bluuebunny/crossref_metadata_2025 huggingface dataset:
Oscillatory Dynamics of Cdc42 GTPase in the Control of Polarized Growth
Authors: Das Maitreyi , Drake Tyler , Wiley David J. , Buchwald Peter , Vavylonis Dimitrios , Verde Fulvia
Published: May 2012

Pole to Pole

How do fission yeast cells decide when to grow at a single end (or pole) of the cell or whether to grow in a multipolar manner?

Das
et al.

(p.
239
, published online 17 May) found that accumulation of the active form of the small guanine nucleotide–binding protein Cdc42 at the growing tip of the cell oscillated with a period of a few minutes. In cells growing at one pole, the oscillations were primarily present at that pole and during bipolar growth symmetrical anticorrelated oscillations were observed. Dynamic competition for Cdc42 between multiple growth zones could represent a flexible mechanism to modulate cell growth asymmetry.
Evolution and Functional Impact of Rare Coding Variation from Deep Sequencing of Human Exomes
Authors: Tennessen Jacob A. , Bigham Abigail W. , O’Connor Timothy D. , Fu Wenqing , Kenny Eimear E. , Gravel Simon , McGee Sean , Do Ron , Liu Xiaoming , Jun Goo , Kang Hyun Min , Jordan Daniel , Leal Suzanne M. , Gabriel Stacey , Rieder Mark J. , Abecasis Goncalo , Altshuler David , Nickerson Deborah A. , Boerwinkle Eric , Sunyaev Shamil , Bustamante Carlos D. , Bamshad Michael J. , Akey Joshua M. ,   Broad GO,   Seattle GO,   on behalf of the NHLBI Exome Sequencing Project
Published: May 2012

A Deep Look Into Our Genes

Recent debates have focused on the degree of genetic variation and its impact upon health at the genomic level in humans (see the Perspective by

Casals and Bertranpetit

).

Tennessen
et al.

(p.
64
, published online 17 May), looking at all of the protein-coding genes in the human genome, and

Nelson
et al.

(p.
100
, published online 17 May), looking at genes that encode drug targets, address this question through deep sequencing efforts on samples from multiple individuals. The findings suggest that most human variation is rare, not shared between populations, and that rare variants are likely to play a role in human health.
Direct Detection of Projectile Relics from the End of the Lunar Basin–Forming Epoch
Authors: Joy Katherine H. , Zolensky Michael E. , Nagashima Kazuhide , Huss Gary R. , Ross D. Kent , McKay David S. , Kring David A.
Published: May 2012

The Rocks That Hit the Moon

The cratered surface of the Moon bears witness to the numerous impacts it has suffered. Chemical signatures of these impacts have been detected indirectly. Now,

Joy
et al.

(p.
1426
, published online 17 May; see the Perspective by

Rubin

) report the detection and characterization of meteorite fragments preserved in ancient lunar regolith breccias from the Apollo 16 landing site. These meteoritic fragments represent direct samples of the population of small bodies traversing the inner solar system at around 3.4 billion years ago—the same time or just after the basin-forming epoch on the Moon.
Graphene Barristor, a Triode Device with a Gate-Controlled Schottky Barrier
Authors: Yang Heejun , Heo Jinseong , Park Seongjun , Song Hyun Jae , Seo David H. , Byun Kyung-Eun , Kim Philip , Yoo InKyeong , Chung Hyun-Jong , Kim Kinam
Published: May 2012

Updating the Triode with Graphene

In early electronics, the triode—a vacuum device that combined a diode and an electrical grid—was used to control and amplify signals, but was replaced in most applications by solid-state silicon electronics. One characteristic of silicon-metal interfaces is that the Schottky barrier created—which acts as a diode—does not change with the work function of the metal—the Fermi level is pinned by the presence of surface states.

Yang
et al.

(p.
1140
, published online 17 May) now show that for a graphene-silicon interface, Fermi-level pinning can be overcome and a triode-type device with a variable barrier, a “barristor,” can be made and used to create devices such as inverters.
Fragments of the Lunar Cataclysm
Authors: Rubin Alan E.
Published: May 2012

Meteorite samples returned from the Moon may reveal processes involved in the evolution of the early solar system.
Poor professionalism identified through investigation of unsolicited healthcare complaints
Authors: van Mook Walther N K A , Gorter Simone L , Kieboom Wendy , Castermans Miem G T H , de Feijter Jeantine , de Grave Willem S , Zwaveling Jan Harm , Schuwirth Lambert W T , van der Vleuten Cees P M
Published: May 2012

Aim

To determine whether analysis of unsolicited healthcare complaints specifically focusing on unprofessional behaviour can provide additional information from the patients' perspective.

Methods

A qualitative study with content analysis of healthcare complaints and associated judgements using complaints filed from 2004 to 2009 at the complaints committee of a tertiary-referral centre. Subsequent comparison of the resulting categories of poor professionalism to categories perceived relevant by physicians in a previous study was performed.

Results

137 complaints (98%) yielded 46 different unprofessional behaviours grouped into 18 categories. The element ‘perceived medical complications and error’ occurred most commonly (n=77), followed by ‘having to wait for care’ and ‘insufficient or unclear clarification’ (n=52, n=48, respectively). The combined non-cognitive elements of professionalism (especially aspects of communication) were far more prominently discussed than cognitive issues (knowledge/skills) related to medical error. Most categories of professionalism elements were considered important by physicians but, nevertheless, were identified in patient complaints analysis. Some issues (eg, ‘altruism’, ‘appearance’, ‘keeping distance/respecting boundaries with patients’) were not perceived as problematic by patients and/or relatives, while mentioned by physicians. Conversely, eight categories of poor professionalism revealed from complaint analysis (eg, ‘having to wait for care’, ‘lack of continuity of care’ and ‘lack of shared decision making’) were not considered essential by physicians.

