Exact two-holon wave functions in the Kuramoto-Yokoyama model

We construct the explicit two-holon eigenstates of the SU(2) Kuramoto-Yokoyama model at the level of explicit wave functions. We derive the exact energies and obtain the individual holon momenta, which are quantized according to the half-Fermi statistics of the holons.Comment: 16 pages revte

Lattice rules with random nn achieve nearly the optimal O(n−α−1/2)\mathcal{O}(n^{-\alpha-1/2}) error independently of the dimension

We analyze a new random algorithm for numerical integration of $d$-variate functions over $[0,1]^d$ from a weighted Sobolev space with dominating mixed smoothness $\alpha\ge 0$ and product weights $1\ge\gamma_1\ge\gamma_2\ge\cdots>0$, where the functions are continuous and periodic when $\alpha>1/2$. The algorithm is based on rank-$1$ lattice rules with a random number of points~$n$. For the case $\alpha>1/2$, we prove that the algorithm achieves almost the optimal order of convergence of $\mathcal{O}(n^{-\alpha-1/2})$, where the implied constant is independent of the dimension~$d$ if the weights satisfy $\sum_{j=1}^\infty \gamma_j^{1/\alpha}<\infty$. The same rate of convergence holds for the more general case $\alpha>0$ by adding a random shift to the lattice rule with random $n$. This shows, in particular, that the exponent of strong tractability in the randomized setting equals $1/(\alpha+1/2)$, if the weights decay fast enough. We obtain a lower bound to indicate that our results are essentially optimal. This paper is a significant advancement over previous related works with respect to the potential for implementation and the independence of error bounds on the problem dimension. Other known algorithms which achieve the optimal error bounds, such as those based on Frolov's method, are very difficult to implement especially in high dimensions. Here we adapt a lesser-known randomization technique introduced by Bakhvalov in 1961. This algorithm is based on rank-$1$ lattice rules which are very easy to implement given the integer generating vectors. A simple probabilistic approach can be used to obtain suitable generating vectors.Comment: 17 page

Melting and freezing of argon in a granular packing of linear mesopore arrays

Freezing and melting of Ar condensed in a granular packing of template-grown arrays of linear mesopores (SBA-15, mean pore diameter 8 nanometer) has been studied by specific heat measurements C as a function of fractional filling of the pores. While interfacial melting leads to a single melting peak in C, homogeneous and heterogeneous freezing along with a delayering transition for partial fillings of the pores result in a complex freezing mechanism explainable only by a consideration of regular adsorption sites (in the cylindrical mesopores) and irregular adsorption sites (in niches of the rough external surfaces of the grains, and at points of mutual contact of the powder grains). The tensile pressure release upon reaching bulk liquid/vapor coexistence quantitatively accounts for an upward shift of the melting/freeezing temperature observed while overfilling the mesopores.Comment: 4 pages, 4 figures, to appear as a Letter in Physical Review Letter

Apiculture commodity development in Goma District: experiences from IPMS

Goma is endowed with different flora and adequate moisture which favors honey production. As a result, bee farmers started producing honey since time immemorial using traditional hives, mostly made of bamboo. Improved hive production in the Woreda started in 1987 among cooperatives formed during the military regime. In 2007, apiculture was identified as one of the priority commodity for Goma PLW through participatory priority commodities identification. Major constraints identified were shortage and/or substandard inputs supply, poor quality honey, lack of market, skill and knowledge limitations of bee farmers and technical staff. To address the challenges, value-chain development approach was exercised and in this regard the following developments were recorded. One interested honey shop was upgraded to become an apiculture input shop in Agaro town with financial assistance from OCSSCo/IPMS and technical assistance from the District Livestock Development and Production Agency (LDPA) and IPMS. This input shop supplied considerable inputs to bee farmers who also provide commercial services for their neighbours. One of the important inputs delivered to bee farmers was imported honey extractor but less demand was observed due to its high price. Moreover, one interested honey producers association named Wojin Gudina Honey Producers Association was formed and got legal identity. The association is expected to play market regulatory role, quality assurance, do bulking of member produce as well as non members to maintain bargaining power. About 44 interested farmers and 12 technical staff received skill and knowledge upgrading training and in this regard Jima University (JU) played a big role. More focus was given to transforming traditional to transitional hives (Kenya Top Bar), which was a change for the frame hives (modern hives) which had been introduced before. Twenty interested farmers received 123 transitional hives in Acha Afeta PA through credit and also transitional hive use has shown significant increase within and outside interested farmers in the last two years. To address market constraints, an effort was made to link honey producer with honey processing and export enterprises and in this regard Beza Mar honey processing and exporting enterprise has already started the process to buy Goma honey. Prior to this, an attempt was also made with another commercial processor but was not successful. The effects of various interventions are just emerging and are expected to come to full fruition over time. A household (HH) survey conducted by the project indicated however that adopters of improved apiculture technologies produced in 2008, on average, about birr 3,400 of honey per year compared to birr 225 by traditional bee keepers. Major lessons learned include that the intervention stimulated increased demand for improved hives and better use of existing hives. As compared to other Districts, involvement of private sector in the sale of accessories for improved bee hives and honey processing is emerging. Most of the honey produced from framed hives is extracted using locally made crude extractors with less or no food graded approval and also less quality honey. These extractors are operated commercially by private individuals, but require further technical support to improve quality. The development of a quality honey market is just emerging, however as indicated in the prices, no clear price incentive for quality honey is observed yet, probably because of the still relatively small volume entering into this market segment. Another indication of the still limited demand for clear honey is the increase in the numbers of traditional hives in the last two to three years

Fruit commodity development in Goma District through farmer-based improved fruit seedling supply system: Experiences from IPMS

In Goma, fruits considerably contribute in improving the nutritional status and income of the community. However, its production and productivity has been very low. The objective of this case study is to share best practices and lessons learned from farmer-based improved fruit seedlings supply system that could contribute to enhance fruit production in Goma Pilot Learning Woreda (PLW). The assessment result highlights that fruits production in Goma is a recent phenomenon and all fruit farmers got their first planting material from unknown sources and hence agronomic and cultural practices required for each fruit type is less known. Consequently, constraints such as extended periods to fruiting, failure to set fruits, unmanageable fruit tree height, diseases and pests, low yield, etc. are very common. Above all, introduction of various fruits to Goma Woreda was made much earlier than the institutional, skill and knowledge of the OoARD (the Office of Agriculture and Rural development) staff handling them. In addition, key technical limitation to fruits development identified through participatory commodity development approach includes scarcity of improved planting materials, large canopies, poor quality fruits, long time to maturity, among others. IPMS and OoARD initiated farmers-based improved fruits planting materials multiplication and distribution system in trying to solve the problem. Six model farmers (3 female, 3 male) were trained and engaged in grafting avocado and produced 2,052 grafted avocado seedlings from internationally known varieties such as Hass, Ettinger, and Fuerte which were sold to 163 households in 28 Peasant Associations (Pas) at Birr 25 per seedling. The farmers earned Birr 42,000 among them in total. Also mother trees of Hass, Ettinger and Fuerte were established in each model farmer’s plot for sustainable scion supply. Taking the advantage of this successful demonstration, OoARD started a scaling out program by including 3 additional model farmers. The 9 model farmers have now raised 17,000 avocado and mango root stock seedling at their own cost amounting to Birr 85,000 which will be ready for grafting starting from January 2010. In addition 3 copy farmers in Kilole PA are also engaged in improved fruits seedlings production. The effort demonstrated that farmers could be good sources for technology multiplication and distribution, which has been a key challenge in technology uptake not only for fruits but for many other commodities in Ethiopia