238 research outputs found
Film antitranspirant application to enhance spring drought tolerance of oilseed rape (Brassica napus L.)
Oilseed rape (OSR) is an important crop worldwide and drought occurring during
reproduction is the main limitation on yield. Following the recent problems in
breeding new drought tolerant OSR varieties, there is potential for agronomic
exploitation of film antitranspirant (AT) application to avoid yield losses.
The main objectives of this study were i) to evaluate whether AT application during
OSR r
eproductive stages may sustain yield under drought; ii) to elucidate the
physiological mechanisms behind the potential AT-
induced yield mitigation; iii) to
explore the apparent physiological inconsistency between the old and the new
work on AT.
In
four glasshouse
experiments
and two field experiments
drought
conditions were
applied at different phenological stages and OSR plants were sprayed with
different AT chemicals. Three experiments were carried out on OSR seedlings in
growth chambers under different atmospheric CO
2
concentration, drought
conditions and sprayed or not with AT.
The data showed physiological amelioration and yield loss mitigation from
application of 1% v/v (glasshouse) and 1 L ha
-1
(field)
of a commercially
-available
AT (Vapor Gard) jus
t prior to flowering
(GS 6.0) on droughted OSR
. The
AT
application under drought triggered complex physiological mechanisms,
collectively leading to a sustained photosynthetic rate, reductions in ABA
concentration, improved leaf water status and therefore sustaining pod and, to a
greater extent, seed production. In addition, the data show that increasing the
atmospheric CO
2
concentration does not have an ameliorative effect on OSR
seedling’s drought tolerance. On the contrary, the experiments showed that in
recent years the increased atmospheric CO
2
concentration may have counteracted
the source-
limiting effect of AT following increasing substrate available at the site
of carboxylation, therefore leading to higher potential efficiency of AT chemicals
under w
ater
-limited conditions.
To conclude, AT may deserve further investigation as a potential and flexible
management tool to counteract drought damage to OSR yield
In-field film antitranspirants application shows potential yield protection from flowering 1 stage drought periods in winter canola (Brassica napus L.)
Crop-management solutions that simulate plant water-saving strategies might help to mitigate drought damage in crops. Winter canola (Brassica napus L.) is significantly drought-sensitive from flowering to mid-pod development, and drought periods lead to significant yield losses. In this study, the drought-protection efficacy of different chemicals with antitranspirant activity applied just before key drought-sensitive phenological stages was tested on field-grown canola in two years. Drought was artificially imposed with rain shelters. The results suggest that in-field application of 1 L ha–1 of antitranspirant (Vapor Gard (VG), a.i. di-1-p-menthene) at GS6.0 (BBCH growth scale, initiation of flowering) mitigated drought-induced yield loss leading to a 22% seed-yield benefit on average over 2 years of experiments compared with the unsprayed unirrigated plots. No significant yield responses were found from application at GS7.0, with increasing VG concentrations (i.e. 2 and 4 L ha–1), or with an antitranspirant with short-lasting effectiveness. The data suggest that in field conditions where drought occurs during the flowering stage, application of 1 L ha–1 of VG just before the drought event can reduce yield loss. This result should encourage further work on water-saving management strategies during key drought-sensitive phenological stages as drought mitigation tools in canola and under different environments
Leaf monoterpene emission limits photosynthetic downregulation under heat stress in field-grown grapevine
Rising temperature is among the most remarkably stressful phenomena induced by global climate changes with negative impacts on crop productivity and quality. It has been previously shown that volatiles belonging to the isoprenoid family can confer protection against abiotic stresses. In this work, two Vitis vinifera cv. ‘Chardonnay’ clones (SMA130 and INRA809) differing due to a mutation (S272P) of the DXS gene encoding for 1-deoxy-D-xylulose-5-phosphate (the first dedicated enzyme of the 2C-methyl-D-erythritol-4-phosphate (MEP) pathway) and involved in the regulation of isoprenoids biosynthesis were investigated in field trials and laboratory experiments. Leaf monoterpene emission, chlorophyll fluorescence and gas-exchange measurements were assessed over three seasons at different phenological stages and either carried out in in vivo or controlled conditions under contrasting temperatures. A significant (p < 0.001) increase in leaf monoterpene emission was observed in INRA809 when plants were experiencing high temperatures and over two experiments, while no differences were recorded for SMA130. Significant variation was observed for the rate of leaf CO2 assimilation under heat stress, with INRA809 maintaining higher photosynthetic rates and stomatal conductance values than SMA130 (p = 0.003) when leaf temperature increased above 30 °C. At the same time, the maximum photochemical quantum yield of PSII (Fv/Fm) was affected by heat stress in the non-emitting clone (SMA130), while the INRA809 showed a significant resilience of PSII under elevated temperature conditions. Consistent data were recorded between field seasons and temperature treatments in controlled environment conditions, suggesting a strong influence of monoterpene emission on heat tolerance under high temperatures. This work provides further insights on the photoprotective role of isoprenoids in heat-stressed Vitis vinifera, and additional studies should focus on unraveling the mechanisms underlying heat tolerance on the monoterpene-emitter grapevine clone
Recurrent Non-Hodgkin’s lymphoma in the uterine cervix: a case report and a review of the literature
