Regulation of juvenility in Antirrhinum majus

Floral initiation is regulated by an elaborate network of signalling pathways, including the photoperiodic pathway. In Arabidopsis, flowering is promoted through this pathway by activation of FLOWERING LOCUS T (FT) by CONSTANS (CO) in long days. During juvenility plants are incapable of flowering in response to environmental conditions that would normally be favourable. This project studies the molecular basis of floral incompetence during juvenility in the model annual species, Antirrhinum majus and the important commercial tree species, Olea europaea, which has an extended juvenile phase. Photoperiod transfer experiments were used to measure the length of juvenility in plants grown in controlled environment cabinets at different Daily Light Integrals. Analysis of Antirrhinum FT (AmFT) expression during development showed that AmFT expression is minimal during juvenility and increases in all leaves following the end of the juvenile phase. The photoperiodic pathway was shown to be active during juvenility, suggesting that an additional mechanism involving the repression of FT could be involved in the regulation of juvenility. Full length Antirrhinum and Olive cDNAs representing homologues of the Arabidopsis FT repressors TEMPRANILLO 1 (AtTEM1) and AtTEM2, which act antagonistically with CO, were isolated. Molecular and phylogenetic analyses revealed high amino acid identities between Antirrhinum (AmTEM) and Olive (OeTEM) TEM-like proteins and AtTEM1 & 2. AmTEM and OeTEM proteins contain AP2 and B3 domains, consistent with AtTEM1 and AtTEM2, and can be classified as Class I members of the RAV sub-family of B3 transcription factors. AmTEM and OeTEM expression levels were shown to be higher during juvenility suggesting a potential role for TEM in controlling juvenility. A reciprocal relationship between expression levels of AmTEM/AtTEM1 and AmFT/AtFT was revealed in both Antirrhinum and Arabidopsis. Analysis of expression across development showed that AmTEM/AtTEM1 levels decline at around the time juvenility ends corresponding to when AmFT/AtFT levels start to increase. Arabidopsis tem1 mutants over-expressing AmTEM, OeTEM or AtTEM1 exhibited delayed flowering compared to the tem1 mutant, which demonstrated their role in regulating flowering time. Over-expression of AmTEM was shown to increase the length of the juvenile phase, delay the induction of AtCO and AtFT expression and reduce the overall levels of AtFT expression. Conversely, the juvenile phases of tem1 single and tem1/2 double mutants were shown to be shorter than in wild-type plants, with the induction of AtCO and AtFT expression occurring earlier. These findings are consistent with a role for TEM in regulating juvenility, which occurs through the down-regulation of FT and CO, and results in the inability to proceed to reproductive growth

High luminosity interaction region design for collisions with detector solenoid

An innovatory interaction region has been recently conceived and realized on the Frascati DA{\Phi}NE lepton collider. The concept of tight focusing and small crossing angle adopted until now to achieve high luminosity in multibunch collisions has evolved towards enhanced beam focusing at the interaction point with large horizontal crossing angle, thanks to a new compensation mechanism for the beam-beam resonances. The novel configuration has been tested with a small detector without solenoidal field yielding a remarkable improvement in terms of peak as well as integrated luminosity. The high luminosity interaction region has now been modified to host a large detector with a strong solenoidal field which significantly perturbs the beam optics introducing new design challenges in terms of interaction region optics design, beam transverse coupling control and beam stay clear requirementsComment: 3 pages, 4 figures, presented to the IPAC10 conferenc

Molecular Verification of the UK National Collection of Cultivated Liriope and Ophiopogon Plants

open access articleA collection of cultivated Liriope and Ophiopogon plants was established in 1996–1998 and subsequently hosted at a horticultural college. Uncertainties about the identification of the accessions, compounded by potential errors in propagation and labelling have led to waning confidence in the identities of the plants in the collection. The potential for using DNA barcoding to determine the species identities of the accessions was investigated. The DNA barcode regions of the plastid ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit gene (rbcL) and nuclear ribosomal internal transcribed spacer (nrITS) were amplified. DNA sequence analysis allowed the sequences of the accessions to be compared to reference sequences in public databases. A simple haplotype map of the characteristic polymorphic positions in the rbcL regions was used to clearly distinguish between the two genera and assign Ophiopogon accessions to individual species or sub-groups of species. The ITS sequence data confirmed these genus and species assignations and provided greater resolution to distinguish between closely related species. The combination of two DNA barcodes allowed most of the accessions to be assigned to individual species. This molecular verification confirmed the identity of about 70% of the accessions, with the remaining 30% demonstrating a range of mistaken identities at the species and genus level

