bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hypoxia controls CD4+CD25+ regulatory T‐cell homeostasis via hypoxia‐inducible factor‐1α
Authors: Ben‐Shoshan Jeremy , Maysel‐Auslender Sophia , Mor Adi , Keren Gad , George Jacob 
Published: September 2008

AbstractRecent data suggest that hypoxia and its principal molecular signature HIF‐1 (hypoxia‐inducing factor‐1) may tune down inflammation by dictating anti‐inflammatory programs. We tested the effects of hypoxia and HIF‐1α on the homeostasis of naturally occurring regulatory T cells (Treg) and their transcriptional activator Foxp3. Hypoxia induced a time‐dependent increase in HIF‐1α in mouse and human T cells. Hypoxia upregulated the expression of Foxp3 in Jurkat T cells, human and murine mononuclear cells. The effects of hypoxia on Foxp3 expression were HIF‐1α‐dependent as they were abolished upon transfection with short‐interfering RNAs for HIF‐1α and promoted by HIF‐1α overexpression. Hypoxia increased the potency of Treg, as hypoxic CD4+CD25+ lymphocytes were more effective than normoxic cells in suppressing the proliferation of CD4+CD25− effectors. In vivo expression of HIF‐1α achieved by hydrodynamic injection of the respective naked DNA similarly induced an increase in Foxp3 expression and an increase in the number of functionally active Foxp3+CD4+CD25+ Treg. Thus, hypoxia dictates an anti‐inflammatory program by driving expression of HIF‐1α that acts to increase the number and suppressive properties of naturally occurring CD4+CD25+ Treg.
Insights into Langerhans cell function from Langerhans cell ablation models
Authors: Kaplan Daniel H. , Kissenpfennig Adrien , Clausen Björn E. 
Published: September 2008

AbstractLangerhans cells (LC) are the principal dendritic cell (DC) population in the epidermis of the skin. Owing to their prominent position at the environmental barrier, LC have long been considered to be prototypic sentinel DC. More recently, the precise role of LC in the initiation and control of cutaneous immune responses has become debatable. To elucidate their contribution to immune regulation in the skin, our laboratories have generated genetically modified mice in which LC can be followed in situ by expression of enhanced green fluorescent protein and can be either inducibly or constitutively depleted in vivo. This review highlights the similarities and differences between these mouse models, discusses the discovery and functional significance of Langerin+ dermal DC, and examines some recent data that help to shed light on LC function.
Langerhans cells and viral immunity
Authors: Cunningham Anthony L. , Carbone Francis , Geijtenbeek Teunis B. H. 
Published: September 2008

AbstractLangerhans cells (LC) are a unique dendritic cell subset that are located in mucosal stratified squamous epithelium and skin epidermis. Their location is ideally suited for their function as antigen presenting cells that capture invading viruses and induce anti‐viral immunity. However, it is becoming evident that the interaction between LC and viruses can result in different responses, depending on the virus and the receptors involved. Here we will discuss the recent data on the similarities and differences in roles of LC in viral immunity to and infection with HIV, herpes simplex and varicella–zoster virus. Although all three viruses interact with LC during initial infection, the effects can be quite different, reflecting differences in biology and pathogenesis.
E‐box protein E2‐2 is a crucial regulator of plasmacytoid DC development
Authors: Esashi Eiji , Liu Yong‐Jun 
Published: September 2008

AbstractDC play central roles in priming both innate and adaptive immune responses. Multiple DC subsets have been identified on the basis of their phenotype and function. Plasmacytoid DC (pDC) are professional IFN‐producing cells that play an essential role in anti‐viral immunity. A series of recent studies demonstrates that the regulation of pDC development is different from other types of DC. In this issue of the European Journal of Immunology, new insight is provided into how human pDC development is regulated by various transcription factors, in particular by the Ets family protein Spi‐B and E‐box protein E2‐2.
Cover Picture: Science is multidimensional and very complex. – Eur. J. Immunol. 9/2008
Authors: Minguet Susana , Dopfer Elaine P. , Pollmer Careen , Freudenberg Marina A. , Galanos Chris , Reth Michael , Huber Michael , Schamel Wolfgang W. 
Published: September 2008

