The Emerging Dominance of Immigrants in the US Housing Market 1970-2000

The article summarizes growth trends in occupied housing in the USA and in five individual states with the largest immigrant populations—California, New York, Florida, Texas and Illinois. The analysis covers the decades between 1970 and 2000 and documents the explosive growth of immigrant housing demand. Foreign-born households constitute increasingly large shares of total households in the USA (11 percent in 2000), especially in renter-occupied housing (17 percent in 2000). In particular, immigrants constitute much of the growth in demand and are emerging as a dominant force in the US housing market. In the 1990s, they accounted for 32 percent of all household growth and 67 percent of all rental growth nationwide. In California and New York, immigrants accounted for 100 percent of all rental growth and over half of all growth in owner-occupied housing. The article also addresses the surprisingly steep upward trajectories into homeownership as immigrants settle longer in the USA. This upward mobility occurs equally in all the gateway states for immigrant settlement.     

Antenna-Coupled Bolometer Arrays for Measurement of the Cosmic Microwave Background Polarization

We are building antenna-coupled Transition Edge Sensor bolometer arrays to measure the polarization of the cosmic microwave background. 217 GHz prototype pixels have previously been characterized and showed promising performance (Myers et al. in Appl. Phys. Lett. 86:114103, [2005]). Our design uses a double slot dipole antenna and an integrated microstrip band defining filter. New devices have been tested which include on-chip test structures to improve our understanding of detector performance and guide future development. In parallel with this, large arrays of bolometers based on the prototype pixel design have also been constructed. The array pixels are a heterogeneous mixture of single band pixels at 90 GHz, 150 GHz, and 220 GHz and now incorporate dual-polarization antennas (Chattopadhyay and Zmuidzinas in IEEE Trans. Antennas Propag. 46:736, [1998]). Preliminary results from optical testing of array pixels are presented. These bolometer arrays will be used in the upcoming CMB polarization experiment Polarbear.      

Selecting a best-fit temperature-dependent regression model for thin target HVI data

The results presented here are the culmination of a series of investigations to determine whether or not thin target hole diameters impacted from ∼2 to 7 km/s would be larger if the thin targets were subjected to elevated test temperatures. Extensive graphical and quantitative analyses were performed to determine if temperature has a statistically significant effect on the 21 hole diameters considered. Because two velocity measurement devices were used that possessed different measurement uncertainties, measures were taken to establish a statistically significant temperature effect independently of device bias and measurement uncertainty. Temperature was found to have a statistically significant effect for 12 of the data points whose velocities were collected by the laser system, but the effect was not statistically significant for the remaining nine data points whose velocities were collected by the flash X-ray system. Extensive statistical analyses also identified a best-fit model to the current data set, which is comprised by both a linear velocity term and a temperature term with a cumulative distribution functional form. Goodness-of-fit (GOF) was predominantly established by the model residual standard deviation, but a variety of graphical and analytical statistical tests were applied to support the conclusion. GOF statistics for the two best-fit, temperature-dependent regression models provided further support for the significance of the temperature term.     

Learning and generalization deficits in patients with memory impairments due to anterior communicating artery aneurysm rupture or hypoxic brain injury.

[Correction Notice: An erratum for this article was reported in Vol 22(6) of Neuropsychology (see record 2008-15268-012). Author Ramona O. Hopkins's name was misspelled as Romona O. Hopkins.] Human anterograde amnesia can result from a variety of etiologies, including hypoxic brain injury and anterior communicating artery (ACoA) aneurysm rupture. Although each etiology can cause a similarly severe disruption in declarative memory for verbal and visual material, there may be differences in incrementally acquired, feedback-based learning, as well as generalization. Here, 6 individuals who survived hypoxic brain injury, 7 individuals who survived ACoA aneurysm rupture, and 13 matched controls were tested on 2 tasks that included a feedback-based learning phase followed by a transfer phase in which familiar information is presented in new ways. In both tasks, the ACoA group was slow on initial learning, but those patients who completed the learning phase went on to transfer as well as controls. In the hypoxic group, 1 patient failed to complete either task; the remaining hypoxic group did not differ from controls during learning of either task, but was impaired on transfer. These results highlight a difference in feedback-based learning in 2 amnesic etiologies, despite similar levels of declarative memory impairment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

"Learning and generalization deficits in patients with memory impairments due to anterior communicating artery aneurysm rupture or hypoxic brain injury": Correction.

