bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of Ringing Response of a Gravity Based Structure in Extreme Sea States
Authors: Kim Jang , Tan Jaime Hui Choo , Magee Allan , Wu Guangyu , Paulson Steve , Davies Bill
Published: November 2013

In designing fixed offshore platforms located in regions of severe wave conditions, the potential resonant response of the hull structure due to wave loads must be checked. Since the natural frequency of vibration of the hull structure is typically much higher than the dominant design wave frequency, conventional wave load analysis based on linear wave theory does not show dynamic amplification. However, it is known that steep waves are nonlinear and may contain significant energy at higher harmonics of the fundamental frequency. When the forcing frequency of the higher-harmonic wave load is close to the natural frequency of the structural vibration, a resonance i.e. ringing will occur and the structural dynamic response will be significantly amplified.

This paper describes an analysis procedure to estimate high-frequency dynamic load on a Gravity Based Structure (GBS) exposed to severe sea states using Computational Fluid Dynamics (CFD) analysis and modal analysis. To fill the statistical gap between the extreme values from short-duration CFD-modal analysis and that from 3-hour design sea states, an approximation method has been developed to estimate the global dynamic load from the measured quasi-static load in earlier model test and to obtain a calibration factor for the CFD-modal analysis results.
The Use of INS and GPS and the Post-Processing Method in Field Measurement of Mega Jacket Launch
Authors: Chen Yining , Li Xin , Chen Gang , Li Jun , Zhang Ding
Published: November 2013

This paper presents the post-processing method used for field measurement of mega jacket launch. The Liwan 3-1 mega jacket was successfully launched at a water depth of 190 meters in South China Sea on August 30, 2012. In order to study the influence between the jacket and the launch barge, the field measurement is designed to record the trajectory of both the jacket and the launch barge. Both Inertial Navigation System (INS) and Global Positioning System (GPS) are used to ensure the accuracy of the field measurement. The GPS has a higher accuracy but cannot work underwater. Therefore the INS is used to measure the trajectory motion of the launched jacket when the jacket completely goes into water. Since only INS can record the accelerations in 3 degrees in inertia coordinate system when the jacket is completely under water, a special method will be used to transfer the initial acceleration data to those in the geographic coordinate system, combined with the position data recorded by GPS when it works, we can get a relatively accurate launch trajectory of the jacket. In this paper, we focus on the method used for transferring the initial data recorded by INS and GPS to the trajectories of both jacket and barge.
Fatigue Assessment of Threaded Segment Specimens Based on the Weakest Link Theory
Authors: Fjeldstad Arne , Wormsen Anders , Kirkemo Finn
Published: November 2013

In this paper, the weakest link approach has been used to estimate the fatigue life of threaded segment specimens based on fatigue test data of smooth specimens of the same material. The segment specimens are cut outs from an ACME threaded component with a thread geometry typically used in subsea connectors.

Fatigue life estimates of the threaded specimens were also made by means of the local stress approach which is often the prescribed method in standards and recommended practices, such as DNV-RP-C203. This method uses the von Mises stress range at the most severe location of the specimen when estimating the fatigue life.

The estimated S–N curve based on the weakest link approach shows good correspondence with fatigue test results of the threaded segment specimens. The estimated S–N curve based on the local stress approach is well below the S–N curve for the threaded segment specimen. A factor between two and three on stress is observed. Hence, the inherent level of conservatism related to the local stress approach when assessing the fatigue strength of components with very high stress concentration factors is considered to be high.
Carbon Dioxide Sequestration in Portland Cement Paste Modified With Cellulose Microcrystalline
Authors: Hoyos Catalina Gómez , Vazquez Analia
Published: November 2013

This work evaluated the dynamical mechanical properties of Portland cement paste modified with cellulose microcrystalline (MCC) before and after exposition to CO2 saturated environment during 4 h. All the cement paste samples were subjected to thermogravimetrical analysis (TGA) before and after carbonation process. Changes in morphology of the samples were studied in a field emission electron microscope (FE-SEM); additionally changes generated in hydration kinetic by the addition of MCC to cement paste, were followed by measuring the adiabatic temperature during the first 24 h of reaction. The addition of MCC delayed the hydration reaction. TGA results shown that cement past with MCC was carbonated. The carbonation process in TGA was evaluated by the increase in the size of the peak around 680 oC related with calcium carbonate thermal degradation. The dynamical mechanical analysis shown that, cement paste with MCC increased significantly its storage modulus after CO2 exposition.
Extreme Directional and Planar Profiles for Kuroshio Current Using Inverse FORM and Proper Orthogonal Decomposition
Authors: Agarwal Puneet , McNeill Scot , Saruhashi Tomokazu , Sawada Ikuo , Kyo Masanori , Miyazaki Eigo , Yamazaki Yasuyuki , Aoike Kan
Published: November 2013

