1,721,102 research outputs found
A planar algebraic description of conditional expectations
Full text linkLet be a unital inclusion of arbitrary von
Neumann algebras. We give a 2-{}-categorical/planar algebraic description
of normal faithful conditional expectations
with finite index and their
duals by means of the
solutions of the conjugate equations for the inclusion morphism
and its conjugate morphism
. In particular, the theory of
index for conditional expectations admits a 2-{}-categorical formulation
in full generality. Moreover, we show that a pair
as above can be described by a Q-system,
and vice versa. These results are due to Longo in the subfactor/simple tensor
unit case [Lon90, Thm.\ 5.2], [Lon94, Thm.\ 5.1].Comment: 20 page
Realization of rigid C*-tensor categories via tomita bimodules
No full textStarting from a (small) rigid C*-tensor category l with simple unit, we construct von Neumann algebras. These algebras are factors of type II or III lambda, lambda is an element of (0, 1]. The choice of type is tuned by the choice of Tomita structure (defined in the paper) on certain bimodules we use in the construction. If the spectrum is infinite we realize the whole tensor category as endomorphisms of these algebras. Furthermore, if the Tomita structure is trivial, the algebras that we get are an amplification of the free group factors with infinitely (possibly uncountably) many generators
Minimal Index and Dimension for 2-C*-Categories with Finite-Dimensional Centers
No full textIn the first part of this paper, we give a new look at inclusions of von Neumann algebras with finite-dimensional centers and finite Jones' index. The minimal conditional expectation is characterized by means of a canonical state on the relative commutant, that we call the spherical state; the minimal index is neither additive nor multiplicative (it is submultiplicative), contrary to the subfactor case. So we introduce a matrix dimension with the good functorial properties: it is always additive and multiplicative. The minimal index turns out to be the square of the norm of the matrix dimension, as was known in the multi-matrix inclusion case. In the second part, we show how our results are valid in a purely 2--categorical context, in particular they can be formulated in the framework of Connes' bimodules over von Neumann algebras
Stress integrated tests and cytological analyses reveal Brassica villosa subsp. drepanensis seed quality decrease upon long-term storage
No full textUnder stress integrated germination test (SIGT), seeds undergo osmo-saline stresses, which enable to detect differences in vigour of long-term stored seeds with high germination percentage (G%). The quality of Brassica villosa subsp. drepanensis seeds stored in a genebank (at -20°C for 16 years) was compared with seeds at harvest by standard germination tests (GT), SIGT and cytogenetic analysis. No differences were detected in G% and mean germination time under GT. Conversely, SIGT performed with NaCl -0.9MPa osmotic potential did not influence G% at harvest but reduced that of stored seeds, SIGT at -1.4MPa reduced G% of both. Cytogenetic analysis showed reduction of mitotic index, appearance of chromosomal aberrations and smaller nucleoli in stored seeds compared with harvest seeds germinated in water. SIGT at -0.9MPa had no effect on mitotic index, but increased chromosome aberrations and nucleoli number. SIGT at -1.4MPa inhibited G% of harvest and stored seeds, reduced mitoses in harvest and completely prevented it in stored seeds. The results indicate that GT does not faithfully reflect the quality of stored seeds, with misinterpretation of their vigour, whereas SIGT and cytogenetical parameters are sensitive, reliable and inexpensive methods for early prediction of genetic erosion in germplasm banks
Nanoparticles effects on growth and differentiation in cell culture of Daucus carota
No full textNanoparticles (NPs) effects on developmental processes like cell
growth, de-differentiation, and embryogenesis were analyzed using the in vitro model
system of Daucus carota L. somatic embryogenesis. Fe3O4 NPs, 6 nm diameter, were
dispensed at doses ranging from 2.01 to 33.5 mg/l to carrot in vitro cultures at different
times, along the stages of cell growth and embryogenic differentiation. Moreover, the
mitotic index of cell cultures under treatments has been cytologically determined. The
results demonstrated that Fe3O4 NPs exposure from 2.01 to 6.70 mg/l slightly affected
growth, mitotic index, and de-differentiation. At the dose of 20.10 mg/l cell growth
and relative mitotic index dropped dramatically, and stopped completely at 33.5 mg/l.
Moreover, these higher doses, entirely blocked embryo formation when treatments were
done along somatic embryogenesis induction. Therefore, this model system seems well
suited to check NPs impact on developmental processes
Genotossicità indotta da bromuro di rame in Vicia sativa L.
