bluuebunny/crossref_metadata_2025 huggingface dataset:
Resin composites in dentistry: the monomer systems
Authors: Peutzfeldt Anne
Published: October 2007

The present review outlines the history of monomers, used in resin composites, motivates further development, and highlights recent and ongoing research reported in the field of dental monomer systems. The monomer systems of most present‐day resin composites are based on BisGMA, developed some 40 years ago, or derivatives of BisGMA. In the remaining resin composites, urethane monomers or oligorners are used as the basis of the monomer system. The main deficiencies of current resin composites are polymerization shrinkage and insufficient wear resistance under high masticatory forces. Both factors are highly influenced by the mooonier system, and considerable efforts are being made around the world to reduce or eliminate these undesirable properties. The use of fluoride‐releasing monomer systems, some of which are under investigation, has been suggested to mitigate the negative effects of marginal gaps formed in consequence of polymerization shrinkage. The very crux of the problem has also been approached with the synthesis of potentially low‐shrinking/non‐shrinking resin composites involving ring opening or cyclopolymerizable monomers. By the use of additives with a supposed chain transfer agent function, monomer systems have been formulated that improve the degree of conversion of methacrylate double bonds and mechanical properties. Many promising monomer systems have been devised, the implementation of which may be expected to improve the longevity of resin composite fillings and expand the indications for resin composites.
Intraepithelial lymphocytes bearing the γ/δ receptor in the oral and jejunal mucosa in patients with dermatitis herpetiformis
Authors: Patinen Pertti , Savilahti Erkki , Hietanen Jarkko , Malmström Maria , Mäki Markku , Reunala Timo
Published: October 2007

Lymphocytes bearing T cell receptor (TcR) γ/δ are increased in the jejunal mucosa of patients with dermatitis herpetiformis (DH) and coeliac disease. In this study, we examined whether increased numbers of γ/δ TcR positive lymphocytes occur in the oral mucosa of patients with DH. Oral and jejunal rnucosal biopsies were taken from 13 newly diagnosed and 13 gluten free diet (GFD)‐treated patients with DH. Monoclonal antibodies and avidin‐biotin peroxidase method was used for staining, and TcR positive cells were counted from the buccal and jejunal epithelium. Very few γ/δ TcR positive lymphocytes were seen in the buccal epithelium of untreated or GFD‐treated DH patients (median 0.4 and 0.3 cells/mm2), whereas α/β TcR positive lymphocytes were frequent in both groups of DH patients (154 and 250 cells/mm2) and healthy controls (135 cells/mm2). The numbers of γ/δ TcR positive intraepithelial lymphocytes were significantly increased in the jejunum of both untreated (43 cells/mm) and GFD‐treated (27 cells/mm) DH patients compared to control patients (2.2 cells/mm). The present study did not, therefore, disclose any evidence for active recruitment of γ/δ TcR positive lymphocytes in the oral epithelium, but showed substantial amounts of intraepithelial γ/β TcR positive lymphocytes both in DH patients and healthy controls.
Quantification of human myeloperoxidase in oral fluids
Authors: Ortiz Griselle C. , Rahemtulla Britta , Tsurudome Steven A. , Chaves Eros , Rahemtulla Firoz
Published: October 2007

Peroxidase activity in human whole saliva is derived from salivary peroxidase and myeloperoxidase. Present spectrophotometric assays are relatively nonspecific and influenced by ions present in salivary secretions, resulting in an over and/or underestimation of peroxidase activities. Specific polydonal or monoclonal antibodies would greatly simplify the identification of salivary peroxidase and myeloperoxidase in human saliva and determine the relative contribution of each enzyme to the total peroxidase activity in human saliva. In the present study, a highly purified preparation of myeloperoxidase was used to raise polydonal antibodies against the antigen. The antibodies were purified and extensively characterized in terms of their ability to interact with the antigen, with other mammalian peroxidases, and with other proteins present in salivary fluids. The antibodies recognized only myeloperoxidase and did not cross‐react with any of the substances tested, showing that these antibodies can be used to detect and differentiate myeloperoxidase from other peroxidases in saliva. We have also developed and tested a sandwich ELISA which can be used in a clinical setting to quantify myeloperoxidase in whole saliva and gingival crevicular fluid.
Oral, perioral and systemic pathosis in HgCl2–induced autoimmunity in the BN rat
Authors: Warfvinge Gunnar , Peszkowski Michael J. , Hultman Per , Larsson Åke
Published: October 2007

Male BN rats were repeatedly skin‐injected with HgCl2 solution and sacrificed after 6, 9, 14, 21, 28 or 42 days, Mononuclear cell infiltrates were observed in the oral mucosa and in lacrimal, salivary and thyroid glands from 6–9 days onwards, with a peak at 14–21 days. Imrminohistochemistry identified these cells as predominantly T cells with some NK cells but very few B cells. Reversible parenchymal changes were observed but there was no obvious persistent tissue destruction. Serum tilers of IgE, IgG1, anti–laminin and anti–DNP. but not IgG2a antibodies, were raised and peaked at 14–21 days. However, there was no correlation, within animals, between these tilers and the extent of mononudear cell infiltration. Mercury was histochemically detected within dendritic cells/macrophages in the connective tissue stroma of the glands and in the oral mucosa, but no correlation was found between the distribution of mercury and the degree of inflammation. We conclude that the accumulation of mononuclear cells in oral and perioral tissues of HgCl2–treated BN rats does not represent a local immune response to tissue–retained Hg. Instead, we propose that the extravasation represents an epiphenomenon that is not necessarily deleterious to the infiltrated organ.
Indicators of salivary gland inflammation in primary Sjögren's syndrome
Authors: Cuida Mihaela , Halse Anne‐Kristine , Johannessen Anne Christine , Tynning Turid , Jonsson Roland
Published: October 2007

