Mothers, Daughters, and the Transmission of Memory in Documentaries Directed by Women of Maghrebi Origin in France

This article compares the treatment of memory and the transmission of memory in Yamina Benguigui’s Mémoires d’immigrés: l’héritage maghrébin (1997) with the treatment of these themes in five other documentaries directed by Maghrebi-French women – all of which were released after Mémoires d’immigrés: Yasmina Kherfi’s Mes voisines mes copines (2002), Djamila Sfaxi’s À ma mère (2003), Rahma Benhamou El Madani’s Du côté de chez soi (2003), Soraya Nini’s 24 heures dans la Life de ma mère (2007) and Fatima Sissani’s La langue de Zahra (2011). It argues that in contrast to Benguigui’s foregrounding of collective experiences of Maghrebi migrant women in Mémoires d’immigrés, these five documentaries highlight the specificity of the memories and experiences of the directors’ mothers and in doing so problematize the very idea that there exists a collective trajectory or set of experiences with regard to Maghrebi migrants in France. When considered together, these films reflect a shift away from the universalizing and collective view of Maghrebi migration that is set forth in Benguigui’s documentary

Absence of signatures of Weyl orbits in the thickness dependence of quantum transport in cadmium arsenide

In a Weyl orbit, the Fermi arc surface states on opposite surfaces of the topological semimetal are connected through the bulk Weyl or Dirac nodes. Having a real-space component, these orbits accumulate a sample-size-dependent phase. Following recent work on the three-dimensional Dirac semimetal cadmium arsenide (Cd3As2), we have sought evidence for this thickness-dependent effect in quantum oscillations and quantum Hall plateaus in (112)-oriented Cd3As2 thin films grown by molecular beam epitaxy. We compare quantum transport in films of varying thickness at apparently identical gate-tuned carrier concentrations and find no clear dependence of the relative phase of the quantum oscillations on the sample thickness. We show that small variations in carrier densities, difficult to detect in low-field Hall measurements, lead to shifts in quantum oscillations that are commensurate with previously reported phase shifts. Future claims of Weyl orbits based on the thickness dependence of quantum transport data require additional studies that demonstrate that these competing effects have been disentangled

Observation of the quantum Hall effect in confined films of the three-dimensional Dirac semimetal Cd3As2

The magnetotransport properties of epitaxial films of Cd3As2, a paradigm three-dimensional Dirac semimetal, are investigated. We show that an energy gap opens in the bulk electronic states of sufficiently thin films and, at low temperatures, carriers residing in surface states dominate the electrical transport. The carriers in these states are sufficiently mobile to give rise to a quantized Hall effect. The sharp quantization demonstrates surface transport that is virtually free of parasitic bulk conduction and paves the way for novel quantum transport studies in this class of topological materials. Our results also demonstrate that heterostructuring approaches can be used to study and engineer quantum states in topological semimetals.Comment: Accepted, Phys. Rev. Let

Basal-plane growth of cadmium arsenide by molecular beam epitaxy

(001)-oriented thin films of the three-dimensional Dirac semimetal cadmium arsenide can realize a quantum spin Hall insulator and other kinds of topological physics, all within the flexible architecture of epitaxial heterostructures. Here, we report a method for growing (001) cadmium arsenide films using molecular beam epitaxy. The introduction of a thin indium arsenide wetting layer improves surface morphology and structural characteristics, as measured by x-ray diffraction and reflectivity, atomic force microscopy, and scanning transmission electron microscopy. The electron mobility of 50-nm-thick films is found to be 9300 cm2/Vs at 2 K, comparable to the highest-quality films grown in the conventional (112) orientation. This work demonstrates a simple experimental framework for exploring topological phases that are predicted to exist in proximity to the three-dimensional Dirac semimetal phase

Electron energy analysis by phase-space shaping with THz field cycles

Time-resolved electron energy analysis and loss spectroscopy can reveal a wealth of information about material properties and dynamical light-matter interactions. Here, we report an all-optical concept for measuring energy spectra of femtosecond electron pulses with sub-eV resolution. Laser-generated terahertz radiation is used to measure arrival time differences within electron pulses with few-femtosecond precision. Controlled dispersion and subsequent compression of the electron pulses provide almost any desired compromise of energy resolution, signal strength, and time resolution. A proof-of-concept experiment on aluminum reveals an energy resolution of <3.5 eV (rms) at 70-keV after a drift distance of only 0.5 m. Simulations of a two-stage scheme reveal that pre-stretched pulses can be used to achieve <10 meV resolution, independent of the source's initial energy spread and limited only by the achievable THz field strength and measuring time

