bluuebunny/crossref_metadata_2025 huggingface dataset:
Dry Etching of Nanosized Si2Sb2Te5 Patterns using TiN Hard Mask for High Density Phase-change Memory
Authors: Feng Gaoming , Song Zhitang , Liu Bo , Feng Songlin , Chen Baoming
Published: July 2009

Compared to Dram and flash memory, CRAM (chalcogenide random access memory), which is a non-volatile memory using a reversible phase change between amorphous and crystalline state, has many advantages such as high speed, high sensing margin, low operating voltage, and is being pursed as a next generation memory. Being able to pattern and etch chalcogenide in nanoscale is essential for the integration of CRAM. We investigated the etching characteristics of Si2Sb2Te5 in a CHF3/O2 gas mixture using a reactive ion etching system. The nanosized Si2Sb2Te5 patterns were defined by electron-beam lithography, and a hard mask TiN was chosen for Si2Sb2Te5 etching. Using these optimized etching parameters and patterning conditions, 500nm Si2Sb2Te5 square could be successfully obtained with good profiles and uniformity.
Ultra Thin Oxide by Chemical Vapour Oxidation of Si
Authors: Kailath Binsu J. , DasGupta Amitava , DasGupta Nandita
Published: July 2009

Continued MOSFET scaling necessitates the use of high-k materials which in turn need an ultra thin (<0.6nm) SiO2 buffer layer between the high-k material and the silicon substrate, to obtain a better interface. In this paper a novel technique to grow extremely thin (as low as 0.6 nm) oxide by nitric acid vapour at low temperature and effect of ac anodization on these oxides are discussed. The effective oxide thickness obtained for these chemical oxides has been found to be ranging from 0.6 nm to 1.5 nm. C-V, I-V and reliability characteristics have been studied. The oxide thickness increases with increase in molarity of the HNO3. At an electric field of 10 MV/cm, the leakage current density for the thinnest oxide is 0.6 A/cm2. These values are better than those for oxides grown in HNO3 solution. Anodization improved the quality of the chemical vapour oxides further.
Effect of Ge2Sb2Te5 Material Properties on its CMP Process
Authors: Zhong Min , Song Zhitang , Liu Bo , Feng Songlin , Zhang Fuxiong , Xiang Yanghui
Published: July 2009

Effect of Ge2Sb2Te5 (GST) material properties (different phase states) on its chemical mechanical polishing (CMP) process is studied. Amorphous, crystalline state (200°and 250° annealing) GST film on 8-inch oxide wafers are polished in the same polish condition (mechanical parameters and slurry). CMP result shows that material removal rate (MRR) of crystalline GST is much faster than MRR of amorphous GST. Besides, MRR of crystalline GST reduces while GST annealing temperature is increased. According to the previous result, GST material phase state and GST grain size effect on GST CMP process are discussed from chemical reaction and mechanical abrasion aspects.
Atomic Vapor Deposition of TiN with Diluted Tetrakis (diethylamido) Titanium (TDEAT) for Phase Change Memory
Authors: Wang Liangyong , Liu Bo , Song Zhitang , Feng Songlin , Zhou Zhen , Xiang Yanghui , Zhang Fuxiong
Published: July 2009

We develop a 200mm Titanium Nitride (TiN) atomic vapor deposition (AVD) process for phase change memory (PCM). Diluted TDEAT is used for the deposition. By optimum the AVD parameters, we successfully develop the TiN process with accurately controllable deposition rate, good surface, stable resistivity and good repeatability. This process can be efficiently applied to PCM as the electrodes and electrode contacts.
Design of poly-Si TFT Shift Register and Latch Circuit by PMOS Process
Authors: Sun Pengfei , Wu Chunya , Meng Zhiguo , Yao Ying , Zhao Liqing , Xiong Shaozhen
Published: July 2009

The design of the PMOS dynamic shift register is proposed. This circuit had no static power consumption when generating the scan pulse output. The further research on the data driver circuit is also presented. Using PMOS dynamic shift register we had fabricated, we designed a digital signal latch unit based on PMOS TFT technology. The data signal could be sampled and latched serially through the combination of shift register and latch unit. Furthermore, we present a novel 2-phase clock shift register. It was composed of a dynamic signal transmitting part and a static signal holding part. Since the adoption of static holding circuit and the effect of bootstrapping, there is no capacitance in the schematic, which leads to a more compact and stable layout. The simulation result from Smart-Spice of Silvaco EDA software will be discussed.
Simulation of SET process in Phase-Change Random Access Memory by Three-Dimension Finite Element Modeling
Authors: Gong Yuefeng , Song Zhitang , Ling Yun , Liu Bo , Liu Yan , Feng Songlin
Published: July 2009

A three-dimension finite element model for phase change random access memory (PCRAM) is established to simulate electric, thermal and phase state distribution during SET operation. The SET behaviors of the heater addition structure (HS) and the ring-type contact in bottom electrode (RIB) structure are compared with each other. The simulation results indicate that the small BEC is benefit for heat efficiency and reliability of ratio between high resistance and low resistance during SET operation in HS cell, and the bottom electrode contactor (BEC) size Fx=80nm is good choice for RIB cell combined with the RESET operation. Also shown is that the appropriate SET on-voltage pulse time is 100ns for the low power consumption and fast operation.
Three-dimensional Finite Element Analysis of Phase Change Memory Cell with Thin TiO2 Stop Layer used for Forming Deep Sub-micro Electrode
Authors: Liu Yan , Song Zhitang , Ling Yun , Feng Songlin
Published: July 2009

