bluuebunny/crossref_metadata_2025 huggingface dataset:
Expression of either Lethal Toxin or Edema Toxin by Bacillus anthracis Is Sufficient for Virulence in a Rabbit Model of Inhalational Anthrax
Authors: Lovchik Julie A. , Drysdale Melissa , Koehler Theresa M. , Hutt Julie A. , Lyons C. Rick
Published: April 2012

The development of therapeutics against biothreats requires that we understand the pathogenesis of the disease in relevant animal models. The rabbit model of inhalational anthrax is an important tool in the assessment of potential therapeutics against
Bacillus anthracis
. We investigated the roles of
B. anthracis
capsule and toxins in the pathogenesis of inhalational anthrax in rabbits by comparing infection with the Ames strain versus isogenic mutants with deletions of the genes for the capsule operon (
capBCADE
), lethal factor (
lef
), edema factor (
cya
), or protective antigen (
pagA
). The absence of capsule or protective antigen (PA) resulted in complete avirulence, while the presence of either edema toxin or lethal toxin plus capsule resulted in lethality. The absence of toxin did not influence the ability of
B. anthracis
to traffic to draining lymph nodes, but systemic dissemination required the presence of at least one of the toxins. Histopathology studies demonstrated minimal differences among lethal wild-type and single toxin mutant strains. When rabbits were coinfected with the Ames strain and the PA− mutant strain, the toxin produced by the Ames strain was not able to promote dissemination of the PA− mutant, suggesting that toxigenic action occurs in close proximity to secreting bacteria. Taken together, these findings suggest that a major role for toxins in the pathogenesis of anthrax is to enable the organism to overcome innate host effector mechanisms locally and that much of the damage during the later stages of infection is due to the interactions of the host with the massive bacterial burden.
Vibrio cholerae Classical Biotype Strains Reveal Distinct Signatures in Mexico
Authors: Alam Munirul , Islam M. Tarequl , Rashed Shah Manzur , Johura Fatema-tuz , Bhuiyan Nurul A. , Delgado Gabriela , Morales Rosario , Mendez Jose Luis , Navarro Armando , Watanabe Haruo , Hasan Nur-A , Colwell Rita R. , Cravioto Alejandro
Published: April 2012

Vibrio cholerae
O1 classical (CL) biotype caused the fifth and sixth pandemics, and probably the earlier cholera pandemics, before the El Tor (ET) biotype initiated the seventh pandemic in Asia in the 1970s by completely displacing the CL biotype. Although the CL biotype was thought to be extinct in Asia and although it had never been reported from Latin America,
V. cholerae
CL and ET biotypes, including a hybrid ET, were found associated with areas of cholera endemicity in Mexico between 1991 and 1997. In this study, CL biotype strains isolated from areas of cholera endemicity in Mexico between 1983 and 1997 were characterized in terms of major phenotypic and genetic traits and compared with CL biotype strains isolated in Bangladesh between 1962 and 1989. According to sero- and biotyping data, all
V. cholerae
strains tested had the major phenotypic and genotypic characteristics specific for the CL biotype. Antibiograms revealed the majority of the Bangladeshi strains to be resistant to trimethoprim-sulfamethoxazole, furazolidone, ampicillin, and gentamicin, while the Mexican strains were sensitive to all of these drugs, as well as to ciprofloxacin, erythromycin, and tetracycline. Pulsed-field gel electrophoresis (PFGE) of NotI-digested genomic DNA revealed characteristic banding patterns for all of the CL biotype strains although the Mexican strains differed from the Bangladeshi strains in 1 to 2 DNA bands. The difference was subtle but consistent, as confirmed by the subclustering patterns in the PFGE-based dendrogram, and can serve as a regional signature, suggesting the pre-1991 existence and evolution of the CL biotype strains in the Americas, independent from Asia.
Coccidioides Thyroiditis in an HIV-Infected Patient
Authors: Jinno Sadao , Chang Shelley , Jacobs Michael R.
Published: April 2012

We report a case of
Coccidioides
thyroiditis in an HIV-infected patient with a history of recent
Coccidioides
pneumonia but with negative
Coccidioides
serology determined by enzyme immunoassay at presentation. Diagnosis of
Coccidioides
thyroiditis was made based on histopathologic examination and culture of thyroid abscess material obtained by fine-needle aspiration biopsy.
Comparison of the Luminex xTAG RVP Fast Assay and the Idaho Technology FilmArray RP Assay for Detection of Respiratory Viruses in Pediatric Patients at a Cancer Hospital
Authors: Babady N. Esther , Mead Peter , Stiles Jeffrey , Brennan Carrie , Li Haijing , Shuptar Susan , Stratton Charles W. , Tang Yi-Wei , Kamboj Mini
Published: April 2012