Kuroshio is a major global current that flows near the east coasts of Taiwan and Japan. Kuroshio is a relatively strong current with typical speeds of 3 to 5 knots at the water surface. It is important to properly understand extreme current profiles of these currents for any drilling activity since the response of deepwater risers is known to be sensitive to the shape of the current profile. This paper presents the derivation of extreme two-dimensional (i.e., directional) and planar profiles for Kuroshio currents at a site in Nankai Trough, Japan; water depth is almost 2000 m. About 6000 currents profiles measured over six months in 2010 by JAMSTEC are used. The inverse first-order reliability method (inverse FORM) and proper orthogonal decomposition (POD) technique are employed. While such methodology is well established, its use for this site posed several challenges. Firstly, the first two modes contribute only about 90% of the energy. Therefore, as many as seven modes were included for accuracy. Since an exact solution requiring joint probability distribution for seven variables becomes quite cumbersome, reasonable simplifications were made for efficient calculations. Second, to preserve the directionality in extreme currents, the inverse FORM problem for the two orthogonal components of the current velocity was simultaneously solved, so that extreme profiles for the two planar directions are obtained. Doing so implies solving a four-dimensional inverse FORM problem, even if the full joint distribution of first two modal weights for each direction is used. This four-dimensional problem was reduced to two related two-dimensional problems, wherein the modal vectors in the orthogonal directions are assumed independent; this assumption was found to be valid for this data set. A set containing a limited number of extreme N-year current profiles is derived using the above methodology. It is found that most of the shapes observed in the measured Kuroshio current data are represented in this set of extreme current profiles. The largest riser response obtained from all these current profiles would be the N-year response. A single extreme N-year profile is often sought in analysis, which is also derived from the set of N-year profiles by selecting the profile which maximizes an assumed response function. In summary, this paper presents extreme currents for a site on which little literature exists, and introduces a methodology to derive extreme directional current profiles from measured data.
Effects of the Presence of CO2 at the Well/Caprock Interface: Crystallization Damage
Authors: Manzanal Diego , Pereira Jean-Michel
Published: November 2013

In the context of CO2 geological storage, it is important to assess the safety and efficiency of the storage operation and thus to prevent CO2 leakage. Most probable leakage paths are constituted by the natural (faults) or artificial (around wells) interfaces.

In this study, the effects of the presence of carbon dioxide on the behaviour of a particular interface are considered. A chemo-poro-mechanical model for the excavated damaged zone located at the interface between the injection well cement and the caprock has been developed. This constitutive model accounts for the precipitation of calcium carbonates coming from the carbonation of the well cement. Crystallisation pressure induced by these carbonates modifies the stress state in the materials at the interface. The model couples a simplified chemistry of carbonates precipitation with a poro-mechanical model accounting for damage of geomaterials due to tensile stress states. This poro-mechanical model is developed at the macroscale but an insight into the material’s microstructure is also included through a description of the material’s pore size distribution and its evolution with crystallisation and damage.
Three Dimensional Fully Localized Waves on Ice-Covered Ocean
Authors: Liang Yong , Alam M.-Reza
Published: November 2013

We have recently shown [1] that fully-localized three-dimensional wave envelopes (so-called dromions) can exist and propagate on the surface of ice-covered waters. Here we show that the inertia of the ice can play an important role in the size, direction and speed of propagation of these structures. We use multiple-scale perturbation technique to derive governing equations for the weakly nonlinear envelope of monochromatic waves propagating over the ice-covered seas. We show that the governing equations simplify to a coupled set of one equation for the envelope amplitude and one equation for the underlying mean current. This set of nonlinear equations can be further simplified to fall in the category of Davey-Stewartson equations [2]. We then use a numerical scheme initialized with the analytical dromion solution of DSI (i.e. shallow-water and surface-tension dominated regimes of Davey-Stewartson equation) to look for dromion solution of our equations. Dromions can travel over long distances and can transport mass, momentum and energy from the ice-edge deep into the solid ice-cover that can result in the ice cracking/breaking and also in posing dangers to icebreaker ships.
Reconstruction of the Experimental Slamming Force Distribution Based on POD
Authors: Dessi Daniele
Published: November 2013

A new technique for determining the continuous hydrodynamic load distribution along a slender floating body on the basis of a small set of force data is presented. This technique is based on a combination of proper orthogonal decomposition and polynomial spline approximation under integral constraints. The input data are provided by the time-histories of the lumped vertical forces acting on several longitudinal portions (segments) of a segmented-hull model. The set of force data, obtained by subtracting from the total force the Froude-Krylov force, defines the vector process to which POD is applied. The tests are carried out in regular waves with a choice of model speed and wave parameters so as slamming occurs. The identified distribution of force per unit length over the impacting hull segments is then compared with a modified Von-Karman model (with 3D correction) which accounts for the water uprise in the expression of the slamming force and variable entry velocity.
Development of a New Fatigue Testing Machine for High Frequency Fatigue Damage Assessment
Authors: Osawa Naoki , Nakamura Tetsuya , Yamamoto Norio , Sawamura Junji
Published: November 2013

A new simple fatigue testing machine, which can carry out fast and low-cost fatigue tests of welded joints subject to wave with high frequency vibration, has been developed. This machine is designed for plate bending type fatigue tests, and wave load is applied by using motors with eccentric mass. Springing vibration is superimposed by attaching an additional vibrator to the test specimen, and whipping vibration is superimposed by an intermittent hammering.

