bluuebunny/crossref_metadata_2025 huggingface dataset:
Technical and Economic Evaluation of IGCC Systems Using Coal and Petroleum Coke Considering the Brazilian Scenario
Authors: Silva Ortiz Pablo Andrés , Venturini Osvaldo José , Silva Lora Electo Eduardo
Published: May 2012

The increasing trend in global production of petroleum coke (petcoke) is the result of their multiple and innovative industrial applications. From this point of view and also considering the current situation of the traditional energy reserves worldwide, it is important to conduct studies in this area through analysis of the main components of the power plants utilizing this fuel (petcoke). The main target of this study is to realize a techno-economic evaluation of IGCC (Integrated Gasification Combined Cycle) technology, using Brazilian coal, petcoke and a mix of 50% coal and 50% petcoke as fuel. In this paper, the gasification process and the combined cycle are analyzed, considering the implementation of the IGCC technology in the Termobahia power plant. Termobahia is a cogeneration combined cycle power plant, located in the Brazilian state of Bahia that produces 190 MW of electricity and 350 ton/h of steam. The steam produced is sold to an oil refinery (RLAM) located next to it. In first part of this work, the production of the synthesis gas (syngas) from coal gasification was simulated using CeSFaMBi™ software. In the next part, the syngas produced is used to analyze the power plant performance through GateCycle™ software. Finally, the obtained operational and economic parameters are compared with the actual operational parameters of the Termobahia power plant in terms of costs, fuel substitution and combined cycle performance variables, as net power, global efficiency and heat rate.
Stability of Flexible Rotors With a LeBlanc Balancer
Authors: Urbiola-Soto Leonardo , Lopez-Parra Marcelo
Published: May 2012

Although the liquid balancer has nearly a century of having been introduced by LeBlanc, little information is available on the dynamic response and stability behavior of this kind of device. Earlier author’s research using a high-speed camera and a Particle Image Velocimetry (PIV) technique showed the existence of a fluid backward traveling wave inside the balancer cavity. This damping phenomenon helps enhance the unbalance response of the rotating system and also raises the stability limits. This paper shows that a flexible rotor employing a LeBlanc balancer has remarkable increase in the threshold speed of instability for aerodynamic cross-coupling and viscous internal friction damping.
Forced Response Prediction for Steam Turbine Last Stage Blade Subject to Low Engine Order Excitation
Authors: Zhou Bin , Mujezinovic Amir , Coleman Andrew , Ning Wei , Ansari Asif
Published: May 2012

Low Engine Order (LEO) excitations on a steam turbine Last Stage low-pressure (LP) Bucket (or Blade) (LSB) are largely the result of flow unsteadiness (e.g. flow circulation and reversal) due to low steam exit velocity (Vax) off the LSB at the off-design conditions. These excitations at low frequencies impose major constraints on LP bucket aeromechanical design. In this study, bucket forced response under typical LEO excitation was analytically predicted and correlated to experimental measurements. First, transient CFD analyses were performed at typical low flow, low Vax operating conditions that had been previously tested in a subscale low pressure turbine test rig. The unsteady pressure distribution on the bucket was derived from the transient CFD analyses at frequencies corresponding to the bucket’s modes of vibration. Subsequently, these computed unsteady pressure were mapped onto a LSB finite element model, and forced response analyses were performed to estimate the bucket dynamic response, i.e. the alternating stresses and strains. The analytically predicted bucket response was compared against measured data from airfoil mounted strain gages and good correlation was found between the analytical prediction and the test data. Despite uncertainty associated with various parameters such as damping and unsteady steam forcing etc., the developed methodology provides a viable approach for predicting bucket forced response and in turn High Cycle Fatigue (HCF) capability during early phases of steam turbine LSB design.
Range compensation for backscattering measurements in the difference-frequency nearfield of a parametric sonar
Authors: Foote Kenneth G.
Published: May 2012

Measurement of acoustic backscattering properties of targets requires removal of the range dependence of echoes. This process is called range compensation. For conventional sonars making measurements in the transducer farfield, the compensation removes effects of geometrical spreading and absorption. For parametric sonars consisting of a parametric acoustic transmitter and a conventional-sonar receiver, two additional range dependences require compensation when making measurements in the nonlinearly generated difference-frequency nearfield: an apparently increasing source level and a changing beamwidth. General expressions are derived for range compensation functions in the difference-frequency nearfield of parametric sonars. These are evaluated numerically for a parametric sonar whose difference-frequency band, effectively 1–6 kHz, is being used to observe Atlantic herring (Clupea harengus) in situ. Range compensation functions for this sonar are compared with corresponding functions for conventional sonars for the cases of single and multiple scatterers. Dependences of these range compensation functions on the parametric sonar transducer shape, size, acoustic power density, and hydrography are investigated. Parametric range compensation functions, when applied with calibration data, will enable difference-frequency echoes to be expressed in physical units of volume backscattering, and backscattering spectra, including fish-swimbladder-resonances, to be analyzed.
On the Coriolis effect in acoustic waveguides
Authors: Wegert Henry , Reindl Leonard M. , Ruile Werner , Mayer Andreas P.
Published: May 2012

