bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical Computations for a Nonlinear Free Surface Problem in Shallow Water
Authors: Bai K. J. , Kyoung J. H. , Kim J. W.
Published: March 2009

This paper describes a finite element method applied to a nonlinear free surface flow problem for a ship moving in three dimensions. The physical model is taken to simulate the towing tank experimental conditions. The exact nonlinear free-surface flow problem formulated by an initial/boundary value problem is replaced by an equivalent weak formulation. The same problem was considered earlier by Bai, et. al. [1] where some irregularities were observed in the downstream waves and a transom stern ship geometry could not be treated. In the present paper, specifically, three improvements are made from the earlier work. The first improvement is the introduction of the 5-point Chebyshev filtering scheme which eliminates the irregular and saw-toothed waves in the downstream. The second improvement is that now we can treat a transom stern ship geometry. The third improvement is the introduction of a new boundary condition to simulate a dry bottom behind a transom stern ship which is stretched from the free surface to the bottom at a high Froude number. Computations are made for two models. The first model is tested for the generation of the solitons in the upstream and smooth waves in the downstream. The second model is used to compute the generation of a dry bottom behind a transom stern which is one of highly nonlinear phenomena. The results of the first model show a good agreement with previous results for the generation of the solitons. The results of the second model also show a good agreement with the preliminary experimental observation for a dry-bottom, which will be reported in near future. The numerical simulation of the second model can be applied to the local flow behind a sail of a submarine in cruise, a sloshing problem in LNG tankers, and a dam breaking problem. Both computed models are assumed to be in shallow water for simplicity. However, the present numerical method can treat arbitrary water-depth and practical ship geometries.
Prediction of Green Water and Wave Loading Using a Navier-Stokes Based Simulation Tool
Authors: Kleefsman K. M. Theresa , Fekken Geert , Veldman Arthur E. P. , Bunnik Tim H. J. , Buchner Bas , Iwanowski Bogdan
Published: March 2009

Results of computer simulation of wave and green water loading on floating offshore structures are presented. The simulation program used is a CFD code which solves the Navier-Stokes equations that describe flow of incompressible viscous fluids. The Navier-Stokes equations are discretised using a Finite Volume method on a Cartesian grid with staggered variables. The free surface is displaced using a Volume Of Fluid based algorithm combined with a local height function. In this paper results of validation and sensitivity tests of simulation of green water on the foredeck of an FPSO are presented. Here, the waves are modeled as a dam of water around the deck which is suddenly released. Furthermore, wave loading from impact of regular waves on a SPAR platform is computed and compared with experimental results. The program is found to be robust and the computational results show good agreement with the experiments.
Experiences From Handling Mooring Line Polyester Fibre Ropes During Installation and Retrieval
Authors: Hilmersen Lars
Published: March 2009

The use of fibre ropes made by synthetic fibres have been used more frequent as the offshore industry is moving towards larger water depths. An important aspect is the effect of handling on the large, but delicate, ropes during installation offshore using tools and equipment that easily can destroy the load bearing capacities of the ropes. In order to get hands on experience in the field large polyester ropes have been used as inserts in catenary mooring lines for Mobile Offshore Units (MODU) working on depths ranging from 80 to 350 meters. The ropes have been integrated in the catenary chain mooring lines both in the suspended part and in the bottom part of the mooring leg thus having been exposed to seafloor clay. Subsea buoy have been attached to the ropes using smaller size fibre ropes in order to lift the mooring lines from the seafloor. The paper will detail how the large fibre ropes have been mobilised and demobilised repeatedly from/to storage drums to/from the installation vessel winch drum. During installation and retrieval the fibre ropes have been installed from the vessels winch drum using regular anchor handling equipment and vessels. When the MODU has been moved between locations some ropes have been retrieved to the vessels winch drums while the others have been used to tow and to keep the units station. Samples of the used ropes are taken and is subjected to a test program in the laboratory in order to document the effect of extensive use and handling and exposure to seabed clay.
Wave Statistics for Intermediate Depth Water: New Waves and Symmetry
Authors: Taylor P. H. , Williams B. A.
Published: March 2009

A study has been made into the average shape of large crests and troughs during several storms using wave elevation data from the WACSIS measurement programme. The analysis techniques adopted were data-driven at all times, in order to test whether 2nd order wave theory could reproduce important features in the field data. The sea surface displayed obvious non-linear behaviour, reflected in the fact that the shapes of crests were always sharper and larger than their trough equivalents. Assuming that the dominant non-linear correction is second order in the wave steepness (but without a knowledge of the detailed form of 2nd order theory), the average shapes of maxima in the underlying linear wave components were shown to match NewWave. This NewWave is the scaled auto-correlation function for a linear random process with the same power spectrum as the measured waves. Thus, NewWave was shown to be an acceptable model for the linear part of large waves on intermediate water depth (here ∼17m). Assuming that NewWave is a good model for the linear part of large crests and troughs, a value for the second order coefficient required to estimate crest elevation statistics was derived from the measured data for several storms. This coefficient was in good agreement with the results of the 2nd order random simulations of Forristall and Prevosto. As well as studying vertical asymmetry, required for crest and trough statistics, horizontal asymmetry was examined using the Hilbert transform. Compared to a large amount of vertical asymmetry, the analysis showed that there was virtually no horizontal asymmetry for the bulk of the waves in the records. However, there is a very small degree of horizontal asymmetry exhibited in the largest waves in the records. Thus, given a surface elevation record, it is difficult to distinguish the direction of the time axis, again consistent with most of the non-linearity being due to simple 2nd order bound waves.
Generation of Freak Wave in Non-Uniform Current
Authors: Lavrenov I. V.
Published: March 2009