The aim of this study was to establish additional indicators in saliva and plasma which are associated with salivary gland inflammation in patients with primary Sjögren's syndrome (SS). ELISA assays were used to determine the concentrations of sICAM‐1, sVCAM‐1, sIL‐2Rz, IgA, IgG, calprotectin and albumin in parotid saliva, whole saliva and plasma samples. Soluble ICAM‐1 was present in whole and parotid saliva samples from primary SS patients. Soluble VCAM‐1 and sIL‐IRx could not be detected in salivary samples from either primary SS or control subjects. IgA, IgG, calprotectin and albumin concentrations were higher in both whole and parotid saliva in the patient group compared with the control group. The results showed increased levels of calprotectin in all saliva samples compared to plasma, suggesting that calprotectin may be locally produced. Increased plasma values of sICAM‐1. sVCAM‐1, SIL‐2Rα, IgA, IgG and calprotectin were detected in primary SS patients when compared to controls. The output/min of IgA. IgG, calprotectin and albumin was decreased in SS patients. Plasma levels of various proteins could offer information concerning glandular and extraglandular inflammatory processes. However, salivary levels of these proteins (particularly sICAM‐1) tend to reflect more the local inflammatory activity, providing a convenient and non‐invasive tool for diagnosis.
Potential side effects of dental amalgam restorations
Authors: Bratel John , Haraldson Torgny , Ottosson Jan‐Otto
Published: October 2007

A group of 50 consecutive patients, referred for self‐reported complaints which they related to dental amalgam restorations, was compared with control patients matched by age, sex and postal zip code. All patients were subjected to a psychiatric examination and a set of rating scales and questionnaires, and the symptoms were related to the mercury levels in blood, urine and hair. A psychiatric diagnosis was established in 70% of the patients in the index group versus 14% in the control group. The prevailing symptoms were anxiety, asthenia and depression. Mercury levels in blood, urine and hair were similar among index cases and controls, and were far below critical levels of mercury intoxication. There was no correlation between mercury levels and the severity of the reported symptoms. Therefore, mercury was not a likely cause of the complaints. Instead, the reported symptoms were part of a broad spectrum of mental disorders.
Erosive tooth wear: prevalence and severity in Swedish winetasters
Authors: Wiktorsson Ann‐Marie , Zimmerman Mikael , Angmar‐Månsson Birgit
Published: October 2007

Full‐time Swedish winetasters test on average 20–50 different wines, nearly 5 days a week. As the pH of wines ranges from 3.0 to 3.6, there is a potential risk for tooth erosion. The aims of this study were to document the prevalence and seventy of tooth erosion in qualified winetasters in relation to number of years of winetasting. salivary flow rate, and buffer capacity. The subjects comprised all 19 qualified winetasters (7 women and 12 men. aged 29–64 years employed in Stockholm by Vin & Sprit AB. the state‐owned company‐marketing nines and spirits. At intraoral examination, tooth surface loss was registered and documented by photography. Salivary flow rate and buffer capacity of unstimulated and stimulated saliva were measured. Data on occupational background and dental and medical histories were collected. Fourteen subjects had tooth erosion, the severity varying from mild to extreme, mainly on the labiocervical surfaces of maxillary incisors and canines. The severity of the erosion tended to increase with years of occupational exposure. Caries activity in all subjects was low. 14 subjects had low unstimulated salivary flow rates. It was concluded that full‐time winetasting is an occupation associated with increased risk for tooth erosion.
Electrical impedance. A method to evaluate subtle changes of the human oral mucosa
Authors: Nicander Ingrid , Rozell Barbro Lundh , Rundquist Lars , Ollmar Stig
Published: October 2007

In a previous study, we mapped the differences in electrical impedance between various anatomical locations in the oral mucosa. We now explore the ability of the impedance technique to detect mild reactions in the buccal mucosa induced by the irritant sodium lauryl sulphate. This substance was applied for 15 min at a concentration of 2%to the mucosa of 26 healthy subjects. A contralateral site was used as a control. Responses were evaluated by measuring electrical impedance before exposure and after removal of the irritant, and also by visual inspection and histology. Magnitude and phase of impedance were determined in the frequency range 1 kHz to 1 MHz at 5 depth settings, and 4 physically distinct indices were calculated from the impedance data. The results showed the response to be at its maximum 5 min after removal of the test chamber, for all indices. These changes were statistically significant, whereas visual and histological alterations were slight or negligible. We conclude that the electrical impedance technique is capable of detecting mucosal changes in the invisible or barely visible range, and that the mucosal response to sodium lauryl sulphate is well characterised by the 4 indices.
Oral mucosal side effects of cytotoxic chemotherapy of testicular cancer. A retrospective study
Authors: Herlofson Bente Brokstad , Norman‐Pedersen Kjell , Redfors Maria , Fossa Sophie Dorothea
Published: October 2007