AbstractThe cover image was specifically designed based on an illustration provided by Minguet et al., the authors of Enhanced B‐cell activation mediated by TLR4 and BCR crosstalk (pp. 2475–2487). The authors demonstrate that while simultaneous stimulation of TLR4 and BCR activates B cells in an additive manner, antigen‐coupled LPS activates B cells synergistically. The authors proposed this image based on the idea that “science is multidimensional and will never be finished or completely understood”. The
illustration was further enhanced with images taken from various studies published in this issue of the European Journal of Immunology.
Synthesis, Resolution, and Application of Cyclobutyl‐ and Adamantyl‐Quinazolinap Ligands
Authors: Fekner Tomasz , Müller‐Bunz Helge , Guiry Patrick J. 
Published: September 2008

AbstractAn expedient, seven‐step synthesis of two new members of the Quinazolinap ligand family, 2‐cyclobutyl‐ and 2‐(1‐adamantyl)‐Quinazolinaps, has been developed. The racemic ligands have been efficiently resolved by fractional crystallization of their diastereomeric palladacycle complexes. The enantioenriched ligands provide good levels of enantioselection (ee's up to 89 %) in a prototypical PdII‐catalyzed allylic alkylation reaction. 2‐Cyclobutyl‐Quinazolinap has been further functionalized at the 2‐position via metalation with a superbase followed by reaction with a range of electrophiles. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Some characteristics of oogenesis in the female Turkish hamster subjected to modified environments
Authors: Jagiello Georgiana M. , Fang Jye‐Siung , Hembree Wylie C. , Ducayen‐Knowles Mercedes B. 
Published: September 2008

AbstractThe hibernating female Turkish hamster (Mesocricetus brandti) was utilized for a study of possible in vivo effects of cold on oocyte maturation. Such a physiologic model offered an opportunity to analyze the ability of oocytes exposed to prolonged periods of reduced core temperature and/or light to subsequently mature to Metaphase II. Detailed observations of core temperatures, torpor/arousal, serum estradiol, and ovarian histology were made. An average incidence of 37.7% binuclearity was found in the germinal vesicle, metaphase I and II occytes of this species. Maturation to Metaphase II of total chromosome complements did not vary significantly in the experimental groups compared with the control, but aneuploidy was detected in the oocytes of animals exposed to reduced temperature or light. An effect of in vivo reduced core temperatures on oocyte chromosome complements validates many of the published in vitro studies with temperature reduction. The model presents an excellent physiologic system for perturbing and analyzing many aspects of mammalian oocyte development.
Time diversity: A solution for 900 MHz trunking systems
Authors: Velasco Jaime Bustillo , Pliego Miguel Rodriguez‐Palanca 
Published: September 2008

AbstractThe interest into PMR trunking systems is due to the increase of spectral efficiency that can be obtained sharing frequencies between more users. The British DTI protocol specification MPT 1327, intended to be used on this kind of systems, has been recently released, and it is now being accepted as a standard on some european countries.This protocol is based on the MPT 1317 signaling format specification, designed to work at frequencies of 50–500 MHz, and for this reason, it presents some problems when working with RF frequencies of 900 MHz and moving vehicles.The problem comes out from the low bit rate used (1200 bit/s, and the block length (64 bit). If we consider a vehicle that is running at a speed of 100 km/h, we will have a mean of two fades into each information block, while the code (BCH 63, 48) has only a good capacity of error detection/correction for single error bursts.The paper, proposes a solution to this problem, that consists on raising the bit rate to 2400 bit/s, using indirect PSK modulation, with coherect demodulation, instead of FFSK with incoherent demodulation, as it is usual. With this method, we obtain the same BER. Added to this bit rate increase, that allows us to lower the mean number of fades into each block to one, we apply time diversity [2], sending two times each block into the forward control channel, and sending also two times each return control channel or traffic channel message. This diversity system can be implemented bitwise, using channel information to select the most likely value of each bit [4], or block to block, using the error detection capabilities of the code [6].The system has been simulated for 900 MHz and 100 km/h, and measured into a laboratory test setup, using a fading simulator.The results show that proposed method gives the same quality working at 900 MHz that the classic approach working at 150 MHz, showing an improvement of 6 dB over the standard approach working at 900 MHz.
Improved performance in a local area network integrating voice and data
Authors: Marini Michele 
Published: September 2008