Accident of freak wave collision with a ship in the Agulhas current is described with appropriate weather conditions and non-uniform current speed distribution. Satellite observation shows an essential wave height enlargements in the current. Using a spectral mathematical model this fact is explained as a result of wind wave and current interaction. Thus, the appearance of freak wave is explained as a result of wind wave transformation in the Agulhas current. Swell is captured and intensified by the counter-current and is directed into the region of the maximum value of the current velocity, as a result there is a great concentration of the wave energy density. The superposition of wind sea with swell transformed by the current promotes formation of the freak waves.
Modern Approaches to Crack Arrest
Authors: Slater Simon
Published: March 2009

In modern day structures fracture initiation cannot be excluded in an absolute sense, defects may exist that when subjected to the operating stress may form brittle propagating cracks. In such cases an assessment of the crack arrest capability of the steel may be required to ensure structural integrity. This paper aims to give a review of existing crack arrest assessment procedures discussing their respective advantages and limitations. In addition a number of modern approaches currently being developed will be introduced and their capabilities compared to existing procedures.
Design for Safety of Large Marine Engineering Products
Authors: Wang J. , Sii H. S. , Pillay A. , Saajedi A. , Yang J. B. , Liu J.
Published: March 2009

As maritime engineering products become more and more complex and the public concern regarding their safety increases, design for safety has attracted more and more attention in the marine and offshore industries. This paper reviews the current practices in risk assessment employed in the marine and offshore industries. The issues in risk assessment of large maritime engineering products are highlighted. A design for safety methodology is described together with the typical supporting risk assessment techniques. Several novel safety modelling and decision making techniques are outlined. Examples are used to demonstrate two novel risk modelling and decision making tools described with an aim of providing safety engineers with an opportunity to appreciate the novel approaches.
Detached-Eddy Simulation of Flow Around the NREL Phase-VI Blade
Authors: Johansen J. , So̸rensen N. N. , Michelsen J. A. , Schreck S.
Published: March 2009

The Detached-Eddy Simulation model implemented in the computational fluid dynamics code, EllipSys3D, is applied on the flow around the NREL Phase-VI wind turbine blade. Results are presented for flow around a parked blade at fixed angle of attack and a blade pitching along the blade axis. Computed blade characteristics are compared with experimental data from the NREL/NASA Ames Phase-VI unsteady experiment. The Detached-Eddy Simulation model is a method for predicting turbulence in computational fluid dynamics computations, which combines a Reynolds Averaged Navier-Stokes method in the boundary layer with a Large Eddy Simulation in the free shear flow. The present study focuses on static and dynamic stall regions highly relevant for stall regulated wind turbines. Computations do predict force coefficients and pressure distributions fairly good and results using Detached-Eddy Simulation show considerably more three-dimensional flow structures compared to conventional two-equation Reynolds Averaged Navier-Stokes turbulence models, but no particular improvements are seen on the global blade characteristics.
Release from speech-on-speech masking in a front-and-back geometry
Authors: Aaronson Neil L. , Rakerd Brad , Hartmann William M.
Published: March 2009

Informational masking of a target female talker by female distracters was measured with target and distracters presented from directly in front of the listener as a baseline condition. Next, it was found that if the distracters were also presented from directly in back of the listener, advanced or delayed by a few milliseconds with respect to the distracters in front, release from informational masking occurred. Release from informational masking was found for all delays within the Haas region of ±50ms, with peak release of about 3.5dB. This peak occurred for a delay of ±2ms and it was shown to be the result of delay-and-add filtering. Release from energetic masking was also found, but only for delays of ±0.5ms or less.
Low-frequency speech cues and simulated electric-acoustic hearing
Authors: Brown Christopher A. , Bacon Sid P.
Published: March 2009

The addition of low-frequency acoustic information to real or simulated electric stimulation (so-called electric-acoustic stimulation or EAS) often results in large improvements in intelligibility, particularly in competing backgrounds. This may reflect the availability of fundamental frequency (F0) information in the acoustic region. The contributions of F0 and the amplitude envelope (as well as voicing) of speech to simulated EAS was examined by replacing the low-frequency speech with a tone that was modulated in frequency to track the F0 of the speech, in amplitude with the envelope of the low-frequency speech, or both. A four-channel vocoder simulated electric hearing. Significant benefit over vocoder alone was observed with the addition of a tone carrying F0 or envelope cues, and both cues combined typically provided significantly more benefit than either alone. The intelligibility improvement over vocoder was between 24 and 57 percentage points, and was unaffected by the presence of a tone carrying these cues from a background talker. These results confirm the importance of the F0 of target speech for EAS (in simulation). They indicate that significant benefit can be provided by a tone carrying F0 and amplitude envelope cues. The results support a glimpsing account of EAS and argue against segregation.
Flow-structure-acoustic interaction in a human voice model
Authors: Becker Stefan , Kniesburges Stefan , Müller Stefan , Delgado Antonio , Link Gerhard , Kaltenbacher Manfred , Döllinger Michael
Published: March 2009