Thin TiO2 layer inserted in phase change memory (PCM) cell to form Deep sub-micro Bottom Electrode (DBE) was interposed and its electrical-thermal characteristics were investigated with finite element analysis. Compare with other dielectric material, TiO2 with good heat stability and low heat conductivity is suitable for preventing heat diffusion from phase change region. Besides, TiO2 layer as stop layer during Chemical Mechanical Planarization (CMP) can effectively control the height of deep sub-micro electrode. Additionally, there exits the appropriate height of DBE (200nm) to contribute more heat during RESET operation. Compared with the conventional cell (SiN layer), the RESET threshold current of the DBE cell is reduced from 1.8mA to 1.2mA. It is illustrated in simulation results that the ratio of amorphous resistance and crystalline resistance will be larger in RESET operation when TiO2 film is 10nm approximately. Therefore, not only TiO2 film is stop layer during sub-micro electrode fabrication, but also is it benefiting for writing current reduction.
Lateral Porous Alumina Templates for Planar Organisation of Carbon Nanotubes and Semiconductor Nanowires
Authors: Pribat Didier , Gowtham Manoharan , Cojocaru Costel-Sorin , Kim B. S.
Published: July 2009

We present some of our first experiments on the controlled growth of silicon nanowires and carbon nanotubes in lateral porous alumina templates synthesized by anodic oxidation of Al thin films. Under adapted chemical vapor deposition growth conditions, and using the vapor-solid-liquid mechanism, the pores of the lateral membranes can be partially filled with silicon nanowires or carbon nanotubes, yielding a composite thin film of parallel-organized nano-objects. Such composite thin films can be further tailored and shaped by classical microelectronic-type tools and processes, in order to fabricate electronic devices.
Applying Closing Phase‐Angle Control Technique in Bounce Reduction of AC Permanent Magnet Contactor
Authors: Chi Chieh-Tsung
Published: July 2009

A new low‐cost electronic control circuit actuator is proposed for minimizing the bouncing times of an AC permanent magnet (PM) contactor after two contacts closing. The proposed new actuator overcomes the bouncing problem of an uncontrollable restrictions imposed by previously conventional AC electromagnetic (EM) contactor based on the minimization of kinetic energy prior to two contacts impact. By choosing the closing phase angle of coil voltage on purpose, the bouncing problems of the movable contact during the closing process are then overcome. The using life of contacts is then prolonged and their operating reliability is improved as well. In order to validate the feasibility and effectiveness of the proposed method here, several simulation and experimental procedures were performed on a prototype of AC PM contactor in the laboratory. Testing results actually showed that bouncing problem of contactor′s contacts during the closing process was to be controlled by using the proposed technology.
Bias in Minimum Temperature Introduced by a Redefinition of the Climatological Day at the Canadian Synoptic Stations
Authors: Vincent Lucie A. , Milewska Ewa J. , Hopkinson Ron , Malone Leslie
Published: July 2009

On 1 July 1961, the climatological day was redefined to end at 0600 UTC (coordinated universal time) at all synoptic (airport) stations in Canada. Prior to that, the climatological day ended at 1200 UTC for maximum temperature and 0000 UTC for minimum temperature. This study shows that the redefinition of the climatological day in 1961 has created a cold bias in the annual and seasonal means of daily minimum temperatures across the country while the means of daily maximum temperatures were not affected. Hourly temperatures taken at 121 stations for 1953–2007 are used to determine the magnitude of the bias and its spatial variation. It was found that the bias is more pronounced in the eastern regions; its annual mean varies from −0.2° in the west to −0.8°C in the east. Not all days are affected by this change in observing time, and the annual percentage of affected days ranges from 15% for locations in the west to 38% for locations in the east. An approach based on hourly values is proposed for adjusting the affected daily minimum temperatures over 1961–2007. The adjustment on any individual day varies from 0.5° to 12.5°C. The impact of the adjustment is assessed by examining the trends in the annual mean of the daily minimum temperatures for 1950–2007. Overall, with the adjustment, the trends are becoming either more positive or are reversing from negative to positive, and they have changed by as much as 1°C in numerous locations in the eastern regions.
A Physically Based Daily Hydrometeorological Model for Complex Mountain Terrain
Authors: MacDonald Ryan J. , Byrne James M. , Kienzle Stefan W.
Published: July 2009

This paper describes the continued development of the physically based hydrometeorological model Generate Earth Systems Science input (GENESYS) and its application in simulating snowpack in the St. Mary (STM) River watershed, Montana. GENESYS is designed to operate a high spatial and temporal resolution over complex mountainous terrain. The intent of this paper is to assess the performance of the model in simulating daily snowpack and the spatial extent of snow cover over the St. Mary River watershed. A new precipitation estimation method that uses snowpack telemetry (SNOTEL) and snow survey data is presented and compared with two other methods, including Parameter-elevation Regressions on Independent Slopes Model (PRISM) precipitation data. A method for determining daily temperature lapse rates from NCEP reanalysis data is also presented and the effect of temperature lapse rate on snowpack simulations is determined. Simulated daily snowpack values compare well with observed values at the Many Glacier SNOTEL site, with varying degrees of accuracy, dependent on the method used to estimate precipitation. The spatial snow cover extent compares well with Moderate Resolution Imaging Spectroradiometer (MODIS) snow cover products for three dates selected to represent snow accumulation and ablation periods.
Soil Surface Energy and Water Budgets during a Monsoon Season in Korea
Authors: Cassardo Claudio , Park Seon Ki , Malla Thakuri Bindu , Priolo Daniela , Zhang Ying
Published: July 2009