Fatigue tests which simulate springing and whipping by a conventional servo-type fatigue testing machines are very expensive and use a large amount of electricity. If one uses these conventional machines, it is difficult to simulate superimposed stress wave forms at high speed, and it takes long hours of testing to examine the high frequency effect. In contrast, it is found that fatigue tests can be carried out in fast, i.e. waves with 10Hz or higher frequency for out-of-plane gusset welded joint specimens with 12mm plate thickness by using the developed machine. The electricity to be used for fatigue tests could be minimal, for example one thousandth of that needed for conventional machines. These results demonstrate the superiority of the developed machine.
A Small Scale Field Experiment for Hydrodynamic Coefficients of Morison’s Forces in Random Waves
Authors: Arena Felice , Fiamma Vincenzo
Published: November 2013

The paper deals with wave forces on vertical and horizontal cylinders through the Morison’s equation. In particular, the hydrodynamics coefficients on cylinders are investigated by means of two small scale field experiments in the Natural Ocean Engineering Laboratory (NOEL) of the Mediterranea University of Reggio Calabria, by analyzing two stationary random processes of time: the measured wave force Fa(t), and the wave force calculated with the Morison equation Fc(t). The kinematics in the Morison’s equation is obtained with the theory of wind-generated waves from the directional wave spectrum obtained from measurements of surface waves. Starting from the measurements a new approach is proposed for the evaluation of the hydrodynamic coefficients of Morison’s forces for random sea waves. Finally, the distributions of the peaks of the random wave forces, Fa(t), and Fc(t), is achieved.
Parametric Roll of High Speed Ships in Regular Waves
Authors: Moideen Hisham , Somayajula Abhilash , Falzarano Jeffrey M.
Published: November 2013

Analysis of ship parametric roll has generally been restricted to simple analytical models and sophisticated time domain simulations. Simple analytical models do not capture all the critical dynamics while time-domain simulations are often time consuming to implement. The model presented in this paper captures the essential dynamics of the system without over simplification. This work incorporates various important aspects of the system and assesses the significance of including or ignoring these aspects. Special consideration is given to the fact that a hull form asymmetric about the design waterline would not lead to a perfectly harmonic variation in metacentric height. Many of the previous works on parametric roll make the assumption of linearized and harmonic behavior of the time-varying restoring arm or metacentric height. This assumption enables modeling the roll motion as a Mathieu equation. This paper provides a critical assessment of this assumption and suggests modeling the roll motion as a Hills equation. Also the effects of non-linear damping are included to evaluate its effect on the bounded parametric roll amplitude in a simplified manner.
Second-Order Kinematics Underneath Irregular Waves
Authors: Birknes Jørn , Hagen Øistein , Johannessen Thomas B. , Lande Øystein , Nestegård Arne
Published: November 2013

The present paper is concerned with the prediction of horizontal velocities underneath measured irregular wave surface elevations. The simple case of unidirectional waves in deep water is considered. The main challenge in calculating accurately the kinematics in the crest region is related to the treatment of the contribution from wave components with frequencies much higher than the frequencies near the spectral peak. When using linear or weakly nonlinear perturbation methods, the wave components are superimposed at the still water level and it is necessary to truncate the tail of the spectrum in order to calculate accurately the velocity in the crest region.

In the present paper, results from three methods of calculating the crest kinematics are compared with the model test results of Skjelbreia et al. [1]:

• The second-order model of Stansberg et al. [5] which truncates consistently the high frequency part of the spectrum.

• The second-order model of Johannessen [13] which calculates the velocity directly at the instantaneous free surface.

• The Wheeler [3] stretching method which stretches the linear velocity profile from the still water level to the instantaneous free surface.

In addition to comparing the horizontal velocity profiles underneath the crest, time traces of horizontal velocity is compared at the free surface in the vicinity of a large crest. The latter comparison highlights the differences between the models and the challenge of accurate predictions close to top of crest. All three models show a reasonable agreement with model test results although it is clear that the first two methods are superior to the Wheeler method.
Three-Dimensional Periodic Fully Nonlinear Potential Waves
Authors: Chalikov Dmitry , Babanin Alexander V.
Published: November 2013

An exact numerical scheme for a long-term simulation of three-dimensional potential fully-nonlinear periodic gravity waves is suggested. The scheme is based on a surface-following non-orthogonal curvilinear coordinate system and does not use the technique based on expansion of the velocity potential. The Poisson equation for the velocity potential is solved iteratively. The Fourier transform method, the second-order accuracy approximation of the vertical derivatives on a stretched vertical grid and the fourth-order Runge-Kutta time stepping are used. The scheme is validated by simulation of steep Stokes waves. The model requires considerable computer resources, but the one-processor version of the model for PC allows us to simulate an evolution of a wave field with thousands degrees of freedom for hundreds of wave periods. The scheme is designed for investigation of the nonlinear two-dimensional surface waves, for generation of extreme waves as well as for the direct calculations of a nonlinear interaction rate. After implementation of the wave breaking parameterization and wind input, the model can be used for the direct simulation of a two-dimensional wave field evolution under the action of wind, nonlinear wave-wave interactions and dissipation. The model can be used for verification of different types of simplified models.
A Frequency-Domain, Finite-Order Representation of a Catenary Riser’s Dominant Nonlinear Dynamics
Authors: Kazangas Dimitris C. , Xiros Nikolaos I. , Chatjigeorgiou Ioannis K.
Published: November 2013

