Nov pogled na spomenike v pokrajini Črnega pasu: načrtovanje, spomin in identiteta Afroameričanov v Alabami

Čeprav so mnogi stari kraji v ZDA dobro ohranjeni, veliko območij zgodovinske in kulturne vrednosti zaradi opuščanja izginja. V nekaterih primerih imajo restavratorji zaradi stanja teh krajev težko delo, v drugih primerih pa uprave in kulturne ustanove za izboljšanje lokalnega gospodarstva uvajajo strateške prostorske načrte, s katerimi želijo pritegniti turiste in urediti zgodovinske tematske parke. Novejše raziskave odnosa med zgodovino in kolektivnim spominom pa so ta območja postavile pod drobnogled. Čeprav spomin za nekatera zgodovinska območja hitro izgineva, dobiva več pozornosti kot v preteklosti, s čimer se krepita lokalna identiteta in občutek pripadnosti skupnosti. V članku je obravnavano več načrtov in načrtovalskih strategij, ki so bili razviti za oblikovanje spomeniške pokrajine v Alabami, dokumentirani in preučeni pa so tudi nekateri ključni odnosi med načrtovanjem mest in obeleževanjem zgodovine Afroameričanov

Rethinking the memorial in a Black Belt landscape: Planning, memory and identity of African-Americans in Alabama

Although many old sites are well preserved, many sites of historical and cultural value in the United States are disappearing due to their abandonment. In some cases, the condition of these sites makes restorers’ work very difficult. In other cases, in order to recover blighted local economies, administrations and cultural institutions are adopting strategic spatial plans to attract tourists or accommodate historical theme parks. However, recent scholarly interest in the interaction of history and collective memory has highlighted these sites. Even if the memory of some historical sites is fading quickly, this memory is receiving greater attention than in the past in order to enhance local identity and strengthen the sense of community. This article examines a number of plans and strategies adopted to give shape to the memorial landscape in Alabama, thereby documenting and exploring some key relations between city planning and the commemoration of African-American history

An educational path for the magnetic vector potential and its physical implications

We present an educational path on the magnetic vector potential A addressed to undergraduate students and to pre-service physics teachers. Starting from the generalized Ampere-Laplace law, in the framework of a slowly varying time-dependent field approximation, the magnetic vector potential is written in terms of its empirical referent, i. e. the conduction current. Therefore, once the currents are known, our approach allows a clear and univocal physical determination of A overcoming the mathematical indeterminacy due to the gauge transformations. We have no need to fix a gauge, since for slowly varying time-dependent electric and magnetic fields, the natural gauge for A is the Coulomb one. We stress the difference between our approach and those usually presented in the literature. Finally, a physical interpretation of the magnetic vector potential is discussed and some examples of calculation of A are analysed

Modelling strains and stresses in continuously stratified rotating neutron stars

We introduce a Newtonian model for the deformations of a compressible, autogravitating, and continuously stratified neutron star. The present framework can be applied to a number of astrophysical scenarios as it allows us to account for a great variety of loading forces. In this first analysis, the model is used to study the impact of a frozen adiabatic index in the estimate of rotation-induced deformations: we assume a polytropic equation of state for the matter at equilibrium but, since chemical reactions may be slow, the perturbations with respect to the unstressed configuration are modelled by using a different adiabatic index. We quantify the impact of a departure of the adiabatic index from its equilibrium value on the stressed stellar configuration and we find that a small perturbation can cause large variations both in displacements and strains. As a first practical application, we estimate the strain developed between two large glitches in the Vela pulsar showing that, starting from an initial unstressed configuration, it is not possible to reach the breaking threshold of the crust, namely to trigger a starquake. In this sense, the hypothesis that starquakes could trigger the unpinning of superfluid vortices is challenged and, for the quake to be a possible trigger, the solid crust must never fully relax after a glitch, making the sequence of starquakes in a neutron star an history-dependent process.Comment: 16 pages, 12 figure

Examining Characteristics and Barriers on the Adoption of School Gardens among Agricultural Education Teachers

The overall purpose of this study was to understand the influence of selected factors on the adoption of school gardens by Agricultural Science teachers in Alabama. This study looked at how the relationships between characteristics of teachers, characteristics of innovation, and barriers to adoption affected the diffusion of school gardens. A random sample of 117 Agricultural Science teachers was selected for participation in the study. A majority of Agricultural Science teachers reported they were in the confirmation/implementation stage (40.5%); 4% had no knowledge of the innovation; 6% were in the persuasion stage; 4% were in the decision stage. Overall, Agricultural Science teachers showed a positive attitude toward school gardens. Agricultural Education teachers perceived two primary barriers to the adoption of school gardens. Removing these barriers, time constraints and lack of financial support, would be expected to positively affect the rate of adoption. Based on these findings, offering monetary incentives may increase the rate of adoption, and decrease teachers’ financial concerns. These findings show that female teachers have a more positive attitude towards school gardens, compared to males. Allotting more resources to the hands of female teachers, and including them in the decision-making process about school garden sustainability, may increase school garden diffusion

Out-of-equilibrium collective oscillation as phonon condensation in a model protein