In this study, attention has been focused on the climatology of some variables linked to the turbulent exchanges of heat and water vapor in the surface layer during a summer monsoon in Korea. In particular, the turbulent fluxes of sensible and latent heat, the hydrologic budget, and the soil temperatures and moistures have been analyzed. At large scale, because the measurements of those data are not only fragmentary and exiguously available but also infeasible for the execution of climatologic analyses, the outputs of a land surface scheme have been used as surrogate of observations to analyze surface layer processes [this idea is based on the methodology Climatology of Parameters at the Surface (CLIPS)] in the Korean monsoonal climate. Analyses have been made for the summer of 2005. As a land surface scheme, the land surface process model (LSPM) developed at the University of Torino, Italy, has been employed, along with the data collected from 635 Korean meteorological stations. The LSPM predictions showed good agreement with selected observations of soil temperature. Major results show that, during the rainfall season, soil moisture in the first tenths of centimeters frequently exceeds the field capacity, whereas most of the rainfall is “lost” as surface runoff. Evapotranspiration is the dominant component of the energy budget, sometimes even exceeding net radiation, especially during the short periods between the precipitation events; in these periods, daily mean soil temperatures are about 28°C or even more. The Gyeonggi-do region, the metropolitan area surrounding Seoul, shows some particularities when compared with the neighboring regions: solar radiation and precipitations are lower, causing high values of sensible heat flux and soil temperatures, and lower values of latent heat flux and soil moistures.
Stochastic Precipitation Generation Based on a Multivariate Autoregression Model
Authors: Makhnin Oleg V. , McAllister Devon L.
Published: July 2009

The problem of stochastic precipitation generation has long been of interest. A good generator should produce time series with statistical properties to match those of the real precipitation. Here, a multivariate autoregression model designed to capture the covariance and lag-1 cross-covariance structure of the precipitation measurements is presented. A truncated and power-transformed normal distribution is used to simultaneously model both occurrences and amounts of daily precipitation. The methodology is illustrated using daily rain gauge datasets for three areas in the continental United States.
Hydroclimatic Response of Watersheds to Urban Intensity: An Observational and Modeling-Based Analysis for the White River Basin, Indiana
Authors: Yang Guoxiang , Bowling Laura C. , Cherkauer Keith A. , Pijanowski Bryan C. , Niyogi Dev
Published: July 2009

Impervious surface area (ISA) has different surface characteristics from the natural land cover and has great influence on watershed hydrology. To assess the urbanization effects on streamflow regimes, the authors analyzed the U.S. Geological Survey (USGS) streamflow data of 16 small watersheds in the White River [Indiana (IN)] basin. Correlation between hydrologic metrics (flow distribution, daily variation in streamflow, and frequency of high-flow events) and ISA was investigated by employing the nonparametric Mann–Kendall method. Results derived from the 16 watersheds show that urban intensity has a significant effect on all three hydrologic metrics. The Variable Infiltration Capacity (VIC) model was modified to represent ISA in urbanized basins using a bulk parameterization approach. The model was then applied to the White River basin to investigate the potential ability to simulate the water and energy cycle response to urbanization. Correlation analysis for individual VIC grid cells indicates that the VIC urban model was able to reproduce the slope magnitude and mean value of the USGS streamflow metrics. The urban model also reproduced the urban heat island (UHI) seen in the Moderate Resolution Imaging Spectroradiometer (MODIS) land surface temperature products, especially for the grids encompassing the city of Indianapolis, IN. The difference of the hydrologic metrics obtained from the VIC model with and without urban representation indicates that the streamflow regime in the White River has been modified because of urban development. The observed data, together with model analysis, suggested that 3%–5% ISA in a watershed is the detectable threshold, beyond which urbanization effects start to have a statistically significant influence on streamflow regime.
Linear Fluctuation Growth during Frontogenesis
Authors: McWilliams James C. , Molemaker M. J. , Olafsdottir E. I.
Published: July 2009

Near-surface, two-dimensional (2D) baroclinic frontogenesis induced by a barotropic deformation flow enhances the growth of three-dimensional (3D) fluctuations that occur on an ever smaller scale as the front progressively sharpens. The 3D fluctuation growth rate further increases with a larger deformation rate. The fluctuations grow by a combination of baroclinic and barotropic energy conversions from the 2D frontal flow, with the former dominating for most of the situations examined, ranging from small to 𝒪(1) values of the Rossby and Froude numbers and nondimensional deformation rate. Averaged 3D fluctuation buoyancy fluxes resist the 2D frontogenesis by a frontolytic tendency. They also augment the buoyancy restratification and potential-to-kinetic energy conversion tendencies of the 2D frontogenesis itself, and the 2D frontogenetic and 3D eddy-induced secondary circulations are mostly reinforcing (unlike in turbulent baroclinic jets). This shows that frontal instability coexists with, and potentially may even overcome, active frontogenesis; this conclusion is contrary to some previous studies. Frontal instability thus can augment frontogenesis in accomplishing a forward cascade of energy from oceanic mesoscale eddies into the submesoscale regime en route to finescale dissipation.
Enhancement of Mesoscale Eddy Stirring at Steering Levels in the Southern Ocean
Authors: Abernathey Ryan , Marshall John , Mazloff Matt , Shuckburgh Emily
Published: July 2009

