This work presents the experience developed by the Radioisotope Metrology Laboratory (LMR), of the Argentine National Atomic Energy Commission (CNEA), as result of the accreditation process of the ...Quality System by ISO 17025 Standard. Considering the LMR as a calibration laboratory, services of secondary activity determinations and calibration of activimeters used in Nuclear Medicine were accredited. A peer review of the
(
α
/
β
)
-
γ
coincidence system was also carried out. This work shows in detail the structure of the quality system, the results of the accrediting audit and gives the number of non-conformities detected and of observations made which have all been resolved.
Retinol dehydrogenase 5 (RDH5)-related fundus albipunctatus can present with phenotypic variability. Our purpose was to investigate new clinical characteristics and multimodal imaging findings in ...patients from different ethnic origins, carrying different mutations.
Multicenter international retrospective case series of 18 patients with genetically confirmed RDH5-related fundus albipunctatus. Patients' files were reviewed for fundus images, visual acuity, macular optical coherence tomography scans, near-infrared images, fundus autofluorescence, electroretinogram, and genetic mutations. Imaging and electroretinogram findings.
All eyes (n = 36, 100%) showed small circular findings seen on near-infrared images, termed as the "target sign," correlating to the yellowish dots seen clinically and to the distinct hyperreflective linear lesions on optical coherence tomography at the level between external limiting membrane and retinal pigment epithelium. Perifoveal atrophy with foveal sparing was seen in 4 eyes of 2 patients (both RDH5-c.160C>T, p.R54X mutation). Fundus autofluorescence revealed small hyperautofluorescent dots (n = 16, 44.4%). Scotopic electroretinograms were significantly reduced in all cases with an electronegative pattern, 66.7% displayed cone dysfunction.
Our results show distinct imaging findings present in all patients with fundus albipunctatus independent of ethnicity or genetic mutation. Our results can facilitate the current algorithm to diagnose RDH5-related fundus albipunctatus and allow for targeted genetic testing.
Development of simulated-gas standards Cerutti, G.L.; Iglicki, F.A.
Applied radiation and isotopes,
2002, 2002 Jan-Feb, 2002-1-00, 20020101, Letnik:
56, Številka:
1
Journal Article
Recenzirano
Multigamma simulated-gas standards were developed for monitoring the surrounding air at nuclear power plants by several commercial firms and laboratories. The main advantages of our simulated-gas ...standard consist of the easy preparation, gravimetrically spiking the matrix with a standardised multigamma radioactive solution, and that it does not require to be tested against actual gas standards. Self-attenuation correction factors for low
γ-ray energies were calculated. Original studies about the stability of the adherence of the dried radioactive residue to the matrix are presented and discussed.
In 2005, the Bhabha Atomic Research Centre (BARC), India, and the Comision Nacional de Energia Atomica (CNEA), Argentina, each submitted one sample of known activity of 134Cs to the International ...Reference System (SIR). This was followed in 2006 by the submission of an ampoule by the Institutul de Fizica si Inginerie Nucleara (IFIN-HH), Romania. The values of the activity submitted were between about 0.7 MBq and 1.3 MBq. The 2005 results replace earlier SIR measurements while the 2006 result of the IFIN-HH replaces a CCRI(II) comparison result of 1978. Consequently, there are now thirteen results in the BIPM.RI(II)-K1.Cs-134 comparison for which the key comparison reference value has been updated.
In 2005, the Bhabha Atomic Research Centre (BARC), India, and the Comision Nacional de Energia Atomica (CNEA), Argentina, each submitted one sample of known activity of ...Cs to the International ...Reference System (SIR). This was followed in 2006 by the submission of an ampoule by the Institutul de Fizica si Inginerie Nucleara (IFIN-HH), Romania. The values of the activity submitted were between about 0.7 MBq and 1.3 MBq. The 2005 results replace earlier SIR measurements while the 2006 result of the IFIN-HH replaces a CCRI(II) comparison result of 1978. Consequently, there are now thirteen results in the BIPM.RI(II)-K1.Cs-134 comparison for which the key comparison reference value has been updated. Also, in 2005, the APMP ran a key comparison for the activity of this radionuclide and the results are now linked to the BIPM.RI(II)-K1.Cs-134 comparison through the previous submissions of the pilot laboratory, NMIJ (Japan), and of the LNE-LNHB (France). This has enabled the VNIIM (Russian Federation) to update its result from the 1978 CCRI(II)-K2. Cs-134 comparison and the INER (Chinese Taipei) to be linked for the first time. In addition, the remaining eight eligible results from the 1978 CCRI(II) comparison are still linked provisionally to the SIR results. (ProQuest: ... denotes formulae/symbols omitted.)