For the investigation of the physical processes of human phonation, inhomogeneous synthetic vocal folds were developed to represent the full fluid-structure-acoustic coupling. They consisted of polyurethane rubber with a stiffness in the range of human vocal folds and were mounted in a channel, shaped like the vocal tract in the supraglottal region. This test facility permitted extensive observations of flow-induced vocal fold vibrations, the periodic flow field, and the acoustic signals in the far field of the channel. Detailed measurements were performed applying particle-image velocimetry, a laser-scanning vibrometer, a microphone, unsteady pressure sensors, and a hot-wire probe, with the aim of identifying the physical mechanisms in human phonation. The results support the existence of the Coanda effect during phonation, with the flow attaching to one vocal fold and separating from the other. This behavior is not linked to one vocal fold and changes stochastically from cycle to cycle. The oscillating flow field generates a tonal sound. The broadband noise is presumed to be caused by the interaction of the asymmetric flow with the downstream-facing surfaces of the vocal folds, analogous to trailing-edge noise.
Stochastic properties of auditory brainstem coincidence detectors in binaural perception
Authors: Krips Ram , Furst Miriam
Published: March 2009

In the mammalian auditory brainstem, two types of coincidence detector cells are involved in binaural localization: excitatory-excitatory (EE) and excitatory-inhibitory (EI). Using statistics derived from EE and EI spike trains, binaural discrimination abilities of single tones were predicted. The minimum audible angle (MAA), as well as the just noticeable difference of interaural time delay (ITD) and interaural level difference (ILD) were analytically derived for both EE and EI cells on the basis of two possible neural coding patterns, rate coding that ignores a spike’s timing information and all-information coding (AIN), which considers a spike’s timing occurrences. Simulation results for levels below saturation were qualitatively compared to experimental data, which yielded the following conclusions: (1) ITD is primarily estimated by EE cells with AIN coding when the ipsilateral auditory input exhibits phase delay between 40° and 65°. (2) In ILD, both AIN and rate coding provide identical performances. It is most likely that ILD is primarily estimated by EI cells according to rate coding, and for ILD the information derived from the spikes’ timing is redundant. (3) For MAA estimation, the derivation should take into account ambiguous directions of a source signal in addition to its true value.
On the applicability of the spherical wave expansion with a single origin for near-field acoustical holography
Authors: Gomes Jesper , Hald Jørgen , Juhl Peter , Jacobsen Finn
Published: March 2009

The spherical wave expansion with a single origin is sometimes used in connection with near-field acoustical holography to determine the sound field on the surface of a source. The radiated field is approximated by a truncated expansion, and the expansion coefficients are determined by matching the sound field model to the measured pressure close to the source. This problem is ill posed, and therefore regularization is required. The present paper investigates the consequence of using only the expansion truncation as regularization approach and compares it with results obtained when additional regularization (the truncated singular value decomposition) is introduced. Important differences between applying the method when using a microphone array surrounding the source completely and an array covering only a part of the source are described. Another relevant issue is the scaling of the wave functions. It is shown that it is important for the additional regularization to work properly that the wave functions are scaled in such a way that their magnitude on the measurement surface decreases with the order. Finally, the method is applied on nonspherical sources using a vibrating plate in both simulations and an experiment, and the performance is compared with the equivalent source method.
Geographic variation in Northwest Atlantic fin whale (Balaenoptera physalus) song: Implications for stock structure assessment
Authors: Delarue Julien , Todd Sean K. , Van Parijs Sofie M. , Di Iorio Lucia
Published: March 2009

Passive acoustic data are increasingly being used as a tool for helping to define marine mammal populations and stocks. Fin whale (Balaenoptera physalus) songs present a unique opportunity to determine interstock differences. Their highly stereotyped interpulse interval has been shown to vary between geographic areas and to remain stable over time in some areas. In this study the structure of songs recorded at two geographically close feeding aggregations in the Gulf of St. Lawrence (GSL) and Gulf of Maine (GoM) was compared. Recordings were made from September 2005 through February 2006 in the GSL and intermittently between January 2006 and September 2007 at two locations in the GoM. 6257 pulse intervals corresponding to 19 GSL and 29 GoM songs were measured to characterize songs from both areas. Classification trees showed that GSL songs differ significantly from those in the GoM. The results are consistent with those derived from other stock structure assessment methodologies, such as chemical signature and photoidentification analysis, suggesting that fin whales in these areas may form separate management stocks. Song structure analysis could therefore provide a useful and cost-efficient tool for defining conservation units over temporal and geographical scales relevant to management objectives in fin whales.
Manatee (Trichechus manatus) vocalization usage in relation to environmental noise levels
Authors: Miksis-Olds Jennifer L. , Tyack Peter L.
Published: March 2009

