Spinon-Holon binding in t−Jt-J model

Using a phenomenological model, we discuss the consequences of spinon-holon binding in the U(1) slave-boson approach to $t-J$ model. Within a small $x$ ($x=$ hole concentration) expansion, we show that spinon-holon binding produces a pseudo-gap normal state with a segmented Fermi surface and the superconducting state is formed by opening an "additional" d-wave gap on the segmented Fermi surface. The d-wave gap merge with the pseudo-gap smoothly as temperature $T\to0$. The quasi-particles in the superconducting state are coupled to external electromagnetic field with a coupling constant of order $x^{\gamma}$ where $0\leq\gamma\leq1/2$, depending on the strength of the effective spinon-holon binding potential.Comment: 9 pages, 3 figure

The complement of the Bowditch space in the SL(2,C) character variety

Let ${\mathcal X}$ be the space of type-preserving \SL(2,C) characters of the punctured torus $T$. The Bowditch space ${\mathcal X}_{BQ}$ is the largest open subset of ${\mathcal X}$ on which the mapping class group acts properly discontinuously, this is characterized by two simple conditions called the $BQ$-conditions. In this note, we show that $[\rho]$ is in the interior of the complement of ${\mathcal X}_{BQ}$ if there exists an essential simple closed curve $X$ on $T$ such that $|{\rm tr} \rho(X)|<0.5$.Comment: 6 page

Compactifications of F-Theory on Calabi-Yau Threefolds at Constant Coupli ng

Generalizing the work of Sen, we analyze special points in the moduli space of the compactification of the F-theory on elliptically fibered Calabi-Yau threefolds where the coupling remains constant. These contain points where they can be realized as orbifolds of six torus $T^6$ by $Z_m \times Z_n (m, n=2, 3, 4, 6)$. At various types of intersection points of singularities, we find that the enhancement of gauge symmetries arises from the intersection of two kinds of singularities. We also argue that when we take the Hirzebruch surface as a base for the Calabi- Yau threefold, the condition for constant coupling corresponds to the case where the point like instantons coalesce, giving rise to enhanced gauge group of $Sp(k)$.Comment: 13 pages, Latex, no figures, 1 table, some error in the original version correcte

Modelling the squeeze flow in a deformed rectangular microchannel

Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech.Rheinforce cork composites, previously named elsewhere as CorkSTFluidics [1], are sandwiches consis?ng of two microagglomerated cork pads embedding microfluidic paCerns that are filled with a shear thickening fluid (see Figure 1 (a)), whose mechanical performance under impact loads is determined by the microfluidic paCern and the rheological proper?es of the fluid [2]. From the experimental results it is impossible to decouple the fluid contribu?on from the solid contribu?on to the force?me response of the composite. In this work, we have developed a simple model of the fluid-flow dynamics that it is able to predict the fluid contribu?on in the energy dissipa?on of the Rheinforce cork composites under impact loads. To that end, we model the viscous flow inside a microchannel for a known displacement of the upper lid h(t, x), calcula?ng as a result the needed force to create that movement

Permeable Reactive Barriers using nanoparticles to remediate nitrate pollution

Nitrat e (NO3 - ) i s per vasi ve i n t he bi ospher e[ 1, 2]. Cont emporar y agri cult ural pr acti ces are a mong t he maj or ant hr opogeni c sources of r eacti ve nitrogen speci es, wher e nitrat ei s t he most abundant of t hese [ 2]. Excessi ve a mount s of r eacti ve nitrogen i n soil s and gr oundwat er ar e creati ng si gnifi cant t hr eat s t o hu man healt h and saf et y [ 3] as well as a host of undesirabl e environment al i mpact s [ 2]; it i s curr ently consi der ed t he second most r el evant environment al i ssue, aft er car bon di oxide e mi ssi ons. Nowadays, a mong t he most r el evant and pr omi si ng appr oaches t o r educe nitrat e concentrati on i n wat er, na mel y gr oundwat er, ar e denitrifi cati on- based pr ocesses [ 4]. Per meabl e r eacti ve barri ers ( PRB) have been pr oven eff ecti ve i n r educi ng vari ous cont ami nant s i n copi ous a mount s, parti cul arl y i n shall ow gr oundwat er [ 5]. However t he possi bl e added eff ecti veness of usi ng nanoparti cl es i n t hese structur es t o obt ai n nitrogen gas from nitrat es requires f urt her i nvesti gati on

Cost-allocation principles for pipeline capacity and usage

This paper applies principles f rom game theory to the problem o f allocating the cost o f a shared facility, such as a pipeline. The theory o f cooperative games s t r ongl y suggest s t hat no method e x i s t s for allocating costs that wi l l achieve all major policy goals. We apply results from the theory o f cooperative games a n d principles o f cost allocation to assess some c o mmo n l y adopted rules for allocating costs and def i ni ng u n i t charges. Mos t notably, the postage-stamp toll is f o u n d to fail a mi ni mal set o f commonly applied principles.cost allocation; pipeline