A numerical simulation and system identification approach to the dynamic equilibrium of a catenary riser has been developed. A finite DOF representation of the dominant dynamics is constructed using frequency domain identification by applying nonlinear signal theory techniques on response data series when exciting the structure with sinusoidal motions at the top. Data series are obtained through numerical integration of a finite differences simulation model on the basis of the six nonlinear partial differential equations describing the riser dynamics. Dynamic equilibrium is mathematically formulated by the very same equations that implicate both geometric and hydrodynamic nonlinearities; the latter are depicted by Morison’s formula. Thus, spatio-temporal series are generated for riser bending moments induced by sinusoidal heave motions of various amplitudes and frequencies. These data are consequently transformed to the frequency domain where complex Singular Value Decomposition is applied in order to derive the full nonlinear spectrum. The significant harmonics of the riser’s spectrum for the bending moment on the 2D plane of reference are demonstrated to be the three lower odd harmonics and a set of orthogonal modes for these three significant harmonics is derived. The methodology proposed is finally applied to a typical test case for validation.
Drilling Riser VIV Tests With Prototype Reynolds Numbers
Authors: Lie Halvor , Braaten Henning , Szwalek Jamison , Russo Massimiliano , Baarholm Rolf
Published: November 2013

For deep-water riser systems, Vortex Induced Vibrations (VIV) may cause significant fatigue damage. It appears that the knowledge gap of this phenomenon is considerable and this has caused a high level of research activity over the last decades. Small scale model tests are often used to investigate VIV behaviour. However, one substantial uncertainty in applying such results is scaling effects, i.e. differences in VIV response in full scale flow and small scale flow. To (partly) overcome this obstacle, a new innovative VIV test rig was designed and built at MARINTEK to test a rigid full scale riser model. The rigid riser model is mounted vertically and can either be elastically mounted or be given a forced motion. In the present version, the cylinder can only move in the cross-flow (CF) direction and is restricted in the in-line (IL) direction.

The paper reports results from a drilling riser VIV experiment where the new rest rig has been used. The overall objective of the work is to study possible VIV suppression to improve operability of retrievable riser systems with auxiliary lines by adding riser fins. These fins are normally used as devices for protection of the auxiliary lines.

The test program has recently been completed and analysis is an on-going activity. However, some results can be reported at this stage and more results are planned to be published.

A bare riser model was used in a Reynolds number (Rn) scaling effect study. The riser model was elastically mounted and towed over a reduced velocity range around 4 – 10 in two different Rn ranges, 75 000 – 192 000 (subcritical regime) and 347 000 – 553 000 (critical regime). The difference in the displacement amplitude to diameter ratio, A/D, is found to be significant.

The elastically mounted riser was also towed with various drilling riser configurations in order to study VIV/galloping responses. One configuration included a slick joint riser model with 6 kill & choke lines; another has added riser fins too. The riser model is based on a specific drilling riser and the kill and choke lines have various diameters and have a non-symmetrical layout.

The various riser configurations have also been used in forced motion tests where the towed model has been given a sinusoidal CF motion. Forces have been measured. Determination of the force coefficients is still in progress and is planned to be reported later.

Scaling effects appear to be a significant uncertainty and further research on the subject is recommended.

The slick joint drilling riser configuration generally increased the displacements compared to displacements of the bare riser model. The drilling riser configuration with protection fins, kill and choke lines generally reduced the displacements compared to displacements of the bare riser model. For both riser systems, tests showed that the response is sensitive to the heading of the current.
Incidence Density of Invasive Fungal Infections during Primary Antifungal Prophylaxis in Newly Diagnosed Acute Myeloid Leukemia Patients in a Tertiary Cancer Center, 2009 to 2011
Authors: Gomes Marisa Z. R. , Mulanovich Victor E. , Jiang Y. , Lewis Russell E. , Kontoyiannis Dimitrios P.
Published: November 2013

Although primary antifungal prophylaxis (PAP) is routinely administered in patients with acute myeloid leukemia (AML) during remission-induction and consolidation chemotherapy, the impact of PAP on the incidence of invasive fungal infections (IFIs) is not well described. We retrospectively analyzed the incidence of IFIs in 152 patients with AML who had been admitted to a tertiary cancer center between August 2009 and March 2011 and received PAP within 120 days after first remission-induction chemotherapy. We excluded patients who had undergone stem cell transplantation. Patients received a PAP drug with anti-
Aspergillus
activity during 72% (7,660/10,572) of prophylaxis-days. The incidence of documented IFIs (definite or probable according to revised European Organization for Research and Treatment of Cancer [EORTC] criteria) was 2.0/1,000 prophylaxis-days (95% confidence interval [CI], 1.23 to 3.04). IFIs due to molds were more common than IFIs due to yeasts (1.5/1,000 prophylaxis-days versus 0.4/1,000 prophylaxis-days;
P
= 0.01). Echinocandin-based PAP (8.6 and 7.1/1,000 prophylaxis-days, respectively) was associated with higher rates of documented IFIs than anti-
Aspergillus
azoles (voriconazole or posaconazole) (2.4 and 1.1/1,000 prophylaxis-days, respectively) at both 42 days (
P
= 0.03) and 120 days (
P
< 0.0001) after first remission-induction chemotherapy. The incidence of overall (documented and presumed) IFIs (
P
< 0.001), documented IFIs (
P
< 0.01), and empirical antifungal therapies (
P
< 0.0001) was higher during the first 42 days than after day 42. Despite the broad use of PAP with anti-
Aspergillus
activity, IFIs, especially molds, remain a significant cause of morbidity and mortality in AML patients, predominantly during the remission-induction phase. Patients receiving echinocandin-based PAP experienced higher rates of IFIs than did those receiving anti-
Aspergillus
azoles.
Novel Cell-Based Hepatitis C Virus Infection Assay for Quantitative High-Throughput Screening of Anti-Hepatitis C Virus Compounds
Authors: Hu Zongyi , Lan Keng-Hsin , He Shanshan , Swaroop Manju , Hu Xin , Southall Noel , Zheng Wei , Liang T. Jake
Published: November 2013

