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here, a list of some image sources we found for you.
if you know any other good ones, please share them with us in the arena “tagging” Miri Esther, our responsible for keeping this list up-to-date!
> the commons (on flickr): from the world’s public photography archives.
> retronaut’s time capsules: see the past like you wouldn’t believe.
> the new york public library: digitalized original images from books, magazines and newspapers, mostly created before 1923.
> medieval and renaissance material culture: occupations, clothing, animals, tools, utensils, games, pastimes, crime, punishment… from the middle ages + renaissance!
> google art project: artworks, high-res + walk-through museums feature!
> world wonders project: explore historic sites as if you were there.
> historic moments: stories behind significant moments in human history.
> pixabay.com: free high res images, free videos as well!
> morguefile.com: high res stock photos by creatives for creatives!
> foter.com: free for non commercial use. “buildings” section is great.
> everystockphoto.com: a serch engine for free images or wirth a specific licence.
> im creator: some free, some not, but worth it!
#arc1o1exhibition goes to ural industrial biennial of contemporary art!
curator yana novoslugina for welcoming our matchboxes in such a beautifully curated way.
another very special thank you to our crew member dina neri for organizing the collaboration with okno gallery.
Comments Off on #arc1o1exhibition goes to ural industrial biennial of contemporary art!
we publish some as well!
in collages we really trust!
you like to write ?
Traditionally, quantum theory has been viewed as a "difficult" topic, mainly because of the symbolic-mathematical content. For example, Francl notes that two semesters of calculus is usually required for physical chemistry (1), and this is certainly true for quantum theory. The traditional approach emphases the use of mathematical equations, derivations and calculations. How do we deal with non-chemistry majors who have a weak background in mathematics, but wish to study p-chem? Similarly, how do we deal with chemistry majors who have a weak background in mathematics?
Interestingly, the last 20-30 years has witnessed a paradigm shift in the practice of quantum chemistry. Leading up to the 1970s, quantum chemistry was monopolized by theoretical chemists, who were as much mathematicians as chemists. One had to be conversant with the mathematical methodology in order to perform a quantum calculation. More recently, the amazing increases in computing power have lead to graphical user interfaces, which has enabled a new group ofcomputational chemists. These computational chemists are interested only in the significance of the computed results, not in the details of the mathematical methods used. However, the same paradigm shift in the teaching of quantum chemistry has not occurred yet: students are still required to be competent mathematicians.
The "new calculus" in mathematics education (eg, 2) advocates the "rule of four" (numerical, graphical, symbolic and verbal descriptions) to deepen students' conceptual understanding (eg, 3). This "new calculus" acknowledges that a predominantly symbolic approach to mathematics is suitable for some, but not all, students. The greater emphasis on graphical and verbal descriptions of a "problem" enables students to focus on the qualitative results. The numerical approach can refer either to approximate numerical solutions (cf modern computational chemistry software) or to specific numerical examples of more general symbolic equations.
This paper describes the use of spreadsheets to generate approximate numerical solutions and visual (graphical) descriptions as a method of avoiding or minimizing symbolic manipulations, mathematical derivations and numerical computation. The aim here is to teach the qualitative results that arise from quantum theory, but with less "math". The specific example of the one-dimensional Schrödinger equation and some aspects of the educational pedagogy of spreadsheet usage are discussed.
Electrons (and atoms?) exhibit both wave-like and particle-like behavior.
Students are usually first introduced to quantum theory through the wavefunctions for the 1-dimensional Schrödinger equation. Exact solutions are derived for the particle-in-a-box (the Kuhn model (4)) and the simple harmonic oscillator model. The shapes of the potentials for these models are shown in Figure 1.
Figure 1. Potential functions for the particle-in-a-box model (left) and the simple harmonic oscillator model (right).
where Hn(x) is the Hermite polynomial of order n. The novice learner sees the differences between Equation 1 and Equation 2 and concludes that every potential is treated as a special case!
Potentials such has the triangular and stepped-valley models, shown in Figure 2, have no closed-form (ie analytic) wavefunction solutions. Similarly, the quantized energies cannot be given by any analytic equation. Here, the novice learner concludes incorrectly either that quantum mechanics does not apply, or that many systems are not quantized!
Figure 2. Simple piecewise-continuous potential functions for which the wavefunction does not have any closed form: a triangular potential (left) and a stepped-valley potential (right).