Noise can interfere with acoustic communication by masking signals that contain biologically important information. Communication theory recognizes several ways a sender can modify its acoustic signal to compensate for noise, including increasing the source level of a signal, its repetition, its duration, shifting frequency outside that of the noise band, or shifting the timing of signal emission outside of noise periods. The extent to which animals would be expected to use these compensation mechanisms depends on the benefit of successful communication, risk of failure, and the cost of compensation. Here we study whether a coastal marine mammal, the manatee, can modify vocalizations as a function of behavioral context and ambient noise level. To investigate whether and how manatees modify their vocalizations, natural vocalization usage and structure were examined in terms of vocalization rate, duration, frequency, and source level. Vocalizations were classified into two call types, chirps and squeaks, which were analyzed independently. In conditions of elevated noise levels, call rates decreased during feeding and social behaviors, and the duration of each call type was differently influenced by the presence of calves. These results suggest that ambient noise levels do have a detectable effect on manatee communication and that manatees modify their vocalizations as a function of noise in specific behavioral contexts.
An in situ calibration for hearing thresholds
Authors: Withnell Robert H. , Jeng Patricia S. , Waldvogel Kelly , Morgenstein Kari , Allen Jont B.
Published: March 2009

Quantifying how the sound delivered to the ear canal relates to hearing threshold has historically relied on acoustic calibration in physical assemblies with an input impedance intended to match the human ear (e.g., a Zwislocki coupler). The variation in the input impedance of the human ear makes such a method of calibration questionable. It is preferable to calibrate the acoustic signal in each ear individually. By using a calibrated sound source and microphone, the acoustic input impedance of the ear can be determined, and the sound delivered to the ear calibrated in terms of either (i) the incident sound pressure wave or (ii) that portion of the incident sound pressure wave transmitted to the middle ear and cochlea. Hearing thresholds expressed in terms of these quantities are reported, these in situ calibrations not being confounded by ear canal standing waves. Either would serve as a suitable replacement for the current practice of hearing thresholds expressed in terms of sound pressure level calibrated in a 6cc or 2cc coupler.
Acoustic microstreaming around an isolated encapsulated microbubble
Authors: Liu Xiaozhou , Wu Junru
Published: March 2009

An analytical theory has been developed to calculate microstreaming velocity inside and outside an encapsulated microbubble (EMB) in a viscous liquid produced by its oscillations driven by an ultrasound field, taking account of two predominant modes of the EMB’s motion: a monopole (pulsation) and a dipole (translational harmonic vibrations). Analytical expressions of radial as well as tangential stresses are derived near the shell of the EMB. Numerical calculations in parameter regimes applicable to sonoporation are presented. For the calculation the following parameters unless specified otherwise are used: f=1 MHz, r0=2 μm, κ=1.4, ρL=1000 kg/m3, ρs=1100 kg/m3, P0=100 kPa, μs=0.05 Pa s, μL=0.001 Pa s, σ1=0.04 N/m, σ2=0.005 N/m, and Gs=15 MPa. The calculated results show that the streaming velocity and stresses near an EMB are functions of the mechanical properties of shell and gas. Overall, the streaming velocity and stresses for an EMB are found to be greater than those for a similar size free bubble under the same ultrasound excitation. This finding is consistent with the existing theory of acoustic streaming of an oscillating bubble near a boundary given by Nyborg (1958) [J. Acoust. Soc. Am. 30, 329–339].
Modeling the effect of channel number and interaction on consonant recognition in a cochlear implant peak-picking strategy
Authors: Verschuur Carl
Published: March 2009

Difficulties in speech recognition experienced by cochlear implant users may be attributed both to information loss caused by signal processing and to information loss associated with the interface between the electrode array and auditory nervous system, including cross-channel interaction. The objective of the work reported here was to attempt to partial out the relative contribution of these different factors to consonant recognition. This was achieved by comparing patterns of consonant feature recognition as a function of channel number and presence/absence of background noise in users of the Nucleus 24 device with normal hearing subjects listening to acoustic models that mimicked processing of that device. Additionally, in the acoustic model experiment, a simulation of cross-channel spread of excitation, or “channel interaction,” was varied. Results showed that acoustic model experiments were highly correlated with patterns of performance in better-performing cochlear implant users. Deficits to consonant recognition in this subgroup could be attributed to cochlear implant processing, whereas channel interaction played a much smaller role in determining performance errors. The study also showed that large changes to channel number in the Advanced Combination Encoder signal processing strategy led to no substantial changes in performance.
Ray-based description of normal modes in a deep ocean acoustic waveguide
Authors: Virovlyansky A. L. , Kazarova A. Yu. , Lyubavin L. Ya.
Published: March 2009

