Emergent Implications of the ‘Combined School’ Phenomenon: Lessons from the Upgraded Nangula Combined School in Limulunga District, Zambia

This study was conducted at Nangula Combined school in Limulunga District of Western Province, Zambia. It investigated the emergent implications of the ‘Combined School’ phenomenon through experiences of selected stakeholders of the said school using qualitative methodology and Case Study design. The study sample had 25 participants who were purposively sampled. Key findings of the study revealed that the school had experienced some slight positive changes in infrastructural development. The study also revealed that the introduction of senior secondary classes in the school had been appreciated by all stakeholders as it had reduced some distances that learners cover to access education. On a negative part, the study found that the school had a critical shortage of staff accommodation. The few available houses were in a dilapidated state. Inadequate desks, tables and chairs and weekly boarding facilities also characterized the experiences in this school. Further findings of this study were that the school was understaffed, especially at the primary section, which had three teachers only. Besides, the existence of both primary school trained teachers and secondary school trained teachers in one school enhanced the superiority and inferiority complexes. The school had an inadequate supply of teaching and learning resources coupled with the absence of specialized rooms, technology facilities like mobile network and internet connectivity. Thus, it is recommended that the government should embark on infrastructural development and provide adequately trained teachers. Provision of teaching and learning resources and more desks, chairs and tables should be a priority. It is important also to facilitate the upgrading of teachers who have acquired higher professional qualifications. To curb the inferiority and superiority perceptions that exists between the secondary trained teachers and the primary trained teachers, the study recommends that the two sections be split and work independently.

Kasteleyn Theorem, Geometric Signatures and KP-II Divisors on Planar Bipartite Networks in the Disk

Maximal minors of Kasteleyn sign matrices on planar bipartite graphs in the disk count dimer configurations with prescribed boundary conditions, and the weighted version of such matrices provides a natural parametrization of the totally non–negative part of real Grassmannians (Postnikov et al. J. Algebr. Combin. 30(2), 173–191, 2009; Lam J. Lond. Math. Soc. (2) 92(3), 633–656, 2015; Lam 2016; Speyer 2016; Affolter et al. 2019). In this paper we provide a geometric interpretation of such variant of Kasteleyn theorem: a signature is Kasteleyn if and only if it is geometric in the sense of Abenda and Grinevich (2019). We apply this geometric characterization to explicitly solve the associated system of relations and provide a new proof that the parametrization of positroid cells induced by Kasteleyn weighted matrices coincides with that of Postnikov boundary measurement map. Finally we use Kasteleyn system of relations to associate algebraic geometric data to KP multi-soliton solutions. Indeed the KP wave function solves such system of relations at the nodes of the spectral curve if the dual graph of the latter represents the soliton data. Therefore the construction of the divisor is automatically invariant, and finally it coincides with that in Abenda and Grinevich (Sel. Math. New Ser. 25(3), 43, 2019; Abenda and Grinevich 2020) for the present class of graphs.

Using Stelfrine supra 2.5% for children with accommodation and refraction disabilities

AIM:To assess the effect of Stelfrin supra (phenylephrine 2.5%) on the condition of accommodation, refraction and evaluate subjective comfort in instillation and adolescents with various refractive disorders. MATERIALS AND METHODS:Examined 45 people with mild emmetropia and hyperopia with symptoms of habitual excess tension of accommodation (15 people), with mild myopia (15 people), with moderate myopia (15 people) at the age of 7 to 16 years. Visometry, autorefractometry, assessment of the volume of absolute accommodation (positive and negative parts), subjective assessment of asthenopic complaints according to the OSDI scale were carried out before and 1 month after daily instillations of Stelfrin supra (phenylephrine 2.5%). RESULTS:After 1 month of instillation of the Stelfrin supra, the manifestations of accommodative asthenopia in the vast majority of patients in the study groups decreased, the habitual tonus of accommodation decreased, the volume of absolute accommodation increased, most significantly its negative part. The uncorrected visual acuity increased by 31% in patients of group 1 with emmetropia and mild hyperopia with habitually excessive tension of accommodation. The uncorrected visual acuity increased by 23% in patients of group 2 with mild myopia. An increase in the margin of relative accommodation was noted in patients of groups 1 and 2. Instillation of the drug was not accompanied by severe discomfort in the vast majority of patients. CONCLUSIONS:Stelfrin supra has shown its effectiveness in accommodating and refractive disorders in childhood and can be recommended in the treatment of children with accommodation disorders, asthenopia and mild to moderate myopia.

A Two-Phase Algorithm for Robust Symmetric Non-Negative Matrix Factorization

As a special class of non-negative matrix factorization, symmetric non-negative matrix factorization (SymNMF) has been widely used in the machine learning field to mine the hidden non-linear structure of data. Due to the non-negative constraint and non-convexity of SymNMF, the efficiency of existing methods is generally unsatisfactory. To tackle this issue, we propose a two-phase algorithm to solve the SymNMF problem efficiently. In the first phase, we drop the non-negative constraint of SymNMF and propose a new model with penalty terms, in order to control the negative component of the factor. Unlike previous methods, the factor sequence in this phase is not required to be non-negative, allowing fast unconstrained optimization algorithms, such as the conjugate gradient method, to be used. In the second phase, we revisit the SymNMF problem, taking the non-negative part of the solution in the first phase as the initial point. To achieve faster convergence, we propose an interpolation projected gradient (IPG) method for SymNMF, which is much more efficient than the classical projected gradient method. Our two-phase algorithm is easy to implement, with convergence guaranteed for both phases. Numerical experiments show that our algorithm performs better than others on synthetic data and unsupervised clustering tasks.

