Thyroid cancer after exposure to external radiation: a pooled analysis of seven studies

The thyroid gland of children is especially vulnerable to the carcinogenic action of ionizing radiation. To provide insights into various modifying influences on risk, seven major studies with organ doses to individual subjects were evaluated. Five cohort studies (atomic bomb survivors, children treated for tinea capitis, two studies of children irradiated for enlarged tonsils, and infants irradiated for an enlarged thymus gland) and two case-control studies (patients with cervical cancer and childhood cancer) were studied. The combined studies include almost 120,000 people (approximately 58,000 exposed to a wide range of doses and 61,000 nonexposed subjects), nearly 700 thyroid cancers and 3,000,000 person years of follow-up. For persons exposed to radiation before age 15 years, linearity best described the dose response, even down to 0.10 Gy. At the highest doses (> 10 Gy), associated with cancer therapy, there appeared to be a decrease or leveling of risk. For childhood exposures, the pooled excess relative risk per Gy (ERR/Gy) was 7.7 (95% CI = 2.1, 28.7) and the excess absolute risk per 10(4) PY Gy (EAR/10(4) PY Gy) was 4.4 (95% CI = 1.9, 10.1). The attributable risk percent (AR%) at 1 Gy was 88%. However, these summary estimates were affected strongly by age at exposure even within this limited age range. The ERR was greater (P = 0.07) for females than males, but the findings from the individual studies were not consistent. The EAR was higher among women, reflecting their higher rate of naturally occurring thyroid cancer. The distribution of ERR over time followed neither a simple multiplicative nor an additive pattern in relation to background occurrence. Only two cases were seen within 5 years of exposure. The ERR began to decline about 30 years after exposure but was still elevated at 40 years. Risk also decreased significantly with increasing age at exposure, with little risk apparent after age 20 years. Based on limited data, there was a suggestion that spreading dose over time (from a few days to > 1 year) may lower risk, possibly due to the opportunity for cellular repair mechanisms to operate. The thyroid gland in children has one of the highest risk coefficients of any organ and is the only tissue with convincing evidence for risk about 1.10 Gy.     

Indoor emissions of total and fluorescent supermicron particles during HOMEChem

Inhalation of particulate matter is associated with adverse health outcomes. The fluorescent portion of supermicron particulate matter has been used as a proxy for bioaerosols. The sources and emission rates of fluorescent particles in residential environments are not well-understood. Using an ultraviolet aerodynamic particle sizer (UVAPS), emissions of total and fluorescent supermicron particles from common human activities were investigated during the HOMEChem campaign, a test-house investigation of the chemistry of indoor environments. Human occupancy and activities, including cooking and mopping, were found to be considerable sources of indoor supermicron fluorescent particles, which enhanced the indoor particle concentrations by two orders of magnitude above baseline levels. The estimated total (fluorescent) mass emission rates for the activities tested were in the range of 4-30 (1-11) mg per person meal for cooking and 0.1-4.9 (0.05-4.7) mg/h for occupancy and mopping. Model calculations indicate that, once released, the dominant fate of coarse particles (2.5-10 micrometer in diameter) was deposition onto indoor surfaces, allowing for the possibility of subsequent resuspension and consequent exposures over durations much longer than the ventilation time scale. Indoor coarse particle deposition would also contribute to soiling of indoor surfaces.     

How users perceive and respond to security messages: a NeuroIS research agenda and empirical study