AbstractThe performances of a Local Area Network (LAN) integrating voice and data are improved changing the 2 register management in the Reserved Virtual Time CSMA protocol adopted for vocal packets, and using a new exponential backoff algorithm for voice, that introduces a maximum backoff time equal to the vocal packet size involved in the retransmission. In addition, a dynamic priority assignment is used between voice and data, that permits to consider a finite number of buffers for data packets.Simulation results are presented to evaluate LAN performances.
Feasibility of 3D integration
Authors: Sasaki Nohuo 
Published: September 2008

AbstractLaser‐recrystatiization is the best way to fabricate SOI for 3D IC's. Low source‐to‐drain leakage current as small as 3fA/μm is obtained for the SOI MOSFET's with the simple unseeded recrystallization containing grain boundaries. For the 3D CMOS static RAM's, packing density ratio to the conventional 2D CMOS static RAM's is given by 2n/3. and process steps ratio is given by n/3, where n is the device stacking number. The yield and cost OF 3D 1C's are analyzed. The cost of 3D IC's is less than that of 2D IC's at least by a factor of two for static CMOS RAM's, if the yield is determined by such random defects as accidental fine particles. The reason of this is that 3D 1C's do not require some process steps, which are necessary for 2D 1C's to differentiate between n‐ and p‐channel MOSFET's in a single device level.
Modeling of electron beam scattering in high resolution lithography for the fabrication of X‐Ray masks
Authors: Gentili M. , Lucchesini A. , Scopa L. , Lugli P. , Paoletti A. , Messina G. , Santangelo S. , Tucciarone A. 
Published: September 2008

AbstractA single‐layer resist process for X‐ray master mask fabrication by electron beam lithography is theoretically and experimentally investigated. In the mask fabrication process boron nitride membranes are utilized and final absorber structures are obtained by Au electroplating after e‐beam patterning at different primary beam energies, on a single PMMA layer of 10000 A. The e‐beam energies experimentally utilized are 20 and 30 keV. Detailed Monte Carlo analysis of the rnultilayer structure is carried out at 10, 20, 30 and 40 keV, the corresponding proximity function calculated and compared to experiment. It is found that an important source of backscattering is constituted by the thin metal layer as plating base, while the ultimate limit for resolution seems to be determined by forward scattering. Finally, it is demonstrated that by proper selection of the e‐beam energy it is possible to obtain high contrast absorbers down to 0.3 μm lines and spaces.
Charge trapping and interface trap generation in thin nitrided silicon dioxide films for VLSI
Authors: Severi Maurizio , Irnpronta Maurizio , Negrini Paolo , Vassura Stefano 
Published: September 2008

AbstractThis paper presents an extensive review of our work on the charge trapping characterization of thin (10–30 nm) nitrided SiO2 films. Trapping of both electrons and holes, along with generation of interface traps, was studied as a function of the process conditions using the avalanche injection technique. Electron trap generation and time dependent breakdown were also investigated by injecting electrons at high fields. Our results show that, due to the high electron trapping induced by nitridation, interface‐trap generation under electron injection remains higher than that in the reference oxide for all the nitridation conditions experienced. Nitridation also reduces the maximum charge to breakdown, QBD However, after a postnitridation annealing at 1000°C, the electron traps in the oxide nitrided at 900°C can be reduced to such a level that interface trap generation becomes lower than that in the reference oxide. QBD is also greatly improved. Furthermore, hole trapping and interface‐state generation under hole avalanche injection can be reduced by nitridation itself provided it is carried out at relatively high temperatures (>900°C) and for relatively long times (>15 min.). It is thus found that with a careful optimization of the nitridation and postnitridation treatment conditions, a more reliable gate dielectric can be obtained.
Gate oxide thinning as related to doping effects
Authors: Bellutti P. , Claeys C. , Debusschere I. , Corticelli F. , Govoni D. 
Published: September 2008

