Optimal post-stratification for the study of the sustainability: An application to the monitoring of diversity in Sierra de Guerrero

The need of designing a monitoring network in Sierra de Guerrero motivated this paper. The study of the effect of deforestation of the forest needs of monitoring in the diversity. A quantitative evaluation of diversity is measured by estimating an index. Commonly the monitoring of biodiversity is based on the periodical selection of samples for evaluating the diversity. We propose to use sample information for determining post strata. They must constitute homogeneous zones in the forest. A stochastic program is developed for determining the post strata to be used for sampling. The procedure seems to be a good alternative with respect to the use of a heuristic procedure. The results presented are based on the data obtained in a research developed at one of the most important forest diversity reservoirs of Mexico     

The effects of channel diameter on flow pattern,void fraction and pressure drop of two-phase air–water flow in circular micro-channels

Two-phase air–water flow characteristics are experimentally investigated in horizontal circular micro-channels. Test sections are made of fused silica. The experiments are conducted based on three different inner diameters of 0.53, 0.22 and 0.15 mm with the corresponding lengths of 320, 120 and 104 mm, respectively. The test runs are done at superficial velocities of gas and liquid ranging between 0.37–42.36 and 0.005–3.04 m/s, respectively. The flow visualisation is facilitated by systems mainly including stereozoom microscope and high-speed camera. The flow regime maps developed from the observed flow patterns are presented. The void fractions are determined based on image analysis. New correlation for two-phase frictional multiplier is also proposed for practical applications.     

Mutation of Torsion Pairs in Cluster Categories of Dynkin Type D

In cluster categories, mutation of torsion pairs provides a generalisation for the mutation of cluster tilting subcategories, which models the combinatorial structure of cluster algebras. In this paper we present a geometric model for mutation of torsion pairs in the cluster category \(\mathcal {C}_{D_{n}}\) of Dynkin type D _n . Using a combinatorial model introduced by Fomin and Zelevinsky in [7], subcategories in \(\mathcal {C}_{D_{n}}\) correspond to rotationally invariant collections of arcs in a regular 2n-gon, called diagrams of Dynkin type D _n . Torsion pairs in \(\mathcal {C}_{D_{n}}\) have been classified by Holm, Jørgensen and Rubey in [10] and correspond to diagrams of Dynkin type D _n satisfying a certain combinatorial condition, called Ptolemy diagrams of Dynkin type D _n . We define mutation of a diagram \(\mathcal {X}\) of Dynkin type D _n with respect to a compatible diagram \(\mathcal {D}\) of Dynkin type D _n consisting of pairwise non-crossing arcs. Such a diagram \(\mathcal {D}\) partitions the regular 2n-gon into cells and mutation of \(\mathcal {X}\) with respect to \(\mathcal {D}\) can be thought of as a rotation of each of these cells. We show that mutation of Ptolemy diagrams of Dynkin type D _n corresponds to mutation of the corresponding torsion pairs in the cluster category of Dynkin type D _n .     

Nickel(II) tellurolates: preparative,spectral and electrochemical studies

Summary Complexes of the type [NiCl(TeAr)(DPPE)] (1) and [Ni-(TeAr)₂(DPPE)] (2) [Ar = Ph, C₆H₄Me-4, C₆H₄OMe-4 or C₆H₄OEt-4; DPPE = 1, 2-bis(diphenylphosphino)-ethane] were prepared from [NiCl₂(DPPE)] and NaTeAr (generated in situ) in EtOH-C₆H₆. Their structures were established by elemental analysis, conductance and molecular weight measurements and i.r., electronic, ¹H and ³¹ Pn.m.r. spectra. The analytical and spectroscopic data are consistent with a square planar geometry around nickel in (1) and (2). Metathetical reactions between (1) (Ar = C₆H₄OMe-4) and NaX (X = I or Br) in MeOH give [NiX(TeAr)(DPPE)] (3). Electrochemical studies of (1) and (2) using c.v. indicate an irreversible cathodic peak (ca. –0.76 to 0.86 V) corresponding to reduction of nickel(II) to nickel(0) and an irreversible anodic peak (ca. –0.04 to 0.37 V) for oxidation of the tellurolate ligand.     

