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343 result(s) for "Pinna, F"
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Local analysis of absolute instability in plasma jets
Stability features of two-stream coaxial plasma jet simulations are investigated using numerical solutions to the spatio-temporal one-dimensional linear stability theory problem. The base states obtained from magneto-hydrodynamic simulations consider the flow as a mixture of gases in local thermodynamic equilibrium (LTE) while stability computations are performed assuming both a calorically perfect gas (CPG) model and LTE. Comparisons with solutions considering a simple CPG model show the non-negligible impact of the LTE on the stability attributes of the plasma jet. For all cases studied, a large region of absolute instability is found for the axisymmetric mode, starting at the jet inlet. The streamwise evolution of the absolute growth rate is found to depend both on the baroclinic torque and the displacement of the maximum shear toward low velocity regions of the jet, combining effects described in the literature. The jet is controlled by means of electric power and static pressure at constant mass flow. The former affects mainly the absolute growth rate through changes of the core-to-bypass stream velocity ratio, while the latter influences mostly the absolute frequency. Finally, the full impulse response reveals a competition mechanism between the absolute mixed modes dominating at low group velocities, and convective shear layer modes at higher group velocities, restricted to the first half of the chamber.
Global modes of viscous heated jets with real gas effects
This study investigates the stability features of spatially spreading heated jets in the viscous regime with real gas effects, using both unsteady two-dimensional axisymmetric simulations and linear analyses of the steady state and time-averaged states. At a Reynolds number of $400$, the heated jets are found to undergo a subcritical Hopf bifurcation, marking the start of self-sustained oscillations when decreasing the temperature ratio $S=T_{\\infty }/T_{{c}}$, which highly depends on the thermodynamic and transport property assumptions imposed in the simulations. Once the flow enters a limit cycle past the Hopf bifurcation, the linear analyses over the steady base state are unable to capture the oscillation's frequency. Nevertheless, this study confirms that including real gas effects in the stability equations has a strong effect on the growth rate of the global mode once the centreline temperature of the jet reaches that of the dissociation reaction onset, which is $T=2800$ K for air at $p_s=100$ mbar. The linear global analyses over the time-averaged states lead to a satisfying prediction of the oscillation's frequency for the cases studied, and the baroclinic torque obtained from the resulting global mode matches well with that of the simulations.
Exploring the association among the tryptophan to serotonin and kynurenine pathways, cognition and suicidal behaviour: a secondary analysis in a sample of individuals affected by Bipolar Disorder
IntroductionStroop test iteration performances and metabolism of tryptophan (TRP) via serotonin (5-HT) and kynurenine (KYN) have both been associated with suicidal behaviors. This study aims to probe their possible interactions.ObjectivesWe explored the association of the performances on the Emotion Inhibition Subtask (EIS) of the Brief Assessment of Cognition for Affective Disorder and the plasmatic levels of 5-hydroxytryptophan (5-HTP), 5-HT, KYN, melatonin (MLT) among subjects with Lifetime Suicidal Ideation (LSI) vs non-LSI, and with Lifetime Suicide Attempts (LSA) vs non-LSA.MethodsUsing R studio, we employed: 1) the t-test for parametric data and the Wilcoxon test for non-parametric data; 2) Linear Modeling to probe the associations of EIS performances with MLT, KYN, 5-HTP or 5-HT plasmatic levels.ResultsIn a sample comprising 45 individuals affected by Bipolar Disorder, we found a statistically significant difference for the Color Naming (CN, image 1) and the Neutral words (NW) subtasks among LSA vs non-LSA. In LSI vs non-LSI, only the NW retained significance, but not the CN. A significant association emerged between CN and 5-HTP in LSI but not in non-LSI (image 2). Similarly, in LSA, an association was found between CN and 5-HTP, but not in non-LSA (image 3). No statistically significant difference emerged among groups regarding gender composition, age, pharmacological therapy, Body Mass Index, Hamilton Depression Rating Scale, Young Mania Rating Scale, or Clinical Global Impression scale - Severity.Image:Image 2:Image 3:ConclusionsWe found that the plasmatic levels of the metabolites of TRP via 5-HT were correlated to some EIS performances. These findings may represent a hypothesis-generating platform for further investigations.Disclosure of InterestNone Declared
Adventitious buds on roots of Siphanthera arenaria (DC.) Cogn. (Melastomataceae), an annual plant from the cerrado biome
Plants from Brazilian tropical grasslands of the cerrado biome (also referred to as the Cerrado region) are characterized by the possessing of belowground bud-bearing organs that may be of stem or root origin that enhance the likelihood of surviving a dry season or fire. The root-derived bud bank is referred to when speaking about adventitious sprouting from roots. Root buds or root sprouts allow rapid regrowth after a disturbance or a period of adverse climatic conditions and have the potential to generate clonal populations. Adventitious sprouting from roots is well known to occur in Brazil in perennial species, mainly woody plants. In the present study, we investigate the occurrence of adventitious buds on roots of the annual species Siphanthera arenari a (DC.) Cogn., which is endemic to the Serra do Espinhaço range in Brazil and grows in an area of the cerrado biome. Shoots emerging from the root system of S. arenaria were assessed in a microscopic analysis and classified as reparative-type buds emerging from the cortical parenchyma. The presence of root buds in Siphantera arenaria represents the first record for the Melastomataceae family in the cerrado biome and also the first record of a root bud in an annual species for this biome.