Cancer chemotherapy often leads to injury of normal cells. Adverse effects on oral mucosa have been documented for several cytotoxic treatment regimens. The aim of the present retrospective study was to evaluate incidence and degree of oral soft tissue side‐effects of a cisplatin‐based chemotherapy regimen used for treating testicular cancer. The study was based upon a questionnnaire mailed to 56 consecutive patients treated at the Norwegian Radium Hospital. A total of 39 individuals joined the study, as 2 patients refused and 15 did not reply. The patients were divided into two groups, a case group (24 individuals) having received 4‐7 cycles of cisplatin‐based chemotherapy in addition to surgery, and a control group (15: individuals) treated with surgery alone. The study revealed that 62% of the patients in the chemotherapy group developed adverse soft tissue reactions, with mucositis and pain as chief complaints, whereas none in the control group experienced any mucosal complications.
Measurement of lip and skin pigmentation using reflectance spectrophotometry
Authors: Thibodeau Edward A. , D'Ambrosio Joseph A.
Published: October 2007

Previous methods for evaluating the color of oral epithelial tissues have relied primarily on subjective indices and interpretation. In this study, a narrow‐band reflectance spectrophotometer was used to measure melanin and hemoglobin pigmentation in the lips and skin of individuals who self‐reported their skin type from a choice of white, olive, or black. Significant differences in melanin pigmentation were observed among skin types and at most anatomical sites evaluated between skin types. Hemoglobin levels were not significantly different among skin types at most anatomical sites, but differences were observed among anatomical sites within each skin color group. Within each skin type, melanin (except in blacks) and hemoglobin were significantly higher for both the upper and lower lips compared with most other anatomical sites. Results suggest that reflectance spectophotometry is a useful tool for quantifying differences in melanin and hemoglobin pigmentation in oral tissues.
AAA+ ATPases: Achieving Diversity of Function with Conserved Machinery
Authors: White Susan Roehl , Lauring Brett
Published: September 2007

AAA+ adenosine triphosphatases (ATPases) are molecular machines that perform a wide variety of cellular functions. For instance, they can act in vesicle transport, organelle assembly, membrane dynamics and protein unfolding. In most cases, the ATPase domains of these proteins assemble into active ring‐shaped hexamers. As AAA+ proteins have a common structure, a central issue is determining how they use conserved mechanistic principles to accomplish specific biological actions. Here, we review the features and motifs that partially define AAA+ domains, describe the cellular activities mediated by selected AAA+ proteins and discuss the recent work, suggesting that various AAA+ machines with very different activities employ a common core mechanism. The importance of this mechanism to human health is demonstrated by the number of genetic diseases caused by mutant AAA+ proteins.
Recombinant bovine zona pellucida glycoproteins ZP3 and ZP4 coexpressed in Sf9 cells form a sperm‐binding active hetero‐complex
Authors: Kanai Saeko , Yonezawa Naoto , Ishii Yuichiro , Tanokura Masaru , Nakano Minoru
Published: September 2007

The zona pellucida (ZP) is a transparent envelope that surrounds the mammalian oocyte and mediates species‐selective sperm–egg interactions. Porcine and bovine ZPs are composed of the glycoproteins ZP2, ZP3, and ZP4. We previously established an expression system for porcine ZP glycoproteins (ZPGs) using baculovirus in insect Sf9 cells. Here we established a similar method for expression of bovine ZPGs. The recombinant ZPGs were secreted into the medium and purified by metal‐chelating column chromatography. A mixture of bovine recombinant ZP3 (rZP3) and rZP4 coexpressed in Sf9 cells exhibited inhibitory activity for bovine sperm–ZP binding similar to that of a native bovine ZPG mixture, whereas neither bovine rZP3 nor rZP4 inhibited binding. An immunoprecipitation assay revealed that the coexpressed rZP3/rZP4 formed a hetero‐complex. We examined the functional domain structure of bovine rZP4 by constructing ZP4 mutants lacking the N‐terminal domain or lacking both the N‐terminal and trefoil domains. When either of these mutant proteins was coexpressed with bovine rZP3, the resulting mixtures exhibited inhibitory activity comparable to that of the bovine rZP3/rZP4 complex. Hetero‐complexes of bovine rZP3 and porcine rZP4, or porcine rZP3 and bovine rZP4, also inhibited bovine sperm–ZP binding. Our results demonstrate that the N‐terminal and trefoil domains of bovine rZP4 are dispensable for formation of the sperm‐binding active bovine rZP3/rZP4 complex and, furthermore, that the molecular interactions between rZP3 and rZP4 are conserved in the bovine and porcine systems.
Rayleigh scattering of acoustic waves in rigid porous media
Authors: Boutin Claude
Published: September 2007

This paper describes the long wave scattering effect in gas saturated porous media using the homogenization method. To investigate the deviation from the continuum description, the multiscale asymptotic expansions are developed up to the third order. The leading (zeroth) order leads to the Biot-Allard continuum description. The correction of first order induces nonlocal terms in the dynamic Darcy law and thermal behavior, without modifying the wave characteristics. The correction of second order introduces additional dispersion effects on the velocity and attenuation. This theoretical approach is illustrated by analytical results in the simple case of a periodic array of slits.
Guided wave modes in porous cylinders: Theory
Authors: Wisse C. J. , Smeulders D. M. J. , Chao G. , van Dongen M. E. H.
Published: September 2007

