Black Women in the Black Metropolis of the Early Twentieth Century: The Case of Professional Occupations

Little research has examined the employment of Black women as teachers, nurses, and librarians in the urban Black communities of the early twentieth century. The present study fills this void, analyzing Census data on the largest urban Black communities at the start of the Great Migration to cities. The results show that, in spite of the supposed advantages of the northern Black Metropolis, Black communities in the urban North were relatively limited in their potential to offer opportunities for Black women to enter pursuits that were, at the time, mainstays of a nascent class of Black professional women

Review of \u3cem\u3eImmigrants Out: The New Nativism and the Anti-Immigrant Impulse in the United States.\u3c/em\u3e Juan E Perea. Reviewed by Robert L. Boyd, Mississippi State University.

Juan E Perea, Immigrants Out: The New Nativism and the Anti-Immigrant Impulse in the United States. New York: New York University Press, 1997. $ 19.95 papercover

Review of \u3cem\u3eGlobal Decisions, Local Collisions: Urban Life in the New World Order.\u3c/em\u3e David Ranney. Reviewed by Robert L. Boyd.

Book review of David Ranney, Global Decisions, Local Collisions: Urban Life in the New World Order. Philadelphia: Temple University Press, 2003. $69.50 paperback

Black Women in the Black Metropolis of the Early Twentieth Century: The Case of Professional Occupations

Little research has examined the employment of Black women as teachers, nurses, and librarians in the urban Black communities of the early twentieth century. The present study fills this void, analyzing Census data on the largest urban Black communities at the start of the Great Migration to cities. The results show that, in spite of the supposed advantages of the northern Black Metropolis, Black communities in the urban North were relatively limited in their potential to offer opportunities for Black women to enter pursuits that were, at the time, mainstays of a nascent class of Black professional women

Robust Quantum Error Correction via Convex Optimization

We present a semidefinite program optimization approach to quantum error correction that yields codes and recovery procedures that are robust against significant variations in the noise channel. Our approach allows us to optimize the encoding, recovery, or both, and is amenable to approximations that significantly improve computational cost while retaining fidelity. We illustrate our theory numerically for optimized 5-qubit codes, using the standard [5,1,3] code as a benchmark. Our optimized encoding and recovery yields fidelities that are uniformly higher by 1-2 orders of magnitude against random unitary weight-2 errors compared to the [5,1,3] code with standard recovery. We observe similar improvement for a 4-qubit decoherence-free subspace code.Comment: 4 pages, including 3 figures. v2: new example

Cultural Innovations and Demographic Change

Demography plays a large role in cultural evolution through its effects on the effective rate of innovation. If we assume that useful inventions are rare, then small isolated societies will have low rates of invention. In small populations, complex technology will tend to be lost as a result of random loss or incomplete transmission (the Tasmanian effect). Large populations have more inventors and are more resistant to loss by chance. If human populations can grow freely, then a population-technology-population positive feedback should occur such that human societies reach a stable growth path on which the rate of growth of technology is limited by the rate of invention. This scenario fits the Holocene to a first approximation, but the late Pleistocene is great puzzle. Large-brained hominins existed in Africa and west Eurasia of perhaps 150,000 years with, at best, slow rates of technical innovation. The most sophisticated societies of the last glacial period appear after 50,000 years ago and were apparently restricted to west and north-central Eurasia and North Africa. These patterns have no simple, commonly accepted explanation. We argue that increased high-frequency climate change around 70,000–50,000 years ago may have tipped the balance between humans and their competitor- predators, such as lions and wolves, in favor of humans. At the same time, technically sophisticated hunters would tend to overharvest their prey. Perhaps the ephemeral appearance of complex tools and symbolic artifacts in Africa after 100,000 years ago resulted from hunting inventions that allowed human populations to expand temporarily before prey over exploitation led to human population and technology collapse. Sustained human populations of moderate size using distinctively advanced Upper Paleolithic artifacts may have existed in west Eurasia because cold, continental northeastern Eurasia–Beringia acted as a protected reserve for prey populations

LANDOWNER ATTITUDES REGARDING PENNSYLVANIA\u27S EXTENDED ANTERLESS DEER SEASON ON DEER-DAMAGED FARMS

The Pennsylvania Game Commission authorized an extension of the 1990-1991 anterless white-tailed deer (Odocoileus virginianus) season to reduce deer abundance on farms having excessive crop damage. A mail survey of the 574 participating landowners was conducted to assess the effectiveness of the program. After 2 mailings 93% (n = 531) responded, and 444 returns had completed information for numbers of hunters, hectares, and harvested deer. Based on landowner responses, an estimated 2,674 deer were harvested by 35,181 hunters on 58,525 ha. An average of 4.6 deer were harvested/km2 of huntable land, which compared to a statewide estimate of f2.3 deer harvested/km2 during the 1990 4-day regular anterless-deer season. Twenty-four percent (n = 107) of respondents reported zero deer harvested. Twenty-five percent of respondents (n = 110) were satisfied with the program. Landowners who were dissatisfied (n = 331, 75%) could provide up to 5 reasons for dissatisfaction. Four hundred sixty-nine responses were provided. Three-hundred-forty-seven responses (74%) indicated too few deer were killed, while 23% (n = 106) indicated that the program was inconvenient. Satisfaction related to number and density of deer harvested, hectares of huntable land, perception of hunter density, and suggested improvements. Many respondents (n = 204, 46%)indicated they would participate again, in spite of the high degree of dissatisfaction. Number and density of deer harvested, density of hunters, perception of hunter density, satisfaction, and reason for dissatisfaction, were related to willingness to participate again. Landowner suggestions for improvements (5 allowed per respondent, n = 364 recieved) centered on harvesting more deer by involving more land (n = 201, 55%) and moving the timing of the season (n = 119, 33%). Seventy-two percent (n = 320) of responses (5 allowed per respondent, n = 625 recieved) indicated neighboring posted land was the primary reason for too many deer on their property. This remains the greatest challenge in providing relief from high deer densities

Supersensitive measurement of angular displacements using entangled photons

We show that the use of entangled photons having non-zero orbital angular momentum (OAM) increases the resolution and sensitivity of angular-displacement measurements performed using an interferometer. By employing a 4$\times$4 matrix formulation to study the propagation of entangled OAM modes, we analyze measurement schemes for two and four entangled photons and obtain explicit expressions for the resolution and sensitivity in these schemes. We find that the resolution of angular-displacement measurements scales as $Nl$ while the angular sensitivity increases as $1/(2Nl)$, where $N$ is the number of entangled photons and $l$ the magnitude of the orbital-angular-momentum mode index. These results are an improvement over what could be obtained with $N$ non-entangled photons carrying an orbital angular momentum of $l\hbar$ per photonComment: 6 pages, 3 figure

Experimental investigation of high-dimensional quantum key distribution protocols with twisted photons

Quantum key distribution is on the verge of real world applications, where perfectly secure information can be distributed among multiple parties. Several quantum cryptographic protocols have been theoretically proposed and independently realized in different experimental conditions. Here, we develop an experimental platform based on high-dimensional orbital angular momentum states of single photons that enables implementation of multiple quantum key distribution protocols with a single experimental apparatus. Our versatile approach allows us to experimentally survey different classes of quantum key distribution techniques, such as the 1984 Bennett \& Brassard (BB84), tomographic protocols including the six-state and the Singapore protocol, and to investigate, for the first time, a recently introduced differential phase shift (Chau15) protocol using twisted photons. This enables us to experimentally compare the performance of these techniques and discuss their benefits and deficiencies in terms of noise tolerance in different dimensions.Comment: 13 pages, 4 figures, 1 tabl