1,103 research outputs found
Seed germination report for Limonium merxmuelleri subsp. merxmuelleri (Plumbaginaceae)
The present report illustrates the first germination data of Limonium merxmuelleri subsp. merxmuelleri, a pioneer species of mine waste materials of Iglesiente region (South-West Sardinia). After harvesting, seeds were subjected to germination tests at the Sardinian Germplasm Bank (BG-SAR). The results show a high germination capability and germination rate at each tested temperature, with a slight germination reduction at the highest temperature (25°C) that simulates the aridity of the summer period
Effect of Control Plot Density, Control Plot Arrangement, and Assumption of Random or Fixed Effects on Nonreplicated Experiments for Germplasm Screening Using Spatial Models
Early generation selection experiments typically involve several hundred to thousands of lines. Various systematic and statistical techniques have been developed to increase effectiveness and efficiencies in such experiments, including the development and application of spatial statistical models. In this study, mixed model equations were used to provide least squares means (LSMEANs) and best linear unbiased predictors (BLUPs) and compare selection effectiveness and efficiencies to observed (Y) and true values in simulated experiments varying in size (10 X 10, 20 X 20 and 30 X 30 grids), control plots densities (0, 5, 10, 20, and 50%), control plot arrangements (high, medium, and low A-optimality), and spatial range of influence (short and long). Results were similar for all grid sizes. In experiments in which the simulated land areas were highly variable (short range), none of the predictors, Y, LSMEAN, or BLUP, were very effective in identifying the true superior genotypes. When the simulated land areas were less variable (long range), use of BLUPs consistently resulted in the highest proportion of true top ranking genotypes identified across all control plot densities, while using the observed values consistently resulted in identification of the lowest proportion of the true top ranking genotypes. Effectiveness of LSMEANs was dependent on control plot density and arrangements.Use of BLUPs for early generation germplasm screening experiments should result in a high effectiveness in selecting truly superior germplasm and high efficiency because of the ability to account for spatial variability with the use of few or no control plots
Recanalization of the Native Artery in Patients with Bypass Failure
Our objective was to evaluate the possible role
of endovascular recanalization of occluded native artery
after a failed bypass graft in the case of either acute or
chronic limb-threatening ischemia otherwise leading to
amputation. In a single-center retrospective clinical analysis,
from January 2004 to March 2007 we collected 31
consecutive high-surgical-risk patients (32 limbs) with
critical limb ischemia following late ([30 days after surgery)
failure of open surgery bypass graft reconstruction.
All patients deemed unfit for surgery underwent tentative
endovascular recanalization of the native occluded arterial
tract. The mean follow-up period was 24 (range, 6–42)
months. Technical success was achieved in 30 (93.7%) of
32 limbs. The cumulative primary assisted patency calculated
by Kaplan–Meyer analysis was 92% and 88%,
respectively, at 12 and 24 months. The limb salvage rate
approached 90% at 30 months. In conclusion, our experience
shows the feasibility of occluded native artery endovascular
recanalization after a failed bypass graft, with
optimal results in terms of midterm arterial patency and
limb salvage. Our opinion is that successful recanalization
of the arterial tract previously considered unsuitable for
endovascular approach is allowed by improved competency
and experience of vascular specialists, as well as the
advances made in catheter and guidewire technology. This
group of patients would previously have been relegated to
repeat bypass grafts, with their inherently inferior patency
and recognized added technical demands. We recognize
previous surgical native artery disconnection and lack of
pedal runoff to be the main cause of technical failure.
Keywords Native artery Bypass failure
Endovascular recanalizatio
Post Quantum Cryptography from Mutant Prime Knots
By resorting to basic features of topological knot theory we propose a
(classical) cryptographic protocol based on the `difficulty' of decomposing
complex knots generated as connected sums of prime knots and their mutants. The
scheme combines an asymmetric public key protocol with symmetric private ones
and is intrinsecally secure against quantum eavesdropper attacks.Comment: 14 pages, 5 figure
Modelling Li+ Ion Battery Electrode Properties
We formulated two detailed models for an electrolytic cell with particulate electrodes based on a lithium atom concentration dependent Butler-Volmer condition at the interface between electrode particles and the electrolyte. The first was based on a dilute-ion assumption for the electrolyte, while the second assumed that Li ions are present in excess.
For the first, we used the method of multiple scales to homogenize this model over the microstructure, formed by the small lithium particles in the electrodes.
For the second, we gave rigorous bounds for the effective electrochemical conductivity for a linearized case.