Reports an error in "Learning and generalization deficits in patients with memory impairments due to anterior communicating artery aneurysm rupture or hypoxic brain injury" by Catherine E. Myers, Ramona O. Hopkins, John DeLuca, Nancy B. Moore, Leo J. Wolansky, Jennifer M. Sumner and Mark A. Gluck (Neuropsychology, 2008[Sep], Vol 22[5], 681-686). Author Ramona O. Hopkins's name was misspelled as Romona O. Hopkins. (The following abstract of the original article appeared in record 2008-11707-013.) Human anterograde amnesia can result from a variety of etiologies, including hypoxic brain injury and anterior communicating artery (ACoA) aneurysm rupture. Although each etiology can cause a similarly severe disruption in declarative memory for verbal and visual material, there may be differences in incrementally acquired, feedback-based learning, as well as generalization. Here, 6 individuals who survived hypoxic brain injury, 7 individuals who survived ACoA aneurysm rupture, and 13 matched controls were tested on 2 tasks that included a feedback-based learning phase followed by a transfer phase in which familiar information is presented in new ways. In both tasks, the ACoA group was slow on initial learning, but those patients who completed the learning phase went on to transfer as well as controls. In the hypoxic group, 1 patient failed to complete either task; the remaining hypoxic group did not differ from controls during learning of either task, but was impaired on transfer. These results highlight a difference in feedback-based learning in 2 amnesic etiologies, despite similar levels of declarative memory impairment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Progress in carbon dioxide capture and separation research for gasification-based power generation point sources

The purpose of the present work is to investigate novel approaches, materials, and molecules for the abatement of carbon dioxide (CO₂) at the pre-combustion stage of gasification-based power generation point sources. The capture/separation step for CO₂ from large point sources is a critical one with respect to the technical feasibility and cost of the overall carbon sequestration scenario. For large point sources, such as those found in power generation, the carbon dioxide capture techniques being investigated by the Office of Research and Development of the National Energy Technology Laboratory possess the potential for improved efficiency and reduced costs as compared to more conventional technologies. The investigated techniques can have wide applications, but the present research is focused on the capture/separation of carbon dioxide from fuel gas (pre-combustion gas) from processes such as the Integrated Gasification Combined Cycle (IGCC) process. For such applications, novel concepts are being developed in wet scrubbing with physical sorption, chemical sorption with solid sorbents, and separation by membranes. In one concept, a wet scrubbing technique is being investigated that uses a physical solvent process to remove CO₂ from fuel gas of an IGCC system at elevated temperature and pressure. The need to define an “ideal” solvent has led to the study of the solubility and mass transfer properties of various solvents. Pertaining to another separation technology, fabrication techniques and mechanistic studies for membranes separating CO₂ from the fuel gas produced by coal gasification are also being performed. Membranes that consist of CO₂-philic ionic liquids encapsulated into a polymeric substrate have been investigated for permeability and selectivity. Finally, processes based on dry, regenerable sorbents are additional techniques for CO₂ capture from fuel gas. An overview of these novel techniques is presented along with a research progress status of technologies related to membranes and physical solvents.     