Conclusions

The vast majority of unprofessional behaviour identified related to non-cognitive, professionalism aspects of care. Complaints pertaining to unsatisfactory communication were especially noticeable. Incongruence is noted between the physicians' and the patients' perception of actual care.
COSMOLOGICAL MODEL OF INTERACTING TACHYON FIELD
Authors: SHCHIGOLEV V. K. , ROTOVA M. P.
Published: May 2012

In this paper we investigate a tachyon field model in cosmology, provided its interaction with the quintessence or phantom fields. The model takes into account this interaction beyond the usual approach, in which the interaction is phenomenologically described by the energy flow between the matter components. In our model, the interaction of tachyon field with a canonical scalar field is taken into account through the interaction potential in the total Lagrangian of the system, like in the case of two or more canonical scalar fields. We obtain the different types of exact solution for the model by employing the so-called "first order formalism" procedures.
MUTUAL TRANSFORMATION BETWEEN DIFFERENT s-PARAMETRIZED QUANTIZATION SCHEMES BASED ON s-ORDERED WIGNER OPERATOR
Authors: FAN HONG-YI , WANG SHUAI
Published: May 2012

s-parametrized quantization is essential to phase space theory of quantum mechanical. Based on s-ordered Wigner operator, we examine the classical correspondence of the s2-parametrized Wigner operator through the s1-parametrized quantization scheme, and establish the mutual transformation relation between different s-parametrized quantization schemes. It turns out that the s-parametrized Wigner operator's s-ordering is just the Dirac delta function, which seems to be a new result. As applications, we derive the s-ordered form of the density operator of thermal states and some new generating function formula of Hermite polynomials.
GAUGE AND POINCARÉ INVARIANT REGULARIZATION AND HOPF SYMMETRIES
Authors: LIZZI FEDELE , VITALE PATRIZIA
Published: May 2012

We consider the regularization of a gauge quantum field theory following a modification of the Pochinski proof based on the introduction of a cutoff function. We work with a Poincaré invariant deformation of the ordinary pointwise product of fields introduced by Ardalan, Arfaei, Ghasemkhani and Sadooghi, and show that it yields, through a limiting procedure of the cutoff functions, to a regularized theory, preserving all symmetries at every stage. The new gauge symmetry yields a new Hopf algebra with deformed costructures, which is inequivalent to the standard one.
SUPERGROUP BF ACTION FOR SUPERGRAVITY
Authors: RAMIREZ C. , ROSALES E.
Published: May 2012

General relativity can be formulated as a complex BF-theory with constraints, as given by Plebański. We show that a straightforward OSp (2|1) extension of the action requires additional fields with one constraint, and that supergravity with cosmological constant turns out on-shell, after the application of integrability conditions in the action. This action is invariant under Kalb–Ramond transformations which, as in usual BF theories, correspond on-shell to diffeomorphisms.
THE SUPPORT GENERA OF CERTAIN LEGENDRIAN KNOTS
Authors: LI YOULIN , WANG JIAJUN
Published: May 2012

In this paper, the support genera of all Legendrian right-handed trefoil knots and some other Legendrian knots are computed. We give examples of Legendrian knots in the three-sphere with the standard contact structure which have positive support genera with arbitrarily negative Thurston–Bennequin invariant. This answers a question in [S. Onaran, Invariants of Legendrian knots from open book decompositions, Int. Math. Res. Not.10 (2010) 1831–1859].
THE DESIGNS OF ACCEPTANCE SAMPLING FOR STRENGTH DISTRIBUTIONS WITH PERCENTILES
Authors: LIO Y. L. , TSAI TZONG-RU , WU SHUO-JYE
Published: May 2012

In material manufacturing applications, the lower percentiles of breaking strength of products contain critical reliability information. To promote the quality of product, it is important to ensure the lower percentiles of product breaking strength meet a satisfactory level. In this paper, two acceptance sampling plans are developed based on the percentiles of Weibull distribution and lognormal distribution with truncated life testing samples. An algorithm is provided to obtain acceptance sampling plans under the specified points of producer's risk and consumer's risk. Some tables are presented for numerical study, and an example of real data set regarding the first failure times of small electric carts used for internal transportation and delivery is provided for illustration.
RELIABILITY AND AVAILABILITY ANALYSIS OF MECHANICAL SYSTEMS USING STOCHASTIC PETRI NET MODELING BASED ON DECOMPOSITION APPROACH
Authors: KUMAR GIRISH , JAIN VIPUL , GANDHI O. P.
Published: May 2012

