bluuebunny/crossref_metadata_2025 huggingface dataset:
Outcomes of dental fracture injury as related to laser Doppler flow measurements of pulpal blood‐flow level
Authors: Emshoff Rüdiger , Moschen Ivano , Oberrauch Andreas , Gerhard Stefan , Strobl Heinrich
Published: July 2008

Abstract –  Laser Doppler flowmetry (LDF) is a non‐invasive method to assess pulpal blood flow (PBF). Dental fracture injuries have been associated with significant PBF reduction The purpose of this study was: (i) to evaluate whether the severity of outcomes of dental fracture injuries may be related to LDF measurements of PBF, and (ii) to investigate whether outcomes of dental fracture injuries may predict PBF levels. The relationship between outcomes and PBF measurements was analyzed in 72 permanent maxillary incisors of 52 consecutive dental trauma patients. The diagnostic outcome group comprised 72 incisors with a type I (absence of sensitivity, periapical radiolucency, and grey discoloration of crown) (n = 42), type II (loss of sensitivity) (n = 16), or type III (loss of sensitivity, periapical radiolucency, and/or grey discoloration of crown) diagnosis. At each session, when an injured permanent maxillary incisor was recorded, a contralateral homologous tooth was used as a control. An ordinal stepwise regression was completed to assess the degree of association between PBF measurements and diagnostic outcomes. A logistic regression analysis was used to compute the odds ratios for the outcome features for incisor non‐injury controls vs two outcome groups: type II (n = 16) and type III (n = 14). PBF measurements that were significantly associated with more severe outcome were PBF levels of ≤6 perfusion units (PU) (106.70 odds ratio) (P = 0.000). Significant increase in the risk of a PBF level of ≤6 PU occurred with a type III outcome (32.49 odds ratio) (P = 0.004). PBF measurements were related to the severity of adverse outcomes. Diagnoses of treatment outcomes predicted the presence of specific PBF levels.
Vascular endothelial growth factor (VEGF) response to dental trauma: a preliminary study in rats
Authors: Lin Shaul , Roguin Ariel , Metzger Zvi , Levin Liran
Published: July 2008

Abstract –  Background: Successful periodontal healing and pulpal revascularization after trauma may be age‐related. After dental trauma, age‐related impaired angiogenesis may play a role in the revascularization rate during the healing process. Objectives: The aim of the present preliminary in vivo study was to detect the presence of vascular endothelial growth factor (VEGF) in venous and whole blood from the alveolar socket immediately post‐tooth extraction. Materials and methods: The study consisted of 16 Wistar rats divided into two groups: eight young (6 weeks) with incomplete root development and open apices, and eight adult (4 months) with complete root development. One first mandibular molar was extracted and whole blood from the alveolar socket collected immediately and at 5, 10 and 15 min post‐extraction. Venous blood samples were collected immediately pre‐ and 24‐h post‐extraction. All samples were tested for VEGF. Results: Increased VEGF levels were found in the venous blood 24 h post‐extraction, with a significant difference in the young rats (P < 0.05). The increased VEGF serum concentration in the young rats was significantly higher (12.2 ± 4.6 pg ml−1, median 12.1) than that in the adult rats (7.6 ± 3.8 pg ml−1, median 6.7) (P = 0.037). VEGF at the extraction site was not significantly different at 15 min post‐extraction. At the extraction site, there was no significant difference of VEGF concentration between young and adult rats. Conclusions: Young rats had higher post‐extraction serum VEGF levels, which may contribute to the healing process after dental trauma.
Biomechanical model of incisor avulsion: a preliminary report
Authors: Miura Jiro , Maeda Yoshinobu
Published: July 2008

Abstract –  The aim of the current study was to produce a two‐dimensional finite‐element model (FEM) of a maxillary incisor being palatally displaced with sufficient force to result in avulsion. The viscosity and elastic coefficient of bone were chosen from previous studies to model the properties of the periodontal complex. A ramped impact of 100 N was applied over a period of 1.5 ms in the direction perpendicular to the labial surface of the incisor model. Changes in the periodontal ligament (PDL) length (elongation and compression) started immediately after the impact and progressed to strain developing in the alveolar bone. In accordance with these changes in the PDL length, the tooth started to rotate with the center of rotation located at the edge of the palatal alveolar bone, combining the stress concentrations at the labial and cervical edges of the bone. When the elongation reached the designated limit, PDL disconnection occurred, leading to tooth avulsion. The resulting two‐dimensional FEM is capable of modeling changes in the PDL length and compression, rotation and avulsion.
Survival of 534 incisors after intra‐alveolar root fracture in patients aged 7–17 years
Authors: Cvek Miomir , Tsilingaridis Georgios , Andreasen Jens Ove
Published: July 2008

