bluuebunny/crossref_metadata_2025 huggingface dataset:
Vibrational circular-dichroism spectroscopy of homologous cyclic peptides designed to fold into β helices of opposite chirality
Authors: Kulp John L. , Owrutsky Jeffrey C. , Petrovykh Dmitri Y. , Fears Kenan P. , Lombardi Rosina , Nafie Laurence A. , Clark Thomas D.
Published: March 2011

Cyclic β-helical peptides have been developed as model structured biomolecules for examining peptide adsorption and conformation on surfaces. As a key prerequisite to circular-dichroism (CD) analysis of these model peptides on surfaces, their conformations and the corresponding vibrational spectra in the 1400-1800 cm−1 range were analyzed by vibrational circular-dichroism (VCD) spectroscopy in solution. The two model peptides (“β Leu and β Val”) were examined in chloroform, where they each fold into a homogeneous well-defined antiparallel double-stranded β-helical species, as determined previously by NMR and electronic CD spectroscopy. Because the β-helical conformations of β Leu and β Val are well characterized, the VCD spectra of these peptides can be unambiguously correlated with their structures. In addition, these two β-helical peptides differ from one another in two key respects that make them uniquely advantageous for CD analysis—first, while their backbone conformations are topologically similar, β Leu and β Val form helices of opposite chiralities; second, the two peptides differ in their sequences, i.e., composition of the side chains attached to the backbone. The observed VCD spectra for β Leu and β Val are roughly mirror images of each other, indicating that the VCD features are dominated by the chirality and conformation of the peptide backbone rather than by the peptide sequence. Accordingly, spectra similarly characteristic of peptide secondary structure can be expected for peptides designed to be structural analogs of β Leu and β Val while incorporating a variety of side chains for studies of surface adsorption from organic and aqueous solvents.
Micro- and Nanostructured Poly[oligo(ethylene glycol)methacrylate] Brushes Grown From Photopatterned Halogen Initiators by Atom Transfer Radical Polymerization
Authors: Ahmad Shah Alang , Leggett Graham J. , Hucknall Angus , Chilkoti Ashutosh
Published: March 2011

Photolithographic techniques have been used to fabricate polymer brush micro- and nanostructures. On exposure to UV light with a wavelength of 244 nm, halogens were selectively removed from films of chloromethylphenyltrichlorosilane and 3-(2-bromoisobutyramido)propyl-triethoxysilane on silicon dioxide. Patterning was achieved at the micrometer scale, by using a mask in conjunction with the incident laser beam, and at the nanometer scale, by utilizing interferometric lithography (IL). Friction force microscopy images of patterned surfaces exhibited frictional contrast due to removal of the halogen but no topographical contrast. In both cases the halogenated surface was used as an initiator for surface atom-transfer radical polymerization. Patterning of the surface by UV lithography enabled the definition of patterns of initiator from which micro- and nanostructured poly[oligo(ethylene glycol)methacrylate] bottle brushes were grown. Micropatterned brushes formed on both surfaces exhibited excellent resistance to protein adsorption, enabling the formation of protein patterns. Using IL, brush structures were formed that covered macroscopic areas (approximately 0.5 cm2) but exhibited a full width at half maximum height as small as 78 nm, with a period of 225 nm. Spatially selective photolytic removal of halogens that are immobilized on a surface thus appears to be a simple, rapid, and versatile method for the formation of micro- and nanostructured polymer brushes and for the control of protein adsorption.
Finite-element simulations of the effect of device design on channel temperature for AlGaN/GaN high electron mobility transistors
Authors: Douglas E. A. , Ren F. , Pearton S. J.
Published: March 2011

The effect of device design on maximum channel temperature for AlGaN/GaN high electron mobility transistors was investigated through finite element thermal simulations for dissipated power densities up to 5 W mm−1. The effects of substrate material, die size, and number of gate fingers were examined, as well as the divergence between maximum channel temperatures for two dimensional and three dimensional simulations. The maximum temperature increased as the die size decreased beyond a critical distance from the gates. The critical distance was dependent on the substrate material, with SiC requiring the smallest critical distance. At the maximum dissipated power, the temperature increased above ambient more than 300 °C for devices on sapphire substrates compared to an increase of 44 °C for devices on SiC substrates. As the number of gate fingers increased, the maximum channel temperature also increased, and a temperature gradient was observed along the gate width as well as between gate fingers.
Growth studies and optical properties of Zn1−xCdxO films grown by metal-organic chemical-vapor deposition
Authors: Sartel Corinne , Haneche Nadia , Vilar Christèle , Amiri Gaelle , Laroche Jean-Michel , Jomard François , Lusson Alain , Galtier Pierre , Sallet Vincent , Couteau Christophe , Lin Jenny , Aad Roy , Lérondel Gilles
Published: March 2011

Heteroepitaxial growths of Zn1−xCdxO films were performed on R-oriented sapphire substrates by metal-organic chemical-vapor deposition. The authors carried out secondary ion mass spectrometry analysis, scanning electron microscopy, photoluminescence, and ellipsometric measurements to investigate the incorporation of cadmium in the layers, as well as its influence on the optical properties. Compositions up to 5.5% Cd were obtained, tuning the photoluminescence emission from 3.36 (ZnO) to 3.1 eV and increasing the refractive index at 600 nm from 1.94 to 2.
Statistical model of clutter suppression in tissue harmonic imaging
Authors: Yan Xiang , Hamilton Mark F.
Published: March 2011

