5,665 research outputs found
Macroscale multimodal imaging reveals ancient painting production technology and the vogue in Greco-Roman Egypt.
Macroscale multimodal chemical imaging combining hyperspectral diffuse reflectance (400-2500 nm), luminescence (400-1000 nm), and X-ray fluorescence (XRF, 2 to 25 keV) data, is uniquely equipped for noninvasive characterization of heterogeneous complex systems such as paintings. Here we present the first application of multimodal chemical imaging to analyze the production technology of an 1,800-year-old painting and one of the oldest surviving encaustic ("burned in") paintings in the world. Co-registration of the data cubes from these three hyperspectral imaging modalities enabled the comparison of reflectance, luminescence, and XRF spectra at each pixel in the image for the entire painting. By comparing the molecular and elemental spectral signatures at each pixel, this fusion of the data allowed for a more thorough identification and mapping of the painting's constituent organic and inorganic materials, revealing key information on the selection of raw materials, production sequence and the fashion aesthetics and chemical arts practiced in Egypt in the second century AD
Exploring the Performance of Active Thermal Tiles for Space Applications
The Active Thermal Tiles (ATTs) experiment explores another option for managing electronic component temperatures onboard spacecraft. The ATTs are based on thermoelectric devices that can alter the thermal gradient between the bus and component. Because ATTs do not rely on fluids or moving parts, they are highly reliable devices which make them attractive for use in spacecraft. An ATT experimental ground unit was tested in a vacuum chamber under 88 different conditions over a temperature range of 280K to 310K. The power supplied to the electronic component was varied between 5W and 40W, and the current running through the ATTs was varied between 0.0A and 3.0A. Conductance and the coefficient of performance were measured, and a performance map was created. In addition, the power used by the ATTs was compared against the power used by survival heaters. Results showed the ATTs require less power to create the same temperature differential as survival heaters proving ATTs are more efficient than a traditional survival heat approach. Also, a computer simulation of the ATT was calibrated and used to compare the two control methods for the ATTs: PID or On-Off. PID control was up to two times as efficient as On-Off control. Ground tests were run to confirm the results from the simulation
A Multidimensional Approach to Understanding Gender and Health among Middle-Aged and Older Adults
Women get sicker, men die quicker, is a statement used to describe how women suffer from more chronic health conditions, greater physical limitations, and report poorer health compared to men (Crimmins, Kim, & Sole -Auro, 2011; Lochner & Cox, 2010), whereas men have a shorter life expectancy compared to women (CDC, 2013). Although biological sex differences offer some explanation for why men and women differ in health and mortality, there is much left unexplained (Miller, 2014). Gender, a psychosocial construct that reflects attitudes, feelings, and behaviors prescribed by cultural expectations for men and women (Unger, 1979) has been highlighted as an important, yet understudied construct, that can influence sex differences in health (Courtenay, 2000; Evans, Frank, Oliffe, & Gregory, 2011). The current study applied a multidimensional approach that tested how gender-typed traits (e.g., masculine and feminine traits) and behaviors (e.g., interdependence and health behaviors) related to three health outcomes (i.e., perceived health, physical functioning, and chronic health burden). The sample was comprised of 486 middle-aged and older adults (40-79 years old; Mage = 55.57; 54.5% female) recruited from Amazon\u27s Mechanical Turk Program and the community (i.e., via social media). Findings indicated that although there were no main sex differences in health outcomes, gender-typed traits were differentially associated with behaviors (e.g., social support, health-risk behaviors) that are known to impact health. For example, men and women who reported greater endorsement of masculine traits reported significantly greater health-promoting behaviors, greater social support, less interdependent problem solving, and greater health-risk behaviors. Men and women who reported greater endorsement of feminine traits reported significantly greater health-promoting behaviors, greater social support, greater interdependent problem solving, and fewer health-risk behaviors. The findings provide a new perspective for understanding how gender may influence behaviors, which in turn can lead to varying health consequences
Age and Gender Differences in Decision-Making Style Profiles
