Concentration-adjustable micromixer using droplet injection into a microchannel

A novel micromixing technique that exploit a thrust of droplets into the mixing interface is developed. The technique enhances the mixing by injecting immiscible droplets in a mixing channel and the methodology enables a control of the mixing level simply by changing the droplet injection frequency. We experimentally characterize the mixing performance with various droplet injection frequencies, channel geometries, and diffusion coefficients. Consequently, it is revealed that the mixing level increases with the injection frequency, the droplet-diameter-to-channel-width ratio, and the diffusion coefficient. Moreover, the mixing level is found to be a linear function of the droplet volume fraction in the mixing section. The results suggest that the developed technique can produce a large amount of sample solution whose concentration is arbitrary and precisely controllable with a simple and stable operation.Comment: 12 + 3 pages, 6 + 4 figure

Livestock Transactions as Coping Strategies in Zambia:New Evidence from High-Frequency Panel Data

This study re-examines the buffer stock hypothesis regarding livestock by taking into account differences in wealth level, asset types, and periods after a shock. This paper takes advantage of a unique panel data set of agricultural households in Southern Province, Zambia. The data were collected by weekly interviews of 48 sample households from November 2007 to December 2009, covering two crop years in which an unusually heavy rainfall event took place. If we consider delayed responses to the heavy rain shock, our econometric analyses support the buffer stock hypothesis for cattle as well as small livestock. Overall, this paper suggests that conventional annual data sets used by existing literature may miss the period-dependent transactions of assets after a shock.Asset smoothing, Buffer stock, Weather risk, Livestock, Sub-Saharan Africa

Basis Risk and Low Demand for Weather Index Insurance

Natural Resource Economics Discussion Papers are preliminary research reports by members of the GSA-NRE Kyoto University circulated for comments and suggestions. They have not been externally peer-reviewed or been subject to the review by the editorial board.Basis risk --an imperfect correlation between an aggregate index and idiosyncratic crop damage-- has been widely recognized as a major impediment to embracing index insurance. However, empirical evidence is still scarce because of the difficulty in its direct measurement. In this study, we estimate the impact of the basis risk on demand for a rainfall index insurance product using household survey data from rural Zambia. First, we develop a simple model of insurance demand to motivate our econometric specifications. Then, we quantify the basis risk for each surveyed household with past rainfall data at the plot-level. Exploiting changes in insurance design across years, we use within-household variations in the basis risk to estimate its impact. Empirical results illustrate that the basis risk has significant and adverse effects on insurance demand. Despite its statistical significance, our results also suggest that minimizing the basis risk would not yield enough economic benefits to offset the associated costs

Livestock Transactions as Coping Strategies in Zambia: New Evidence from High-Frequency Panel Data

This study re-examines the buffer stock hypothesis regarding livestock by taking into account differences in wealth level, asset types, and periods after a shock. This paper takes advantage of a unique panel data set of agricultural households in Southern Province, Zambia. The data were collected by weekly interviews of 48 sample households from November 2007 to December 2009, covering two crop years in which an unusually heavy rainfall event took place. If we consider delayed responses to the heavy rain shock, our econometric analyses support the buffer stock hypothesis for cattle as well as small livestock. Overall, this paper suggests that conventional annual data sets used by existing literature may miss the period-dependent transactions of assets after a shock.Asset Smoothing, Buffer Stock, Weather Risk, Livestock, Sub-Saharan Africa

Soliton Trap in Strained Graphene Nanoribbons

The wavefunction of a massless fermion consists of two chiralities, left-handed and right-handed, which are eigenstates of the chiral operator. The theory of weak interactions of elementally particle physics is not symmetric about the two chiralities, and such a symmetry breaking theory is referred to as a chiral gauge theory. The chiral gauge theory can be applied to the massless Dirac particles of graphene. In this paper we show within the framework of the chiral gauge theory for graphene that a topological soliton exists near the boundary of a graphene nanoribbon in the presence of a strain. This soliton is a zero-energy state connecting two chiralities and is an elementally excitation transporting a pseudospin. The soliton should be observable by means of a scanning tunneling microscopy experiment.Comment: 7 pages, 4 figure

Vitellogenin gene of the silkworm, Bombyx mori: Structure and sex-dependent expression

AbstractVitellogenin of Bombyx mori is a precursor of major yolk protein synthesized in the female fat body at larval—pupal ecdysis. The gene for B. mori vitellogenin is composed of seven exons interspersed by six introns. Developmental profile of the primary transcript of the gene indicated that the biosynthesis of B. mori vitellogenin is regulated transcriptionally in a sex- and stage-dependent manner in the fat body. The Arg-X-Arg-Arg sequence, which conforms to the recognition site of mammalian furin, occurs in a region just upstream of the putative proteolytic cleavage site of B. mori previtellogenin

Colloidal Composite of Hydroxylated Fullerenes and Gold Nanoparticles

Since bare gold nanoparticles are unstable, they have to be stabilized by protecting with ligands, stabilizing with polymers or immobilizing on solids. Properties of gold nanoparticles depend on the design of their protecting ligands

The Molecular Mechanism Underlying Continuous Exercise Training-Induced Adaptive Changes of Lipolysis in White Adipose Cells

Physical exercise accelerates the mobilization of free fatty acids from white adipocytes to provide fuel for energy. This happens in several tissues and helps to regulate a whole-body state of metabolism. Under these conditions, the hydrolysis of triacylglycerol (TG) that is found in white adipocytes is known to be augmented via the activation of these lipolytic events, which is referred to as the “lipolytic cascade.” Indeed, evidence has shown that the lipolytic responses in white adipocytes are upregulated by continuous exercise training (ET) through the adaptive changes in molecules that constitute the lipolytic cascade. During the past few decades, many lipolysis-related molecules have been identified. Of note, the discovery of a new lipase, known as adipose triglyceride lipase, has redefined the existing concepts of the hormone-sensitive lipase-dependent hydrolysis of TG in white adipocytes. This review outlines the alterations in the lipolytic molecules of white adipocytes that result from ET, which includes the molecular regulation of TG lipases through the lipolytic cascade

Selective loss of GABAB receptors in orexin/hypocretin-producing neurons results in disrupted sleep/wakefulness architecture

We generated mice with a selective loss of GABAB receptors in orexin neurons. Orexin neurons in these GABAB1<sup>-/-(orexin)</sup> mice showed reduced responsiveness to GABA<sub>A</sub> receptor agonists due to a compensatory increase in GABAA receptor-mediated inhibition. This increased GABA<sub>A</sub> receptor-mediated inhibition of orexin neurons is due to orexin-1 receptor-mediated activation of local GABAergic interneurons. Surprisingly, orexin neurons were also less responsive to glutamate, apparently because the augmented GABA<sub>A</sub> receptor-mediated inhibition increases the membrane conductance and shunts excitatory currents. These observations indicate that absence of GABA<sub>B</sub> receptors decreases the sensitivity of orexin neurons to both excitatory and inhibitory inputs. GABAB1<sup>-/-(orexin)</sup>mice exhibited severe fragmentation of sleep/wake states during both the light and dark periods without affecting total sleep time or inducing cataplexy, indicating that GABA<sub>B</sub> receptors are crucial regulators of orexin neurons and that "fine tuning" of orexin neurons by inhibitory and excitatory inputs is important for the stability of sleep/waking states