In the first part of the present paper (theoretical), the activation of out-of-equilibrium collective oscillations of a macromolecule is described as a classical phonon condensation phenomenon. If a macromolecule is modeled as an open system, that is, it is subjected to an external energy supply and is in contact with a thermal bath to dissipate the excess energy, the internal nonlinear couplings among the normal modes make the system undergo a non-equilibrium phase transition when the energy input rate exceeds a threshold value. This transition takes place between a state where the energy is incoherently distributed among the normal modes, to a state where the input energy is channeled into the lowest frequency mode entailing a coherent oscillation of the entire molecule. The model put forward in the present work is derived as the classical counterpart of a quantum model proposed long time ago by H. Fr\"ohlich in the attempt to explain the huge speed of enzymatic reactions. In the second part of the present paper (experimental), we show that such a phenomenon is actually possible. Two different and complementary THz near-field spectroscopic techniques, a plasmonic rectenna, and a micro-wire near-field probe, have been used in two different labs to get rid of artefacts. By considering a aqueous solution of a model protein, the BSA (Bovine Serum Albumin), we found that this protein displays a remarkable absorption feature around 0.314 THz, when driven in a stationary out-of-thermal equilibrium state by means of optical pumping. The experimental outcomes are in very good qualitative agreement with the theory developed in the first part, and in excellent quantitative agreement with a theoretical result allowing to identify the observed spectral feature with a collective oscillation of the entire molecule.Comment: 49 pages, 10 figures; Physical Review X, (2018) in pres

n-Ge on Si for Mid-Infrared Plasmonic Sensors

The detection and amplification of molecular absorption lines from a mustard gas simulant is demonstrated using plasmonic antennas fabricated from n-Ge epitaxially grown on Si. Approaches to integrated sensors will be presented along with a review of n-Ge compared to other mid-infrared plasmonic materials

Old Quantum Physics for Cultural Education

Personal culture can be considered as that rich knowledge that makes people able of a broad vision, new ideas, and personal reflections about reality. With social culture, instead, we mean those habits, values and behaviours adopted by a given society. But we can also consider disciplinary culture, i.e., the one “identified” by a disciplinarily differentiated group, like physicists. It is from this last point of view that often scientists complain of a lack of diffuse scientific culture. This fact comes from the observation that, indeed, few people think physics is able to touch, besides people’s minds, also people’s hearts. However, even scientists themselves rarely wonder why, and in what sense, science should really be a cultural part of the whole society. The Physics Education Research Group of the University of Milan strongly believes that awareness of the importance of cultural aspects of physics should be highlighted, and placed at the base of physics education. In this talk, we will mainly focus on our work on the historical-philosophical-educational aspects related to the birth of quantum physics, the challenges it generates and the perspectives it opens up for a general overview of the problem. We will discuss motivations, proposed methods, and tools to manifest physics as culturally strongly intertwined with the vision of the world and of life of each of us

“I (critically) think, therefore I am”: Thomson’s atomic model and the ineffectiveness of physics education

INTRODUCTION In 1904, Thomson proposed an accurate atomic model (Thomson, 1904), with a precise geometrical structure, intended as a heuristic device and aimed to explain the stability and unity of atomic phenomena, both from a chemical and electrical point of view. Therefore, the plum pudding image - commonly used in textbooks (Walker, 2017; Amaldi, 2020; Halliday, 2021; Cutnell, 2022) and familiar to teachers and students, but never used by Thomson - is due to a deep conceptual misunderstanding or perhaps to a teasing of the model. A WIDESPREAD LACK OF CRITICAL THINKING In physics courses, Thomson’s model is presented after electrostatic issues and described as a spherical distribution of positive charge with electrons randomly arranged in it (as the plums in an alleged “plum pudding”); nevertheless, the awareness that such a configuration cannot be in stable conditions unexpectedly does not arise, showing a widespread failure in using electrostatic knowledge previously acquired in a different context. Moreover, it is known that accelerated charges emit and therefore a stable planetary model cannot be possible. Thomson's model - which supposes electrons in motion, to obtain stable configurations - clearly shows the inaccuracy of this absolute statement: the problem is not the emission, but rather its amount (since collisions can provide a way to regain small energy losses). It is therefore necessary to become aware that, without calculations, the merely qualitative aspects can be misleading. Students and teachers do not usually question themselves how a model proposed by a great physicist - as Thomson was, having won the Nobel Prize in 1906 - could only be an inconsistent qualitative pattern, rather than a rigorous mathematical structure, capable of both explaining phenomena and making predictions. This lack of critical thinking compromises the foundations of physics education, and asks for careful considerations about the real effectiveness of actual physics courses in schools and universities. In this work that we are presenting, we will deal with this theme, which is not an isolated case, since also in other situations (like while dealing with the photoelectric effect and the Compton effect) coherency problems at an elementary level appear, showing the inefficacy of physics education in creating the mental conceptual structures required to critically analyse what is usually taught and learned. REFERENCES Amaldi, U. (2020). Il nuovo Amaldi per i licei scientifici blu (Vol.3). Bologna: Zanichelli. Cutnell, J. D., Johnson, K. W., & Young, D. (2022). Physics: International Adaptation (12th ed.). Hoboken, NJ: Wiley. Halliday, D., & Resnick, R. (2021). Fundamentals of Physics (12th ed.). Hoboken, NJ: Wiley. Thomson, J. J. (1904) On the Structure of the Atom. Philosophical Magazine, 7(39), 237-265. Walker, J. S. (2017). Physics (5th ed.). Bellingham, WA: Western Washington University