A statistical model is developed for the suppression of clutter in tissue harmonic imaging (THI). Tissue heterogeneity is modeled as a random phase screen that is characterized by its correlation length and variance. With the autocorrelation function taken to be Gaussian and for small variance, statistical solutions are derived for the mean intensities at the fundamental and second-harmonic frequencies in the field of a focused sound beam that propagates through the phase screen. The statistical solutions are verified by comparison with ensemble averaging of direct numerical simulations. The model demonstrates that THI reduces the aberration clutter appearing in the focal region regardless of the depth of the aberrating layer, with suppression of the clutter most effective when the layer is close to the source. The model is also applied to the reverberation clutter that is transmitted forward along the axis of the beam. As with aberration clutter, suppression of such reverberation clutter by THI is most pronounced when the tissue heterogeneity is located close to the source.
Normal waves in elastic bars of rectangular cross section
Authors: Krushynska Anastasiia A. , Meleshko Viatcheslav V.
Published: March 2011

This paper addresses a theoretical study of guided normal waves in elastic isotropic bars of rectangular cross-section by an analytical superposition method. Dispersion properties of propagating and evanescent modes for four families are analyzed in detail at various geometric and physical parameters of the bar. A comparison of the obtained results with the well-known properties for waves in infinite plates and circular cylinders is provided. The complicated structure of dispersion spectra is explained. High-frequency limiting values for phase and group velocities of normal waves are established for the first time. Calculated data agree well with the available experimental results.
Reducing visitor noise levels at Muir Woods National Monument using experimental management
Authors: Stack David W. , Peter Newman , Manning Robert E. , Fristrup Kurt M.
Published: March 2011

Noise impacts resources and visitor experience in many protected natural areas, and visitors can be the dominant source of noise. This experimental study tested the efficacy and acceptability of signs asking visitors to be quiet at Muir Woods National Monument, California. Signs declaring a “quiet zone” (at the park’s Cathedral Grove) or a “quiet day” (throughout the park) were posted on a randomized schedule that included control days (no signs). Visitor surveys were conducted to measure the cognitive and behavioral responses of visitors to the signs and test the acceptability of these management practices to visitors. Visitors were highly supportive of these management practices and reported that they consciously limited the amount of noise they produced. Sound level measurements showed substantial decreases on days when signs were posted.
Acoustic iridescence
Authors: Cox Trevor J.
Published: March 2011

An investigation has been undertaken into acoustic iridescence, exploring how a device can be constructed which alter sound waves, in a similar way to structures in nature that act on light to produce optical iridescence. The main construction had many thin perforated sheets spaced half a wavelength apart for a specified design frequency. The sheets create the necessary impedance discontinuities to create backscattered waves, which then interfere to create strongly reflected sound at certain frequencies. Predictions and measurements show a set of harmonics, evenly spaced in frequency, for which sound is reflected strongly. And the frequency of these harmonics increases as the angle of observation gets larger, mimicking the iridescence seen in natural optical systems. Similar to optical systems, the reflections become weaker for oblique angles of reflection. A second construction was briefly examined which exploited a metamaterial made from elements and inclusions which were much smaller than the wavelength. Boundary element method predictions confirmed the potential for creating acoustic iridescence from layers of such a material.
A coupled modal-finite element method for the wave propagation modeling in irregular open waveguides
Authors: Pelat Adrien , Felix Simon , Pagneux Vincent
Published: March 2011

In modeling the wave propagation within a street canyon, particular attention must be paid to the description of both the multiple reflections of the wave on the building facades and the radiation in the free space above the street. The street canyon being considered as an open waveguide with a discontinuously varying cross-section, a coupled modal-finite element formulation is proposed to solve the three-dimensional wave equation within. The originally open configuration—the street canyon open in the sky above—is artificially turned into a close waveguiding structure by using perfectly matched layers that truncate the infinite sky without introducing numerical reflection. Then the eigenmodes of the resulting waveguide are determined by a finite element method computation in the cross-section. The eigensolutions can finally be used in a multimodal formulation of the wave propagation along the canyon, given its geometry and the end conditions at its extremities: initial field condition at the entrance and radiation condition at the output.
Temporal suppression of the click-evoked otoacoustic emission level-curve
Authors: Verhulst Sarah , Harte James M. , Dau Torsten
Published: March 2011

The click-evoked otoacoustic emission (CEOAE) level-curve grows linearly for clicks below 40–60 dB and saturates for higher inputs. This study investigates dynamic (i.e., time-dependent) features of the CEOAE level-curve by presenting a suppressor-click less than 8 ms before the test-click. An alteration of the CEOAE level-curve, designated here as temporal suppression, was observed within this time period, and was shown to depend on the levels and the temporal separation of the two clicks. Temporal suppression occurred for all four subjects tested, and resulted in a vertical offset from the unsuppressed level-curve for test-click levels greater than 50 dB peak-equivalent level (peSPL). Temporal suppression was greatest for suppressors presented 1–4 ms before the test click, and the magnitude and time scale of the effect were subject dependent. Temporal suppression was furthermore observed for the short- (i.e., 6–18 ms) and long-latency (i.e., 24–36 ms) regions of the CEOAE, indicating that temporal suppression similarly affects synchronized spontaneous otoacoustic emissions (SSOAEs) and purely evoked CEOAE components. Overall, this study demonstrates that temporal suppression of the CEOAE level-curve reflects a dynamic process in human cochlear processing that works on a time scale of 0–10 ms.
Extension of deconvolution algorithms for the mapping of moving acoustic sources
Authors: Fleury Vincent , Bulté Jean
Published: March 2011