Meridional cross sections of effective diffusivity in the Southern Ocean are presented and discussed. The effective diffusivity, Keff, characterizes the rate at which mesoscale eddies stir properties on interior isopycnal surfaces and laterally at the sea surface. The distributions are obtained by monitoring the rate at which eddies stir an idealized tracer whose initial distribution varies monotonically across the Antarctic Circumpolar Current (ACC). In the absence of observed maps of eddying currents in the interior ocean, the advecting velocity field is taken from an eddy-permitting state estimate of the Southern Ocean (SOSE). A three-dimensional advection–diffusion equation is solved and the diffusivity diagnosed by applying the Nakamura technique on both horizontal and isopycnal surfaces. The resulting meridional sections of Keff reveal intensified isopycnal eddy stirring (reaching values of ∼2000 m2 s−1) in a layer deep beneath the ACC but rising toward the surface on the equatorward flank. Lower effective diffusivity values (∼500 m2 s−1) are found near the surface where the mean flow of the ACC is strongest. It is argued that Keff is enhanced in the vicinity of the steering level of baroclinic waves, which is deep along the axis of the ACC but shallows on the equatorial flank. Values of Keff are also found to be spatially correlated with gradients of potential vorticity on isopycnal surfaces and are large where those gradients are weak and vice versa, as expected from simple dynamical arguments. Finally, implications of the spatial distributions of Keff for the dynamics of the ACC and its overturning circulation are discussed.
An Observing System Simulation Experiment (OSSE) for Aerosol Optical Depth from Satellites
Authors: Timmermans Renske M. A. , Schaap Martijn , Builtjes Peter , Elbern Hendrik , Siddans Richard , Tjemkes Stephen , Vautard Robert
Published: July 2009

Monitoring aerosols over wide areas is a scientific challenge with important applications for human health and the understanding of climate. Aerosol optical depth (AOD) measurements from satellites can improve the highly needed analyzed and forecasted distributions of ground-level aerosols in combination with models and ground-based measurements. To assess the benefit of future satellite AOD measurements, an observing system simulation experiment (OSSE) is developed. In this pilot study, the OSSE is applied to total AOD measurements from a flexible combined imager (FCI) proposed to fly on a geostationary satellite. OSSEs are widely used in the meteorological research community, but their use for air quality applications and specifically for aerosols is new. In this paper, the functionality and potential of the developed OSSE for evaluation of aerosol data from future satellite missions are demonstrated. The results show a positive impact of adding AOD observations next to in situ observations for the analysis of PM2.5 (particles smaller than 2.5 μm in median diameter) distributions. However, the development of an OSSE for aerosols presents a number of further challenges, as discussed in this paper, which prohibits a detailed quantitative analysis of the results of this pilot study.
Microwave Radiometer Calibration on Decadal Time Scales Using On-Earth Brightness Temperature References: Application to the TOPEX Microwave Radiometer
Authors: Brown Shannon , Desai Shailen , Keihm Stephen , Lu Wenwen
Published: July 2009

A method is described to calibrate a satellite microwave radiometer operating near 18–37 GHz on decadal time scales for the purposes of climate studies. The method uses stable on-earth brightness temperature references over the full dynamic range of on-earth brightness temperatures to stabilize the radiometer calibration and is applied to the Ocean Topography Experiment (TOPEX) Microwave Radiometer (TMR). These references are a vicarious cold reference, which is a statistical lower bound on ocean surface brightness temperature, and heavily vegetated, pseudoblackbody regions in the Amazon rain forest. The sensitivity of the on-earth references to climate variability is assessed. No significant climate sensitivity is found in the cold reference, as it is not sensitive to a climate minimum (e.g., coldest sea surface temperature or driest atmosphere) but arises because of a minimum in the sea surface radio brightness that occurs in the middle of the climatic distribution of sea surface temperatures (SSTs). The hot reference is observed to have a small climate dependency, which is most evident during the 1997/98 El Niño event. A time-dependent model for the hot reference region is constructed using meteorological fields from the National Centers for Environmental Prediction–National Center for Atmospheric Research (NCEP–NCAR) reanalysis product. This model is shown to accurately account for the small climate variations in this reference. In addition to the long-term stabilization of the brightness temperatures, an improvement to the TMR antenna pattern correction is described that removes residual geographically correlated errors, in particular errors correlated with distance to land or sea ice. The recalibrated TMR climate data record is cross-validated with the climate data record produced from the Special Sensor Microwave Imager (SSM/I). It is shown that the intersensor drift is small, providing realistic error bars for the climate trends generated from the instrument pair, as well as validating both the methodology described in this paper and the SSM/I climate data record.
A Portable Airborne Scanning Lidar System for Ocean and Coastal Applications
Authors: Reineman Benjamin D. , Lenain Luc , Castel David , Melville W. Kendall
Published: July 2009

