Gamow–Teller (GT) transitions are the most common weak interaction processes of spin–isospin (
σ
τ
) type in atomic nuclei. They are of interest not only in nuclear physics but also in astrophysics; ...they play an important role in supernovae explosions and nucleosynthesis. The direct study of weak decay processes, however, gives relatively limited information about GT transitions and the states excited via GT transitions (GT states);
β
decay can only access states at excitation energies lower than the decay
Q
-value, and neutrino-induced reactions have very small cross-sections. However, one should note that
β
decay has a direct access to the absolute GT transition strengths
B
(GT) from a study of half-lives,
Q
β
-values and branching ratios. They also provide information on GT transitions in nuclei far-from-stability. Studies of
M
1
γ
transitions provide similar information. In contrast, the complementary charge-exchange (CE) reactions, such as the (
p
,
n
) or (
3He,
t
) reactions at intermediate beam energies and 0°, can selectively excite GT states up to high excitation energies in the final nucleus. It has been found empirically that there is a close proportionality between the cross-sections at 0° and the transition strengths
B
(GT) in these CE reactions. Therefore, CE reactions are useful tools to study the relative values of
B
(GT) strengths up to high excitation energies. In recent (
3He,
t
) measurements, one order-of-magnitude improvement in the energy resolution has been achieved. This has made it possible to make one-to-one comparisons of GT transitions studied in CE reactions and
β
decays. Thus GT strengths in (
3He,
t
) reactions can be normalised by the
β
-decay values. In addition, comparisons with closely related
M
1
transitions studied in
γ
decay or electron inelastic scattering (
e
,
e
′
), and furthermore with “spin”
M
1
transitions that can be studied by proton inelastic scattering (
p
,
p
′
) have now been made possible. In these comparisons, the isospin quantum number
T
and associated symmetry structure in the same mass
A
nuclei (isobars) play a key role. Isospin symmetry can extend our scope even to the structures of unstable nuclei that are far from reach at present unstable beam factories.
In this review we will present the results of recent
β
-decay studies using the total absorption technique that cover topics of interest for applications, nuclear structure and astrophysics. The ...decays studied were selected primarily because they have a large impact on the prediction of (a) the decay heat in reactors, important for the safety of present and future reactors and (b) the reactor electron anti-neutrino spectrum, of interest for particle/nuclear physics and reactor monitoring. For these studies the total absorption technique was chosen, since it is the only method that allows one to obtain
β
-decay probabilities free from a systematic error called the Pandemonium effect. The total absorption technique is based on the detection of the
γ
cascades that follow the initial
β
decay. For this reason the technique requires the use of calorimeters with very high
γ
detection efficiency. The measurements presented and discussed here were performed mainly at the IGISOL facility of the University of Jyväskylä (Finland) using isotopically pure beams provided by the JYFLTRAP Penning trap. Examples are presented to show that the results of our measurements on selected nuclei have had a large impact on predictions of both the decay heat and the anti-neutrino spectrum from reactors. Some of the cases involve
β
-delayed neutron emission thus one can study the competition between
γ
- and neutron-emission from states above the neutron separation energy. The
γ
-to-neutron emission ratios can be used to constrain neutron capture (n,
γ
) cross sections for unstable nuclei of interest in astrophysics. The information obtained from the measurements can also be used to test nuclear model predictions of half-lives and Pn values for decays of interest in astrophysical network calculations. These comparisons also provide insights into aspects of nuclear structure in particular regions of the nuclear chart.
Cocoa cultivation is of considerable economic and social importance to the Amazonas region and is commonly associated with forest species in the region. However, the diversification level and ...composition of cacao agroforestry systems in Peru are poorly understood. The objective of this study is, therefore, to describe the diversity of tree species in cocoa AFS by plantation age. Accordingly, the number of species of 15 plots covering a total of 1.5 hectares was recorded. Moderately low levels of tree species diversity were reported (H' ranged 0.89-1.45). In total 17 species were reported throughout the study area. The most abundant botanical family was represented by a single Musa sp. species. The dissimilarity indices show a moderate similarity between the age ranges evaluated (over 62%). Additionally, the IVI indicates that the most important species are used for food and timber apart from providing shade, additionally major of this species are introduced intentionally for the farmers. Based on the observations, it may be concluded that the farmer's interest in obtaining further benefits from the plot, mostly economic benefits affect the diversification of cocoa agroforestry systems.
It is estimated that the development of a new anticancer agent costs US$800 million to 1 billion and takes more than a decade between conception and approval.1 However, 90% of novel antineoplastic ...drugs fail in the clinic despite evidence of antitumor efficacy in classical preclinical models.2 This raises serious concerns as to whether such models are predictive of drug efficacy in humans, particularly in the current era of new targeted therapies, and supports the development of alternative approaches.
