were measured by enzyme immunoassay. Gastric atrophy was defined as a pepsinogen I/II ratio of <3. Results: H pylori seropositive was inversely associated with OAC, BO and RO; adjusted ORs (95% CIs), 0.49 (0.31 to 0.76), 0.35 (0.22 to 0.56) and 0.42 (0.27 to 0.65), respectively. Gastric atrophy was uncommon (5.3% of all subjects), but was inversely associated with non-junctional OAC, BO and RO; adjusted ORs (95% CIs), 0.34 (0.10 to 1.24), 0.23 (0.05 to 0.96) and 0.27 (0.08 to 0.88), respectively. Inverse associations between H pylori and the disease states remained in gastric atrophy-negative patients. Conclusion: H pylori infection and gastric atrophy are associated with a reduced risk of OAC, BO and RO. While use of the pepsinogen I/II ratio as a marker for gastric atrophy has limitations, these data suggest that although gastric atrophy is involved it may not fully explain the inverse associations observed with H pylori infection.

No association between hOGG1, XRCC1, and XPD polymorphisms and risk of reflux esophagitis, Barrett's Esophagus, or esophageal adenocarcinoma: Results from the factors influencing the Barrett's adenocarcinoma relationship case-control study

Reflux of gastric contents can lead to development of reflux esophagitis and Barrett's esophagus. Barrett's esophagus is a risk factor for esophageal adenocarcinoma. Damage to DNA may lead to carcinogenesis but is repaired through activation of pathways involving polymorphic enzymes, including human 8-oxoguanine glycosylase 1 (hOGG1), X-ray repair cross-complementing 1 (XRCC1), and xeroderma pigmentosum group D (XPD). Of the single nucleotide polymorphisms identified in these genes, hOGG1 Ser 326Cys, XRCC1 Arg 399Gln, and XPD Lys 751Gln are particularly common in Caucasians and have been associated with lower DNA repair capacity. Small studies have reported associations with XPD Lys 751Gln and esophageal adenocarcinoma. XRCC1 Arg 399Gln has been linked to Barrett's esophagus and reflux esophagitis. In a population-based case-control study, we examined associations of the hOGG1 Ser 326Cys, XRCC1 Arg 399Gln, and XPD Lys 751Gln polymorphisms with risk of esophageal adenocarcinoma, Barrett's esophagus, and reflux esophagitis. Genomic DNA was extracted from blood samples collected from cases of esophageal adenocarcinoma (n = 210), Barrett's esophagus (n = 212), reflux esophagitis (n = 230), and normal population controls frequency matched for age and sex (n = 248). Polymorphisms were genotyped using Taq-Man allelic discrimination assays. Odds ratios and 95% confidence intervals were obtained from logistic regression models adjusted for potential confounding factors. There were no statistically significant associations between these polymorphisms and risk of esophageal adenocarcinoma, Barrett's esophagus, or reflux esophagitis.

Cyclooxygenase-2 and inducible nitric oxide synthase gene polymorphisms and risk of reflux esophagitis, Barrett's Esophagus, and esophageal adenocarcinoma

The incidence of esophageal adenocarcinoma has increased in recent years, and Barrett's esophagus is a recognized risk factor. Gastroesophageal reflux of acid and/or bile is linked to these conditions and to reflux esophagitis. Inflammatory disorders can lead to carcinogenesis through activation of "prosurvival genes," including cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS). Increased expression of these enzymes has been found in esophageal adenocarcinoma, Barrett's esophagus, and reflux esophagitis. Polymorphic variants in COX-2 and iNOS genes may be modifiers of risk of these conditions. In a population-based case-control study, we examined associations of the COX-2 8473 T>C and iNOS Ser 608 Leu (C>T) polymorphisms with risk of esophageal adenocarcinoma, Barrett's esophagus, and reflux esophagitis. Genomic DNA was extracted from blood samples collected from cases of esophageal adenocarcinoma (n = 210), Barrett's esophagus (n = 212), and reflux esophagitis (n = 230) and normal population controls frequency matched for age and sex (n = 248). Polymorphisms were genotyped using TaqMan allelic discrimination assays. Odds ratios and 95% confidence intervals were obtained from logistic regression models adjusted for potential confounding factors. The presence of at least one COX-2 8473 C allele was associated with a significantly increased risk of esophageal adenocarcinoma (adjusted odds ratio, 1.58; 95% confidence interval, 1.04-2.40). There was no significant association between this polymorphism and risk of Barrett's esophagus or reflux esophagitis or between the iNOS Ser 608 Leu polymorphism and risk of these esophageal conditions. Our study suggests that the COX-2 8473 C allele is a potential genetic marker for susceptibility to esophageal adenocarcinoma.