bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermo‐oxidative degradation of HDPE as a function of its crystalline content
Authors: Avalos‐Belmontes Felipe , Zapata‐Gonzalez Ivan , Ramos‐De Valle Luis F. , Zitzumbo‐Guzman Roberto , Alonso‐Romero Sergio
Published: August 2009

The composition, the thermal properties, and the kinetics of the thermo‐oxidative degradation of high‐density polyethylene (HDPE) were studied as a function of the increasing crystalline fraction, which resulted from the selective extraction of the amorphous part, through digestion by immersion in fuming nitric acid (HNO3) for different periods of time. The chemical and thermodynamic changes in HDPE, brought about by digestion in nitric acid for different periods of time, are discussed. Changes in the chemistry and microstructure of the HDPE, as a function of acid treatment for different periods of time, were studied using infra‐red spectroscopy (FTIR), gel permeation chromatography (GPC), and thermal analysis (DSC and TGA), as well as scanning electron microscopy (SEM). These studies were carried out as a function of the extracted amorphous fraction of HDPE samples via digestion in HNO3. These studies showed that in the first stages of the acid chemical attack, the amorphous part first undergoes a chemical modification and then dissolves into the strong acid medium. The total crystalline fraction apparently decreases during the first stages of the chemical attack and then increases as the amorphous part is extracted. TGA results show that as the selective extraction of the amorphous part occurs, there is a displacement of the thermo‐oxidative degradation toward higher temperatures. The kinetics of the thermo‐oxidative degradation as a function of the extraction of the amorphous part was followed according to the Horowitz‐Metzger method, and it was found that as the concentration of the crystalline fraction increases, the activation energy for the thermo‐oxidative degradation increases. SEM studies show that the extraction of the amorphous part does not affect the size of the crystalline lamellar thickness of HDPE. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1906–1915, 2009
Noncovalent functionalization of multiwalled and double‐walled carbon nanotubes: Positive effect of the filler functionalization on high glass transition temperature epoxy resins
Authors: Prado L. A. S. de A. , De La Vega A. , Sumfleth J. , Schulte K.
Published: August 2009

Double‐walled carbon nanotubes (DWCNTs) and multiwalled carbon nanotubes (MWCNTs) were modified using melamine to attach NH2 to the surface of these fillers, without previous oxidation of their graphene layers. FT‐Raman, elemental (chemical) and thermogravimetric analysis, confirmed the modification, which was more extensive for DWCNTs. The potential of this modification was evaluated by adding the melamin‐modified nanotubes to thermosets based on diglycidyl ether of bisphenol A (resin) and polycyclic amine (hardener). Broadening of the glass transition interval and an increase between 7 and 8 °C of the glass transition temperatures show better filler/matrix interaction for the nanocomposites based on melamine‐modified nanotubes. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1860–1868, 2009
Effect of postcasting heat‐treatment on the structure and properties of semicrystalline phase‐inversion poly(vinylidene fluoride) membranes
Authors: Lin Dar‐Jong , Chang Hsu‐Hsien , Beltsios Konstantinos , Don Trong‐Ming , Jeng Yi‐Su , Cheng Liao‐Ping
Published: August 2009

Microporous PVDF membranes were prepared by immersion‐precipitation in 1‐octanol of casting dopes dissolved at different temperatures, with dissolution temperature affecting strongly the membrane microstructure. The effect of postcoagulation thermal annealing, which is an additional thermal parameter, on membrane microstructure and properties is probed herein. Membranes obtained were annealed at temperatures up to 160 °C, which is close to the melting point of PVDF polymer. Annealing leads to a substantial modification of the nano‐scale fine structure of the membranes, while the overall‐microporous structure is preserved. At elevated annealing temperatures, nano‐grains, fibrils, and stick‐like crystalline entities gradually eclipse, while globules develop more robust connections based on wide bands of crystal elements. Probing by X‐ray diffraction and dynamic scanning calorimetry shows that crystallinity increases when annealing temperature and time are increased. As regards mechanical properties, the tensile strength of the membranes can be enhanced substantially, up to about 10 times, upon appropriate high temperature prolonged annealing. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1880–1893, 2009
Nylon‐6 nanocomposites, study of the influence of the nanofiller nature on morphology and material properties
Authors: Tabuani Daniela , Ceccia Simona , Camino Giovanni
Published: August 2009

In this article we investigated the influence of various nanofilllers' aspect ratio, chemical nature, and organic modification on some selected nylon‐6 properties, such as crystallinity, thermal and mechanical resistance, and fire behavior. Materials were prepared by twin‐screw extrusion and characterized by means of scanning and transmission electron microscopy, X‐ray diffraction, thermogravimetric analysis, tensile tests, and cone calorimeter. Fillers characteristics were found to influence at different extents the material final properties. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1935–1948, 2009
Temperature and urea induced denaturation of the TRP‐cage mini protein TC5b: A simulation study consistent with experimental observations
Authors: Gattin Z. , Riniker S. , Hore P. J. , Mok K. H. , van Gunsteren W. F.
Published: August 2009