Therapy for hepatitis C virus (HCV) infection has advanced with the recent approval of direct-acting antivirals in combination with peginterferon and ribavirin. New antivirals with novel targets are still needed to further improve the treatment of hepatitis C. Previously reported screening methods for HCV inhibitors either are limited to a virus-specific function or apply a screening method at a single dose, which usually leads to high false-positive or -negative rates. We developed a quantitative high-throughput screening (qHTS) assay platform with a cell-based HCV infection system. This highly sensitive assay can be miniaturized to a 1,536-well format for screening of large chemical libraries. All candidates are screened over a 7-concentration dose range to give EC
50
s (compound concentrations at 50% efficacy) and dose-response curves. Using this assay format, we screened a library of pharmacologically active compounds (LOPAC). Based on the profile of dose-dependent curves of HCV inhibition and cytotoxicity, 22 compounds with adequate curves and EC
50
s of <10 μM were selected for validation. In two additional independent assays, 17 of them demonstrated specific inhibition of HCV infection. Ten potential candidates with efficacies of >70% and CC
50
s (compound concentrations at 50% cytotoxicity) of <30 μM from these validated hits were characterized for their target stages in the HCV replication cycle. In this screen, we identified both known and novel hits with diverse structural and functional features targeting various stages of the HCV replication cycle. The pilot screen demonstrates that this assay system is highly robust and effective in identifying novel HCV inhibitors and that it can be readily applied to large-scale screening of small-molecule libraries.
Members of the Conserved DedA Family Are Likely Membrane Transporters and Are Required for Drug Resistance in Escherichia coli
Authors: Kumar Sujeet , Doerrler William T.
Published: November 2013

Bacterial resistance to antibiotics and biocides is an increasing public health problem. Genes encoding integral membrane proteins belonging to the DedA family are present in most bacterial genomes, including
Escherichia coli
. An
E. coli
strain lacking partially redundant DedA family genes
yqjA
and
yghB
(strain BC202) displays temperature sensitivity and cell division defects. These phenotypes can be corrected by overexpression of
mdfA
, an Na
+
-K
+
/H
+
antiporter of the major facilitator superfamily. We show that BC202 is hypersensitive to several biocides and cationic compounds that are known substrates of several multidrug resistance transporters, including MdfA, EmrE, and AcrB. The introduction of deletions of genes encoding these drug transporters into BC202 results in additional sensitivity. Expression of wild-type
yghB
or
yqjA
can restore drug resistance, but this is eliminated upon mutation of two membrane-embedded acidic amino acids (E39 or D51 in either protein). This dependence upon membrane-embedded acidic amino acids is a hallmark of proton-dependent antiporters. Overexpression of
mdfA
in BC202 or artificially restoring proton motive force (PMF) restores wild-type resistance to substrates of MdfA as well as other drug resistance transporters such as EmrE and AcrAB. These results suggest that YqjA and YghB may be membrane transporters required for PMF-dependent drug efflux in
E. coli
.
Impact of Surfactant Protein D, Interleukin-5, and Eosinophilia on Cryptococcosis
Authors: Holmer Stephanie M. , Evans Kathy S. , Asfaw Yohannes G. , Saini Divey , Schell Wiley A. , Ledford Julie G. , Frothingham Richard , Wright Jo Rae , Sempowski Gregory D. , Perfect John R.
Published: November 2013

Cryptococcus neoformansis an opportunistic fungal pathogen that initiates infection following inhalation. As a result, the pulmonary immune response provides a first line of defense againstC. neoformans. Surfactant protein D (SP-D) is an important regulator of pulmonary immune responses and is typically host protective against bacterial and viral respiratory infections. However, SP-D is not protective againstC. neoformans. This is evidenced by previous work from our laboratory demonstrating that SP-D-deficient mice infected withC. neoformanshave a lower fungal burden and live longer than wild-type (WT) control animals. We hypothesized that SP-D alters susceptibility toC. neoformansby dysregulating the innate pulmonary immune response following infection. Thus, inflammatory cells and cytokines were compared in the bronchoalveolar lavage fluid from WT and SP-D−/−mice afterC. neoformansinfection. Postinfection, mice lacking SP-D have reduced eosinophil infiltration and interleukin-5 (IL-5) in lung lavage fluid. To further explore the interplay of SP-D, eosinophils, and IL-5, mice expressing altered levels of eosinophils and/or IL-5 were infected withC. neoformansto assess the role of these innate immune mediators. IL-5-overexpressing mice have increased pulmonary eosinophilia and are more susceptible toC. neoformansinfection than WT mice. Furthermore, susceptibility of SP-D−/−mice toC. neoformansinfection could be restored to the level of WT mice by increasing IL-5 and eosinophils by crossing the IL-5-overexpressing mice with SP-D−/−mice. Together, these studies support the conclusion that SP-D increases susceptibility toC. neoformansinfection by promotingC. neoformans-driven pulmonary IL-5 and eosinophil infiltration.
Outer Membrane Protein P5 Is Required for Resistance of Nontypeable Haemophilus influenzae to Both the Classical and Alternative Complement Pathways
Authors: Rosadini Charles V. , Ram Sanjay , Akerley Brian J.
Published: November 2013

