Magnetic ordering and fluctuation in kagome lattice antiferromagnets, Fe and Cr jarosites

Jarosite family compounds, KFe_3(OH)_6(SO_4)_2, (abbreviate Fe jarosite), and KCr_3(OH)_6(SO_4)_2, (Cr jarosite), are typical examples of the Heisenberg antiferromagnet on the kagome lattice and have been investigated by means of magnetization and NMR experiments. The susceptibility of Cr jarosite deviates from Curie-Weiss law due to the short-range spin correlation below about 150 K and shows the magnetic transition at 4.2 K, while Fe jarosite has the transition at 65 K. The susceptibility data fit well with the calculated one on the high temperature expansion for the Heisenberg antiferromagnet on the kagome lattice. The values of exchange interaction of Cr jarosite and Fe jarosite are derived to be J_Cr = 4.9 K and J_Fe = 23 K, respectively. The 1H-NMR spectra of Fe jarosite suggest that the ordered spin structure is the q = 0 type with positive chirality of the 120 degrees configuration. The transition is caused by a weak single-ion type anisotropy. The spin-lattice relaxation rate, 1/T_1, of Fe jarosite in the ordered phase decreases sharply with lowering the temperature and can be well explained by the two-magnon process of spin wave with the anisotropy.Comment: REVTeX, 14 pages with 5 figures. Submitted to Canadian Journal of Physic

Mobilizing agro-biodiversity and social networks to cope with adverse effects of climate and social changes: experiences from Kitui, Kenya

Poster presented at 13th Congress of the International Society of Ethnobiology. Montpellier (France), 20-25 May 201

Music and Architecture: Notes on Experiencing the Convergence of Music and the Built Environment.

D.Arch. Thesis. University of Hawaiʻi at Mānoa 2017

Regularizing effect and local existence for non-cutoff Boltzmann equation

The Boltzmann equation without Grad's angular cutoff assumption is believed to have regularizing effect on the solution because of the non-integrable angular singularity of the cross-section. However, even though so far this has been justified satisfactorily for the spatially homogeneous Boltzmann equation, it is still basically unsolved for the spatially inhomogeneous Boltzmann equation. In this paper, by sharpening the coercivity and upper bound estimates for the collision operator, establishing the hypo-ellipticity of the Boltzmann operator based on a generalized version of the uncertainty principle, and analyzing the commutators between the collision operator and some weighted pseudo differential operators, we prove the regularizing effect in all (time, space and velocity) variables on solutions when some mild regularity is imposed on these solutions. For completeness, we also show that when the initial data has this mild regularity and Maxwellian type decay in velocity variable, there exists a unique local solution with the same regularity, so that this solution enjoys the $C^\infty$ regularity for positive time

Quality of fresh tomato fruit stored inside a solar adsorption cooling storage system as function of low pressure treatment

This paper assessed the physiological loss in weight, total color development and total soluble solids of stored fresh tomato inside solar adsorption cooling storage system. Fresh and treated tomato stored inside solar adsorption cooling storage system at the temperature range of 10°C to 12°C with an average relative humidity level of 80%. The results showed that tomato stored at ambient condition lost weight 5% after seven days of storage then 0.008 MPa treated tomato for 15 minutes, which lost 4.6% after 25 days of storage inside a solar adsorption cooling system. Soluble solids decreased slightly from 7.1% to 6.6% after 25 days storage. The skin brightness L* values of stored tomato at ambient condition increased from 46.1 to 47.9 after seven days of storage at ambient condition and tomato treated with 0.008 MPa treatment for 15 min stored inside solar adsorption cooling storage system decreased from 44.7 to 35.5 after 25 days of storage. The skin redness a* values of stored tomato at ambient condition increased from 18.8 to 20.5 after seven days of storage but tomato treated with 0.008 MPa treatment for 15 min stored inside solar adsorption cooling storage system showed a* values increased from 20.4 to 21.4 after 25 days of storage. The skin yellowness b* value of stored tomato at ambient condition decreased from 10.2 to 7.6 after seven days of storage and tomato treated with 0.008 MPa treatment for 15 min stored inside solar adsorption cooling system decreased from 8.9 to 8.6 after 25 days of storage. These results suggest that the low-cost and energy-saving solar adsorption cooling storage system with low pressure treatment method is useful to keep the fresh tomato fruit quality

Well-posedness of the Viscous Boussinesq System in Besov Spaces of Negative Order Near Index s=−1s=-1

This paper is concerned with well-posedness of the Boussinesq system. We prove that the $n$ ($n\ge2$) dimensional Boussinesq system is well-psoed for small initial data $(\vec{u}_0,\theta_0)$ ($\nabla\cdot\vec{u}_0=0$) either in $({B}^{-1}_{\infty,1}\cap{B^{-1,1}_{\infty,\infty}})\times{B}^{-1}_{p,r}$ or in ${B^{-1,1}_{\infty,\infty}}\times{B}^{-1,\epsilon}_{p,\infty}$ if $r\in[1,\infty]$, $\epsilon>0$ and $p\in(\frac{n}{2},\infty)$, where $B^{s,\epsilon}_{p,q}$ ($s\in\mathbb{R}$, $1\leq p,q\leq\infty$, $\epsilon>0$) is the logarithmically modified Besov space to the standard Besov space $B^{s}_{p,q}$. We also prove that this system is well-posed for small initial data in $({B}^{-1}_{\infty,1}\cap{B^{-1,1}_{\infty,\infty}})\times({B}^{-1}_{\frac{n}{2},1}\cap{B^{-1,1}_{\frac{n}{2},\infty}})$.Comment: 18 page

Numerical modeling of dynamic powder compaction using the Kawakita equation of state

Dynamic powder compaction is analyzed using the assumption that the powder behaves, while it is being compacted, like a hydrodynamic fluid in which deviatoric stress and heat conduction effects can be ignored throughout the process. This enables techniques of computational fluid dynamics such the equilibrium flux method to be used as a modeling tool. The equation of state of the powder under compression is assumed to be a modified version of the Kawakita loading curve. Computer simulations using this model are performed for conditions matching as closely as possible with those from experiments by Page and Killen [Powder Metall. 30, 233 (1987)]. The numerical and experimental results are compared and a surprising degree of qualitative agreement is observed