The effects of temperature and urea denaturation (6M urea) on the dominant structures of the 20‐residue Trp‐cage mini‐protein TC5b are investigated by molecular dynamics simulations of the protein at different temperatures in aqueous and in 6M urea solution using explicit solvent degrees of freedom and the GROMOS force‐field parameter set 45A3. In aqueous solution at 278 K, TC5b is stable throughout the 20 ns of MD simulation and the trajectory structures largely agree with the NMR‐NOE atom–atom distance data available. Raising the temperature to 360 K and to 400 K, the protein denatures within 22 ns and 3 ns, showing that the denaturation temperature is well below 360 K using the GROMOS force field. This is 40–90 K lower than the denaturation temperatures observed in simulations using other much used protein force fields. As the experimental denaturation temperature is about 315 K, the GROMOS force field appears not to overstabilize TC5b, as other force fields and the use of continuum solvation models seem to do. This feature may directly stem from the GROMOS force‐field parameter calibration protocol, which primarily involves reproduction of condensed phase thermodynamic quantities such as energies, densities, and solvation free energies of small compounds representative for protein fragments. By adding 6M urea to the solution, the onset of denaturation is observed in the simulation, but is too slow to observe a particular side‐chain side‐chain contact (Trp6‐Ile4) that was experimentally observed to be characteristic for the denatured state. Interestingly, using temperature denaturation, the process is accelerated and the experimental data are reproduced.
Crystal structure of a trimeric form of the KV7.1 (KCNQ1) A‐domain tail coiled‐coil reveals structural plasticity and context dependent changes in a putative coiled‐coil trimerization motif
Authors: Xu Qiang , Minor Daniel L.
Published: August 2009

Coiled‐coils are widespread protein–protein interaction motifs typified by the heptad repeat (abcdefg)n in which “a” and “d” positions are hydrophobic residues. Although identification of likely coiled‐coil sequences is robust, prediction of strand order remains elusive. We present the X‐ray crystal structure of a short form (residues 583–611), “Q1‐short,” of the coiled‐coil assembly specificity domain from the voltage‐gated potassium channel Kv7.1 (KCNQ1) determined at 1.7 Å resolution. Q1‐short lacks one and half heptads present in a previously studied tetrameric coiled‐coil construct, Kv7.1 585–621, “Q1‐long.” Surprisingly, Q1‐short crystallizes as a trimer. In solution, Q1‐short self‐assembles more poorly than Q1‐long and depends on an R‐h‐x‐x‐h‐E motif common to trimeric coiled‐coils. Addition of native sequences that include “a” and “d” positions C‐terminal to Q1‐short overrides the R‐h‐x‐x‐h‐E motif influence and changes assembly state from a weakly associated trimer to a strongly associated tetramer. These data provide a striking example of a naturally occurring amino sequence that exhibits context‐dependent folding into different oligomerization states, a three‐stranded versus a four‐stranded coiled‐coil. The results emphasize the degenerate nature of coiled‐coil energy landscapes in which small changes can have drastic effects on oligomerization. Discovery of these properties in an ion channel assembly domain and prevalence of the R‐h‐x‐x‐h‐E motif in coiled‐coil assembly domains of a number of different channels that are thought to function as tetrameric assemblies raises the possibility that such sequence features may be important for facilitating the assembly of intermediates en route to the final native state.
Computational design of Candida boidinii xylose reductase for altered cofactor specificity
Authors: Khoury George A. , Fazelinia Hossein , Chin Jonathan W. , Pantazes Robert J. , Cirino Patrick C. , Maranas Costas D.
Published: August 2009

In this study we introduce a computationally‐driven enzyme redesign workflow for altering cofactor specificity from NADPH to NADH. By compiling and comparing data from previous studies involving cofactor switching mutations, we show that their effect cannot be explained as straightforward changes in volume, hydrophobicity, charge, or BLOSUM62 scores of the residues populating the cofactor binding site. Instead, we find that the use of a detailed cofactor binding energy approximation is needed to adequately capture the relative affinity towards different cofactors. The implicit solvation models Generalized Born with molecular volume integration and Generalized Born with simple switching were integrated in the iterative protein redesign and optimization (IPRO) framework to drive the redesign of Candida boidinii xylose reductase (CbXR) to function using the non‐native cofactor NADH. We identified 10 variants, out of the 8,000 possible combinations of mutations, that improve the computationally assessed binding affinity for NADH by introducing mutations in the CbXR binding pocket. Experimental testing revealed that seven out of ten possessed significant xylose reductase activity utilizing NADH, with the best experimental design (CbXR‐GGD) being 27‐fold more active on NADH. The NADPH‐dependent activity for eight out of ten predicted designs was either completely abolished or significantly diminished by at least 90%, yielding a greater than 104‐fold change in specificity to NADH (CbXR‐REG). The remaining two variants (CbXR‐RTT and CBXR‐EQR) had dual cofactor specificity for both nicotinamide cofactors.
Structure‐based design of novel Chlamydomonas reinhardtii D1‐D2 photosynthetic proteins for herbicide monitoring
Authors: Rea Giuseppina , Polticelli Fabio , Antonacci Amina , Scognamiglio Viviana , Katiyar Prashant , Kulkarni Sudhir A. , Johanningmeier Udo , Giardi Maria Teresa
Published: August 2009