Synthesis of narrow-distribution polycyclopentene using a ruthenium ring-opening metathesis initiator

Polycyclopentene was synthesized by ring-opening metathesis polymerization (ROMP) at room temperature, using a ruthenium-based initiator in the presence of tricyclohexylphosphine, which acts as a polymerization regulator by shifting the metal-ligand binding equilibrium. A kinetic model was developed for the monomer conversion and polymer molecular weight as a function of time, monomer concentration, and monomer-to-initiator and phosphine-to-initiator ratios, and was fit to experimental data to extract a single rate parameter. By eliminating impurities which act as chain-transfer agents, and optimizing reaction conditions to minimize secondary metathesis, polycyclopentenes of controllable molecular weight (M_n = 6-40 kg/mol) and narrow distributions (PDI ≈ 1.15) can be routinely obtained, which could be hydrogenated to perfectly linear polyethylenes. This work extends existing ROMP methods for the synthesis of precursors to narrow-distribution polyethylene, which have employed tungsten or molybdenum catalysts, to a commercially available, robust ruthenium initiator.     

Stability of phase-contrast tomography

Phase-contrast tomography (PCT) allows three-dimensional imaging of objects that display insufficient contrast for conventional absorption-based tomography. We prove that PCT is stable with respect to high-frequency noise in experimental phase-contrast data, unlike conventional tomography, which is known to be mildly unstable. We use known properties of the three-dimensional x-ray transform and transport-of-intensity equation to construct a matrix representation of the forward PCT operator. We then invert this formula to show that, under natural boundary conditions, the PCT reconstruction operator exists and leads to a unique solution. We show that the singular values s(n) of the reconstruction operator have asymptotic behavior s(n)=O(n(-3/2)), guaranteeing the mathematical stability of the reconstruction process.     

Optimal experimental design in an epidermal growth factor receptor signalling and down-regulation model

We apply the methods of optimal experimental design to a differential equation model for epidermal growth factor receptor signalling, trafficking and down-regulation. The model incorporates the role of a recently discovered protein complex made up of the E3 ubiquitin ligase, Cbl, the guanine exchange factor (GEF), Cool-1 (beta -Pix) and the Rho family G protein Cdc42. The complex has been suggested to be important in disrupting receptor down-regulation. We demonstrate that the model interactions can accurately reproduce the experimental observations, that they can be used to make predictions with accompanying uncertainties, and that we can apply ideas of optimal experimental design to suggest new experiments that reduce the uncertainty on unmeasurable components of the system.     

Determination of Critical Thickness for Epitaxial ZnTe Layers Grown by Molecular Beam Epitaxy on (211)B and (100) GaSb Substrates

Cross-section electron micrographs, cathodoluminescence images, and confocal photoluminescence (cPL) images have been acquired for ZnTe layers deposited to various thicknesses on GaSb substrates with (211)B and (100) orientations. The critical thickness of ZnTe on GaSb is predicted to range between 115 nm and 329 nm, depending on the theoretical approach chosen. For ZnTe layers grown on (211)B GaSb with thickness exceeding 150 nm, dark spots and lines are present in all images. We associate these with dislocations generated at the ZnTe/GaSb interface. The discrepancy between this thickness value and a critical thickness value (350 nm to 375 nm) obtained for the (211)B orientation in a previous study is related to the distinction between the onset of misfit dislocations and the onset of significant plastic deformation. The former requires a direct imaging technique, as strain-related measurements such as x-ray diffraction do not have the resolution to detect the effects of small numbers of dislocations. For ZnTe layers on (100) GaSb, x-ray diffraction measurements indicate an abrupt change characteristic of dislocation multiplication at a thickness value in the range from 250 nm to 275 nm. High-resolution electron micrographs of the ZnTe/GaSb interface indicate that deoxidation using atomic hydrogen produces GaSb surfaces suitable for ZnTe epitaxy. cPL images of a 1.2-μm-thick lattice-matched ZnTe_0.99Se _0.01 layer grown on a 150-nm-thick ZnTe buffer layer on a (211)B GaSb substrate yield a threading dislocation density of ～7 × 10⁴ cm^?2.