The complement system is an important first line of defense against the human pathogen
Haemophilus influenzae
. To survive and propagate
in vivo
,
H. influenzae
has evolved mechanisms for subverting this host defense, most of which have been shown to involve outer surface structures, including lipooligosaccharide glycans and outer surface proteins. Bacterial defense against complement acts at multiple steps in the pathway by mechanisms that are not fully understood. Here we identify outer membrane protein P5 as an essential factor in serum resistance of both
H. influenzae
strain Rd and nontypeable
H. influenzae
(NTHi) clinical isolate NT127. P5 was essential for resistance of Rd and NT127 to complement in pooled human serum. Further investigation determined that P5 expression decreased cell surface binding of IgM, a potent activator of the classical pathway of complement, to both Rd and NT127. Additionally, P5 expression was required for NT127 to bind factor H (fH), an important inhibitor of alternative pathway (AP) activation. Collectively, the results obtained in this work highlight the ability of
H. influenzae
to utilize a single protein to perform multiple protective functions for evading host immunity.
Key Role of Toll-Like Receptor 2 in the Inflammatory Response and Major Histocompatibility Complex Class II Downregulation in Brucella abortus-Infected Alveolar Macrophages
Authors: Ferrero Mariana C. , Hielpos M. Soledad , Carvalho Natalia B. , Barrionuevo Paula , Corsetti Patricia P. , Giambartolomei Guillermo H. , Oliveira Sergio C. , Baldi Pablo C.
Published: November 2013

Alveolar macrophages (AM) seem to constitute the main cellular target of inhaled brucellae. Here, we show thatBrucella abortusinvades and replicates in murine AM without inducing cytotoxicity.B. abortusinfection induced a statistically significant increase of tumor necrosis factor alpha (TNF-α), CXCL1 or keratinocyte chemoattractant (KC), interleukin-1β (IL-1β), IL-6, and IL-12 in AM from C57BL/6 mice and BALB/c mice, but these responses were generally weaker and/or delayed compared to those elicited in peritoneal macrophages. Studies using knockout mice for TLR2, TLR4, and TLR9 revealed that TNF-α and KC responses were mediated by TLR2 recognition.Brucellainfection reduced in a multiplicity of infection-dependent manner the expression of major histocompatibility complex class II (MHC-II) molecules induced by gamma interferon (IFN-γ) in AM. The same phenomenon was induced by incubation with heat-killedB. abortus(HKBA) or the lipidated form of the 19-kDa outer membrane protein ofBrucella(L-Omp19), and it was shown to be mediated by TLR2 recognition. In contrast, no significant downregulation of MHC-II was induced by either unlipidated Omp19 orBrucellaLPS. In a functional assay, treatment of AM with either L-Omp19 or HKBA reduced the MHC-II-restricted presentation of OVA peptides to specific T cells. One week after intratracheal infection, viableB. abortuswas detected in AM from both wild-type and TLR2 KO mice, but CFU counts were higher in the latter. These results suggest thatB. abortussurvives in AM after inhalatory infection in spite of a certain degree of immune control exerted by the TLR2-mediated inflammatory response. Both the modest nature of the latter and the modulation of MHC-II expression by the bacterium may contribute to such survival.
The Core Promoter of the Capsule Operon of Streptococcus pneumoniae Is Necessary for Colonization and Invasive Disease
Authors: Shainheit Mara G. , Mulé Matthew , Camilli Andrew
Published: November 2013

Streptococcus pneumoniae
is a commensal of the human nasopharynx but can cause invasive diseases, including otitis media, pneumonia, sepsis, and meningitis. The capsular polysaccharide (capsule) is a critical virulence factor required for both asymptomatic colonization and invasive disease, yet the expression level is different in each anatomical site. During colonization, reduced levels of capsule promote binding to the host epithelium and biofilm formation, while during systemic infection, increased capsule is required to evade opsonophagocytosis. How this regulation of capsule expression occurs is incompletely understood. To investigate the contribution of transcriptional regulation on capsule level in the serotype 4 strain TIGR4, we constructed two mutants harboring a constitutive promoter that was either comparably weaker (P

cat

) or stronger (P

tRNAGlu

) than the wild-type (WT) capsule promoter, P

cps

. Mild reductions in
cpsA
and
cpsE
transcript levels in the P

cat

promoter mutant resulted in a 2-fold reduction in total amounts of capsule and in avirulence in murine models of lung and blood infection. Additionally, the P

tRNAGlu

mutant revealed that, despite expressing enhanced levels of
cpsA
and
cpsE
and possessing levels of capsule comparable to those of WT TIGR4, it was still significantly attenuated in all tested
in vivo
niches. Further analysis using chimeric promoter mutants revealed that the WT −10 and −35 boxes are required for optimal nasopharyngeal colonization and virulence. These data support the hypothesis that dynamic transcriptional regulation of the capsule operon is required and that the core promoter region plays a central role in fine-tuning levels of capsule to promote colonization and invasive disease.
Taking up physical activity in later life and healthy ageing: the English longitudinal study of ageing
Authors: Hamer Mark , Lavoie Kim L , Bacon Simon L
Published: November 2013

Background

Physical activity is associated with improved overall health in those people who survive to older ages, otherwise conceptualised as healthy ageing. Previous studies have examined the effects of mid-life physical activity on healthy ageing, but not the effects of taking up activity later in life. We examined the association between physical activity and healthy ageing over 8 years of follow-up.