The D1‐D2 heterodimer in the reaction center core of phototrophs binds the redox plastoquinone cofactors, QA and QB, the terminal acceptors of the photosynthetic electron transfer chain in the photosystem II (PSII). This complex is the target of the herbicide atrazine, an environmental pollutant competitive inhibitor of QB binding, and consequently it represents an excellent biomediator to develop biosensors for pollutant monitoring in ecosystems. In this context, we have undertaken a study of the Chlamydomonas reinhardtii D1‐D2 proteins aimed at designing site directed mutants with increased affinity for atrazine. The three‐dimensional structure of the D1 and D2 proteins from C. reinhardtii has been homology modeled using the crystal structure of the highly homologous Thermosynechococcus elongatus proteins as templates. Mutants of D1 and D2 were then generated in silico and the atrazine binding affinity of the mutant proteins has been calculated to predict mutations able to increase PSII affinity for atrazine. The computational approach has been validated through comparison with available experimental data and production and characterization of one of the predicted mutants. The latter analyses indicated an increase of one order of magnitude of the mutant sensitivity and affinity for atrazine as compared to the control strain. Finally, D1‐D2 heterodimer mutants were designed and selected which, according to our model, increase atrazine binding affinity by up to 20 kcal/mol, representing useful starting points for the development of high affinity biosensors for atrazine.
How strong are side chain interactions in the folding intermediate?
Authors: Samatova Ekaterina N. , Katina Natalia S. , Balobanov Vitaly A. , Melnik Bogdan S. , Dolgikh Dmitry A. , Bychkova Valentina E. , Finkelstein Alexei V.
Published: August 2009

Influence of 12 nonpolar amino acids residues from the hydrophobic core of apomyoglobin on stability of its native state and folding intermediate was studied. Six of the selected residues are from the A, G and H helices; these are conserved in structure of the globin family, although nonfunctional, that is, not involved in heme binding. The rest are nonconserved hydrophobic residues that belong to the B, C, D, and E helices. Each residue was substituted by alanine, and equilibrium pH‐induced transitions in apomyoglobin and its mutants were studied by circular dichroism and fluorescent spectroscopy. The obtained results allowed estimating changes in their free energy during formation of the intermediate state. It was first shown that the strength of side chain interactions in the apomyoglobin intermediate state amounts to 15–50% of that in its native state for conserved residues, and practically to 0% for nonconserved residues. These results allow a better understanding of interactions occurring in the intermediate state and shed light on involvement of certain residues in protein folding at different stages.
Differential stability of the bovine prion protein upon urea unfolding
Authors: Julien Olivier , Chatterjee Subhrangsu , Thiessen Angela , Graether Steffen P. , Sykes Brian D.
Published: August 2009

Prion diseases, or transmissible spongiform encephalopathies, are a group of infectious neurological diseases associated with the structural conversion of an endogenous protein (PrP) in the central nervous system. There are two major forms of this protein: the native and noninfectious cellular form, PrPC; and the misfolded, infectious, and proteinase K‐resistant form, PrPSc. The C‐terminal domain of PrPC is mainly α‐helical in structure, whereas PrPSc in known to aggregate into an assembly of β‐sheets, forming amyloid fibrils. To identify the regions of PrPC potentially involved in the initial steps of the conversion to the infectious conformation, we have used high‐resolution NMR spectroscopy to characterize the stability and structure of bovine recombinant PrPC (residues 121 to 230) during unfolding with the denaturant urea. Analysis of the 800 MHz 1H NMR spectra reveals region‐specific information about the structural changes occurring upon unfolding. Our data suggest that the dissociation of the native β‐sheet of PrPC is a primary step in the urea‐induced unfolding process, while strong hydrophobic interactions between helices α1 and α3, and between α2 and α3, stabilize these regions even at very high concentrations of urea.
Characterization of the SRP68/72 interface of human signal recognition particle by systematic site‐directed mutagenesis
Authors: Iakhiaeva Elena , Hinck Cynthia S. , Hinck Andrew P. , Zwieb Christian
Published: August 2009

The signal recognition particle (SRP) is a ribonucleoprotein complex which is crucial for the delivery of proteins to cellular membranes. Among the six proteins of the eukaryotic SRP, the two largest, SRP68 and SRP72, form a stable SRP68/72 heterodimer of unknown structure which is required for SRP function. Fragments 68e′ (residues 530 to 620) and 72b′ (residues 1 to 166) participate in the SRP68/72 interface. Both polypeptides were expressed in Escherichia coli and assembled into a complex which was stable at high ionic strength. Disruption of 68e′/72b′ and SRP68/72 was achieved by denaturation using moderate concentrations of urea. The four predicted tetratricopeptide repeats (TPR1 to TPR4) of 72b′ were required for stable binding of 68e′. Site‐directed mutagenesis suggested that they provide the structural framework for the binding of SRP68. Deleting the region between TPR3 and TPR4 (h120) also prevented the formation of a heterodimer, but this predicted alpha‐helical region appeared to engage several of its amino acid residues directly at the interface with 68e′. A 39‐residue polypeptide (68h, residues 570–605), rich in prolines and containing an invariant aspartic residue at position 585, was found to be active. Mutagenesis scanning of the central region of 68h demonstrated that D585 was solely responsible for the formation of the heterodimer. Coexpression experiments suggested that 72b′ protects 68h from proteolytic digestion consistent with the assertion that 68h is accommodated inside a groove formed by the superhelically arranged four TPRs of the N‐terminal region of SRP72.
Towards low energy physics from the heterotic string
Authors: Ramos‐Sánchez S.
Published: August 2009