Reliability and availability assessment of a complex system in a single model, considering binary states of individual components, using Markov technique is difficult due to state space explosion problem. Inclusion of various types of dependencies in the model further aggravates it. To overcome this, Stochastic Petri net (SPN) modeling based on decomposition is proposed for reliability and availability assessment of mechanical systems. The decomposition is based on three aspects of the system: Hierarchical level, basic structure and dependency. The model is demonstrated at three hierarchical levels. Individual component (level '3') SPN model is developed assuming Weibull failure distribution, while the individual subsystem (level '2') SPN model is developed considering the arrangement of components within the subsystem. The individual model at level '2' is reduced to an equivalent single net model and its equivalent transition rate is derived from its basic structure assuming the independence of components. This along with the dependencies (e.g. repair, standby redundancy) are included in the system model (level '1'). The repair distribution in this model is assumed exponential. Reachable markings are generated for the system model to obtain the reduced state space of Semi-Markov model for assessment of reliability and availability of the system. The steps of the proposed methodology are suggested and these are illustrated for a pumping system, with two pumps; one in standby.
TWO-STAGE DESIGN OF EXPERIMENTS APPROACH FOR PREDICTION OF RELIABILITY OF OPTOCOUPLERS
Authors: THADURI ADITHYA , VERMA A. K. , VINOD GOPIKA , RAJESH M. G. , KUMAR UDAY
Published: May 2012

Conventionally, reliability prediction of electronic components is carried out using standard handbooks such as MIL STD 217 plus, Telcordia, etc. But these methods fail to provide a realistic estimate of reliability for upcoming technologies. Currently, electronic reliability prediction is moving towards applying the Physics of Failure approach which considers information on process, technology, fabrication techniques, materials used, etc. Industries employ different technologies like CMOS, BJT and BICMOS for various applications. The possibility of chance of failure at interdependencies of materials, processes, and characteristics under operating conditions is the major concern which affects the performance of the devices. They are characterized by several failure mechanisms at various stages such as wafer level, interconnection, etc. For this, the dominant failure mechanisms and stress parameters needs to be identified.

Optocouplers are used in input protection of several instrumentation systems providing safety under over-stress conditions. Hence, there is a need to study the reliability and safety aspects of optocouplers. Design of experiments is an efficient and prominent methodology for finding the reliability of the item, as the experiment provides a proof for the hypothesis under consideration. One of the important techniques involved is Taguchi method which is employed for finding the prominent failure mechanisms in semiconductor devices. By physics of failure approach, the factors that are affecting the performance on both environmental and electrical parameters with stress levels for optocouplers are identified. By constructing a 2-stage Taguchi array with these parameters where output parameters decides the effect of top two dominant failure mechanisms and their extent of chance of failure can be predicted. This analysis helps us in making the appropriate modifications considering both the failure mechanisms for the reliability growth of these devices. This paper highlights the application of design of experiments for finding the dominant failure mechanisms towards using physics of failure approach in electronic reliability prediction of optocouplers for application of instrumentation.
VARIABLES QUICK SWITCHING SYSTEM WITH DOUBLE SPECIFICATION LIMITS
Authors: BALAMURALI S. , USHA M.
Published: May 2012

This paper investigates a variables quick switching sampling system when a measurable quality characteristic has double specification limits beyond which an item is considered to be a nonconforming. The quality characteristic of interest is assumed to follow a normal distribution. The optimal parameters of the variables quick switching system are determined for both known and unknown standard deviations which satisfy the producer's and consumer's risks at the corresponding specified quality levels. Symmetric and asymmetric cases based on the fraction nonconforming by the lower and the upper specification limits are also considered. The problem is formulated as a nonlinear programming where the objective function to be minimized is the average sample number and the constraints are related to a lot of acceptance probabilities at acceptable quality level and limiting quality level under the operating characteristic curve.
DESIGN OF THE c AND np CHARTS WHEN THE PARAMETERS ARE ESTIMATED
Authors: CASTAGLIOLA PHILIPPE , WU SHU
Published: May 2012

The performance of attribute control charts is usually evaluated under the assumption of known process parameters (i.e., the nominal proportion of nonconforming units or the nominal number of nonconformities). However, in practice, these process parameters are rarely known and have to be estimated from an in-control historical Phase I data set. In this paper, we investigate the number m of Phase I samples that would be necessary for the c and p charts with estimated parameters in order to obtain similar in-control ARL's as in the known parameters case. We also propose new specific chart parameters that allow the c and np charts with estimated parameters to have approximately the same in-control ARL's as the ones obtained in the known parameter case.
THE SYMMETRIC CROSSCAP NUMBER OF THE GROUPS OF SMALL-ORDER
Authors: ETAYO J. J. , MARTÍNEZ E.
Published: May 2012

Every finite group G acts as an automorphism group of some non-orientable Klein surfaces without boundary. The minimal genus of these surfaces is called the symmetric crosscap number and denoted by [Formula: see text]. It is known that 3 cannot be the symmetric crosscap number of a group. Conversely, it is also known that all integers that do not belong to nine classes modulo 144 are the symmetric crosscap number of some group. Here we obtain infinitely many groups whose symmetric crosscap number belong to each one of six of these classes. This result supports the conjecture that 3 is the unique integer which is not the symmetric crosscap number of a group. On the other hand, there are infinitely many groups with symmetric crosscap number 1 or 2. For g > 2 the number of groups G with [Formula: see text] is finite. The value of [Formula: see text] is known when G belongs to certain families of groups. In particular, if o(G) < 32, [Formula: see text] is known for all except thirteen groups. In this work we obtain it for these groups by means of a one-by-one analysis. Finally we obtain the least genus greater than two for those exceptional groups whose symmetric crosscap number is 1 or 2.
ISOMORPHISM OF QF ALGEBRAS OVER ℚ
Authors: FURUTANI R. , KIKUMASA I. , YOSHIMURA H.
Published: May 2012

