167 research outputs found
New cosmological solutions and stability analysis in full extended thermodynamics
The Einstein's field equations of FRW universes filled with a dissipative
fluid described by full theory of causal transport equations are analyzed. New
exact solutions are found using a non-local transformations on the nonlinear
differential equation for the Hubble factor. The stability of the de Sitter and
asymptotically friedmannian solutions are analyzed using Lyapunov function
method.Comment: 13 pages, LaTeX 2.09. To be published in International Journal of
Modern Physics
Crop Coefficient of Tomato under Deficit Irrigation and Mulch Practices at Kano River Irrigation Project, Nigeria
This work determined the effects of deficit irrigation and mulching practices on crop coefficient (Kc) of tomato in the Kano River Irrigation Project (KRIP) Kadawa, Kano, Nigeria. Experiments comprised of four levels of water application depths (40, 60, 80, and 100% of weekly reference evapotranspiration) and four levels of mulching (No-Mulch (NM), Rice-Straw-Mulch (RSM), Wood-Shaving-Mulch (WSM) and White-Polyethylene-Mulch (WPM)) was conducted to examine changes in Kc value. The mean Kc values (early, developmental, mid and late stages) of fully irrigated treatments were 0.70, 0.81, 1.07 and 0.78; 0.64, 0.76, 0.99 and 0.71; 0.60, 0.73, 0.94 and 0.69; and 0.53, 0.66, 0.86 and 0.62 for NM, RSM, WSM and WPM respectively while that of deficit irrigation ranged from 0.17 to 1.13 across the treatments, noting that the highest Kc was observed under NM treatments. Statistical analysis reveals that the effect of various levels of irrigation and mulching practices on Kc of tomato was highly significant at P<0.05 level of significance with a high mean value of 1.13 obtained at I100 and NM respectively. It was concluded to encourage tomato farmers in KRIP to adopt the use of their rice straw for mulching cum deficit irrigation (20%) towards conserving irrigation water for sustainability. Also, results obtained from this study can be used as a guide to farmers in irrigating tomato crop and to engineers in the design of irrigation systems
New antineutrino energy spectra predictions from the summation of beta decay branches of the fission products
In this paper, we study the impact of the inclusion of the recently measured
beta decay properties of the Tc, Mo, and
Nb nuclei in an updated calculation of the antineutrino energy spectra
of the four fissible isotopes U, and Pu. These
actinides are the main contributors to the fission processes in Pressurized
Water Reactors. The beta feeding probabilities of the above-mentioned Tc, Mo
and Nb isotopes have been found to play a major role in the component
of the decay heat of Pu, solving a large part of the
discrepancy in the 4 to 3000\,s range. They have been measured using the Total
Absorption Technique (TAS), avoiding the Pandemonium effect. The calculations
are performed using the information available nowadays in the nuclear
databases, summing all the contributions of the beta decay branches of the
fission products. Our results provide a new prediction of the antineutrino
energy spectra of U, Pu and in particular of U for
which no measurement has been published yet. We conclude that new TAS
measurements are mandatory to improve the reliability of the predicted spectra.Comment: 10 pages, 2 figure
Total Absorption Spectroscopy Study of Rb Decay: A Major Contributor to Reactor Antineutrino Spectrum Shape
The antineutrino spectra measured in recent experiments at reactors are
inconsistent with calculations based on the conversion of integral beta spectra
recorded at the ILL reactor. Rb makes the dominant contribution to the
reactor spectrum in the 5-8 MeV range but its decay properties are in question.
We have studied Rb decay with total absorption spectroscopy. Previously
unobserved beta feeding was seen in the 4.5-5.5 region and the GS to GS feeding
was found to be 87.5(25)%. The impact on the reactor antineutrino spectra
calculated with the summation method is shown and discussed.Comment: 6 pages, 3 figure
Cosmological particle production, causal thermodynamics, and inflationary expansion
Combining the equivalence between cosmological particle creation and an
effective viscous fluid pressure with the fact that the latter represents a
dynamical degree of freedom within the second-order Israel-Stewart theory for
imperfect fluids, we reconsider the possibility of accelerated expansion in
fluid cosmology. We find an inherent self-limitation for the magnitude of an
effective bulk pressure which is due to adiabatic (isentropic) particle
production. For a production rate which depends quadratically on the Hubble
rate we confirm the existence of solutions which describe a smooth transition
from inflationary to noninflationary behavior and discuss their interpretation
within the model of a decaying vacuum energy density. An alternative
formulation of the effective imperfect fluid dynamics in terms of a minimally
coupled scalar field is given. The corresponding potential is discussed and an
entropy equivalent for the scalar field is found.Comment: 16 pages, revtex file, submitted to Phys. Rev.
Long-term impact of West African food system responses to COVID-19.
The COVID-19 pandemic continues to impact health and livelihoods in West Africa. Exposure of food system fragilities by the pandemic presents the opportunity for regional-specific reforms to deliver healthy diets for all and promote resilience to future shocks
Earnings management and audit quality:stakeholders’ perceptions
This paper examines the perceptions of Libyan Commercial Banks’ (LCBs) stakeholders regarding the role of the external auditor in relation to earnings management (EM). A total of 28 semi-structured interviews were carried out with a range of LCB stakeholders comprising preparers of financial statements, users, regulators and academics. A questionnaire survey of stakeholders which yielded 102 Responses (response rate 53%) was also carried out. A variety of views were held which varied to some extent according to stakeholder group. A widely held perception amongst interviewees was that the auditor has the ability to detect EM practices but may not be able to prevent it. However questionnaire respondents were, in aggregate, more confident of the auditor’s ability to deter EM due to the influence of the audit report. The paper provides insights into stakeholders’ perceptions of the quality of bank audits. The findings are of particular relevance to regulators, and specifically, the Central Bank of Libya. Perceptions of audit quality raise questions about its guidance and regulations especially in connection with audit firm rotation. Perceptions of audit quality, and therefore, of the credibility of financial statements should be of interest to all stakeholders. The importance of the banking sector for society has been amply demonstrated in recent years. A well-functioning audit function is a key component of its regulation. To the best of our knowledge, this paper is the first to examine issues related to banks’ audit quality and audit firm rotation in Libya
Total absorption spectroscopy study of the beta decay of Br-86 and Rb-91
The beta decays of Br-86 and Rb-91 have been studied using the total absorption spectroscopy technique. The radioactive nuclei were produced at the Ion Guide Isotope Separator On-Line facility in Jyvaskyla and further purified using the JYFLTRAP. Br-86 and Rb-91 are considered to be major contributors to the decay heat in reactors. In addition, Rb-91 was used as a normalization point in direct measurements of mean gamma energies released in the beta decay of fission products by Rudstam et al. assuming that this decaywas well known from high-resolution measurements. Our results show that both decays were suffering from the Pandemonium effect and that the results of Rudstam et al. should be renormalized. The relative impact of the studied decays in the prediction of the decay heat and antineutrino spectrum from reactors has been evaluated.Peer reviewe
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