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.
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.
Multi-component dark matter scenarios constitute natural extensions of standard single-component setups and offer attractive new dynamics that could be adopted to solve various puzzles of dark ...matter. In this work we present and illustrate properties of a minimal UV-complete vector-fermion dark matter model where two or three dark sector particles are stable. The model we consider is an extension of the Standard Model (SM) by spontaneously broken extra
U
(
1
)
X
gauge symmetry and a Dirac fermion. All terms in the Lagrangian which are consistent with the assumed symmetry are present, so the model is renormalizable and consistent. To generate mass for the dark-vector
X
μ
the Higgs mechanism with a complex singlet
S
is employed in the dark sector. Dark matter candidates are the massive vector boson
X
μ
and two Majorana fermions
ψ
±
. All the dark sector fields are singlets under the SM gauge group. The set of three coupled Boltzmann equations has been solved numerically and discussed. We have performed scans over the parameter space of the model implementing the total relic abundance and direct detection constraints. The dynamics of the vector-fermion dark matter model is very rich and various interesting phenomena appear, in particular, when the standard annihilations of a given dark matter are suppressed then the semi-annihilations, conversions and decays within the dark sector are crucial for the evolution of relic abundance and its present value. Possibility of enhanced self-interaction has been also discussed.
A
bstract
Recent dark matter (DM) direct searches place very stringent constraints on the possible DM candidates proposed in extensions of the Standard Model. There are however models where these ...constraints are avoided. One of the simplest and most striking examples comes from a straightforward Higgs-portal pseudo-scalar DM model featured with a softly broken U(1) symmetry. In this model the tree-level DM-nucleon scattering cross section vanishes in the limit of zero momentum transfer. It has also been argued that the leading-order DM-nucleon cross section appears at the one-loop level. In this work we have calculated the exact cross section in the zero momentum transfer at the leading order i.e., at the one-loop level of perturbative expansion. We have concluded that, in agreement with expectations, the amplitude for the scattering process is UV finite and approaches zero in the limit of vanishing DM masses. Moreover, we made clear that the finite DM velocity correction at tree level is subdominant with respect to the one-loop contribution. Based on the analytic formulae, our numerical studies show that, for a typical choice of model parameters, the DM nuclear recoiling cross section is well below
O
(10
−50
cm
2
), which indicates that the DM direct detection signal in this model naturally avoids present strong experimental limits on the cross section.
Inflammation is substantially contributing to the development and worsening of diabetic retinopathy in general and diabetic macular edema (DME) in particular, which provides the rationale to treat ...DME with corticosteroids. While anti-vascular endothelial growth factor (VEGF) agents are mostly chosen as a first-line treatment, there is an important role for steroids in the treatment algorithm for DME. A slow-release bioerodible dexamethasone implant and an extended-release nonbioerodible fluocinolone acetonide insert are both approved for the treatment of DME and provide the advantage of sustained drug delivery and reduced treatment burden. Steroids bare the complications of cataract progression and increase of intraocular pressure (IOP). However, with dexamethasone implant, IOP rise is well manageable with topical treatment in almost all cases. Dexamethasone implant has been shown to be effective in the treatment of naive DME as well as in eyes nonresponding to anti-VEGF agents. In these cases, early switching to steroids may be considered and has been shown to be beneficial. Fluocinolone acetonide is reserved for severe cases of chronic DME insufficiently responsive to other available therapies. Future randomized controlled trials are needed to realize the role of steroids in the current treatment algorithm of DME.
The treatment and outcomes of diabetic macular oedema (DMO) have improved with the introduction of intravitreal injections. However, real-world data reveal that the burden of DMO treatment causes ...large gaps in outcomes between randomized clinical trials and daily clinical practice. Long-lasting intravitreal drugs and devices for DMO might reduce this disparity by achieving optimal treatment due to more feasible injection regimens. In this manuscript, we cover pharmacodynamics, preliminary results from clinical trials, and safety behavior about brolucizumab, faricimab, conbercept, KSI-301, and port-delivery system WR42221. These treatments might present the first step to control the global epidemic of diabetic eye disease in real life.
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