No full textIn questo lavoro è stato valutato l’effetto di dosi crescenti di bromuro di rame su semi di Vicia sativa L. impiegando parametri quali percentuale di germinazione, analisi dello sviluppo della plantula e test di genotossicità. I primi due parametri sono risultati essere meno sensibili in quanto differenze morfologiche e fisiologiche non sono state osservate fino alla massima concentrazione di CuBr2 saggiata (5x10-3 M). I test di genotossicità hanno invece rivelato la comparsa di micronuclei e di aberrazioni cromosomiche anche alle dosi più basse di bromuro di rame, dimostrando una maggiore sensibilità di questo approccio e incoraggiandone l’uso in studi di monitoraggio ambientale
Characterization of additives in plastics: from MS to MS10 multistep mass analysis and theoretical calculations of tris(2,4-di-tert-butylphenyl)phosphate
No full textIn the analysis by electrospray (+) of an extract of hemp sprouts put in a polypropylene vial, we found a large contamination of a plastic additive. It was characterized by multiple-stage MSn experiments (MS ÷ MS10) and identified as tris(2,4-di-tert-butylphenyl)phosphate, also known with the synonyms F32IRS6B46, oxidized Naugard 524, and others. The MS2 ÷ MS7 spectra are characterized by consecutive eliminations of six isobutene molecules from the tert-butyl moieties, some of them also occurring in the ion source. The first three are calculated to occur preferentially from the ortho positions, whereas eliminations from the para positions are estimated to be less favored at about 5–6 kcal/mol in each step. Once the first three isobutene molecules are eliminated, the remaining three are lost from the tert-butyl moieties in para positions (MS5 ÷ MS7), yielding protonated triphenylphosphate, whose structure has been confirmed by the MS2 spectrum of triphenylphosphate standard: the latter spectrum is almost superimposable with the MS8 spectrum of the analyte under investigation. MS8 and MS9 spectra show main losses of water and C6H4 molecules. The MS10 spectrum of precursor ions at m/z 215 shows the gas-phase addition of water and methanol and ions at m/z 168, attributable to the loss of a phosphorus oxide radical. Density functional theory (DFT) calculations (Becke 3LYP [B3LYP] 6-311+G(2d,2p)) have been used to evaluate structure and stability of different ionic and neutral species involved in the decomposition pathways and to calculate thermochemical data of the decomposition reactions. This multistep mass analysis combined with theoretical calculations resulted to be particularly useful and effective, yielding chemical, thermochemical, and mechanistic data of significant utility in the structural characterization and identification of the unknown analyte as well as to define its gas-phase reactivity under a multistep low-energy collision-induced dissociation regime
Cytogenetical test to predict the vigour potential in brassica seeds under long-term storage.
No full textPreservation of intraspecific diversity in seed banks is a common strategy to frontier the loss of biodi-
versity, however long-term storage inevitably results in the loss of a certain percentage of seeds, there-
fore causing the genetic erosion of a seed collection. For this reason seed quality monitoring is of out-
standing importance to ensure that the regenerated genetic material is representative of the endemic nat-
ural diversity once reintroduced in the environment, as well as to preserve the genetic biodiversity of
species economically relevant for modern agriculture. Ageing amplification tests, in which seeds under-
go osmotic stresses, enable to detect little differences in the vigour of seeds with high germination per-
centage (%G) thereby allowing to predict precociously damages induced by long-term storage.
In the present research the quality of
Brassica villosa
subsp.
drepanensis
seeds stored in a genebank (at -
20°C for sixteen years) was compared to seeds at harvest (control) by combining %G and mean germina-
tion time (MGT) measurements, ageing amplification tests and cytogenetic changes in primary roots.
Comparison of %G and MGT between control and stored seeds showed no significant differences.
Conversely ageing amplification tests where a saline shock (NaCl -0.9 MPa) was given for six hours
to control seeds or after storage, evidenced no significant influence on %G of control seeds, but sig-
nificantly reduced the % G of stored seeds. The treatment with 1.4 MPa osmotic potential significant-
ly reduced %G of control and stored seeds (50 and 4% respectively).
Cytogenetic analysis clearly showed significant reductions of the mitotic index, the appearance of c
– metaphases, chromosomes laggings and bridges in stored seeds in respect to control seeds germinat-
ed in water. While the treatment with -0.9 MPa osmotic potential had no significant effects in both
groups, the treatment with -1.4 MPa osmotic potential had inhibitory effects in root apices of control
seeds and completely prevented cell division in stored ones.
The results presented in this study indicate that despite a comparable germinative response of seeds,
long-term storage induces cytogenetical damages and increase susceptibility to salt stress, therefore
lowering the seed quality.
We suggest the use of the ageing amplification test and cytogenetical parameters as more sensi-
tive, reliable and inexpensive methods compared to germination percentage tests, allowing an early
prediction of genetic erosion events in germplasm banks and representing a valuable alternative
tool for seed producer
Galois Correspondence and Fourier Analysis on Local Discrete Subfactors
Full text linkDiscrete subfactors include a particular class of infinite index subfactors and all finite index ones. A discrete subfactor is called local when it is braided and it fulfills a commutativity condition motivated by the study of inclusion of Quantum Field Theories in the algebraic Haag–Kastler setting. In Bischoff et al. (J Funct Anal 281(1):109004, 2021), we proved that every irreducible local discrete subfactor arises as the fixed point subfactor under the action of a canonical compact hypergroup. In this work, we prove a Galois correspondence between intermediate von Neumann algebras and closed subhypergroups, and we study the subfactor theoretical Fourier transform in this context. Along the way, we extend the main results concerning α-induction and σ-restriction for braided subfactors previously known in the finite index case
Infinite index extensions of local nets and defects
Full text linkSubfactor theory provides a tool to analyze and construct extensions of
Quantum Field Theories, once the latter are formulated as local nets of von
Neumann algebras. We generalize some of the results of [LR95] to the case of
extensions with infinite Jones index. This case naturally arises in physics,
the canonical examples are given by global gauge theories with respect to a
compact (non-finite) group of internal symmetries. Building on the works of
Izumi, Longo, Popa [ILP98] and Fidaleo, Isola [FI99], we consider generalized
Q-systems (of intertwiners) for a semidiscrete inclusion of properly infinite
von Neumann algebras, which generalize ordinary Q-systems introduced by Longo
[Lon94] to the infinite index case. We characterize inclusions which admit
generalized Q-systems of intertwiners and define a braided product among the
latter, hence we construct examples of QFTs with defects (phase boundaries) of
infinite index, extending the family of boundaries in the grasp of [BKLR16]
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