Respiratory viruses are increasingly recognized as serious causes of morbidity and mortality in immunocompromised patients. The rapid and sensitive detection of respiratory viruses is essential for the early diagnosis and administration of appropriate antiviral therapy, as well as for the effective implementation of infection control measures. We compared the performance of two commercial assays, xTAG RVP Fast (Luminex Diagnostics, Toronto, Canada) and FilmArray RVP (FA RVP; Idaho Technology, Salt Lake City, UT), in pediatric patients at Memorial Sloan-Kettering Cancer Center. These assays detect the following viruses: respiratory syncytial virus; influenza A and B viruses; parainfluenza viruses 1, 2, 3, and 4; human metapneumovirus; adenovirus; enterovirus-rhinovirus; coronaviruses NL63, HKU1, 229E, and OC43; and bocavirus. We tested a total of 358 respiratory specimens from 173 pediatric patients previously tested by direct fluorescence assay (DFA) and viral culture. The overall detection rate (number of positive specimens/total specimens) for viruses tested by all methods was 24% for DFA/culture, 45% for xTAG RVP Fast, and 51% for FA RVP. The agreement between the two multiplex assays was 84.5%, and the difference in detection rate was statistically significant (P< 0.0001). Overall, the FA RVP assay was more sensitive than the xTAG RVP Fast assay and had a turnaround time of approximately 1 h. The sensitivity, simplicity, and random-access platform make FA RVP an excellent choice for laboratory on-demand service with low to medium volume.
Antimicrobial Resistance, Toxinotype, and Genotypic Profiling of Clostridium difficile Isolates of Swine Origin
Authors: Fry Pamela R. , Thakur Siddhartha , Abley Melanie , Gebreyes Wondwossen A.
Published: April 2012

The occurrence of
Clostridium difficile
infections in patients that do not fulfill the classical risk factors prompted us to investigate new risk factors of disease. The goal of this study was to characterize strains and associated antimicrobial resistance determinants of
C. difficile
isolated from swine raised in Ohio and North Carolina. Genotypic approaches used include PCR detection, toxinotyping, DNA sequencing, and pulsed-field gel electrophoresis (PFGE) DNA fingerprinting. Thirty-one percent (37/119) of isolates carried both
tetM
and
tetW
genes. The
ermB
gene was found in 91% of isolates that were resistant to erythromycin (68/75). Eighty-five percent (521/609) of isolates were toxin gene
tcdB
and
tcdA
positive. A total of 81% (494/609) of isolates were positive for
cdtB
and carry a
tcdC
gene (a toxin gene negative regulator) with a 39-bp deletion. Overall, 88% (196/223) of pigs carry a single
C. difficile
strain, while 12% (27/223) of pigs carried multiple strains. To the best of our knowledge, this is the first report of individual pigs found to carry more than one strain type of
C. difficile
. A significant difference in toxinotype profiles in the two geographic locations was noted, with a significantly (
P
< 0.001) higher prevalence of toxinotype V found in North Carolina (84%; 189/224) than in Ohio (55%; 99/181). Overall, the study findings indicate that significant proportions of
C. difficile
in swine are toxigenic and often are associated with antimicrobial resistance genes, although they are not resistant to drugs that are used to treat
C. difficile
infections.
Babies born at the threshold of viability: changes in survival and workload over 20 years
Authors: Seaton Sarah E , King Sophie , Manktelow Bradley N , Draper Elizabeth S , Field David J
Published: April 2012

Objective

To assess the care given to the babies born at the threshold of viability over the last 20 years using regional and national data.

Design

Population-based retrospective study.

Setting

Former ‘Trent’ health region.

Participants

Babies born between 1 January 1991 and 31 December 2010 at 22+0to 25+6weeks gestational age.

Main outcome measure

Survival and use of respiratory support.

Methods

Data of all babies born between 1 January 1991 and 31 December 2010 with a gestational age of 22+0to 25+6weeks and admitted to a neonatal unit were extracted from The Neonatal Survey. Use of respiratory support in terms of ventilation and continuous positive airway pressure (CPAP) for this group of babies was calculated as a proportion of the total used by the whole neonatal intensive care population within the defined study area.

Results

The proportion of babies surviving to discharge increased significantly over time in those born at 24 and 25 weeks (p<0.01) but failed to achieve statistical significance for those at 23 weeks (p=0.08). No babies born at 22 weeks survived. The babies born at 22–25 weeks accounted for 26.3% of all ventilation and 21.5% of CPAP given.

Conclusion

Our work concurs with the current UK guidelines. There could be advantages in focusing the care of babies born at 23 weeks to a small number of intensive care units to allow specialist expertise to develop in all aspects of the management of these babies. However, focusing care will not necessarily improve survival or reduce morbidity.
THE SUPERSYMMETRIC TWO-LOOP CORRECTIONS TO MUON MAGNETIC DIPOLE MOMENTS IN THE CP-VIOLATING MSSM
Authors: ZHAO SHU-MIN , FENG TAI-FU , LI TONG , LI XUE-QIAN , SUN KE-SHENG
Published: April 2012

Using the effective Lagrangian method, we study the electroweak corrections to the magnetic dipole moment of muon from some special two-loop topological diagrams which are composed of chargino–sneutrino, neutralino–slepton, slepton–sneutrino, in the CP-violating minimal supersymmetric extension of the standard model. Considering the electromagnetic gauge invariance, we obtain the Wilson coefficients of those dimension 6 operators which induce the magnetic dipole moment of leptons. Adopting the zero-momentum substraction scheme, we remove the ultra-violet divergences induced by the divergent sub-diagrams. The numerical results indicate that the two-loop supersymmetric corrections from this sector to the muon magnetic dipole moment can exceed 10-10, which is the same order of present experimental precision.
EFFECT OF SPATIAL PERCOLATION ON THE CONVERGENCE OF A GRAPH COLORING BOID SWARM
Authors: REBOLLO ISRAEL , GRAÑA MANUEL , CASES BLANCA
Published: April 2012