Users are vital to the information security of organizations. In spite of technical safeguards, users make many critical security decisions. An example is users’ responses to security messages – discrete communication designed to persuade users to either impair or improve their security status. Research shows that although users are highly susceptible to malicious messages (e.g., phishing attacks), they are highly resistant to protective messages such as security warnings. Research is therefore needed to better understand how users perceive and respond to security messages. In this article, we argue for the potential of NeuroIS – cognitive neuroscience applied to Information Systems – to shed new light on users’ reception of security messages in the areas of (1) habituation, (2) stress, (3) fear, and (4) dual-task interference. We present an illustrative study that shows the value of using NeuroIS to investigate one of our research questions. This example uses eye tracking to gain unique insight into how habituation occurs when people repeatedly view security messages, allowing us to design more effective security messages. Our results indicate that the eye movement-based memory (EMM) effect is a cause of habituation to security messages – a phenomenon in which people unconsciously scrutinize stimuli that they have previously seen less than other stimuli. We show that after only a few exposures to a warning, this neural aspect of habituation sets in rapidly, and continues with further repetitions. We also created a polymorphic warning that continually updates its appearance and found that it is effective in substantially reducing the rate of habituation as measured by the EMM effect. Our research agenda and empirical example demonstrate the promise of using NeuroIS to gain novel insight into users’ responses to security messages that will encourage more secure user behaviors and facilitate more effective security message designs.     

A Voltage Phasor Based Fault-classification Method for Phasor Measurement Unit Only State Estimator Output

Abstract—This article presents a fault-classification method for transmission lines based on voltage phasors using classification and regression trees. The proposed method is intended to aid system operators in understanding the outputs of a phasor measurement unit only state estimator. Faults are classified into four categories when the estimator is positive sequence and into ten categories when the estimator is three phase. The fault data are generated in PowerWorld® (PowerWorld Corporation, Champaign, IL, USA) and DSA Tools® (Powertech Labs Inc., Surrey, British Columbia, Canada). The pre-fault state consists of a variety of operating conditions and loading angles of faulted lines. The fault condition comprises different fault types, fault locations, fault impedances, and fault incidence angles. Fault classification is done using MATLAB® (The MathWorks, Natick, Massachusetts, USA).The approach is successfully tested on the IEEE-118 bus system. The results demonstrate that the technique developed here is effective and robust, irrespective of the pre-fault and fault conditions.     

EFFICIENT METHOD OF MOMENTS ESTIMATORS FOR INTEGER TIME SERIES MODELS

The parameters of integer autoregressive models with Poisson, or negative binomial innovations can be estimated by maximum likelihood where the prediction error decomposition, together with convolution methods, is used to write down the likelihood function. When a moving average component is introduced this is not the case. To address this problem an efficient method of moment estimator is proposed where the estimated standard errors for the parameters are obtained using subsampling methods. The small sample properties of the estimator are investigated using Monte Carlo methods, while the approach is demonstrated using two well‐known examples from the time series literature.     

直流电弧等离子体球化U3Si2粉体

研制了直流电弧等离子体球化U3 Si2 粉体装置。在Ar He气氛下对粒度为 1 0～ 1 5 0 μm范围内不规则形状的U3 Si2 粉体进行了球化。球化率达 90 %。     

An Atomistic Understanding of Allosteric Inhibition of Glutamate Racemase: a Dampening of Native Activation Dynamics

Glutamate racemases (GR) are members of the family of bacterial enzymes known as cofactor-independent racemases and epimerases and catalyze the stereoinversion of glutamate. D-amino acids are universally important for the proper construction of viable bacterial cell walls, and thus have been repeatedly validated as attractive targets for novel antimicrobial drug design. Significant aspects of the mechanism of this challenging stereoinversion remain unknown. The current study employs a combination of MD and QM/MM computational approaches to show that the GR from H. pylori must proceed via a pre-activation step, which is dependent on the enzyme's flexibility. This mechanism is starkly different from previously proposed mechanisms. These findings have immediate pharmaceutical relevance, as the H. pylori GR enzyme is a very attractive allosteric drug target. The results presented in this study offer a distinctly novel understanding of how AstraZeneca's lead series of inhibitors cripple the H. pylori GR's native motions, via prevention of this critical chemical pre-activation step. Our experimental studies, using SPR, fluorescence and NMR WaterLOGSY, show that H. pylori GR is not inhibited by the uncompetitive mechanism originally put forward by Lundqvist et al.. The current study supports a deep connection between native enzyme motions and chemical reactivity, which has strong relevance to the field of allosteric drug discovery.     