Several deconvolution algorithms are commonly used in aeroacoustics to estimate the power level radiated by static sources, for instance, the deconvolution approach for the mapping of acoustic sources (DAMAS), DAMAS2, CLEAN, and the CLEAN based on spatial source coherence algorithm (CLEAN-SC). However, few efficient methodologies are available for moving sources. In this paper, several deconvolution approaches are proposed to estimate the narrow-band spectra of low-Mach number uncorrelated sources. All of them are based on a beamformer output. Due to velocity, the beamformer output is inherently related to the source spectra over the whole frequency range, which makes the deconvolution very complex from a computational point of view. Using the conventional Doppler approximation and for limited time analysis, the problem can be separated into multiple independent problems, each involving a single source frequency, as for static sources. DAMAS, DAMAS2, CLEAN, and CLEAN-SC are then extended to moving sources. These extensions are validated from both synthesized data and real aircraft flyover noise measurements. Comparable performances to those of the corresponding static methodologies are recovered. All these approaches constitute complementary and efficient tools in order to quantify the noise level emitted from moving acoustic sources.
Virtual sensors for active noise control in acoustic–structural coupled enclosures using structural sensing: Robust virtual sensor design
Authors: Halim Dunant , Cheng Li , Su Zhongqing
Published: March 2011

The work was aimed to develop a robust virtual sensing design methodology for sensing and active control applications of vibro-acoustic systems. The proposed virtual sensor was designed to estimate a broadband acoustic interior sound pressure using structural sensors, with robustness against certain dynamic uncertainties occurring in an acoustic–structural coupled enclosure. A convex combination of Kalman sub-filters was used during the design, accommodating different sets of perturbed dynamic model of the vibro-acoustic enclosure. A minimax optimization problem was set up to determine an optimal convex combination of Kalman sub-filters, ensuring an optimal worst-case virtual sensing performance. The virtual sensing and active noise control performance was numerically investigated on a rectangular panel-cavity system. It was demonstrated that the proposed virtual sensor could accurately estimate the interior sound pressure, particularly the one dominated by cavity-controlled modes, by using a structural sensor. With such a virtual sensing technique, effective active noise control performance was also obtained even for the worst-case dynamics.
Sources of acoustic variation: Implications for production specificity and call categorization in chacma baboon (Papio ursinus) grunts
Authors: Meise Kristine , Keller Christina , Cowlishaw Guy , Fischer Julia
Published: March 2011

Elucidating the information content of vocal signals is fundamental to the understanding of animal communication. Acoustically distinct calls produced in specific contexts allow listeners to predict future events and choose adequate responses. However, the vocal repertoires of most terrestrial mammals consist of a limited number of call types that vary within and between categories. These “graded signaling systems” are thought to be rich in information, at the cost of increasing uncertainty regarding call categorization. In this study, patterns of acoustic variation in grunts of wild chacma baboons (Papio ursinus) were assessed in relation to different contexts, callers’ arousal, the presence of listeners, and individual identity. Although overall production specificity was low, and sensitive to the number of contexts under consideration, grunts given in three contexts could be statistically distinguished from each other. Contextual differences remained when controlling for caller arousal, suggesting that these differences cannot be explained by variation in arousal. No audience effect was detected, but individual identity was found to have an influence on acoustic structure. Overall, these results support the view that, in comparison to other signaling systems associated with hazardous conditions, lower production specificity might evolve under relaxed circumstances where unambiguous signaling is less important.
Blind single-channel suppression of late reverberation based on perceptual reverberation modeling
Authors: Tsilfidis Alexandros , Mourjopoulos John
Published: March 2011

A blind method for suppressing late reverberation from speech and audio signals is presented. The proposed technique operates both on the spectral and on the sub-band domains employing a single input channel. At first, a preliminary rough clean signal estimation is required and for this, any standard technique may be applied; however here the estimate is obtained through spectral subtraction. Then, an auditory masking model is employed in sub-bands to extract the reverberation masking index (RMI) which identifies signal regions with perceived alterations due to late reverberation. Utilizing a selective signal processing technique only these regions are suppressed through sub-band temporal envelope filtering based on analytical expressions. Objective and subjective measures indicate that the proposed method achieves significant late reverberation suppression for both speech and music signals over a wide range of reverberation time (RT) scenarios.
Vowel-related tongue movements in speech: Straight or curved paths? (L)
Authors: Löfqvist Anders
Published: March 2011