Modal structure of the wave field in a deep ocean environment with sound speed fluctuations induced by random internal waves is considered. An approximate analytical description of the modal structure at megameter ranges is derived by combining two known results: (i) relations expressing mode amplitudes through parameters of ray paths and (ii) stochastic ray theory. For a monochromatic wave field, a simple analytical estimate has been obtained for a coarse-grained distribution of acoustic energy between normal modes. Significant attention has been paid to the investigation of the mode pulses, that is, sound pulses carried by individual modes. Analytical estimates for the spread of mode pulse and bias of its mean travel time in the presence of internal waves are derived.
Analytical and experimental investigation on transmission loss of clamped double panels: Implication of boundary effects
Authors: Xin F. X. , Lu T. J.
Published: March 2009

The air-borne sound insulation performance of a rectangular double-panel partition clamp mounted on an infinite acoustic rigid baffle is investigated both analytically and experimentally and compared with that of a simply supported one. With the clamped (or simply supported) boundary accounted for by using the method of modal function, a double series solution for the sound transmission loss (STL) of the structure is obtained by employing the weighted residual (Galerkin) method. Experimental measurements with Al double-panel partitions having air cavity are subsequently carried out to validate the theoretical model for both types of the boundary condition, and good overall agreement is achieved. A consistency check of the two different models (based separately on clamped modal function and simply supported modal function) is performed by extending the panel dimensions to infinite where no boundaries exist. The significant discrepancies between the two different boundary conditions are demonstrated in terms of the STL versus frequency plots as well as the panel deflection mode shapes.
An analytical model for turbulence scattered rays in the shadow zone for outdoor sound propagation calculation
Authors: Lam Yiu Wai
Published: March 2009

In outdoor sound propagation, an inherent problem of the ray tracing method is its inability to determine the sound pressure level in the shadow zone, where geometrical rays do not penetrate. This is a serious problem in a turbulent atmosphere where significant sound energy will be scattered into the shadow. Empirical corrections that are determined from measurements or numerical simulations are limited to situations within the bounds of the empirical corrections. This paper describes a different approach where the ray tracing model is modified analytically into a scattered ray model. Rays are first diffracted from the shadow boundary, which is determined by the geometrical ray paths. The diffracted rays are then scattered by turbulence in their way to the receiver. The amount of scatter is determined from turbulence statistics that are determined from a Gaussian turbulence model. Most of the statistics are determined analytically except one element, which is determined empirically from numerical simulations. This turbulence scattered ray model is shown to have good accuracy against calculations based on the parabolic equation, and against previously published measurement data. It was found that the agreement is good both with and without turbulence, at distance up to 2km from the shadow boundary.
Comparison of the Levels of Immunogenicity and Safety of Zostavax in Adults 50 to 59 Years Old and in Adults 60 Years Old or Older
Authors: Sutradhar Santosh C. , Wang William W. B. , Schlienger Katia , Stek Jon E. , Xu Jin , Chan Ivan S. F. , Silber Jeffrey L.
Published: March 2009

Zostavax has been shown to be efficacious in the prevention of herpes zoster and generally well tolerated in clinical trials among subjects 60 years old or older. This prespecified combined analysis from two studies compares the levels of immunogenicity and safety of Zostavax in subjects 50 to 59 years old versus those in subjects ≥60 years old. Varicella-zoster virus (VZV) antibody (Ab) titers were measured by glycoprotein enzyme-linked immunosorbent assay at baseline and 4 weeks postvaccination. Noninferiority was evaluated by estimated geometric mean severalfold rise (GMFR) ratio (50 to 59 years old/≥60 years old) and two-sided 95% confidence interval (CI). Success was defined by a lower bound (LB) of the 95% CI of the GMFR ratio of >0.67. Acceptability of postvaccination VZV Ab was defined by an LB of the 95% CI of the GMFR of >1.4. Safety data were recorded for 28 days postvaccination by standardized vaccination report card. The estimated GMFRs from baseline to 4 weeks postvaccination were 2.6 (95% CI, 2.4, 2.9) in subjects 50 to 59 years old and 2.3 (95% CI, 2.1, 2.4) in subjects ≥60 years old. The estimated GMFR ratio (50 to 59 years old/≥60 years old) was 1.13 (95% CI, 1.02, 1.25). No serious Zostavax-related adverse experiences were reported. After a dose of Zostavax, the GMFR of the VZV Ab response in subjects 50 to 59 years old was noninferior to that in subjects ≥60 years old. The VZV Ab response was acceptable in both age groups. Zostavax was generally well tolerated in both age groups.
Protective Immunity in Mice Achieved with Dry Powder Formulation and Alternative Delivery of Plague F1-V Vaccine
Authors: Huang Joanne , D'Souza Ajit J. , Alarcon Jason B. , Mikszta John A. , Ford Brandi M. , Ferriter Matthew S. , Evans Michelle , Stewart Todd , Amemiya Kei , Ulrich Robert G. , Sullivan Vincent J.
Published: March 2009