Background. Lymphomas are a heterogeneous group of malignant lymphoproliferative diseases. As primary localization, the most common histological subtype of female genital lymphomas is a Non-Hodgkin Lymphoma (NHL), the diffuse large B-cell type. However cervical relapse of NHL is a very rare condition (0.3%). Case presentation. A 42-year-old Peruvian woman experienced relapse of NHL with uterine localization. She complained at first of abnormal vaginal bleeding and stranguria. The cervical biopsy performed showed a diffuse large B-cell lymphoma in the uterine cervix. The lack of clinical studies on this topic and its rarity make this type of recurrence very difficult to treat. Conclusions. In case of a woman with vaginal bleeding and history of NHL, a disease relapse should always be considered, and a biopsy should be performed to confirm the diagnosis. © 2023, EDRA S.p.A. All rights reserved
Experimental investigation and modelling of T-stubs undergoing large displacements
This paper investigates the development of second (2nd) order effects, arising from geometric and material non-linearities of T-stubs bolted to a rigid support, through a combination of experimental, numerical and analytical approaches. Experimental data is presented for a broad range of T-stub geometries, designed to ensure that significant 2nd order effects always develop, that will complement the existing library of limited test results. Finite element models, incorporating combined tensile (ductile) and shear damage initiation, evolution and failure in both the flange and bolt, are also developed to elucidate how key geometric/material parameters influence the resistance and ductility of T-stubs undergoing large displacement. It will be shown that the restraining effect from the bolt is integral to the activation of catenary action in the flange and the development of a second hardening branch in the tensile response, leading to identification of two new modes of failure that are not currently considered in classical theory or by EC3 (Part 1.8). A mechanical model is formulated to identify the key geometric and material parameters controlling the initiation, and development, of the second hardening branch. Finally, a criterion is proposed to estimate the critical displacement from when 2nd order effects become active
Head-shaking nystagmus in the early stage of unilateral meniere’s disease
OBJECTIVES: The aim of the present study was to evaluate the ability of head-shaking nystagmus (HSNy), evoked after the resolution of a vertigo spell, to predict an imminent crisis in the early stage of Meniere’s disease (MD). MATERIALS and METHODS: A total of 20 patients in the early stage of MD were included in the study. The head-shaking test (HST) was performed twice, during the first visit within 24 h of vertigo spell (T0) and 48 h later (T1). The onset of a new vertigo episode during the 2 weeks following the first visit was recorded in each patient’s medical record. The sensitivity and specificity of HSNy toward predicting a new vertigo episode were calculated. RESULTS: At T0, an evoked ipsilesional HSNy in 15 (75%) patients was observed; in four of them, the HSNy had a biphasic component. The HSNy was present and persistent at T1 in 8 (42.1%) patients; among these cases, 6 patients had ipsilesional HSNy, and 2 patients a contralesional HSNy. None of the patients presented with a biphasic HSNy at T1. Seven (36.8%) patients experienced the recurrence of a vertigo crisis. Among these, 6 patients had ipsilesional HSNy at T1. Only 8 patients with ipsilesional HSNy at T0 did not have recurrence. The sensitivity of the ipsilesional HSNy in predicting the recurrence of vertigo in patients with MD was 100% at T0 and 85.7% at T1. The specificity was 46.6% and 100% at T0 and T1, respectively. CONCLUSION: The HST can be a useful test in the early stages of MD to predict a new vertigo attack
Superscaling and Neutral Current Quasielastic Neutrino-Nucleus Scattering beyond the Relativistic Fermi Gas Model
The superscaling analysis is extended to include quasielastic (QE) scattering
via the weak neutral current of neutrinos and antineutrinos from nuclei. The
scaling function obtained within the coherent density fluctuation model (used
previously in calculations of QE inclusive electron and charge-changing (CC)
neutrino scattering) is applied to neutral current neutrino and antineutrino
scattering with energies of 1 GeV from C with a proton and neutron
knockout (u-channel inclusive processes). The results are compared with those
obtained using the scaling function from the relativistic Fermi gas model and
the scaling function as determined from the superscaling analysis (SuSA) of QE
electron scattering.Comment: 10 pages, 6 figures, published in Phys. Rev.
Embedding Fiber Bragg Grating Sensors in Carbon Composite Structures for Accurate Strain Measurement
Fiber Bragg grating (FBG) sensors written by femtosecond laser pulses in polyamide-coated low bending loss optical fibers are successfully embedded in carbon composite structures, following laminating and light resin molding processes which optimize the size of each ply to address esthetic, drapability, and structural requirements of the final components. The sensors are interrogated by a tunable laser operating at around 1.55 μm, and their response to temperature and strain variations is characterized in a thermally controlled chamber and by bending tests using suspended calibrated loads and a laser scanning system. Experimental results are in good agreement with simulations, confirming that the embedding process effectively overcomes potential issues related to FBG spectral distortion, birefringence, and losses. In particular, the effects of the composite material nonhomogeneity and FBG birefringence are investigated to evaluate their impact on the monitoring capabilities. A bimaterial mechanical beam model is proposed to characterize the orthotropic laminates, pointing out better accuracy in estimating the applied load with respect to the classical homogeneous beam model. A comparative analysis, performed on different instrumented carbon composite samples and supported by theory, points out the repeatability of the FBG sensors' embedding process and the effectiveness of the technology for real-time accurate strain measurement. Based on such measurements, damages and/or changes in local stiffness can be effectively detected, allowing for structural health monitoring (SHM) of composite structures for applications in specific industrial fields such as automotive and aerospace
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