The current study examined Scott and Bruce\u27s (1995) five decision-making styles (i.e. rational, intuitive, spontaneous, dependent, and avoidant) to assess potential combinations of styles using cluster analysis. The sample comprised 1,075 members from RAND\u27s American Life Panel (56.2% female, 18-93 years, Mage = 53.49). Data was collected from a larger survey that members completed on a monthly basis. Findings yielded a three-cluster model which included: affective/experiential, dependent, and independent/self-controlled decision-making style profiles. These profiles were significantly differentiated by age and gender. Older age and being female was associated with being more likely to be in the independent/self-controlled decision-making style profile than the affective/experiential decision-making style profile. The findings provide a new perspective for examining how people approach decisions and provide support for certain aspects of decision-making process theories
Contextos da prática docente: (re)pensando o papel do contexto em intervenções com professores da educação infantil e novas abordagens para a leitura compartilhada
Although the randomized controlled trial has been regarded as the sine qua non in recent years, we argue that understanding contexts for teacher practice is a critical factor in the implementation of intervention, but has often been overlooked in educational research design. In this paper, we argue that randomized trials may not be ideal for educational contexts that are multi-faceted, complex and often part of other community-based initiatives. To make this argument, we describe a study from “the context out,” a different lens than is typical in education research. In doing so, we consider how varied contexts create both constraints and affordances for teachers to engage in an intervention. Examining how teachers engage with new curricular practices, we focus closely on five early childhood centers in high poverty neighborhoods, using mixed methods to understand both the influence of the intervention as well as the conditions that either supported or thwarted changes in practice. Our findings suggest that context plays a major role in educational practice, which has important implications for approaches to research in the future. Given this reality, we argue that an understanding of the context in which an intervention takes place must be considered in any calculation of “what works” in classrooms.Aunque los experimentos controlados aleatorios han sido considerados como condición sine qua non en los últimos años, argumentamos que la comprensión de los contextos de la práctica docente es un factor crítico en la implementación de intervenciones, pero a menudo se han pasado por alto en los diseños de investigación educativa. En este trabajo, argumentamos que los experimentos controlados aleatorios pueden no ser ideales para los contextos educativos que son de facetas múltiples, complejas y con frecuencia parte de otras iniciativas basadas en la comunidad. Para sustentar este argumento, describimos un estudio "fuera de contexto," un objetivo no típico en la investigación en educación. Tenemos en cuenta como contextos variados crean tanto restricciones como posibilidades para que docentes participen en una intervención. Examinamos cómo los docentes se comprometen con nuevas prácticas curriculares, focalizando particularmente en cinco centros para la primera infancia en barrios con altos niveles de pobreza, usando métodos mixtos para entender tanto la influencia de la intervención, así como las condiciones para favorecer o dificultar cambios en las prácticas. Nuestros hallazgos sugieren que el contexto juega un papel importante en la práctica educativa, lo que tiene importantes implicaciones para pensar investigaciones futuras. Dados nuestros resultados argumentamos que la comprensión del contexto en el que se lleva a cabo una intervención debe ser considerada en el cálculo de "lo que funciona" en las aulas.Apesar de experimentos controlados randomizados foram considerados como condição sine qua non, nos últimos anos, argumentamos que a compreensão dos contextos de prática de ensino é um fator crítico para a implementação de intervenções, mas têm sido muitas vezes negligenciado em projetos de investigação educacional. Neste artigo, argumentamos que os experimentos controlados randomizados podem não ser ideal para contextos educativos que são múltiplos, complexos e muitas vezes parte de outras iniciativas facetas de base comunitária. Para sustentar esse argumento, descrevemos um estudo "fora de contexto", um objetivo que não é típica na pesquisa em educação. Consideramos como variados contextos criar ambos os constrangimentos e oportunidades para os professores a participar de uma intervenção. Examinamos como os professores se envolver com novas práticas curriculares, com particular incidência em cinco centros para a primeira infância nos bairros com altos níveis de pobreza, uso de métodos mistos para entender tanto a influência da intervenção, bem como as condições para favorecer ou dificultar mudanças as praticas. Nossos resultados sugerem que o contexto desempenha um papel importante na prática educativa, que tem implicações importantes para o futuro pensamento pesquisa. Dadas nossas descobertas sustentamos que a compreensão do contexto em que é realizada uma intervenção deve ser considerado no cálculo do "o que funciona" em sala de aula
