Meiosis is a defining feature of eukaryotes but its phylogenetic distribution has not been broadly determined, especially among eukaryotic microorganisms (i.e. protists)-which represent the majority ...of eukaryotic 'supergroups'. We surveyed genomes of animals, fungi, plants and protists for meiotic genes, focusing on the evolutionarily divergent parasitic protist Trichomonas vaginalis. We identified homologs of 29 components of the meiotic recombination machinery, as well as the synaptonemal and meiotic sister chromatid cohesion complexes. T. vaginalis has orthologs of 27 of 29 meiotic genes, including eight of nine genes that encode meiosis-specific proteins in model organisms. Although meiosis has not been observed in T. vaginalis, our findings suggest it is either currently sexual or a recent asexual, consistent with observed, albeit unusual, sexual cycles in their distant parabasalid relatives, the hypermastigotes. T. vaginalis may use meiotic gene homologs to mediate homologous recombination and genetic exchange. Overall, this expanded inventory of meiotic genes forms a useful "meiosis detection toolkit". Our analyses indicate that these meiotic genes arose, or were already present, early in eukaryotic evolution; thus, the eukaryotic cenancestor contained most or all components of this set and was likely capable of performing meiotic recombination using near-universal meiotic machinery.
Diversity and distribution of ascidians Stefaniak, Lauren M.
Genesis (New York, N.Y. : 2000),
November 2023, 2023-Nov, 2023-11-00, 20231101, Volume:
61, Issue:
6
Journal Article
EPOS Werner, K.; Guiot, B.; Karpenko, Iu ...
EPJ Web of Conferences,
2019, Volume:
208
Journal Article, Conference Proceeding
Peer reviewed
Open access
We summarize the main features of the hadronic interaction model EPOS, which is used for cosmic ray air shower simulations but also for p-p, p-A, and A-A collisions to be compared with experimental ...data from LHC and RHIC.
In 2017, the PCAOB began requiring audit firm tenure disclosure within the audit report for SEC registrant clients. Many commenters raised the concern that prominent disclosure of firm tenure would ...lead investors to inappropriately infer a negative relation between audit quality and long tenure. This is particularly troubling given that empirical evidence generally does not support this concern. In our first experiment, we predict and find that disclosing an audit firm's long tenure within the audit report increases investors' perceptions that the audit firm's independence was impaired while conducting the audit. However, we also identify an intervention that mitigates the effects of disclosing long tenure—an accompanying disclosure in the audit report of the firm's adherence to the SEC's mandatory partner rotation requirement. We find that such a disclosure moderates the effect of long tenure disclosure such that in the absence (presence) of a partner rotation disclosure, investors do (do not) perceive increased independence impairment when long firm tenure is disclosed. In a second experiment, we predict and find that long firm tenure disclosure reduces investors' preference to invest in an otherwise quantitatively optimal investment and that this relation is driven, in part, by perceptions of independence impairment. Again, this result is attenuated by partner rotation disclosure. Our results should be useful to regulators in understanding the effects of their disclosure mandate and to audit firms in understanding a practical way in which they might mitigate the implications of such effects.
Résumé
Divulgation de la durée du mandat des cabinets d’audit et perceptions des investisseurs de détail quant à l’indépendance de l’auditeur : l’effet atténuateur de la divulgation de la rotation des associés
Depuis 2017, la Commission de surveillance de la comptabilité des sociétés cotées en bourse exige que la durée du mandat des cabinets d’audit soit divulguée dans le rapport d’audit pour les émetteurs inscrits auprès de la SEC. De nombreux commentateurs se sont montrés préoccupés par le fait que la divulgation de la durée du mandat des cabinets permette aux investisseurs de déduire à tort l’existence d’une relation négative entre la qualité de l’audit et la durée du mandat du cabinet. Cela est d’autant plus inquiétant qu’en général, les données empiriques ne corroborent pas cette préoccupation. Dans une première expérience, les auteurs formulent et confirment l’hypothèse suivante : la divulgation de l’ancienneté d’un cabinet d’audit dans le rapport d’audit facilite la perception qu’ont les investisseurs quant à une perte d’indépendance du cabinet d’audit lors de la réalisation de l’audit. Cependant, les auteurs identifient également une intervention qui atténue les effets de la divulgation de l’ancienneté, à savoir la divulgation dans le rapport d’audit de l’entreprise de son obligation de rotation des associés imposée par la SEC. Ils constatent que cette information atténue l’effet de la divulgation de l’ancienneté, de sorte qu’en l’absence (présence) d’une information sur la rotation des associés, les investisseurs perçoivent (ne perçoivent pas) une plus grande perte d’indépendance lorsque l’ancienneté est divulguée. Dans une deuxième expérience, les auteurs formulent et confirment l’hypothèse suivante : les investisseurs affichent une préférence moins marquée pour un choix d’investissement autrement optimal sur le plan quantitatif, et cette relation est due, en partie, à la perception de la perte d’indépendance. Là encore, cet effet est atténué par la divulgation de la rotation des associés. Les résultats de l’étude devraient aider les régulateurs à comprendre les effets de la divulgation qu’ils exigent et les cabinets d’audit à comprendre comment ils pourraient atténuer les conséquences de ces effets.