AbstractGate oxide thinning induced by selective oxidation process has been studied. Tests on samples having both high and low boron doping concentration after wet oxidation of 9 and 50 h, have shown that gate thinning phenomenon is related to substrate doping concentration for p‐type silicon. The chemical resistivity of the nitride or oxynitride layer, which is assumed to be responsible for the gate thinning, has been tested and it also results to be related to the substrate boron concentration. A possible interpretation of the occurrence of the doping effect is given.
Interconnections in application specific VLSI
Authors: Pramanik Dipankar , Spadini Gianpaolo 
Published: September 2008

AbstractProcess technologies developed for the fabrication of Application Specific Integrated Circuits must satisfy some unusual demands imposed by design automation and by fast turn around manufacturing.In this paper we will discuss some of the problems that constrain the selection of a suitable interconnection technology for ASIC's VLSI.Design automation (a tool necessary for ASIC designs) demands a simple set of design rules and very large current carrying capability metal Lines. On the other hand fast turnaround manufacturing requires the use of simple and proven technologies so that the product will be easily manufacturable, possibly in more than one foundry.Some of the available technologies to implement mutilevel interconnections will be reviewed and the one chosen by VLSI Technology for their 1 μm ASIC process will be briefly described.
Multi‐level metallization: Future prospects
Authors: Crannernan E. H. A. 
Published: September 2008

AbstractChemical vapour deposition of tungsten and aluminium films is discussed as alternative to sputtering of aluminium in future multilevel metallization schemes. Because CVD generally offers a very good step coverage it is an attractive technology for filling sub‐micron via's and contact holes. In this paper three CVD‐based metallization scenaria are discussed. The first one is filling of via's with selective (CVD) W followed by sputtering of A1 on the planarized surface. Secondly, blanket deposition of W is discussed and thirdly blanket deposition of (CVD) aluminium.The many problems plaguing selective W such as selectivity loss, encroachment, creep up, etc. are discussed. Selectivity loss is shown to be linked with the presence of reaction by‐products.Aluminium CVD, carried out in a novel type multi‐chamber reactor system is presented as a potentially attractive alternative to tungsten.
Performance analysis of a new network access flow control method in computer communication networks
Authors: Uhl Tadeusz , Müller‐Clostermann Bruno 
Published: September 2008

AbstractA new flow control rule for the network access level is introduced and its performance is investigated., The rule is based on measurements of the temporal changes of the traffic intensity. The admission of arriving local packets to a node is regulated dependent on the variations of local and transit traffic and the load in the neighbouring nodes. The objective of the new rule is to maximize the power (defined as the ratio of throughput and delay) for transit packets under consideration of a threshold value for local packets. This threshold serves to limit the unfairness for the local packets. A model for the node has been developed and evaluated by approximate analytical techniques. The performance results obtained enable the construction of a very efficient algorithm for the new flow control rule.
A mathematical model for the evaluation of spurious response interference in a superheterodyne receiver
Authors: De Franco Giuseppe 
Published: September 2008

AbstractThe Spurious Response phenomenon in a typical superheterodyne receiver, caused by one or more interfering transmitters, is analyzed. Particularly, a suitable model of superheterodyne receiver and the algorithm for the interference level computation is presented. The new approach to the Electromagnetic Interference (EMI) problem, above mentioned, is given by the algorithm for the evaluation of the spurious response rejection parameter: βst. In this way it is possible to evaluate the interference level of a victim receiver without using complex measurement procedures.
BICMOS technologies
Authors: Roche Marcel 
Published: September 2008

AbstractThis paper describes why and how BICMOS technology will be one of the top three technology stars of the next decade. After a presentation of the specific advantages and drawback5 of Bipolar and CMOS technologies, the exploitation of characteristics of both components. realized on the same chip, is discussed. A brief description of BICMOS process architectures is given and the performances currently achieved are presented. Finally present and future applicarions are considered for Memories, Gate arrays, Telecommunications IC's, Analog IC's etc.
Simulation of silicon semiconductor processing
Authors: Pichler Peter , Ryssel Heiner 
Published: September 2008