A portable compact airborne scanning lidar system based on the Riegl LMS-Q240i has been developed and its functionality demonstrated for oceanographic and coastal measurements. Differential GPS (DGPS) and an inertial navigation system are synchronized with the lidar, resulting in vertical rms errors of less than 9 cm. Surveys with this airborne system are compared with ground-based DGPS surveys of fixed targets. Measurements of the southern California coastline and nearshore surface wave fields from 17 research flights between August 2007 and December 2008 are analyzed and discussed. The October 2007 landslide on Mt. Soledad in La Jolla, California, was documented by two of the flights. The topography, lagoon, reef, and surrounding wave field of Lady Elliot Island in Australia’s Great Barrier Reef were measured with the airborne scanning lidar system on eight research flights in April 2008. Applications of the system, including coastal topographic surveys, wave measurements, ship wake studies, and coral reef research, are presented and discussed.
Objective Classification of Tornadic and Nontornadic Severe Weather Outbreaks
Authors: Mercer Andrew E. , Shafer Chad M. , Doswell Charles A. , Leslie Lance M. , Richman Michael B.
Published: July 2009

Tornadoes often strike as isolated events, but many occur as part of a major outbreak of tornadoes. Nontornadic outbreaks of severe convective storms are more common across the United States but pose different threats than do those associated with a tornado outbreak. The main goal of this work is to distinguish between significant instances of these outbreak types objectively by using statistical modeling techniques on numerical weather prediction output initialized with synoptic-scale data. The synoptic-scale structure contains information that can be utilized to discriminate between the two types of severe weather outbreaks through statistical methods. The Weather Research and Forecast model (WRF) is initialized with synoptic-scale input data (the NCEP–NCAR reanalysis dataset) on a set of 50 significant tornado outbreaks and 50 nontornadic severe weather outbreaks. Output from the WRF at 18-km grid spacing is used in the objective classification. Individual severe weather parameters forecast by the model near the time of the outbreak are analyzed from simulations initialized at 24, 48, and 72 h prior to the outbreak. An initial candidate set of 15 variables expected to be related to severe storms is reduced to a set of 6 or 7, depending on lead time, that possess the greatest classification capability through permutation testing. These variables serve as inputs into two statistical methods, support vector machines and logistic regression, to classify outbreak type. Each technique is assessed based on bootstrap confidence limits of contingency statistics. An additional backward selection of the reduced variable set is conducted to determine which variable combination provides the optimal contingency statistics. Results for the contingency statistics regarding the verification of discrimination capability are best at 24 h; at 48 h, modest degradation is present. By 72 h, the contingency statistics decline by up to 15%. Overall, results are encouraging, with probability of detection values often exceeding 0.8 and Heidke skill scores in excess of 0.7 at 24-h lead time.
Rainfall Characteristics and Convective Properties of Mei-Yu Precipitation Systems over South China, Taiwan, and the South China Sea. Part I: TRMM Observations
Authors: Xu Weixin , Zipser Edward J. , Liu Chuntao
Published: July 2009

Rainfall characteristics and mesoscale properties of precipitation systems in mei-yu seasons over South China, Taiwan, and the South China Sea (SCS) during 1998–2007 are investigated in this study. Mei-yu rainbands are defined using the Tropical Rainfall Measuring Mission 3B42 rainfall product and then applied to divide the mei-yu season into the mei-yu and break periods. In the 10-yr “climatology,” on average, the mei-yu rainbands have a lifetime of 4–5 days and most frequently occur near the South China coast. During the mei-yu periods, rainfall maxima are found over the Pearl River Delta, the foothills of the Yun-Gui Plateau, and Wuyi Mountain, with the first two maxima corresponding to especially heavy rainfall. Intraseasonal variations on the convective structures, especially over land, are distinct among the mei-yu, break, pre-mei-yu, and post-mei-yu, based on analysis of convection intensity proxies and vertical radar reflectivity profiles of precipitation features. Lightning flash rates are consistent with the convective structure. The most frequent lightning over South China and Taiwan is in the pre-mei-yu and the least is during the mei-yu, which suggests different microphysical structures. Therefore, the discrimination of intraseasonal transitions on convective vertical structures may have important implications to the problems of cumulus parameterization, model validation, rainfall estimation, and latent heat retrievals. Intraseasonal variations of convective structures over the SCS are less evident than those over land. Storms over the SCS during the mei-yu are slightly convectively stronger than those in the break. Oceanic features with strong ice scattering have much lower lightning flash rates than their counterparts over land.
Neutral Saturated Lapse Rate: An Experimental Check from CALJET-1998 and PACJET-2001
Authors: Richiardone Renzo , Manfrin Massimiliano
Published: July 2009

The lapse rates of high-resolution temperature profiles during nearly neutral, saturated conditions are compared with the saturated adiabatic lapse rate and with that proposed by Richiardone and Giusti. A good agreement between the latter and the mean value of the observed lapse rate is found, whereas the saturated adiabatic lapse rate differs significantly, confirming experimentally that it is not completely correct to assess the moist neutrality from a comparison with the saturated adiabatic lapse rate. The lapse-rate distribution supports the hypothesis that the lapse-rate statistics is a local collection of saturated adiabatic lapse rates in a background normal distribution centered around the neutrality.
Tropical Cyclone Convection and Intensity Analysis Using Differenced Infrared and Water Vapor Imagery
Authors: Olander Timothy L. , Velden Christopher S.
Published: July 2009

A technique to identify and quantify intense convection in tropical cyclones (TCs) using bispectral, geostationary satellite imagery is explored. This technique involves differencing the water vapor (WV) and infrared window (IRW) channel brightness temperature values, which are available on all current operational geostationary weather satellites. Both the derived IRW minus WV (IRWV) imagery and the raw data values can be used in a variety of methods to provide TC forecasters with important information about current and future intensity trends, a component within the operational TC forecasting arena that has shown little improvement during the past few decades.