This paper examines tongue movements between the two vowels in sequences of vowel-labial consonant-vowel, addressing the question whether the movement is a straight line or a curved path. Native speakers of Japanese and Italian served as subjects. The linguistic material consisted of words where the bilabial consonant was either long or short. The inclusion of words with different consonant lengths was motivated by earlier findings that the tongue movement is often longer when the consonant is long, which may be due to a more curved movement path. Tongue movements were recorded using a three-transmitter magnetometer system. To assess the movement path, the movement magnitude was calculated in two ways, as a straight line, the Euclidean distance, and as the actual path, obtained by summing the individual Euclidean distances between successive samples from movement onset to offset. The ratio between the path and the Euclidean distance is 1 when the movement is a straight line and greater than 1 when the path is curved. Results show that in virtually all 21 cases examined the ratio was very close to 1 and in most cases 1.2 or less. There was no reliable influence of consonant length on the ratio.
Voice production model integrating boundary-layer analysis of glottal flow and source-filter coupling
Authors: Kaburagi Tokihiko
Published: March 2011

A voice production model is created in this work by considering essential aerodynamic and acoustic phenomena in human voice production. A precise flow analysis is performed based on a boundary-layer approximation and the viscous–inviscid interaction between the boundary layer and the core flow. This flow analysis can supply information on the separation point of the glottal flow and the thickness of the boundary layer, both of which strongly depend on the glottal configuration and yield an effective prediction of the flow behavior. When the flow analysis is combined with the modified two-mass model of the vocal fold [Pelorson et al. (1994). J. Acoust. Soc. Am. 96, 3416–3431], the resulting acoustic wave travels through the vocal tract and a pressure change develops in the vicinity of the glottis. This change can affect the glottal flow and the motion of the vocal folds, causing source-filter coupling. The property of the acoustic feedback is explicitly expressed in the frequency domain by using an acoustic tube model, allowing a clear interpretation of the coupling. Numerical experiments show that the vocal-tract input impedance and frequency responses representing the source-filter coupling have dominant peaks corresponding to the fourth and fifth formants. Results of time-domain simulations also suggest the importance of these high-frequency peaks in voice production.
Material property estimation for tubes and arteries using ultrasound radiation force and analysis of propagating modes
Authors: Bernal Miguel , Nenadic Ivan , Urban Matthew W. , Greenleaf James F.
Published: March 2011

Arterial elasticity has been proposed as an independent predictor of cardiovascular diseases and mortality. Identification of the different propagating modes in thin shells can be used to characterize the elastic properties. Ultrasound radiation force was used to generate local mechanical waves in the wall of a urethane tube or an excised pig carotid artery. The waves were tracked using pulse-echo ultrasound. A modal analysis using two-dimensional discrete fast Fourier transform was performed on the time–space signal. This allowed the visualization of different modes of propagation and characterization of dispersion curves for both structures. The urethane tube/artery was mounted in a metallic frame, embedded in tissue-mimicking gelatin, cannulated, and pressurized over a range of 10–100 mmHg. The k-space and the dispersion curves of the urethane tube showed one mode of propagation, with no effect of transmural pressure. Fitting of a Lamb wave model estimated Young’s modulus in the urethane tube around 560 kPa. Young’s modulus of the artery ranged from 72 to 134 kPa at 10 and 100 mmHg, respectively. The changes observed in the artery dispersion curves suggest that this methodology of exciting mechanical waves and characterizing the modes of propagation has potential for studying arterial elasticity.
Two-dimensional simulation of linear wave propagation in a suspension of polymeric microcapsules used as ultrasound contrast agents
Authors: Haïat Guillaume , Berti Romain , Galaz Belfor , Taulier Nicolas , Amman Jean-Jacques , Urbach Wladimir
Published: March 2011

A generation of tissue-specific stable ultrasound contrast agent (UCA) composed of a polymeric capsule with a perfluorocarbone liquid core has become available. Despite promising uses in clinical practice, the acoustical behavior of such UCA suspensions remains unclear. A simulation code (2-D finite-difference time domain, FDTD) already validated for homogeneous particles [Galaz Haiat, Berti, Taulier, Amman and Urbach, (2010). J. Acoust. Soc. Am. 127, 148–154] is used to model the ultrasound propagation in such UCA suspensions at 50 MHz to investigate the sensitivity of the ultrasonic parameters to physical parameters of UCA. The FDTD simulation code is validated by comparison with results obtained using a shell scatterer model. The attenuation coefficient (respectively, the sound velocity) increases (respectively, decreases) from 4.1 to 58.4 dB/cm (respectively, 1495 to 1428 m/s) when the concentration varies between 1.37 and 79.4 mg/ml, while the backscattered intensity increases non-linearly, showing that a concentration of around 30 mg/ml is sufficient to obtain optimal backscattering intensity. The acoustical parameters vary significantly as a function of the membrane thickness, longitudinal and transverse velocity, indicating that mode conversions in the membrane play an important role in the ultrasonic propagation. The results may be used to help manufacturers to conceive optimal liquid-filled UCA suspensions.
The effect of the coupling between the top plate and the fingerboard on the acoustic power radiated by a classical guitar (L)
Authors: García-Mayén Héctor , Santillán Arturo
Published: March 2011

