bluuebunny/crossref_metadata_2025 huggingface dataset:
Comprehensive biomechanical modeling and simulation of the upper body
Authors: Lee Sung-Hee , Sifakis Eftychios , Terzopoulos Demetri
Published: September 2009

We introduce a comprehensive biomechanical model of the human upper body. Our model confronts the combined challenge of modeling and controlling more or less all of the relevant articular bones and muscles, as well as simulating the physics-based deformations of the soft tissues. Its dynamic skeleton comprises 68 bones with 147 jointed degrees of freedom, including those of each vertebra and most of the ribs. To be properly actuated and controlled, the skeletal submodel requires comparable attention to detail with respect to muscle modeling. We incorporate 814 muscles, each of which is modeled as a piecewise uniaxial Hill-type force actuator. To simulate biomechanically-realistic flesh deformations, we also develop a coupled finite element model with the appropriate constitutive behavior, in which are embedded the detailed 3D anatomical geometries of the hard and soft tissues. Finally, we develop an associated physics-based animation controller that computes the muscle activation signals necessary to drive the elaborate musculoskeletal system in accordance with a sequence of target poses specified by an animator.
On centroidal voronoi tessellation—energy smoothness and fast computation
Authors: Liu Yang , Wang Wenping , Lévy Bruno , Sun Feng , Yan Dong-Ming , Lu Lin , Yang Chenglei
Published: September 2009

Centroidal Voronoi tessellation (CVT) is a particular type of Voronoi tessellation that has many applications in computational sciences and engineering, including computer graphics. The prevailing method for computing CVT is Lloyd's method, which has linear convergence and is inefficient in practice. We develop new efficient methods for CVT computation and demonstrate the fast convergence of these methods. Specifically, we show that the CVT energy function has 2nd order smoothness for convex domains with smooth density, as well as in most situations encountered in optimization. Due to the 2nd order smoothness, it is possible to minimize the CVT energy functions using Newton-like optimization methods and expect fast convergence. We propose a quasi-Newton method to compute CVT and demonstrate its faster convergence than Lloyd's method with various numerical examples. It is also significantly faster and more robust than the Lloyd-Newton method, a previous attempt to accelerate CVT. We also demonstrate surface remeshing as a possible application.
Artistic rendering of mountainous terrain
Authors: Bratkova Margarita , Shirley Peter , Thompson William B.
Published: September 2009

Panorama maps are aerial view paintings that depict complex, three-dimensional landscapes in a pleasing and understandable way. Painters and cartographers have developed techniques to create such artistic landscapes for centuries, but the process remains difficult and time-consuming. In this work, we derive principles and heuristics for panorama map creation of mountainous terrain from a perceptual and artistic analysis of two panorama maps of Yellowstone National Park. We then present methods to automatically produce landscape renderings in the visual style of the panorama map. Our algorithms rely on United States Geological Survey (USGS) terrain and classification data. Our surface textures are generated using perceptual metrics and artistic considerations, and use the structural information present in the terrain to guide the automatic placement of image space strokes for natural surfaces such as forests, cliffs, snow, and water.
Toward a perceptual space for gloss
Authors: Wills Josh , Agarwal Sameer , Kriegman David , Belongie Serge
Published: September 2009

We design and implement a comprehensive study of the perception of gloss. This is the largest study of its kind to date, and the first to use real material measurements. In addition, we develop a novel multi-dimensional scaling (MDS) algorithm for analyzing pairwise comparisons. The data from the psychophysics study and the MDS algorithm is used to construct a low dimensional perceptual embedding of these bidirectional reflectance distribution functions (BRDFs). The embedding is validated by correlating it with nine gloss dimensions, fitted parameters of seven analytical BRDF models, and a perceptual parameterization of Ward's model. We also introduce a novel perceptual interpolation scheme that uses the embedding to provide the user with an intuitive interface for navigating the space of gloss and constructing new materials.
Triangulation and embedding using small sets of beacons
Authors: Kleinberg Jon , Slivkins Aleksandrs , Wexler Tom
Published: September 2009

Concurrent with recent theoretical interest in the problem of metric embedding, a growing body of research in the networking community has studied the distance matrix defined by node-to-node latencies in the Internet, resulting in a number of recent approaches that approximately embed this distance matrix into low-dimensional Euclidean space. There is a fundamental distinction, however, between the theoretical approaches to the embedding problem and this recent Internet-related work: in addition to computational limitations, Internet measurement algorithms operate under the constraint that it is only feasible to measure distances for a linear (or near-linear) number of node pairs, and typically in a highly structured way. Indeed, the most common framework for Internet measurements of this type is a
beacon-based approach
one chooses uniformly at random a constant number of nodes (“beacons”) in the network, each node measures its distance to all beacons, and one then has access to only these measurements for the remainder of the algorithm. Moreover, beacon-based algorithms are often designed not for embedding but for the more basic problem of
triangulation
, in which one uses the triangle inequality to infer the distances that have not been measured.

