Time-of-flight scatter rejection in x-ray radiography.

Objective.Time-of-flight (TOF) scatter rejection allows for identifying and discarding scattered photons without the use of an anti-scatter grid (ASG). Although TOF scatter rejection was initially presented for cone-beam computed tomography, we propose, herein, to extend this approach to x-ray radiography. This work aims to evaluate with simulations if TOF scatter rejection can outperform ASGs for radiography.Approach.GATE was used to simulate the radiography of a head and a torso and a water cylinder with bone inserts in a system with total timing jitters from 0 ps up to 500 ps full-width-at-half-maximum. The transmission factor of TOF scatter rejection for primary and scattered photons was evaluated as if it were a virtual ASG.Main results.With a total timing jitter of 50 ps, TOF scatter rejection can reach a selectivity of 4.93 with a primary photons transmission of 99%. Reducing the timing jitter close to 0 ps increases the selectivity up to 15.85 for a head and torso radiography, outperforming typical ASGs which usually have a selectivity from 2.5 to 10 with a primary photons transmission from 50% to 70%.Significance.This suggests that TOF scatter rejection may be suitable to replace ASGs in applications requiring lower radiation exposure if sufficiently low timing jitter is achieved.

Recruitment of activated neutrophils correlates with disease severity in adult Crohn's disease.

Neutrophils are detected in inflamed colon in Crohn's disease (CD). However, whether the frequency and/or activation of circulating or gut tissue neutrophils correlate with endoscopic severity remains to be investigated. A cohort of 73 CD patients was prospectively enrolled according to endoscopic severity and treatment history. Individuals with active disease were stratified using the Montreal classification. Harvey-Bradshaw Index (HBI) and Simple Endoscopic Score for Crohn's Disease (SES-CD) were performed at the time of ileocolonoscopy. Frequency of neutrophils and their expression of CD66b and CD64 were assessed in paired blood and colonic biopsies using flow cytometry. The percentage of neutrophils increased in inflamed colon and correlated with SES-CD in the entire cohort of patients examined, as well as in the subgroup with inflammatory (B1) active disease. SES-CD further correlated with neutrophil CD66b expression in mucosa but not blood and, conversely, with neutrophil CD64 expression in blood but not mucosa. However, the evaluation of neutrophil activation in mucosa when compared to blood reflected disease activity more clearly. Finally, a neutrophil activation power index (CD66b in mucosa X CD64 in blood) that correlated with SES-CD discriminated between patients with mild and severe disease. In conclusion, the frequency and activation of colonic neutrophils correlated with SES-CD, highlighting that mucosal neutrophils are associated with disease severity in CD.

Controlling selectivity in the Ullmann reaction on Cu(111).

Using a surface science approach, the selectivity in the Ullmann cross-coupling of aryl halides on Cu(111) has been understood and controlled. The binding strength of the reactants and repulsion between them dictates which organometallic intermediates form, and hence the product distribution. Cross coupling can be maximized at low reactant concentrations.

Chiral nanoscale pores created during the surface explosion of tartaric acid on Cu(111).

The autocatalytic decomposition of tartaric acid on Cu(111) exhibits unique kinetics, which are linked to a hexagonal surface structure adopted at high coverage. The chirality imposed on the surface by tartaric acid throughout the explosion process is presented, and the hexagonal structure shows promise as a chiral template for enantiospecific surface chemistry.

Influence of step faceting on the enantiospecific decomposition of aspartic acid on chiral Cu surfaces vicinal to Cu{111}.

On surfaces vicinal to Cu{111}, l-aspartic acid (l-Asp) adsorption causes steps to facet enantiospecifically into {310}R and {320}S steps. l-Asp has its highest heat of adsortion on surfaces that naturally expose the {310}R or {320}S steps but decomposes preferentially on the {310}R steps.

Sperm counts and reproductive tract lesions in male Syrian hamsters exposed in utero to diethylstilbestrol.

Pregnant hamsters were administered diethylstilbestrol (DES) orally on day 14 of gestation. Sperm counts from F1 adult males were lower than controls. Significant and consistent lesions were confined to the epididymides of DES exposed males, in which epididymal granulomas were the most common lesion. Epididymal granulomas of the tail have been associated with a bacterial etiology while granulomas of the head may be related to blind ductules or a lack of ductule connection.

Investigations of the vertebrate hosts of eastern equine encephalitis during an epizootic in Michigan, 1980.

A study was undertaken to investigate an increase in reported cases of clinical encephalitis due to eastern equine encephalitis (EEE) virus in horses and to determine the natural vertebrate hosts of that virus. Horses, birds, and small mammals were sampled at sites in a contiguous area in St. Joseph and Kalamazoo counties, Michigan, from 25 August to 5 September 1980. Serum samples from four horses acutely ill with encephalitis and 16 of 39 pasture mates of ill horses had neutralizing (N) antibody against EEE virus (46.5%); no viruses were isolated from these 43 sera. None of 24 draft horses from a site in St. Joseph County 12 km southeast of the affected sites had EEE antibody. A strain of Cache Valley virus was isolated from the blood of one of the 24 draft horses. No viruses were isolated, and no antibodies to EEE virus were detected in 28 blood samples from small mammals captured at sites where equine cases of encephalitis were occurring. Six strains of EEE virus, five of Highlands J virus, and one of Flanders virus were isolated from the blood of 401 wild birds belonging to 42 species captured at eight sites in both counties. A total of 29.9% of the wild birds had EEE antibody. Five species of domestic birds, mostly chickens and ring-necked pheasants, were sampled in both counties. Six strains of EEE virus were isolated from 152 ring-necked pheasants; these included three isolates from the brains of dead birds. About 13% of 51 pheasants tested from two small flocks in backyard pens in Kalamazoo County and 9% of 103 pheasants tested from a large game farm in St. Joseph County had antibody to EEE virus. The source of the EEE virus and the factors responsible for this epizootic are unknown; however, the epizootic probably represented an explosive expansion of an enzootic level of virus transmission.