We investigate orbifold compactifications of the heterotic string, addressing in detail their construction, classification and phenomenological potential. We present a strategy to search for models resembling the minimal supersymmetric extension of the standard model (MSSM) in ℤ6‐II orbifold compactifications. We find several MSSM candidates with the gauge group and the exact spectrum of the MSSM, and supersymmetric vacua below the compactification scale. They also exhibit the following realistic features: R‐parity, seesaw suppressed neutrino masses, and intermediate scale of supersymmetry breakdown. In addition, we find that similar models also exist in other ℤN orbifolds and in the SO(32) heterotic theory.
Parametric self pulsing in a quantum opto‐mechanical system
Authors: Holmes C.A. , Milburn G.J.
Published: August 2009

We describe an opto‐mechanical system in which the coupling between optical and mechanical degrees of freedom takes the form of a fully quantised third‐order parametric interaction. Two physical realisations are proposed: a harmonically trapped atom in a standing wave and the ‘membrane in the middle’ model. The dominant resonant interaction corresponds to a stimulated Raman process in which two phonons are converted into a single cavity photon. We show that this system can exhibit a stable limit‐cycle in which energy is periodically exchanged between optical and mechanical degrees of freedom. This is equivalently described as a parametric self‐pulsing.
Initial charge carrier dynamics in porous silicon revealed by time‐resolved fluorescence and transient reflectivity
Authors: Juška Gediminas , Medvids Arturs , Gulbinas Vidmantas
Published: August 2009

Nonequilibrium charge carrier relaxation dynamics in porous silicon was investigated by means of time‐resolved photoluminescence and ultrafast transient reflectance. Fluorescence band shift to the low energy side and intensity decay were observed during several initial nanoseconds under porous silicon excitation at 3.3 eV, and attributed to the spectral diffusion and trapped carrier recombination. Ultrafast transient reflectance pump–probe technique reveals reflectance dynamics on a several ps time scale present with 3.1 eV excitation, but absent with excitation at 1.77 eV.
Disorder effects on electronic and optical properties of the ternary GaxIn1−xP (x = 0.25, 0.50, and 0.75) alloy
Authors: Kumar S. , Parashari Satyam S. , Auluck S.
Published: August 2009

We have performed first‐principles calculations for the electronic and optical properties of GaxIn1−xP alloys for compositions x = 25, 50, and 75%. The effects of Ga composition on the electronic density of states, dielectric functions, and pressure coefficients are discussed in detail using a simple cubic structure and a special quasi‐random structure. Effective masses are calculated along the Γ(000) symmetry point. Overall, the calculated properties are in agreement with the available experimental data. Our calculations show that the direct band gap and the electron effective masses vary nonlinearly with concentration x.
Oxide glasses with magnetic nanoparticles: transparent magnets (Faraday rotation and electron magnetic resonance studies)
Authors: Edelman Irina , Kliava Janis
Published: August 2009

In the first part of this paper we outline the state of the art in the field of magnetic nanoparticles in oxide glasses. We describe the theoretical background of two complementary techniques used for the studies of the state of paramagnetic ions, clusters and magnetic particles in a diamagnetic matrix, viz., magnetooptical Faraday rotation (FR) and electron magnetic resonance (EMR) and we overview previous results obtained with these techniques for several glass systems. In the second part, we highlight the case of potassium‐alumina‐borate glasses – a glassy system where doping with paramagnetic oxides results in formation of magnetic particles at very low contents of paramagnetic additions: Fe2O3 and MnO. In the special case when the ratio of the iron and manganese oxides in the charge is 3/2, magnetic nanoparticles with characteristics close to those of manganese ferrite are formed already at the first stage of the glass preparation. After thermal treatment all glasses show FR and EMR spectra attesting to the presence of superparamagnetic nanoparticles, characterized by relatively broad size and shape distributions. The formation of magnetic nanoparticles confers to these glasses magnetic and magneto‐optical properties typical of magnetically ordered substances. At the same time, the glasses remain transparent in a part of the visible and near infrared spectral range and display a high FR value. Such properties make them particularly interesting for use as new media for various magneto‐optical devices.
Analysis of Raman modes in Mn‐doped ZnO nanocrystals
Authors: Guo Shuxia , Du Zuliang , Dai Shuxi
Published: August 2009

Mn‐doped ZnO was synthesized using a co‐precipitation technique. X‐ray diffraction (XRD) measurements and photoluminescence (PL) spectra show that Mn ions are doped into the lattice positions of ZnO. The modes at 202, 330, and 437 cm−1 in the Raman spectrum are assigned as 2E2 (low), E2 (high)–E2 (low), and E2 (high) modes of ZnO base, respectively. The mode at 528 cm−1 is ascribed to a local vibrational mode related to Mn. The mode at 580 cm−1 should be an intrinsic mode of ZnO and assigned to E1 longitudinal optical (LO). Its reinforcement should result from a combination of resonance at the excitation wavelength and impurity‐induced scattering.
Potentially predictable patterns of extratropical tropospheric circulation in an ensemble of climate simulations with the COLA AGCM
Authors: Zheng X. , Straus D. M. , Frederiksen C. S. , Grainger S.
Published: August 2009

