6,398 research outputs found
When Neil Smith Met Pierre Bourdieu in Nanjing, China: Bringing Cultural Capital into Rent Gap Theory
In this paper, we expand rent-gap theory in conceptual and territorial terms. Hitherto, the theory has, as Neil Smith intended, been used in an economic sense; we argue here, borrowing ideas from Pierre Bourdieu, that in the competitive environment of Chinese education, a rent gap in cultural capital is created which can later be converted into economic capital. The process we identify is triggered by the purchase of an apartment in a catchment zone, crucial to obtaining entry into a prestigious ‘key’ school in most Chinese cities. This leads to apartments changing hands for high prices despite generally being old and dilapidated. The rent gap in cultural capital occurs when parents forego potential short-term gains to capitalize on the long-term benefits of a superior education. This is contrasted here with a somewhat more conventional scenario, where property developers exploit a rent gap on suburban apartments built in the catchment of branch ‘key’ schools
Fast Predictive Simple Geodesic Regression
Deformable image registration and regression are important tasks in medical
image analysis. However, they are computationally expensive, especially when
analyzing large-scale datasets that contain thousands of images. Hence, cluster
computing is typically used, making the approaches dependent on such
computational infrastructure. Even larger computational resources are required
as study sizes increase. This limits the use of deformable image registration
and regression for clinical applications and as component algorithms for other
image analysis approaches. We therefore propose using a fast predictive
approach to perform image registrations. In particular, we employ these fast
registration predictions to approximate a simplified geodesic regression model
to capture longitudinal brain changes. The resulting method is orders of
magnitude faster than the standard optimization-based regression model and
hence facilitates large-scale analysis on a single graphics processing unit
(GPU). We evaluate our results on 3D brain magnetic resonance images (MRI) from
the ADNI datasets.Comment: 19 pages, 10 figures, 13 table
Enhanced performance of Si MOS capacitors with HfTaOxNy gate dielectric by using AlOxNy or TaOxNy interlayer
Si MOS capacitors with HfTa oxide and oxynitride as gate dielectric were fabricated. Moreover, AlOxNy or TaOxN y was used as the interlayer between HfTa oxynitride and Si substrate to improve the electrical quality of the capacitors. Experimental results showed that the HfTaOxNy capacitor with TaO xNy interlayer achieved better performance with larger capacitance and smaller leakage current than its counterpart with AlO xNy interlayer. © 2008 IEEE.published_or_final_versio
Homeostasis and function of regulatory T cells (Tregs) in vivo:lessons from TCR-transgenic Tregs
The identification of CD25 and subsequently Forkhead box protein 3 (Foxp3) as markers for regulatory T cells (Tregs) has revolutionized our ability to explore this population experimentally. In a similar vein, our understanding of antigen-specific Treg responses in vivo owes much to the fortuitous generation of T-cell receptor (TCR)-transgenic Tregs. This has permitted tracking of Tregs with a defined specificity in vivo, facilitating analysis of how encounter with cognate antigen shapes Treg homeostasis and function. Here, we review the key lessons learned from a decade of analysis of TCR-transgenic Tregs and set this in the broader context of general progress in the field. Use of TCR-transgenic Tregs has led to an appreciation that Tregs are a highly dynamic proliferative population in vivo, rather than an anergic population as they were initially portrayed. It is now clear that Treg homeostasis is positively regulated by encounter with self-antigen expressed on peripheral tissues, which is likely to be relevant to the phenomenon of peripheral repertoire reshaping that has been described for Tregs and the observation that the Treg TCR specificities vary by anatomical location. Substantial evidence has also accumulated to support the role of CD28 costimulation and interleukin-2 in Treg homeostasis. The availability of TCR-transgenic Tregs has enabled analysis of Treg populations that are sufficient or deficient in particular genes, without the comparison being confounded by repertoire alterations. This approach has yielded insights into genes required for Treg function in vivo, with particular progress being made on the role of ctla-4 in this context. As the prospect of manipulating Treg populations in the clinic becomes reality, a full appreciation of the rules governing their homeostasis will prove increasingly important
Improved electrical properties of Ge p-MOSFET with HfO 2 gate dielectric by using TaO xN y interlayer
The electrical characteristics of germanium p-metal-oxide-semiconductor (p-MOS) capacitor and p-MOS field-effect transistor (FET) with a stack gate dielectric of HfO 2TaO xN y are investigated. Experimental results show that MOS devices exhibit much lower gate leakage current than MOS devices with only HfO 2 as gate dielectric, good interface properties, good transistor characteristics, and about 1.7-fold hole-mobility enhancement as compared with conventional Si p-MOSFETs. These demonstrate that forming an ultrathin passivation layer of TaO xN y on germanium surface prior to deposition of high- k dielectrics can effectively suppress the growth of unstable GeO x, thus reducing interface states and increasing carrier mobility in the inversion channel of Ge-based transistors. © 2008 IEEE.published_or_final_versio