Rotation of an elastic medium gives rise to a shift of frequency of its acoustic modes, i.e., the time-period vibrations that exist in it. This frequency shift is investigated by applying perturbation theory in the regime of small ratios of the rotation velocity and the frequency of the acoustic mode. In an expansion of the relative frequency shift in powers of this ratio, upper bounds are derived for the first-order and the second-order terms. The derivation of the theoretical upper bounds of the first-order term is presented for linear vibration modes as well as for stable nonlinear vibrations with periodic time dependence that can be represented by a Fourier series.
Acoustic particle manipulation in a 40 kHz quarter-wavelength standing wave with an air boundary
Authors: Trippa Giuliana , Trine Stéphanie , Ventikos Yiannis , Coussios Constantin-C.
Published: May 2012

An implementation of a quarter-wavelength standing wave separator that exploits an air drum to achieve the pressure node is presented and characterized experimentally. The air drum configuration was implemented and tested in a set-up with a 40 kHz transducer immersed in a water tank with the quarter-wavelength gap being approximately 9 mm wide. Injection of suspensions of 5 μm and 45 μm diameter polystyrene particles at flow rates of 30 ml/h and 60 ml/h was studied and particle deflection towards the pressure node at the air drum surface was observed for a range of acoustic pressures. Computational results on single particle trajectories show good agreement with the experimental findings for the 45 μm particles, but not for the 5 μm particles. These were considered to behave as aggregates of higher effective dimension, due to their much higher number density relative to the 45 μm particles in the suspensions used. The set-up developed in this study includes a robust method for achieving a pressure node in a quarter-wavelength system and can represent the first step toward the development of an alternative separator configuration in respect to small channel MHz range operated systems for the manipulation of particles streams.
Sensitivity of the resonant ultrasound spectroscopy to weak gradients of elastic properties
Authors: Seiner Hanuš , Sedlák Petr , Bodnárová Lucie , Kruisová Alena , Landa Michal , de Pablos Angel , Belmonte Manuel
Published: May 2012

The applicability of resonant ultrasound spectroscopy on materials with weak spatial gradients in elastic coefficients and density is analyzed. It is shown that such gradients do not affect measurably the resonant spectrum but have a significant impact on the modal shapes. A numerical inverse procedure is proposed to explore the possibility of reconstructing the gradients from experimentally obtained modal shapes. This procedure is tested on synthetic data and applied to determine the gradient of the shear modulus in a continuously graded silicon nitride ceramic material. The results are in a good agreement with the gradient calculated for the examined material theoretically as well as with the results of other experimental methods.
Contributions of cochlea-scaled entropy and consonant-vowel boundaries to prediction of speech intelligibility in noise
Authors: Chen Fei , Loizou Philipos C.
Published: May 2012

Recent evidence suggests that spectral change, as measured by cochlea-scaled entropy (CSE), predicts speech intelligibility better than the information carried by vowels or consonants in sentences. Motivated by this finding, the present study investigates whether intelligibility indices implemented to include segments marked with significant spectral change better predict speech intelligibility in noise than measures that include all phonetic segments paying no attention to vowels/consonants or spectral change. The prediction of two intelligibility measures [normalized covariance measure (NCM), coherence-based speech intelligibility index (CSII)] is investigated using three sentence-segmentation methods: relative root-mean-square (RMS) levels, CSE, and traditional phonetic segmentation of obstruents and sonorants. While the CSE method makes no distinction between spectral changes occurring within vowels/consonants, the RMS-level segmentation method places more emphasis on the vowel-consonant boundaries wherein the spectral change is often most prominent, and perhaps most robust, in the presence of noise. Higher correlation with intelligibility scores was obtained when including sentence segments containing a large number of consonant-vowel boundaries than when including segments with highest entropy or segments based on obstruent/sonorant classification. These data suggest that in the context of intelligibility measures the type of spectral change captured by the measure is important.
Modeling auditory evoked brainstem responses to transient stimuli
Authors: Rønne Filip Munch , Dau Torsten , Harte James , Elberling Claus
Published: May 2012

A quantitative model is presented that describes the formation of auditory brainstem responses (ABRs) to tone pulses, clicks, and rising chirps as a function of stimulation level. The model computes the convolution of the instantaneous discharge rates using the “humanized” nonlinear auditory-nerve model of Zilany and Bruce [J. Acoust. Soc. Am. 122, 402–417 (2007)] and an empirically derived unitary response function which is assumed to reflect contributions from different cell populations within the auditory brainstem, recorded at a given pair of electrodes on the scalp. It is shown that the model accounts for the decrease of tone-pulse evoked wave-V latency with frequency but underestimates the level dependency of the tone-pulse as well as click-evoked latency values. Furthermore, the model correctly predicts the nonlinear wave-V amplitude behavior in response to the chirp stimulation both as a function of chirp sweeping rate and level. Overall, the results support the hypothesis that the pattern of ABR generation is strongly affected by the nonlinear and dispersive processes in the cochlea.
A hybrid finite element approach to modeling sound radiation from circular and rectangular ducts
Authors: Duan Wenbo , Kirby Ray
Published: May 2012