The potential use of
Yersinia pestis
as a bioterror agent is a great concern. Development of a stable powder vaccine against
Y. pestis
and administration of the vaccine by minimally invasive methods could provide an alternative to the traditional liquid formulation and intramuscular injection. We evaluated a spray-freeze-dried powder vaccine containing a recombinant F1-V fusion protein of
Y. pestis
for vaccination against plaque in a mouse model. Mice were immunized with reconstituted spray-freeze-dried F1-V powder via intramuscular injection, microneedle-based intradermal delivery, or noninvasive intranasal administration. By intramuscular injection, the reconstituted powder induced serum antibody responses and provided protection against lethal subcutaneous challenge with 1,000 50% lethal doses of
Y. pestis
at levels equivalent to those elicited by unprocessed liquid formulations (70 to 90% protection). The feasibility of intradermal and intranasal delivery of reconstituted powder F1-V vaccine was also demonstrated. Overall, microneedle-based intradermal delivery was shown to be similar in efficacy to intramuscular injection, while intranasal administration required an extra dose of vaccine to achieve similar protection. In addition, the results suggest that seroconversion against F1 may be a better predictor of protection against
Y. pestis
challenge than seroconversion against either F1-V or V. In summary, we demonstrate the preclinical feasibility of using a reconstituted powder F1-V formulation and microneedle-based intradermal delivery to provide protective immunity against plague in a mouse model. Intranasal delivery, while feasible, was less effective than injection in this study. The potential use of these alternative delivery methods and a powder vaccine formulation may result in substantial health and economic benefits.
Clinical and Molecular Epidemiology of Human Parainfluenza Virus 4 Infections in Hong Kong: Subtype 4B as Common as Subtype 4A
Authors: Lau Susanna K. P. , Li Kenneth S. M. , Chau Kam-yu , So Lok-yee , Lee Rodney A. , Lau Yu-lung , Chan Kwok-hung , Lim Wilina W. L. , Woo Patrick C. Y. , Yuen Kwok-yung
Published: March 2009

In this 1-year study, 35 (1.2%) of 2,912 nasopharyngeal aspirates were positive for human parainfluenza virus 4 (HPIV4) by reverse transcription-PCR. Patients with HPIV4 infection were mainly young children and immunocompromised adults. In contrast to the reported predominance of HPIV4A infection, molecular subtyping revealed that 15 (44%) cases were caused by HPIV4B.
Pilot Study of Association of Bacteria on Breast Implants with Capsular Contracture
Authors: Del Pozo Jose L. , Tran Nho V. , Petty Paul M. , Johnson Craig H. , Walsh Molly F. , Bite Uldis , Clay Ricky P. , Mandrekar Jayawant N. , Piper Kerryl E. , Steckelberg James M. , Patel Robin
Published: March 2009

Capsular contracture is the most common and frustrating complication in women who have undergone breast implantation. Its cause and, accordingly, treatment and prevention remain to be elucidated fully. The aim of this prospective observational pilot study was to test the hypothesis that the presence of bacteria on breast implants is associated with capsular contracture. We prospectively studied consecutive patients who underwent breast implant removal for reasons other than overt infection at the Mayo Clinic from February through September 2008. Removed breast implants were processed using a vortexing/sonication procedure and then subjected to semiquantitative culture. Twenty-seven of the 45 implants collected were removed due to significant capsular contracture, among which 9 (33%) had ≥20 CFU bacteria/10 ml sonicate fluid; 18 were removed for reasons other than significant capsular contracture, among which 1 (5%) had ≥20 CFU/10 ml sonicate fluid (
P
= 0.034).
Propionibacterium
species, coagulase-negative staphylococci, and
Corynebacterium
species were the microorganisms isolated. The results of this study demonstrate that there is a significant association between capsular contracture and the presence of bacteria on the implant. The role of these bacteria in the pathogenesis of capsular contracture deserves further study.
Staphylococcal Interspersed Repeat Unit Typing of
Staphylococcus aureus
: Evaluation of a New Multilocus Variable-Number Tandem-Repeat Analysis Typing Method
Authors: Conceição Teresa , Aires de Sousa Marta , de Lencastre Hermínia
Published: March 2009

The present study evaluates the performance of the staphylococcal interspersed repeat unit (SIRU) method applied to a diverse collection of 104
Staphylococcus aureus
isolates previously characterized by pulsed-field gel electrophoresis (PFGE),
spa
typing, multilocus sequence typing (MLST), and staphylococcal cassette chromosome
mec
typing for methicillin-resistant
S. aureus
. The SIRU method distributed the 104 strains into 81 SIRU profiles that could be clustered into 12 groups and 29 singletons. The discriminatory power of the method at the profile level, translated by Simpson's index of diversity (SID), was similar to that of PFGE subtyping (SID = 99.23% versus 99.85%) and slightly higher than that of
spa
typing (SID = 97.61%). At the group level, the SIRU SID (93.24%) was lower than that of PFGE typing (95.41%) but higher than that of MLST (SID = 91.77%). The adjusted Rand (AR) coefficient showed that SIRU typing at the group level had the highest congruence with MLST (AR = 0.5736) and with clonal complex (CC) (AR = 0.4963) but the lowest congruence with PFGE subtype (AR = 0.0242). The Wallace coefficient indicated that in the present collection, two strains with the same SIRU profile have a 100% probability of belonging to the same CC, a 90% probability of sharing the same
spa
type, and an 83% probability of being classified in the same sequence type. The high discriminatory power of the SIRU method, along with its apparent concordance with MLST results, makes it potentially valuable for
S. aureus
short-term epidemiological investigations and population dynamics as well.
Analysis Identifying Common and Distinct Sequences among Texas Clinical Strains of
Mycoplasma genitalium
Authors: Musatovova Oxana , Baseman Joel B.
Published: March 2009