An experimental investigation on the coupling between the fingerboard and the top plate of a classical guitar at low frequencies is presented. The study was carried out using a finished top plate under fixed boundary conditions and a commercial guitar. Radiated sound power was determined in one-third octave bands up to the band of 1 kHz based on measurements of sound intensity. The results provide evidence that the way in which the fingerboard and top plate are coupled is not a relevant factor in the radiated acoustic power of the classical guitar in the studied frequency range.
Cancellation of acoustic scattering from an elastic sphere
Authors: Guild Matthew D. , Alù Andrea , Haberman Michael R.
Published: March 2011

Recent research has suggested the possibility of creating acoustic cloaks using metamaterial layers to eliminate the acoustic field scattered from an elastic object. This paper explores the possibility of applying the scattering cancellation cloaking technique to acoustic waves and the use of this method to investigate its effectiveness in cloaking elastic and fluid spheres using only a single isotropic elastic layer. Parametric studies showing the influence of cloak stiffness and geometry on the frequency dependent scattering cross-section of spheres have been developed to explore the design space of the cloaking layer. This analysis shows that an appropriately designed single isotropic elastic cloaking layer can provide up to 30 dB of scattering reduction for ka values up to 1.6. This work also illustrates the importance of accounting for the elasticity of the object and the relevant limitations of simplistic quasi-static analyses proposed in recent papers.
A Radically Different Mechanism for
S
-Adenosylmethionine–Dependent Methyltransferases
Authors: Grove Tyler L. , Benner Jack S. , Radle Matthew I. , Ahlum Jessica H. , Landgraf Bradley J. , Krebs Carsten , Booker Squire J.
Published: March 2011

Methylation of the bacterial ribosome by two methyltransferases proceeds by an unusual radical mechanism.
The Hot Summer of 2010: Redrawing the Temperature Record Map of Europe
Authors: Barriopedro David , Fischer Erich M. , Luterbacher Jürg , Trigo Ricardo M. , García-Herrera Ricardo
Published: March 2011

Large parts of eastern Europe experienced exceptional warmth during the summer of 2010.
Enhancing Acupuncture by Low Dose Naltrexone
Authors: Hesselink Jan M Keppel , Kopsky David J
Published: March 2011

To find appropriate and effective treatment options for chronic pain syndromes is a challenging task. Multimodal treatment approach has been gaining acceptance for chronic pain. However, combining treatments, such as acupuncture, with rational pharmacology is still in its infancy. Acupuncture influences the opioid and cannabinoid system through releasing endogenous receptor ligands. Low dose naltrexone also acts on both these systems, and upregulates the opioid and cannabinoid receptors. The authors hypothesise that low dose naltrexone could enhance the pain-relieving effect of acupuncture.
Sliding Pressure Algometer, a Development in Eliciting Pressure Pain Thresholds at the Boundaries of Surface Markings of Abnormally Tender Regions
Authors: Macdonald Alexander John R
Published: March 2011

The pressure algometer probe tip is usually held stationary and pressure is steadily increased from zero until a pressure pain threshold (PPT) is elicited. In order to explore the extent of surface markings of abnormally tender regions in more detail an improved method is proposed whereby the pressure algometer is not kept still. It is slid over the tissues at a predetermined downward pressure and velocity to produce compressive, tensile and shear stress within underlying tissues. It is moved over surrounding non-tender regions until it reaches the surface overlying an abnormally tender region where a PPT is evoked. The probe is removed immediately and the skin marked. When this is repeated from different directions, the boundary of the surface markings of a tender region will appear in corresponding detail. Provided that this ‘sliding pressure algometer’ produces sufficiently similar amounts of stress when applied on separate occasions, it can be used to monitor the progress of a condition or the effects of treatment. To reduce cost and increase availability, this pressure algometer may be made of a plastic syringe converted into a gas-tight chamber.
Utility of screening for hepatocellular carcinoma among cirrhotics
Authors: Niravath Polly , Hayes Teresa , Hilsenbeck Susan
Published: March 2011

Background

Screening known cirrhotics for hepatocellular cancer (HCC) has long been a contentious topic. Studies to date have failed to conclusively prove or disprove the validity of α-fetoprotein (AFP) and hepatic ultrasound as screening mechanisms for HCC among cirrhotics, particularly in the American population. It is not clear whether these screening mechanisms provide any benefit in terms of reduced morbidity and mortality.

Methods

The study examined all patients with liver cirrhosis who developed HCC at the Michael E DeBakey VA Medical Center between 1999 and 2005. Those who were screened with AFP and/or imaging (either ultrasound, triphasic liver protocol CT or MRI) were compared with those patients who were not screened at all. The screened and unscreened patients were compared in terms of Barcelona Clinic Liver Cancer (BCLC) stage at the time of diagnosis.

Results

Statistical analysis revealed a significant difference between the screened and unscreened groups in terms of BCLC stage at diagnosis, with the unscreened group being diagnosed at later stages than the screened group. Of the 155 patients observed, 26 were appropriately screened, and 129 were not. The BCLC stages at diagnosis for the two groups were as follows: screened patients: 34.6%, 38.5%, 7.7% and 19.2% for BCLC stages A, B, C and D, respectively; unscreened patients: 12.4%, 24.8%, 27.1% and 35.7% for BCLC stages A, B, C and D, respectively. The different trend in the two groups was found to be statistically significant, with a p value of 0.004. Furthermore, among the screened group, no particular method of screening (AFP vs imaging vs combination) was shown to be superior to another.