We show that the local–global principle (Hasse principle) holds for isomorphisms between commutative local QF algebras over ℚ of dimension five with radical cubed zero, and obtain a criterion for them to be isomorphic by the Hilbert symbol or the Legendre symbol. As a consequence, we give the isomorphism classes of some type of local algebras over ℚ by using a factor group of ℚ*.
SOME RESULTS ON ONE-FIBERED IDEALS
Authors: BEDDANI CHAREF , MESSIRDI WAHIBA
Published: May 2012

The aim of this paper is to prove some results about the one-fibered ideals (i.e. ideals with only one Rees valuation). We will introduce and study the notion of nth roots of this type of ideals and we will present several properties related to its integral closure by using the one-fiberedness criterion of Hübl and Swanson.
THE RATIONAL GROUP ALGEBRA OF A FINITE GROUP
Authors: BAKSHI GURMEET K. , KULKARNI RAVINDRA S. , PASSI INDER BIR S.
Published: May 2012

An explicit expression for the primitive central idempotent of the rational group algebra ℚ[G] of a finite group G associated with any complex irreducible character of G is obtained. A complete set of primitive central idempotents and the Wedderburn decomposition of the rational group algebra of a finite metabelian group is also computed.
ON THE QUATERNARY FORMS x2+y2+2z2+3t2, x2+2y2+2z2+6t2, x2+3y2+3z2+6t2 AND 2x2+3y2+6z2+6t2
Authors: ALACA AYŞE , WILLIAMS KENNETH S.
Published: May 2012

Formulas are proved for the number of representations of a positive integer by each of the four quaternary quadratic forms x2+y2+2z2+3t2, x2+2y2+2z2+6t2, x2+3y2+3z2+6t2 and 2x2+3y2+6z2+6t2. As a consequence of these formulas, each of the four series [Formula: see text] is determined in terms of Ramanujan's theta function.
FACTORING POLYNOMIALS IN THE RING OF FORMAL POWER SERIES OVER ℤ
Authors: BIRMAJER DANIEL , GIL JUAN B. , WEINER MICHAEL
Published: May 2012

We consider polynomials with integer coefficients and discuss their factorization properties in ℤ[[x]], the ring of formal power series over ℤ. We treat polynomials of arbitrary degree and give sufficient conditions for their reducibility as power series. Moreover, if a polynomial is reducible over ℤ[[x]], we provide an explicit factorization algorithm. For polynomials whose constant term is a prime power, our study leads to the discussion of p-adic integers.
CONVOLUTIONS OF RAMANUJAN SUMS AND INTEGRAL CIRCULANT GRAPHS
Authors: LE T. A. , SANDER J. W.
Published: May 2012

There exist several generalizations of the classical Dirichlet convolution, for instance the so-called A-convolutions analyzed by Narkiewicz. We shall connect the concept of A-convolutions satisfying a weak form of regularity and Ramanujan sums with the spectrum of integral circulant graphs. These generalized Cayley graphs, having circulant adjacency matrix and integral eigenvalues, comprise a great amount of arithmetical features. By use of our concept we obtain a multiplicative decomposition of the so-called energy of integral circulant graphs with multiplicative divisor sets. This will be fundamental for the study of open problems, in particular concerning the detection of integral circulant graphs with maximal or minimal energy.
CONGRUENCES CONCERNING JACOBI POLYNOMIALS AND APÉRY-LIKE FORMULAE
Authors: HESSAMI PILEHROOD KH. , HESSAMI PILEHROOD T. , TAURASO R.
Published: May 2012

Let p > 5 be a prime. We prove congruences modulo p3-d for sums of the general form [Formula: see text] and [Formula: see text] with d = 0, 1. We also consider the special case t = (-1)d/16 of the former sum, where the congruences hold modulo p5-d.
INVESTMENT IN FLOOD PROTECTION MEASURES UNDER CLIMATE CHANGE UNCERTAINTY
Authors: DE BRUIN KARIANNE , ANSINK ERIK
Published: May 2012

Recent severe river flooding in Europe has triggered debates among scientists and policy-makers on future projections of flood frequency and the need for adaptive investments, such as flood protection measures. Because there exists uncertainty about the impact of climate change on flood risk, such investments require a careful analysis of expected benefits and costs. The objective of this paper is to show how climate change uncertainty affects the decision to invest in flood protection measures. We develop a model that incorporates flexible timing of investment decisions and scientific uncertainty on the extent of climate change impact. This model allows decision-makers to cope with the uncertain impact of climate change on the frequency and damage of river flood events and minimizes the risk of under- or over-investment. One of the innovative elements of our paper is that we explicitly distinguish between structural and non-structural flood protection measures. Our results show that the effects of uncertainty on the optimal initial investment depends on the cost structure of these measures which has several important implications for flood management policy.
THE COST OF CLIMATE CHANGE MITIGATION POLICY IN EASTERN EUROPE AND FORMER SOVIET UNION
Authors: MASSETTI EMANUELE , TAVONI MASSIMO
Published: May 2012

This paper provides one of the few assessments of the economic implications of climate change policies in the important region of Eastern Europe and post-Soviet states. We use an integrated assessment model to evaluate the consequences of implementing climate policies consistent with the targets proposed by the Major Economies Forum by mid-century. We decompose the economic impacts in terms of domestic abatement costs, of oil trading and of international emission permit trading for a variety of scenarios, and show that these could be substantial for this region. The results point towards innovation and economic diversification as key complementary measures to be implemented in preparation of climate mitigation strategies.
HIGH SPIN TOPOLOGICALLY MASSIVE GRAVITY
Authors: CHEN BIN
Published: May 2012