Mycoplasma genitalium
is a human bacterial pathogen linked to urethritis and other sexually transmitted diseases. Here, we assessed the incidence of
M. genitalium
infection in patients attending a sexually transmitted disease clinic in San Antonio, TX, by use of diagnostic real-time PCR. Overall, 16.8% of women and 15.1% of men were found
M. genitalium
positive. Regions of the
mgpB
gene, which encodes the MgPa adhesin, were amplified from positive clinical specimens and evaluated for sequence variability, which demonstrated transmission of the pathogen between sexual partners. Follow-up analysis of a subset of patient specimens revealed reinfection by a different strain of
M. genitalium
, indicating the absence of protective immunity. Eighteen DNA sequence variants were obtained and compared with all other available clinical sequences. Detailed analysis revealed silent mutations of six amino acid residues within the encoded region of the MgPa adhesin in numerous clinical strains. In addition, missense mutations of limited numbers of amino acids were observed. Alignment of putative amino acid sequences revealed the simultaneous occurrence of several mutations and the existence of identical or similar protein variants in strains from different locations.
High Frequency and Diversity of Rearrangements in Polyomavirus BK Noncoding Regulatory Regions Cloned from Urine and Plasma of Israeli Renal Transplant Patients and Evidence for a New Genetic Subtype
Authors: Perets Tsachi Tsadok , Silberstein Ilana , Rubinov Jana , Sarid Ronit , Mendelson Ella , Shulman Lester M.
Published: March 2009

Polyomavirus BK (BKV) establishes latent infection in various human tissues, including the kidney. Reactivation following renal transplantation (RT) may cause BKV-associated nephropathy, leading to graft loss. BKV reactivation is often associated with extensive rearrangements in the BKV noncoding regulatory region (NCRR). We explored the formation and predominance of the rearrangements versus the diversity of the rearrangements by cloning and characterizing PCR-amplified NCRR sequences from six Israeli RT patients. We found a high frequency and a high degree of diversity of rearrangements: NCRRs that contained major rearrangements (mrNCRRs), including large insertions and deletions, were detected in 0 to 100% of the clones from individual samples (mean, 50% and 67% in plasma and urine, respectively). In addition, we found a high frequency of mrNCRRs that contained single-nucleotide variations (snvNCRRs) among identical mrNCRRs and archetype clones. mrNCRRs were present in plasma and in concomitantly collected urine samples, but for each patient, only a subset of the mrNCRRs and snvNCRRs were present in both compartments at the same time and/or in subsequent samples from the same compartment. Some mrNCRRs were observed over several months, indicating the continuous replication of the viral genomes carrying them. Phylogenetic analysis based on the snvNCRR in the archetype clones grouped isolates from four of the patients into a new subgroup of genotype IV. Genotypes Ib-1 and Ib-2 were also found. Isolates from two patients had NCRRs from two genotypes, one concurrently with a RT and one after a second RT. Our study prompts further investigation of the functional consequences of NCRR rearrangements to assess their biological significance and their putative role in disease progression and prognosis.
“
Mycobacterium tilburgii
,” a Newly Described, Uncultivated Opportunistic Pathogen
Authors: Palmore Tara N. , Shea Yvonne R. , Conville Patricia S. , Witebsky Frank G. , Anderson Victoria L. , Rupp Hodge Irene P. , Holland Steven M.
Published: March 2009

Molecular methods are increasingly used to identify pathogens that are difficult to cultivate. We report a case of disseminated infection with “
Mycobacterium tilburgii
,” a proposed species that has never been cultivated. The case illustrates the diagnostic utility of sequence analysis of the 16S rRNA gene directly from clinical specimens.
Oseltamivir-Resistant Influenza A Viruses Circulating in Japan
Authors: Tamura Daisuke , Mitamura Keiko , Yamazaki Masahiko , Fujino Motoko , Nirasawa Mari , Kimura Kazuhiro , Kiso Maki , Shimizu Hideaki , Kawakami Chiharu , Hiroi Satoshi , Takahashi Kazuro , Hata Mami , Minagawa Hiroko , Kimura Yoshiaki , Kaneda Satoko , Sugita Shigeo , Horimoto Taisuke , Sugaya Norio , Kawaoka Yoshihiro
Published: March 2009