The classical theory of wave propagation in elastic cylinders is extended to poro-elastic mandrel modes. The classical theory predicts the existence of undamped L modes and damped C, I, and Z modes. These waves also appear in poro-elastic mandrels, but all of them become damped because of viscous effects. The presence of the Biot slow bulk wave in the poro-elastic material is responsible for the generation of additional mandrel modes. One of them was already discussed by Feng and Johnson, and the others can be grouped together as so-called D modes. The damping of these D modes is at least as high as the damping of the free-field slow wave.
Non-ossicular signal transmission in human middle ears: Experimental assessment of the “acoustic route” with perforated tympanic membranes
Authors: Voss Susan E. , Rosowski John J. , Merchant Saumil N. , Peake William T.
Published: September 2007

Direct acoustic stimulation of the cochlea by the sound-pressure difference between the oval and round windows (called the “acoustic route”) has been thought to contribute to hearing in some pathological conditions, along with the normally dominant “ossicular route.” To determine the efficacy of this acoustic route and its constituent mechanisms in human ears, sound pressures were measured at three locations in cadaveric temporal bones [with intact and perforated tympanic membranes (TMs)]: (1) in the external ear canal lateral to the TM, PTM; (2) in the tympanic cavity lateral to the oval window, POW; and (3) near the round window, PRW. Sound transmission via the acoustic route is described by two concatenated processes: (1) coupling of sound pressure from ear canal to middle-ear cavity, HPCAV≡PCAV∕PTM, where PCAV represents the middle-ear cavity pressure, and (2) sound-pressure difference between the windows, HWPD≡(POW−PRW)∕PCAV. Results show that: HPCAV depends on perforation size but not perforation location; HWPD depends on neither perforation size nor location. The results (1) provide a description of the window pressures based on measurements, (2) refute the common otological view that TM perforation location affects the “relative phase of the pressures at the oval and round windows,” and (3) show with an intact ossicular chain that acoustic-route transmission is substantially below ossicular-route transmission except for low frequencies with large perforations. Thus, hearing loss from TM perforations results primarily from reduction in sound coupling via the ossicular route. Some features of the frequency dependence of HPCAV and HWPD can be interpreted in terms of a structure-based lumped-element acoustic model of the perforation and middle-ear cavities.
Validity of the limp model for porous materials: A criterion based on the Biot theory
Authors: Doutres Olivier , Dauchez Nicolas , Génevaux Jean-Michel , Dazel Olivier
Published: September 2007

The validity of using the limp model for porous materials is addressed in this paper. The limp model is derived from the poroelastic Biot model assuming that the frame has no bulk stiffness. Being an equivalent fluid model accounting for the motion of the frame, it has fewer limitations than the usual equivalent fluid model assuming a rigid frame. A criterion is proposed to identify the porous materials for which the limp model can be used. It relies on a new parameter, the frame stiffness influence (FSI), based on porous material properties. The critical values of FSI under which the limp model can be used are determined using a one-dimensional analytical modeling for two boundary sets: absorption of a porous layer backed by a rigid wall and radiation of a vibrating plate covered by a porous layer. Compared with other criteria, the criterion associated with FSI provides information in a wider frequency range and can be used for configurations that include vibrating plates.
Feature weighting in “chick-a-dee” call notes ofPoecile atricapillus
Authors: Nickerson Carly M. , Bloomfield Laurie L. , Dawson Michael R. W. , Charrier Isabelle , Sturdy Christopher B.
Published: September 2007

Artificial neural networks were trained to discriminate between different note types from the black-capped chickadee (Poecile atricapillus) “chick-a-dee” call. Each individual note was represented as a vector of summary features taken from note spectrograms and networks were trained to respond to exemplar notes of one type and to fail to respond to exemplar notes of another type. Following initial network training, the network was presented novel notes in which individual acoustic features had been modified. The strength of the response of the network to each novel and shifted note was recorded. When network responses were plotted as a function of the degree of acoustic feature modification and training context, it became clear that modifications of some acoustic features had significant effects on network responses, while others did not. Moreover, the training context of the network also played a role in the responses of networks to manipulated test notes. The implications of using artificial neural networks to generate testable hypotheses for animal research and the role of context are discussed.
Optimal poroelastic layer sequencing for sound transmission loss maximization by topology optimization method
Authors: Lee Joong Seok , Kim Eun Il , Kim Yoon Young , Kim Jung Soo , Kang Yeon June
Published: September 2007

Optimal layer sequencing of a multilayered acoustical foam is solved to maximize its sound transmission loss. A foam consisting of air and poroelastic layers can be optimized when a limited amount of a poroelastic material is allowed. By formulating the sound transmission loss maximization problem as a one-dimensional topology optimization problem, optimal layer sequencing and thickness were systematically found for several single and ranges of frequencies. For optimization, the transmission losses of air and poroelastic layers were calculated by the transfer matrix derived from Biot’s theory. By interpolating five intrinsic parameters among several poroelastic material parameters, distinct air-poroelastic layer distributions were obtained; no filtering or postprocessing was necessary. The optimized foam layouts by the proposed method were shown to differ depending on the frequency bands of interest.
Developing standards for distortion product otoacoustic emission measurements
Authors: Mills David M. , Feeney M. Patrick , Drake Eli J. , Folsom Richard C. , Sheppard Lianne , Seixas Noah S.
Published: September 2007