We study the high spin fields coupled to topologically massive gravity in AdS3, paying special attention to the nature of the theory at the critical point. We propose an action incorporating the high spin AdS3 gravity and the topological Chern-Simons term for high spin fields. We discuss the fluctuation spectrum around the AdS3 vacuum and find that besides the usual massless modes there are local massive modes.
THE EFFECT OF DIFFERENT OBSERVATIONAL DATA IN CONSTRAINING COSMOLOGICAL PARAMETERS
Authors: GONG YUNGUI , GAO QING , ZHU ZONG-HONG
Published: May 2012

We use the SNLS3 compilation of 472 type Ia supernova data, the baryon acoustic oscillation measurement of distance, and the cosmic microwave background radiation data from the seven year Wilkinson Microwave Anisotropy Probe to study the effect of their different combinations on the fittings of cosmological parameters. Neither BAO nor WMAP7 data alone gives good constraint on the equation of state parameter of dark energy, but both WMAP7 data and BAO data help type Ia supernova data break the degeneracies among the model parameters, hence tighten the constraint on the variation of equation of state parameter wa, and WMAP7 data does the job a little better. Although BAO and WMAP7 data provide reasonably good constraints on Ωm and Ωk, it is not able to constrain the dynamics of dark energy, we need SNe Ia data to probe the property of dark energy, especially the variation of the equation of state parameter of dark energy. For the SNLS SNe Ia data, the nuisance parameters α and β are consistent for all different combinations of the above data. Their impacts on the fittings of cosmological parameters are minimal. ΛCDM model is consistent with current observational data.
THERMAL PRODUCTION OF AXINO DARK MATTER
Authors: CHOI KIWOON
Published: May 2012

We discuss certain features of the low energy effective interactions of axion supermultiplet, which are relevant for axino cosmology, and examine the implication to thermal production of axino in the early Universe.
Interface Properties of Al2O3/n-GaN Structures with Inductively Coupled Plasma Etching of GaN Surfaces
Authors: Kim Sungsik , Hori Yujin , Ma Wang-Cheng , Kikuta Daigo , Narita Tetsuo , Iguchi Hiroko , Uesugi Tsutomu , Kachi Tetsu , Hashizume Tamotsu
Published: May 2012

The effects of the Cl2-based inductively coupled plasma (ICP) etching of GaN on the interface properties of Al2O3/GaN structures prepared by atomic layer deposition (ALD) were investigated. We used n-GaN layers grown on freestanding n+-GaN substrates with low dislocation density. The ICP etching caused slight disorder of the chemical bonds at the GaN surface and monolayer-level interface roughness at the Al2O3/GaN interface, resulting in poor capacitance–voltage (C–V) characteristics due to high-density interface states including nitrogen-vacancy (VN) related levels. The postannealing process in N2at 400 °C drastically improved theC–Vcharacteristics, probably owing to the partial recovery of the VN-related defects and the increased ordering of chemical bonds in the GaN surface region.
Structural Analyses of Co- and Mn-Substituted BiFeO3 Polycrystalline Films
Authors: Naganuma Hiroshi , Sone Keita , Bae In-Tae , Miyazaki Takamichi , Miura Jun , Nakajima Takashi , Okamura Soichiro
Published: May 2012

Mn- and Co-BiFeO3 polycrystalline films were prepared by a chemical solution deposition (CSD) method and their structures were investigated by grazing incidence X-ray diffraction (GIXRD) and θ–2θ XRD in conjunction with transmission electron microscopy (TEM). GIXRD measurement revealed that the Mn-BiFeO3 film contains the Bi2Fe4O9 pyrochlore phase, which might be attributed to the low magnetization of the Mn-BiFeO3 film. For the Co-BiFeO3 film, secondary phases were not observed by structural analyses and the composition was almost homogeneous. From the analytic aspect of the structure, the magnetization enhancement in the Co-BiFeO3 films is considered to be associated with Co substitution for Fe in BiFeO3.
Design of Two-Dimensional Low-Dielectric Photonic Crystal and Its Terahertz Waveguide Application
Authors: Kitagawa Jiro , Kodama Mitsuhiro , Kadoya Yutaka
Published: May 2012

We have systematically investigated the band structure of a two-dimensional photonic crystal (PC) made of a low permittivity dielectric. We present design of PCs showing photonic band gaps. Subsequently, we propose a terahertz (THz) low-dielectric PC slab waveguide sandwiched between two parallel metal plates. The THz wave propagation on the device was simulated by a finite-difference time-domain method. Taking into account the THz absorption of dielectric and the finite electrical conductivity of the metal, we estimated the propagation loss of a guided mode on the PC slab waveguide. We obtained lower propagation loss than those of typical THz-transmission-lines.
Spin-Transfer-Torque Driven Magneto-Logic Gates Using Nano Spin-Valve Pillars
Authors: Sanid Chirakkal , Murugesh Subramaniam
Published: May 2012

We propose model magneto-logic NOR and NAND gates using a spin valve pillar, wherein the logical operation is induced by spin-polarized currents which also form the logical inputs. The operation is facilitated by the simultaneous presence of a constant controlling magnetic field. The same spin-valve assembly can also be used as a magnetic memory unit. We identify regions in the parameter space of the system where the logical operations can be effectively performed. The proposed gates retain the non-volatility of a magnetic random access memory (MRAM). We verify the functioning of the gate by numerically simulating its dynamics, governed by the appropriate Landau–Lifshitz–Gilbert equation with the spin-transfer torque term. The flipping time for the logical states is estimated to be within nano seconds.
Characteristics of n-Type Asymmetric Schottky-Barrier Transistors with Silicided Schottky-Barrier Source and Heavily n-Type Doped Channel and Drain
Authors: Lin Zer-Ming , Lin Horng-Chih , Huang Tiao-Yuan
Published: May 2012