Conclusions

Screening for HCC among cirrhotics using AFP and/or imaging every 6 months does correlate with HCC diagnosis at an earlier BCLC stage, thus portending better treatment options and improved prognosis. Therefore, screening all known cirrhotics for HCC may lead to decreased mortality.
The impact of epithelial biomarkers, local immune response and human papillomavirus genotype in the regression of cervical intraepithelial neoplasia grades 2–3
Authors: Øvestad Irene Tveiterås , Gudlaugsson Einar , Skaland Ivar , Malpica Anais , Munk Ane Cecilie , Janssen Emiel A M , Baak Jan P
Published: March 2011

Background and aims

15–30% of cases of cervical intraepithelial neoplasia grades 2–3 (CIN2–3) detected in punch biopsies regress spontaneously (ie, show CIN1 or less in the follow-up cone). Epithelial retinoblastoma protein (pRb), tumour suppressor protein (p53), HPV genotype and immunoreactive cells have been reported to be helpful in predicting regression but their interaction in regression prediction is unknown.

Material and methods

55 cases of CIN2–3 in cervical biopsies with subsequent cervical cones were studied retrospectively to assess how epithelial biomarkers, immunoreactive cells (with immunohistochemistry) and high-risk (hr) HPV genotypes (by the AMPLICOR and linear array tests) prognostically interact with epithelial pRb and p53.

Results

18% of CIN2–3s regressed (median biopsy–cone interval of 12.0 weeks, range 5.0–34.1 weeks). CIN2–3s that regressed had higher epithelial pRb and p53, lower stromal CD25+and CD138+, and higher CD8 cells than persistent lesions. They also had higher ratios of CD4+/CD25+and CD8+/CD25 in stroma and epithelium. HPV16 correlated with low pRb and low CD8+. With multivariate analysis a combined high ratio of CD8+/CD25+in the stroma, high epithelial pRb and p53 expression had independent value to predict the regression.

Conclusions

CIN2–3 lesions with a non-hrHPV16 infection, high ratios of stromal CD8+/CD25+and high epithelial expression of pRb or p53 are associated with spontaneous regression.
Peritoneal mesothelial hyperplasia associated with gynaecological disease: a potential diagnostic pitfall that is commonly associated with endometriosis
Authors: Oparka Richard , McCluggage W Glenn , Herrington C Simon
Published: March 2011

Aims

To describe the clinicopathological features of florid peritoneal mesothelial hyperplasia associated with gynaecological disease.

Methods

Review of a series of 44 cases where there was significant peritoneal mesothelial proliferation, usually on the surface of the ovary, which resulted in diagnostic problems, often including a consideration of malignancy.

Results

Florid mesothelial proliferation was associated with a variety of benign and malignant lesions, most commonly endometriosis. The most characteristic morphological appearance was that of small bland tubules and nests and cords of cells often embedded in fibrous tissue, sometimes with a linear arrangement. In a minority of cases, there were closely packed small glands and papillae resulting in mimicry of a serous proliferation; psammoma bodies were present in one such case. In several cases, the groups of mesothelial cells either exhibited true lymphovascular invasion or were surrounded by spaces closely simulating lymphovascular invasion. Although most cases were appreciated to represent a reactive mesothelial proliferation, several were referred with a presumed or possible diagnosis of mesothelioma, low-grade serous carcinoma, adenocarcinoma, adenomatoid tumour or Sertoli cell tumour. Positive staining with calretinin and negative staining with Ber-EP4 often helped to identify the cells as mesothelial rather than epithelial.

Conclusions

Florid peritoneal mesothelial hyperplasia can occur in association with a variety of gynaecological disorders. Recognition of this phenomenon and appreciation that it can produce worrisome histological patterns, particularly when associated with endometriosis, is key to reaching the correct diagnosis.
Art in wartime:The First Wounded, London Hospital, August 1914
Authors: Park M P , Park R H R
Published: March 2011

John Lavery'sThe First Wounded, London Hospital, August 1914records a memorable event in the First World War. This painting and the archives of the Royal London Hospital provide a fascinating insight into the nursing and medical care of these early war casualties.
Late Holocene glacial activity in Manatee Valley, southern Coast Mountains, British Columbia, Canada
Authors: Koehler Lindsey , Smith Dan J.
Published: March 2011

The dendroglaciologic and lichenometric research methodologies employed in this study provide a perspective of glaciological conditions from 5 ka to present in a remote headwater area of the British Columbia Coast Mountains. Since Holocene ice fronts of four glaciers at this site periodically extended below treeline, previous glacier advances overrode and buried forests beneath till deposits. This study suggests that glaciers were expanding into standing forests at 4.76 and 3.78 ka. Following glacier expansion at 3.78 ka, a period of recession ensued when glaciers withdrew upvalley long enough for the development of deep pedogenic surfaces and the growth of trees exceeding 300 years. Investigations at Beluga and Manatee glaciers benchmark a subsequent episode of significant glacial expansion at 2.42 ka referred to as the “Manatee Advance”. This advance has regional correlatives and is distinguished from the Tiedemann Advance at Manatee Glacier by documentation of substantive ice front retreat between the two episodes. Examination of Little Ice Age (LIA) deposits in the study area allowed for presentation and application of a revised Rhizocarpon spp. lichen growth curve. Lichenometric surveys of lateral moraines associated with Beluga, Manatee, and Oluk glaciers provided limited insight into their early LIA behaviour but record advances during the 15th and 16th centuries. Locally, glaciers achieved their maximum LIA size prior to an early to mid 18th century moraine-building event. This reconstruction of Holocene glacial history offers insights consistent with the emerging record of glacier activity described for other southern British Columbia Coast Mountain glaciers.
Tholeiitic to calc-alkaline cyclic volcanism in the Roy Group, Chibougamau area, Abitibi Greenstone Belt — revised stratigraphy and implications for VHMS explorationGeological Survey of Canada Contribution 20100254. Ministère des Ressources naturelles et de la Faune Contribution 8439-2010-2011-17.
Authors: Leclerc François , Bédard Jean H. , Harris Lyal B. , McNicoll Vicki J. , Goulet Normand , Roy Patrice , Houle Patrick
Published: March 2011