Surveillance studies of the influenza viruses circulating in Europe and other countries in 2007 and 2008 have revealed rates of resistance to oseltamivir of up to 67% among H1N1 viruses. In the present study, we examined 202 clinical samples obtained from patients infected with H1N1 virus in Japan in 2007 and 2008 for oseltamivir resistance and found that three were oseltamivir resistant (1.5%). The 50% inhibitory concentrations (IC
50
s), as measured by a sialidase inhibition assay with these drug-resistant viruses, were >100-fold higher than those of the nonresistant viruses (median IC
50
, 12.6 nmol/liter). The His274Tyr (strain N2 numbering) mutation of the neuraminidase protein, which is known to confer oseltamivir resistance, was detected in these three isolates. Phylogenetic analysis showed that one virus belonged to a lineage that is composed of drug-resistant viruses isolated in Europe and North America and that the other two viruses independently emerged in Japan. Continued surveillance studies are necessary to observe whether these viruses will persist.
Associative learning, short-term memory, and colour preference during first feeding by juvenile Atlantic salmon
Authors: Clarke L. A. , Sutterlin A. M.
Published: March 2009

The innate colour preference of 51 groups of 20 fry was examined at resorption of the visible yolk sac. A mixture of equal portions of blue, red, green, yellow, and unstained cod or capeling eggs were given to fry for 10-min feeding intervals after which fry stomach contents were examined and numbers of each colour of egg consumed were tabulated. Fry showed innate colour preference for red eggs; however, this could be changed to any other colour by only one previous feeding with eggs of the desired colour. This single-trial learning was retained up to 6 h after feeding but began to deteriorate after 21 h. Posisble applications in early rearing of Atlantic salmon fry in hatcheries are discussed.
Temperature tolerance, salinity tolerance, osmoregulation, and water permeability of arctic marine isopods of the Mesidotea (=Saduria) complex
Authors: Percy J. A.
Published: March 2009

Temperature tolerance, salinity tolerance, osmoregulation, and integumental water permeability have been studied in three arctic marine isopods of the Mesidotea complex, as well as in a freshwater variant of Mesidotea entomon. Temperature has little influence on their distribution in the southern Beaufort Sea. Habitat temperatures are far below the 96 h tolerance limits of the species which range from 21.5 to 26.3 °C. Salinity is an important factor in their distribution. The relative salinity tolerances and osmoregulatory capabilities of the isopods correlate well with their distribution in coastal waters. The marine M. entomon could not be adapted to fresh water even by a 7-week, stepwise transfer. The freshwater form, however, survives indefinitely in undiluted seawater. In all three species, the haemolymph is hyperosmotic in dilute seawater and isosmotic at higher salinities. Mesidotea entomon is the most effective osmoregulator and Mesidotea sabini is the least effective. All three species reduce their integumental permeability as the salinity falls. The capacity to alter the permeability to water increases in proportion to the euryhalinity of the species. The permeability varies directly with temperature, with Q10 coefficients ranging from 1.75 to 2.68.
A model of foraging efficiency and daily energy budget in the Black Skimmer (Rynchops nigra)
Authors: Blake R. W.
Published: March 2009

A model of the energetics of foraging in the Black Skimmer (Rynchops nigra) is developed. The energy costs of flight and other activities are equated with the energy income from food. The model focuses on the influence of ground proximity during flight (ground effect) on the form of the velocity–power curves of the bird. Minimum power and maximum range speeds are reduced in ground effect but their relative values are unchanged. With increasing ground proximity, foraging efficiency (power input from food divided by flight power) for a given flight velocity increases, but maximal values of foraging efficiency occur at lower speeds. Peak values of foraging efficiency coincide with the position of the maximum range speed on the velocity–power curve. However, maximum values of the daily energy budget parameter (energy income from food divided by the energy cost of flight and of other activiites) occur at greater speeds. If the net daily energy surplus is to be maximized, the bird should fly at speeds greater than that for maximum range. Ground effect reduces the minimum food intake to ensure a nonnegative daily energy budget for any given foraging time. The foraging radius attainable on a given energy store is significantly increased in ground effect. Calculated foraging radii for a modest energy surplus exceed observed values. The energy budget of a breeding bird and the possible constraints on breeding are considered. It is concluded that the energy required to produce the eggs is not a major limitation. Model results are discussed in relation to observations of flight behaviour.
Lack of immunological privilege in chick brain as a transplantation site
Authors: Clements L. G. , Stewart P. A.
Published: March 2009

To determine if the chick brain is an immunologically privileged site, skin autografts, allografts, and xenografts were transplanted into the brain of chicks (Gallus domesticus) and the rate of rejection of the grafts was compared with that of skin autografts, allografts, and xenografts transplanted to orthotopic sites. Rejection of the orthotopic grafts was evaluated by microscopic examination to determine the presence of the histological features of rejection. Grafts in the brain were examined microscopically for the histological features of rejection. Autografts were found to survive in the brain and on the skin for at least 4 weeks. However, when allografts and xenografts were transplanted into the brain, they were rejected just as quickly as when they were transplanted to the skin. The median survival time was 7 1/2 days for allografts to the brain and 8 1/2 days for orthotopic allografts. The median survival time was approximately 6 1/2 days for orthotopic xenografts and 7 days for xenografts to the brain. In the chick, then, the brain is not an immunologically privileged site.