Graph Coloring Boid Swarm (GCBS) is the successful application of Reynolds' Boid Swarm to solve the graph coloring problem, following appropriate mapping of the problem into boids' behaviors and interpretation of the global swarm states as problem solutions. A population P of boids moves in a closed torus-shaped space S. Each individual boid perceives a disk of radius R of its surrounding space, being able to exchange information with other boids lying inside this area of perception. Two mutually perceiving boids exchanging information are connected. In this paper we show that the ratio of the radius of perception to the space size can be critical for the convergence of the Boid Swarm to the optimal configurations. First, we derive the Percolation threshold for Elementary Boid Swarms (EBS), whose dynamics are the aggregation of the boids into spatial clusters. When the radius of perception is above this percolation threshold for Elementary Boid Swarms (EBS), whose dynamics are the aggregation of the boids into spatial clusters. When the radius of perception is above this percolation threshold there is complete connectivity and convergence to a single cluster. Second, we show empirically the existence of such a Percolation effect on the Graph Coloring Boid Swarm (GCBS). We find that complete connectivity has an adverse effect on the performance of the GCBS. Finally we show a comparison of GCBS with some other algorithms over a family of generated graphs.
A MODEL BASED ON INFLUENCE DIAGRAMS FOR MULTI-CRITERIA DECISION-MAKING
Authors: SEDKI KARIMA , DELCROIX VÉRONIQUE
Published: April 2012

In this paper, we focus on multi-criteria decision-making problems. We propose a model based on influence diagrams; this model is able to handle uncertainty, represent interdependencies among the different decision variables and facilitate communication between the decision-maker and the analyst. The particular structure of the proposed model makes it possible to take into account the alternatives described by an attribute set, the decision-maker's characteristics and preferences, and other information (e.g., internal or external factors) that influence the decision. Modeling the decision problem in terms of influence diagrams requires a lot of work to gather expert knowledge. However, once the model is built, it can be easily and efficiently used for different instances of the decision problem. In fact, using our model simply requires entering some basic information, such as the values of internal or external factors and the decision-maker's characteristics. Our model also defines the importance of each criterion in terms of what is known about the decision maker, the quality index and the utility of each alternative.
A RELATIONAL RANKING METHOD WITH GENERALIZATION ANALYSIS
Authors: PENG ZEWU , PAN YAN , TANG YONG , CHEN GUOHUA
Published: April 2012

Recently, learning to rank, which aims at constructing a model for ranking objects, is one of the hot research topics in information retrieval and machine learning communities. Most of existing learning to rank approaches are based on the assumption that each object is independently and identically distributed. Although this assumption simplifies ranking problems, the implicit interconnections between objects are ignored. In this paper, a graph based ranking framework is proposed, which takes advantage of implicit correlations between objects. Furthermore, the derived relational ranking algorithm from this framework, called GRSVM, is developed based on the conventional algorithm RankSVM-primal. In addition, generalization properties of different relational ranking algorithms are analyzed using Rademacher Average. Based on the analysis, we find that GRSVM can achieve tighter generalization bound than existing relational ranking algorithms in most cases. Finally, a comparison of experimental results produced by improved and conventional algorithms shows the superior performance of the former.
NONADIABATIC TRANSITION OF THE FISSIONING NUCLEUS AT SCISSION: THE TIME SCALE
Authors: CARJAN N. , RIZEA M.
Published: April 2012

A time-dependent approach to the scission process, i.e., to the transition from two fragments connected by a thin neck (deformation αi) to two separated fragments (deformation αf) is presented. This transition is supposed to take place in a very short time interval ΔT. Our approach follows the evolution from αi to αf of all occupied neutron states by solving numerically the two-dimensional time-dependent Schrödinger equation with time-dependent potential. Calculations are performed for mass divisions from AL = 70 to AL = 118(AL being the light fragment mass) taking into account all neutron states (Ω = 1/2, 3/2, …, 11/2) that are bound in 236 U at αi. ΔT is taken as parameter having values from 0.25×10-22 to 6×10-22 s. The resulting scission neutron multiplicities ν sc and primary fragments' excitation energies [Formula: see text] are compared with those obtained in the frame of the sudden approximation (ΔT = 0). As expected, shorter is the transition time more excited are the fragments and more neutrons are emitted, the sudden approximation being an upper limit. For ΔT = 10-22 which is a realistic value, the time dependent results are 20% below this limit. For transition times longer than 6×10-22 s the adiabatic limit is reached: No scission neutrons are emitted anymore and the excitation energy at αf is negligible.
MELORHEOSTOSIS: CURRENT CONCEPTS IN DIAGNOSIS AND TREATMENT — A REVIEW OF LITERATURE (313 CASES)
Authors: Artner J. , Cakir B. , Wernerus D. , Reichel H. , Nelitz M.
Published: April 2012

Melorheostosis is a rare condition of bone and surrounding tissues with different clinical presentations, ranging from clinically inapparent radiographic incidental findings to deformity, resistant chronic pain, swelling, restricted range of motion of the affected joints, leg length discrepancy or even cervical myelopathy. It is characterized by a hyperostosis of long or short bones. It is often associated with cutaneous and vascular changes like naevi, haemangiomas, scleroderma, lymphedema and arteriovenous malformations. Pain is the most common symptom of the condition. The therapy is individual and depends on the clinical manifestation. There are about 350 cases described in the literature until today. The current article presents an actual and most comprehensive review of literature to this rare condition, including 313 cases, focusing on symptomatology, diagnostic steps and the therapeutic options.
USING RIGIDITY ANALYSIS TO PROBE MUTATION-INDUCED STRUCTURAL CHANGES IN PROTEINS
Authors: JAGODZINSKI FILIP , HARDY JEANNE , STREINU ILEANA
Published: April 2012