First report of laticifers in lianas of Malpighiaceae and their phylogenetic implications
Premise Laticifers have evolved multiple times in angiosperms and have been interpreted as a key innovation involved in plant defense mechanisms. In Malpighiaceae, laticifers were previously known from a single lineage of trees and shrubs, the Galphimia clade, but with detailed anatomical analyses here, we show that their distribution is broader in the family, also encompassing large clades of lianas. Methods From 15 genera, 70 species of Malpighiaceae were surveyed through careful anatomical ontogenetic analysis of roots, stems, and leaves and detailed histochemical tests to elucidate the nature of laticifers and latex in the family. Results Articulated anastomosing laticifers were encountered in roots, stems, and leaves of two distantly related megadiverse genera of Malpighiaceae lianas: Stigmaphyllon (stigmaphylloid clade) and Tetrapterys s.s. (tetrapteroid clade). From the apex downward, in Stigmaphyllon the laticifers are derived from the procambium and from the cambium during its early activity and are present in the outermost part of the vascular cylinder of stems and leaves and in the pericycle of roots, whereas in Tetrapterys s.s. they are derived from the ground meristem, procambium, and cambium throughout the plant body and are present in the cortex and pith, either the pericycle in roots or the outermost part of the vascular system in stems and leaves, and the primary and secondary phloem. Conclusions Laticifers seem to have evolved at least three times independently in Malpighiaceae, once in a lineage of trees and shrubs and twice in two distantly related megadiverse lianescent lineages. Laticifer evolution in Malpighiaceae is homoplastic and may be related to increases in species diversification.
Class I KNOX Is Related to Determinacy during the Leaf Development of the Fern Mickelia scandens (Dryopteridaceae)
Unlike seed plants, ferns leaves are considered to be structures with delayed determinacy, with a leaf apical meristem similar to the shoot apical meristems. To better understand the meristematic organization during leaf development and determinacy control, we analyzed the cell divisions and expression of Class I KNOX genes in Mickelia scandens, a fern that produces larger leaves with more pinnae in its climbing form than in its terrestrial form. We performed anatomical, in situ hybridization, and qRT-PCR experiments with histone H4 (cell division marker) and Class I KNOX genes. We found that Class I KNOX genes are expressed in shoot apical meristems, leaf apical meristems, and pinnae primordia. During early development, cell divisions occur in the most distal regions of the analyzed structures, including pinnae, and are not restricted to apical cells. Fern leaves and pinnae bear apical meristems that may partially act as indeterminate shoots, supporting the hypothesis of homology between shoots and leaves. Class I KNOX expression is correlated with indeterminacy in the apex and leaf of ferns, suggesting a conserved function for these genes in euphyllophytes with compound leaves.
Expression patterns of Passiflora edulis APETALA1/FRUITFULL homologues shed light onto tendril and corona identities
Background Passiflora (passionflowers) makes an excellent model for studying plant evolutionary development. They are mostly perennial climbers that display axillary tendrils, which are believed to be modifications of the inflorescence. Passionflowers are also recognized by their unique flower features, such as the extra whorls of floral organs composed of corona filaments and membranes enclosing the nectary. Although some work on Passiflora organ ontogeny has been done, the developmental identity of both Passiflora tendrils and the corona is still controversial. Here, we combined ultrastructural analysis and expression patterns of the flower meristem and floral organ identity genes of the MADS-box AP1 / FUL clade to reveal a possible role for these genes in the generation of evolutionary novelties in Passiflora . Results We followed the development of structures arising from the axillary meristem from juvenile to adult phase in P. edulis . We further assessed the expression pattern of P. edulis AP1 / FUL homologues ( PeAP1 and PeFUL ), by RT-qPCR and in situ hybridization in several tissues, correlating it with the developmental stages of P. edulis . PeAP1 is expressed only in the reproductive stage, and it is highly expressed in tendrils and in flower meristems from the onset of their development. PeAP1 is also expressed in sepals, petals and in corona filaments, suggesting a novel role for PeAP1 in floral organ diversification. PeFUL presented a broad expression pattern in both vegetative and reproductive tissues, and it is also expressed in fruits. Conclusions Our results provide new molecular insights into the morphological diversity in the genus Passiflora . Here, we bring new evidence that tendrils are part of the Passiflora inflorescence. This points to the convergence of similar developmental processes involving the recruitment of genes related to flower identity in the origin of tendrils in different plant families. The data obtained also support the hypothesis that the corona filaments are likely sui generis floral organs. Additionally, we provide an indication that PeFUL acts as a coordinator of passionfruit development.