The Roy Group in the Chibougamau area of the Abitibi subprovince, Southeastern Superior craton, Quebec, exemplifies Archean volcanic evolution. The Roy Group formed in two volcanic cycles, with voluminous basal mafic tholeiitic volcanic rocks being capped by a thin succession of calc-alkaline felsic volcanic rocks, banded iron formations, and cherts that represent regional stratigraphic markers. The Gilman Formation is thought to represent the mafic base of the 2nd Roy Group volcanic cycle. Our new mapping reveals that the Gilman Formation (North of the Lac Doré Layered intrusive complex) can be subdivided into a tholeiitic lower part (David member), a calc-alkaline extrusive sequence (Allard member), and a tholeiitic, more mafic upper part (Bruneau Formation, newly defined here). New U–Pb zircon ages on Allard member tuffs (2726.6 ± 0.7 Ma) are within error of those obtained from rhyolites of the Waconichi Formation (2728.2–2728.7 Ma), which underlies the Gilman Formation. These ages, along with geochemical and lithological similarities, imply that the Allard member belongs to the Waconichi Formation and that the David member occupies the same stratigraphic position as the Obatogamau Formation. The upper part of the former Gilman Formation is reassigned to the new Bruneau Formation. A thin transitional calc-alkaline basalt unit at the base of the Allard member is geochemically similar to basalts occurring at the top of the Lemoine member of the Waconichi Formation near the Lemoine mine, suggesting that the Allard member is slightly younger than the Lemoine member, and that its base (also associated with iron formation, breccia, and chert) represents a regional stratigraphic break favourable for volcanogenic-hosted massive sulphide (VHMS) exploration.
Revision of the tephrostratigraphy of the lower Sixtymile River area, Yukon Territory, Canada
Authors: Westgate J. A. , Preece S. J. , Jackson L. E.
Published: March 2011

Five distinctive tephra beds are preserved in fine-grained sediments on a prominent terrace strath along the lower Sixtymile River of the Yukon Territory. Commencing with the oldest unit, they are TA, SM3, Gold Run, Hollis 2, and Flat Creek tephra beds. The uppermost three tephra beds have rhyolitic compositions, the other two are bimodal with a much more basic glass phase. Three glass fission-track age determinations point to deposition during the early-Middle Pleistocene. We correct an error in an earlier study by clarifying that Flat Creek tephra is younger than Gold Run tephra, TA tephra is older.
Recovery of a telomere-truncated chromosome via a compensating translocation in maize
Authors: Gaeta Robert T. , Danilova Tatiana V. , Zhao Changzeng , Masonbrink Rick E. , McCaw Morgan E. , Birchler James A.
Published: March 2011

Maize-engineered minichromosomes are easily recovered from telomere-truncated B chromosomes but are rarely recovered from A chromosomes. B chromosomes lack known genes, and their truncation products are tolerated and transmitted during meiosis. In contrast, deficiency gametes resulting from truncated A chromosomes prevent their transmission. We report here a de novo compensating translocation that permitted recovery of a large truncation of chromosome 1 in maize. The truncation (trunc-1) and translocation with chromosome 6 (super-6) occurred during telomere-mediated truncation experiments and were characterized using single-gene fluorescent in situ hybridization (FISH) probes. The truncation contained a transgene signal near the end of the broken chromosome and transmitted together with the compensating translocation as a heterozygote to approximately 41%–55% of progeny. Transmission as an addition chromosome occurred in ~15% of progeny. Neither chromosome transmitted through pollen. Transgene expression (Bar) cosegregated with trunc-1 transcriptionally and phenotypically. Meiosis in T1 plants revealed eight bivalents and one tetravalent chain composed of chromosome 1, trunc-1, chromosome 6, and super-6 in diplotene and diakinesis. Our data suggest that de novo compensating translocations allow recovery of truncated A chromosomes by compensating deficiency in female gametes and by affecting chromosome pairing and segregation. The truncated chromosome can be maintained as an extra chromosome or together with the super-6 as a heterozygote.
Genes encoding the biotin carboxylase subunit of acetyl-CoA carboxylase from Brassica napus and parental species: cloning, expression patterns, and evolution
Authors: Li Zhi-Guo , Yin Wei-Bo , Song Li-Ying , Chen Yu-Hong , Guan Rong-Zhan , Wang Jing-Qiao , Wang Richard R.-C. , Hu Zan-Min
Published: March 2011