A numerical model based on a hybrid finite element method is developed that seeks to join sound pressure fields in interior and exterior regions. The hybrid method is applied to the analysis of sound radiation from open pipes, or ducts, and uses mode matching to couple a finite element discretization of the region surrounding the open end of the duct to wave based modal expansions for adjoining interior and exterior regions. The hybrid method facilitates the analysis of ducts of arbitrary but uniform cross section as well the study of conical flanges and here a modal expansion based on spherical harmonics is applied. Predictions are benchmarked against analytic solutions for the limiting cases of flanged and unflanged circular ducts and excellent agreement between the two methods is observed. Predictions are also presented for flanged and unflanged rectangular ducts, and because the hybrid method retains the sparse banded and symmetric matrices of the traditional finite element method, it is shown that predictions can be obtained within an acceptable time frame even for a three dimensional problem.
Identification of walked-upon materials in auditory, kinesthetic, haptic, and audio-haptic conditions
Authors: Giordano Bruno L. , Visell Yon , Yao Hsin-Yun , Hayward Vincent , Cooperstock Jeremy R. , McAdams Stephen
Published: May 2012

Locomotion generates multisensory information about walked-upon objects. How perceptual systems use such information to get to know the environment remains unexplored. The ability to identify solid (e.g., marble) and aggregate (e.g., gravel) walked-upon materials was investigated in auditory, haptic or audio-haptic conditions, and in a kinesthetic condition where tactile information was perturbed with a vibromechanical noise. Overall, identification performance was better than chance in all experimental conditions and for both solids and the better identified aggregates. Despite large mechanical differences between the response of solids and aggregates to locomotion, for both material categories discrimination was at its worst in the auditory and kinesthetic conditions and at its best in the haptic and audio-haptic conditions. An analysis of the dominance of sensory information in the audio-haptic context supported a focus on the most accurate modality, haptics, but only for the identification of solid materials. When identifying aggregates, response biases appeared to produce a focus on the least accurate modality—kinesthesia. When walking on loose materials such as gravel, individuals do not perceive surfaces by focusing on the most accurate modality, but by focusing on the modality that would most promptly signal postural instabilities.
Improving riverbed sediment classification using backscatter and depth residual features of multi-beam echo-sounder systems
Authors: Eleftherakis Dimitrios , Amiri-Simkooei AliReza , Snellen Mirjam , Simons Dick G.
Published: May 2012

Riverbed and seafloor sediment classification using acoustic remote sensing techniques is of high interest due to their high coverage capabilities at limited cost. This contribution presents the results of riverbed sediment classification using multi-beam echo-sounder data based on an empirical method. Two data sets are considered, both taken at the Waal River, namely Sint Andries and Nijmegen. This work is a follow-up to the work carried out by Amiri-Simkooei et al. [J. Acoust. Soc. Am. 126(4), 1724–1738 (2009)]. The empirical method bases the classification on features of the backscatter strength and depth residuals. A principal component analysis is used to identify the most appropriate and informative features. Clustering is then applied to the principal components resulting from this set of features to assign a sediment class to each measurement. The results show that the backscatter strength features discriminate between different classes based on the sediment properties, whereas the depth residual features discriminate classes based on riverbed forms such as the “fixed layer” (stone having riprap structure) and riverbed ripples. Combination of these two sets of features is highly recommended because they provide complementary information on both the composition and the structure of the riverbed.
Syllable structure and integration of voicing and manner of articulation information in labial consonant identification
Authors: Silbert Noah H.
Published: May 2012

Speech perception requires the integration of information from multiple phonetic and phonological dimensions. A sizable literature exists on the relationships between multiple phonetic dimensions and single phonological dimensions (e.g., spectral and temporal cues to stop consonant voicing). A much smaller body of work addresses relationships between phonological dimensions, and much of this has focused on sequences of phones. However, strong assumptions about the relevant set of acoustic cues and/or the (in)dependence between dimensions limit previous findings in important ways. Recent methodological developments in the general recognition theory framework enable tests of a number of these assumptions and provide a more complete model of distinct perceptual and decisional processes in speech sound identification. A hierarchical Bayesian Gaussian general recognition theory model was fit to data from two experiments investigating identification of English labial stop and fricative consonants in onset (syllable initial) and coda (syllable final) position. The results underscore the importance of distinguishing between conceptually distinct processing levels and indicate that, for individual subjects and at the group level, integration of phonological information is partially independent with respect to perception and that patterns of independence and interaction vary with syllable position.
Non-linear inverse scattering: High resolution quantitative breast tissue tomography
Authors: Wiskin J. , Borup D. T. , Johnson S. A. , Berggren M.
Published: May 2012