Determination of Activation Energy of Surface Diffusion Based on Thermal Oscillations of Atoms

This paper covers calculations of the activation energy of surface diffusion of ad-atoms on the substrate surface from the point of view of thermal oscillations of substrate atoms and ad-atoms. The main characteristic of oscillations of atoms and geometric mean frequency was calculated based on statistical approximation of the Debye model using the reference values of entropy and heat capacity of metals. The basic principle of the model of activation energy calculation presented in the paper is the formation of potential wells and barriers during oscillations of atoms localized in the sites of the lattice. Oscillations of atoms were considered in the framework of quasiclassical quantum approximation as the oscillations of harmonic oscillators in the potential parabolic wells. Dimensions of the negative part of values of the potential well energy were determined by the amplitude of thermal oscillations of atoms. Positive values constituted a significant part of the potential well energy values. Barriers were formed owing to interaction of positive values of the energy of parabolic wells of adjacent atoms. Therefore, in order to make the ad-atom jump, it is necessary to get out of the potential well having the negative values, and to overcome the potential barrier. The energy required for the ad-atom jump on the substrate surface was the activation energy of surface diffusion. The results obtained in this paper agree satisfactorily with the results of another method, which is based on determining the energy of ad-atom binding with the substrate atoms.

Enhanced Flip-FBMC visible light communication model

<p>VLC technology is one of the most promising technologies in the generations of communications, especially 5G after the significant development of optical semiconductors, specific laser diode, and the use of FBMC modulation in the system. DCO-FBMC modulation surpasses all the disadvantages of DCO-OFDM modulation techniques, as it is characterized by high speed and large bandwidth, but this technique consumes high energy when converting a real bipolar signal into a positive unipolar by adding DC-bias. Besides the challenge of illumination distribution indoor typical room, where the drop of the illumination appears in the middle of the room, besides the power consumption. The Flip-FBMC technique was proposed to solve this challenge, which helps convert the bipolar signal into unipolar by separating the positive part from the negative part and converting it into positive and merging it using Multiplexer and then sending the signal. Besides this, the authors presented in this paper a new lighting model with 5 luminescent units, using LD instead of LED. The Flip-FBMC profile gave better energy savings and BER performance than DCO-FBMC, besides a lighting model that covers dark areas and gives high SNR for the blind area and give save power 13.14% from consumed power.</p>

Study of the Ecological Footprint and Carbon Footprint in a Reverse Osmosis Sea Water Desalination Plant

The water situation in the Canary Islands has been a historical problem that has been sought to be solved in various ways. After years of work, efforts have focused on desalination of seawater to provide safe water mainly to citizens, agriculture, and tourism. Due to the high demand in the Islands, the Canary Islands was a pioneering place in the world in desalination issues, allowing the improvement of the techniques and materials used. There are a wide variety of technologies for desalination water, but nowadays the most used is reverse osmosis. Desalination has a negative part, the energy costs of producing desalinated water are high. To this we add the peculiarities of the electricity generation system in the Canary Islands, which generates more emissions per unit of energy produced compared to the peninsular generation system. In this study we have selected a desalination plant located on the island of Tenerife, specifically in the municipality of Granadilla de Abona, and once its technical characteristics have been known, the ecological footprint has been calculated. To do this we have had to perform some calculations such as the capacity to fix carbon dioxide per hectare in the Canary Islands, as well as the total calculation of the emissions produced in the generation of energy to feed the desalination plant.

Mixed type integro-differential equation with fractional order Caputo operators and spectral parameters

The issues of unique solvability of a boundary value problem for a mixed type integro-differential equation with two Caputo time-fractional operators and spectral parameters are considered. A mixed type integro-differential equation is a partial integro-differential equation of fractional order in both positive and negative parts of multidimensional rectangular domain under consideration. The fractional Caputo operator's order is less in the positive part of the domain, than the order of Caputo operator in the negative part of the domain. Using the method of Fourier series, two systems of countable systems of ordinary fractional integro-differential equations with degenerate kernels are obtained. Further, a method of degenerate kernels is used. To determine arbitrary integration constants, a system of algebraic equations is obtained. From this system, regular and irregular values of spectral parameters are calculated. The solution of the problem under consideration is obtained in the form of Fourier series. The unique solvability of the problem for regular values of spectral parameters is proved. To prove the convergence of Fourier series, the properties of the Mittag-Leffler function, Cauchy-Schwarz inequality and Bessel inequality are used. The continuous dependence of the problem solution on a small parameter for regular values of spectral parameters is also studied. The results are formulated as a theorem.