A fast solver for linear systems with displacement structure

We describe a fast solver for linear systems with reconstructable Cauchy-like structure, which requires O(rn^2) floating point operations and O(rn) memory locations, where n is the size of the matrix and r its displacement rank. The solver is based on the application of the generalized Schur algorithm to a suitable augmented matrix, under some assumptions on the knots of the Cauchy-like matrix. It includes various pivoting strategies, already discussed in the literature, and a new algorithm, which only requires reconstructability. We have developed a software package, written in Matlab and C-MEX, which provides a robust implementation of the above method. Our package also includes solvers for Toeplitz(+Hankel)-like and Vandermonde-like linear systems, as these structures can be reduced to Cauchy-like by fast and stable transforms. Numerical experiments demonstrate the effectiveness of the software.Comment: 27 pages, 6 figure

Synthesis, functionalization and applications of 2,5-bis(hydroxymethyl)furan (BHMF): a stable bio-based diol

In the last twenty years biorefinery has gained exceptional attention in the scientific community. This interest has been prompted by the substitution of petroleum-based compounds with renewable substances with the aim of establishing a bio-based economically self-sustained industry. In this view, C6 furan-based compounds, usually referred as furanics, have been extensively investigated as aromatic promising building blocks from renewables. 5-Hydroxymethylfurfural (HMF) and 2,5-furan dicarboxylic acid (FDCA) are well known examples of furanics whose syntheses and applications have been extensively reviewed in the literature.[1] This presentation is focused on our latest results on the synthesis, functionalization and application of yet another interesting furanic bio-based platform chemicals, i.e., 2,5-bis(hydroxymethyl)furan (BHMF).[2] BHMF is a stable bio-based diol with numerous applications as monomer for bio-materials and fuels. In our most recent works we have reported that BHMF can be prepared in large scale via a two-steps reaction. First HMF was prepared from D-fructose via acid catalyzed reaction employing dimethyl carbonate:tetraethyl ammonium bromide as biphasic solvent system. Thus, HMF - recovered from the reaction mixture with minimal work-up was converted to BHMF by reduction.[3] BHMF was consequently alkylated to achieve a library of 2,5-bis(alkoxymethyl) furans (BAMFs) with potential applications as biofuel candidates.[4] Furthermore, reaction of BHMF with several dialkyl carbonates allowed the preparation of BHMF alkyl carbonates in mild conditions.[5] These new compounds resulted stable over time and they are suitable monomers for new bio-based polycarbonates and polyurethanes

A Quantitative Study of Perceived Fitness and Nutrition Levels of Secondary Educators in Relation to Their Overall Job Satisfaction Program at a Private Midwestern University

The profession of education traditionally embodies an idea of educating children on math, science, social studies, and English along with other elective course areas. In recent decades, however, the burnout rates and mental health of educators have become a subject of media attention and the basis for many new professional development programs. The one element wholly ignored in this space is the physiological wellbeing of educators and the impact physical health has on mental health and job satisfaction. This study set out to provide a baseline for beginning the discussion and future research on the physiological impact on educators and how to improve the lives of educators, how they interact with students, and how to improve the physiological preparation of future educators. While this study did not conclusively identify the connection between nutrition and fitness and educators’ overall job satisfaction, it did highlight the gap between the public service occupation of education and that of other public servants, as well as highlighting the emerging connections between nutrition and mental health

Towards Scalable Synthesis of Furanics: Products Purification and Comparative Environmental Assessment

