bluuebunny/crossref_metadata_2025 huggingface dataset:
VACUUM ENERGY OF SCHRÖDINGER OPERATORS ON METRIC GRAPHS
Authors: HARRISON JONATHAN M , KIRSTEN KLAUS
Published: July 2012

We present an integral formulation of the vacuum energy of Schrödinger operators on finite metric graphs. Local vertex matching conditions on the graph are classified according to the general scheme of Kostrykin and Schrader. While the vacuum energy of the graph can contain finite ambiguities the Casimir force on a bond with compactly supported potential is well defined. The vacuum energy is determined from the zeta function of the graph Schrödinger operator which is derived from an appropriate secular equation via the argument principle. A quantum graph has an associated probabilistic classical dynamics which is generically both ergodic and mixing. The results therefore present an analytic formulation of the vacuum energy of this quasi-one-dimensional quantum system which is classically chaotic.
THE EULER-HEISENBERG LAGRANGIAN BEYOND ONE LOOP
Authors: HUET IDRISH , DE TRAUBENBERG MICHEL RAUSCH , SCHUBERT CHRISTIAN
Published: July 2012

We review what is presently known about higher loop corrections to the Euler-Heisenberg Lagrangian and its Scalar QED analogue. The use of those corrections as a tool for the study of the properties of the QED perturbation series is outlined. As a further step in a long-term effort to prove or disprove the convergence of the N photon amplitudes in the quenched approximation, we present a parameter integral representation of the three-loop Euler-Heisenberg Lagrangian in 1+1 dimensional QED, obtained in the worldline formalism.
QED PROCESSES IN INTENSE LASER FIELDS
Authors: ILDERTON ANTON
Published: July 2012

Intense laser light at facilities such as the Extreme Light Infrastructure and the European X-ray Free Electron Laser offer new prospects for probing fundamental physics. Here we examine the theory behind QED processes in background fields modelling ultra-strong, short-duration laser pulses. We focus on pair creation via the trident and photon-stimulated mechanisms.
CASIMIR-POLDER POTENTIAL IN THE GEOMETRY OF COSMIC STRING WITH CYLINDRICAL SHELL
Authors: KOTANJYAN A. S. , SAHARIAN A. A. , BARDEGHYAN V. M.
Published: July 2012

Combined effects on the Casimir-Polder potential due to a cosmic string and coaxial metallic cylindrical shell are investigated. For the both regions inside and outside the shell, the potential is decomposed into pure string and shell-induced parts. In a special case of an isotropic polarizability tensor, the Casimir-Polder force in the interior region is attractive with respect to the shell. In the exterior region the force is attractive near the shell and repulsive at large distances from the shell.
THERMAL FLUCTUATIONS IN CASIMIR PISTONS
Authors: LOMNITZ M. , VILLARREAL C.
Published: July 2012

We present analytical and simple expressions to determine the free energy, internal energy, entropy, as well as the pressure acting at the interface of a perfectly conducting rectangular Casimir piston. We show that infrared divergencies linear in temperature become cancelled within the piston configuration, and show a continuous behavior consistent with intuitive expectations.
THEORY OF THE CASIMIR EFFECT FOR GRAPHENE AT FINITE TEMPERATURE
Authors: MARACHEVSKY VALERY N.
Published: July 2012

Theory of the Casimir effect for a flat graphene layer interacting with a parallel flat material is presented in detail. The high-temperature asymptotics of a free energy in a graphene-metal system coincides with a Drude high-temperature asymptotics of the metal-metal system. High-temperature behavior in the graphene-metal system is expected at separations of the order of 100 nm at temperature T = 300 K .
FERMIONIC CONDENSATE AND INDUCED CURRENT IN A CONICAL SPACE WITH A CIRCULAR BOUNDARY AND MAGNETIC FLUX
Authors: SAHARIAN A. A.
Published: July 2012

The fermionic condensate and current density are investigated in a (2 + 1)-dimensional conical spacetime in the presence of a circular boundary and a magnetic flux. On the boundary the fermionic field obeys the MIT bag boundary condition. For irregular modes, we consider a special case of boundary conditions at the cone apex, when the MIT bag boundary condition is imposed at a finite radius, which is then taken to zero. The condensate and current are periodic functions of the magnetic flux with the period equal to the flux quantum. For both exterior and interior regions, the expectation values are decomposed into boundary-free and boundary-induced parts. In the case of a massless field the boundary-free part in the vacuum expectation value of the charge density vanishes, whereas the presence of the boundary induces nonzero charge density. At distances from the boundary larger than the Compton wavelength of the fermion particle, the condensate and current decay exponentially, with the decay rate depending on the opening angle of the cone.
IRREDUCIBLE SCALAR MANY-BODY CASIMIR ENERGIES: THEOREMS AND NUMERICAL STUDIES
Authors: SCHADEN MARTIN
Published: July 2012

We define irreducible N-body spectral functions and Casimir energies and consider a massless scalar quantum field interacting locally by positive potentials with classical objects. Irreducible N-body spectral functions in this case are shown to be conditional probabilities of random walks. The corresponding irreducible contributions to scalar many-body Casimir energies are finite and positive/negative for an odd/even number of objects. The force between any two finite objects separable by a plane is always attractive in this case. Analytical and numerical world-line results for the irreducible four-body Casimir energy of a scalar with Dirichlet boundary conditions on a tic-tac-toe pattern of lines are presented. Numerical results for the irreducible three-body Casimir energy of a massless scalar satisfying Dirichlet boundary conditions on three intersecting lines forming an isosceles triangle are also reported. In both cases the symmetric configuration (square and isosceles triangle) corresponds to the minimal irreducible contribution to the Casimir energy.
ENERGY-MOMENTUM TENSORS WITH WORLDLINE NUMERICS
Authors: SCHÄFER MARCO , HUET IDRISH , GIES HOLGER
Published: July 2012