Here we give algorithms with provable performance guarantees for beacon-based triangulation and embedding. We show that in addition to multiplicative error in the distances, performance guarantees for beacon-based algorithms typically must include a notion of
slack
—a certain fraction of all distances may be arbitrarily distorted. For metric spaces of bounded doubling dimension (which have been proposed as a reasonable abstraction of Internet latencies), we show that triangulation-based distance reconstruction with a constant number of beacons can achieve multiplicative error 1 + δ on a 1 − ϵ fraction of distances, for arbitrarily small constants δ and ϵ. For this same class of metric spaces, we give a beacon-based embedding algorithm that achieves constant distortion on a 1 − ϵ fraction of distances; this provides some theoretical justification for the success of the recent Global Network Positioning algorithm of Ng and Zhang [2002], and it forms an interesting contrast with lower bounds showing that it is not possible to embed
all
distances in a doubling metric space with constant distortion. We also give results for other classes of metric spaces, as well as distributed algorithms that require only a sparse set of distances but do not place too much measurement load on any one node.
On lattices, learning with errors, random linear codes, and cryptography
Authors: Regev Oded
Published: September 2009

Our main result is a reduction from worst-case lattice problems such as GapSVP and SIVP to a certain learning problem. This learning problem is a natural extension of the “learning from parity with error” problem to higher moduli. It can also be viewed as the problem of decoding from a random linear code. This, we believe, gives a strong indication that these problems are hard. Our reduction, however, is quantum. Hence, an efficient solution to the learning problem implies a
quantum
algorithm for GapSVP and SIVP. A main open question is whether this reduction can be made classical (i.e., nonquantum).

We also present a (classical) public-key cryptosystem whose security is based on the hardness of the learning problem. By the main result, its security is also based on the worst-case quantum hardness of GapSVP and SIVP. The new cryptosystem is much more efficient than previous lattice-based cryptosystems: the public key is of size Õ(
n
2
) and encrypting a message increases its size by a factor of Õ(
n
) (in previous cryptosystems these values are Õ(
n
4
) and Õ(
n
2
), respectively). In fact, under the assumption that all parties share a random bit string of length Õ(
n
2
), the size of the public key can be reduced to Õ(
n
).
Knowledge Transfer from Virtual Environments
Authors: Boulet Guy
Published: September 2009

Trainees of high-stakes scenarios, such as firefighting drills, pilot training, and search-and-rescue exercises, benefit wildly from simulation technology and virtual environments. The learners can practice their skills more frequently and in a safer environment, and the total cost of maintaining the complex training platforms are usually much lower. Recent developments in 3D technology make virtual training even more attractive in the other sense of the word, too.
Computer-Supported Collaborative Learning: Best Practices and Principles for Instructors
Authors: Entin Eileen B. , Sidman Jason , Neal Gualtieri Lisa
Published: September 2009

[The following is a chapter from the upcoming book Programming for e-Learning Developers, by Jeffrey M. Rhodes (ed.). It is reprinted here with permission from the authors.] The value of peer learning is well known, especially for domains in which people will apply what they learn in collaborative settings, but it is challenging to design courses that effectively incorporate and support peer learning. When learners are co-present in the classroom, it is easier to devise exercises that facilitate peer learning. Currently most training outside of the classroom is self-paced, eliminating peer and instructor contact, due to the perceived cost reduction and the greater ease of implementation. It is a challenge to develop online training that incorporates these rich human interactions while respecting the time constraints under which learners operate, yet it can lead to deeper learning that is more memorable and more easily applicable (Neal and Miller, 2005; Notess and Neal, 2006). This chapter discusses considerations and tradeoffs in designing, developing, and evaluating online training for an instructor and students who are geographically distributed. The discussion will take readers through the development process, starting with analysis of audience and goals, to the challenges in acquiring and adapting course material to the online format, and finally the implementation and evaluation. We focus on considerations involved in supporting active engagement of learners and meaningful and thoughtful learner-learner interactions appropriate to the subject matter (Neal and Miller, 2006).
Role of GTPases in Bacterial Ribosome Assembly
Authors: Britton Robert A.
Published: September 2009

The assembly of the ribosome, a complex molecular machine composed of RNA and protein, is a poorly understood process. Recent work has demonstrated that GTPases are likely to play key roles in the assembly of ribosomes in bacteria and eukaryotes. This review highlights several bacterial ribosome assembly GTPases (RA-GTPases) and discusses possible functions for these proteins in the biogenesis of individual ribosomal subunits and subunit joining. RA-GTPases appear to link various aspects of the cell cycle and metabolism with translation. How these RA-GTPases may coordinate these connections are discussed.
Management of Oxidative Stress in Bacillus
Authors: Zuber Peter
Published: September 2009

The spore-forming bacterium and model prokaryotic genetic system, Bacillus subtilis, is extremely useful in the study of oxidative stress management through proteomic and genome-wide transcriptomic analyses, as well as through detailed structural studies of the regulatory factors that govern the oxidative stress response. The factors that sense oxidants and induce expression of protective activities include the PerR and OhrR proteins, which show acute discrimination for their peroxide stimuli, whereas the general stress control factor, the RNA polymerase σB subunit and the thiol-based sensor Spx, govern the protective response to oxidants under multiple stress conditions. Some specific and some redundant protective mechanisms are mobilized at different stages of the Bacillus developmental cycle to deal with vulnerable cells in stationary-phase conditions and during spore germination and outgrowth. An important unknown is the nature and influence of the low-molecular-weight thiols that mediate the buffering of the redox environment.
Genomics, Genetics, and Cell Biology of Magnetosome Formation
Authors: Jogler Christian , Schüler Dirk
Published: September 2009