Predicting the effect of a single amino acid substitution on the stability of a protein structure is a fundamental task in macromolecular modeling. It has relevance to drug design and understanding of disease-causing protein variants. We present KINARI-Mutagen, a web server for performing in silico mutation experiments on protein structures from the Protein Data Bank. Our rigidity-theoretical approach permits fast evaluation of the effects of mutations that may not be easy to perform in vitro, because it is not always possible to express a protein with a specific amino acid substitution. We use KINARI-Mutagen to identify critical residues, and we show that our predictions correlate with destabilizing mutations to glycine. In two in-depth case studies we show that the mutated residues identified by KINARI-Mutagen as critical correlate with experimental data, and would not have been identified by other methods such as Solvent Accessible Surface Area measurements or residue ranking by contributions to stabilizing interactions. We also generate 48 mutants for 14 proteins, and compare our rigidity-based results against experimental mutation stability data. KINARI-Mutagen is available at http://kinari.cs.umass.edu .
Hong Kong Politics: Diminished Government Credibility and Heightened Political Awareness
Authors: KWONG Kin-ming , YEW Chiew Ping
Published: April 2012

After two Chief Executive leadership, it is evident that Hong Kong has been ruled by polling, not the government, as seen in the policy U-turns in 2011. The government has failed to build public confidence in its leadership despite achievements such as raising Hong Kong's GDP per capita by 22% under Tsang's administration. A historically high proportion of people since the handover had identified themselves as Hong Kongers rather than Chinese citizens in June 2011.
Taiwan's Economy: Slower Growth and Further Dependence on China
Authors: CHIANG Min-hua
Published: April 2012

The Taiwanese government forecasted economic growth to dip from 10.7% in 2010 to about four per cent in 2011 and 3.9% in 2012. Reasons for the dip were the earthquake on 11 March 2011 in Japan and the weak demand from Europe and US markets, a situation which is expected to affect the Taiwan economy in 2012. Nonetheless, cross-strait economic relations are likely to progress further after Kuomintang's victory in the 2012 presidential election.
China's Recent Discussions of Political Reform and Leadership Responses
Authors: WU Guoguang
Published: April 2012

Discussions around political reform have reemerged among Chinese intellectuals. Officially, the Beijing leadership has not responded to these discussions. However, its response came in the form of ideological propaganda as indirect criticism of the discussions, political repression over the discussions, positive consonance with the discussions and advocation of the Maoist practice as an alternative to political reform. It is highly doubtful that the 18th Party Congress will adopt a systematic plan of political reform.
Water-Related Hole Traps at Thermally Grown GeO2–Ge Interface
Authors: Oniki Yusuke , Ueno Tomo
Published: April 2012

The generation mechanism of positive charge present in germanium oxide film thermally grown on a germanium substrate has been investigated in this study. Water-related hole traps are generated in the interfacial germanium suboxide layer. The negative flat-band voltage shift due to the charged hole traps increases with increasing electric stress field in the oxide. Both low-temperature growth of the oxide film and postmetallization annealing have been proposed for the improvement of the flat-band voltage shift. The former is effective in minimizing the suboxide layer thickness by suppressing germanium monoxide volatilization during the oxide growth. The latter method successfully reduces the density of traps caused by water desorption from the interfacial suboxide layer.
Passivation of Ge(100) and (111) Surfaces by Termination of Nonmetal Elements
Authors: Lee DongHun , Kubo Kazuki , Kanashima Takeshi , Okuyama Masanori
Published: April 2012

The passivation of the Ge surface is an important issue for a high-performance transistor. Therefore, we carried out the theoretical and experimental analyses to search for alternative terminal materials on the Ge surface. First, the chemical reactivities of various nonmetal elements on the Ge surface were simulated by the semi empirical molecular orbital method to passivate the Ge(100) and (111) surface dangling bonds. The simulations showed that F, Cl, and Se are more useful for the treatment of the Ge(100) surface and that F, Cl, S, and Se are more stable on the Ge(111) surface than H. In particular, S is more effective in terminating the dangling bonds by forming a bridge bond (Ge–S–Ge) and more stable on the Ge(111) surface than on the Ge(100) surface. Next, for experimental confirmation, we performed an (NH4)2S solution treatment method on the p-type Ge(100) and (111) substrates, and fabricated HfO2/p-Ge metal–insulator–semiconductor (MIS) devices by photo assisted metal organic chemical vapor deposition (MOCVD). As a result, the S-treatment using (NH4)2S solution improved more the electrical properties of the HfO2/p-Ge(111) MIS capacitor than those of the capacitor on the Ge(100) substrate. Recently, the sulfur treatment of the Ge surface has been mainly focused on the Ge(100) substrate. However, the results of this study show that the sulfur treatment method using (NH4)2S solution is more useful on the Ge(111) surface than on the Ge(100) surface.
Fabrication of Graphene Directly on SiO2 without Transfer Processes by Annealing Sputtered Amorphous Carbon
Authors: Sato Motonobu , Inukai Manabu , Ikenaga Eiji , Muro Takayuki , Ogawa Shuichi , Takakuwa Yuji , Nakano Haruhisa , Kawabata Akio , Nihei Mizuhisa , Yokoyama Naoki
Published: April 2012

We fabricated multilayer graphene directly on SiO2 by annealing sputtered amorphous carbon with a catalyst – a simple non-chemical vapor deposition method – without the use of complicated transfer processes. Structural analysis revealed that the graphene sheets formed an epitaxial structure aligned to the Co(111) surface between the Co catalyst and SiO2 dielectric. In the multilayer graphene, a resistivity of approximately 500 µΩ cm was obtained, which is one order of magnitude higher than that of highly oriented pyrolytic graphite.
Through Silicon Via Fabrication with Low-κ Dielectric Liner and Its Implications on Parasitic Capacitance and Leakage Current
Authors: Zhang Lin , Lim Dau Fatt , Li Hong Yu , Gao Shan , Tan Chuan Seng
Published: April 2012