Recent published results in inverse scattering generally show the difficulty in dealing with moderate to high contrast inhomogeneities when employing linearized or iteratively linearized algorithms (e.g., distorted Born iterative method). This paper presents a fully nonlinear algorithm utilizing full wave field data, that results in ultrasound computed tomographic images from a laboratory breast scanner, and shows several such unique images from volunteer subjects. The forward problem, data collection process and inverse scattering algorithm used are discussed. A functional that represents the “best fit” between predicted and measured data is minimized, and therefore requires a very fast forward problem solver, Jacobian calculation, and gradient estimation, all of which are described. The data collection device is described. The algorithm and device yield quantitative estimates of human breast tissue in vivo. Several high resolution images, measuring ∼150 by 150 wavelengths, obtained from the 2D inverse scattering algorithms, using data collected from a first prototype, are shown and discussed. The quantitative values are compared with previous published work.
Further evidence that fundamental-frequency difference limens measure pitch discrimination
Authors: Micheyl Christophe , Ryan Claire M. , Oxenham Andrew J.
Published: May 2012

Difference limens for complex tones (DLCs) that differ in F0 are widely regarded as a measure of periodicity-pitch discrimination. However, because F0 changes are inevitably accompanied by changes in the frequencies of the harmonics, DLCs may actually reflect the discriminability of individual components. To test this hypothesis, DLCs were measured for complex tones, the component frequencies of which were shifted coherently upward or downward by ΔF = 0%, 25%, 37.5%, or 50% of the F0, yielding fully harmonic (ΔF = 0%), strongly inharmonic (ΔF = 25%, 37.5%), or odd-harmonic (ΔF = 50%) tones. If DLCs truly reflect periodicity-pitch discriminability, they should be larger (worse) for inharmonic tones than for harmonic and odd harmonic tones because inharmonic tones have a weaker pitch. Consistent with this prediction, the results of two experiments showed a non-monotonic dependence of DLCs on ΔF, with larger DLCs for ΔF’s of ±25% or ±37.5% than for ΔF’s of 0 or ±50% of F0. These findings are consistent with models of pitch perception that involve harmonic templates or with an autocorrelation-based model provided that more than just the highest peak in the summary autocorrelogram is taken into account.
Objective evaluation of speech signal quality by the prediction of multiple foreground diagnostic acceptability measure attributes
Authors: Sen Deep , Lu W.
Published: May 2012

A methodology is described to objectively diagnose the quality of speech signals by predicting the perceptual detectability of a selected set of distortions. The distortions are a statistically selected subset of the broad number of distortions used in diagnostic acceptability measure (DAM) testing. The justification for such a methodology is established from the analysis of a set of speech signals representing a broad set of distortions and their respective DAM scores. At the heart of the ability to isolate and diagnose the perceptibility of the individual distortions is a physiologically motivated cochlear model. The philosophy and methodology is thus distinct from traditional objective measures that are typically designed to predict mean opinion scores (MOS) using well versed functional psychoacoustic models. Even so, a weighted sum of these objectively predicted set of distortions is able to predict accurate and robust MOS scores, even when the reference speech signals have been subject to the Lombard effect.
Numerical analysis of eigenproblem for cavities by a particular integral method with a low frequency approximation of surface admittance
Authors: Leblanc Alexandre , Lavie Antoine
Published: May 2012

In this paper, a three-dimensional boundary element method for the eigenanalysis of complex-shaped cavity is presented. A particular integral method is proposed with general absorbing boundary conditions, well suited for determination of the lower modes. In this approach, a polynomial approximation of surface admittance is used with a recent class of compactly supported radial basis function. Two common absorbent models are employed in order to demonstrate the relevance of high-order approximation of the admittance. Resulting eigenproblems of several orders (linear to cubic) are thus performed on basic geometries and a car interior. Results show significant improvements for the computed damped eigenfrequencies and the associated modal reverberation time while using an approximation polynomial matching the surface admittance variation order.
Across-site patterns of modulation detection: Relation to speech recognition
Authors: Garadat Soha N. , Zwolan Teresa A. , Pfingst Bryan E.
Published: May 2012

The aim of this study was to identify across-site patterns of modulation detection thresholds (MDTs) in subjects with cochlear implants and to determine if removal of sites with the poorest MDTs from speech processor programs would result in improved speech recognition. Five hundred millisecond trains of symmetric-biphasic pulses were modulated sinusoidally at 10 Hz and presented at a rate of 900 pps using monopolar stimulation. Subjects were asked to discriminate a modulated pulse train from an unmodulated pulse train for all electrodes in quiet and in the presence of an interleaved unmodulated masker presented on the adjacent site. Across-site patterns of masked MDTs were then used to construct two 10-channel MAPs such that one MAP consisted of sites with the best masked MDTs and the other MAP consisted of sites with the worst masked MDTs. Subjects’ speech recognition skills were compared when they used these two different MAPs. Results showed that MDTs were variable across sites and were elevated in the presence of a masker by various amounts across sites. Better speech recognition was observed when the processor MAP consisted of sites with best masked MDTs, suggesting that temporal modulation sensitivity has important contributions to speech recognition with a cochlear implant.
A unified optical theorem for scalar and vectorial wave fields
Authors: Wapenaar Kees , Douma Huub
Published: May 2012