Methods

Participants were 3454 initially disease-free men and women (aged 63.7±8.9 years at baseline) from the English Longitudinal Study of Ageing, a prospective study of community dwelling older adults. Self-reported physical activity was assessed at baseline (2002–2003) and through follow-up. Healthy ageing, assessed at 8 years of follow-up (2010-2011), was defined as those participants who survived without developing major chronic disease, depressive symptoms, physical or cognitive impairment.

Results

At follow-up, 19.3% of the sample was defined as healthy ageing. In comparison with inactive participants, moderate (OR, 2.67, 95% CI 1.95 to 3.64), or vigorous activity (3.53, 2.54 to 4.89) at least once a week was associated with healthy ageing, after adjustment for age, sex, smoking, alcohol, marital status and wealth. Becoming active (multivariate adjusted, 3.37, 1.67 to 6.78) or remaining active (7.68, 4.18 to 14.09) was associated with healthy ageing in comparison with remaining inactive over follow-up.

Conclusions

Sustained physical activity in older age is associated with improved overall health. Significant health benefits were even seen among participants who became physically active relatively late in life.
Unruptured intracranial aneurysms conservatively followed with serial CT angiography: could morphology and growth predict rupture?
Authors: Mehan William A , Romero Javier M , Hirsch Joshua A , Sabbag David J , Gonzalez Ramon G , Heit Jeremy J , Schaefer Pamela W
Published: November 2013

Background and purpose

Despite several landmark studies, the natural history of unruptured intracranial aneurysms (UIA) remains uncertain. Our aim was to identify or confirm factors predictive of rupture of UIA being observed conservatively with serial CT angiography (CTA) in a North American patient population.

Methods

We performed a retrospective review of patients with UIA being followed with serial CTA studies from 1999 to 2010. The following features for each aneurysm were cataloged from the official radiologic reports and CTA images: maximum diameter, growth between follow-up studies, location, multiplicity, wall calcification, intraluminal thrombus and morphology. Univariate logistic regression analysis of the potential independent risk factors for aneurysm rupture was performed. Statistically significant risk factors from the univariate analysis were then entered into a multivariate logistic regression analysis.

Results

152 patients with a total of 180 UIA had at least two CTA studies. Six aneurysms in six different patients ruptured during the CTA follow-up period for an overall rupture rate of 3.3% and an annual rupture rate of 0.97%. All ruptured aneurysms were ≥9 mm. In the univariate analysis, the statistically significant predictors of aneurysm rupture were aneurysm size (p=0.003), aneurysm growth (p<0.0001) and aneurysm multilobulation (p=0.001). The risk factors that remained significant following the multivariate analysis were growth (OR 55.9; 95% CI 4.47 to 700.08; p=0.002) and multilobulation (OR 17.4; 95% CI 1.52 to 198.4; p=0.022).

Conclusions

Aneurysm morphology and interval growth are characteristics predictive of a higher risk of subsequent rupture during conservative CTA follow-up.
Extended multivariate approach for uncertainty reduction in the assessment of undrained shear strength in clays
Authors: Müller Rasmus , Larsson Stefan , Spross Johan
Published: November 2013

Important features of the multivariate approach are discussed, and an extension to this approach is proposed whereby the total uncertainty in site investigation methods due to spatial averaging is assessed prior to its adoption. Results from a site investigation of spatially averaged values of undrained shear strength ([Formula: see text]) and the corresponding coefficient of variation ([Formula: see text]) in Veda sulphide clay were used as a practical illustration of the extended multivariate approach and provide a basis for discussion. The inherent variability and scales of fluctuation for different methods are presented. The study shows the usefulness of the extended multivariate approach for the evaluation of representative values of [Formula: see text] and [Formula: see text] based on results from different methods. It is also a way of implicitly reducing the transformation errors that arise when a property is derived from measurement results. Nevertheless, considerable care must be taken as a much lower COV for one method will have a significant impact on the results.
Effect of carbon nanotube incorporation into polythiophene-fullerene-based organic solar cells
Authors: Skupov Kirill , Adronov Alex
Published: November 2013