Forkhead box M1B is a determinant of rat susceptibility to hepatocarcinogenesis and sustains ERK activity in human HCC
Background and aim:Previous studies indicate unrestrained cell cycle progression in liver lesions from hepatocarcinogenesis-susceptible Fisher 344 (F344) rats and a block of G1–S transition in corresponding lesions from resistant Brown Norway (BN) rats. Here, the role of the Forkhead box M1B (FOXM1) gene during hepatocarcinogenesis in both rat models and human hepatocellular carcinoma (HCC) was assessed.Methods and results:Levels of FOXM1 and its targets were determined by immunoprecipitation and real-time PCR analyses in rat and human samples. FOXM1 function was investigated by either FOXM1 silencing or overexpression in human HCC cell lines. Activation of FOXM1 and its targets (Aurora Kinose A, Cdc2, cyclin B1, Nek2) occurred earlier and was most pronounced in liver lesions from F344 than BN rats, leading to the highest number of Cdc2–cyclin B1 complexes (implying the highest G2–M transition) in F344 rats. In human HCC, the level of FOXM1 progressively increased from surrounding non-tumorous livers to HCC, reaching the highest levels in tumours with poorer prognosis (as defined by patients’ length of survival). Furthermore, expression levels of FOXM1 directly correlated with the proliferation index, genomic instability rate and microvessel density, and inversely with apoptosis. FOXM1 upregulation was due to extracellular signal-regulated kinase (ERK) and glioblastoma-associated oncogene 1 (GLI1) combined activity, and its overexpression resulted in increased proliferation and angiogenesis and reduced apoptosis in human HCC cell lines. Conversely, FOXM1 suppression led to decreased ERK activity, reduced proliferation and angiogenesis, and massive apoptosis of human HCC cell lines.Conclusions:FOXM1 upregulation is associated with the acquisition of a susceptible phenotype in rats and influences human HCC development and prognosis.
Towards the integration of the NUMEN experiment
The most promising probe to establish the Majorana or Dirac nature of the neutrino is the neutrinoless double beta decay and the effective neutrino mass would be evaluated by the knowledge of the corresponding nuclear matrix elements. Also measurements of the Double Charge Exchange (DCE) interactions of heavy ion beams can get information on them. The NUMEN experiment based on the pre-existing large acceptance MAGNEX spectrometer and integrated with new challenging components aims at measuring DCE cross sections using ion beams of unprecedented intensity (10 13 pps) on specific isotopes at INFN-LNS in Catania. Expected rate on the sensitive area of about 0.15 m 2 reaches up to about 5 Mpps, demanding for adequate detectors in measuring position, direction, energy, mass and charge of the ions produced by interactions. Gamma detectors surround a scattering chamber containing the target.
Using TRIM-SRIM code simulations to determine defect density produced in HOPG irradiated with high energy heavy ions
This work is part of the NUMEN Project (NUclear Matrix Elements for Neutrinoless double beta decay), which, among other goals, aims to measure cross-section of double charge exchange reactions (DCE). In the experiments to be carried out at the Laboratori Nazionali del Sud, in Catania, Italy, a target deposited on a carefully chosen backing (substrate) will be irradiated with a high energy ion beam and, importantly, neither the target nor the substrate will be allowed to overheat as this would affect their structures and its properties, which are special for the experiment. Within this context, highly oriented pyrolytic graphite (HOPG) was chosen as a substrate for the deposition of target elements that will be irradiated by ions such as 12 C, 18 O and 20 Ne, with energies ranging from 15 MeV/u to 60 MeV/u. HOPG is considered a semimetal structured in layers, being composed of a stack of graphene sheets with a small and very subtle disorientation (less than 1°), which makes it to approach to a single crystal. With its specific flat hexagonal molecular structure, consisting only of carbon atoms, HOPG has good thermal conductivity in these sheets, making it an excellent candidate as a heat sink. However, for the HOPG to act with thermal energy dissipation functionality during the experiments proposed by the NUMEN project, it is necessary to verify whether possible changes caused by exposure to the radiation beam have a direct or indirect influence on its mechanical and thermal properties. Regarding the thermal conductivity, vacancies produced during irradiation is one of the factors that considerably decrease such property. As the production of vacancies during irradiation is one of the factors that considerably decrease thermal conductivity, in this work it was used the SRIM/TRIM code simulations to investigate the mechanisms of vacancy production in the target plus HOPG backing system. In the simulations, it was considered different types and doses of incident ion beams as well as different target thickness. From the results it was possible to estimated how long a target-HOPG system can be irradiated before the HOPG high heat conductivity property is lost.