Characteristics of distortion product otoacoustic emission (DPOAE) measurements were investigated by comparing responses from two different emission measurement systems in 40 volunteers (78 ears) and making test–retest measurements of each system in 20 ears. For transformation of results between systems, it was shown that the minimum data set consisted of input–output (growth) functions obtained by stepping stimulus levels across a wide range, for each set of stimulus frequencies (1–8kHz). Linear transformations were considered which involved either recalibration of the emission amplitude (vertical transformation) or of the stimulus levels (horizontal transformation). Horizontal transformations provided better agreement between growth functions from the two systems. For frequencies 4–8kHz, the means of the horizontal shifts required ranged from 8 to 14dB, clearly exceeding test–retest variability. The optimal horizontal transformation was derived and applied uniformly to all emission measurements; correlations r=0.81–0.89 were found between transformed emission amplitudes. To minimize the necessity for such transformations and to reduce the variability found both within and between systems, development of standardized equipment and methods is suggested for DPOAE measurements, including: (1) an optimized in-ear probe assembly; (2) use of intensity calibration; and (3) a focus on emission “threshold” measurement and analysis.
Differential reductions in acoustic startle document the discrimination of speech sounds in rats
Authors: Floody Owen R. , Kilgard Michael P.
Published: September 2007

The intensity of a noise-induced startle response can be reduced by the presentation of an otherwise neutral stimulus immediately before the noise (“prepulse inhibition” or PPI). This effect has been used to study the detection of gaps and other stimuli, but has been applied infrequently to complex stimuli or the ability to discriminate among multiple stimuli. To address both issues and explore the potential of PPI, rats were presented a series of 5 tasks, most contrasting a pair of speech sounds. One of these (the “standard” stimulus) occurred frequently but rarely preceded the startle stimulus. The second occurred infrequently (as an “oddball”) and always preceded a noise. In each such task, startle responses were inhibited more by the oddball than by the standard stimulus, usually within the first test. This suggests that PPI can be adapted to studies of the discrimination of speech and other complex sounds, and that this method can provide useful information on subjects' ability to discriminate with greater ease and speed than other methods.
Nonperiodicity of the flow within the gap of a thermoacoustic couple at high amplitudes
Authors: Berson Arganthaël , Blanc-Benon Philippe
Published: September 2007

The flow inside a thermoacoustic couple is investigated experimentally using particle image velocimetry. Measurements show the oscillation of the shear layers flowing out of a single stack, thus forming an asymmetric vortex street at high driving amplitudes. Development of vortices is also observed within the gap of a thermoacoustic couple. It causes the flow not to repeat from one acoustic period to another. The nonperiodicity of the flow will lead to unsteady heat transfer between the stack and heat exchangers and to the oscillation of the cooling load.
Reconstructing the adhesion stiffness distribution in a laminated elastic plate: Exact and approximate inverse scattering solutions
Authors: Leiderman Ricardo , Barbone Paul E. , Braga Arthur M. B.
Published: September 2007

This paper formulates and solves a time harmonic inverse scattering problem to reconstruct the effective stiffness distribution of an adhesive bond in a layered elastic plate. The motivation is based on the assumption that localized adhesion flaws that diminish bond stiffness also tend to diminish bond strength. The formulation is based on the invariant imbedding method, applies to isotropic and anisotropic elastic layers, and is essentially that of identifying embedded acoustic sources in elastic layered structures. This paper presents two solutions for the inverse problem: the Born approximation and the exact solution. The example calculations compare the two solutions and show that when imperfections are too large in either magnitude or extent the accuracy of the Born approximation breaks down. The impact of noise and uncertainties in the background properties in the inversion is also investigated. A regularization strategy is introduced in the exact solution that controls solution sensitivity in regions with low signal to noise ratio.
On pressure-frequency relations in the excised larynx
Authors: Alipour Fariborz , Scherer Ronald C.
Published: September 2007

The purpose of this study was to find relationships between subglottal pressure (Ps) and fundamental frequency (F0) of phonation in excised larynx models. This included also the relation between F0 and its rate of change with pressure (dF∕dP). Canine larynges were prepared and mounted over a tapered tube that supplied pressurized, heated, and humidified air. Glottal adduction was accomplished either by using two-pronged probes to press the arytenoids together or by passing a suture to simulate lateral cricoarytenoid muscle activation. The pressure-frequency relation was obtained through a series of pressure-flow sweep experiments that were conducted for eight excised canine larynges. It was found that, at set adduction and elongation levels, the pressure-frequency relation is nonlinear, and is highly influenced by the adduction and elongation. The results indicated that for the lower phonation mode, the average rate of change of frequency with pressure was 2.9±0.7Hz∕cm H2O, and for the higher mode was 5.3±0.5Hz∕cm H2O for adduction changes and 8.2±4.4Hz∕cm H2O for elongation changes. The results suggest that during speech and singing, the dF∕dP relationships are taken into account.
Loss-improved electroacoustical modeling of small Helmholtz resonators
Authors: Starecki Tomasz
Published: September 2007