Magnetosomes are specialized organelles for magnetic navigation that comprise membrane-enveloped, nano-sized crystals of a magnetic iron mineral; they are formed by a diverse group of magnetotactic bacteria (MTB). The synthesis of magnetosomes involves strict genetic control over intracellular differentiation, biomineralization, and their assembly into highly ordered chains. Physicochemical control over biomineralization is achieved by compartmentalization within vesicles of the magnetosome membrane, which is a phospholipid bilayer associated with a specific set of proteins that have known or suspected functions in vesicle formation, iron transport, control of crystallization, and arrangement of magnetite particles. Magnetosome formation is genetically complex, and relevant genes are predominantly located in several operons within a conserved genomic magnetosome island that has been likely transferred horizontally and subsequently adapted between diverse MTB during evolution. This review summarizes the recent progress in our understanding of magnetobacterial cell biology, genomics, and the genetic control of magnetosome formation and magnetotaxis.
Plant-Growth-Promoting Rhizobacteria
Authors: Lugtenberg Ben , Kamilova Faina
Published: September 2009

Several microbes promote plant growth, and many microbial products that stimulate plant growth have been marketed. In this review we restrict ourselves to bacteria that are derived from and exert this effect on the root. Such bacteria are generally designated as PGPR (plant-growth-promoting rhizobacteria). The beneficial effects of these rhizobacteria on plant growth can be direct or indirect. This review begins with describing the conditions under which bacteria live in the rhizosphere. To exert their beneficial effects, bacteria usually must colonize the root surface efficiently. Therefore, bacterial traits required for root colonization are subsequently described. Finally, several mechanisms by which microbes can act beneficially on plant growth are described. Examples of direct plant growth promotion that are discussed include (a) biofertilization, (b) stimulation of root growth, (c) rhizoremediation, and (d) plant stress control. Mechanisms of biological control by which rhizobacteria can promote plant growth indirectly, i.e., by reducing the level of disease, include antibiosis, induction of systemic resistance, and competition for nutrients and niches.
Characterization of High-k Al2O3 Gate Dielectrics Prepared by Oxidation of Aluminum Thin Films
Authors: Gozzi Giuliano , Christiano Veronica , Da Conceição Sthefane A. , Sonnenberg Victor , Dos Santos Filho Sebastião G.
Published: September 2009

This work describes the formation and characterization of aluminum oxide (Al2O3) prepared by oxidation of aluminum thin films in nitric acid at room temperature followed by annealing at 650oC in N2 or Ar on previously engineered (100) silicon wafer surfaces using different cleaning procedures finished in diluted HF (dHF last) or in a sulfuric peroxide mixture (SPM last). The electrical characterization was performed by measurements of Capacitance X Voltage - CV and Current-Voltage - I-V characteristics. The Al2O3 films presented equivalent thicknesses (EOT) ranging from 2.3 to 4.3nm for different cleaning procedures and annealings of the aluminum oxides. In addition, Al2O3 physical thickness (XRBS »6.0-11.5nm) and Al2O3 permissivity (eAl2O3 » 10.5) were obtained with the aid of Rutherford Back-Scattering (RBS) Spectrometry. Also, it was shown that Al2O3 thin films annealed in ultrapure Argon presented better electrical characteristics (leakage current » 11.5 mA/cm2).
Laser Annealing of Self-Aligned As+ Implants in Contact Windows for Ultrashallow Junction Formation.
Authors: Biasotto Cleber , Gonda Viktor , Nanver Lis K. , Van der Cingel J. , Jovanović V.
Published: September 2009

In the past it has been shown that ultrashallow junctions with minimum lateral dimensions can be made by implanting self-aligned to the contact window and using one-shot excimer laser annealing (ELA) to activate the dopants. Besides the recrystallization of the implanted Si, the final structuring at the contact window perimeter is very important for the ideality of the diode. In this paper this process is has been investigated for 5 keV As+ implanted in windows etched in a thermal/LPCVD oxide layer stack. The window perimeter processing is very critical but tilted implants can be used to increase the junction overlap with the window and good diode characteristics are obtained. The junction depths have been analyzed by secondary ion mass spectrometry (SIMS) and transmission electron microscopy (TEM). A junction of only 15 nm deep with a sheet resistance of 311 Ω/square was obtained for an implantation tilt angle of 45o and laser energy density of 1000 mJ/cm2, whereas the junction depth of 20 nm and sheet resistance of 220 Ω/square was obtained for the tilt of 7o.
Optimization of e-beam Systems for Wafer Defect Inspection and for Die-to-Database Verification
Authors: Kazmiruk Viacheslav V. , Barabanenkov Mikhail Y.
Published: September 2009

Are discussed the factors limiting the facilities of electron optical part of the systems for wafer defect inspection and for geometry verification. Is determined the influence of those factors on the system parameters: throughput, spatial resolution and information quality.
Study of Variations of the Electrospinning Process
Authors: Furlan Rogerio , Arroyo Stefanie V. , Torres Ramon O. , Rosado Joel A. , Da Silva Ana Neilde R.
Published: September 2009