A variance decomposition approach to estimate the potentially predictable component of seasonal means has been further developed to separately diagnose the boundary‐forced component and the slowly varying internal dynamics component. This decomposition of the potentially predictable component has been applied to an ensemble of ten 50‐year simulations of the 500 hPa geopotential height field from the Center for Ocean‐Land‐Atmosphere Studies global atmospheric model forced by sea‐surface temperatures. The model performance is analysed for the winter season and compared with the National Centers for Environmental Prediction reanalysis. The majority of the hemispheric potentially predictable patterns, identified as the empirical orthogonal functions of the potentially predictable component of the seasonal mean fields, are captured by the model. These include all the patterns forced by the El Niño–Southern Oscillation in the Southern Hemisphere, and the dominant potentially predictable patterns in the Northern Hemisphere, i.e. the Pacific–North American pattern. However, the boreal winter Western Pacific Oscillation and Tropical Northern Hemisphere pattern, which are well simulated by some other general circulation models, are not well captured. Copyright © 2009 Royal Meteorological Society
R Graphics
Authors: Murrell Paul
Published: August 2009

This article describes the graphics facilities of the R language and environment for statistical computing and graphics. There is a brief introduction to basic plotting functions in R, followed by a description of the organisation of R graphics into coherent and consistent sets of graphics functions, plus an indication of what sorts of plots each set of functions can produce. There is also a brief discussion of the limitations of R graphics.

One of the features that draws many users to R1is the graphics sub‐system. The main features that distinguish R from the many other software systems that can be used to produce plots are that R provides facilities for creating a very wide range of statistical plots, R allows for very fine control over the appearance of plots, and R produces plots that are suitable for professional publication.

This article provides an overview of the basic features of R graphics, along with some simple examples of how to produce plots using R. The general structure and organisation of R graphics is also described to give the reader some indication of how to explore R graphics system further. While some graphical user interfaces exist for R, and some of these provide menu items for producing plots, the only way to make use of the full power of the R graphics system is to write R code, so this article will only address the R code that can be used to produce plots. Copyright © 2009 John Wiley & Sons, Inc.

This article is categorized under:

Software for Computational Statistics > Software/Statistical Software
Fractional factorial design
Authors: Gunst Richard F. , Mason Robert L.
Published: August 2009

Fractional factorial designs are among the most important statistical contributions to the efficient exploration of the effects of several controllable factors on a response of interest. Fractional factorials are widely used in experiments in fields as diverse as agriculture, industry, and medical research. A key feature of fractional factorials that is not shared by more ad hoc methods for reducing the size of experiments is that the statistical properties are known in advance of experimentation. Consequently, an experimenter can investigate alternatives that enable the goals of the experiment to be met with the least cost, shortest time, or most effective use of resources. On occasion, an experimenter might decide not to conduct an experiment as originally planned once the statistical properties of the design are known. This article highlights the fundamental concepts, design strategies, and statistical properties of fractional factorial designs. Copyright © 2009 John Wiley & Sons, Inc.

This article is categorized under:

Statistical Models > Linear Models

Statistical Models > Classification Models
Centroids
Authors: Abdi Hervé
Published: August 2009

The concept of centroid is the multivariate equivalent of the mean. Just like the mean, the centroid of a cloud of points minimizes the sum of the squared distances from the points of the cloud to a point in the space. Copyright © 2009 John Wiley & Sons, Inc.

This article is categorized under:

Statistical and Graphical Methods of Data Analysis > Multivariate Analysis

Statistical Models > Multivariate Models
Implementation by implication
Authors: Fletcher Shayne
Published: August 2009

In this article, we demonstrate the application of various modern C + + implementation techniques in the development of a computer program to solve the classic problem of computing Black & Scholes implied option volatilities. Copyright © 2009 Wilmott Magazine Ltd
Potential future exposure calculations using the BGM model
Authors: Ng Leslie , Peterson Dave
Published: August 2009

We investigate the use of the Brace–Gatarek–Musiela (BGM) model in potential future exposure (PFE) calculations for various exotic interest rate products. Monte Carlo simulation is required to generate PFE scenarios. If the pricing model is also implemented using Monte Carlo simulation, PFE calculations are exceptionally demanding, involving nested Monte Carlo simulations. To reduce computation time, we look at two approximate pricing methods—a Longstaff‐Schwartz regression‐based approach, and a finite difference approach using a drift approximated BGM model. Numerical results are presented for several different exotic trade types. PFE results delivered by the two approximate methods are compared with results obtained by full resimulation, i.e. nested Monte Carlo. In the test cases we looked at, both approaches produced good results and were several orders of magnitude faster than full resimulation. However, care must be taken when using the regression‐based approach. In particular, results can vary significantly depending on the order of the polynomial basis functions used in the regressions. Copyright © 2009 Wilmott Magazine Ltd
Prospective Study of Intra‐Abdominal Pressure Following Major Elective Abdominal Surgery
Authors: Scollay John M. , de Beaux Ishrat , Parks Rowan W.
Published: August 2009

Background

Studies in emergency surgical patients have shown that raised intra‐abdominal pressure may adversely affect organ function. The major aim of the present study was to establish the incidence of intra‐abdominal hypertension (IAH) in patients undergoing major elective abdominal surgery. A secondary aim was to determine if the development of IAH was associated with poorer outcome.