Through silicon via (TSV) has emerged as an essential enabler for three-dimensional integrated circuit (3D IC). The basic TSV structure consisting of a via hole in the Si substrate filled with metal such as copper and lined with a dielectric liner, forms a metal–oxide–silicon (MOS) capacitor structure. To benefit the performance of 3D IC, the TSV used to interconnect vertically stacked dies must introduce small electrical parasitic, such as capacitance. The isolation property of the dielectric liner must also be preserved to control the leakage current. In this work, TSV with acceptable sidewall roughness is achieved and lined with low-κ material with an effective dielectric constant of ∼2.8. Low-κ liner with conformal step coverage is successfully achieved in our fabrication process. Based on electrical measurement, it is found that the integration of the low-κ liner reduces the TSV capacitance by ∼27.6% as compared with the conventional plasma-enhanced tetraethylorthosilicate (PETEOS) oxide liner. In addition, current–voltage (I–V) measurement is carried out to monitor and study the leakage of the low-κ liner. No abrupt breakdown is observed until at least at an electric field of 3 MV/cm which corresponds to 60 V. Annealing of the TSV structure in forming gas (N2/H2) at 350 °C for 30 min successfully reduces the leakage current density by ∼1.6×, to a mid-distribution value of ∼6.8×10-6 A/cm2.
Board-Level Solder Joint Reliability of Edge- and Corner-Bonded Lead-Free Chip Scale Package Assemblies Subjected to Thermal Cycling
Authors: Shi Hongbin , Tian Cuihua , Ueda Toshitsugu
Published: April 2012

In this paper, we present the results of thermal cycling test for edge- and corner-bonded lead-free chip scale packages (CSPs), which was carried out on the basis of the IPC-9701 test standard. Six materials were used in this study: four edge-bond adhesives and two corner-bond adhesives. These adhesives were compared with CSPs with full capillary flow underfill (FCFU) and without adhesives. The thermal cycling test results show that corner-bond adhesive has comparable solder joint reliability performance with CSP without adhesive, and is better than edge-bond adhesive, followed by CSPs with FCFU. In addition, the adhesives with a low coefficient of thermal expansion, a high glass transition temperature and a intermediate storage modulus yielded good performance. Results of detailed failure analysis indicate that the dominant failure mode is solder bulk fatigue cracking near package and/or printed circuit board (PCB) pads, and that the location of critical solder joints change from die edges to package corners with the introduction of adhesives.
Random Interface-Traps-Induced Electrical Characteristic Fluctuation in 16-nm-Gate High-κ/Metal Gate Complementary Metal–Oxide–Semiconductor Device and Inverter Circuit
Authors: Li Yiming , Cheng Hui-Wen
Published: April 2012

This work estimates electrical and transfer-characteristic fluctuations in 16-nm-gate high-κ/metal gate (HKMG) metal–oxide–semiconductor field effect transistor (MOSFET) devices and inverter circuit induced by random interface traps (ITs) at high-κ/silicon interface. Randomly generated devices with two-dimensional (2D) ITs at HfO2/Si interface are incorporated into quantum-mechanically corrected 3D device simulation. Device characteristics, as influenced by different degrees of fluctuation, are discussed in relation to random ITs near source and drain ends. Owing to a decreasing penetration of electric field from drain to source, the drain induced barrier lowering (DIBL) of the edvice decreases when the number of ITs increases. In contrast to random-dopant fluctuation, the screening effect of device's inversion layer cannot effectively screen potential's variation; thus, devices still have noticeable fluctuation of gate capacitance (C
G) under high gate bias. The cutoff frequency decreases as increasing the number of ITs owing to the decreasing transconductance and increasing C
G. Decreasing on-state current and increasing C
G further result in increasing intrinsic gate delay time (τ) when the number of ITs increases. The fluctuation magnitude of DIBL, cutoff frequency, and τ above is increased as the number of ITs increases. Even for cases with the same number of random ITs, noise margins (NMs) of the 16-nm-gate complementary metal–oxide–semiconductor inverter circuit are still quite different due to the different distribution of random ITs. The NMs of inverter circuit increase as the number of random ITs increases; however, the NMs' fluctuations are increased due to the more sources of fluctuation at HfO2/Si interface of HKMG devices.
Fabrication of Floating-Gate-Type Fin-Channel Double- and Tri-Gate Flash Memories and Comparative Study of Their Electrical Characteristics
Authors: Liu Yongxun , Kamei Takahiro , Matsukawa Takashi , Endo Kazuhiko , O'uchi Shinichi , Tsukada Junichi , Yamauchi Hiromi , Ishikawa Yuki , Hayashida Tetsuro , Sakamoto Kunihiro , Ogura Atsushi , Masahara Meishoku
Published: April 2012

Floating-gate (FG)-type fin-channel double-gate (DG) and tri-gate (TG) flash memories with different control-gate (CG) lengths (L
CG) from 76 to 256 nm have successfully been fabricated by using (110)-oriented silicon on insulator (SOI) wafers, and their electrical characteristics have been comparatively investigated. It was experimentally found that better short channel effect (SCE) immunity, smaller threshold voltage (V
t) variations, and a higher program speed are obtained in the TG-type flash memories than in the DG-type memories. The higher performance of the TG-type flash memory is partly due to the additional top gate and recessed buried oxide (BOX) region, which strengthen the controllability of the channel potential and increase the coupling ratio of the FG to CG. Moreover, it was also found that the measured source–drain (SD) breakdown voltage (BV
DS) is higher than 3.2 V even when L
CG was reduced to 76 nm. Therefore, the developed fin-channel TG structure is expected to be very useful for the fabrication of scaled NOR-type flash memory.
Re-Examination of Performance and Reliability Degradation in Metal–Oxide–Nitride–Oxide–Semiconductor Memory with Ultrathin SiN Charge Trap Layers
Authors: Kusai Haruka , Morota Misako , Oda Masato , Fujii Shosuke , Sakuma Kiwamu , Koyama Masato
Published: April 2012

