The municipal archives of the City of New York

Ith some 100,000 cubic feet of civic documents, vital and building records, libers, films and photographs, New York City's Municipal Archives is a magnet for researchers. Among those who benefit from centralized access to the wealth of material deposited in the Archives by city government agencies are genealogists, urban scholars and architectural historians

Leaving Home: What Economics Has to Say about the Living Arrangements of Young Australians

Like their counterparts elsewhere, more young Australians than ever are delaying the move to establish residential independence from their parents. This paper reviews the developing economics literature surrounding young people’s decisions to continue living in their parents’ homes in order to begin to assess the causes and consequences of this decision. In particular, co-residence with parents appears to be an important form of intergenerational support for young adults. It is important to understand the extent to which young people rely on this form of support as they complete their education, enter the labour market, and establish themselves as independent adults. Specific attention is paid to the ways in which Australian income-support, education, and housing policies may influence these patterns.household decision-making, economics of the family

Using an Online Sample to Estimate the Size of an Offline Population.

Online data sources offer tremendous promise to demography and other social sciences, but researchers worry that the group of people who are represented in online data sets can be different from the general population. We show that by sampling and anonymously interviewing people who are online, researchers can learn about both people who are online and people who are offline. Our approach is based on the insight that people everywhere are connected through in-person social networks, such as kin, friendship, and contact networks. We illustrate how this insight can be used to derive an estimator for tracking the digital divide in access to the Internet, an increasingly important dimension of population inequality in the modern world. We conducted a large-scale empirical test of our approach, using an online sample to estimate Internet adoption in five countries (n ≈ 15,000). Our test embedded a randomized experiment whose results can help design future studies. Our approach could be adapted to many other settings, offering one way to overcome some of the major challenges facing demographers in the information age

Investigation of the excited state iodine lifetime in the photodissociation of perfluoroalkyl iodides

An evaluation of prospective laser materials for a space-based solar pumped laser system over the past decade has resulted in the identification of the iodine photodissociation laser as that system best suited to solar-pumped high energy operation. The active medium for the solar-pumped iodine photodissociation laser is from the family of perfluoroalkyl iodides. These lasants have the general form C(n)F(2n + 1)I, often abbreviated as RI. These iodides are known to exhibit photodissociaiton of the C-I bond when irradiated by near UV photons. The focus was on the experimental determination of the lifetime of the excited iodine atom following photodissociation of C4F9I, and also to monitor fluorescence from the iodine molecule at 500 nm to determine if I2 is being produced in the process. Photodissociation is achieved using an XeCl excimer laser with an output wavelength of 308 nm. The XeCl beam is focused into the middle of a cylindrical quartz cell containing the lasant. The laser pulse is detected with a fast risetime photomultiplier tube as it exits the cell. Other aspects of the investigation are discussed

Optimal Trajectories For Orbital Transfers Using Low And Medium Thrust Propulsion Systems

For many problems it is reasonable to expect that the minimum time solution is also the minimum fuel solution. However, if one allows the propulsion system to be turned off and back on, it is clear that these two solutions may differ. In general, high thrust transfers resemble the well-known impulsive transfers where the burn arcs are of very short duration. The low and medium thrust transfers differ in that their thrust acceleration levels yield longer burn arcs which will require more revolutions, thus making the low thrust transfer computational intensive. Here, we consider optimal low and medium thrust orbital transfers