In this paper several possible uses for this bispectral technique, both qualitative and quantitative, are explored and outlined. Qualitative monitoring of intense convection can be used as a proxy for passive microwave (MW) imager data obtained from polar-orbiting satellite platforms when not available. In addition, the derived imagery may aid in the TC storm center identification process, both manually and objectively, especially in difficult situations where the IRW imagery alone cannot be used such as when the storm circulation center and/or eye features are obscured by a cirrus canopy. Quantitative methods discussed involve the predictive quality of the IRWV data in terms of TC intensity changes, primarily during TC intensification. Strong correlations exist between storm intensity changes and IRWV values at varying 6-h forecast interval periods, peaking between the 12- and 24-h time periods. Implications for the use of the IRWV data on such objective satellite intensity estimate algorithms as the University of Wisconsin—Madison (UW) Cooperative Institute for Meteorological Satellite Studies (CIMSS) advanced Dvorak technique (ADT) are also discussed.
Parental input and connective acquisition: A growth curve analysis
Authors: van Veen Rosie , Evers-Vermeul Jacqueline , Sanders Ted , van den Bergh Huub
Published: July 2009

In this study, the influence of parental input on the acquisition of discourse connectives was investigated. Three factors were hypothesized to play a role in contributing to the course of language acquisition: first, an increase in age, and hence, an increase in conceptual abilities; second, short-term frequency effects (effects of parental input in the space of one recording); and third, long-term frequency effects (effects of the cumulative parental input over a longer period of time). The authors developed a growth curve analysis and used this to analyze data from a dense longitudinal corpus of a German boy aged 1;11.12—2;11.27. Results show that each factor has a significant effect on the acquisition of the German connectives aber `but,' damit `so that,' und `and,' weil `because,' and wenn `when' and should always be taken into account when studying connective acquisition. Furthermore, growth curve analysis promises to be an innovative tool to study factors influencing the course of language acquisition.
Three-dimensional Nickel(II) Heptacyanomolybdate(III)-based Magnet
Authors: Tomono Keisuke , Tsunobuchi Yoshihide , Nakabayashi Koji , Kosaka Wataru , Matsuda Tomoyuki , Ohkoshi Shin-ichi
Published: July 2009

Herein we prepared a three-dimensional nickel heptacyanomolybdate-based magnet, K0.6NiII1.7[MoIII(CN)7]·5.5H2O·0.5CH3OH. This compound exhibited magnetic ordering with a Curie temperature of 28 K due to ferromagnetic coupling between magnetic spins on NiII (S=1) and MoIII (S=1⁄2).
Radiographic texture analysis of densitometric calcaneal images: Relationship to clinical characteristics and to bone fragility
Authors: Vokes Tamara , Lauderdale Diane , Ma Siu-Ling , Chinander Mike , Childs Keona , Giger Maryellen
Published: July 2009

Osteoporotic fractures are related not only to bone mineral density (BMD) but also to bone structure or microarchitecture, which is not assessed routinely with currently available methods. We have developed radiographic texture analysis (RTA) for calcaneal images from a peripheral densitometer as an easy, noninvasive method for assessing bone structure. We conducted a cross-sectional study of the relationship between RTA and prevalent vertebral fractures (n = 148) among 900 subjects (ages 19 to 99 years, 94 males) referred for bone densitometry as part of their routine medical care. RTA features were derived from Fourier-based image analysis of the radiographic texture pattern (including root mean square, first moment, and power spectral analyses). RTA features were associated with age, weight, gender, and race, as well as glucocorticoid use. When controlling for clinical risk factors and BMD (or a summary measure calculated using FRAX algorithms), RTA features were significantly different for subjects with and without prevalent vertebral fractures [adjusted odds ratio (OR) = 1.5 per 1 standard deviation (SD) decrease in RTA feature beta, 95% confidence interval (CI) 1.2–1.8, p = .001]. Gender and use of pharmacologic therapy for osteoporosis did not significantly affect this association, suggesting that RTA can be applied to a wide range of densitometry patients. We conclude that RTA obtained using a portable instrument has a potential as a noninvasive method to enhance identification of patients at increased risk of osteoporotic fractures. Copyright © 2010 American Society for Bone and Mineral Research
The orphan nuclear receptor SHP is a positive regulator of osteoblastic bone formation
Authors: Jeong Byung-Chul , Lee Yong-Soo , Bae In-Ho , Lee Chul-Ho , Shin Hong-In , Ha Hyun Jung , Franceschi Renny T , Choi Hueng-Sik , Koh Jeong-Tae
Published: July 2009