We apply the worldline formalism and its numerical Monte-Carlo approach to computations of fluctuation induced energy-momentum tensors. For the case of a fluctuating Dirichlet scalar, we derive explicit worldline expressions for the components of the canonical energy-momentum tensor that are straightforwardly accessible to partly analytical and generally numerical evaluation. We present several simple proof-of-principle examples, demonstrating that efficient numerical evaluation is possible at low cost. Our methods can be applied to an investigation of positive-energy conditions.
CASIMIR EFFECTS IN GRAPHENE SYSTEMS: UNEXPECTED POWER LAWS
Authors: SERNELIUS BO E.
Published: July 2012

We present calculations of the zero-temperature Casimir interaction between two freestanding graphene sheets as well as between a graphene sheet and a substrate. Results are given for undoped graphene and for a set of doping levels covering the range of experimentally accessible values. We describe different approaches that can be used to derive the interaction. We point out both the predicted power law for the interaction and the actual distance dependence.
THE AHARONOV-BOHM EFFECT IN SCATTERING OF QUASICLASSICAL PARTICLES
Authors: SITENKO YU. A. , VLASII N. D.
Published: July 2012

Quantum-mechanical scattering of nonrelativistic charged particles by a magnetic vortex of nonzero transverse size is considered. The high-frequency limit of a scattered particle corresponds to the quasiclassical limit, and we show that the scattering Aharonov-Bohm effect persists in the quasiclassical limit owing to the Fraunhofer diffraction in the forward direction. Therefore, the flux of a magnetic vortex serves as a gate for the propagation of quasiclassical particles moving orthogonally to the vortex. The issue of the experimental detection of the Fraunhofer diffraction peak and the scattering Aharonov-Bohm effect is discussed.
Enhancement of Temperature Sensitivity for Metal–Insulator–Semiconductor Temperature Sensors by Using Bi2Mg2/3Nb4/3O7 Film
Authors: Lee Jae-Min , Cho In-Tak , Lee Jong-Ho , Yoon Soon-Gil , Cho Il Hwan
Published: July 2012

Metal–insulator–semiconductor (MIS) type temperature sensors with Bi2Mg2/3Nb4/3O7 (BMNO) film are introduced to improve temperature detecting ability. The current gain of presented sensor is nearly 180 within 7–77 °C which is more than the double amount of current gain in previous work. Dielectric thickness dependency of sensor is also decreased comparing with previous sensor. Temperature detecting mechanisms were analyzed by current and temperature relationship. It was also shown that these sensors were reliable through the temperature cycling test.
InGaP/GaAs Dual-Junction Solar Cell with AlGaAs/GaAs Tunnel Diode Grown on 10° off Misoriented GaAs Substrate
Authors: Yu Hung Wei , Chung Chen Chen , Wang Chin Te , Nguyen Hong Quan , Tran Binh Tinh , Lin Kung Liang , Dee Chang Fu , Majlis Burhanuddin Yeop , Chang Edward Yi
Published: July 2012

InGaP/GaAs dual-junction solar cells with different tunnel diodes (TDs) grown on misoriented GaAs substrates are investigated. It is demonstrated that the solar cells with P++-AlGaAs/N++-GaAs TDs grown on 10° off GaAs substrates not only show a higher external quantum efficiency (EQE) but also generate a higher peak current density (J
peak) at higher concentration ratios (185×) than the solar cells with P++-GaAs/N++-InGaP TDs grown on 6° off GaAs substrates. Furthermore, the cell design with P++-AlGaAs/N++-GaAs TDs grown on 10° off GaAs substrates does not generate a disordered InGaP epitaxial layer during material growth, and thus shows superior current–voltage characteristics.
Very Low Leakage Current of High Band-Gap Al2O3 Stacked on TiO2/InP Metal–Oxide–Semiconductor Capacitor with Sulfur and Hydrogen Treatments
Authors: Yen Chih-Feng , Lee Ming-Kwei
Published: July 2012

High dielectric TiO2 film on InP treated by (NH4)2S shows improved electrical characteristics due to the removal of native oxides. Post-metallization annealing (PMA) can provide hydrogen ions, which effectively passivate defects in TiO2/InP film and interface, further improve electrical characteristics but still with high thermionic emission leakage due to low band-gap TiO2. For high band-gap Al2O3 stacked on PMA-TiO2/S–InP MOS structure with equivalent oxide thickness of 1.8 nm, the leakage current densities can be decreased as low as 1.5×10-8 and 2.2×10-7 A/cm2 at ±2 V, and the interface state density is 3.1×1011 cm-2 eV-1.
200 W Output Power at S-Band in AlGaN/GaN Heterojunction Field Effect Transistors with Field Plates on Si Substrates
Authors: Nakazawa Satoshi , Tsurumi Naohiro , Nishijima Masaaki , Anda Yoshiharu , Ishida Masahiro , Ueda Tetsuzo , Tanaka Tsuyoshi
Published: July 2012