Electrospinning has been considered a straightforward way of producing nano and micro fibers. In this work we are analyzing variations of the conventional electrospinning process to better understand and explore the effect of electrostatic interactions. The variations we are investigating include the insertion of polymer inside the electric field keeping the capillary for polymer injection at a floating potential. In this way we are exploring different mechanisms of charge induction. Also, we are using different setup configurations including: same as electrospinning, parallel macro and micro electrodes. Image analysis reveals the occurrence of instabilities/oscillations of the polymer flow (caused by redistribution of charges) leading to the deposition of fibers and improving polymer flow directionality. Fiber orientation on the substrate can be obtained using parallel macro and micro electrodes.
Electrodeposition of Au-Sn Alloys from a Modified Non-Cyanide Bath
Authors: Cardoso Juliana L. , Dos Santos Filho Sebastião G.
Published: September 2009

This work presents improved Au-Sn baths to obtain a potentiostatically deposited Au-Sn alloys, by preventing bath degradation during the electrochemical process. Au-Sn bath speciation was studied through a program for chemical equilibrium simulation (CHEAQS Pro). The electrochemical reactions were investigated using Cyclic Voltammetry (CV). Rutherford Backscattering Spectroscopy (RBS) was used to determine the deposits composition. The results indicated that the best bath composition was KAuCl4 (5 g l-1), SnCl2×2 H2O (5 g l-1), ammonium citrate (150 g l-1), l-ascorbic acid (7.5 g l-1) and sodium sulfite (60 g l-1) to obtain an alloy with 16 at.% Sn. The best potential was defined as -600 mV, due to the largest thickness obtained.
Comparative Study of MDMO-PPV Thin-Film Transistors Using Thermal SiO2 and PECVD Silicon Oxynitride as Insulator
Authors: Cavallari Marco R. , Albertin Katia F. , Santos Gerson , Ramos Carlos A. , Pereyra Inés , Fonseca Fernando J. , Andrade Adnei M.
Published: September 2009

We demonstrate that PECVD SiOxNy with good dielectric properties can replace SiO2 in Organic Thin-Film Transistors (OTFT) applications. It can be used on ITO-covered glass or even flexible substrates thanks to the low deposition temperatures. Poly [2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) is used as the active layer, due to its wide range of applications such as solar cells, light-emitting diodes and light-emitting transistors. We show also that charge carrier mobility can be at least two times higher for silicon oxynitride on p+-Si substrate than silicon dioxide, ≈ 1.1×10-4 cm2.V-1.s-1, which could be further improved by surface treatments.
Study of a-Si1-XCX: H Thin Films Obtained by PECVD in Temperatures Lower than 250{degree sign}C Aiming Applications in Optics, Thin Films Devices on Polymeric Substrate and MEMS
Authors: Pelegrini Marcus V. , Pereyra Inés
Published: September 2009

In this work high optical gap amorphous Silicon Carbide films (a-SixCx-1:H) are produced, studied and characterized. The films are grown at low temperature by PECVD technique, looking for applications in optical devices, MEMS and thin film electronic devices on polymeric substrates. Properties like chemical bonding, refraction index, optical gap, chemical composition and corrosion resistance to KOH solutions are analyzed through FTIR, Optical absorption and RBS measurements and etching tests in KOH. Also MOS capacitors using these films as gate dielectric are fabricated in order to analyze its electrical properties, aiming to verify the influence of the deposition temperature in the SiC structure.
Ni-P, Ni-B and SiO2 as Materials for Hard Mask in Deep Silicon Etching for MEMS Fabrication using ICP reactor
Authors: Nunes Alcinei M. , Moshkalev Stanislav A. , Fischer Clovis , Jurgen Tatsch Peter , Flacker Alexander
Published: September 2009

Ni-P, Ni-B and SiO2 films were used as hard mask materials in Si etching using a high-density inductively coupled plasma (ICP) reactor for MEMS fabrication. The Ni-P and Ni-B films were deposited using an electroless method, and the SiO2 film was thermally grown in a conventional furnace. Two etching processes were used to characterize the masks. The first uses SF6/Ar gas mixture varying bias power and process time, and the second is a Bosch like process, using C4F8 as a passivation gas. The Ni-P mask showed the highest resistance to etching, being applicable in Si deep etching (>100m); while the SiO2 mask was found to be less resistive, especially under strong ion bombardment (high bias power). The Ni-B mask was found to be highly porous, resulting in formation of micropillars during ecthing, which may be interesting for some apllications such as sensors.
Biomimetics: Learning From Nature To Make Better Sensors
Authors: French Patrick J. , Wicaksono Dedy
Published: September 2009

Nature has been the inspiration in art for centuries. In the 19th Century there were a number of attempts to copy nature and apply the ideas to engineering. Unfortunately, this was often done without understanding the details of operation of the natural systems. In some cases engineering successes were based on natural systems without the inventor realising. In more recent years there has been a more detailed investigation of natural systems with the aim to learn from them and build improved sensors. Once again it is important to learn about the mechanisms and not try to copy directly. This paper will discuss a number of natural systems and how they can be implemented in both sensors and actuators.
Feasibility Study of Analogue and Digital Temperature Sensors in Nanoscale CMOS Technologies
Authors: Geljon Max , Sill Frank , De Lima Monteiro Davies William
Published: September 2009