We expect similar results and bounds for the "full nonlinear problem" because variational results are generally not adversely affected by a sinh term.
Finally we used the asymptotic methods, based on parameters estimated from the literature, to attain a greatly simplified one-dimensional version of the original homogenized model. This simplified model accounts for the fact that diffusion of lithium atoms within individual electrode particles is relatively much faster than that of lithium ions across the whole cell so that lithium ion diffusion is what limits the performance of the battery. However, since most of the potential drop occurs across the Debye layers surrounding each electrode particle, lithium ion diffusion only significantly affects cell performance if there is more or less complete depletion of lithium ions in some region of the electrolyte which causes a break in the current flowing across the cell. This causes catastrophic failure. Providing such failure does not occur the potential drop across the cell is determined by the concentration of lithium atoms in the electrode particles. Within each electrode lithium atom concentration is, to leading order, a function of time only and not of position within the electrode. The depletion of electrode lithium atom concentration is directly proportional to the current being drawn off the cell. This leads one to expect that the potential of the cell gradually drops as current is drawn of it.
We would like to emphasize that all the homogenization methods employed in this work give a systematic approach for investigating the effect that changes in the microstructure have on the behaviour of the battery. However, due to lack of time, we have not used this method to investigate particular particle geometries
Effect of storage conditions on seed germination of eigTyrrhenian endemic vascular plant species of conservation interest
The conservation of endemic and endangered plant species is of great interest to the scientific and research community. In this frame, seed banks play a crucial role when biodiversity preservation and climate change are considered. The study of seed viability and germination during storage conditions provides basic and useful information to ensure successful ex situ conservation. The aim of this study was to evaluate whether storage time and conditions (i.e., base collection at -25°C and active collection at +5°C) affect seed germination in the long term. For these purposes, eight Tyrrhenian endemic vascular plant species (mostly endangered) with orthodox seeds were studied: Brassica insularis, Centranthus amazonum, Dianthus morisianus, Digitalis purpurea var. gyspergerae, Ferula arrigonii, Helicodiceros muscivorus, Iberis integerrima and Verbascum plantagineum. These species were stored in the Sardinian Germplasm Bank (BG-SAR) at -25°C and at +5°C for a time ranging from 2 to 12 years. Germination tests were carried out following the optimal conditions reported in the literature for each species. The results showed, in general terms, the high seed germination capacity of all species stored at both conditions; regarding the time of seed storage, germination in some tested species (such as B. insularis and C. amazonum) slightly decreased over time. We argued that seed dehydration, low seed moisture content during storage and the use of hermetic glass containers can be considered key factors for long-term conservation of these orthodox seeds. In conclusion, this study showed that the conservation of these endemic species is ensured by seed bank storage, according to the general assumption that seed longevity depends on seed lot quality, on well-sealed storage containers and conditions before and during storage
Review on imidacloprid diffusion route and a case study: from apple orchard to the honey bee colony matrices
Honey bees play a pivotal role in natural and rural ecosystems by providing human and animal food sources through pollination services. However, in cultivated areas, they can be exposed to the chemicals utilized for crop protection. Neonicotinoid insecticides can adversely affect honey bee colonies impairing their survival, immunity and biological activities at lethal and sublethal doses. For this reason, neonicotinoids, together with other stress factors, like pathogens (e.g. viruses and Varroa mites), climate change and food shortage, are considered one of the causes of worldwide colony losses. Nevertheless, the natural way of entry and diffusion of these pesticides in field colonies is not completely clear. Here, we wanted to fill this gap by studying the diffusion route of imidacloprid and its metabolites by analysing different matrices collected from honey bee colonies used for pollination of apple orchards, in the framework of applied Integrated Pest Management strategies. Pollen, honey bees, honey, royal jelly, bee wax and bee bread were sampled from 6 honey bee colonies placed in two different apple orchards before blooming, exposed to chemicals application and removed from the site after that. Samples were analysed using a liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) and gas chromatography-tandem mass spectrometry (GC-MS/MS) in order to detect imidacloprid, olefin imidacloprid and 5-hydroxy imidacloprid. The results demonstrate that the primary way of entrance of imidacloprid was the pollen transported by foragers, while the main accumulation matrices were bee bread, honey and wax. These findings allow us to hypothesize that the accumulation of this insecticide, especially in bee bread, the main larval food, could potentially impact negatively on honey bee wellbeing at the adult stage. Moreover, our data could implement the honey bee colony simulato
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