Impact of truncating diffusion MRI scans on diffusional kurtosis imaging

Objective Difusional kurtosis imaging (DKI) extends difusion tensor imaging (DTI), characterizing non-Gaussian difusion efects but requires longer acquisition times. To ensure the robustness of DKI parameters, data acquisition ordering should be optimized allowing for scan interruptions or shortening. Three methodologies were used to examine how reduced difusion MRI scans impact DKI histogram-metrics: 1) the electrostatic repulsion model (OptEEM); 2) spherical codes (OptSC); 3) random (RandomTRUNC). Materials and methods Pre-acquired difusion multi-shell data from 14 female healthy volunteers (29±5 years) were used to generate reordered data. For each strategy, subsets containing diferent amounts of the full dataset were generated. The subsampling efects were assessed on histogram-based DKI metrics from tract-based spatial statistics (TBSS) skeletonized maps. To evaluate each subsampling method on simulated data at diferent SNRs and the infuence of subsampling on in vivo data, we used a 3-way and 2-way repeated measures ANOVA, respectively. Results Simulations showed that subsampling had diferent efects depending on DKI parameter, with fractional anisotropy the most stable (up to 5% error) and radial kurtosis the least stable (up to 26% error). RandomTRUNC performed the worst while the others showed comparable results. Furthermore, the impact of subsampling varied across distinct histogram characteristics, the peak value the least afected (OptEEM: up to 5% error; OptSC: up to 7% error) and peak height (OptEEM: up to 8% error; OptSC: up to 11% error) the most afected. Conclusion The impact of truncation depends on specifc histogram-based DKI metrics. The use of a strategy for optimizing the acquisition order is advisable to improve DKI robustness to exam interruptions.info:eu-repo/semantics/publishedVersio

Identification and Characterization of Microsporidia from Fecal Samples of HIV-Positive Patients from Lagos, Nigeria

BACKGROUND: Microsporidia are obligate intracellular parasites that infect a broad range of vertebrates and invertebrates. They have been increasingly recognized as human pathogens in AIDS patients, mainly associated with a life-threatening chronic diarrhea and systemic disease. However, to date the global epidemiology of human microsporidiosis is poorly understood, and recent data suggest that the incidence of these pathogens is much higher than previously reported and may represent a neglected etiological agent of more common diseases indeed in immunocompetent individuals. To contribute to the knowledge of microsporidia molecular epidemiology in HIV-positive patients in Nigeria, the authors tested stool samples proceeding from patients with and without diarrhea. METHODOLOGY/PRINCIPAL FINDINGS: Stool samples from 193 HIV-positive patients with and without diarrhea (67 and 126 respectively) from Lagos (Nigeria) were investigated for the presence of microsporidia and Cryptosporidium using Weber's Chromotrope-based stain, Kinyoun stain, IFAT and PCR. The Weber stain showed 45 fecal samples (23.3%) with characteristic microsporidia spores, and a significant association of microsporidia with diarrhea was observed (O.R. = 18.2; CI: 95%). A similar result was obtained using Kinyoun stain, showing 44 (31,8%) positive samples with structures morphologically compatible with Cryptosporidium sp, 14 (31.8%) of them with infection mixed with microsporidia. The characterization of microsporidia species by IFAT and PCR allowed identification of Enterocytozoon bieneusi, Encephalitozoon intestinalis and E. cuniculi in 5, 2 and 1 samples respectively. The partial sequencing of the ITS region of the rRNA genes showed that the three isolates of E.bieneusi studied are included in Group I, one of which bears the genotype B. CONCLUSIONS/SIGNIFICANCE: To our knowledge, this is the first report of microsporidia characterization in fecal samples from HIV-positive patients from Lagos, Nigeria. These results focus attention on the need to include microsporidial diagnosis in the management of HIV/AIDS infection in Nigeria, at the very least when other more common pathogens have not been detected

Development of technologies to support the diagnosis of infectious diseases and cancer to support the primary health care

54/2017). Publisher Copyright: © 2022, The Author(s).Purpose: Primary Health Care (PHC) is the coordinator of health care in Brazil and needs to be strengthened in the diagnostic field to increase health care quality. Aiming to improve the diagnostic tools currently available in PHC, this work describes the process of development and validation of two point-of-care biomedical devices for screening patients with syphilis or different kinds of cancer. Methods: The development of these devices followed nine stages of action based on the requirements established by the Ministry of Health. During development, both systems followed the stages of circuit planning, software simulation to verify the components used, cost assessment for the acquisition of features, simulation in contact matrix, development of the embedded system, and planning of the printed circuit board and storage box. Results: Both devices underwent preliminary functionality tests to assess their quality. The performance tests applied on the device to diagnose syphilis performed 8,733,194 requests, with a flow of 2426 requests/second, reaching the desired parameters of robustness, integrity, durability, and stability. In addition, functioning tests on the cancer-screening device indicated the ability to detect standard fluorescence in a minimal (150 uL) sample volume. Conclusions: Together, the methodology used for developing the devices resulted in promising equipment to improve the diagnosis and meet the requirements for executing technologies for testing and triaging patients in PHC.publishersversionpublishe