Modeling of small Helmholtz resonators based on electroacoustical analogies often results in significant disagreement with measurements, as existing models do not take into account some losses that are observed in practical implementations of such acoustical circuits, e.g., in photoacoustic Helmholtz cells. The paper presents a method which introduces loss corrections to the transmission line model, resulting in substantial improvement of simulations. Values of the loss corrections obtained from comparison of frequency responses of practically implemented resonators with computer simulations are presented in tabular and graphical form. A simple analytical function that can be used for interpolation or extrapolation of the loss corrections for other dimensions of the Helmholtz resonators is also given. Verification of such a modeling method against an open two-cavity Helmholtz structure shows very good agreement between measurements and simulations.
An experimental study of the acoustic impedance characteristics of human hair
Authors: Treeby Bradley E. , Pan Jie , Paurobally Roshun M.
Published: September 2007

Previous analytical and empirical studies of the human auditory system have shown that the cues used for localization are modified by the inclusion of nonrigid scattering surfaces (clothing, hair etc). This paper presents an investigation into the acoustic impedance properties of human hair. The legitimacy of a locally reactive surface assumption is investigated, and an appropriate boundary condition is formulated to account for the physiological composition of a human head with hair. This utilizes an equivalent impedance parameter to allow the scattering boundary to be defined at a reference plane coincident with the inner rigid surface of the head. Experimental examination of a representative synthetic hair material at oblique incidence is used to show that a locally reactive surface assumption is legitimate. Additional experimental analysis of a simple scattering problem illustrates that the equivalent impedance must be used in favor of the traditional surface impedance to yield physically correct pressure magnitudes. The equivalent acoustic impedance properties of a representative range of human hair samples are discussed, including trends with sample thickness, fiber diameter, bulk density, and mass.
Point of impact prediction in isotropic and anisotropic plates from the acoustic emission data
Authors: Kundu Tribikram , Das Samik , Jata Kumar V.
Published: September 2007

It is shown in this paper that the conventional triangulation technique is not very reliable for locating the impact point even in isotropic plates when the sensors are placed close to the point of strike for two reasons: First, it is difficult to pinpoint the exact time of arrival of the signal and, second, the Lamb modes in a plate are dispersive. Dispersive signals attenuate differently at various frequencies and propagate with different speeds causing distortions in the received signals, and thus introduce error in the time of flight measurement. The triangulation technique assumes that wave speeds in all directions are the same, which is not true for anisotropic plates. Here an alternative approach based on an optimization scheme is proposed to locate the point of impact in isotropic and anisotropic plates. A formulation is presented for the general anisotropic case. Experiments are carried out with an aluminum plate by dropping balls on the plate and picking up acoustic signals at different locations. The impact points predicted by the conventional triangulation technique and the proposed modified method are compared for this isotropic plate. Then it is investigated how the prediction would change if the plate is assumed to have some anisotropy.
Copolymerization of 2-[3-(2H-Benzotriazol-2-yl)-4-hydroxyphenyl]ethyl Methacrylate with Styrene
Authors: Schovanec Martin , Horálek Jiří , Podzimek Štěpán , Šňupárek Jaromír
Published: September 2007

Radical copolymerization of 2-[3-(2H-benzotriazol-2-yl)-4-hydroxyphenyl]ethyl methacrylate (M1) with styrene (M2) at 70 °C in 1,4-dioxane was investigated and the reactivity ratios were determined. The copolymerization was carried out as batch copolymerization to a low conversion or as copolymerization with a continuous addition of monomers at higher instantaneous conversion. The monomer reactivity ratios of the copolymerizable UV stabilizer 2-[3-(2H-benzotriazol-2-yl)-4-hydroxyphenyl]ethyl methacrylate with styrene were determined using the Finemann-Ross plot for both copolymeration techniques. The estimated reactivity ratios were r1 = 0.588 and r2 = 0.6 for the technique of continuous addition of monomers and r1 = 0.462 and r2 = 0.476 and for the batch experiment. The copolymerization exhibited an azeotrope at f1 = 0.507, thus a copolymer with microstructure close to the alternating one was formed at this ratio of comonomers.
Determination of High-Molecular-Weight n-Alkanes of Petroleum Origin by High-Temperature Gas Chromatography
Authors: Šimáček Pavel , Maxa Daniel , Šebor Gustav
Published: September 2007

This paper deals with the identification and determination of high-molecular-weight n-alkanes of petroleum origin using high-temperature gas chromatography (HTGC). Analysed samples, which were the concentrates of saturated hydrocarbons, differed in both the total content of n-alkanes and their distribution. They were analysed on various types of HTGC columns differing in length and inner diameter. While the determined total content of n-alkanes was comparable for all the chromatographic columns, differences were found in the efficiency of separation of n-alkanes over C40 as well as in their quantitative elution.
A survey of epicuticular waxes among genera of Triticeae. I. Ultrastructure of glumes and some leaves as observed with the scanning electron microscope
Authors: Baum Bernard R. , Tulloch A. P. , Bailey L. Grant
Published: October 2007