5-Hydroxymethylfurfural (HMF) is an archetype of bio-based platform chemicals, molecules derived by biomass that are the focus of Biorefinery research field.[1] HMF can be easily prepared from D-fructose via acid-catalyzed triple dehydration. This synthesis was carried out in the presence of numerous catalysts such as mineral and Lewis acids, metal chlorides, metal oxides, heteropolyacids and ion-exchange resins to mention just a few. [2] Although all these catalysts lead to an efficient conversion of D-fructose into HMF, typical reaction drawbacks include harsh reaction conditions and difficult isolation of the target molecule from the reaction media. Furthermore, despite the large number of publications reported in the literature, only limited attention has been focused on the separation of HMF from the reaction mixture. As a result, most of syntheses leading to HMF and furanics are based on small scale reactions where separation and isolation strategies are rarely addressed. Our interest into furanics is related to their upgrading into a variety of valueadded derivatives, such as chemicals, materials, bio-based polymers and fuels. In this prospect it is pivotal to develop simple synthetic approaches addressing both isolation and purification of these compounds. In recent years we have investigated gram to multi-grams scale syntheses of HMF,[3] 5-bis(hydroxymethyl)furan (BHMF), 2,5-bis[(alkoxycarbonyl) oxymethyl]furan (BAMF),[4] 2,5 Bis[(alkoxycarbonyl)oxymethyl] furan (BCMF)[5], 2,5-furandicarboxylic acid dimethyl ester (FDME)[6] and more recently 5,5 '(oxy-bis(methylene)bis-2-furfural (OBMF) and its derivatives. Most of the abovementioned compounds have been achieved employing commercially available catalysts, green solvents, mild reaction conditions and the products were isolated as pure via simple purification procedures. Furthermore, for specific examples green metrics and materials efficiency performance of the reported procedures have also been investigated taking into account E-factor and PMI green metrics

BUILDING A LIBRARY OF FURANICS IN GRAM SCALE

5-Hydroxymethylfurfural (HMF) - considered an archetype of bio-based platform chemicals[1] - can be easily prepared from D-fructose via triple dehydration catalysed by different types of acid catalysts including mineral and Lewis acids, metal chlorides, metal oxides, heteropolyacids and ion-exchange resins, etc.[2] Main drawbacks of this synthetic approach include harsh reaction conditions and difficult isolation of the target molecule from the reaction media. Furthermore, most of the syntheses leading to HMF - and in general furanics - are conducted on small scale reactions where separation and isolation strategies are rarely addressed. In our research group we are interested in investigating the synthesis and the subsequent upgrade of HMF - and other bio-based platform chemicals - into a variety of value-added derivatives, such as chemicals, fine chemicals, materials, bio-based polymers and fuels. In this prospect it is essential to develop simple gram scale synthetic approaches addressing both isolation and purification of these compounds. In recent years we have investigated gram scale syntheses of HMF,[3] 5-bis(hydroxymethyl)furan (BHMF), 2,5-bis[(alkoxycarbonyl)oxymethyl]furan (BAMF),[4] 2,5-Bis[(alkoxycarbonyl)oxymethyl] furan (BCMF)[5], 2,5-furandicarboxylic acid dimethyl ester (FDME)[6] and 5,5 '(oxy-bis(methylene)bis-2-furfural (OBMF) and its derivatives.[7] Most of the abovementioned compounds have been achieved employing commercially available catalysts, green solvents, mild reaction conditions and the products were isolated as pure via simple purification procedures. Besides in some cases the related green metrics have also been investigated

Testing the methods to reconstruct and model the Baryonic Acoustic Oscillations of different tracers using N-body simulations

The accelerated expansion of the Universe and the nature of the Dark Energy are still open questions in cosmology. One of the most powerful ways to investigate these issues is to map the large-scale structure of the Universe, to constrain its expansion history and growth of structures. In particular, baryon acoustic oscillations (BAO) occurred at recombination make a peak in the correlation function of galaxies at the characteristic scale of the sound horizon (a sufficiently large scale to “protect” the signal from strong non-linearities), or alternatively a series of oscillations in the power spectrum. Since the sound horizon can be estimated with a great precision from the position of the first peak in the angular power spectrum of the Cosmic Microwave Background (which has the same physical origin of BAO, oscillations of the baryons-photons plasma), the BAO peak in the correlation function can be used as a standard ruler, providing paramount cosmological information. The aim of this thesis is to systematically test and possibly improve the state-of- the-art statistical methods to model the BAO peak, taking into account the non-linear evolution of matter overdensities, redshift-space distortions and the bias of cosmic tracers. To do that, we analyse mock samples of galaxies, quasars and galaxy clusters extracted from one of the largest available cosmological hydrodynamical simulations. We extract cosmological constraints from the BAO peak through different statistical tools in the redshift range 0.2 < z < 2. Although the BAO peak is at large scales, non-linear growth and galaxy peculiar velocities make the BAO signal smoothed and broader with respect to linear predictions, especially at low redshifts. A possible method to overcome these issues is the so-called reconstruction of the density field: one of the primary goals of this work is to implement a reconstruction method, to check its performances as a function of sample selections and redshift