We demonstrated that the degradation of program characteristics in metal–oxide–nitride–oxide–semiconductor (MONOS) devices consisting of an ultrathin (∼2 nm) SiN charge trap layer is due to a decrease in the electron capture efficiency, instead of a reduction in the number of available trap sites. From the data retention properties with applied gate bias voltage, we clarified that charge loss through the tunnel layer during data retention becomes more significant with decreasing SiN thickness. These results indicate that to improve the performance and reliability of MONOS devices with an ultrathin SiN charge trap layer, measures must be taken to enhance the capture cross section of the traps and to inhibit carrier motion in the SiN layer simultaneously.
Robust Data Retention and Superior Endurance of Silicon–Oxide–Nitride–Oxide–Silicon-Type Nonvolatile Memory with NH3-Plasma-Treated and Pd-Nanocrystal-Embedded Charge Storage Layer
Authors: Liu Sheng-Hsien , Yang Wen-Luh , Hsiao Yu-Ping , Chao Tien-Sheng
Published: April 2012

In this study, we investigated an ammonia (NH3) plasma-pretreatment (PT) for suppressing the formation of interface states between metal nanocrystals (NCs) and the surrounding dielectric during the NC forming process with the aim of obtaining a highly reliable Pd NC memory. The discharge-based multipulse (DMP) technique was performed to analyze the distribution of trap energy levels in the Pd NCs/Si3N4-stacked storage layer. Through DMP analysis, it is confirmed that the NH3 PT not only significantly increases the quality of the surrounding dielectric of metal NCs but also effectively passivates shallow trap sites in the Si3N4 trapping layer. As compared with the sample without NH3 PT, the NH3-plasma-treated device exhibits better reliability characteristics such as excellent charge retention (only 5% charge loss for 104 s retention time) and very high endurance (no memory window narrowing after 105 program/erase cycles). In addition, the robust multilevel cell retention properties of the NH3-plasma-treated memory are also demonstrated.
Flexible One Diode–One Resistor Crossbar Resistive-Switching Memory
Authors: Huang Jiun-Jia , Hou Tuo-Hung , Hsu Chung-Wei , Tseng Yi-Ming , Chang Wen-Hsiung , Jang Wen-Yueh , Lin Chen-Hsi
Published: April 2012

We report the first demonstration of a flexible one diode–one resistor (1D1R) resistive-switching (RS) memory cell capable of high-density crossbar array implementation at an extremely low cost. A Ti/TiO2/Pt diode with a large rectifying ratio and a stable Ni/HfO2/Pt unipolar RS memory element have been fabricated on a polyimide substrate using only room-temperature processes. No significant degradation of the rectifying ratio of the TiO2 diode and the cycling variations, retention, and read disturb immunity of the HfO2 memory was observed in the bending state. The series 1D1R cell shows highly reproducible unipolar RS because of the low reset current of the HfO2 memory, which greatly mitigates the adverse effect of diode series resistance. Furthermore, the 1D1R cell can effectively suppress read interference and realize a crossbar array as large as 512 kbit.
Experimental Analysis of Within-Die Process Variation in 65 and 180 nm Complementary Metal–Oxide–Semiconductor Technology Including Its Distance Dependences
Authors: Ansari Tania , Imafuku Wataru , Yasuda Masahiro , Mattausch Hans Jürgen , Koide Tetsushi
Published: April 2012

As the very large scale integration (VLSI) circuits move deeper into the range of sub-100 µm processes due to the continued scaling efforts, designers increasingly face the variations of design parameters as major roadblocks. These variations include the deviation of process, voltage, and temperature values from the nominal specifications and are of paramount concern as they result in a deviation of the performance of ICs from the originally intended design. Thus, variations reduce the yield of the chip production and increase design cost and the design timing schedule. In this paper, we are presenting location-based within-die variation trends in 65 nm technology across the die, which are derived from measured delays of adjustable ring oscillators. The measured data of the test chips in a 65 nm complementary metal–oxide–semiconductor (CMOS) technology indicate that the magnitude of the position based relative variation is 3–7 times larger than for 180 nm technology. At low voltage (0.7 V), this relative variation is significantly increased (>3 times) in comparison to the variation at nominal supply voltage.
Impact of Data Transmission over 10 Gbps on High-Density and Low-Cost Optoelectronic Module with Polynorbornene Waveguides
Authors: Ito Yuka , Terada Shinsuke , Arai Shinya , Fujiwara Makoto , Mori Tetsuya , Choki Koji , Fukushima Takafumi , Koyanagi Mitsumasa
Published: April 2012

