Walls, enclaves and the (counter) politics of design

This paper focuses on the political role of urban design in the transformation of urban and rural, central and peripheral, formal and informal landscapes in Israel. Based on design anthropology methodology, the political role of urban design in the production of aesthetic objects and landscapes that signify the control over individuals and communities will be explored. As this paper suggests, such a new form of political influence is hidden beneath an aesthetic and user-oriented façade, making it even more dangerous than previous more direct actions, such as gated communities separated from public space by stone walls. The paper’s interdisciplinary approach that is rooted in anthropology, design, architecture and politics will also point out some similarities between specific sites that are often considered different, namely Tel Aviv’s global and privatized gated communities on the one hand and the unrecognized Bedouin villages in the peripheral Negev region on the other. It will be argued that these similarities are the product of the politics of militarization, privatization and social fragmentation that are translated into urban design practices from ‘above’ via state and municipal planning policy as well as formal design, and from ‘below’ through informal and often unauthorized construction initiated by marginalized communities

Technopolitics, Development and the Colonial-Postcolonial Nexus: Revisiting Settlements Development Aid from Israel to Africa

This article focuses on the interrelationship between colonial development in Israel and the export of knowledge and practices to Africa. We argue that at the core of the Israeli aid project to Africa is the Cold War and the global technopolitics of this era, that is, the use of technological methods and practices to achieve political ends. The main question to be discussed throughout this article is whether the Zionist settlement enterprise and its ‘export’ to Africa is not only a unique historical event but rather is part of the global imperial debate. We point to the way in which the technopolitics of development in Israel is directly related to the concepts prevalent in the country during the period under discussion in several interrelated ways. First, it was embedded in an Orientalist discourse in which the ‘backward native’ becomes a consumer of modern technologies migrating from a territory where knowledge is produced to the territories that consume its products. Second, the view of Africa was part of a wider epistemological system in which orientalism was also ‘inward’ both toward the Jewish Mizrahi population and to the Palestinian population

The State of Addis Ababa 2021: Towards a Healthier City

The 'State of Addis Vol. II: Toward a healthier city' was written by an international multidisciplinary team, as the pandemic was unfolding. The report assesses the relationship between urban form and function and the spread of the COVID-19 pandemic, in Addis Ababa. It explores what is meant by a healthy city, and why planning for and investing in a healthy city, matters to Addis Ababa. It goes on to investigate the state of health, urban infrastructure and social services in the city. The socio-economic and health impacts of the pandemic are also explored further, together with the institutional response to the public health emergency. The findings provide insights on the role of urban form and infrastructure to urban health and urban resilience. Finally, the authors highlight a post-pandemic agenda for a healthier, more resilient city

From Tomonaga-Luttinger to Fermi liquid in transport through a tunneling barrier

Finite length of a one channel wire results in crossover from a Tomonaga-Luttinger to Fermi liquid behavior with lowering energy scale. In condition that voltage drop $(V)$ mostly occurs across a tunnel barrier inside the wire we found coefficients of temperature/voltage expansion of low energy conductance as a function of constant of interaction, right and left traversal times. At higher voltage the finite length contribution exhibits oscillations related to both traversal times and becomes a slowly decaying correction to the scale-invariant $V^{1/g-1}$ dependence of the conductance.Comment: 12 pages of RevTex file and 1 PS file figur

Threshold features in transport through a 1D constriction

Suppression of electron current $\Delta I$ through a 1D channel of length $L$ connecting two Fermi liquid reservoirs is studied taking into account the Umklapp electron-electron interaction induced by a periodic potential. This interaction causes Hubbard gaps $E_H$ for $L \to \infty$. In the perturbative regime where $E_H \ll v_c/L$ ($v_c:$ charge velocity), and for small deviations $\delta n$ of the electron density from its commensurate values $- \Delta I/V$ can diverge with some exponent as voltage or temperature $V,T$ decreases above $E_c=max(v_c/L,v_c \delta n)$, while it goes to zero below $E_c$. This results in a nonmonotonous behavior of the conductance.Comment: Final variant published in PRL, 79, 1714; minor correction