The Legend of Question Six

The final question 1988 International Math Olympiad in Melbourne Australia, presented to the world’s best and brightest young minds, would evolve to become one of most difficult questions in Mathematics. Of the 260 participants, only eleven were able to solve Question Six perfectly in the given amount of time, proving too difficult even for future Field’s Medalist Terence Tao. Question Six simply states “Let a and b be positive integers such that ab + 1 divides a2 + b2. Show that the resulting integer is a perfect square”. This research explores a definitive solution to the infamous question, and features questions utilizing a similar train of thought, featuring an emergent proof technique that is new to the world of Mathematics

- PENGARUH PEMBERIAN EKSTRAK AMPAS KOPI TERHADAP LAJU PERTUMBUHAN RAMBUT

Kopi memiliki banyak manfaaat yang baik bagi kesehatan maupun kecantikan. Hal ini disebabkan dalam penelitian kandungan kafein yang terdapat pada kopi sangat baik untuk rambut. Tujuan penelitian ini adalah untuk mengetahui pemberian ekstrak ampas kopi terhadap laju pertumbuhan rambut. Penelitian ini telah dilakukan selama 3 (tiga) bulan pada April sampai Juni 2018. Penelitian meliputi pemeliharaan hewan uji dan pembuatan ekstrak yang akan di Laboratorium Dasar Universita Samudra dan pembuatan produk bio hair tonic akan dilaksanakan di Universitas Sumatera Utara. Pengujian aktivitas ampas kopi terhadap pertumbuhan rambut kelinci jantan Punggung kelinci dibersihkan dari rambut dengan cara dicukur hingga bersih, dibagi menjadi 5 bagian yang masing-masing berbentuk segi empat 2 x 2,5 cm dan jarak antar daerah 1 cm. Pertumbuhan rambut pada kontrol Negatif mengalami pertumbuhan rambut yang lebih lambat dibandingkan perlakuan 3,4,5 dan kontrol positif akan tetapi setiap minggunya tetap mengalami pertumbuhan panjang rambut. Perlakuan 3 (2,37 cm) terlihat pada hari ke-28 mempunyai panjang rambut yang lebih panjang dibandingkan dengan kontrol positif (2,12 cm), perlakuan 4 (2,08 cm) dan perlakuan 5 (1,89 cm). &nbsp

Technology-enhanced Pathways to Active Learning: Student Response Systems Facilitating Peer-instruction and Self-assessment in Large Classrooms

This paper describes an active learning approach implemented in a first-year undergraduate course in Introductory Macroeconomics taught at the University of East Anglia. The first part of the paper explains the motivation that led me to introduce this approach, which builds on powerful pedagogies such as self-assessment and peer-instruction, as well as on technology-enhanced learning through Student Response Systems. In the second part of the paper, I report on the mixed-methods evaluation strategy implemented to appraise pedagogical effectiveness. Whilst only briefly commenting on quantitative indicators, which have been the focus of previous publications, the focus of this paper is on qualitative data that conveys students’ perceptions of their learning experiences when using the approach. Analysis of the qualitative data highlights that students view my pedagogical approach, as well as its technology-enhanced implementation, as supportive of student learning, and as a means of enhancing their self-efficacy beliefs. The pedagogic approach is especially welcomed by students coming from an international background, characterised by diverse previous learning experiences. The approach also appears to be particularly effective for students who are struggling with their learning