The generalized optical theorem is an integral relation for the angle-dependent scattering amplitude of an inhomogeneous scattering object embedded in a homogeneous background. It has been derived separately for several scalar and vectorial wave phenomena. Here a unified optical theorem is derived that encompasses the separate versions for scalar and vectorial waves. Moreover, this unified theorem also holds for scattering by anisotropic elastic and piezoelectric scatterers as well as bianisotropic (non-reciprocal) EM scatterers.
A directionally tunable but frequency-invariant beamformer on an acoustic velocity-sensor triad to enhance speech perception
Authors: Wu Yue Ivan , Wong Kainam Thomas , Yuan Xin , Lau Siu-kit , Tang Shiu-keung
Published: May 2012

Herein investigated are computationally simple microphone-array beamformers that are independent of the frequency-spectra of all signals, all interference, and all noises. These beamformers allow the listener to tune the desired azimuth-elevation “look direction.” No prior information is needed of the interference. These beamformers deploy a physically compact triad of three collocated but orthogonally oriented velocity sensors. These proposed schemes’ efficacy is verified by a jury test, using simulated data constructed with Mandarin Chinese (a.k.a. Putonghua) speech samples. For example, a desired speech signal, originally at a very adverse signal-to-interference-and-noise power ratio (SINR) of −30 dB, may be processed to become fully intelligible to the jury.
Acoustic particle velocity horns
Authors: Donskoy Dimitri M. , Cray Benjamin A.
Published: May 2012

The paper considers receiving acoustic horns designed for particle velocity amplification and suitable for use in vector sensing applications. Unlike conventional horns, designed for acoustic pressure amplification, acoustic velocity horns (AVHs) deliver significant velocity amplification even when the overall size of the horn is much less than an acoustic wavelength. An AVH requires an open-ended configuration, as compared to pressure horns which are terminated at the throat. The appropriate formulation, based on Webster’s one-dimensional horn equation, is derived and analyzed for single conical and exponential horns as well as for double-horn configurations. Predicted horn amplification factors (ratio of mouth-to-throat radii) were verified using numerical modeling. It is shown that three independent geometrical parameters principally control a horn’s performance: length l, throat radius R1, and flare rate. Below a predicted resonance region, velocity amplification is practically independent of frequency. Acoustic velocity horns are naturally directional, providing maximum velocity amplification along the boresight.
UVC Light Prophylaxis for Cutaneous Wound Infections in Mice
Authors: Dai Tianhong , Garcia Barbara , Murray Clinton K. , Vrahas Mark S. , Hamblin Michael R.
Published: May 2012

UVC light has long been known to be highly germicidal but has not been much developed as a therapy for infections. This study investigated the potential of UVC light for the prophylaxis of infections developing in highly contaminated superficial cutaneous wounds.
In vitro
studies demonstrated that the pathogenic bacteria
Pseudomonas aeruginosa
and
Staphylococcus aureus
were inactivated at UVC light exposures much lower than those needed for a similar effect on mammalian keratinocytes. Mouse models of partial-thickness skin abrasions infected with bioluminescent
P. aeruginosa
and
S. aureus
were developed. Approximately 10
7
bacterial cells were inoculated onto wounds measuring 1.2 by1.2 cm on the dorsal surfaces of mice. UVC light was delivered at 30 min after bacterial inoculation. It was found that for both bacterial infections, UVC light at a single radiant exposure of 2.59 J/cm
2
reduced the bacterial burden in the infected mouse wounds by approximately 10-fold in comparison to those in untreated mouse wounds (
P
< 0.00001). Furthermore, UVC light increased the survival rate of mice infected with
P. aeruginosa
by 58.3% (
P
= 0.0023) and increased the wound healing rate in mice infected with
S. aureus
by 31.2% (
P
< 0.00001). DNA lesions were observed in the UVC light-treated mouse wounds; however, the lesions were extensively repaired by 48 h after UVC light exposure. These results suggested that UVC light may be used for the prophylaxis of cutaneous wound infections.
Induction of Mycobacterial Resistance to Quinolone Class Antimicrobials
Authors: Malik Muhammad , Chavda Kalyan , Zhao Xilin , Shah Nirali , Hussain Syed , Kurepina Natalia , Kreiswirth Barry N. , Kerns Robert J. , Drlica Karl
Published: May 2012