The orphan nuclear receptor small heterodimer partner (SHP; NR0B2) interacts with a diverse array of transcription factors and regulates a variety of cellular events such as cell proliferation, differentiation, and metabolism. However, the role of SHP in bone formation has not yet been elucidated. SHP expression is significantly increased during osteoblast differentiation, and its expression is partially regulated by bone morphogenetic protein 2 (BMP-2), which plays an important role in bone formation. In our study, inhibition of SHP expression significantly repressed BMP-2-induced osteoblast differentiation and ectopic bone formation. In accordance with these in vitro and in vivo results, osteoblast differentiation in SHP−/− mice primary osteoblasts was significantly repressed, and the mice showed decreased bone mass resulting from decreased numbers of osteoblasts. Finally, SHP physically interacts and forms a complex with runt-related transcription factor 2 (Runx2) on the osteocalcin gene promoter, and overexpression of SHP increased Runx2 transactivity via competition with histone deacetylase 4 (HDAC4), an enzyme that inhibits DNA binding of Runx2 to its target genes. Taken together, these results indicate that SHP acts as a novel positive regulator of bone formation by augmenting osteoblast differentiation through regulation of the transcriptional activity of Runx2. © 2010 American Society for Bone and Mineral Research
Gene expression profiling in monocytes and SNP association suggest the importance of theSTAT1gene for osteoporosis in both Chinese and Caucasians
Authors: Chen Xiang-Ding , Xiao Peng , Lei Shu-Feng , Liu Yao-Zhong , Guo Yan-Fang , Deng Fei-Yan , Tan Li-Jun , Zhu Xue-Zhen , Chen Fu-Rong , Recker Robert R. , Deng Hong-Wen
Published: July 2009

Osteoporosis is characterized mainly by low bone mineral density (BMD). Many cytokines and chemokines have been related with bone metabolism. Monocytes in the immune system are important sources of cytokines and chemokines for bone metabolism. However, no study has investigated in vivo expression of a large number of various factors simultaneously in human monocytes underlying osteoporosis. This study explored the in vivo expression pattern of general cytokines, chemokines, and their receptor genes in human monocytes and validated the significant genes by qRT-PCR and genetic association analyses. Expression profilings were performed in monocyte samples from 26 Chinese and 20 Caucasian premenopausal women with discordant BMD. Genome-wide association analysis with BMD variation was conducted in 1000 unrelated Caucasians. We selected 168 cytokines, chemokines, osteoclast-related factors, and their receptor genes for analyses. Significantly, the signal transducer and activator of transcription 1 (STAT1) gene was upregulated in the low versus the high BMD groups in both Chinese and Caucasians. We also revealed a significant association of the STAT1 gene with BMD variation in the 1000 Caucasians. Thus we conclude that the STAT1 gene is important in human circulating monocytes in the etiology of osteoporosis. © 2010 American Society for Bone and Mineral Research
Genome-wide association study for femoral neck bone geometry
Authors: Zhao Lan-Juan , Liu Xiao-Gang , Liu Yao-Zhong , Liu Yong-Jun , Papasian Christopher J , Sha Bao-Yong , Pan Feng , Guo Yan-Fang , Wang Liang , Yan Han , Xiong Dong-Hai , Tang Zi-Hui , Yang Tie-Lin , Chen Xiang-Ding , Guo Yan , Li Jian , Shen Hui , Zhang Feng , Lei Shu-Feng , Recker Robert R , Deng Hong-Wen
Published: July 2009

Poor femoral neck bone geometry at the femur is an important risk factor for hip fracture. We conducted a genome-wide association study (GWAS) of femoral neck bone geometry, examining approximately 379,000 eligible single-nucleotide polymorphisms (SNPs) in 1000 Caucasians. A common genetic variant, rs7430431 in the receptor transporting protein 3 (RTP3) gene, was identified in strong association with the buckling ratio (BR, P = 1.6 × 10−7), an index of bone structural instability, and with femoral cortical thickness (CT, P = 1.9 × 10−6). The RTP3 gene is located in 3p21.31, a region that we found to be linked with CT (LOD = 2.19, P = 6.0 × 10−4) in 3998 individuals from 434 pedigrees. The replication analyses in 1488 independent Caucasians and 2118 Chinese confirmed the association of rs7430431 to BR and CT (combined P = 7.0 × 10−3 for BR and P = 1.4 × 10−2 for CT). In addition, 350 hip fracture patients and 350 healthy control individuals were genotyped to assess the association of the RTP3 gene with the risk of hip fracture. Significant association between a nearby common SNP, rs10514713 of the RTP3 gene, and hip fracture (P = 1.0 × 10−3) was found. Our observations suggest that RTP3 may be a novel candidate gene for femoral neck bone geometry. © 2010 American Society for Bone and Mineral Research
Prospective assessment of thoracic kyphosis in postmenopausal women with osteoporosis
Authors: Roux Christian , Fechtenbaum Jacques , Kolta Sami , Said-Nahal Roula , Briot Karine , Benhamou Claude-Laurent
Published: July 2009