This is the first part of an electron microscopic and chemical study on epicuticular wax. Epicuticular wax ultrastructural morphology (EWUM) of glumes of representatives of 21 genera of Triticeae was determined with the aid of a scanning electron microsope (SEM). Leaves of several genera were examined for specific comparisons to be done later when chemical results are available. This study is based on 120 out of 251 seed accessions obtained from various sources from natural habitats, all grown for the purpose of both SEM and chemical studies in a plot in Ottawa, Canada. Vouchers are preserved and have been critically identified. The results of EWUM demonstrate that the various genera can be characterized by patterns of relative frequencies of the basic wax crystal categories: plates (P), knobs (K), and filaments (F). The variation within each category is also described. Frequencies of P, K, and F have been summarized for each genus. The frequency data have been analysed by principal-coordinate analyses and by Jardine–Sibson Bk cluster analysis to assess and interpret the phenetic relationships between the generic EWUM frequency patterns.
Revisions in the technique of epi-illumination light microscopy for the study of floral and vegetative apices
Authors: Posluszny U. , Scott M. G. , Sattler R.
Published: October 2007

Many improvements have been made in the technique of epi-illumination light microscopy. These modifications have resulted in micrographs of better resolution and subsequently in greater flexibility in the study of floral and vegetative apices. The preparation, mounting, microscopy, and photography of apices are discussed in detail. The correlation of this technique with others such as scanning electron microscopy and serial sectioning is discussed. The numerous applications of epi-illumination light microscopy are considered.
The marine algae of British Columbia and northern Washington: division Rhodophyta (red algae), class Rhodophyceae, order Rhodymeniales
Authors: Hawkes Michael W. , Scagel Robert F.
Published: October 2007

This is a floristic treatment of benthic marine red algae (Rhodophyta) in the order Rhodymeniales which occur in British Columbia and northern Washington. The following 12 species in 9 genera are recorded and illustrated: Botryocladia pseudodichotoma (Farlow) Kylin, Fauchea fryeana Setchell, Fauchea laciniata J. G. Agardh, Faucheocolax attenuata Setchell, Fryeella gardneri (Setchell) Kylin, Gastroclonium subarticulatum (Turner) Kützing, Lomentaria hakodatensis Yendo, Minium parvum Moe, Rhodymenia californica Kylin, Rhodymenia pacifica Kylin, Rhodymenia pertusa (Postels et Ruprecht) J. Agardh, and Rhodymeniocolax botryoidea Setchell. Rhodymenia stipitata Kylin is treated as a taxonomic synonym of Rhodymenia pertusa. Previous reports of Coeloseira parva Hollenberg from British Columbia and Leptofauchea auricularis Dawson and Leptofauchea pacifica Dawson from northern Washington were based on misidentifications or could not be confirmed. Also provided is a historical background of the Rhodymeniales. Keys to and descriptions of local taxa (at the ordinal, familial, and generic levels), as well as information on synonyms, location of type specimens, type localities, and what is known about the life histories, distribution, seasonality, and habitats of all local taxa, are provided. Rhodymenialean species occurring in British Columbia and northern Washington which are also reported in the California flora are listed, as are those which are restricted to one or the other flora. References are given and representative specimens cited that document our concepts of the taxa and their morphological variability, seasonality, and geographical distributions.
Allelopathic effects of Cladonia cristatella on ectomycorrhizal fungi common to bituminous strip-mine spoils
Authors: Goldner W. R. , Hoffman F. M. , Medve R. J.
Published: October 2007

Acetone–toluene extracts of Cladonia cristatella inhibited the growth of fungi known to form ectomycorrhizal associations with trees commonly found on bituminous strip-mine spoils in western Pennsylvania. Growth of Pisolithus tinctorius and Suillus luteus was completely inhibited by C. cristatella extracts over a 30-d bioassay period. Thelephora terrestris was dead after 17 d. The growth of Cenococcum graniforme was unaffected by lichen extracts. D-Usnic acid, a major secondary compound of the C. cristatella extract, was found to inhibit the growth of P. tinctorius. This inhibition, however, did not account for the total inhibition of P. tinctorius demonstrated by the gross acetone–toluene extract. Other secondary compounds, and potential allelopathic substances, present in the extract were barbatic acid, didymic acid, condidymic acid, subdidymic acid, fumarprotocetraric acid, squamatic acid, and rhodocladonic acid.
Effect of mannitol on the in vitro growth, temperature optimum, and subsequent ectomycorrhizal infectivity of Pisolithus tinctorius
Authors: Pons Susana , Mudge Kenneth W. , Negm Fayek B.
Published: October 2007

The effect of mannitol on in vitro growth, temperature optimum, and subsequent ectomycorrhizal infectivity of Pisolithus tinctorius isolate T1069 was investigated. In vitro growth on mannitol as a sole carbon source was 50–140% of that on equimolar glucose. The pH optimum for growth on mannitol was 6.0 with a minor peak at 4.0. A lag period of 5–10 days before the onset of growth was observed with mannitol, but no lag was observed with glucose. In addition, growth on mannitol after 4 weeks was greater if the inoculum had previously been grown on mannitol than if it had previously grown on glucose. These observations suggest adaptation of the fungus to mannitol. The optimum temperatures for growth of the fungus on mannitol and glucose were 27 and 21 °C, respectively. At 23 °C, the ability of the fungus to form ectomycorrhizae on Pinus mugo seedlings was low, regardless of whether the inoculum had been grown on mannitol or on glucose. At 33 °C, however, infectivity was substantially increased. At the higher temperature, mannitol and glucose grown inoculum caused 35 and 55% of the short roots to become infected, respectively.
Algae of selected continental and maritime bogs in North America
Authors: Yung Ying-Kit , Stokes Pamela , Gorham Eville
Published: October 2007