An agar plate assay was developed for detecting the induction of drug-resistant mycobacterial mutants during exposure to inhibitors of DNA gyrase. When
Mycobacterium smegmatis
on drug-containing agar, resistant colonies arose over a period of 2 weeks. A
recA
deficiency reduced mutant recovery, consistent with involvement of the SOS response in mutant induction. The C-8-methoxy compounds gatifloxacin and moxifloxacin allowed the recovery of fewer resistant mutants than either ciprofloxacin or levofloxacin when present at the same multiple of the MIC; a quinolone-like 8-methoxy-quinazoline-2,4-dione was more effective at restricting the emergence of resistant mutants than its cognate fluoroquinolone. Thus, the structure of fluoroquinolone-like compounds affects mutant recovery. A spontaneous mutator mutant of
M. smegmatis
, obtained by growth in medium containing both isoniazid and rifampin, increased mutant induction during exposure to ciprofloxacin. Moreover, the mutator increased the size of spontaneous resistant mutant subpopulations, as detected by population analysis. Induction of ciprofloxacin resistance was also observed with
Mycobacterium tuberculosis
H37Rv. When measured with clinical isolates, no difference in mutant recovery was observed between multidrug-resistant (MDR) and pansusceptible isolates. This finding is consistent with at least some MDR isolates of
M. tuberculosis
lacking mutators detectable by the agar plate assay. Collectively, the data indicate that the use of fluoroquinolones against tuberculosis may induce resistance and that the choice of quinolone may be important for restricting the recovery of induced mutants.
Complete Genome Sequence of the Giant Pseudomonas Phage Lu11
Authors: Adriaenssens E. M. , Mattheus W. , Cornelissen A. , Shaburova O. , Krylov V. N. , Kropinski A. M. , Lavigne R.
Published: May 2012

The complete genome sequence of the giant
Pseudomonas
phage Lu11 was determined, comparing 454 and Sanger sequencing. The double-stranded DNA (dsDNA) genome is 280,538 bp long and encodes 391 open reading frames (ORFs) and no tRNAs. The closest relative is
Ralstonia
phage φRSL1, encoding 40 similar proteins. As such, Lu11 can be considered phylogenetically unique within the
Myoviridae
and indicates the diversity of the giant phages within this family.
Patient satisfaction with the colonoscopy procedure: endoscopists overestimate the importance of adverse physical symptoms: Table 1
Authors: Denters Maaike J , Deutekom Marije , Derkx Bert , Bossuyt Patrick M , Fockens Paul , Dekker Evelien
Published: May 2012

Background

Colonoscopy is a frequently performed procedure associated with a substantial burden for the patient. Most of what is known about patient satisfaction stems from surveys that target issues doctors believe to be important. It has been noticed that patients often focus on different aspects.

Aim

To have patients and endoscopists rate the extent to which each of a list of patient-generated issues-of-concern contributes to patient satisfaction with the colonoscopy procedure.

Subjects

A sample of consecutive patients undergoing colonoscopy in a Dutch tertiary teaching hospital and a convenience sample of endoscopists.

Methods

Colonoscopy patients and endoscopists were asked to rate on a five-point Likert scale the importance of 55 items concerning the colonoscopy procedure for patient satisfaction. Items were derived from focus group sessions with colonoscopy patients. Endoscopists were invited to rate the importance of the same set of items from a patient perspective. An analysis was carried out of whether patients and endoscopists rated the importance of items differently.

Results

69 patients and 34 endoscopists completed the questionnaire. The ratings of the endoscopists were significantly different from those of patients (p<0.0001). Endoscopists underestimated the importance of involving patients in decisions, discussing risks and complications, providing the opportunity for substantive questions and offering a comfortable temperature in the examination room. Endoscopists overestimated the importance of adverse physical symptoms, such as pain and abdominal cramps, and the role of the treating doctor.

Conclusions

Endoscopists do not have a good perception of the items that contribute most to patient satisfaction with the colonoscopy procedure. Overcoming this gap may be an essential step towards improving patient satisfaction by targeting those concerns most relevant to patients.
Planck-scale nonthermal correlations in a noncommutative geometry inspired Vaidya black hole
Authors: Mehdipour S. Hamid
Published: May 2012

Using the noncommutative geometry inspired Vaidya metric obtained in terms of coordinate coherent states and also utilizing the generalized uncertainty principle (GUP), we show that the nonthermal nature of the Hawking spectrum leads to Planck-scale nonthermal correlations between emitted modes of evaporation. Our analysis thus exhibits that owing to self-gravitational effects plus noncommutativity and GUP influences, information can emerge in the form of Planck-scale correlated emissions from the black hole.
Optical and electronic properties of RuO2 from first principles
Authors: Yang Z.J. , Li J. , Linghu R.F. , Cheng X.L. , Yang X.D.
Published: May 2012

The systematic trends of electronic structure and optical properties of RuO2 consisting of its four phases have been studied by using norm-conserving pseudopotential within the generalized gradient approximation for the exchange–correlation potential. The total density of states (DOS) and energy band structure investigations revealed that the fluorite phase possesses the broadest conduction bandwidth (0–30 eV) and the pyrite phase possesses the narrowest conduction bandwidth (0–5 eV). Study on partial DOS we found that O 2p electrons of the fluorite phase present a significant shift towards the Fermi level and Ru s and p electrons of the rutile phase contribute little to the orbital energy level formation. For the first time, we found that the norm-conserving pseudopotential failed to obtain the normal DOS and energy band distributions for a rutile Ru atom below about –40 eV, whereas such missing electronic distributions could be obtained successfully using an ultrasoft pseudo potential. Investigations on the optical properties further found that the rutile and CaCl2-type phases behave more similarly and the fluorite phase shows the most sensitive response in the whole radiation reaction region. The electron energy loss function revealed that the pyrite phase corresponds to the least relative intensity.
Classical and quantum wormholes in a 5D compact Kaluza–Klein theory
Authors: Darabi F.
Published: May 2012