AbstractIn VLSI development process simulation is needed to understand the interaction between successive process steps and to give input data for device simulation. The goal of this paper is to sketch the present state of process simulation and to give the reader a feeling of the difficulties but also of what can be gained by using such tools. Due to their importance, most attention will be given to the simulation of ion implantation, diffusion, and oxidation.
Three‐dimensional simulation of VLSI structures
Authors: Ciampolini Paolo , Pierantoni Anna , Rudan Massimo , Baccarani Giorgio 
Published: September 2008

AbstractRecent VLSI technologies allow for increasingly small and complex devices, this calling for three‐dimensional device simulation. In this paper, a 3D simulator is presented: the most relevant problems in its development were found in geometry management and computational efficiency. The adoption of suitable linear solvers enhances the overall computational performance, wihile the prism‐based discretization scheme greatly simplifies most of the geometry‐related algorithms, as demonstrated by the proposed examples, in which complex EPROM‐cell structures are easily handled.
Carrier transport modelling in the inversion layer of submicron semiconductor devices
Authors: Sala Cristiano , Magnus Wim , De Meyer Kristin 
Published: September 2008

AbstractState of‐the‐art semiconductor devices are characterized nowadays by dimensions which are well into the submicron range. As a result, the physical models describing carrier transport in these devices need to be modified to be able to account for phenomena such as hot electron or quantum effects, which are intrinsic to this size regime. In this paper we present a formalism which, starting from a self‐consistent solution of Schrodinger's and Poisson's equations in terms. of semi‐analytical wavefunctions, leads to a system of quantum balance equations. It is expected that, as well as supplying a more accurate description of the abovementioned effects, the resulting models will not be computationally expensive and therefore amenable to implementation in a device simulator.
Modeling and control of VLSI circuit yield
Authors: Traversini Renzo , Lisio Aurelio De , Barbuscia Giuseppe 
Published: September 2008

AbstractDue to the increasingly critical role played by yield performance in VLSI device market competition, the development of yield models for product design and production control and improvement is nowadays a very active field of research and development. The overall manufacturing yield can be decomposed in several yield contributions related to different phases of the production process or to different degradation mechanisms. Defect yield losses are related to local device deformations usually due to spot defects and particles. Parametric yield losses are linked 10 global device deformations related to limited control on process conditions. In the paper several state‐of‐the‐art modeling approaches to these yield terms will be presented. Moreover, the issue of yield control and monitoring for each of these loss contributions will be reviewed.
An extended majority‐carrier approach for the DC and small‐signal simulation of ion‐implanted mesfets on compensated and p‐type substrates
Authors: Ghione Giovanni , Benvenuti Augusto , Pirola Marco , Naldi Carlo 
Published: September 2008

AbstractThe paper proposes an extended majority‐carrier dc and ac two‐dimensional physical model for the simulation of ion‐implanted MESFETs on semi‐insulating andp‐type substrates, including the static and dynamic treatment of partly ionized impurity levels. The numerical implementation of the model is discussed, and it is shown how numerical ill‐conditioning problems suggest the implementation of a full two‐carrier model for the simulation of devices with un‐depletedp‐type substrates. A discussion is presented on the interpretation of rate‐dependent anomalies related to the frequency behaviour of the small‐signal parameters, and the importance of simulating a backgate electrode is stressed. Finally, comparisons are given with ac and dc data measured onp‐buried layer Siemens devices.
Modelling of pseudomorphic AlGaAs/GaInAs/AlGaAs layers using selfconsistent approach
Authors: Alamkan Jocelyn , Happy Henri , Cordier Yvon , Cappy Alain 
Published: September 2008

AbstractA study of pseudomorphic layers properties using a selfconsistent approach is presented. The strain effects are taken into account. Sheet carrier density and capacitance voltage characteristics are related to technological layer parameters. Simple expressions of subband energy well suited for CAD are then deduced.