The structure of latherin,a surfactant allergen protein from horse sweat and saliva

Latherin is a highly surface-active allergen protein found in the sweat and saliva of horses and other equids. Its surfactant activity is intrinsic to the protein in its native form, and is manifest without associated lipids or glycosylation. Latherin probably functions as a wetting agent in evaporative cooling in horses, but it may also assist in mastication of fibrous food as well as inhibition of microbial biofilms. It is a member of the PLUNC family of proteins abundant in the oral cavity and saliva of mammals, one of which has also been shown to be a surfactant and capable of disrupting microbial biofilms. How these proteins work as surfactants while remaining soluble and cell membrane-compatible is not known. Nor have their structures previously been reported. We have used protein nuclear magnetic resonance spectroscopy to determine the conformation and dynamics of latherin in aqueous solution. The protein is a monomer in solution with a slightly curved cylindrical structure exhibiting a ‘super-roll’ motif comprising a four-stranded anti-parallel β-sheet and two opposing α-helices which twist along the long axis of the cylinder. One end of the molecule has prominent, flexible loops that contain a number of apolar amino acid side chains. This, together with previous biophysical observations, leads us to a plausible mechanism for surfactant activity in which the molecule is first localized to the non-polar interface via these loops, and then unfolds and flattens to expose its hydrophobic interior to the air or non-polar surface. Intrinsically surface-active proteins are relatively rare in nature, and this is the first structure of such a protein from mammals to be reported. Both its conformation and proposed method of action are different from other, non-mammalian surfactant proteins investigated so far.     

HIPed Tailored Hollandite Waste Forms for the Immobilization of Radioactive Cs and Sr

Hot isostatically pressed tailored hollandite waste forms were used to demonstrate the immobilization of Cs and Sr are separable from spent nuclear fuel, as well as Ba and Rb. Four hollandite formulations were investigated, two samples with ∼12 wt% waste loading (on an oxide basis) and two with ∼18 wt% waste loading. Two of the samples were Al-substituted and the other two contained Mg. The hollandite in the Al-substituted samples contained all the waste cations, as designed, but this was not the case in the Mg-substituted samples. The hollandite in the Mg-substituted samples did not contain all the waste cations, with ∼50% of the Sr forming SrTiO₃ as a secondary phase. This resulted in waste forms that were not as durable, with respect to Cs, as their Al counterparts. The formation of SrTiO₃ had little effect on the Sr release rates and was not detrimental to the Mg-substituted hollandite waste form. For the Al-substituted samples, the MCC-1 normalized release rates were <0.06 g·(m²·day)⁻¹ at 0–28 days for all elements, while the Cs release rates remained at 2.0 g·(m²·day)⁻¹ at 0–28 days for the Mg-substituted samples.     

FECOM: a new artificial stool for evaluating defecation

OBJECTIVE: Traditionally, barium paste has been used for performing defecography. Because this substance is not stool-like, barium defecography may not accurately represent defecatory function. Our aim was to prospectively compare the utility of a new artificial stool, "FECOM"--a silicon-filled and barium-coated, deformable device the shape and consistency of which mimicked a normal formed stool with that of barium paste. METHODS: Defecography was performed after placing FECOM or barium paste in a random order in 12 healthy subjects (two men and 10 women). We evaluated the changes in anorectal angle, rectal morphology, rectal sensation, and the subjects' preference for a "stool-like" device. RESULTS: Anorectal angle at rest, during squeeze, cough, and straining were each greater with the FECOM when compared with the barium paste (p < 0.006). Anterior rectocele (nine), mucosal intussusception (four), and incontinence (three) were identified only with barium defecography. Nine (75%) subjects preferred FECOM to barium paste (p < 0.001) and reported that expulsion of this device mimicked more closely their stools at home (p < 0.05). CONCLUSION: The anorectal angle is influenced by the form and consistency of stool material and is lower with barium paste. The detection of rectocele, mucosal intussusception, and barium leakage in normal subjects during barium defecography questions the significance of these findings. FECOM appears to be a realistic alternative to barium paste for performing defecography.