DNA Authentication of St John’s Wort (Hypericum perforatum L.) Commercial Products Targeting the ITS Region

open access articleThere is considerable potential for the use of DNA barcoding methods to authenticate raw medicinal plant materials, but their application to testing commercial products has been controversial. A simple PCR test targeting species-specific sequences within the nuclear ribosomal internal transcribed spacer (ITS) region was adapted to screen commercial products for the presence of Hypericum perforatum L. material. DNA differing widely in amount and extent of fragmentation was detected in a number of product types. Two assays were designed to further analyse this DNA using a curated database of selected Hypericum ITS sequences: A qPCR assay based on a species-specific primer pair spanning the ITS1 and ITS2 regions, using synthetic DNA reference standards for DNA quantitation and a Next Generation Sequencing (NGS) assay separately targeting the ITS1 and ITS2 regions. The ability of the assays to detect H. perforatum DNA sequences in processed medicines was investigated. Out of twenty different matrices tested, both assays detected H. perforatum DNA in five samples with more than 103 ITS copies µL−1 DNA extract, whilst the qPCR assay was also able to detect lower levels of DNA in two further samples. The NGS assay confirmed that H. perforatum was the major species in all five positive samples, though trace contaminants were also detected

Closed‐form solution for the Fatemi‐Socie extended critical plane parameter in case of linear elasticity and proportional loading

Fatigue damage remains a significant issue for both metallic and non-metallic components, being the main cause of in-service failures. Among the different assessment methodologies, critical plane methods have gained significance as they enable identifying the critical location and the early crack propagation orientation. However, the standard plane scanning method used for calculating critical plane factors is computationally intensive, and as a result, it is usually applied only when the component's critical region is known in advance. In the presence of complex geometries, loads, or constraints, a more efficient method would be required. This work presents a closed-form solution to efficiently evaluate a critical plane factor based on the Fatemi-Socie criterion, in the case of isotropic linear-elastic material behavior and proportional loading conditions. The proposed algorithm, based on tensor invariants and coordinate transformation laws, was tested on different case studies under various loading conditions, showing a significant reduction in computation time compared to the standard plane scanning method

Regulation of juvenility in Antirrhinum majus

Floral initiation is regulated by an elaborate network of signalling pathways, including the photoperiodic pathway. In Arabidopsis, flowering is promoted through this pathway by activation of FLOWERING LOCUS T (FT) by CONSTANS (CO) in long days. During juvenility plants are incapable of flowering in response to environmental conditions that would normally be favourable. This project studies the molecular basis of floral incompetence during juvenility in the model annual species, Antirrhinum majus and the important commercial tree species, Olea europaea, which has an extended juvenile phase. Photoperiod transfer experiments were used to measure the length of juvenility in plants grown in controlled environment cabinets at different Daily Light Integrals. Analysis of Antirrhinum FT (AmFT) expression during development showed that AmFT expression is minimal during juvenility and increases in all leaves following the end of the juvenile phase. The photoperiodic pathway was shown to be active during juvenility, suggesting that an additional mechanism involving the repression of FT could be involved in the regulation of juvenility. Full length Antirrhinum and Olive cDNAs representing homologues of the Arabidopsis FT repressors TEMPRANILLO 1 (AtTEM1) and AtTEM2, which act antagonistically with CO, were isolated. Molecular and phylogenetic analyses revealed high amino acid identities between Antirrhinum (AmTEM) and Olive (OeTEM) TEM-like proteins and AtTEM1 & 2. AmTEM and OeTEM proteins contain AP2 and B3 domains, consistent with AtTEM1 and AtTEM2, and can be classified as Class I members of the RAV sub-family of B3 transcription factors. AmTEM and OeTEM expression levels were shown to be higher during juvenility suggesting a potential role for TEM in controlling juvenility. A reciprocal relationship between expression levels of AmTEM/AtTEM1 and AmFT/AtFT was revealed in both Antirrhinum and Arabidopsis. Analysis of expression across development showed that AmTEM/AtTEM1 levels decline at around the time juvenility ends corresponding to when AmFT/AtFT levels start to increase. Arabidopsis tem1 mutants over-expressing AmTEM, OeTEM or AtTEM1 exhibited delayed flowering compared to the tem1 mutant, which demonstrated their role in regulating flowering time. Over-expression of AmTEM was shown to increase the length of the juvenile phase, delay the induction of AtCO and AtFT expression and reduce the overall levels of AtFT expression. Conversely, the juvenile phases of tem1 single and tem1/2 double mutants were shown to be shorter than in wild-type plants, with the induction of AtCO and AtFT expression occurring earlier. These findings are consistent with a role for TEM in regulating juvenility, which occurs through the down-regulation of FT and CO, and results in the inability to proceed to reproductive growth.EThOS - Electronic Theses Online ServiceUniversity of WarwickGBUnited Kingdo