The effect of single-walled carbon nanotube (SWNT) incorporation within bulk heterojunction photovoltaic devices based on poly(3-hexylthiophene) − [6,6]-phenyl-C61-butyric acid methyl ester (P3HT−PCBM) (1:1 w/w) active layers was investigated. Both full-length and shortened SWNTs were introduced within the P3HT−PCBM layer at loadings in the range of 0−2 wt%. For full-length SWNTs, it was found that device efficiency decreased at all SWNT loading levels and annealing temperatures, which ranged from 80 to 225 °C. The highest average external efficiencies in the absence of SWNTs reached approximately 2%, while the best efficiencies in devices incorporating the full-length SWNTs only reached 1.3%. When shortened SWNTs were incorporated, device efficiency was unchanged upon annealing at 160 °C (average values of approximately 2%), but the efficiency improved by nearly 50%, relative to controls when devices were annealed at 70 °C. Active layer analysis by grazing incidence X-ray diffraction indicated that nanotubes did not increase polymer crystallinity. Knowing that shortened SWNTs are good hole conductors, it is postulated that the improved device efficiency is due to improved hole transport through the SWNTs in devices where the hole-transporting polymer has not been allowed to adopt its optimal morphology due to underannealing.
Thermodynamic behaviour of microstretch viscoelastic solids with internal heat source
Authors: Deswal Sunita , Yadav Renu
Published: November 2013

The dynamical interactions caused by a line heat source moving inside a homogeneous isotropic thermo-microstretch viscoelastic half space, whose surface is subjected to a thermal load, are investigated. The formulation is in the context of generalized thermoelasticity theories proposed by Lord and Shulman (J. Mech. Phys. Solid, 15, 299 (1967)) and Green and Lindsay (Thermoelasticity, J. Elasticity, 2, 1 (1972)). The surface is assumed to be traction free. The solutions in terms of displacement components, mechanical stresses, temperature, couple stress, and microstress distribution are procured by employing the normal mode analysis. The numerical estimates of the considered variables are obtained for an aluminium–epoxy material. The results obtained are demonstrated graphically to show the effect of moving heat source and viscosity on the displacement, stresses, and temperature distribution.
Infrared spectra of inorganic aerosols: ab initio study of (NH4)2SO4, NH4NO3, and NaNO3
Authors: Bourahla S. , Ali Benamara A. , Kouadri Moustefai S.
Published: November 2013

The structures and vibrational spectra of inorganic aerosols, including ammonium sulfate (NH4)2SO4, ammonium nitrate NH4NO3, and sodium nitrate NaNO3 are investigated at the periodic ab initio quantum mechanical level with the CRYSTAL code, which is based on Gaussian basis sets. Local density (LDA), gradient-corrected (PW91), and hybrid (B3LYP) density functionals have been used and the results are compared with experiment. All three functionals reproduce the equilibrium geometry of these aerosols to a high level of accuracy. The calculations of the frequencies gave a mean absolute deviation from experiment of 3% for B3LYP, clearly showing that this functional performs extremely well in this case. The mean absolute deviation is about 7% and 6% for PW91 and LDA, respectively.
NOISE ANALYSIS AND DESIGN OF CURRENT ACCUMULATOR FOR TDI-CMOS IMAGE SENSOR
Authors: GAO JING , XU JIANGTAO , LUO TAO , GAO CEN
Published: November 2013

The noise of the current accumulator is analyzed. A model of time-delay-integration (TDI) CMOS image sensor is presented, which is used to analyze the noise performance. In this model, input signals are accumulated four times by the type of current and then converted to digital signals to accomplish the other accumulation by 32 times, i.e., 4 × 32 accumulation mode. The noise, which includes switch charge injection, sample noise and kT/C noise, is considered in this model. The major source of the noise and the relationship between noise and sample capacitance are evaluated through the model simulation. The results indicate that the total noise can be restrained by increasing sample capacitance. When the input signal is arranging from 0 μA to 100 μA, the accuracy of the current accumulator can be 11 bits by using 1 pF sample capacitor. The SNR of the output signal can be increased by 20.38 dB which is close to the ideal result. The circuit of the current accumulator based on the model is also proposed.
EXFOLIATION OF GRAPHENE OXIDE NANOSHEETS FROM PENCIL LEAD ANDIN SITUPREPARATION OF GOLD NANOPARTICLES ON GRAPHENE OXIDE NANOSHEETS
Authors: BORUAH SONTARA KONWAR , BORUAH PRABIN KUMAR , SARMA PRADYUT , BEZBARUAH BIPUL , MEDHI CHITRANI , MEDHI OKHIL KUMAR
Published: November 2013

This work reports the low-cost exfoliation of graphene oxide (GO) from pencil lead using modified Hummer's method. The gold nanoparticles ( AuNPs ) supported on GO is prepared via an in situ bio reduction of HAuCl4by polyphenolic biomolecules present in young leaves of tea (Camellia sinensis) extracted in the presence of GO. The UV-Visible absorption spectrum of GO dispersion in water exhibits two bands at 228 nm and a shoulder at ~ 300 nm corresponding to π–π* transitions of aromatic C – C bonds and n–π* transitions of C = O bonds. In photoluminescence (PL) study, GO dispersion in water shows an emission band at 555 nm, when excited at 325 nm. When AuNPs are supported on GO nanosheets the bands at 228 nm and ~ 300 nm of GO disappears and two new UV-Visible bands at 229 nm for π–π* (for C = C ) and 550 nm for transverse surface plasmon resonance (TSPR) of AuNPs appears. When AuNPs are supported on GO nanosheets, PL emission band at 555 nm disappears and two new PL emission bands appear at 431 nm and 658 nm. The physical and morphological characterizations are performed by Fourier-transform infrared (FT-IR), X-ray diffraction (XRD), High-resolution-transmission electron microscopy (HR-TEM) and BET surface area measurement. Morphological studies revealed that the GO nanosheets are well dispersed in water and AuNPs are supported on the GO nanosheets.