Algal taxa (281) were identified from 31 ombrotrophic bogs and 3 weakly minerotrophic fens from Manitoba to Newfoundland. Species richness increases from continental to maritime and coastal bogs, mainly as a result of an increase in Chlorophyta, especially Desmidiaceae. Species richness is related to (i) availability of open water and (ii) habitat types. Desmids shift from Actinotaenium, Penium, and Cylindrocystis in continental bogs to Euastrum, Staurastrum, and Arthrodesmus in maritime and coastal bogs. Diatoms shift likewise from Eunotia, Navicula, and Pinnularia to Frustulia, Tabellaria, and Pinnularia. Diatom species richness is similar in continental, maritime, and coastal sites. Algal biomass is usually dominated by filamentous Zygnematales, Ulotrichales, Oedogoniales, and Nostocales. Abundant Cyanophyta with heterocysts may be significant for nitrogen budgets in bogs.
Ecological relationships of wild rice, Zizania aquatica. 7. Sediment nutrient depletion following introduction of wild rice to a shallow boreal lake
Authors: Keenan T. J. , Lee P. F.
Published: September 2007

A marked decline in wild rice production was observed 5 years after a northwestern Ontario lake was seeded. A paired-comparison t-test detrmined that sediment manganese, zinc, copper, magnesium, and potassium had all declined in concentration, but nitrogen showed the greatest decrease. Discriminant analysis indicated that sediment nitrogen contributed most to a function distinguishing between years. A controlled experiment using several fertilizer formulations also found that addition of nitrogen to sediment from the lake promoted the greatest increase in wild rice growth. Changes in distribution of wild rice and in values of water depth, organic matter, dry weight of other macrophytes, and wild rice density and dry weight indicated that the decrease in sediment nitrogen was probably associated with movement of wild rice straw within the lake.
Effect of microorganisms on the aggressiveness of Bipolaris sorokiniana
Authors: Arora D. K.
Published: September 2007

Aggressiveness of conidia of Bipolaris sorokiniana (Sacc.) Shoemaker on wheat seedlings was reduced after 30 days of incubation on sterilized soil inoculated with microorganisms. The effect was greater with bacteria than with fungi or actinomycetes. Recovery of aggressiveness occurred when stressed conidia were incubated with nutrients. With increasing stress a longer period of incubation was needed for recovery. The 14C exudation from conidia was greater in unsterilized soil than in soil containing specific microorganisms. Exudation from conidia was inversely related to aggressiveness and germination.
Growth dynamics of cotton-grass (Eriophorum vaginatum)
Authors: Kummerow Jochen , Mills James N. , Ellis Barbara A. , Kummerow Andre
Published: September 2007

Root and leaf growth of the arctic sedge Eriophorum vaginatum L. were studied from early spring (June 7) to early fall (August 7) in the foothills of the Brooks Range in northern Alaska. The observations were designed to test the hypothesis that root and leaf growth occur at similar rates. The results confirmed this hypothesis. The root/leaf biomass ratio remained constant over the growing season. Thus, root biomass can be estimated based on harvested leaf biomass. It was also shown that root and leaf surface areas can be calculated from the respective biomass values. However, changes in the specific weights of leaves and roots over the growing season would affect the accuracy of root biomass or root surface area predictions.
Stratégie de tolérance au vent chez Salix uva-ursi, une espèce de la toundra du Nouveau-Québec (Canada)
Authors: Bélisle Luc , Maillette Lucie
Published: September 2007

Salix uva-ursi Pursh is a prostrate shrub typical of windy arctic–alpine tundra sites of eastern North America. According to Grime's thesis, plants living in growth-limiting conditions should satisfy the following criteria: (1) limited growth rate, (2) extended individual longevity, (3) reduced allocation to reproduction, (4) infrequent reproduction, (5) regeneration by vegetative multiplication or seedling bank rather man seed bank, (6) reduced plasticity, and (7) persistent leaves. Salix uva-ursi displays a few of these criteria (1, 2, 4) and is capable of layering (5). However, contrary to Grime's conditions (3, 6, and 5, respectively), allocation of annual biomass to reproduction is considerable, structure is variable, depending on wind exposure, and a seedling bank is absent and regeneration depends in part on a large number of small, wind-dispersed seeds. Thus S. uva-ursi takes advantage of wind, which is usually a limiting factor, to reach the few favorable microhabitats of an otherwise inhospitable environment. Finally, the leaves of S. uva-ursi die each fall (contrary to 7) but remain attached to the plant for several years. This may increase the boundary layer in winter and allow for protection against snow erosion. Salix uva-ursi dominates sites with very high levels of stress but its biology is not always consistent with Grime's predictions of the stress tolerance strategy.
Mycosphaerella mycopappi sp.aov. and its anamorphs on leaves of Acer macrophyllum
Authors: Funk A. , Dorworth C. E.
Published: September 2007

Mycosphaerella mycopappi sp.nov. was found in overwintered leaves of Acer macrophyilum Pursh occupying exclusively the zonate spots associated with Stigmina zilleri Funk of the previous autumn. Observations on new leaves in midsummer revealed the presence of Mycopappus aceris (Deam. & Barth.) Redhead & White in Stigmina-like leaf spots. Cultures made from all three morphs were compared and proved to be similar.