Quasi-free neutron and proton knockout reactions from light nuclei in a wide neutron-to-proton asymmetry range

The quasi-free scattering reactions 11C(p,2p) and 10,11,12C(p,pn) have been studied in inverse kinematics at beam energies of 300–400 MeV/u at the R3B-LAND setup. The outgoing proton-proton and proton-neutron pairs were detected in coincidence with the reaction fragments in kinematically complete measurements. The efficiency to detect these pairs has been obtained from GEANT4 simulations which were tested using the 12C(p,2p) and 12C(p,pn) reactions. Experimental cross sections and momentum distributions have been obtained and compared to DWIA calculations based on eikonal theory. The new results reported here are combined with previously published cross sections for quasi-free scattering from oxygen and nitrogen isotopes and together they enable a systematic study of the reduction of single-particle strength compared to predictions of the shell model over a wide neutron-to-proton asymmetry range. The combined reduction factors show a weak or no dependence on isospin asymmetry, in contrast to the strong dependency reported in nucleon-removal reactions induced by nuclear targets at lower energies. However, the reduction factors for (p,2p) are found to be 'significantly smaller than for (p,pn) reactions for all investigated nuclei.German Federal Ministry of Education and Research | Ref. BMBF 05P2015RDFN1German Federal Ministry of Education and Research | Ref. 05P15WOFNAEuropean Commission | Ref. FP7, ENSAR, n. 262010Comisión Interministerial de Ciencia y Tecnología (CICYT) | Ref. FPA2012-32443Comisión Interministerial de Ciencia y Tecnología (CICYT) | Ref. FPA2015-64969-07387Comisión Interministerial de Ciencia y Tecnología (CICYT) | Ref. FPA2015-69640-C2-1-PSwedish Research Council | Ref. 621-2011-5324National Science Foundation, EE. UU. | Ref. n. 1415656Department of Energy, EE. UU. | Ref. n. DE-FG02-08ER41533Fundação para a Ciência e a Tecnologia | Ref. PTDC/FIS/ 103902/200

The Impact of Symbolic and Substantive Actions on Environmental Legitimacy

Drawing on institutional theory and insights from stakeholder theory and impression management, we empirically analyze the impact of both environmental symbolic polices (participation in voluntary environmental programs, green trademarks, environmental-dedicated board committees, environmental pay policies and community communication) and substantive actions (environmental patents and pollution prevention practices) on environmental legitimacy. We show that (1) symbolic actions have a weaker positive effect on legitimacy than substantive actions, (2) that the impact of symbolic actions is greater when they are combined with substantive actions, (3) that this impact is only short-term while substantive actions have both short- and long-term effects

Strong neutron pairing in core+4n nuclei

The emission of neutron pairs from the neutron-rich N=12 isotones C18 and O20 has been studied by high-energy nucleon knockout from N19 and O21 secondary beams, populating unbound states of the two isotones up to 15 MeV above their two-neutron emission thresholds. The analysis of triple fragment-n-n correlations shows that the decay N19(-1p)C18∗→C16+n+n is clearly dominated by direct pair emission. The two-neutron correlation strength, the largest ever observed, suggests the predominance of a C14 core surrounded by four valence neutrons arranged in strongly correlated pairs. On the other hand, a significant competition of a sequential branch is found in the decay O21(-1n)O20∗→O18+n+n, attributed to its formation through the knockout of a deeply bound neutron that breaks the O16 core and reduces the number of pairs

Quasifree (p, 2p) Reactions on Oxygen Isotopes: Observation of Isospin Independence of the Reduced Single-Particle Strength

Quasifree one-proton knockout reactions have been employed in inverse kinematics for a systematic study of the structure of stable and exotic oxygen isotopes at the R3B/LAND setup with incident beam energies in the range of 300-450 MeV/u. The oxygen isotopic chain offers a large variation of separation energies that allows for a quantitative understanding of single-particle strength with changing isospin asymmetry. Quasifree knockout reactions provide a complementary approach to intermediate-energy one-nucleon removal reactions. Inclusive cross sections for quasifree knockout reactions of the type OA(p,2p)NA-1 have been determined and compared to calculations based on the eikonal reaction theory. The reduction factors for the single-particle strength with respect to the independent-particle model were obtained and compared to state-of-the-art ab initio predictions. The results do not show any significant dependence on proton-neutron asymmetry

Effective proton-neutron interaction near the drip line from unbound states in 25,26 F