Since 2002, the Council for Scientific and Industrial Research-National Metrology Laboratory (CSIR-NML, South Africa) and the Comision Nacional de Energia Atomica (CNEA, Argentina) have each ...submitted a further sample of known activity of 60Co to the International Reference System (SIR) for activity comparison at the Bureau International des Poids et Mesures. The values of the activity submitted were about 210 kBq and 640 kBq respectively.
A
bstract
This paper presents a way to regularize the
t
-channel singularity (which appears when a massive, stable
t
-channel mediator of a given process is allowed to be on-shell, making the cross ...section infinite) in a general case of particles of any spin
0
1
2
1
interacting within a thermal medium. Those interactions result in a finite lifetime of the mediator and allow to introduce an effective momentum- and temperature-dependent width. As a result, the would-be-singular cross section becomes finite. A complete derivation and an analytical result for the width are provided. For an illustration, the method is used to calculate the thermal widths and cross sections within the Vector-Fermion Dark Matter model.
Background/Aims
The aim of our study is to evaluate the association between meals and perceived gastrointestinal symptoms in real life in a French cohort of irritable bowel syndrome (IBS) patients.
...Methods
This prospective cross-sectional observational study included patients from the French association (association des patients souffrant du syndrome de l’intestin irritable APSSII) of IBS. Data were collected on demographics, IBS subtype, dietary food, and meal-induced gastrointestinal symptoms from patient filled self-questionnaires or questionnaires.
Results
Eighty-four patients with IBS were included; 82.3% female with a mean age of 46.9 ± 15.7 years. Each transit pattern subtype represented one-third of the population. Forty-five percent of patients had severe IBS according to IBS-Severity Scoring System; mean IBS Quality of Life score was 53.9 ± 18.3. Patients believed that food could trigger or exacerbate gastrointestinal symptoms in 73.3% and 93.4%, respectively. Eighty-nine percent had already tried diets, mostly lactose free diet and low fermentable, oligosaccharides, disaccharides, monosaccharides, and polyols diet in 61.3% and 53.6% of cases. Thirty-nine percent of meals induced gastrointestinal symptoms. Meal-induced gastrointestinal symptoms were associated with severity and subtype but not with quality of life.
Conclusions
This study has confirmed the important link between gastrointestinal symptoms and food. Gastrointestinal symptoms induced by meals are frequent and associated with severity and IBS-diarrhea subtype. Our study also underlines patients’ interest in food and diet. More knowledge is needed on food that triggers IBS symptoms but also on diet conditions in order to improve this condition.
(J Neurogastroenterol Motil 2021;27:574-580)
The t-channel singularity of a cross section for a binary 2→2 scattering occurs when the particle exchanged in the t-channel is kinematically allowed to be on its mass shell, that is when the process ...can be viewed as a sequence of two physical subprocesses: a two-body decay 1→2 and an inverse decay 2→1. We derive conditions for the singularity to be present in a binary process. A class of divergent cross sections for Standard Model processes has been determined and illustrated by the weak analog of the Compton scattering Ze−→Ze−. After critically reviewing regularization methods proposed in literature, we discuss singular processes that occur in a medium composed of particles in thermal equilibrium. The medium is shown to regulate the singularities naturally as particles acquire a non-zero width. We demonstrate a possible cosmological application by calculating thermally averaged cross section for an elastic scattering within a simple scalar model. The transition probability, which is divergent in vacuum, becomes finite when the process occurs in a thermal bath due to the imaginary part of the t-channel mediator's self-energy computed within the Keldysh-Schwinger formalism.