In this study, we explore the operation of operation a novel asymmetric Schottky-barrier transistor (ASSBT) through using technology computer aided design (TCAD). The new ASSBT features a silicided Schottky-barrier (SB) source, with the channel and drain made of heavily n-doped silicon. By eliminating the SB drain junction contained in conventional symmetrical-type SB metal–oxide–semiconductor field-effect transistors (MOSFETs), a larger on-state current is achievable. Moreover, combined with the adoption of fully depleted thin-film channel, the off-state leakage current can be efficiently suppressed as well. In addition, we also comprehensively analyze the transport mechanisms dominating in different operational regions of this new ASSBT. A pseudo-subthreshold region that shows worse subthreshold swing (SS) than the subthreshold region is identified. A decrease in channel and/or gate oxide thicknesses can contribute to the improvement of the SS of this region. A modified form of scaling length (λ) is also introduced to describe the impacts of structural parameters and gate configurations on the SS characteristics of this new ASSBT.
Three-Dimensional Reconstruction and Finite Element Modeling Analysis of the Rabbit Optic Nerve Head in Acute High Intraocular Pressure
Authors: Qiu Jianfeng , Qian Xiuqing , Cui Qianqian , Mu Chen , Zhang Kunya , Na Bo , Song Hongfang , Quan Haiying , Liu Zhicheng
Published: May 2012

To construct a three-dimensional (3D) rabbit optic nerve head (ONH) model by optical coherence tomography (OCT) images, demonstrate the effectiveness and validity of the model by comparison with changes in the ONH in vivo acute high intraocular pressure (IOP) of the living rabbit. Stress and deformation field analysis of the 3D rabbit ONH model was performed using the finite element method (FEM). Immediately after saline was perfused into the anterior chamber of the rabbit eye in an acute high IOP experiment, the same rabbit eye was scanned by OCT, the OCT had a scan speed of 27000 A scans per second with 3.0×3.0×2.3 mm3 (horizontal × vertical × axial) range. The changes of the in vivo ONH in OCT images were compared with the results of the FEM analysis, the morphological deformations were in accordance with the tendency predicted using FEM analysis.
Parametric Study on the Physical Action of Steam–Water Mixture Jet: Removal of Photoresist Film from Silicon Wafer Surfaces
Authors: Mashiko Takashi , Sanada Toshiyuki , Nishiyama Itsuo , Horibe Hideo
Published: May 2012

We performed experiments to elucidate the physical action of a steam–water mixture jet, which we have proposed as a promising, environmentally friendly tool for cleaning surfaces. Photoresist-coated silicon wafers were adopted as the target and the jet performance of resist removal was evaluated, with several parameters being varied. We found that the resist-removal performance improves as the thickness or the mechanical strength of the resist film decreases, resist–wafer adhesivity decreases, or jet duration increases. The results imply that the essential part of the resist removal by the jet is a physical process including peel-off, in contrast to the established techniques such as the batch cleaning method utilizing chemical reactions. The results also indicate that the physical impact of the jet can be controlled, which will be a significant advantage in applying the jet as a cleaning technique.
Irritable Bowel Syndrome: Methods, Mechanisms, and Pathophysiology. Methods to assess visceral hypersensitivity in irritable bowel syndrome
Authors: Keszthelyi D. , Troost F. J. , Masclee A. A.
Published: May 2012

Irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder, characterized by recurrent abdominal pain or discomfort in combination with disturbed bowel habits in the absence of identifiable organic cause. Visceral hypersensitivity has emerged as a key hypothesis in explaining the painful symptoms in IBS and has been proposed as a “biological hallmark” for the condition. Current techniques of assessing visceral perception include the computerized barostat using rectal distensions, registering responses induced by sensory stimuli including the flexor reflex and cerebral evoked potentials, as well as brain imaging modalities such as functional magnetic resonance imaging and positron emission tomography. These methods have provided further insight into alterations in pain processing in IBS, although the most optimal method and condition remain to be established. In an attempt to give an overview of these methods, a literature search in the electronic databases PubMed and MEDLINE was executed using the search terms “assessment of visceral pain/visceral nociception/visceral hypersensitivity” and “irritable bowel syndrome.” Both original articles and review articles were considered for data extraction. This review aims to discuss currently used modalities in assessing visceral perception, along with advantages and limitations, and aims also to define future directions for methodological aspects in visceral pain research. Although novel paradigms such as brain imaging and neurophysiological recordings have been introduced in the study of visceral pain, confirmative studies are warranted to establish their robustness and clinical relevance. Therefore, subjective verbal reporting following rectal distension currently remains the best-validated technique in assessing visceral perception in IBS.
Expression of TNFAIP3 in intestinal epithelial cells protects from DSS- but not TNBS-induced colitis
Authors: Rhee Lesley , Murphy Stephen F. , Kolodziej Lauren E. , Grimm Wesley A. , Weber Christopher R. , Lodolce James P. , Chang Jonathan E. , Bartulis Sarah J. , Messer Jeannette S. , Schneider Jeff R. , Paski Shirley , Nero Thomas M. , Boone David L.
Published: May 2012