The aim of this paper is to understand resonance production (and more generally particle production) for different collision systems, namely proton-proton (pp), proton-nucleus (pA), and ...nucleus-nucleus (AA) scattering at the LHC. We will investigate in particular particle yields and ratios versus multiplicity, using the same multiplicity definition for the three different systems, in order to analyse in a compact way the evolution of particle production with the system size and the origin of a very different system size dependence of the different particles.
The azimuthal anisotropy in particle emission in the transverse plane, known as anisotropic flow, is used to study the properties of strongly interacting hot and dense medium created in heavy-ion ...collisions. Anisotropic flow coefficients are the key observables which reflect the viscous hydrodynamic response to the initial spatial anisotropy, produced in the early stages of the collision. In previous studies performed by the Solenoidal Tracker At RHIC (STAR) collaboration at the Relativistic Heavy Ion Collider (RHIC) the increase of the elliptic flow (
) difference between particles and antiparticles at the lower collision energies has been observed. In these proceedings we present the measurement of the two-particle elliptic and triangular flow correlations for identified particles performed by the STAR experiment. Our measurements are compared with the EPOS model simulations as well.
The widespread success of the invasive colonial ascidian
Didemnum vexillum
has led to descriptions of the species as fast-growing and competitively dominant, with few predators in its introduced ...range. However, recent experiments assessing the competitive strength and predation resistance of
D. vexillum
suggest that this ascidian is not a stronger competitor compared to other non-native colonial ascidians (e.g.,
Botrylloides violaceus
,
Botryllus schlosseri
). To examine this apparent contradiction, juvenile
D. vexillum
colonies of varying size and age from an invasive population were exposed to competitive interactions with other epifaunal invertebrates and predation by mobile benthic invertebrates. Results indicate that both competition and predation had a significant negative effect on
D. vexillum
growth as well as on the composition of and percent cover of
D. vexillum
in 6- to 8-week-old experimental communities. In smaller colonies, predation also had a significant negative effect on
D. vexillum
survival. The discrepancy between field observations describing
D. vexillum
as a superlative competitive dominant and recent manipulative experiments indicating the opposite may be a function of the intrinsic life history characteristics of
D. vexillum
: (a) frequent colony fusion in non-native regions, (b) transport of larvae over relatively long distances via tendril detachment, (c) unique formation of colony mats on pebble substrates, and (d) calcified structures embedded in the tunic. The combined effects of these characteristics could make non-native populations of
D. vexillum
appear to be competitively dominant species with few predators, even though manipulative experiments on individual colonies suggest otherwise.
Using D. vexillum populations in the northeastern USA, several features of growth and sexual reproduction, as well as asexual reproduction via the unusual feature of detachment of larva-laden ...tendrils were examined from 2008 to 2011. Examination of paired samples of encrusting and tendril growth forms collected on 22 July 2010 in Newport, RI, revealed no significant differences in densities of reproductive structures between growth forms. One hundred percent of tendrils reattached within 48 h to PVC panels in the laboratory, while only 1 in 80 tendrils tethered to bare substrates (rock or concrete) at nearby field sites reattached to the substrate. Overall, we found that the tendril growth form is an important factor in the population biology of D. vexillum because it increases surface area for feeding and reproducing zooids in a space-limited environment.
Although the use of highly active antiretroviral therapy in the treatment of HIV infection has led to considerable improvement in morbidity and mortality, unless patients are adherent to their drug ...regimen (i.e., at least 90 to 95% of doses taken), viral replication may ensue and drug-resistant strains of the virus may emerge.
The authors studied the extent to which neuropsychological compromise and medication regimen complexity are predictive of poor adherence in a convenience sample of 137 HIV-infected adults. Medication adherence was tracked through the use of electronic monitoring technology (MEMS caps).
Two-way analysis of variance revealed that neurocognitive compromise as well as complex medication regimens were associated with significantly lower adherence rates. Cognitively compromised participants on more complex regimens had the greatest difficulty with adherence. Deficits in executive function, memory, and attention were associated with poor adherence. Logistic regression analysis demonstrated that neuropsychological compromise was associated with a 2.3 times greater risk of adherence failure. Older age (>50 years) was also found to be associated with significantly better adherence.
HIV-infected adults with significant neurocognitive compromise are at risk for poor medication adherence, particularly if they have been prescribed a complex dosing regimen. As such, simpler dosing schedules for more cognitively impaired patients might improve adherence.
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