Background: Odd-odd nuclei, around doubly closed shells, have been extensively used to study proton-neutron interactions. However, the evolution of these interactions as a function of the binding energy, ultimately when nuclei become unbound, is poorly known. The F26 nucleus, composed of a deeply bound π0d5/2 proton and an unbound ν0d3/2 neutron on top of an O24 core, is particularly adapted for this purpose. The coupling of this proton and neutron results in a Jπ=11+-41+ multiplet, whose energies must be determined to study the influence of the proximity of the continuum on the corresponding proton-neutron interaction. The Jπ=11+,21+,41+ bound states have been determined, and only a clear identification of the Jπ=31+ is missing. Purpose: We wish to complete the study of the Jπ=11+-41+ multiplet in F26, by studying the energy and width of the Jπ=31+ unbound state. The method was first validated by the study of unbound states in F25, for which resonances were already observed in a previous experiment. Method: Radioactive beams of Ne26 and Ne27, produced at about 440AMeV by the fragment separator at the GSI facility were used to populate unbound states in F25 and F26 via one-proton knockout reactions on a CH2 target, located at the object focal point of the R3B/LAND setup. The detection of emitted γ rays and neutrons, added to the reconstruction of the momentum vector of the A-1 nuclei, allowed the determination of the energy of three unbound states in F25 and two in F26. Results: Based on its width and decay properties, the first unbound state in F25, at the relative energy of 49(9) keV, is proposed to be a Jπ=1/2- arising from a p1/2 proton-hole state. In F26, the first resonance at 323(33) keV is proposed to be the Jπ=31+ member of the Jπ=11+-41+ multiplet. Energies of observed states in F25,26 have been compared to calculations using the independent-particle shell model, a phenomenological shell model, and the ab initio valence-space in-medium similarity renormalization group method. Conclusions: The deduced effective proton-neutron interaction is weakened by about 30-40% in comparison to the models, pointing to the need for implementing the role of the continuum in theoretical descriptions or to a wrong determination of the atomic mass of F26

Systematic investigation of projectile fragmentation using beams of unstable B and C isotopes

Background: Models describing nuclear fragmentation and fragmentation fission deliver important input for planning nuclear physics experiments and future radioactive ion beam facilities. These models are usually benchmarked against data from stable beam experiments. In the future, two-step fragmentation reactions with exotic nuclei as stepping stones are a promising tool for reaching the most neutron-rich nuclei, creating a need for models to describe also these reactions. Purpose: We want to extend the presently available data on fragmentation reactions towards the light exotic region on the nuclear chart. Furthermore, we want to improve the understanding of projectile fragmentation especially for unstable isotopes. Method: We have measured projectile fragments from C10,12-18 and B10-15 isotopes colliding with a carbon target. These measurements were all performed within one experiment, which gives rise to a very consistent data set. We compare our data to model calculations. Results: One-proton removal cross sections with different final neutron numbers (1pxn) for relativistic C10,12-18 and B10-15 isotopes impinging on a carbon target. Comparing model calculations to the data, we find that the epax code is not able to describe the data satisfactorily. Using abrabla07 on the other hand, we find that the average excitation energy per abraded nucleon needs to be decreased from 27 MeV to 8.1 MeV. With that decrease abrabla07 describes the data surprisingly well. Conclusions: Extending the available data towards light unstable nuclei with a consistent set of new data has allowed a systematic investigation of the role of the excitation energy induced in projectile fragmentation. Most striking is the apparent mass dependence of the average excitation energy per abraded nucleon. Nevertheless, this parameter, which has been related to final-state interactions, requires further study

Quasi-free (p,pN) scattering of light neutron-rich nuclei around N = 14

Background: For many years, quasifree scattering reactions in direct kinematics have been extensively used to study the structure of stable nuclei, demonstrating the potential of this approach. The RB3 collaboration has performed a pilot experiment to study quasifree scattering reactions in inverse kinematics for a stable C12 beam. The results from that experiment constitute the first quasifree scattering results in inverse and complete kinematics. This technique has lately been extended to exotic beams to investigate the evolution of shell structure, which has attracted much interest due to changes in shell structure if the number of protons or neutrons is varied. Purpose: In this work we investigate for the first time the quasifree scattering reactions (p,pn) and (p,2p) simultaneously for the same projectile in inverse and complete kinematics for radioactive beams with the aim to study the evolution of single-particle properties from N=14 to N=15. Method: The structure of the projectiles O23, O22, and N21 has been studied simultaneously via (p,pn) and (p,2p) quasifree knockout reactions in complete inverse kinematics, allowing the investigation of proton and neutron structure at the same time. The experimental data were collected at the R3B-LAND setup at GSI at beam energies of around 400 MeV/u. Two key observables have been studied to shed light on the structure of those nuclei: the inclusive cross sections and the corresponding momentum distributions. Conclusions: The knockout reactions (p,pn) and (p,2p) with radioactive beams in inverse kinematics have provided important and complementary information for the study of shell evolution and structure. For the (p,pn) channels, indications of a change in the structure of these nuclei moving from N=14 to N=15 have been observed, i.e., from the 0d5/2 shell to the 1s1/2. This supports previous observations of a subshell closure at N=14 for neutron-rich oxygen isotopes and its weakening for the nitrogen isotopes