Intestinal epithelial cells (IEC) maintain gastrointestinal homeostasis by providing a physical and functional barrier between the intestinal lumen and underlying mucosal immune system. The activation of NF-κB and prevention of apoptosis in IEC are required to maintain the intestinal barrier and prevent colitis. How NF-κB activation in IEC prevents colitis is not fully understood. TNFα-induced protein 3 (TNFAIP3) is a NF-κB-induced gene that acts in a negative-feedback loop to inhibit NF-κB activation and also to inhibit apoptosis; therefore, we investigated whether TNFAIP3 expression in the intestinal epithelium impacts susceptibility of mice to colitis. Transgenic mice expressing TNFAIP3 in IEC (villin-TNFAIP3 Tg mice) were exposed to dextran sodium sulfate (DSS) or 2,4,6-trinitrobenzene sulfonic acid (TNBS), and the severity and characteristics of mucosal inflammation and barrier function were compared with wild-type mice. Villin-TNFAIP3 Tg mice were protected from DSS-induced colitis and displayed reduced production of NF-κB-dependent inflammatory cytokines. Villin-TNFAIP3 Tg mice were also protected from DSS-induced increases in intestinal permeability and induction of IEC death. Villin-TNFAIP3 Tg mice were not protected from colitis induced by TNBS. These results indicate that TNFAIP3 expression in IEC prevents colitis involving DSS-induced IEC death, but not colitis driven by T cell-mediated inflammation. As TNFAIP3 inhibits NF-κB activation and IEC death, expression of TNFAIP3 in IEC may provide an avenue to inhibit IEC NF-κB activation without inducing IEC death and inflammation.
Imaging regional PaO2 and gas exchange
Authors: Petersson Johan , Glenny Robb W.
Published: May 2012

Several methods allow regional gas exchange to be inferred from imaging of regional ventilation and perfusion (V/Q) ratios. Each method measures slightly different aspects of gas exchange and has inherent advantages and drawbacks that are reviewed. Single photon emission computed tomography can provide regional measure of ventilation and perfusion from which regional V/Q ratios can be derived. PET methods using inhaled or intravenously administered nitrogen-13 provide imaging of both regional blood flow, shunt, and ventilation. Electric impedance tomography has recently been refined to allow simultaneous measurements of both regional ventilation and blood flow. MRI methods utilizing hyperpolarized helium-3 or xenon-129 are currently being refined and have been used to estimate local PaO2 in both humans and animals. Microsphere methods are included in this review as they provide measurements of regional ventilation and perfusion in animals. One of their advantages is their greater spatial resolution than most imaging methods and the ability to use them as gold standards against which new imaging methods can be tested. In general, the reviewed methods differ in characteristics such as spatial resolution, possibility of repeated measurements, radiation exposure, availability, expensiveness, and their current stage of development.
Imaging lung perfusion
Authors: Hopkins Susan R. , Wielpütz Mark O. , Kauczor Hans-Ulrich
Published: May 2012

From the first measurements of the distribution of pulmonary blood flow using radioactive tracers by West and colleagues ( J Clin Invest 40: 1–12, 1961) allowing gravitational differences in pulmonary blood flow to be described, the imaging of pulmonary blood flow has made considerable progress. The researcher employing modern imaging techniques now has the choice of several techniques, including magnetic resonance imaging (MRI), computerized tomography (CT), positron emission tomography (PET), and single photon emission computed tomography (SPECT). These techniques differ in several important ways: the resolution of the measurement, the type of contrast or tag used to image flow, and the amount of ionizing radiation associated with each measurement. In addition, the techniques vary in what is actually measured, whether it is capillary perfusion such as with PET and SPECT, or larger vessel information in addition to capillary perfusion such as with MRI and CT. Combined, these issues affect quantification and interpretation of data as well as the type of experiments possible using different techniques. The goal of this review is to give an overview of the techniques most commonly in use for physiological experiments along with the issues unique to each technique.
Comparison of various approaches to calculating the optimal hematocrit in vertebrates
Authors: Stark Heiko , Schuster Stefan
Published: May 2012

An interesting problem in hemorheology is to calculate that volume fraction of erythrocytes (hematocrit) that is optimal for transporting a maximum amount of oxygen. If the hematocrit is too low, too few erythrocytes are present to transport oxygen. If it is too high, the blood is very viscous and cannot flow quickly, so that oxygen supply to the tissues is again reduced. These considerations are very important, since oxygen transport is an important factor for physical performance. Here, we derive theoretical optimal values of hematocrit in vertebrates and collect, from the literature, experimentally observed values for 57 animal species. It is an interesting question whether optimal hematocrit theory allows one to calculate hematocrit values that are in agreement with the observed values in various vertebrate species. For this, we first briefly review previous approaches in that theory. Then we check which empirical or theoretically derived formulas describing the dependence of viscosity on concentration in a suspension lead to the best agreement between the theoretical and observed values. We consider both spatially homogeneous and heterogeneous distributions of erythrocytes in the blood and also possible extensions, like the influence of defective erythrocytes and cases where some substances are transported in the plasma. By discussing the results, we critically assess the power and limitations of optimal hematocrit theory. One of our goals is to provide a systematic overview of different approaches in optimal hematocrit theory.
Airway imaging in disease: Gimmick or useful tool?
Authors: Paré Peter D. , Nagano Taishi , Coxson Harvey O.
Published: May 2012