Use of Si substrates for the fabrication of microwave AlGaN/GaN heterojunction field effect transistors (HFETs) has been strongly desired for the low cost fabrication. The performance so far has never been satisfactory in view of the output power and the gain as compared with those on SiC substrates. In this paper, AlGaN/GaN HFETs on Si with high output power of 203 W and high linear gain of 16.9 dB at 2.5 GHz are demonstrated. The HFETs have field plates to reduce the feedback capacitance leading to higher gain, of which a new design of the field plates enables high power as well. The structural design is based on the equivalent circuit model using the device parameters extracted from the small signal RF performances. Here, it is found that shortening the field plate length down to 0.6 µm results in the high output power owing to the stable output impedance for various drain voltage. Note that the conditions of the epitaxial growth are optimized to achieve high current density of 850 mA/mm with both the high mobility and high sheet carrier concentration. The device processing is established so as to achieve the high power operation free from the current collapse. The device can be operated at the drain voltage as high as 50 V, which enables the 200 W output power. The presented AlGaN/GaN HFETs are very promising for various microwave applications including cellular base stations, which would lower the system cost taking advantage of cost-effective Si substrates.
Emission Characteristics of Ca and Mg Atoms in Gas Plasma Induced by the Bombardment of Transversely Excited Atmospheric CO2 Laser at 1 atm
Authors: Khumaeni Ali , Lie Zener Sukra , Lee Yong Inn , Kurihara Kazuyoshi , Kurniawan Koo Hendrik , Fukumoto Ken-ichi , Kagawa Kiichiro , Niki Hideaki
Published: July 2012

To study the mechanism of atomic excitation in gas plasma, a transversely excited atmospheric pressure (TEA) CO2 laser (750 mJ, 200 ns) was focused on a metal subtarget through a hole (2 mm in diameter) produced in a glass slide sample (1.5 mm in thickness); the glass slide sample was placed in close contact with a nickel metal plate, which functions as the metal subtarget. It was demonstrated that a strong gas plasma can be induced in various gases including He, N2, and CO2 and that plasma can be employed as the excitation source for spectrochemical analysis. It has been proved that, in He gas plasma, strong Ca ionic emissions (Ca II 393.3 nm and Ca II 373.7 nm) with a long lifetime can be observed regardless of excitation energy. On the other hand, in N2 and CO2 gases, the emissions are very weak and have a short lifetime. We assumed that, in He gas plasma, He metastable atoms play significant role in excitation. In the case of the Ca atom, the double ionization of Ca (Ca2+) is directly induced when a Ca atom collides with He metastable atoms through the Penning effect. The ion produced then recombines with an electron to produce an ionic excitation state, from which ionic emission is induced. In neutral Ca and Mg emissions, unique emission characteristics were observed in the He gas plasma case, namely, the triplet state is the main product and the singlet state is a minor product. This result can be explained by our proposed model.
Temporally Stable and Continuously Tunable Laser Device Fabricated Using Polymerized Cholesteric Liquid Crystals
Authors: Jeong Mi-Yun , Wu Jeong Weon
Published: July 2012

We realized the fabrication of a temporally stabilized continuously tunable laser device using a UV-curable polymerized dye-doped cholesteric liquid crystal wedge cell. The spatial tuning resolution was less than 1 nm over a 70 nm spectral range. The continuous tuning behavior of the polymerized wedge cholesteric liquid crystal (CLC) cell is due to the fact that the concentration of the pitch gradient matches the helical pitch determined by the cell thickness. After about 1 year had elapsed, the spectral range of continuous laser tuning was nearly maintained in the polymerized CLC wedge cells. This scheme raises the possibility of practical applications of the CLC laser device, which allows for a wide tunability of single-mode laser emissions.
Growth-Temperature Dependence of Wetting Layer Formation in High Density InGaAs/GaAs Quantum Dot Structures Grown by Droplet Epitaxy
Authors: Zuerbig Verena , Bugaew Natalia , Reithmaier Johann Peter , Kozub Michał , Musiał Anna , Sęk Grzegorz , Misiewicz Jan
Published: July 2012

We present a study of the growth-temperature-dependent wetting layer formation in self-assembled InGaAs/GaAs quantum dot structures formed by droplet epitaxy at elevated growth temperatures up to 500 °C. The energies of electron heavy-hole and light-hole transitions of the InGaAs wetting layer is investigated by contactless electroreflectance spectroscopy. A clear indication of a strong growth-temperature influence on the wetting layer morphology is observed. At the lowest growth temperature no wetting layer could be detected at all. The influence of the substrate temperature on structural and optical properties of the dots is also discussed.
De-embedding of On-Chip Inductor at Millimeter-Wave Range
Authors: Zhang Bo , Xiong Yong-Zhong , Wang Lei , Hu Sanming , Li Joshua Le-Wei
Published: July 2012

A full matrix calculation based de-embedding methodology for on-chip inductor de-embedding at millimeter-wave range is presented. In this method, all extrinsic elements are subtracted by frequency-independent method. The influence of coupling effects between interconnections which has significant impacts on self-resonance frequency of inductor is subtracted by a new dummy structure. A comparison of different de-embedding methods of millimeter-wave on-chip inductors is performed up to 110 GHz. As compared with common methods, the result shows that the proposed method has good accuracy at high frequency and suitable for millimeter-wave inductor modeling and circuit design.
Enhancement of Active Layer Characteristics with Solvent Spray Annealing Treatment for Organic Solar Cell
Authors: Kim Kyu-Jin , Bae Jin-Ju , Seo Yoon-Sik , Kang Byoung-Ho , Yeom Se-Hyuk , Kwon Dae-Hyuk , Kang Shin-Won
Published: July 2012