We proposed a rigid/flex optoelectronic (O/E) module with 48-channel polymeric waveguides for short-distance board-level optical interconnection. A flexible O/E test module was fabricated in the following two steps by using standard packaging processes. First, two vertical cavity surface emitting laser diodes (VCSELs) and one VCSEL driver (VD) were flip-chip bonded to a completed flexible printed circuit board (PCB), and two photodiodes (PDs) and one transimpedance amplifier/limiting amplifier (TIA/LA) to another flexible PCB. Second, the two flexible PCBs were attached with a polynorbornene (PNB) sheet in which high-density PNB waveguides were formed by UV exposure. Active areas of VCSELs and PDs on the flexible PCBs were aligned to micromirrors of the waveguides with -6 µm offset toward the signal propagation direction. We successfully demonstrated data transmission over 10 Gbps and low inter-channel crosstalk of less than -20 dB was achieved in the flexible O/E test module with 120-mm-long and 62.5-µm-pitch waveguides.
Silicon Ring Optical Modulator with p/n Junctions Arranged along Waveguide for Low-Voltage Operation
Authors: Amemiya Yoshiteru , Furutani Ryuichi , Fukuyama Masataka , Yokoyama Shin
Published: April 2012

For low-voltage and high-speed operation, a Si ring optical modulator, where p/n junctions are arranged along the waveguide of the ring resonator, is proposed. In this device, a switching speed of over 30 GHz and a modulation of 3 dB are estimated at a low operation voltage of 1 V by simulation. Optimum design parameters are obtained: the carrier concentration is 1×1018 cm-3 and the length of the p- and n-type regions is 0.4 µm. The modulators were fabricated and the performance was evaluated. The modulation is 1.25 dB at 6 V, which is lower than the simulated value. This is explained by the unexpected low carrier concentration. It is suggested that the optimization of the fabrication process will yield better performance.
Tilted Domain and Indium Content of InGaN Layer on m-Plane GaN Substrate Grown by Metalorganic Vapor Phase Epitaxy
Authors: Shojiki Kanako , Hanada Takashi , Shimada Takaaki , Liu Yuhuai , Katayama Ryuji , Matsuoka Takashi
Published: April 2012

The accurate alloy composition of a nonpolar InGaN grown on m-plane GaN is estimated from X-ray reciprocal-space maps (RSMs) of (202̄1) and (213̄0) diffractions. In this estimation, the anisotropic residual strain in m-plane is carefully considered. In order to avoide the error which may be generated by the anisotropic strain and tilted domains in the film of InGaN, the lattice constants along m-, a-, and c-directions are determined using a pair of two RSMs normalized to the unit reciprocal vector along m-direction. The indium content of InGaN is derived from RSMs data using Poisson effect and Vegard's law. Based on this method, the incorporation of indium into InGaN is investigated. This incorporation is found to be promoted with the increase in the substrate miscut angle and the growth rate. From the precise analysis of RSMs, some of the InGaN domains on m-plane GaN substrates are found to be tilted toward ±a-direction despite of the substrate miscut toward c-direction.
6,13-Bis(triisopropylsilylethynyl) Pentacene Organic Field-Effect Transistors Utilizing Poly(p-silsesquioxane) Insulating Layers with Various Ratios of Phenol Groups
Authors: Nakanishi Yuta , Kajii Hirotake , Tamura Koki , Ohmori Yutaka
Published: April 2012

The effects of the hydroxyl group of polymer gate insulators on the characteristics of p-type 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-pentacene)-based organic field-effect transistors (OFETs) using poly(p-silsesquioxane) (PSQ) derivatives, which contained various ratios of a phenol group with a hydroxyl group bonded to a phenyl ring in the side chain of their molecular structures, were investigated. The hole mobilities of all top-contact bottom-gate-type OFETs with various PSQ insulators were estimated to be on the order of 0.1 cm2 V-1 s-1. The current on/off ratio of an OFET increased with decreasing ratio of the hydroxyl group. The bottom-contact devices with photocrosslinked PSQ insulators containing a low ratio of the phenol group exhibited p-channel FET characteristics with a high field-effect mobility of 0.1 cm2 V-1 s-1 and negligible hysteresis in both output and transfer characteristics. An OFET driven at an operating voltage of 10 V was achieved by using the thin 120-nm-thick photocrosslinked PSQ insulator.
Enhancing the Performance of Pentacene-Based Organic Thin Film Transistors by Inserting Stacked N,N '-Diphenyl-N,N '-bis(1-naphthyl-phenyl)-(1,1'-biphenyl)-4,4'-diamine and Tris(8-hydroxyquinolino)-aluminum Buffer Layers
Authors: Wu Chung-Ming , Su Shui-Hsiang , Weng Wei-Chih , Tsai Hsiang-Lin , Yokoyama Meiso
Published: April 2012

Organic thin-film transistors (OTFTs) were fabricated using various buffer layers between the active layer and source/drain electrodes. The device structure was glass/indium–tin oxide (ITO)/poly(methyl methacrylate) (PMMA)/pentacene/buffer layer/Ag (source/drain). N,N '-diphenyl-N,N '-bis(1-naphthyl-phenyl)-(1,1'-biphenyl)-4,4'-diamine (NPB), tris(8-hydroxyquinolino)-aluminum (Alq3), Alq3/NPB, and NPB/Alq3 films were used as the buffer layers, respectively. The OTFTs using stacked NPB/Alq3 as a buffer layer exhibited a field-effect mobility of 0.31 cm2 V-1 s-1, on–off drain current ratio of 6.7×105, and threshold voltage of -16.8 V. Additionally, the interface mechanism and contact resistance were determined by ultraviolet photoelectron spectroscopy (UPS) and the transmission line method (TLM). Experimental results indicate that a low energy barrier between the electrode and pentacene enhances the ability of holes to transfer from an electrode to pentacene. Moreover, inserting a buffer layer between the electrode and pentacene reduces the contact resistance. Such an improvement is attributed to the weak interface dipole at the interface of the active layer and electrodes.
Diameter Dependence of Sub-Terahertz AC Response of Metallic Carbon Nanotubes with a Single Atomic Vacancy
Authors: Hirai Daisuke , Yamamoto Takahiro , Watanabe Satoshi
Published: April 2012