Airway remodeling is an important pathophysiological mechanism in a variety of chronic airway diseases. Historically investigators have had to use invasive techniques such as histological examination of excised tissue to study airway wall structure. The last several years has seen a proliferation of relatively noninvasive techniques to assess the airway branching pattern, wall thickness, and more recently, airway wall tissue components. These methods include computed tomography, magnetic resonance imaging, and optical coherence tomography. These new imaging technologies have become popular because to understand the physiology of lung disease it is important we understand the underlying anatomy. However, these new approaches are not standardized or available in all centers so a review of their validity and clinical utility is appropriate. This review documents how investigators are working hard to correct for inconsistencies between techniques so that they become more accepted and utilized in clinical settings. These new imaging techniques are very likely to play a frontline role in the study of lung disease and will, hopefully, allow clinicians and investigators to better understand disease pathogenesis and to design and assess new therapeutic interventions.
Quadriceps neuromuscular function and self-reported functional ability in knee osteoarthritis
Authors: Berger M. J. , McKenzie C. A. , Chess D. G. , Goela A. , Doherty T. J.
Published: May 2012

The purposes of this study were to determine 1) the relationships of self-reported function scores in patients with knee osteoarthritis (OA) to both maximal isometric torque and to isotonic power at a variety of loads, and 2) the degree to which muscle volume (MV) or voluntary activation (VA) are associated with torque and power measures in this population. Isometric maximal voluntary contraction (MVC) torque and isotonic power [performed at loads corresponding to 10, 20, 30, 40, and 50% MVC, and a minimal load (“Zero Load”)] were measured in 40 participants with knee OA. Functional ability was measured with the Western Ontario and McMaster Osteoarthritis Index (WOMAC) function subscale. MV was determined with magnetic resonance imaging, and VA was measured with the interpolated twitch technique. In general, power measured at lower loads (Zero Load and 10–30% MVC, r2= 0.21–0.28, P < 0.05) predicted a greater proportion of the variance in function than MVC torque ( r2= 0.18, P < 0.05), with power measured at Zero Load showing the strongest association ( r2= 0. 28, P < 0.05). MV was the strongest predictor of MVC torque and power measures in multiple regression models ( r2= 0.42–0.72). VA explained only 6% of the variance in MVC torque and was not significantly associated with power at any load ( P > 0.05). Quadriceps MVC torque and power are associated with self-reported function in knee OA, but muscle power at lower loads is more predictive of function than MVC torque. The variance in MVC torque and power between participants is due predominantly to differences in MV and has little to do with deficits in VA.
Effect of menstrual cycle phase on the ventilatory response to rising body temperature during exercise
Authors: Hayashi Keiji , Kawashima Takayo , Suzuki Yuichi
Published: May 2012

To examine the effect of menstrual cycle on the ventilatory sensitivity to rising body temperature, ten healthy women exercised for ∼60 min on a cycle ergometer at 50% of peak oxygen uptake during the follicular and luteal phases of their cycle. Esophageal temperature, mean skin temperature, mean body temperature, minute ventilation, and tidal volume were all significantly higher at baseline and during exercise in the luteal phase than the follicular phase. On the other hand, end-tidal partial pressure of carbon dioxide was significantly lower during exercise in the luteal phase than the follicular phase. Plotting ventilatory parameters against esophageal temperature revealed there to be no significant menstrual cycle-related differences in the slopes or intercepts of the regression lines, although minute ventilation and tidal volume did significantly differ during exercise with mild hyperthermia. To evaluate the cutaneous vasodilatory response, relative laser-Doppler flowmetry values were plotted against mean body temperature, which revealed that the mean body temperature threshold for cutaneous vasodilation was significantly higher in the luteal phase than the follicular phase, but there were no significant differences in the sensitivity or peak values. These results suggest that the menstrual cycle phase influences the cutaneous vasodilatory response during exercise and the ventilatory response at rest and during exercise with mild hyperthermia, but it does not influence ventilatory responses during exercise with moderate hyperthermia.
Molecular Pathways: Targeting P21-Activated Kinase 1 Signaling in Cancer—Opportunities, Challenges, and Limitations
Authors: Eswaran Jeyanthy , Li Da-Qiang , Shah Anil , Kumar Rakesh
Published: May 2012

The evolution of cancer cells involves deregulation of highly regulated fundamental pathways that are central to normal cellular architecture and functions. p21-activated kinase 1 (PAK1) was initially identified as a downstream effector of the GTPases Rac and Cdc42. Subsequent studies uncovered a variety of new functions for this kinase in growth factor and steroid receptor signaling, cytoskeleton remodeling, cell survival, oncogenic transformation, and gene transcription, largely through systematic discovery of its direct, physiologically relevant substrates. PAK1 is widely upregulated in several human cancers, such as hormone-dependent cancer, and is intimately linked to tumor progression and therapeutic resistance. These exciting developments combined with the kinase-independent role of PAK1-centered phenotypic signaling in cancer cells elevated PAK1 as an attractive drug target. Structural and biochemical studies revealed the precise mechanism of PAK1 activation, offering the possibility to develop PAK1-targeted cancer therapeutic approaches. In addition, emerging reports suggest the potential of PAK1 and its specific phosphorylated substrates as cancer prognostic markers. Here, we summarize recent findings about the PAK1 molecular pathways in human cancer and discuss the current status of PAK1-targeted anticancer therapies. Clin Cancer Res; 18(14); 3743–9. ©2012 AACR.