In p-chem classes at Deakin University, the derivative is explained as the "slope of a function". The 2nd order differential Schrödinger equation for an electron-in-a-box (the Kuhn model (4)) is explained as "finding the slope of a slope". The 1st order Euler method for generating numerical solutions is explained. No calculus is required as the Euler method can be derived from the definition of average slope. More-able students can construct an appropriate spreadsheet (to find numerical solutions to the Schrödinger equation), but mostly, spreadsheet quantum_well.xls<http://www.deakin.edu.au/~lim/KFLim/papers/2003_Spreadsheet_CCEN/quantum_well.xls>, implementing the Schrödinger equation, is provided as a "black box" to weaker students. (The pros and cons of black box methods are discussed below.) Using the spreadsheet quantum_well.xls, students test how the shape of a trial "wavefunction" changes as the energy is varied (Figure 3). A copy of the instructions to students for this exercise can be found at<http://www.deakin.edu.au/~lim/KFLim/papers/2003_Spreadsheet_CCEN/Asgnt_1_6.pdf>. The wavefunction solutions are classed as "valid" or "invalid" depending on whether the boundary conditions are satisfied as energy is varied (the shooting method (6)).
Figure 3. Approximate trial wavefunctions for the triangular potential (Figure 2), arranged from high energy (top) to low energy (bottom). Shaded domains are the forbidden region: V(x) < E.
Students discover that energy determines the wavelength of the wavefunction, and that valid solutions require that only special ("allowed") wavelengths will fit the dimension of the potential (Figure 3). It is observed that, as wavelength decreases, the number of nodes (the zeroes or roots of the wavefunction) increases with energy. An extension of this exercise using a skipping rope easily verifies that it is more difficult (higher energy) to swing the rope with nodes present than without any nodes (lower energy). Since the sign of the wavefunction changes across a node, the qualitative shape of the wavefunction can be generated from the nodal pattern. (One strategy in de Bono's Lateral Thinking (7) is to concentrate on what is not present - ie the nodes or zeroes - in order to obtain what should be present - the wavefunction.) Wavefunctions can then be generated from nodal patterns in 2-dimensions and 3-dimensions.
For example, the molecular orbitals for cyclopentadienyl have, in increasing order of energy, no nodes, one node and two nodes respectively (Figure 4). Similarly, the rotational wavefunctions can be generated by considering nodal patterns on the surface of a sphere. Much of Schrödinger's original work was based on Hamilton's mathematical description of standing waves on a planet completely covered by ocean (ie water waves on a spherical surface). Note that these "spherical waves" correspond to combinations of the spherical harmonic functions, and can be obtained from the symmetry - "topology" - of the nodal patterns on the surface of a sphere.
Figure 4. molecular orbitals for cyclopentadienyl. Shading of the circles in the centre panels represent the sign (direction) of the pz orbitals. The pzorbitals change sign across nodal planes, which are shown as blue lines.
On further exploration with the spreadsheet quantum_well.xls, students discover that the shapes of the allowed one-dimensional wavefunctions are similar (Figure 5), even for different potential models: ie, the lowest-energy wavefunctions all have one "bump", with no nodes.
Figure 5. Lowest-energy approximate wavefunctions for the particle-in-a-box (top panel), simple harmonic oscillator (2nd panel), triangular (3rd panel) and stepped-valley (bottom panel) potentials of Figure 1 andFigure 2. Shaded domains are the forbidden region: V(x) < E.
the use of a series of square wells separated by barriers (extended Kronig-Penney model) illustrates that interactions between wells split energy levels. As the number of wells increases, the (single-well) energy splits into a quasi-continuous band of energies, giving rise to the band theory for conductors and semi-conductors.
Although there has been a substantial history in the use of spreadsheet and graphical applications in education (eg 9,10), the author believes that full utilization of the technology, especially in chemical education, has not been realized.
The aim of this paper is to teach the qualitative results that arise from applying mathematics to physical and chemical systems, but without the mathematical rigor: "teaching maths with minimal maths". The "new calculus" advocates the "rule of four" (numerical, graphical, symbolic and verbal descriptions) to deepen students' conceptual understanding (2). Students who have a weak background in mathematics do not have the knowledge of calculus required for the usual symbolic algebra approach to physical chemistry. This case study illustrates how a combination of numerical, graphical and verbal descriptions can be used to overcome the lack of symbolic knowledge or ability.
The Logical-Mathematical intelligence is only one of multiple "intelligences" (11). By changing the emphasis away from mathematical calculus, the numerical-experimental activity, can also cater to those students who favor Spatial or Bodily-Kinesthetic intelligences. A combination of this spreadsheet approach with the traditional calculus-based approach will enable more students (and students of more types of "intelligences") to study quantum theory.