We study the classical and quantum euclidean wormholes for an empty (4+1) dimensional Kaluza–Klein universe with a positive cosmological constant and a spatially flat Robertson–Walker type metric. It is shown that classical wormholes do not exist neither for the space–time sector nor the extra dimensional sector of this model, but two spectra of quantum wormholes as the solutions of the Wheeler–DeWitt equation exist that are consistent with the Hawking–Page conjecture about the necessary boundary conditions. In the spectrum where the external scale factor R shapes the quantum wormholes the internal scale factor a may play the role of effective matter source, and in the spectrum where the internal scale factor a shapes the quantum wormholes the external scale factor R may play the role of effective matter source.
Scattering and bound states of spin-0 particles in a nonminimal vector double-step potential
Authors: de Oliveira L.P. , de Castro A.S.
Published: May 2012

The problem of spin-0 particles subject to a nonminimal vector double-step potential is explored in the context of Duffin–Kemmer–Petiau theory. Surprisingly, one can never have an incident wave totally reflected, and the transmission amplitude has complex poles corresponding to bound states. The interesting special case of bosons embedded in a sign potential with its unique bound-state solution is analyzed as a limiting case.
Viscothermoelastic vibrations in micro-scale beam resonators with linearly varying thickness
Authors: Grover D.
Published: May 2012

In this paper the closed form expressions for the transverse vibrations of a homogenous, isotropic, thermally conducting, Kelvin–Voigt type viscothermoelastic thin beam with variable thickness, based on Euler–Bernoulli theory have been derived. The effects of relaxation times, thermomechanical coupling, surface conditions, and beam dimensions on energy dissipation induced by thermoelastic damping in microelectromechanical systems resonators are investigated for beams under clamped and simply supported conditions. Analytical expressions for deflection, temperature change, frequency shifts and thermoelastic damping in the beam have been derived. Some numerical results with the help of MATLAB programming software in the case of silicon nitride have also been presented. The computer simulated results with respect to the damping factor and frequency shift have been presented graphically.
Documentation quality and time costs
Authors: Brown Steven , Rosenbloom Trent S. , Hardenbrook Shawn P. , Clark Terry , Fielstein Elliot , Elkin Peter , Speroff Ted
Published: May 2012

The Department of Veterans Affairs (VA) performs over 800,000 disability exams and distributes over $37 billion in disability benefits per year. VA developed and deployed a computer-based disability exam documentation system in order to improve exam report quality and timeliness. We conducted a randomized controlled trial comparing joint disability examinations supported by computerized templates to the examinations documented via dictation, to determine if the system met the intended goals or had unintended consequences. Consenting veterans were randomized to undergo exams documented using computerized templates or via dictation. We compared exam report quality, documentation time costs, encounter length, total time to fulfill an exam request with a finalized exam report, and veteran satisfaction. Computer-based templates resulted in disability exam reports that had higher quality scores (p. 0.042) and were returned to the requesting office faster than exam reports created via dictation (p. 0.02).

Documentation time and veteran satisfaction were similar for both the documentation techniques. Encounter length was significantly longer for the template group. Computer-based templates impacted the VA disability evaluation system by improving report quality scores and production time and lengthening encounter times. Oversight bodies have called for mandated use of computer-based templates nationwide. We believe mandates regarding use of health information technology should be guided by data regarding its positive and negative impacts.
Parallel and Cache-Efficient In-Place Matrix Storage Format Conversion
Authors: Gustavson Fred , Karlsson Lars , Kågström Bo
Published: May 2012

Techniques and algorithms for efficient in-place conversion to and from standard and blocked matrix storage formats are described. Such functionality is required by numerical libraries that use different data layouts internally. Parallel algorithms and a software package for in-place matrix storage format conversion based on in-place matrix transposition are presented and evaluated. A new algorithm for in-place transposition which efficiently determines the structure of the transposition permutation a priori is one of the key ingredients. It enables effective load balancing in a parallel environment.
Estimating Derivatives of Noisy Simulations
Authors: Moré Jorge J. , Wild Stefan M.
Published: May 2012

We employ recent work on computational noise to obtain near-optimal difference estimates of the derivative of a noisy function. Our analysis relies on a stochastic model of the noise without assuming a specific form of distribution. We use this model to derive theoretical bounds for the errors in the difference estimates and obtain an easily computable difference parameter that is provably near-optimal. Numerical results closely resemble the theory and show that we obtain accurate derivative estimates even when the noisy function is deterministic.
Algorithm 918
Authors: Sadkane Miloud , Touhami Ahmed
Published: May 2012