Methods

Patients undergoing major elective general surgical procedures were recruited to a prospective study in which intra‐abdominal pressure was measured for 72 h postoperatively. Outcome data were collected on all patients.

Results

A total of 42 patients with a median age of 63.5 years were studied. Five patients (12%) developed IAH, but this did not lead to a significant increase in the incidence of major organ dysfunction. There was no significant difference in the median length of hospital stay. However the development of IAH was associated with delayed return to oral diet (p < 0.05).

Conclusions

Intra‐abdominal hyhpertension occurs in 12% of patients following major elective abdominal surgery and leads to a significantly delayed return to oral diet, but not to an increased length of hospital stay or increased incidence of major organ dysfunction.
In Search of Benchmarking for Mortality Following Multiple Trauma: A Swiss Trauma Center Experience
Authors: Füglistaler‐Montali Ida , Attenberger Corinna , Füglistaler Philipp , Jacob Augustinus L. , Amsler Felix , Gross Thomas
Published: August 2009

Background

The manifestations associated with non‐survival after multiple trauma may vary importantly between countries and institutions. The aim of the present study was to assess the quality of performance by comparing actual mortality rates to the literature.

Methods

The study involved evaluation of a prospective consecutive multiple trauma cohort (injury severity score, ISS > 16) primarily admitted to a university hospital. Univariate and multivariate testing of routine parameters and scores, such as the Trauma and Injury Severity Score (TRISS), was used to determine their predictive powers for mortality.

Results

The 30‐day mortality of 22.8% (n = 54) exactly matched predicted TRISS versions of Champion or the Major Trauma Outcome Study for our 237 multiple trauma patients (42.8 ± 20.9 years; ISS 29.5 ± 11.5). Univariate analysis revealed significant differences between survivors and non‐survivors when compared for age, ISS, Glasgow coma scale (GCS), pulse oximeter saturation (SapO2), hemoglobin, prothrombin time, and lactate. In multivariate analysis, age, ISS, and GCS (P < 0.001 each) functioned as major independent prognostic parameters of both 24 h and 30‐day mortality. Various TRISS versions hardly differed in their precision (area under the curve [AUC] 0.83–0.84), but they did differ considerably in their level of requirement, with the TRISS using newer National Trauma Data Bank coefficients (NTDB‐TRISS) offering the highest target benchmark (predicted mortality 13%, Z value –5.7) in the prediction of 30‐day mortality.

Conclusions

Because of the current lack of a single, internationally accepted scoring system for the prediction of mortality after multiple trauma, the comparison of outcomes between medical centers remains unreliable. To achieve effective quality control, a practical benchmarking model, such as the TRISS‐NTDB, should be used worldwide.
The Influence of Reaction Parameters on the Epoxidation of Rapeseed Oil with Peracetic Acid
Authors: Milchert Eugeniusz , Smagowicz Anna
Published: August 2009

The influence of reaction parameters on the epoxidation of rapeseed oil (RO) with peracetic acid obtained in situ from the reaction between 30 wt% hydrogen peroxide and glacial acetic acid (AA) has been studied. The course of the reaction was measured by changes of the iodine number (IN) and epoxy number (EN), used to estimate the degree of rapeseed oil conversion, yield, and the selectivity of transformation to epoxidized rapeseed oil in relation to the total amount of oil undergoing the transformation. The optimal conditions of epoxidation are as follows: temperature 60 °C, molar ratio of hydrogen peroxide to rapeseed oil 9.5:1 mol/mol, molar ratio of acetic acid to rapeseed oil 1.12:1 mol/mol, stirring speed 500 rpm, and reaction time of 4 h. Under these conditions the epoxy number is equal to 0.157 mol/100 g RO and iodine number reaches low values of 0.123 mol/100 g RO. The selectivity of transformation to epoxidized RO calculated from EN and IN is 82.2%, conversion of hydrogen peroxide is 100%, conversion of RO calculated from IN is 60.8%, and yield of RO calculated from EN is 50%.
The validity of average 8‐h pain intensity assessment in cancer patients
Authors: Caraceni Augusto , Zecca Ernesto , Martini Cinzia , Brunelli Cinzia , Pigni Alessandra , Gorni Giovanna , Galbiati Anna , Ibazeta Myrta , Hjermstad Marianne , Kaasa Stein
Published: August 2009

Aim of this study was to validate the use of subjective average pain assessment over an 8‐h time period to evaluate cancer pain intensity.

A sample of 95 consecutive cancer inpatients were asked to score on 0–10 numerical scales the intensity of their pain at hourly intervals, and then, at the 8th hour, to rate their average pain intensity over the last 8h. Agreement between the average of the 8 hourly measures (8hA) and the single patient‐rated average (PA8h) was examined with the intraclass correlation coefficient (ICC) and the absolute difference (AD) between the two measurements. Associations between AD, gender, age older than 70, somatic pain, visceral pain, neuropathic pain, pain on movement and the presence of pain exacerbations during the 8‐h period, were also examined.

Average pain intensity scores were very similar with the two measurement schedules: 3.4 for 8hA and 3.7 for PA8h, with a median AD of 0.44 points. Only six patients (6.3%) showed ADs higher than 2 points. Also the ICC (0.85) showed a substantial agreement between the two schedules. Among the examined variables, gender, age over 70years and presence of pain exacerbations showed a significant association with the agreement level.