Particle Impact Analysis of Bulk Powder During Pneumatic Conveyance
Fragmentation of powders during transportation is a common problem for manufacturers of food and pharmaceutical products. We illustrate that the primary cause of breakage is due to inter-particle collisions, rather than particle-wall impacts, and provide a statistical mechanics model giving the number of collisions resulting in fragmentation
Who is buying urban condominiums? : a tale of four cities
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Architecture, 2005.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references.This thesis is an analysis of the current trend in urban condominium and loft sales in the United States. It focuses specifically on the question of whom, demographically speaking, is buying the incredible influx of new urban residential products that has come onto the market since 2000. There is only anecdotal evidence gathered to date, where some claim that it is the empty-nesters abandoning the suburbs for the convenience of city life. However, there has not been the corresponding drop in suburban population levels or house sale levels to corroborate that hypothesis. Other market participants claim that the sales are primarily to investors, who are either renting or riding appreciation expectations to resell. If that is true, then there are considerable market implications for the future. Others project that it is an urban pied-a-terre trend; however the 2000 census only identifies 3% of the whole housing stock as seasonal, recreational, or second homes. This thesis pools and analyzes recent historical data in four urban downtowns: Atlanta, Boston, Chicago, and San Diego to determine what is happening in each city and to try to discover a national trend. It utilizes raw mortgage origination data, assessor's data, and surveys and interviews with developers and brokers in each of the four designated cities.(cont.) In addition to demographic profiles of buyers, this study determines whether these are second homes, speculative purchases, or complete relocations from outside the city. Ultimately, what can be concluded from this analysis is that a much larger segment of demand for urban condos in Atlanta, Boston, Chicago and San Diego consists of second home purchasers and investors than are counted in the 2000 Census. Surveys of 7849 units indicate 66% owner occupancy, 22% second home purchase plus investors with no plan to rent and finally another 12% investors who rent out their units. Trends are similar across markets, although the Atlanta market is driven by younger buyers and San Diego has the lowest percentage of owner occupants, indicating the most speculative buying.by Robert M. DeLaney and Linda K. Pizzuti.S.M
Accounting for the foreground contribution to the dust emission towards Kepler's supernova remnant
‘The definitive version is available at www3.interscience.wiley.com '. Copyright Royal Astronomical Society. DOI: 10.1111/j.1365-2966.2009.15061.xWhether or not supernovae contribute significantly to the overall dust budget is a controversial subject. Submillimetre (sub-mm) observations, sensitive to cold dust, have shown an excess at 450 and 850 μm in young remnants Cassiopeia A (Cas A) and Kepler. Some of the sub-mm emission from Cas A has been shown to be contaminated by unrelated material along the line of sight. In this paper, we explore the emission from material towards Kepler using sub-mm continuum imaging and spectroscopic observations of atomic and molecular gas, via H i, 12CO(J= 2–1) and 13CO(J= 2–1). We detect weak CO emission (peak T*A = 0.2–1 K, 1–2 km s−1 full width at half-maximum) from diffuse, optically thin gas at the locations of some of the sub-mm clumps. The contribution to the sub-mm emission from foreground molecular and atomic clouds is negligible. The revised dust mass for Kepler's remnant is 0.1–1.2 M⊙ , about half of the quoted values in the original study by Morgan et al., but still sufficient to explain the origin of dust at high redshifts.Peer reviewe
Binding energies and electronic structures of adsorbed titanium chains on carbon nanotubes
We have studied the binding energies and electronic structures of metal (Ti,
Al, Au) chains adsorbed on single-wall carbon nanotubes (SWNT) using first
principles methods. Our calculations have shown that titanium is much more
favored energetically over gold and aluminum to form a continuous chain on a
variety of SWNTs. The interaction between titanium and carbon nanotube
significantly modifies the electronic structures around Fermi energy for both
zigzag and armchair tubes. The delocalized 3d electrons from the titanium chain
generate additional states in the band gap regions of the semiconducting tubes,
transforming them into metals.Comment: 4 pages, 3 figure
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