Co-production of hydrogen and carbon nanotubes from real-world waste plastics: Influence of catalyst composition and operational parameters
The use of Ni-Fe catalysts for the catalytic pyrolysis of real-world waste plastics to produce hydrogen and high value carbon nanotubes (CNT), and the influence of catalyst composition and support materials has been investigated. Experiments were conducted in a two stage fixed bed reactor, where plastics were pyrolysed in the first stage followed by reaction of the evolved volatiles over the catalyst in the second stage. Different catalyst temperatures (700, 800, 900 °C) and steam to plastic ratios (0, 0.3, 1, 2.6) were explored to optimize the product hydrogen and the yield of carbon nanotubes deposited on the catalyst. The results showed that the growth of carbon nanotubes and hydrogen were highly dependent on the catalyst type and the operational parameters. Fe/γ-Al₂O₃ produced the highest hydrogen yield (22.9 mmol H₂/gplastic) and carbon nanotubes yield (195 mg g−1plastic) among the monometallic catalysts, followed by Fe/α-Al₂O₃, Ni/γ-Al₂O₃, and Ni/α-Al₂O₃. The bimetallic Ni-Fe catalyst showed higher catalytic activity in relation to H₂ yield than the monometallic Ni or Fe catalysts because of the optimum interaction between metal and support. Further investigation of the influence of steam input and catalyst temperature on product yields found that the optimum simultaneous production of CNTs (287 mg g¯¹plastic) and hydrogen production (31.8 mmol H₂/gplastic) were obtained at 800°C in the absence of steam and in the presence of the bimetallic Ni-Fe/γ-Al₂O₃ catalyst
Comparative study of HfTa-based gate-dielectric Ge metal-oxide- semiconductor capacitors with and without AlON interlayer
The electrical properties and high-field reliability of HfTa-based gate-dielectric metal-oxide-semiconductor (MOS) devices with and without AlON interlayer on Ge substrate are investigated. Experimental results show that theMOS capacitor with HfTaON/AlON stack gate dielectric exhibits low interface-state/oxide-charge densities, low gate leakage, small capacitance equivalent thickness (∼1.1 nm), and high dielectric constant (∼20). All of these should be attributed to the blocking role of the ultrathin AlON interlayer against interdiffusions of Ge, Hf, and Ta and penetration of O into the Ge substrate, with the latter effectively suppressing the unintentional formation of unstable poorquality low-k GeO x and giving a superior AlON/Ge interface. Moreover, incorporation of N into both the interlayer and high-k dielectric further improves the device reliability under high-field stress through the formation of strong Nrelated bonds. © Springer-Verlag 2009.published_or_final_versionSpringer Open Choice, 01 Dec 201
β-Ga2O3 solar-blind deep-ultraviolet photodetector based on a four-terminal structure with or without Zener diodes
A four-terminal photodetector was fabricated on the (2⎯⎯⎯012¯01)-dominant β-Ga2O3 thin film which was deposited in a plasma-assisted molecular beam epitaxy system. The suitability of this film for solar-blind DUV detection was proved by its transmission spectra. Moreover, the device operating in a specific voltage-current mode can accurately detect the DUV radiation both qualitatively and quantitatively. Accordingly, a dark/photo voltage ratio of 15 was achieved, which is comparable to that of previously-reported β-Ga2O3 interdigital metal-semiconductor-metal photoconductor. More importantly, the aperture ratio of our proposed device exceeds 80%, nearly doubling that of the conventional interdigital metal-semiconductor-metal devices including photoconductor and Schottky-type photodiode, which can intensively benefit the detection efficiency. Furthermore, it was found the dark/photo voltage ratio was nearly trebled with the assistance of two Zener diodes, and further enhancement can be expected by increasing the operating current and/or adopting Zener diodes with smaller Zener voltage. Therefore, this work provides a promising alternative for solar-blind DUV detection.published_or_final_versio
Improved electrical properties of Ge metal-oxide-semiconductor capacitor with HfTa-based gate dielectric by using TaOxNy interlayer
HfTa-based oxide and oxynitride with or without Ta Ox Ny interlayer are fabricated on Ge substrate to form metal-oxide-semiconductor (MOS) capacitors. Their electrical properties and reliabilities are measured and compared. The results show that the MOS capacitor with a gate stack of HfTa-based oxynitride and thin Ta Ox Ny interlayer exhibits low interface-state/oxide-charge densities, low gate leakage, small hysteresis, small capacitance equivalent thickness (∼0.94 nm), and high dielectric constant (∼24). All these should be attributed to the blocking role of the Ta Ox Ny interlayer against penetration of O into the Ge substrate and interdiffusions of Hf, Ge, and Ta, thus effectively suppressing the formation of unstable low- k Ge Ox and giving a superior Ta Ox Ny Ge interface. Moreover, incorporation of N into both the interlayer and high- k dielectric greatly improves device reliability through the formation of strong N-related bonds. © 2008 American Institute of Physics.published_or_final_versio
SHRIMP zircon geochronology of the Emeishan Large Igneous Province (SW China): implications for double mass extinctions in Late Permian
Abstract in http://www.lpi.usra.edu/meetings/gold2001/pdf/3519.pd
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