The downscaling of CMOS technology gives rise to a myriad of nanoscale effects. At the same time, power density and thus heat generation increases. The aim of this paper is to evaluate the feasibility of both analogue and digital temperature sensors in nanoscale CMOS using the Berkeley Predictive Technology Model (BPTM) for 65nm. For the oscillator-based digital sensor presented, a sensitivity of 1.86MHz/{degree sign}C is achieved. The analogue sensor achieves a sensitivity of 1.7mV/{degree sign}C.
Flow-injection Analysis Technique Used to Electrochemically Measure Nitrite through a Gold Working Electrode Modified with 1-2 Diaminobenzene (DAB)
Authors: Almeida Fernando L. , Dos Santos Filho Sebastião G. , Fontes Marcelo B.
Published: September 2009

In the present paper, it is presented nitrite analysis, electrochemically measured, using Flow-injection Analysis (FIA) system. The importance to analyze nitrite is based on its toxicity in high concentration for human and animal's body. Then it is essential to balance the alimentation and medicaments doses to control the nitrite concentration. We are working in the development of an electrochemical planar sensor based silk-screen technology. This have a working electrode covered with 1-2 Diaminobenzene (DAB) that permitted excellent selectivity,reproductively, stability and sensibility in nitrite analysis at 750 mVAg/AgCl potential. We have observed that nitrite response is free of interferences below concentrations of 175 μmol l-1, for interfering of uric acid, ascorbic acid and paracetamol and for nitrite concentrations of 50, 250 and 500 μmol l-1. Finally, we have calculated nitrite sensitivity of about 18.2 μmol l-1 cm-2 using a working electrode with 2.5 mm in diameter.
Design of a Compact CPW Antenna using MTM-MEMS
Authors: Rosas Georgina , Murphy Roberto , Corona Alonso
Published: September 2009

This article presents the design of a novel and compact coplanar antenna using metamaterials (MTM) and MEMS. The antenna is based on coplanar waveguide (CPW) technology; therefore, the signal and ground are in the same plane, presenting lower dielectric losses and high signal integrity. The designed antenna can be tuned in the frequency range from 5.3 to 5.8 GHz by MEMS capacitors for wireless communications systems. The design method for these MTM-MEMS antennas, herein presented, is based on a composite right/left handed transmission line using a mixed approach, considering the circuit model and full-wave simulations. The physical size of the antenna is 1/10*lambda where lambda is the free space wavelength.
PDMS (Polydimethylsiloxane) Microfluidic Chip Molding for Love Wave Biosensor
Authors: Tarbague Hakim , Lachaud Jean-Luc , Destor Serge , Velutini Luc , Pillot Jean-Paul , Bennetau Bernard , Moynet Daniel , Rebière Dominique , Pistre Jacques , Dejous Corinne
Published: September 2009

We present the development of new Polydimethylsiloxane (PDMS) chips, which are coupled with Love acoustic wave sensors to realize a detection cell of bio-organisms in liquid media. Three generations of biocompatible PDMS chips have been developed. Built-in thermistors allow a thermal control ({plus minus}0.05{degree sign}C). Unlike the usual assemblies, this chip is maintained by pressure on the sensor and not bonded welded on its surface. This technique makes it entirely removable and cleanable. Therefore, the surface of the sensor can be functionalised or regenerated. The realization of these chips is quick and inexpensive.
Using Cynthia SOI MOSFET to Improve Voltage Gain of Analog Integrated Circuits
Authors: Oliveira Denis R. , Gimenez Salvador P.
Published: September 2009

Theoretically, the surrounding gate SOI MOSFET presents the best possible control of gate region and consequently the best possible Electrostatic Integrity. Cynthia (circular-section) and Pillar (square-section) surrounding gate SOI MOSFETs are examples of this kind of structure. In this paper is performed a comparative study, by 3D numerical simulations, between Cynthia and Pillar surrounding gate SOI MOSFETs, focusing on analog integrated circuits applications, by studying the transconductance over drain current ratio behavior, regarding the same aspect ratio and bias conditions. Both, conventional and Graded-Channel technologies are regarded in this work. It is shown that Cynthia approach allows a voltage gain improvement of up to approximately 10% and 20% in comparison to Pillar surrounding gate SOI nMOSFET, when biased in weak and moderate inversion regimes, respectively.
Impact of Confinement and Stress on the Subband Parameters in Ultra-Thin Silicon Films
Authors: Sverdlov Viktor A. , Baumgartner Oskar , Windbacher Thomas , Schanovsky Franz , Selberherr Siegfried
Published: September 2009

The subband structure in thin silicon films under stress is rigorously analyzed. Calculations of the effective masses in the subbands show a dependence on shear strain and film thickness simultaneously. Both, the effective masses and the subband splitting determine the transport properties in silicon films. A decrease of the transport effective mass controlled by the shear strain component leads to a mobility enhancement even in ultra-thin silicon films. This increase of mobility and thus drive current combined with the improved channel control makes multi-gate MOSFETs based on thin films preeminent candidates for the 22nm technology node and beyond.
CNTFET Modelling for Electronic Circuit Design
Authors: Marani Roberto , Perri Anna G.
Published: September 2009

In this paper we present a model of Carbon Nanotube Field Effect Transistor (CNTFET) to be used for electronic circuit design. The model, with a classical behaviour (MOSFET-like CNTFET), is based on analytical approximations and parameters extracted from quantum mechanical simulations of the device to avoid the resort to self-consistency. The proposed algorithm has been implemented, considering the contribution to the conduction from the first three sub-bands, and the results have been compared with those of the numerical model online available, showing a relative error less than 5%. In order to demonstrate its versatility, the model has been employed to design basic logic gates.
Stadium Cavity Optical Resonator Fabricated by Focused Ion Beam
Authors: Da Silva Filho Adenir , Barea Luis A. , Vaz Alfredo R. , Frateschi Newton C.
Published: September 2009