Immunogenicity of Foot-and-Mouth Disease Virus Dendrimer Peptides: Need for a T-Cell Epitope and Ability to Elicit Heterotypic Responses

An approach based on a dendrimer display of B- and T-cell epitopes relevant for antibody induction has been shown to be effective as a foot-and-mouth disease (FMD) vaccine. B₂T dendrimers combining two copies of the major FMD virus (FMDV) type O B-cell epitope (capsid proteinVP1 (140–158)) covalently linked to a heterotypic T-cell epitope from non-structural protein 3A (21–35), henceforth B₂T-3A, has previously been shown to elicit high neutralizing antibody (nAb) titers and IFN-γ-producing cells in both mice and pigs. Here, we provide evidence that the B- and T-cell epitopes need to be tethered to a single molecular platform for successful T-cell help, leading to efficient nAb induction in mice. In addition, mice immunized with a non-covalent mixture of B₂T-3A dendrimers containing the B-cell epitopes of FMDV types O and C induced similarly high nAb levels against both serotypes, opening the way for a multivalent vaccine platform against a variety of serologically different FMDVs. These findings are relevant for the design of vaccine strategies based on B- and T-cell epitope combinations.     

An experimental investigation of two-phase air–water flow through a horizontal circular micro-channel

This paper is a continuation of the authors’ previous work. Two-phase air–water flow experiments are performed in a horizontal circular micro-channel. The test section is made of a fused silica tube with an inner diameter of 0.15 mm and a length of 104 mm. The flow phenomena, which are liquid/unstable annular alternating flow (LUAAF), liquid/annular alternating flow (LAAF), and annular flow, are observed and recorded by a high-speed camera mounted together with a stereozoom microscope. A flow pattern map is presented in terms of the phase superficial velocities and is compared with those of other researchers obtained from different working fluids. Image analysis is performed to determine the void fraction, which increases non-linearly with increasing volumetric quality. It is revealed that the two-phase frictional multiplier data show a dependence on flow pattern rather than mass flux. Based on the present data, a new pressure drop correlation is proposed for practical applications. According to the present study, in general the data for the two-phase air–water flow characteristics are found to comply with those of working fluids other than air–water mixtures.     

Bulk optode sensors for batch and flow-through determinations of lead ion in water samples

A sensitive optode consisting of highly lead-selective ionophore (Lead IV), proton-selective chromoionophore (ETH 5294) and lipophilic anionic sites (KTpClPB) in plasticized polyvinyl chloride (PVC) membrane was fabricated. The optode membranes were used for determination of Pb²⁺ by absorption spectrophotometry in batch and flow-through systems. The influence parameters such as pH, type of buffer solution, response time and concentration of regenerating solution were optimized. The membrane responded to Pb²⁺ by changing its color from blue to pinkish purple in Tris buffer containing different concentration of Pb²⁺ at pH 7.0. The optode provided the response range of 3.16 × 10⁻⁸ to 5.00 × 10⁻⁵ mol L⁻¹ Pb²⁺ with the detection limit of 2.49 × 10⁻⁸ mol L⁻¹ in the batch system within the response time of 30 min. The dynamic range of 1.26 × 10⁻⁸ to 3.16 × 10⁻⁵ mol L⁻¹ Pb²⁺ with detection limit of 8.97 × 10⁻⁹ mol L⁻¹ were obtained in the flow-through system within the response time of 15 min. Moreover, the proposed optode sensors showed good selectivity towards Pb²⁺ over Na⁺, K⁺, Mg²⁺, Cd²⁺, Hg²⁺ and Ag⁺. It was successfully applied to determine Pb²⁺ in real water samples and the results were compared with well-established inductively coupled plasma optical emission spectrometry (ICP-OES). No significant different value (t_critical = 4.30 > t_exp = 1.00-3.42, n = 3 at 95% of confidence level) was found.     

Two-phase flow of R-134a refrigerant during flow boiling through a horizontal circular mini-channel

This research focuses on heat transfer to R-134a during flow boiling in a 1.75 mm internal diameter tube. Flow visualisation and heat transfer experiments are conducted to obtain heat transfer coefficients for different flow patterns. The measured data in each flow regime are compared with predictions from a three-zone flow boiling model. The calculations are in fair agreement with the experimental results which correspond in particular to slug flow, throat-annular flow and churn flow regimes under conditions of low heat flux.     

Graded quantum cluster algebras of infinite rank as colimits

We provide a graded and quantum version of the category of rooted cluster algebras introduced by Assem, Dupont and Schiffler and show that every graded quantum cluster algebra of infinite rank can be written as a colimit of graded quantum cluster algebras of finite rank.As an application, for each k we construct a graded quantum infinite Grassmannian admitting a cluster algebra structure, extending an earlier construction of the authors for $k=2$.