Comparative genomics is a useful tool to investigate gene and genome evolution. Biotin carboxylase (BC), an important subunit of heteromeric acetyl-CoA carboxylase (ACCase) that is a rate-limiting enzyme in fatty acid biosynthesis in dicots, catalyzes ATP, biotin carboxyl carrier protein, and CO2to form carboxybiotin carboxyl carrier protein. In this study, we cloned four genes encoding BC from Brassica napus L. (namely BnaC.BC.a, BnaC.BC.b, BnaA.BC.a, and BnaA.BC.b), and two were cloned from each of the two parental species Brassica rapa L. (BraA.BC.a and BraA.BC.b) and Brassica oleracea L. (BolC.BC.a and BolC.BC.b). Sequence analyses revealed that in B. napus the genes BnaC.BC.a and BnaC.BC.b were from the C genome of B. oleracea, whereas BnaA.BC.a and BnaA.BC.b were from the A genome of B. rapa. Comparative and cluster analysis indicated that these genes were divided into two major groups, BnaC.BC.a, BnaA.BC.a, BraA.BC.a, and BolC.BC.a in group-1 and BnaC.BC.b, BnaA.BC.b, BraA.BC.b, and BolC.BC.b in group-2. The divergence of group-1 and group-2 genes occurred in their common ancestor 13–17 million years ago (MYA), soon after the divergence of Arabidopsis and Brassica (15–20 MYA). This time of divergence is identical to the previously reported triplicated time of paralogous subgenomes of diploid Brassica species and the divergence date of group-1 and group-2 genes of α-carboxyltransferase, another subunit of heteromeric ACCase, in Brassica. Reverse transcription PCR revealed that the expression level of group-1 and group-2 genes varied in different organs, and the expression patterns of the two groups of genes were similar in different organs, except in flower. However, two paralogs of group-2 BC genes from B. napus could express differently in mature plants tested by generating BnaA.BC.b and BnaC.BC.b promoter–β-glucuronidase (GUS) fusions. The amino acid sequences of proteins encoded by these genes were highly conserved, except the sequence encoding predicted plastid transit peptides. The plastid transit peptides on the BC precursors of Brassica (71–72 amino acid residues) were predicted based on AtBC protein, compared, and confirmed by fusion with green fluorescent protein. Our results will be helpful in elucidating the evolution and the regulation of ACCase in the genus Brassica.
A hydromechanical relation governing internal stability of cohesionless soil
Authors: Moffat Ricardo , Fannin R. Jonathan
Published: March 2011

Results are presented from permeameter tests involving unidirectional seepage flow through reconstituted specimens of four widely graded cohesionless soils. The onset of instability is defined by a significant decrease in local hydraulic gradient over a relatively short period of time. The novel concept of a hydromechanical path in stress ([Formula: see text]) – gradient (ijk) space is proposed, which describes the response to seepage flow during testing and terminates at the value of critical hydraulic gradient. The path terminus establishes a hydromechanical boundary governing the onset of seepage-induced internal instability in one-dimensional flow. The boundary represents a failure envelope, which is different for each of the four soils tested. A ranking of seepage-induced instability for each soil, from most unstable to least unstable, is found similar, but not identical to, the susceptibility to internal instability determined from empirical analysis of the gradation shape.
Spatial and temporal progression of internal erosion in cohesionless soil
Authors: Moffat Ricardo , Fannin R. Jonathan , Garner Stephen J.
Published: March 2011

Permeameter tests were performed on four widely graded cohesionless soils, to study their susceptibility to internal erosion. Test specimens were reconstituted as a saturated slurry, consolidated, and then subjected to multi-stage seepage flow under increasing hydraulic gradient. The occurrence of internal instability is described qualitatively, from visual observations through the wall of the permeameter during a test and from post-test observations; it is also described quantitatively, from change of hydraulic gradient within the specimen and from axial displacement during a test. The results provide a novel insight into the spatial and temporal progression of seepage-induced internal instability. This insight yields an improved characterization of suffusion and suffosion in cohesionless soils, the progression of which appears governed by a critical combination of hydraulic gradient and effective stress.
Undrained shear strength properties of organic harbor mud at low consolidation stress levels
Authors: Schlue Benjamin Friedrich , Mörz Tobias , Kreiter Stefan
Published: March 2011

Dredging operations in European harbors for maintenance of navigable water depth produce vast amounts of harbor mud. Between 2005 and 2007, the second largest harbor construction project in Germany was designed as a pilot study, using dredged harbor mud as backfill material to avoid expensive deposition or ex situ treatment. During this project, strong surface deformations of the backfill highlighted the need for an improved assessment of undrained shear strength of naturally liquid harbor mud. The strength of harbor mud cannot be measured accurately under corresponding low in situ effective stress levels by standard laboratory tests. Therefore, a large-scale oedometer cell with a diameter of 22 cm was designed, providing the opportunity to perform vane shear measurements during consolidation. This study shows that East Harbor mud is a very sensitive, organogenic clay of extremely high plasticity, exhibiting very small undrained shear strength when compared with other cohesive soils. Both the peak and residual undrained shear strengths are shown to increase about 3%–4% per log-cycle increase in secondary compression time (days).