1,333 research outputs found
An Iron-Catalyzed Bond-Making/Bond-Breaking Cascade Merges Cycloisomerization and Cross-Coupling Chemistry
Treatment of readily available enynes with alkyl-Grignard reagents in the presence of catalytic amounts of Fe(acac)3 engenders a remarkably facile and efficient reaction cascade that results in the net formation of two new C−C bonds while a C−Z bond in the substrate backbone is broken. Not only does this new manifold lend itself to the extrusion of heteroelements (Z=O, NR), but it can even be used for the cleavage of activated C−C bonds. The reaction likely proceeds via metallacyclic intermediates, the iron center of which gains ate character before reductive elimination occurs. The overall transformation represents a previously unknown merger of cycloisomerization and cross-coupling chemistry. It provides ready access to highly functionalized 1,3-dienes comprising a stereodefined tetrasubstituted alkene unit, which are difficult to make by conventional means
Assessment of Neuropsychological Trajectories in Longitudinal Population-Based Studies of Children
This paper provides a strategy for the assessment of brain function in longitudinal cohort studies of children. The proposed strategy invokes both domain-specific and omnibus intelligence test approaches. In order to minimise testing burden and practice effects, the cohort is divided into four groups with one-quarter tested at 6-monthly intervals in the 0–2-year age range (at ages 6 months, 1.0, 1.5 and 2.0 years) and at annual intervals from ages 3–20 (one-quarter of the children at age 3, another at age 4, etc). This strategy allows investigation of cognitive development and of the relationship between environmental influences and development at each age. It also allows introduction of new domains of function when age-appropriate. As far as possible, tests are used that will provide a rich source of both longitudinal and cross-sectional data. The testing strategy allows the introduction of novel tests and new domains as well as piloting of tests when the test burden is relatively light. In addition to the recommended tests for each age and domain, alternative tests are described. Assessment methodology and knowledge about child cognitive development will change over the next 20 years, and strategies are suggested for altering the proposed test schedule as appropriate
Interoperability and governance in the European Health Data Space regulation
The proposal for a regulation on the European Health Data Space (EHDS) is a much-awaited project. It aspires to create a harmonised framework – a common European data space – for the administration of health data (primary use) across Member States and the promotion of healthcare research and innovation (by establishing rules for the secondary use of health data). As such, although the EHDS proposal is a legal document, in its essence, it includes provisions that introduce not only legal, but also institutional, and technical-infrastructural changes. Overall, together with the Regulation 2017/745 on medical devices, the Data Governance Act (DGA), the Data Act, the AI Act, and the General Data Protection Regulation (GDPR), the EHDS proposal will complete the regulatory canvas for the use of health data in the European Union. Although we are supportive of the EHDS initiative, there are aspects of the proposal that require further debate, reconsideration, and amendments. Following previous work on potential power asymmetries encapsulated in the Proposal, in this commentary, we focus on the provisions of/for interoperability of the Electronic Health Record (EHR) systems (Ar. 14–32) as well as the provisions on the structure of Health Data Access bodies and their cross-border organisation (section 3). We recommend a series of amendments to orientate the EHDS project better to its constitutive goals: the promotion of public health research and respect for the rights of the individuals
A note on the cylindrical collapse of counter-rotating dust
We find analytical solutions describing the collapse of an infinitely long
cylindrical shell of counter-rotating dust. We show that--for the classes of
solutions discussed herein--from regular initial data a curvature singularity
inevitably develops, and no apparent horizons form, thus in accord with the
spirit of the hoop conjecture.Comment: 8 pages, LaTeX, ijmpd macros (included), 1 eps figure; accepted for
publication in Int. J. Mod. Phys.
Space-mapping techniques applied to the optimization of a safety isolating transformer
Space-mapping optimization techniques allow to allign low-fidelity and high-fidelity models in order to reduce the computational time and increase the accuracy of the solution. The main idea is to build an approximate model from the difference of response between both models. Therefore the optimization process is computed on the surrogate model. In this paper, some recent approaches of space-mapping techniques such as agressive-space-mapping, output-mapping and manifold-mapping algorithms are applied to optimize a safety insulating transformer. The electric, magnetic and thermal phenomena of the device are modeled by an analytical model and a 3D finite element model. It is considered as a benchmark for multi-level optimization to test different algorithms
Combining the Burrows-Wheeler Transform and RCM-LDGM Codes for the Transmission of Sources with Memory at High Spectral Efficiencies
In this paper, we look at the problem of implementing high-throughput Joint SourceChannel (JSC) coding schemes for the transmission of binary sources with memory over AWGN channels. The sources are modeled either by a Markov chain (MC) or a hidden Markov model (HMM). We propose a coding scheme based on the Burrows-Wheeler Transform (BWT) and the parallel concatenation of Rate-Compatible Modulation and Low-Density Generator Matrix (RCM-LDGM) codes. The proposed scheme uses the BWT to convert the original source with memory into a set of independent non-uniform Discrete Memoryless (DMS) binary sources, which are then separately encoded, with optimal rates, using RCM-LDGM codes
In vitro development of murine embryos in presence of Campylobacter fetus
Bovine campylobacteriosis caused by Campylobacter fetus is associated with reproductive losses. The knowledge about the mechanisms of bacterial pathogenesis is limited, then a murine experimental model is proposed. BALB/c females and males were used. Two-cell embryos were cultured in Ham-F10 as control group (CG). Treatment groups were constituted by the addition of Cfv 1 and 3, or Cff 2 and 5. Morulae were placed in Ham-F10 (CG); treatment groups were constituted by the addition of Cfv27, CFF (cell- free filtrate) and Brucella broth (BB). Blastocysts were cultured in MEM (CG); challenge group were constituted by the addition of Cfv 27. Differentiation, hatching, hatched, adhesion and expansion were evaluated. Results were analyzed by Chi2 test. In two-cell embryo, the differentiation rate was not modified when the study strains were added (p > 0.05). The differentiation rate at 24 h for embryos at the morula stage was lower for BB, Cfv, and CFF, compared with CG (p 0.05). However, the differentiation rate for the CFF group was lower than for CG (p < 0.05). At 48 and 72 h, the hatching rate was higher in CFF and Cfv groups than in CG (p < 0.05). Differences were not detected in blastocyst cultures. In conclusion, under these experimental conditions, Cf was not detrimental to the development of murine embryos. Efforts will be intensified to establish in vitro infection models that reproduce their pathogenicity.Fil: Catena, MarÃa. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico - CONICET - Tandil. Centro de Investigacion Veterinaria de Tandil; Argentina;Fil: Teruel, Miriam. Universidad Nacional del Centro de la Provincia de Bs.as.. Facultad de Cs.veterinarias. Departamento de Fisiopatologia. Cat. de Reproduccion; Argentina;Fil: Morán, P.. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico - CONICET - Tandil. Centro de Investigacion Veterinaria de Tandil; Argentina;Fil: Chiapparrone, MarÃa Laura. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico - CONICET - Tandil. Centro de Investigacion Veterinaria de Tandil; Argentina;Fil: Echeverria, Hernan Eduardo. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico - CONICET - Tandil. Centro de Investigacion Veterinaria de Tandil; Argentina;Fil: Soto, Pedro. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico - CONICET - Tandil. Centro de Investigacion Veterinaria de Tandil; Argentina
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