We have fabricated micro-disk and micro-stadium optical resonators based on conventional InGaAsP/InP multi-quantum well laser epitaxial structures, using a hybrid process by Focused Ion Beam milling and selective wet chemical etching. Resonators with very smooth walls were obtained allowing the observation of optical modes of the stadia with a 15 nm separation. This modal separation is an evidence of the beating between stadium scar modes.
Phase-Shift Photomask Designed by Scalar Diffraction Theory
Authors: Cirino Giuseppe A. , Mansano Ronaldo D. , Verdonck Patrick , Cescato Lucila , Marega Euclydes , Neto Luiz G.
Published: September 2009

This work describes the design of a phase shift lithographic photomask for operation in proximity printing mode. The design explores the freedom of the diffraction of light by travelling along the distance between the mask plane and the wafer plane. To this end, a phase and amplitude modulation distributions was generated, which have to be used in the fabrication of the proposed photomask. Then a photomask with test structures containing several geometric features was fabricated. It is able to modulate both phase and amplitude of the incoming wavefront during exposure of a wafer. The lithographic image to be patterning must be projected onto the wafer plane, located at a distance of 50 μm behind the mask. The 50 μm gap is a necessary condition to explore the diffraction of light in order to improve the resolution when compared with traditional binary masks in proximity printing mode.
Fabrication and Characterization of GeO2-PbO Optical Waveguides
Authors: Del Cacho Vanessa D. , Kassab Luciana R. , Dos Santos Antonio D. , Siarkowski A. L. , Da Silva D. M. , Morimoto Nilton I.
Published: September 2009

This work presents studies of GeO2-PbO thin films deposited by RF Sputtering for fabrication of rib-waveguide. GeO2-PbO vitreous targets were prepared melting the reagents in alumina crucible. Thin films were deposited at room temperature using pure Ar plasma, at 5 mTorr pressure and RF power of 40 W on substrates of (100) silicon wafers. Rutherford Backscattering Spectroscopy (RBS) analyses were employed for the determination of the chemical elements present in the GeO2-PbO film. Geometry and sidewall of the waveguides were investigated by Scanning Electron Microscopy (SEM). The mode propagation in the waveguide structure of GeO2-PbO thin films was analyzed using an integrated optic simulation software to obtain a monomode propagation.
Superposition of Positive and Negative Contributions to the Photocurrent Spectrum of InAs/InAlGaAs/InP Quantum Dot Infrared Photodetectors
Authors: Gebhard Thomas , Alvarenga Deborah , Pires Mauricio P. , Unterrainer Karl , Guimaraes Paulo Sergio S. , De Souza Patricia L.
Published: September 2009

InAs quantum dot structures grown on InGaAlAs lattice matched to InP were investigated by Fourier Transform Infrared Photocurrent Spectroscopy. The measured spectra shows an interesting anomalous feature for low bias voltage conditions. This feature is attributed to the superposition of two photocurrents with opposite directions. The origin of the observed effect is addressed.
Smart Solar Cluster A Self-reconfigurable Photovoltaic Approach
Authors: Carvalho Ágata , De Lima Monteiro Davies William
Published: September 2009

This paper presents an alternative configuration concept for photovoltaic solar cells, namely a Smart Solar Cluster (SSC), which is a self-reconfigurable cluster of either discrete or integrated cells conveniently connected to photoconductive components. Our basic aim is to assess whether an SSC, based on commercial component specifications, can operate efficiently during the year. The simulation results indicate the most appropriate way to design a system using SSCs. This concept is independent of the materials used for the photocell and for the photoconductor, provided their characteristic curves are known.
Semiconductor Microcavity: An Intrinsic Optical Transistor
Authors: Cotta Eduardo A.
Published: September 2009

Since its first observation, many of the phenomena studied in lasers, such as fluctuations, regenerative pulsations, and optical turbulence, can be observed in passive bistable systems, often under better controlled conditions. Their applications are based on dispersive and temperature switching using OB properties, suggesting possibilities in highspeed all-optical signal processing. Thus we investigate the use of semiconductor microcavities with a GaAs single quantum well of 100Aå with Al0.3Ga0.7As barrier, sandwiched between two DBR mirrors (AlAs/Al0.2Ga0.8As). We describe an anomalous and controllable optical bistable regime where we identify one and two crossing between the upward and downward hysteresis curve. The temporal behavior of the device is discussed were we present a purpose to develop an intrinsic optical transistor.
Influence of Fin Width and Channel Length on the Performance of Buffers Implemented with Standard and Strained Triple-Gate nFinFETs
Authors: Pavanello Marcelo A. , Martino João A. , Simoen Eddy , Rooyackers Rita , Collaert Nadine , Claeys Cor
Published: September 2009