Rapid and accurate fatigue assessment by an efficient critical plane algorithm: application to a FSAE car rear upright

The topic of material fatigue is widely discussed and researched in both scientific and industrial communities. Fatigue damage remains a significant issue for both metallic and non-metallic components, leading to unforeseen failures of in-service parts. Critical plane methods are particularly recommended in case of multiaxial fatigue assessment and have gained relevance as they allow for the identification of the component's critical location and early crack propagation. However, the standard method for calculating critical plane factors is time-consuming, utilizing nested for/end loops and, for that, is mainly applied in a research context, or when critical regions are already known. In many cases, the critical area of a component cannot be identified due to complex geometries and loads or time constraints. This becomes particularly relevant after topological optimization of components and, more generally, in lightweight design. An efficient algorithm for critical plane factors evaluation have been recently proposed by the authors. The algorithm applies to all critical plane factors that require the maximization of a specific parameter based on stress and strain components or a combination of them. The methodology is based on tensor invariants and coordinates transformation law. This paper presents and validate the proposed methodology through an automotive case study: the new algorithm was tested on a rear upright of a FSAE car, having complex geometry, subjected to non-proportional loading conditions. The efficient algorithm showed a significant reduction in computation time compared to the (blind search-for) standard plane scanning method, without any loss in solution accuracy

Frequency analysis of random fatigue: setup for an experimental study

The frequency-domain approach to fatigue life estimation in random loading has been largely investigated due to its computational advantages, and several methods for the frequency translation of the most common time-domain methods have been proposed. Between the most known frequency methods there are the Bendat's Method, valid for narrow-band signals, and the Dirlik's formula, which is considered the best result for wide-band signals. However, the great part of the frequency methods takes the rainflow count as a reference time-domain method and uses the rainflow damage computation as the exact value to emulate. Therefore, very few experimental data for fatigue life of mechanical components subject to random loads are available in the literature. This work presents the setup for a series of experimental tests for specimens subjected to random loads, aiming at achieving experimental data to compare with the results provided by frequency methods. After a brief description of the materials used for the setup, the two-step test concept is described: firstly, the specimen will be subjected to random loads obtained by a certain PSD for an amount of time which should nominally cause a 30% of damage; then, the fatigue test will be ended on a resonance testing machine to compute the actual residual fatigue life of the specimen; this two-step testing also allows to reduce the time requested for the tests. The test bench developed for the experimental investigation is described in the paper, together with the results of some preliminary tests, aimed at verifying the feasibility of the conceived procedure

Numerical-experimental characterization of the dynamic behavior of PCB for the fatigue analysis of PCBa

In today's highly digitized and mechatronics-based world, the need for reliable and cost-effective electronic components has become essential. The reliability of these components is not only based on their electrical and circuit aspects but also on their structural properties. This paper presents a study carried out on two-layer Printed Circuit Boards (PCBs) of rectangular shape, which are representative of many industrial applications. The aim of this study is to compare different numerical models, developed in Ansys Workbench and in a FEM software specifically designed for circuit boards, with experimental tests to determine the most interesting ones for further studies on Printed Circuit Board Assemblies (PCBAs). The comparison includes both static and dynamic behaviors, tested through isostatic bending tests and dynamic analyses with a shaker and a fiber optic laser. The models developed are capable of reproducing statics and dynamics of PCBs with varying degrees of accuracy and numerical complexity. However, increasing the details of the models does not always correspond to an increase in accuracy in reproducing the dynamic behavior. Prior to the experimental dynamic analysis, the influence of constraints’ modeling strategies and damping on the first eigenmode was studied, and the results were used to set up tests and simulations to achieve more consistent results. Future work will extend the dynamic characterization to PCBAs by populating the studied PCBs with components, and continue with the study of predictive models for their structural reliability