This paper has focused on the use of spreadsheets but, in principle, the simulations can be done using symbolic mathematical packages such as Mathematica, Maple or MathCAD. This would only be feasible for students who already have a strong mathematical background. This author prefers the use of spreadsheets for weaker students for the following reasons. The symbolic mathematical packages depend on the use of a symbolic, quasi-programming language, which can present an additional learning obstacle for many students (12). Furthermore, the access to symbolic mathematical packages is usually more limited than that of spreadsheets, which are widely available in home, business and community settings. The "worldware" (13,14) (also called "application-software" (15)) nature of spreadsheets means that students will have greater opportunities to use and become familiar with spreadsheets than with (eg) symbolic mathematical packages, leading to greater utility and expertise: Software that isn't designed for instruction can still be good for learning (13). (A "straw poll" of physical chemistry faculty suggests that significantly more faculty use spreadsheets in teaching and learning activities than symbolic mathematical packages (16).
While weaker students will use the spreadsheets, discussed in this paper, as "black boxes", more able students can construct similar, appropriate spreadsheets (eg17-19). Instructors will need to be careful in deciding to use the "black box" approach or to require students construct their own. If successfully completed, the latter approach will promote deeper learning (19), but the greater complexity of the task (12) may mean that some students cannot complete the task, resulting in frustration and lack of learning.
The key feature of using spreadsheets is that students do "numerical experiments". (There is an interesting discussion of the use of numerical experiments in (20-22). Numerical experiments (eg 23) were also a key part of the development of chaos theory (20).) By playing with "what-if" scenarios, students can test the validity of their concepts and ideas: the success of using spreadsheets in this way is supported by cognitive constructivist models of learning (15,24,25). The use of spreadsheets is intended to give students a qualitative appreciation of quantum theory, and does not serve as a pre-requisite to more advanced studies in quantum theory, for which a reasonable knowledge of mathematics is required.
This paper is an expanded version of case studies to be published by LTSN Maths, Stats & OR Network <http://ltsn.mathstore.ac.uk/mathsteam> and by LTSN Physical Sciences <http://www.physsci.ltsn.ac.uk>.
KFL thanks Ms Jeanne Lee ( ) (Australian Catholic University) for encouraging and helpful discussions, Dr Paul Yates<http://www.keele.ac.uk/depts/ch/staff/pcy/pcy.html> (Keele University, UK) for suggestions to improve the spreadsheet quantum_well.xls, and Associate Professor (Emeritus) Ian Johnston <http://www.physics.usyd.edu.au/super/johnston.html> (Uniserve·Science, University of Sydney, Australia) <http://www.usyd.edu.au/su/SCH/> for a seminar on MUPPET (the Maryland University Project in Physics and Educational Technology) <http://www.physics.umd.edu/rgroups/ripe/computer.html> which introduced KFL to the possibilities of numerical experiments in teaching and learning.
All URLs checked on 7 March 2003.
Francl, M., Survival Guide for Physical Chemistry; Physics Curriculum and Instruction: Lakeville (MN), 2001.
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de Bono, E., Lateral Thinking: A textbook of creativity; Penguin: London, 1990.
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Kieran F. Lim ( ) obtained his BSc (Hons) and PhD in theoretical chemistry from the University of Sydney. He was awarded an Archbishop Mannix Travelling Scholarship to Stanford University and been a faculty member at the University of New England, the University of Melbourne and Deakin University, where he is currently a Senior Lecturer in Chemical Sciences (equivalent to Associate Professor or Professor in North America). He is a Member (MRACI), Chartered Chemist( CChem) and Certified Practising Chemist (CPChem) of the Royal Australian Chemical Institute, and a Member (MACS) and Practising Computer Professional (PCP) of the Australian Computer Society.
Dr Lim is a recipient of the Royal Australian Chemical Institute's Division of Chemical Education Citation for significant contributions to chemical education (2002) and the Faculty of Science and Technology's Excellence in Teaching Award (1996 and 2000).
New materials pictured below are coming soon! We still have current materials on hand, so let us know what you need.
Two-sided information card. 2" x 3.5"
Agora can provide you with posters, brochures and cards to give out to your friends, family, neighbors, clients, students...or anyone else you can think of!
The acclaimed British artist is having a moment.
David Hockney, Woldgate Woods, 24, 25 and 26 October, 2006(2006). The painting carries a $9 million–12 million estimate, which would set a new auction record for the artist. Courtesy of Sotheby’s New York.