Given a regular matrix pencil
λ
B
--
A
and a positively oriented contour
γ
in the complex plane, the spectral dichotomy methods applied to
λ
B
--
A
and
γ
consist in determining whether
λ
B
--
A
possesses eigenvalues on or in a neighborhood of
γ
. When no such eigenvalues exist, these methods compute iteratively the spectral projector
P
onto the right deflating subspace of
λ
B
--
A
associated with the eigenvalues inside/outside
γ
. The computation of the projector is accompanied by the spectral norm ||
H
|| of a Hermitian positive definite matrix
H
called the
dichotomy condition number
, which indicates the numerical quality of the spectral projector
P
. The smaller ||
H
|| is, the better this quality. This article presents a
MATLAB
program (specdicho) implementing the main types of spectral dichotomy where
γ
is a circle, an ellipse, the imaginary axis or a parabola.
Introduction to the special section on educational data mining
Authors: Calders Toon , Pechenizkiy Mykola
Published: May 2012

Educational Data Mining (EDM) is an emerging multidisciplinary research area, in which methods and techniques for exploring data originating from various educational information systems have been developed. EDM is both a learning science, as well as a rich application area for data mining, due to the growing availability of educational data. EDM contributes to the study of how students learn, and the settings in which they learn. It enables data-driven decision making for improving the current educational practice and learning material. We present a brief overview of EDM and introduce four selected EDM papers representing a crosscut of different application areas for data mining in education.
Data mining for improving textbooks
Authors: Agrawal Rakesh , Gollapudi Sreenivas , Kannan Anitha , Kenthapadi Krishnaram
Published: May 2012

We present our early explorations into developing a data mining based approach for enhancing the quality of textbooks. We describe a diagnostic tool to algorithmically identify deficient sections in textbooks. We also discuss techniques for algorithmically augmenting textbook sections with links to selective content mined from the Web. Our evaluation, employing widely-used textbooks from India, indicates that developing technological approaches to help improve textbooks holds promise.
Mapping question items to skills with non-negative matrix factorization
Authors: Desmarais Michel C.
Published: May 2012

Intelligent learning environments need to assess the student skills to tailor course material, provide helpful hints, and in general provide some kind of personalized interaction. To perform this assessment, question items, exercises, and tasks are presented to the student. This assessment relies on a mapping of tasks to skills. However, the process of deciding which skills are involved in a given task is tedious and challenging. Means to automate it are highly desirable, even if only partial automation that provides supportive tools can be achieved. A recent technique based on Non-negative Matrix Factorization (NMF) was shown to offer valuable results, especially due to the fact that the resulting factorization allows a straightforward interpretation in terms of a Q-matrix. We investigate the factors and assumptions under which NMF can effectively derive the underlying high level skills behind assessment results. We demonstrate the use of different techniques to analyze and interpret the output of NMF. We propose a simple model to generate simulated data and to provide lower and upper bounds for quantifying skill effect. Using the simulated data, we show that, under the assumption of independent skills, the NMF technique is highly effective in deriving the Q-matrix. However, the NMF performance degrades under different ratios of variance between subject performance, item difficulty, and skill mastery. The results corroborates conclusions from previous work in that high level skills, corresponding to general topics like World History and Biology, seem to have no substantial effect on test performance, whereas other topics like Mathematics and French do. The analysis and visualization techniques of the NMF output, along with the simulation approach presented in this paper, should be useful for future investigations using NMF for Q-matrix induction from data.
Survey on web spam detection
Authors: Spirin Nikita , Han Jiawei
Published: May 2012

Search engines became a de facto place to start information acquisition on the Web. Though due to web spam phenomenon, search results are not always as good as desired. Moreover, spam evolves that makes the problem of providing high quality search even more challenging. Over the last decade research on adversarial information retrieval has gained a lot of interest both from academia and industry. In this paper we present a systematic review of web spam detection techniques with the focus on algorithms and underlying principles. We categorize all existing algorithms into three categories based on the type of information they use: content-based methods, link-based methods, and methods based on non-traditional data such as user behaviour, clicks, HTTP sessions. In turn, we perform a subcategorization of link-based category into five groups based on ideas and principles used: labels propagation, link pruning and reweighting, labels refinement, graph regularization, and featurebased. We also define the concept of web spam numerically and provide a brief survey on various spam forms. Finally, we summarize the observations and underlying principles applied for web spam detection.
A study on the importance of and time spent on different modeling steps
Authors: Munson M. Arthur
Published: May 2012

Applying data mining and machine learning algorithms requires many steps to prepare data and to make use of modeling results. This study investigates two questions: (1) how time consuming are the pre- and post-processing steps? (2) how much research energy is spent on these steps? To answer these questions I surveyed practitioners about their experiences in applying modeling techniques and categorized data mining and machine learning research papers from 2009 according to the modeling step(s) they addressed. Survey results show that model building consumes only 14% of the time spent on a typical project; the remaining time is spent on pre- and post-processing steps. Both survey responses and the categorization of research papers show that data mining and machine learning researchers spend the majority of their energy on algorithms for constructing models and significantly less energy on other steps. These findings collectively suggest that there are research opportunities to simplify the steps that precede and follow model building.