In this work the application of standard and strained triple-gate FinFETs in unity-gain source-follower configuration is compared. The analysis is performed by evaluating the buffer voltage gain with respect to the fin width and channel length as well as the total harmonic distortion. It is demonstrated that the application of strained material in narrow FinFETs, when the devices are operating in double-gate mode, can be beneficial for the performance of buffers in any channel length. On the other hand, for triple-gate FinFETs or quasi-planar ones the degradation of the output conductance overcomes the transconductance improvements from strained material and the performance of standard buffers is better than of strained ones. Narrow strained buffers also offer better harmonic distortion.
Fin Width Influence on The Harmonic Distortion of Standard and Strained FinFETs Operating in Saturation
Authors: Doria Rodrigo T. , Cerdeira Antonio , Martino João A. , Simoen Eddy , Claeys Cor , Pavanello Marcelo A.
Published: September 2009

This work compares the harmonic distortion of standard and biaxially strained FinFETs aiming at analog applications such as amplifiers. The harmonic distortion has been extracted for devices operating as single transistor amplifiers. Total harmonic distortion (THD) and third order harmonic distortion (HD3) have been evaluated for devices with several fin widths. For a fairer analysis, the influence of the open-loop voltage gain (Av) in devices with different dimensions has also been considered generating the figures of merit THD/Av and HD3/Av. According to the analysis, narrower devices have overcome the wider ones and conventional FinFETs have shown to be more attractive than the strained ones for analog purposes. Narrower standard FinFETs exhibited up to 20 dB THD/Av better in relation to the strained ones.
Blood glucose monitoring as a teaching tool for endocrinology: a new perspective
Authors: Moats Robert K.
Published: September 2009

The education of new allied health professionals and nurses in proper endocrine evaluation and care has become critical in recent years, especially considering the greatly increased prevalence of diabetes in adults and children. The evaluation of blood glucose levels in human volunteers over time is a powerful teaching tool for endocrinology that has the added benefit of exposing the student to the most fundamental task in diabetes management. The classic procedure involving the ingestion of sucrose followed by blood glucose monitoring was used here to teach the concepts of nonhormonal control of hormone release and blood glucose homeostasis. In addition, a number of volunteers did not ingest a sucrose solution but merely held it in their mouths and expectorated. This so-called “spit” technique has been successfully used to induce the cephalic phase of insulin release (CPIR), an example of neural control of hormone release. As expected, volunteers who ingested sucrose displayed a 38.5% increase in blood glucose 20 min postingestion and a concomitant decrease in blood glucose to near baseline by 60 min postingestion. Those volunteers who did not ingest the sucrose solution displayed a 12.9% reduction in blood glucose levels by 40 min postcompletion, suggestive of the CPIR, followed by a gradual increase in blood glucose levels to near baseline by 60 min postcompletion. The addition of the “spit” technique to this revised protocol of the evaluation of blood glucose exposes the student to the neural control of hormone release and a second example of energy homeostasis.
A simulation for teaching the basic and clinical science of fluid therapy
Authors: Rawson Richard E. , Dispensa Marilyn E. , Goldstein Richard E. , Nicholson Kimberley W. , Vidal Noni Korf
Published: September 2009

The course “Management of Fluid and Electrolyte Disorders” is an applied physiology course taught using lectures and paper-based cases. The course approaches fluid therapy from both basic science and clinical perspectives. While paper cases provide a basis for application of basic science concepts, they lack key components of genuine clinical cases that, by nature, are diverse, change over time, and respond in unique ways to therapeutic interventions. We developed a dynamic model using STELLA software that simulates normal and abnormal fluid and electrolyte balance in the dog. Students interact, not with the underlying model, but with a user interface that provides sufficient data (skin turgor, chemistry panel, etc.) for the clinical assessment of patients and an opportunity for treatment. Students administer fluids and supplements, and the model responds in “real time,” requiring regular reassessment and, potentially, adaptation of the treatment strategy. The level of success is determined by clinical outcome, including improvement, deterioration, or death. We expected that the simulated cases could be used to teach both the clinical and basic science of fluid therapy. The simulation provides exposure to a realistic clinical environment, and students tend to focus on this aspect of the simulation while, for the most part, ignoring an exploration of the underlying physiological basis for patient responses. We discuss how the instructor's expertise can provide sufficient support, feedback, and scaffolding so that students can extract maximum understanding of the basic science in the context of assessing and treating at the clinical level.
Unifying concepts in stimulus-secretion coupling in endocrine cells and some implications for therapeutics
Authors: Misler Stanley
Published: September 2009

Stimulus-secretion coupling (SSC) in endocrine cells remains underappreciated as a subject for the study/teaching of general physiology. In the present article, we review key new electrophysiological, electrochemical, and fluorescence optical techniques for the study of exocytosis in single cells that have made this a fertile area for recent research. Based on findings using these techniques, we developed a model of SSC for adrenal chromaffin cells that blends features of Ca2+entry-dependent SSC (characteristic of neurons) with G protein receptor-coupled, Ca2+release-dependent, and second messenger-dependent SSC (characteristic of epithelial exocrine cells and nucleated blood cells). This model requires two distinct pools of secretory graunules with differing Ca2+sensitivities. We extended this model to account for SSC in a wide variety of peripheral and hypothalamic/pituitary-based endocrine cells. These include osmosensitive magnocellular neurosecretory cells releasing antidiuretic hormone, stretch-sensitive atrial myocytes secreting atrial natriuretic peptide, K+-sensitive adrenal glomerulosa cells secreting aldosterone, Ca2+-sensitive parathyroid chief cells secreting parathyroid hormone, and glucose-sensitive β- and α-cells of pancreatic islets secreting insulin and glucagon, respectively. We conclude this article with implications of this approach for pathophysiology and therapeutics, including defects in chief cell Ca2+sensitivity, resulting in the hyperparathyroidism of renal disease, and defects in biphasic insulin secretion, resulting in diabetes mellitus.
IL-6 stimulates system A amino acid transporter activity in trophoblast cells through STAT3 and increased expression of SNAT2
Authors: Jones H. N. , Jansson T. , Powell T. L.
Published: September 2009