Clinical Pharmacology & Therapeutics (2009); 85, 2, 217–221 doi:10.1038/clpt.2008.200
A new summation method model of the reactor antineutrino energy spectrum is presented. It is updated with the most recent evaluated decay databases and with our total absorption gamma-ray ...spectroscopy measurements performed during the last decade. For the first time, the spectral measurements from the Daya Bay experiment are compared with the antineutrino energy spectrum computed with the updated summation method without any renormalization. The results exhibit a better agreement than is obtained with the Huber-Mueller model in the 2-5 MeV range, the region that dominates the detected flux. A systematic trend is found in which the antineutrino flux computed with the summation model decreases with the inclusion of more pandemonium-free data. The calculated flux obtained now lies only 1.9% above that detected in the Daya Bay experiment, a value that may be reduced with forthcoming new pandemonium-free data, leaving less room for a reactor anomaly. Eventually, the new predictions of individual antineutrino spectra for the ^{235}U, ^{239}Pu, ^{241}Pu, and ^{238}U are used to compute the dependence of the reactor antineutrino spectral shape on the fission fractions.
In this paper, Schur polynomials are used to provide a bidiagonal decomposition of polynomial collocation matrices. The symmetry of Schur polynomials is exploited to analyze the total positivity on ...some unbounded intervals of a relevant class of polynomial bases. The proposed factorization is used to achieve relative errors of the order of the unit round-off when solving algebraic problems involving the collocation matrix of relevant polynomial bases, such as the Hermite basis. The numerical experimentation illustrates the accurate results obtained when using the findings of the paper.
The effect of dietary treatment (CTRL, control; VIT-E, 500mgkg−1 vitamin E; GSE, 50mg grape seed extract kg−1; GP-5, 5% dried red grape pomace kg−1) on shelf life of lamb meat was studied. After ...slaughter (27kg LBW), m. longissimus thoracis et lumborum was sliced, packaged under modified atmosphere (80:20%/O2:CO2) and stored in retail conditions for 14days. At each sampling day (0, 4, 7, 11, 14), microbiological, physico-chemical and sensory characteristics were analysed. Meat from VIT-E presented lower microbial counts than CTRL, GSE and GP-5, without differences between polyphenol treatments (GSE and GP-5) and CTRL. Vitamin E reduced meat discoloration and lipid oxidation (TBARS values) from day 7 with respect to the other treatments. Although not significant, an improvement in TBARS values of about 20% was observed for GSE and GP-5, compared with CTRL, from day 7 of storage. VIT-E dietary treatment was more effective in preventing sensory spoilage than the other treatments.
•The effect of grape pomace on lamb meat shelf life was studied.•Meat from vitamin E lambs showed lower microbial counts than lambs fed grape pomace.•Vitamin E was more effective in preventing sensory spoilage than grape pomace.•The use of grape pomace decreased lipid oxidation by about 20%.
Forty-eight Churra ewes and their suckling lambs were assigned to four dietary treatments: control (CTRL), VIT-E (500 mg kg-1 TMR vitamin E), GP-5 (5% grape pomace) and GP-10 (10% grape pomace). ...After slaughter (11.5 kg live weight), longissimus muscle of lambs was sliced, packaged under modified atmosphere (80,20%/O 2:CO 2) and stored in retail conditions. At each sampling point (0, 3, 7, 10, 14 days), microbiological, physicochemical and sensory characteristics were analysed. Vitamin E and GP-5 were found to be effective (p < 0.05) at preventing enterobacteria growth as of day 10. After day 10, vitamin E and grape pomace in the ewe's supplementation reduced metmyoglobin (p < 0.05) lipid oxidation (p < 0.05) and sensory spoilage throughout the storage period. An effect of the grape pomace dosage was observed, with the supplementation at 5% being more effective. Therefore, we can conclude that grape pomace was just as effective as vitamin E in preventing spoilage during retail storage.
•Addition VIT-E and grape pomace to ewe diet affects shelf life of suckling lamb meat packaged and stored in retail conditions.•Ewes fed VIT-E and grape pomace delayed myoglobin, lipid oxidation and sensory spoilage of suckling lamb meat during storage.•Grape pomace was as effective as vitamin E in extending the shelf life of lamb meat.•Supplementation of 5% grape pomace in ewe diets was more effective at extending shelf life of suckling lamb meat than 10%
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•Chitosan can be incorporated successfully to the hybrid silicon network.•The addition of chitosan and TEOS modulate osteoinductive Silicon release.•Chitosan containing formulations ...show antibacterial properties and adhere well to metal substrates.
To avoid dental implant-related infections and to promote the osseointegration of titanium implants, the application of silicon and chitosan containing coatings is proposed. Silicon is a well-known osteogenic element and chitosan was selected to confer the antibacterial properties. The synthesis of hybrid silica-chitosan coatings using the sol-gel process is presented and the characterization using 29Si-NMR to verify the correct formation of the network is discussed. The 13C NMR spectroscopy was used to confirm the covalent union between chitosan and the silicon network. Hydrolytic degradation and silicon release studies showed the effective silicon release from the hybrids and, hence, the possibility to promote bone formation. The introduction of different amounts of chitosan and tetraethyl orthosilicate (TEOS) modulated the Si release. The analysis of cell cultures in vitro demonstrated that the hybrid coatings were not cytotoxic and promoted cell proliferation on their surfaces. The coatings containing 5%–10% chitosan had substantial antibacterial properties.
In this paper an accurate method to construct the bidiagonal factorization of collocation and Wronskian matrices of Jacobi polynomials is obtained and used to compute with high relative accuracy ...their eigenvalues, singular values and inverses. The particular cases of collocation and Wronskian matrices of Legendre polynomials, Gegenbauer polynomials, Chebyshev polynomials of the first and second kind and rational Jacobi polynomials are considered. Numerical examples are included.
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