Hard Instances of the Constrained Discrete Logarithm Problem

The discrete logarithm problem (DLP) generalizes to the constrained DLP, where the secret exponent $x$ belongs to a set known to the attacker. The complexity of generic algorithms for solving the constrained DLP depends on the choice of the set. Motivated by cryptographic applications, we study sets with succinct representation for which the constrained DLP is hard. We draw on earlier results due to Erd\"os et al. and Schnorr, develop geometric tools such as generalized Menelaus' theorem for proving lower bounds on the complexity of the constrained DLP, and construct sets with succinct representation with provable non-trivial lower bounds

Kondo resonance effect on persistent currents through a quantum dot in a mesoscopic ring

The persistent current through a quantum dot inserted in a mesoscopic ring of length L is studied. A cluster representing the dot and its vicinity is exactly diagonalized and embedded into the rest of the ring. The Kondo resonance provides a new channel for the current to flow. It is shown that due to scaling properties, the persistent current at the Kondo regime is enhanced relative to the current flowing either when the dot is at resonance or along a perfect ring of same length. In the Kondo regime the current scales as $L^{-1/2}$, unlike the $L^{-1}$ scaling of a perfect ring. We discuss the possibility of detection of the Kondo effect by means of a persistent current measurement.Comment: 11 pages, 3 Postscript figure

Is there a d.c. Josephson Effect in Bilayer Quantum Hall Systems?

We argue on the basis of phenomenological and microscopic considerations that there is no d.c. Josephson effect in ordered bilayer quantum Hall systems, even at T=0. Instead the tunnel conductance is strongly enhanced, approaching a finite value proportional to the square of the order parameter as the interlayer tunneling amplitude vanishes.Comment: 5 pages, 2 figure

Fractional charge in transport through a 1D correlated insulator of finite length

Transport through a one channel wire of length $L$ confined between two leads is examined when the 1D electron system has an energy gap $2M$: $M > T_L \equiv v_c/L$ induced by the interaction in charge mode ($v_c$: charge velocity in the wire). In spinless case the transformation of the leads electrons into the charge density wave solitons of fractional charge $q$ entails a non-trivial low energy crossover from the Fermi liquid behavior below the crossover energy $T_x \propto \sqrt{T_L M} e^{-M /[T_L(1-q^2)]}$ to the insulator one with the fractional charge in current vs. voltage, conductance vs. temperature, and in shot noise. Similar behavior is predicted for the Mott insulator of filling factor $\nu = integer/(2 m')$.Comment: 5 twocolumn pages in RevTex, no figure

Bias and temperature dependence of the 0.7 conductance anomaly in Quantum Point Contacts

The 0.7 (2e^2/h) conductance anomaly is studied in strongly confined, etched GaAs/GaAlAs quantum point contacts, by measuring the differential conductance as a function of source-drain and gate bias as well as a function of temperature. We investigate in detail how, for a given gate voltage, the differential conductance depends on the finite bias voltage and find a so-called self-gating effect, which we correct for. The 0.7 anomaly at zero bias is found to evolve smoothly into a conductance plateau at 0.85 (2e^2/h) at finite bias. Varying the gate voltage the transition between the 1.0 and the 0.85 (2e^2/h) plateaus occurs for definite bias voltages, which defines a gate voltage dependent energy difference $\Delta$. This energy difference is compared with the activation temperature T_a extracted from the experimentally observed activated behavior of the 0.7 anomaly at low bias. We find \Delta = k_B T_a which lends support to the idea that the conductance anomaly is due to transmission through two conduction channels, of which the one with its subband edge \Delta below the chemical potential becomes thermally depopulated as the temperature is increased.Comment: 9 pages (RevTex) with 9 figures (some in low resolution