Changes in placental nutrient transport are closely associated with abnormal fetal growth. However, the molecular mechanisms underlying the regulation of placental amino acid transporters are unknown. We demonstrate that physiological concentrations of the proinflammatory cytokines interleukin (IL)-6 and tumor necrosis factor (TNF)-α stimulate the activity of amino acid transporter system A, but not system L, in cultured human primary trophoblast cells. Both cytokines increased the gene and protein expression of the Na+-coupled neutral amino acid transporter (SNAT)2 isoform and upregulated SNAT1 protein expression. IL-6 increased Tyr705 phosphorylation of signal transducer and activator of transcription 3 (STAT3). In cells transfected with small interfering RNA (siRNA) targeting STAT3, the RNA and protein expression of SNAT2, but not SNAT1, was reduced and the stimulating effect of IL-6 on system A activity was abolished. Despite eliciting similar responses in amino acid transport activity and transporter expression, TNF-α effects on system A activity were not mediated through the JAK/STAT pathway. In conclusion, we have identified a novel regulatory pathway involving increased gene expression of the SNAT2 isoform mediated by a STAT-dependent pathway, which links IL-6 to increased activity of system A, a ubiquitously expressed transporter of neutral amino acids. From these new findings, we propose that upregulation of amino acid transporters by cytokines may contribute to increased placental nutrient transport and fetal overgrowth, which are commonly found in pregnancies complicated by maternal diabetes and obesity.
Short-term prednisone use antagonizes insulin's anabolic effect on muscle protein and glucose metabolism in young healthy people
Authors: Short Kevin R. , Bigelow Maureen L. , Nair K. Sreekumaran
Published: September 2009

Glucocorticoids cause muscle atrophy and weakness, but the mechanisms for these effects are unclear. The purpose of this study was to test a hypothesis that prednisone (Pred) counteracts insulin's anabolic effects on muscle. A randomized, double-blind cross-over design was used to test the effects of 6 days either Pred (0.8 mg·kg−1·day−1) or placebo use in seven healthy young volunteers. Protein dynamics were measured across the leg using stable isotope tracers of leucine (Leu) and phenylalanine (Phe) after overnight fast and during a hyperinsulinemic (1.5 μU·min−1·kg FFM−1) euglycemic clamp with amino acid replacement. Fasting glucose, amino acids, insulin, and glucagon were higher ( P < 0.01) on Pred vs. placebo, whereas leg blood flow was 18% lower. However, basal whole body and leg kinetics of Leu and Phe were unaltered by Pred. Insulin infusion increased leg glucose uptake in both trials but was 65% lower with Pred than with placebo. Insulin in both trials similarly suppressed whole body flux of Leu and Phe. Importantly, insulin increased net Leu and Phe balance across the leg and the balance between muscle protein synthesis and breakdown, but these changes were 45–140% lower ( P < 0.03) in Pred than in placebo. The present study demonstrates that short-term Pred use in healthy people does not alter whole body or leg muscle protein metabolism during the postaborptive state but causes muscle insulin resistance for both glucose and amino acid metabolism, with a blunted protein anabolism. This interactive effect may lead to muscle atrophy with continued use of glucocorticoids.
Differential adipokine response in genetically predisposed lean and obese rats during inflammation: a role in modulating experimental colitis?
Authors: Hyland Niall P. , Chambers Adam P. , Keenan Catherine M. , Pittman Quentin J. , Sharkey Keith A.
Published: September 2009

The relationship between a predisposition to obesity and the development of colitis is not well understood. Our aim was to characterize the adipokine response and the extent of colitis in diet-induced obese (DIO) rats. DIO and control, diet-resistant (DR) animals were administered either saline or trinitrobenzene sulfonic acid (TNBS) to induce colitis. Macroscopic damage scores and myeloperoxidase (MPO) activity were measured to determine the extent of inflammation. Trunk blood was collected for the analysis of plasminogen activator inhibitor-1 (PAI-1) as well as leptin, ghrelin, and adiponectin. Colonic epithelial physiology was assessed using Ussing chambers. DIO rats had a modestly increased circulating PAI-1 before TNBS treatment; however, during colitis, DR animals had more than a fourfold increase in circulating PAI-1 compared with DIO rats. Circulating leptin was higher in DIO rats compared with DR animals, in the inflamed and noninflamed states. These changes in TNBS-induced adipokine profile were accompanied by decreased macroscopic tissue damage score in DIO animals compared with DR tissues. Furthermore, TNBS-treated DR animals lost significantly more weight than DIO rats during active inflammation. Colonic epithelial physiology was comparable between groups, as was MPO activity. The factors contributing to the decreased colonic damage are almost certainly multifold, driven by both genetic and environmental factors, of which adipokines are likely to play a part given the increasing body of evidence for their role in modulating intestinal inflammation.