This paper presents an active layer treatment method that is referred to as solvent spray annealing. Spray-deposited organic solar cells were fabricated, and then, solvent spray annealing was performed on the active layer with dichlorobenzene while the substrate was heated at 150 °C. The absorbance and crystallinity of the active layer improved after solvent spray annealing. Further, the spray-deposited organic solar cell treated by solvent spray annealing, in which the fill factor and current density dominantly increased, achieved an efficiency of 1.87%, whereas a pristine sample showed an efficiency of 1.1%.
Fabrication of Vanadium Oxide Thin Films on Fused Quartz Substrates by Metal–Organic Decomposition for Bolometer Detectors
Authors: Son Le Ngoc , Tachiki Takashi , Uchida Takashi
Published: July 2012

Axis-oriented V2O5 thin films were prepared on fused quartz substrates by metal–organic decomposition (MOD). Then these films were reduced to VO
x
thin films by heat treatment at a temperature of 530 °C and a pressure of 1.2 Pa in O2. The obtained VO
x
thin films exhibited an abrupt phase transition with a resistivity change of up to 4 orders of magnitude. These VO
x
films had a high temperature coefficient of resistance (TCR) of up to 4.8%/K at 300 K and these values were over two times higher than those of the films fabricated on SiO2/Si substrates.
Test data generation approach for basis path coverage
Authors: Jiang Shujuan , Zhang Yanmei , Yi Dandan
Published: July 2012

On the basis of determining the feasibility of paths, this paper proposes an evolutionary approach to generating test data for feasible basis path coverage. First, the structure of the program under test is expressed by a control flow graph, and the target paths are encoded into the form of hybrid-coding that efficiently combines the statement label with the outcome of a conditional statement (i.e. T or F). Then, the genetic algorithm is employed to generate test data for multiple paths coverage, and the fitness function of an input data (an individual) takes into account the degree of the execution track matching the target paths. Finally, the proposed approach is applied in several benchmark programs. The experimental results show that the proposed approach cannot only avoid redundant test but also improve the efficiency of test data generation effectively
Muon (g− 2): Experiment and Theory
Authors: Miller James P. , Eduardo de Rafael , Roberts B. Lee , Stöckinger Dominik
Published: July 2012

We review the status of the theoretical and experimental determinations of the muon magnetic moment anomaly, [Formula: see text]. We discuss future experimental efforts, as well as implications for physics beyond the Standard Model that come from past and future experiments.
Electron Spin and Its History
Authors: Commins Eugene D.
Published: July 2012

The history of electron spin is summarized. Topics include the discovery of electron spin, the birth of quantum electrodynamics, the invention of magnetic resonance, the invention of renormalization, the anomalous magnetic moment of the electron in experiment and theory, and searches for the electron electric dipole moment.
The CLIC Study of a Multi-TeV Linear Collider
Authors: Delahaye J.P.
Published: July 2012

This article reviews the status of the CLIC (Compact Linear Collider) study toward feasibility demonstration of a novel and challenging technology that has been specially developed to extend the energy reach of linear colliders into the multi-TeV range so that they will be complementary to the LHC (Large Hadron Collider). A conceptual design report is being prepared; it summarizes the performance of a high-energy facility based on this technology, as well as the results of the research and development carried out to address its feasibility.
Structure and activity of the acid-sensing ion channels
Authors: Sherwood Thomas W. , Frey Erin N. , Askwith Candice C.
Published: July 2012

The acid-sensing ion channels (ASICs) are a family of proton-sensing channels expressed throughout the nervous system. Their activity is linked to a variety of complex behaviors including fear, anxiety, pain, depression, learning, and memory. ASICs have also been implicated in neuronal degeneration accompanying ischemia and multiple sclerosis. As a whole, ASICs represent novel therapeutic targets for several clinically important disorders. An understanding of the correlation between ASIC structure and function will help to elucidate their mechanism of action and identify potential therapeutics that specifically target these ion channels. Despite the seemingly simple nature of proton binding, multiple studies have shown that proton-dependent gating of ASICs is quite complex, leading to activation and desensitization through distinct structural components. This review will focus on the structural aspects of ASIC gating in response to both protons and the newly discovered activators GMQ and MitTx. ASIC modulatory compounds and their action on proton-dependent gating will also be discussed. This review is dedicated to the memory of Dale Benos, who made a substantial contribution to our understanding of ASIC activity.
Activation of Toll-like receptor 3 amplifies mesenchymal stem cell trophic factors and enhances therapeutic potency
Authors: Mastri Michalis , Shah Zaeem , McLaughlin Terence , Greene Christopher J. , Baum Leah , Suzuki Gen , Lee Techung
Published: July 2012