Overall, our results support the validity of a subjective average pain measurement over 8‐h period in cancer patients.
MCL‐1ES, a novel variant of MCL‐1, associates with MCL‐1L and induces mitochondrial cell death
Authors: Kim Jae-Hong , Sim Se-Hoon , Ha Hye-Jeong , Ko Jeong-Jae , Lee Kangseok , Bae Jeehyeon
Published: August 2009

MINT‐7255756:MCL1‐ES (uniprotkb:Q07820‐2) physically interacts (MI:0914) with COX IV (uniprotkb:P13073) by anti tag coimmunoprecipitation (MI:0007)
A truncated human Ah receptor suppresses growth of human cervical tumor xenografts by interfering with hypoxia signaling
Authors: Wang Depeng , Faridi Jesika S. , Li Yanjie , Chan William K.
Published: August 2009

We used a xenograft model to investigate whether the aryl hydrocarbon receptor deletion construct CΔ553 suppresses tumor growth. HeLa cells that were infected with CΔ553 expressing adenovirus (Ad553) formed very small tumors whereas the control adenovirus‐infected cells formed large tumors at day 15. CΔ553 inhibited the formation of the HIF‐1 DNA complex and suppressed the induction of the HIF‐1α target proteins CAIX and GLUT1. The Ad553 tumors had less HIF‐1 function since they showed reduced microvessel formation and lesser amounts of HIF‐1α, Arnt, phospho‐Akt, CAIX, and GLUT1. Proteasome‐mediated Arnt degradation was enhanced in Ad553‐infected HeLa cells and tumors.
Apoptosis signal‐regulating kinase 1 regulates the expression of caspase‐11
Authors: Choi Jong-Ryoul , Heo Hyejung , Lang Yoo , Shin Ki Soon , Kang Shin Jung
Published: August 2009

Caspase‐11 is an inducible caspase involved in the regulation of cell death and inflammation. In the present study, we examined whether apoptosis signal‐regulating kinase 1 (Ask1)‐mediated signaling pathway is involved in the expression of caspase‐11 induced by lipopolysaccharide (LPS). We found that the induction of caspase‐11 was suppressed by the inhibitors of NADPH oxidase (Nox) or knockdown of Nox4 that acts downstream of toll‐like receptor 4 and generates Ask1‐activating reactive oxygen species. Overexpression of dominant negative tumor necrosis factor receptor associate factor 6 also suppressed the induction of caspase‐11. Importantly, knockdown or dominant negative form of Ask1 suppressed the induction of caspase‐11 following LPS stimulation. Taken together, our results show that Ask1 regulates the expression of caspase‐11 following LPS stimulation.
Unconventional secretion of tubby and tubby‐like protein 1
Authors: Caberoy Nora B. , Li Wei
Published: August 2009

Tubby‐like proteins (Tulps) with no signal peptide have been characterized as cytoplasmic proteins with various intracellular functions, including binding to phosphatidylinositol‐4,5‐bisphosphate [PI(4,5)P2]. PI(4,5)P2 has been implicated in unconventional secretion of fibroblast growth factor‐2 without a signal peptide. Here, we show that all Tulps are expressed intracellularly and extracellularly. Tubby secretion is partially dependent on its PI(4,5)P2‐binding activity with an essential secretory signal in the N‐terminus. Pathogenic mutation in Tubby mice has no impact on tubby extracellular trafficking. Moreover, unconventional secretion of tubby and Tulp1 is independent of endoplasmic reticulum–Golgi pathway. These data implicate that Tulps may function extracellularly as well.
Pleiotropic roles of calumenin (calu‐1), a calcium‐binding ER luminal protein, inCaenorhabditis elegans
Authors: Cho Jeong Hoon , Song Hyun-Ok , Singaravelu Gunasekaran , Sung Hyun , Oh Won-Chan , Kwon Soonjae , Kim Do Han , Ahnn Joohong
Published: August 2009

Calumenin is a Ca2+binding protein localizing at the lumen of the endoplasmic reticulum (ER). Although it has been implicated in various diseases, the in vivo functions of calumenin are largely unknown. Here, we report that calumenin has pleiotropic roles in muscle and cuticle function inCaenorhabditis elegans. Mutant analysis revealed that thecalu‐1is required for regulating fertility, locomotion and body size. In addition,calu‐1is important for two behaviors, defecation and pharyngeal pumping, consistent with its ability to bind Ca2+. The genetic analysis further suggested the possibility thatcalu‐1regulates the pharyngeal pumping together with the inositol 1,4,5‐triphosphate (IP3) receptor encoded byitr‐1. Taken together, our data suggest that calumenin is important for calcium signaling pathways inC. elegans.
High fat diet‐induced maternal obesity alters fetal hippocampal development
Authors: Niculescu Mihai D. , Lupu Daniel S.
Published: August 2009

The importance of maternal nutrition for fetal brain development is increasingly recognized. Previous studies have suggested that maternal obesity or maternal exposure to obesogenic diets may permanently alter brain structure and function in the offspring. To test whether maternal exposure to a high‐fat diet, prior and during gestation, alters fetal hippocampal development, we fed 8‐week old C57BL/6 females with a high‐fat diet (60% calories from fat) for 10 weeks prior to matting and 17 days after. Fetal brains at embryonic day E17 were used to determine developmental changes in the hippocampus. We report that maternal exposure to the high‐fat diet induced small for gestational age (SGA) status and fetal resorption. The proliferation of neural progenitors was increased in the neuroepithelium from hippocampus and cortex in fetuses from mothers fed the high‐fat diet when compared to controls, but decreased within the dentate gyrus (DG). Apoptosis in the hippocampus was decreased (Ammon's Horn and fimbria). The differentiation of calretinin‐positive neurons within the DG was also decreased.