The sub-THz AC response of metallic single-walled carbon nanotubes (M-SWNTs) with a single atomic vacancy is investigated theoretically focusing on its diameter dependence. We find that the AC response behaves more capacitively in large-diameter M-SWNTs with a vacancy at the center of the SWNT in contrast to the diameter-independent AC response of a pristine M-SWNT showing the inductive response. This can be understood from the fact that the large-diameter M-SWNTs with a vacancy have more scattering states for electrons around the vacancy than the small-diameter ones. In addition, the threshold of vacancy position from the center of the SWNT, beyond which the inductive response appears regardless of the Fermi level position, is higher for large-diameter M-SWNTs than for small-diameter ones. Moreover, we find that the AC response depends strongly on tube diameter, but not on the type of tube, i.e., armchair or zigzag.
Analysis of Operation Mechanism of Field Effect Transistor Composed of Network of High-Quality Single Wall Carbon Nanotubes by Scanning Gate Microscopy
Authors: Wei Xiaojun , Aoki Nobuyuki , Yahagi Tatsurou , Maeda Kenji , Bird Jonathan P. , Ishibashi Koji , Ochiai Yuichi
Published: April 2012

Field effect transistors (FETs) whose channel is composed of a network of high-quality single wall carbon nanotubes (SWNTs) have been studied to investigate the mechanism of the device operation via scanning gate microscopy (SGM) at room temperature. SWNTs synthesized by CoMoCAT® process was used for the formation of the network. Clear SGM responses were observed only at some points but not uniformly in a whole of the channel. The observed responses correspond to positions where two SWNTs are crossing. Back gate voltage dependence of the SGM images and an electrostatic force microscopy image were also studied. One of the possible mechanisms of the SGM response is considered as a modulation of Schottky barrier formed at junctions between metallic and semiconducting SWNTs. Such junctions suggestively play an important role in the FET operation.
A Novel Cost Effective Double Reduced Surface Field Laterally Diffused Metal Oxide Semiconductor Design for Improving Off-State Breakdown Voltage
Authors: Han Ming-Hung , Chen Hung-Bin , Chang Chia-Jung , Wu Jia-Jiun , Chen Wen-Chong , Tsai Chi-Chong , Chang Chun-Yen
Published: April 2012

In this work, double reduced surface field (RESURF) laterally diffused metal oxide semiconductor (LDMOS) device combines a new implant technology without using additional mask in standard 0.18 µm technology has been proposed and successfully fabricated. The breakdown voltage (BV) can be improved significantly with simply changing the implanted region length in this implant technology. Firstly, hydrodynamic transport simulations which analyze the high bias condition electric field distributions are examined to predict and explain the increase of breakdown voltage. Then the fabricated devices process flow is demonstrated, the structures are performed, and the breakdown voltages increase with different n-type double diffusion (NDD) photoresistor (PR) size using the change of PR exposure dose are investigated. The measurement results show that maximum NDD PR size achieves BV improvement of 6.3%, and 5% increase of figure of merit (FOM) evaluation. Throughout the whole fabrication process, no additional mask and device area show the potential of cost effective with the proposed technique. Such devices with good off-state breakdown voltage and specific on-resistance are very competitive with similar technologies and show good promising in system on chip (SOC) applications.
Reconstruction of heterogeneous reservoir architecture based on differential decompaction in sequential re-burial modelling
Authors: Hammer Erik , Brandsegg Kristian Bjarnøe , Mørk Mai Britt E. , Næss Arve
Published: April 2012

A new methodology for robust, high-resolution correlation of reservoir sandstones in highly compactable depositional sequences is proposed. Quantitative sequential re-burial modelling has been successfully applied on real data from seven wells covering the heterogeneous fluviodeltaic Åre Formation in the Heidrun Field, offshore mid-Norway. The methodology is based on ten interpreted lithofacies classes derived from core descriptions and wireline logs signatures, in addition to interpreted sequence stratigraphic surfaces, i.e. flooding surfaces. Analysis of decompacted sedimentary columns, with emphasis on studies of shallow compaction effects tied to uniquely calculated compaction curves, has revealed several new correlatable horizons within the Åre Formation. These include laterally extensive coals and several laterally correlatable fluvial sandstones enabling a reinterpretation of parts of the Åre stratigraphy. The results from the present study demonstrate the benefits of correcting for the effects of differential compaction in well-to-well correlation of heterogeneous reservoirs comprising highly compactable sediments. The methodology outlined here has widespread applicability to other stratigraphic successions and could potentially help in the correlation of highly compacted sediments in the subsurface.
Multidimensional online tracking
Authors: Yi Ke , Zhang Qin
Published: April 2012

We propose and study a new class of online problems, which we call
online tracking
. Suppose an observer, say Alice, observes a multivalued function
f
: Z
+
→ Z

d

over time in an online fashion, that is, she only sees
f
(
t
) for

t≤t
now

where

t
now

is the current time. She would like to keep a tracker, say Bob, informed of the current value of
f
at all times. Under this setting, Alice could send new values of
f
to Bob from time to time, so that the current value of
f
is always within a distance of Δ to the last value received by Bob. We give competitive online algorithms whose communication costs are compared with the optimal offline algorithm that knows the entire
f
in advance. We also consider variations of the problem where Alice is allowed to send predictions to Bob, to further reduce communication for well-behaved functions. These online tracking problems have a variety of application, ranging from sensor monitoring, location-based services, to publish/subscribe systems.