Clinical trials of bone marrow mesenchymal stem cell (MSC) therapy have thus far demonstrated moderate and inconsistent benefits, indicating an urgent need to improve therapeutic efficacy. Although administration of sufficient cells is necessary to achieve maximal therapeutic benefits, documented MSC clinical trials have largely relied on injections of ∼1 × 106 cells/kg, which appears too low to elicit a robust therapeutic response according to published preclinical studies. However, repeated cell passaging necessary for large-scale expansion of MSC causes cellular senescence and reduces stem cell potency. Using the RNA mimetic polyinosinic-polycytidylic acid [poly(I:C)] to engage MSC Toll-like receptor 3 (TLR3), we found that poly(I:C), signaling through multiple mitogen-activated protein kinase pathways, induced therapeutically relevant trophic factors such as interleukin-6-type cytokines, stromal-derived factor 1, hepatocyte growth factor, and vascular endothelial growth factor while slightly inhibiting the proliferation and migration potentials of MSC. At the suboptimal injection dose of 1 × 106 cells/kg, poly(I:C)-treated MSC, but not untreated MSC, effectively stimulated regeneration of the failing hamster heart 1 mo after cell administration. The regenerating heart exhibited increased CD34+/Ki67+ and CD34+/GATA4+ progenitor cells in the presence of decreased inflammatory cells and cytokines. Cardiac functional improvement was associated with a ∼50% reduction in fibrosis, a ∼40% reduction in apoptosis, and a ∼55% increase in angiogenesis, culminating in prominent cardiomyogenesis evidenced by abundant distribution of small myocytes and a ∼90% increase in wall thickening. These functional, histological, and molecular characterizations thus establish the utility of TLR3 engagement for enabling the low-dose MSC therapy that may be translated to more efficacious clinical applications.
Irritable Bowel Syndrome: Methods, Mechanisms, and Pathophysiology. The confluence of increased permeability, inflammation, and pain in irritable bowel syndrome
Authors: Camilleri Michael , Lasch Karen , Zhou Wen
Published: July 2012

Irritable bowel syndrome (IBS) is one of the most common gastrointestinal ailments among those seeking health care for gastrointestinal disorders. Despite its prevalence, IBS pathophysiology is still not completely understood. Continued elucidation of IBS etiological mechanisms will lead to a greater appreciation of possible therapeutic targets. In the past decade, there has been increasing focus on the possible connection between increased intestinal mucosal permeability, inflammation, and visceral hypersensitivity. Increased permeability in subsets of IBS patients has been observed and the possible mechanisms underlying this defect are just beginning to be understood. The objectives of this review are to summarize the role of the healthy intestinal epithelium as a barrier between the lumen and the rest of the body with a focus on tight junctions; to examine the lines of evidence that suggest that different triggers lead to increased intestinal mucosal permeability and disruption of tight junctions in IBS patients; and to explore how this increased permeability may elicit immune responses that affect afferent nerves, resulting in the pain associated with IBS.
Systemic Chemotherapy prior to Cytoreductive Surgery and HIPEC for Carcinomatosis from Appendix Cancer: Impact on Perioperative Outcomes and Short-Term Survival
Authors: Bijelic Lana , Kumar Anjali S. , Stuart O. Anthony , Sugarbaker Paul H.
Published: July 2012

Background and Objectives. Systemic chemotherapy administered prior to cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (HIPEC) for peritoneal mucinous adenocarcinoma of appendiceal origin (PMCA) is associated with a significant rate of histological response. The impact of preoperative systemic chemotherapy (PSC) on intraperitoneal tumor burden, completeness of cytoreduction, and perioperative complications is unknown.Methods. We analyzed prospectively collected data from our HIPEC database. Thirty-four patients with PMCA were prospectively recruited and treated with PSC. Perioperative variables and survival in this group of patients were compared against 24 patients with PMCA who did not receive PSC.Results. Ten of 34 patients (29%) receiving PSC had a complete or near complete histological response. Patients receiving PSC had a lower peritoneal carcinomatosis index, required fewer peritonectomies and visceral resections, and achieved complete cytoreduction more frequently compared to patients with no preoperative chemotherapy. The incidence of perioperative complications and survival were not significantly different between the two groups. However, patients with complete histological response had better overall survival compared to patients without complete response.Conclusions. Preoperative systemic chemotherapy in appendix-originated PMCA is associated with a significant rate of histological response which may reduce the tumor burden, facilitate less aggressive and more complete CRS, and improve short-term survival in patients with a significant histological response.
Antioxidant Capacity of Flavonoids in Hepatic Microsomes Is not Reflected by Antioxidant EffectsIn Vivo
Authors: Duthie Garry , Morrice Philip
Published: July 2012

Flavonoids are polyphenolic compounds with potential antioxidant activity via multiple reduction capacities. Oxidation of cellular lipids has been implicated in many diseases. Consequently, this study has assessed the ability of several dietary flavonoid aglycones to suppress lipid peroxidation of hepatic microsomes derived from rats deficient in the major lipid soluble antioxidant, dα-tocopherol. Antioxidant effectiveness was galangin > quercetin > kaempferol > fisetin > myricetin > morin > catechin > apigenin. However, none of the flavonoids were as effective as dα-tocopherol, particularly at the lowest concentrations used. In addition, there appears to be an important distinction between thein vitroantioxidant effectiveness of flavonoids and their ability to suppress indices of oxidationin vivo. Compared with dα-tocopherol, repletion of vitamin E deficient rats with quercetin, kaempferol, or myricetin did not significantly affect indices of lipid peroxidation and tissue damage. Direct antioxidant effect of flavonoidsin vivowas not apparent probably due to low bioavailability although indirect redox effects through stimulation of the antioxidant response element cannot be excluded.
Polymorphism, Hydrogen Bond Properties, and Vibrational Structure of 1H-Pyrrolo[3,2-h]Quinoline Dimers
Authors: Gorski Alexandr , Gawinkowski Sylwester , Luboradzki Roman , Tkacz Marek , Thummel Randolph P. , Waluk Jacek
Published: July 2012