We attempt to assess quantitatively thoracic kyphosis and its influence on incident fractures and quality of life over three years in postmenopausal women with osteoporosis and the effect of strontium ranelate on thoracic kyphosis progression. This study was performed on women with postmenopausal osteoporosis from the Spinal Osteoporosis Therapeutic Intervention (SOTI) and Treatment of Peripheral Osteoporosis (TROPOS) studies. Vertebral fractures were assessed on lateral thoracic radiographs performed at baseline and at three years according to standardized procedure. Kyphosis index (KI, %), was defined as the percentage ratio between the maximum depth of thoracic curvature and the height measured from the T4 to the T12 vertebrae. Baseline characteristics of the 3218 patients (1594 strontium ranelate, 1624 placebo) were mean age 73.3 years, spine bone mineral density (BMD) T-score (L2–4) −3.1, femoral neck T-score −3.0, and KI 25.4%. In the placebo group, patients with the highest baseline KI experienced significantly more vertebral fractures than those with medium KIs [relative risk (RR) = 1.53; 95% confidence interval (CI) 1.19–1.96, p < .001) or the lowest KIs (RR = 1.70, 95%CI 1.32–2.21, p < .001), even after adjusting for the presence of prevalent fractures, age, body mass index (BMI), and BMD. There was no difference in the risk of nonvertebral fractures according to baseline KI. Three-year changes in quality-of-life physical scores reflected significantly better status for patients in the lowest tertile of KI compared with those in the highest at baseline. Over three years, the KI increased for all patients, indicating worsening of thoracic kyphosis, whatever the presence of prevalent or incident vertebral fractures. This KI progression was lower in the strontium ranelate group than in the placebo group. Thoracic kyphosis is a risk factor for vertebral fractures over three years and influences physical capacity changes in postmenopausal women with osteoporosis. Thoracic kyphosis progression over three years is lower in a subgroup of strontium ranelate–treated patients compared with placebo-treated patients. © 2010 American Society for Bone and Mineral Research
A new familial sclerosing bone dysplasia
Authors: Chouery Eliane , Pangrazio Alessandra , Frattini Annalisa , Villa Anna , Van Wesenbeeck Liesbeth , Piters Elke , Van Hul Wim , Coxon Fraser P , Schouten Tabitha , Helfrich Miep , Lefranc Gérard , Mégarbané André
Published: July 2009

Osteoscleroses are a heterogeneous group of bone remodeling disorders characterized by an increase in bone density. Here we report on a consanguineous Lebanese family in which two sisters, aged 39 and 36 years, exhibit a severe genu varum, a square-face appearance, high forehead, slight proptosis of the eyes, symmetric enlargement of the jaw, protruding chin, and short stature. Bone X-rays showed the presence of hyperostosis of the cranial base and vault with increased density of the orbits, hyperostosis of the bones, thickening of the cortices, diaphyseal modeling defects, cortical thickening of the medullary cavity, mild enlargement of the medullary cavity of the short long bones, short femoral necks, increased width of the ribs, and narrow interpedicular distances of the lower lumbar spine. Osteodensitometry showed values 200% to 300% above values for age. A cervical MRI revealed the presence of a diffuse osteosclerosis with calcification of the posterior vertebral ligament and a narrow canal between C2 and T2. Blood test results were unremarkable. Serum osteocalcin levels were in the normal range, whereas high values of serum C-telopeptide were noted. A bone biopsy showed only the presence of compact bone and did not allow for histomorphometric analysis. Molecular studies excluded genes known to be involved in sclerosing bone dysplasias as the cause of this condition. In vitro analysis of osteoclast function indicated that contrary to most cases of autosomal recessive osteopetrosis, osteoclasts both formed and resorbed but exhibited a small decrease in resorptive activity compared with osteoclasts generated from normal control individuals. Differential diagnoses are discussed, and the possibility that this may be a novel clinical entity is raised. © 2010 American Society for Bone and Mineral Research.
Changing structure of the femoral neck across the adult female lifespan
Authors: Poole Kenneth ES , Mayhew Paul M , Rose Collette M , Brown J Keenan , Bearcroft Philip J , Loveridge Nigel , Reeve Jonathan
Published: July 2009

The anatomic distribution of cortical and cancellous bone in the femoral neck may be critical in determining resistance to fracture. We investigated the effects of aging on femoral neck bone in women. In this cross-sectional study, we used clinical multidetector computed tomography (MDCT) of the hips to investigate aging effects in 100 female volunteers aged 20 to 90 years. We developed a clinically efficient protocol to measure cortical thickness (C.Th) and cortical, trabecular, and integral bone mineral density (CtBMD, TrBMD, and iBMD in mg/cm3) in anatomic quadrants of the femoral neck. We used a nested ANOVA to evaluate their associations with height, weight, location in the femoral neck, and age of the subject. Age was the principal determinant of both cortical thickness and BMD. Age had significantly different effects within the anatomic quadrants; compared with young women, elderly subjects had relative preservation of the inferoanterior (IA) quadrant but strikingly reduced C.Th and BMD superiorly. A model including height, weight, and region of interest (and their interactions) explained 83% of the measurement variance (p < .0001). There were marked C.Th and BMD differences between age 25 and age 85 in the already thin superior quadrants. At 25 years the predicted C.Th of the superoposterior quadrant was 1.63 mm, whereas at 85 years it was 0.33 mm [−1.33 mm, 95% confidence interval (CI) of difference over 60 years −1.69 to −0.95]. By contrast, at 25 years mean C.Th of the IA quadrant was 3.9 mm, whereas at 85 years it was 3.3 mm (−0.6 mm, 95% CI −0.83 to −0.10). CtBMD of the IA region was equivalent at 25 and 85 years. In conclusion, elderly women had relative preservation of IA femoral neck bone over seven decades compared with young women but markedly lower C.Th and BMD in the other three quadrants. The IA quadrant transmits mechanical load from walking. Mechanical theory and laboratory tests on cadaveric femurs suggest that localized bone loss may increase the risk of fracture in elderly fallers. It remains to be determined whether this MDCT technique can provide better prediction of hip fracture than conventional clinical dual X-ray absorptiometry (DXA). © 2010 American Society for Bone and Mineral Research