These data indicate that, under the influence of a maternal high‐fat diet administered prior and during gestation, fetal hippocampal development is altered at embryonic day 17, as indicated by region‐specific changes in proliferation of neural precursors, decreased apoptosis, and by decreased neuronal differentiation within the dentate gyrus.
Cardiogenic arterial thromboembolism causing non-ambulatory tetraparesis in a cat
Authors: Bowles Danielle B , Coleman Michael G , Harvey Catherine J.
Published: August 2009

A 1-year-old oriental cat was presented with a peracute onset of tetraparesis and vocalisation. Clinical findings were suggestive of multi-site thromboembolic disease, and this was confirmed on post-mortem examination. An echocardiogram showed severe restrictive cardiomyopathy and spontaneous echogenic contrast. To the author's knowledge, this is the first reported case of tetraparesis secondary to cardiogenic arterial thromboembolic disease. Thromboembolic disease should be included as a differential diagnosis for any cat presented with a peracute onset of paresis or paralysis, even if there is no history of cardiac disease.
The Roman Inquisition's precept to Galileo (1616)
Authors: MAYER THOMAS F.
Published: August 2009

On 26 February 1616 Galileo was ordered to cease to defend heliocentrism in any way whatsoever. This order, called a precept, automatically applied to anything he might later attempt to publish on the subject. Issued at the end of his first trial by the Roman Inquisition, the precept became the spark that triggered his second trial in 1632–3 and figured importantly in the justification of his sentence. This precept has been a subject of controversy since the late nineteenth century for its authenticity, legality and legitimacy. This paper addresses the first two points and establishes the facts of what probably happened in 1616. It does so by examining seven texts that bear on the event. All but one of these (plus Galileo's first deposition in 1633) agree tolerably well that Galileo did indeed receive the precept in the strongest form. An examination of the singleton text in the context of how the Inquisition produced and kept its records as well as of its procedures and personnel shows that it is the least reliable source. This context also supports the argument that certainty about what happened is impossible to achieve. The theory that the document most damaging to Galileo was a forgery is also disposed of. Examination of the crucial phrase successive ac incontinenti in one of the documents supports the paper's suggestion that more caution is in order before accepting the currently nearly universal claim that the precept was improper in law.
TheBurschenschaftand German Political Culture, 1890–1914
Authors: Zwicker Lisa Fetheringill
Published: August 2009

In the history of theBurschenschaftpublished in 1939, Georg Heer wrote that with the coming of the National Socialists to power “the goals of the German Burschenschaft had been achieved; the National Socialist German Student Union had now taken over its tasks.” Of course Heer was not free to write what he wished about the 1935 dissolution of the Burschenschaft, but his interpretation is consistent with the ideas of many historians about this important organization within the history of German nationalism. Something had gone terribly wrong with this organization, despite its clear liberal and middle-class origins.
Suffragist Women, Corrupt Officials, and Waste Control in Prewar Japan: Two Plays by Kaneko Shigeri
Authors: Tamanoi Mariko Asano
Published: August 2009

Through the reading of two plays written by Kaneko Shigeri, this article examines the way in which Japanese suffragist women, who actively participated in the local governance of Tokyo in prewar Japan, joined in the production of two mutually related sets of discourses on democracy and waste control. Relying on the idea of “purity” (jôka), these women gendered the discourse of democracy along the divide of “pure” women and “impure” men, and succeeded, to a certain extent, in eliminating corrupt officials from the Tokyo prefectural and city assemblies. Yet their efforts to control waste, which was dumped on the residents of Fukagawa Ward in lowland Tokyo, largely failed, for suffragist women hardly paid attention to the intricate relationships among gender, class, and space in Greater Tokyo. This article aims to reveal the limit of the ideas of democracy and environment shared among the suffragist women in prewar Japan.
The Word Is Mightier than the Throne: Bucking Colonial Education Trends in Manchukuo
Authors: Hall Andrew
Published: August 2009

Japanese within the Manchukuo education bureaucracy stood out from their contemporaries in other Japanese colonies in their opposition to including militaristic and Japanese emperor-centered materials in the schools. As late as 1943, they published textbooks that focused on the students' daily lives rather than on encouraging respect for the military or reverence for the Japanese imperial family. Here, the author discusses how the congruence of an attempt by Manchukuo authorities at gaining authenticity and the progressive background of leading Japanese educators in the region brought about an education system that was unlike any other in the Japanese empire. Using Manchukuo textbooks, education journals, and postwar memoirs, the author examines a school of thought among Japanese colonial language educators, referred to as “reform optimists,” who held that whole language education could solve the contradiction between Manchukuo's stated ideal of ethnic equality and the reality of Japanese domination.