Two forms of cyclic, doubly hydrogen-bonded dimers are discovered for crystalline 1H-pyrrolo[3,2-h]quinoline, a bifunctional molecule possessing both hydrogen bond donor and acceptor groups. One of the forms is planar, the other is twisted. Analysis of IR and Raman spectra, combined with DFT calculations, allows one to assign the observed vibrations and to single out vibrational transitions which can serve as markers of hydrogen bond formation and dimer structure. Raman spectra measured for samples submitted to high pressure indicate a transition from the planar towards the twisted structure. Formation of intermolecular hydrogen bonds leads to a large increase of the Raman intensity of the NH stretching band: it can be readily observed for the dimer, but is absent in the monomer spectrum.
Mercury Disposition in Suckling Rats: Comparative Assessment Following Parenteral Exposure to Thiomersal and Mercuric Chloride
Authors: Blanuša Maja , Orct Tatjana , Vihnanek Lazarus Maja , Sekovanić Ankica , Piasek Martina
Published: July 2012

Due to the facts that thiomersal-containing vaccine is still in use in many developing countries, and all forms of mercury have recognised neurotoxic, nephrotoxic, and other toxic effects, studies on disposition of ethylmercury and other mercury forms are still justified, especially at young age. Our investigation aimed at comparing mercury distribution and rate of excretion in the early period of life following exposure to either thiomersal (TM) or mercuric chloride (HgCl2) in suckling rats. Three experimental groups were studied: control, TM, and HgCl2, with 12 to18 pups in each. Both forms of mercury were administered subcutaneously in equimolar quantities (0.81 μmol/kg b.w.) three times during the suckling period (on the days of birth 7, 9, and 11) to mimic the vaccination regimen in infants. After the last administration of TM or HgCl2, total mercury retention and excretion was assessed during following six days. In TM-exposed group mercury retention was higher in the brain, enteral excretion was similar, and urinary excretion was much lower compared to HgCl2-exposed sucklings. More research is still needed to elucidate all aspects of toxicokinetics and most harmful neurotoxic potential of various forms of mercury, especially in the earliest period of life.
Measuring Biometric Sample Quality in terms of Biometric Feature Information in Iris Images
Authors: Youmaran R. , Adler A.
Published: July 2012

This paper develops an approach to measure the information content in a biometric feature representation of iris images. In this context, the biometric feature information is calculated using the relative entropy between the intraclass and interclass feature distributions. The collected data is regularized using a Gaussian model of the feature covariances in order to practically measure the biometric information with limited data samples. An example of this method is shown for iris templates processed using Principal‐Component Analysis‐ (PCA‐) and Independent‐Component Analysis‐ (ICA‐) based feature decomposition schemes. From this, the biometric feature information is calculated to be approximately 278 bits for PCA and 288 bits for ICA iris features using Masek′s iris recognition scheme. This value approximately matches previous estimates of iris information content.
Effect of Surface‐Modified Paclitaxel Nanowires on U937 Cells In Vitro: A Novel Drug Delivery Vehicle
Authors: Abumaree Mohamed H. , Al-Suwaidan Salem , Al-Kaysi Rabih O.
Published: July 2012

We have fabricated surface‐modified paclitaxel nanowires (SM‐PNs) with a precise diameter and an average length of 50 μm. The surface of these nanowires is coated with a monolayer of octadecylsiloxane (ODS), which prevents aggregation and enhances dispersivity in aqueous media. This system constitutes a novel drug delivery vehicle based on one‐dimensional (1D) nanostructures with a large drug to vehicle ratio. We assayed the cytotoxicity of different diameter SM‐PNs (200, 80, 35, and 18 nm) with U937 cells and compared their activity to microcrystalline paclitaxel. SM‐PNs reduced U937 cell proliferation in culture followed by cell death. For the same amount of paclitaxel, different diameter SM‐PNs displayed different cytotoxic effect at the same incubation time period. SM‐PNs with 35 nm diameters were the most efficient in completely halting cell proliferation following the first 24 hours of treatment, associated with 42% cell death. SM‐PNs with 18 nm diameters were least effective. These SM‐PNs can be tailored to fit a certain treatment protocol by simply choosing the appropriate diameter.
When Do People Become Adults? The Uruguayan Case
Authors: Melgar Natalia , Rossi Máximo
Published: July 2012

This paper explores the key experiences that Uruguayans consider relevant for becoming an adult in Uruguay. In particular, we assess the linkages between adulthood and income; labor market participation and marital status, among other transitions that have been found to be associated with the attainment of adulthood. With the aim of identifying attitudinal patterns, we use the 2008 International Social Survey Program in Uruguay and estimate ordered probit models to examine the importance individuals assign to a series of hypothetical transitions. We discover that gender, age, and educational level are viewed as critical determinants in the passage to adulthood. Moreover, we find that Uruguay may have a different constellation of beliefs pertaining to adult transitions than has been found in similar studies conducted in the United States.
Effect of the Steam Activation Thermal Treatment on the Microstructure of Continuous TiO2 Fibers
Authors: Zhang Xiangchao , Zhang Shiying , You Yang , Li Yunlong
Published: July 2012