A spatially and temporally localized sub-laser-cycle electron source

We present an experimental and numerical study of electron emission from a sharp tungsten tip triggered by sub-8 femtosecond low power laser pulses. This process is non-linear in the laser electric field, and the non-linearity can be tuned via the DC voltage applied to the tip. Numerical simulations of this system show that electron emission takes place within less than one optical period of the exciting laser pulse, so that an 8 fsec 800 nm laser pulse is capable of producing a single electron pulse of less than 1 fsec duration. Furthermore, we find that the carrier-envelope phase dependence of the emission process is smaller than 0.1% for an 8 fsec pulse but is steeply increasing with decreasing laser pulse duration.Comment: 4 pages, 5 figure

THE IMPACT OF STATE HEALTH INSURANCE PARITY LAWS ON INITIATION OF SUBSTANCE USE DISORDER TREATMENT

Statement of Problem: The implementation of the Patient Protection and Affordable Care Act (PPACA) of 2010 is expected to change the Substance Use Disorder (SUD) treatment system drastically through its expansion of federal parity protections on mental health and SUD benefits. However, the impact of previously existent state-specific parity laws on access to and use of SUD treatment has not been fully explored. In this study, we aim to compare initiation of substance use treatment between individuals in states with and without SUD parity laws in the year 2001, using longitudinal data from two waves of the National Epidemiologic Survey on Alcohol and Related Conditions that took place respectively in 2001-2002 and 2004-2005. Methods: Stabilized inverse probability of treatment weights were used in conjunction with survey weights to adjust for potential confounders. Logistic regression models were then used to compare odds of treatment initiation among individuals reporting past year substance use (but no past year substance use treatment) in states with SUD parity laws compared to states with no laws. Sub-analyses were performed to focus on individuals with lifetime history of SUD as well as to analyze separately alcohol users and other substance users. Results: Individuals reporting past year substance use at baseline in parity states had a 1.55 higher odds of treatment initiation than those in states without SUD parity (95% CI: 0.63-3.81). Individuals with lifetime history of SUD at baseline in parity states and current substance use had a 1.69 higher odds of treatment initiation than those in states without SUD parity (95% CI: 0.81-3.54). Individuals with lifetime history of AUD (no other SUDs) at baseline in parity states and current substance use had a 4.61 higher odds of treatment initiation than those in states without SUD parity (95% CI: 1.27-16.77). Conclusions: Parity was only associated with significantly higher odds of SUD treatment initiation among those with lifetime history of AUD and current substance use. Advisor: Rosa Crum, MHA, MD Reader: Ramin Mojtabai, PhD, MPH, M

Exchange biased anomalous Hall effect driven by frustration in a magnetic kagome lattice.

Co[Formula: see text]Sn[Formula: see text]S[Formula: see text] is a ferromagnetic Weyl semimetal that has been the subject of intense scientific interest due to its large anomalous Hall effect. We show that the coupling of this material's topological properties to its magnetic texture leads to a strongly exchange biased anomalous Hall effect. We argue that this is likely caused by the coexistence of ferromagnetism and geometric frustration intrinsic to the kagome network of magnetic ions, giving rise to spin-glass behavior and an exchange bias

Anomalous superconducting diode effect in a polar superconductor

A superconductor with broken time reversal and inversion symmetry may exhibit nonreciprocal charge transport, including a nonreciprocal critical current, also known as superconducting diode effect. We report an intrinsic superconducting diode effect in a polar strontium titanate film. Differential resistance measurements reveal a superconducting state whose depairing current is polarity dependent. There is, however, no measurable deviation from Ohmic behavior, implying that this state does not arise from a bulk magnetochiral anisotropy. In the entire measurement range, the only deviation from linearity in the differential resistance is on the edge of the superconducting transition at high magnetic fields, likely due to the motion of flux vortices. Furthermore, the magnitude of the effect is preserved even when the in-plane magnetic field is oriented parallel to the current, indicating that this effect truly does not originate from a bulk magnetochiral anisotropy