Demonstration of a Multipulse Interferometer for Quantum Kicked-Rotor Studies

We implemented a multipulse interferometer scheme that allows us to study a quantum kicked rotor by observing dephasing of momentum coherence. Our study shows that momentum coherence can be nearly perfectly preserved under conditions where the mean energy as a function of the kick number is known to increase without bound. The accompanying width narrowing of these coherences may provide a new method for accurate measurement of the recoil frequency.Physic

Managed Racial Capitalism: Understanding the Bureaucratic State’s Racialized Practices in Detroit, Michigan

Public administration navigates an important place in governing in that it is multidisciplinary and focused on practice, thus all theories need to be prepared to face critique from the people. At this watershed moment of social justice, political reckoning, and revolutionary imagination, it is key that public administration contends with the racist logics driving the field and the practice. In this article, we examine the ways that the current governing system fails to account for the racialized political economy, thus reproducing the inequality inherent in that system. The paper poses two questions: 1) How does the public administration of local governments reproduce inequality? And 2) How can we rethink public administration through a system of governing that intentionally engages with and rectifies racialized practices? We argue that late-stage capitalism, manifested as neoliberalism, is always racialized. We propose a manageable possibility of community-focused engagement and deliberation

FreedomCAR - Aftertreatment Subsystem Development

The primary objective of this program was to develop generic aftertreatment technologies applicable for LDV and LDT engines ranging from 55 kW to 200kW, to develop an optimized and integrated aftertreatment system for a LDT (Light Duty Truck) type vehicle, and to demonstrate the technology which will enable light duty diesel engines to meet Federal Tier II regulation with minimum impact on fuel economy. Specifically, the development targets for emissions reduction and fuel injection penalty are given below: (1) NOx conversion efficiency > 90% (hot), > 84% (combined); (2) PM conversion efficiency > 90% (hot), > 84% (combined); (3) Fuel penalty over FTP-75 Less than 5%; and (4) Fuel penalty at Cruise condition Less than 3%. Development of cost-effective, highly efficient diesel exhaust aftertreatment systems in combination with very low engine out emission combustion development are essential elements for realization of Federal Tier II emission standards for Light Duty Trucks and Vehicles. Evaluation of several aftertreatment technologies was completed as part of this program. A combination of Diesel Oxidation Catalyst, NOx Adsorbing Catalyst and Catalyzed Soot Filter was found to provide the levels of conversion efficiency required to achieve the emission targets. While early systems required relatively large catalyst volumes, external dosing, sulfur traps, full bypass configurations and high levels of Platinum metals; the final system is a compact, scalable, flow-through, fully-integrated and engine-managed aftertreatment system capable of commercial application for Light Duty Vehicles and Trucks. NOx adsorber/particulate filter technology is particularly attractive for Light Duty applications due to the lower exhaust flow and temperature requirements as compared to Heavy Duty engines. Despite these strong positive aspects, NOx Adsorbers are challenged by their regeneration requirements and susceptibility to sulfur poisoning and thermal degradation. Capability was developed to regenerate the NOx Adsorber for NOx and SOx as well as the Particulate Filter for soot. This system was fully integrated into a truck and evaluated over the chassis dynamometer for emissions capability and in real-world winter field testing. Durability of the system was evaluated over a variety of accelerated and real-time dynamometer tests. Excellent NOx and PM conversion efficiency was demonstrated, even following 3000 hrs of endurance testing. Unregulated emissions emitted by the system were evaluated as was the fuel penalty associated with the DeNOx and DeSOx regeneration processes. In the final evaluation, the system demonstrated 90% NOx conversion and 99% PM conversion at a 6% fuel penalty over the FTP-75 test cycle. While target fuel penalty levels were demonstrated using full-bypass configuration systems, the cost associated with those systems was prohibitively high and would preclude successful commercialization of the technology. Although the flow-through configuration fell 1% short of the 5% fuel penalty target, the cost of this configuration is such that commercial application is feasible. Cost drivers for the final system configuration were identified and demonstrate areas where future development areas could focus

An Atom Michelson Interferometer on a Chip Using a Bose-Einstein Condensate

An atom Michelson interferometer is implemented on an "atom chip." The chip uses lithographically patterned conductors and external magnetic fields to produce and guide a Bose-Einstein condensate. Splitting, reflecting, and recombining of condensate atoms are achieved by a standing-wave light field having a wave vector aligned along the atom waveguide. A differential phase shift between the two arms of the interferometer is introduced by either a magnetic-field gradient or with an initial condensate velocity. Interference contrast is still observable at 20% with atom propagation time of 10 ms

M.C. Perry letter to Acting Sailing Master, George A. Prentiss. New York, 1834.

Master Commander M. C. Perry orders Acting Sailing Master George A. Prentiss to report to the Commanding Office of the Receiving Ships for performing duty on board that vessel, dated February 4, 1834.https://digitalcommons.wofford.edu/littlejohnmss/1207/thumbnail.jp

Evolution of the Okvik/Old Bering Sea culture of the Bering Strait as a major transition

Great transitions are thought to embody major shifts in locus of selection,labour diversification and communication systems. Such expectations arerelevant for biological and cultural systems as decades of research hasdemonstrated similar dynamics within the evolution of culture. The evolutionof the Neo-Inuit cultural tradition in the Bering Strait provides anideal context for examination of cultural transitions. The Okvik/OldBering Sea (Okvik/OBS) culture of Bering Strait is the first representativeof the Neo-Inuit tradition. Archaeological evidence drawn for settlementand subsistence data, technological traditions and mortuary contextssuggests that Okvik/OBS fits the definition of a major transition givenchange in the nature of group membership (from families to politicalgroups with social ranking), task organization (emergent labour specialization)and communication (advent of complex art forms conveying socialand ideological information). This permits us to develop a number of implications about the evolutionary process recognizing that transitions mayoccur on three scales: (1) ephemeral variants, as for example, simple technological entities; (2) integrated systems, spanning modular technology tosocio-economic strategies; and (3) simultaneous change across all scaleswith emergent properties.This article is part of the theme issue ‘Human socio-cultural evolution inlight of evolutionary transitions’

Dynamical Instability of a Doubly Quantized Vortex in a Bose-Einstein condensate

Doubly quantized vortices were topologically imprinted in $|F=1>$ $^{23}$Na condensates, and their time evolution was observed using a tomographic imaging technique. The decay into two singly quantized vortices was characterized and attributed to dynamical instability. The time scale of the splitting process was found to be longer at higher atom density.Comment: 5 pages, 4 figure

Long Phase Coherence Time and Number Squeezing of two Bose-Einstein Condensates on an Atom Chip

We measured the relative phase of two Bose-Einstein condensates confined in an radio frequency induced double well potential on an atom chip. We observed phase coherence between the separated condensates for times up to 200 ms after splitting, a factor of 10 beyond the phase diffusion limit expected for a coherent state in our experimental conditions (20 ms). The enhanced coherence time is attributed to number squeezing of the initial state by a factor of 10. In addition, we demonstrated a rotationally sensitive (Sagnac) geometry for a guided atom interferometer by propagating the split condensates.Comment: 5 pages, 5 figure