The continuous TiO2 fibers have been synthesized by the sol‐gel method using the polymer of titanate as the precursor solution. The as‐synthesized samples were characterized using XRD, SEM, and HR‐TEM analysis methods. The grain growth kinetics was primarily investigated. The results demonstrated that the average diameters of the fibers were in the range of 20–30 μm, the crystal phase of the synthesized TiO2 fiber was transformed from anasate to rutile, and the crystal size became bigger with increasing the temperature using steam activation. The growth exponent and the constant of growth rate of the rutile crystal phase at 500°C were 4 and 2.55 × 106 nm/h, respectively. The activation energies of crystalline growth during 500°C~700°C and 700°C~800°C were 38.62 kJ/mol and 143.91 kJ/mol, respectively.
A Robust Intelligent Framework for Multiple Response Statistical Optimization Problems Based on Artificial Neural Network and Taguchi Method
Authors: Salmasnia Ali , Bastan Mahdi , Moeini Asghar
Published: July 2012

An important problem encountered in product or process design is the setting of process variables to meet a required specification of quality characteristics (response variables), called a multiple response optimization (MRO) problem. Common optimization approaches often begin with estimating the relationship between the response variable with the process variables. Among these methods, response surface methodology (RSM), due to simplicity, has attracted most attention in recent years. However, in many manufacturing cases, on one hand, the relationship between the response variables with respect to the process variables is far too complex to be efficiently estimated; on the other hand, solving such an optimization problem with accurate techniques is associated with problem. Alternative approach presented in this paper is to use artificial neural network to estimate response functions and meet heuristic algorithms in process optimization. In addition, the proposed approach uses the Taguchi robust parameter design to overcome the common limitation of the existing multiple response approaches, which typically ignore the dispersion effect of the responses. The paper presents a case study to illustrate the effectiveness of the proposed intelligent framework for tackling multiple response optimization problems.
Project-Based Learning to Promote Effective Learning in Biotechnology Courses
Authors: Movahedzadeh Farahnaz , Patwell Ryan , Rieker Jenna E. , Gonzalez Trinidad
Published: July 2012

With enrollment in the fields of science, technology, engineering, and mathematics (STEM) shrinking, teachers are faced with the problem of appealing to a new generation of students without sacrificing educational quality. Evidence has shown that this problem can be reduced with the use of a number of pedagogical strategies of which project-based learning (PBL) is one. PBL addresses the fundamental challenge of increasing students’ motivation, their mastery of course material, and finding applications for what they have learned to apply in various situations. This study demonstrates the benefits of redesigning a standard lab-based molecular biology course to create a more effective learning environment. Using PBL, students who enrolled in Bio-251 at Harold Washington College in Chicago were given the responsibility of cloning a bacterial gene from one species into a new host species. They were then tasked with the expression and purification of the resulting protein for future research purposes at University of Illinois-Chicago, a leading 4-year research institute. With use of the PBL method, students showed improvement in the areas of self-confidence, lab technical skills, and interest in STEM-related fields and, most of all, the students showed a high level of performance and satisfaction.
Antibiotic-Impregnated Bone Grafts in Orthopaedic and Trauma Surgery: A Systematic Review of the Literature
Authors: Anagnostakos Konstantinos , Schröder Katrin
Published: July 2012

There exist several options for local antibiotic therapy in orthopaedic and trauma surgery. Over the past years, the use of antibiotic-impregnated bone grafts (AIBGs) has become a popular procedure in the treatment of bone and joint infections. A major advantage of AIBGs involves the possibility of impregnation of various antibiotics depending on the sensitivity profile of the causative organism, whereas an additional surgery with removal of the antibiotic carrier is not necessary, as in the use of antibiotic-loaded bone cement. However, generalized conclusions cannot be clearly drawn from the existing literature due to differences of bone used, impregnation method, antibiotics, their doses, laboratory circumstances, or clinical indications. The present work reviews the literature regarding this topic and sheds some light onto the choice of bone and antibiotics, manufacturing details, and clinical experience.
Imaging of Scarce Archaeological Remains Using Microwave Tomographic Depictions of Ground Penetrating Radar Data
Authors: Soldovieri Francesco , Utsi Erica , Persico Raffaele , Alani Amir M.
Published: July 2012

The Romano-British site of Barcombe in East Sussex, England, has suffered heavy postdepositional attrition through reuse of the building materials for the effects of ploughing. A detailed GPR survey of the site was carried out in 2001, with results, achieved by usual radar data processing, published in 2002. The current paper reexamines the GPR data using microwave tomography approach, based on a linear inverse scattering model, and a 3D visualization that permits to improve the definition of the villa plan and reexamine the possibility of detecting earlier prehistoric remains.
Endodontic Management of Mandibular Second Molar Fused to a Supernumerary Tooth, Using Spiral Computed Tomography as a Diagnostic Aid: A Case Report
Authors: Rudagi Kavitarani , Rudagi B. M. , Metgud Sandeep , Wagle Rahul
Published: July 2012

Fusion is a developmental anomaly characterized by the union of two adjacent teeth. In this paper we report a rare case of fusion involving permanent mandibular second molar with supernumerary tooth. The rarity with which this entity appears, along with its complex characteristics, often makes it difficult to treat. The use of high-end diagnostic imaging modalities such as spiral computed tomography can help the clinician in making a confirmatory diagnosis and determining the treatment plan before undertaking the actual treatment. In the present case, we have used spiral computed tomography (SCT) for better understanding the complicated root canal morphology of the fused tooth and successful management of this rare case.
Bioaccumulation of Polycyclic Aromatic Hydrocarbons and Mercury in Oysters (Crassostrea rhizophorae) from Two Brazilian Estuarine Zones
Authors: Torres Ronaldo J. , Cesar Augusto , Pereira Camilo D. S. , Choueri Rodrigo B. , Abessa Denis M. S. , do Nascimento Marcos R. L. , Fadini Pedro S. , Mozeto Antonio A.
Published: July 2012