Records could fall at Sotheby’s New York “Contemporary Art Evening Auction” on November 17, where the house is predicting a mammoth $9 million–12 million hammer price for Woldgate Woods, 24, 25 and 26, 2006, a massive 2006 landscape painting by David Hockney.
The acclaimed British artist is having a moment, riding off this summer’s international release of Randall Wright’s documentary Hockney, and looking ahead to the publication of his new book with art critic Martin Gayford, A History of Pictures: From the Cave to the Computer Screen, due out October 18.
Hockney, who will turn 80 next year, will also be the subject of a massive retrospective at Tate Britain, scheduled to run February 9–May 29, 2017. Billed as his most comprehensive exhibition to date, the show will include a number of never-before-seen works.
David Hockney, Beverly Hills Housewife(1966–67). Courtesy of Christie’s New York.
According to the artnet Price Database, Hockney’s current record at auction is $7.92 million, set in May 2009 at Christie’s New York with Beverly Hills Housewife. The 1966–67 diptych, from the “California Dreaming” series, is a portrait of the late art philanthropist and photographer Betty Freeman in front of her Los Angeles home.
The artist has had five other sales in excess of $5 million, all over the last 10 years.
This number appears to be somewhat of a sweet spot for Hockney, as none of those lots topped $5.5 million. The first sale at that price point came in 2006 at Sotheby’s London, for the iconic 1966 swimming pool painting, The Splash.
David Hockney, The Splash (1966). Courtesy of Sotheby’s London.
A Yorkshire native, Hockney took to the Woldgate Woods in 2006, painting en plein air throughout the seasons, documenting the changes in light and color over the course of the year. He wanted to work on a monumental scale, but the large canvases he had in mind wouldn’t fit up the stairs at his studio, so he combined a number of smaller ones.
David Hockney painting May 17th 2006, Woldgate Woods, East Yorkshire. Courtesy of Sotheby’s, photo © Jean-Pierra Goncalves de Lima, artwork © David Hockney.
Three prints of works depicting Woldgate have come to auction in recent years (two fetched under $1,000, the third went unsold), but the upcoming sale marks a first for one of the original canvases.
David Hockney, Woldgate Woods 2006(2006). Courtesy of Venator & Hanstein, Germany.
“With the opening of the Tate retrospective early next year, along with collectors’ tremendous appetite for quality, now is the perfect time to present one of the great accomplishments of the artist’s late career,” said Grégoire Billault, head of the contemporary art department, in a statement.
Ahead of the sale, Woldgate Woods will be on view at Sotheby’s London October 1–7, 2016, and at Sotheby’s New York November 4–17. Other potential big ticket items at the auction include a pair of Willem de Kooning canvases—Untitled (1976–77) and Untitled XXXIX (1983)—both of which could fetch $8 million–12 million.
Ciclesonide is used to prevent and reduce the symptoms (wheezing and shortness of breath) caused by asthma. Controlling asthma symptoms may decrease time lost from work or school. This medication belongs to a class of drugs known as corticosteroids. It works by reducing the swelling of the airways in the lungs to make breathing easier.This medication must be taken regularly to be effective. It does not work right away and should not be used to relieve sudden asthma attacks. If an asthma attack occurs, use your quick-relief inhaler as prescribed. Keep track of how often you need to use your quick-relief inhaler, and tell your doctor. If your quick-relief inhaler does not seem to work as well, if you need to use more than usual of your quick-relief inhaler for 2 or more days in a row, or if you need to use more than one full canister of your quick-relief inhaler over a 2-month period, seek immediate medical attention.
At the first European Forum Let’s Liberate Diversity! in Poitiers, France, the idea has emerged on the creation of a European network committed to the conservation and renewal of crop biodiversity in farms and gardens. First, an informal network has been established with the aim to organize exchanges among different countries / partners and develop joint strategies at the European level. The next meetings helped to crystallize the political foundations of the European network. The development of the charter containing the network?s political principles is underway.
Exchanging information and experiences between member organizations at the European level as well as partners outside of Europe, particularly in the Mediterranean region.
The 6th European forum “Let’s Liberate Diversity!” on agricultural biodiversity took place on February 25-26, 2011 in Szeged, Hungary.
The Let’s Liberate Diversity! forums are the annual gatherings of farmers’ organisations and associations working on agricultural biodiversity in Europe.
The 2011 edition of the forum will be held in Szeged, Hungary, during the Hungarian presidency of the European Union. Its central theme will be the question of Farmers’ Rights related to the conservation, sustainable use and development of agricultural biodiversity.