Nowadays, organisms are increasingly being used in biomonitoring to assess bioavailability and bioaccumulation of contaminants. This approach can use both native and transplanted organisms in order to accomplish this task. In Brazil, most of the studies related to bioaccumulation of contaminants in oysters deal with metals. The present work employs this kind of test in Brazilian coastal estuaries (Santos and Paranaguá) to evaluate total mercury and polycyclic aromatic hydrocarbon contamination in sediments and oysters (native and caged Crassostrea rhizophorae). The methodologies employed were based on known USEPA methods. Results have shown a significant contamination in Santos sediments and consequent bioavailability of organisms. Paranaguá sediments presented lower contamination in sediments, but native oysters were able to accumulate total Hg. The experiments done with caged oysters did not show significant bioaccumulation of Hg and PAHs in the Paranaguá site, but proved to be an excellent tool to assess bioavailability in the Santos estuary since they were able to bioaccumulate up to 1,600% of total PAH in the samples from the inner part of this estuary when compared to control organisms. Multivariate statistical analyses employed to these results have separated the sites evaluated and the most contaminated samples from the least contaminated.
Predicted Aerobic Capacity of Asthmatic Children: A Research Study from Clinical Origin
Authors: Lochte Lene
Published: July 2012

Objective. To compare longitudinally PAC of asthmatic children against that of healthy controls during ten months.Methods. Twenty-eight asthmatic children aged 7–15 years and 27 matched controls each performed six submaximal exercise tests on treadmill, which included a test of EIA (exercise-induced asthma). Predicted aerobic capacity (mLO2/min/kg) was calculated. Spirometry and development were measured. Physical activity, medication, and “ever asthma/current asthma” were reported by questionnaire.Results. Predicted aerobic capacity of asthmatics was lower than that of controls (P=0.0015) across observation times and for both groups an important increase in predicted aerobic capacity according to time was observed (P<0.001). FEV1of the asthmatic children was within normal range. The majority (86%) of the asthmatics reported pulmonary symptoms to accompany their physical activity. Physical activity (hours per week) showed important effects for the variation in predicted aerobic capacity at baseline (F=2.28,P=0.061) and at the T4 observation (F=3.03,P=0.027) and the analyses showed important asthma/control group effects at baseline, month four, and month ten. Physical activity of the asthmatics correlated positively with predicted aerobic capacity.Conclusion. The asthmatic children had consistently low PAC when observed across time. Physical activity was positively associated with PAC in the asthmatics.
In Vitro Biocompatibility of Endodontic Sealers Incorporating Antibacterial Nanoparticles
Authors: Abramovitz Itzhak , Beyth Nurit , Weinberg Guy , Borenstein Alon , Polak David , Kesler-Shvero Dana , Houri-Haddad Yael
Published: July 2012

The main cause of endodontic disease is bacteria. Disinfection is presently achieved by cleaning the root canal system prior to obturation. Following setting, root canal filling is devoid of any antibacterial effect. Endodontic sealers with antimicrobial properties yet biocompatible may enhance root canal therapy. For this purpose, quaternized polyethylenimine nanoparticles which are antibacterial polymers, biocompatible, nonvolatile, and stable may be used. The aim of the present study was to examine the impact of added QPEI on the cytotoxicity of AH Plus, Epiphany, and GuttaFlow endodontic sealers. The effect of these sealers on the proliferation of RAW 264.7 macrophage and L‐929 fibroblast cell lines and on the production of TNFα from macrophages was examined. Cell vitality was evaluated using a colorimetric XTT assay. The presence of cytokines was determined by two‐site ELISA. Results show that QPEI at 1% concentration does not impair the basic properties of the examined sealers in both macrophages and fibroblast cell lines. Incorporation of 1% QPEI into the sealers did not impair their biocompatibility. QPEI is a potential clinical candidate to improve antibacterial activity of sealers without increasing cytotoxicity.
Radicular Dens Invaginatus: Report of a Rare Case
Authors: Beena V. T. , Sivakumar R. , Heera R. , Rajeev R. , Choudhary Kanaram , Panda Swagatika
Published: July 2012

Dens invaginatus is a developmental anomaly resulting from invagination of a portion of crown forming within the enamel organ during odontogenesis. The invagination ranges from a slight pitting (coronal type) to an anomaly occupying most of the crown and root (radicular type). Although a clinical examination may reveal a deep fissure or pit on the surface of an anterior tooth, radiographic examination is the most realistic way to diagnose the invagination. The objective of this case presentation is to report a rare case of radicular dens in dente, which is a rare dental anomaly.
Step Soliton Generalized Solutions of the Shallow Water Equations
Authors: Alvarez A. C. , Meril A. , Valiño-Alonso B.
Published: July 2012

Generalized solutions of the shallow water equations are obtained.
One studies the particular case of a generalized soliton function passing by a variable bottom.
We consider a case of discontinuity in bottom depth. We assume that the surface elevation
is given by a step soliton which is defined using generalized solutions (Colombeau 1993).
Finally, a system of functional equations is obtained where the amplitudes and celerity
of wave are the unknown parameters. Numerical results are presented showing that the
generalized solution produces good results having physical sense.