Abstract –  The purpose of the study was to evaluate and assess the survival rate of 534 root fractured teeth, including factors that may affect the survival rate but were not included in previous long‐term studies. Location of fracture was registered as in the cervical, cervical/middle, middle and apical one‐third of the root, and root development was categorized into five stages. Altogether, 383 (78%) showed healing of the fracture, with either formation of hard tissue or interposition of soft tissue between the fragments. In these teeth, no significant difference was found between positions in the root or types of healing. In 325 teeth, the healing remained unchanged throughout the control period, while 58 teeth showed a posthealing complication. A new injury occurred in 47 teeth; in 21 of these, the injury healed spontaneously, in four after endodontic treatment. Increased mobility of the coronal fragment was recorded for 32 teeth, and in 11 of these, the looseness of the fragment was so pronounced that the teeth had to be extracted. No healing, i.e. radiolucency in the alveolar bone, adjacent to fracture, took place in 109 teeth (22%). Of these teeth, 34 were extracted during the observation time while 75 (69%) showed healing after endodontic therapy. At the final assessment of survival (including all parameters) of 534 root fractured teeth, 425 (80%) showed survival and 109 (20%) were extracted during the observation period. It was concluded that the survival of root‐fractured teeth was high for up to10 years of observation (mean = 63 months). The highest frequency of tooth loss (70%) was found in 77 teeth with horizontal fractures restricted to the cervical part of the root. When these teeth were excluded, the frequency of survival in remaining teeth rose to 88%.
Migrant Interactions With Elderly Parents in Rural Cambodia and Thailand
Authors: Zimmer Zachary , Korinek Kim , Knodel John , Chayovan Napaporn
Published: July 2008

This paper examines interactions between older adults living in rural areas of Thailand and Cambodia and their adult children. Thai data come from the Survey of the Welfare of the Elderly (N= 3,202 older adults and 17,517 adult children). Cambodia data are from the Survey of the Elderly in Cambodia (N= 777 older adults and 3,751 adult children). Results indicate that older adults in rural areas are not being abandoned, and supportive expressions such as visits and provision of material goods depend on living proximity, characteristics that relate to the needs and dependency of the older adult, and the life circumstances of adult children. These findings support an extension of an altruistic perspective that incorporates notions of vulnerability of older adults.
Intergenerational Support and Depression Among Elders in Rural China: Do Daughters‐In‐Law Matter?
Authors: Cong Zhen , Silverstein Merril
Published: July 2008

This study examined the influence of intergenerational assistance with household chores and personal care from sons, daughters, and daughters‐in‐law on the depressive symptoms of older adults in rural China. The sample derived from rural Anhui Province, a region with a strong hierarchy of support preferences that leads with sons and their families. We used data from a random sample of 1,281 adults aged 60 and over, who were interviewed in 2001 and 2003. Analyses indicated that depressive symptoms were usually reduced by assistance from daughters‐in‐law and increased sometimes when such support was from sons. These relationships held most strongly when mothers coresided with their daughters‐in‐law. This research suggests that the benefits of intergenerational support are conditional on culturally prescribed expectations.
He Said, She Said: Comparing Mother and Father Reports of Father Involvement
Authors: Mikelson Kelly S.
Published: July 2008

This study compares mother and father reports of fathers’ involvement, including frequency of involvement and emotional involvement, with their child and examines demographic and social factors that predict the discrepancy in father and mother reports. Using matched pairs of parents (n = 2,058) from the Fragile Families and Child Wellbeing data, this study finds that father and mother reports of fathers’ involvement differ significantly. For example, fathers report spending 17.6% more time engaged in 11 activities with their young children than mothers report. How parental disagreement is measured yields starkly different results given the underlying distribution of these data. The paper also provides insight into what data issues should concern researchers studying fathers’ involvement and contributes to the growing literature on fathers’ involvement.
Family Structure History and Adolescent Romance
Authors: Cavanagh Shannon E. , Crissey Sarah R. , Raley R. Kelly
Published: July 2008

This study examined the association between family structure history and adolescent romance. Using a national sample drawn from Add Health (N= 13,570), family structure at Wave I was associated with the likelihood that adolescents were involved in a romantic relationship at Wave II and, among those in a relationship, the number of relationships they had since Wave I. Cumulative family instability and its timing were also associated with these outcomes and largely drove the family structure effects. Gender and age interactions suggest that experiences of family instability were more consequential to the romantic lives of boys and younger teens.
The Effect of Family Communication Patterns on Adopted Adolescent Adjustment
Authors: Rueter Martha A. , Koerner Ascan F.
Published: July 2008

Adoption and family communication both affect adolescent adjustment. We proposed that adoption status and family communication interact such that adopted adolescents in families with certain communication patterns are at greater risk for adjustment problems. We tested this hypothesis using a community‐based sample of 384 adoptive and 208 nonadoptive families. Adolescents in these families were, on average, 16 years of age. The results supported our hypothesis. Adopted adolescents were at significantly greater risk for adjustment problems compared to nonadopted adolescents in families that emphasized conformity orientation without conversation orientation and in families that emphasized neither conformity nor conversation orientation. Adolescents in families emphasizing conversation orientation were at lower risk for adjustment problems, regardless of adoption status.
One’s Enough for Now: Children, Disability, and the Subsequent Childbearing of Mothers
Authors: MacInnes Maryhelen D.
Published: July 2008

This mixed‐methods study explores the subsequent childbearing of mothers whose firstborn children have disabilities. I make use of matched data from the 1993 NHIS ‐ 1995 NSFG (N= 4,468) to determine the effects of child disability on the hazard of a second birth and draw on a series of 24 in‐depth interviews that explore the lived experience of raising children with disabilities. My findings suggest that mothers whose firstborn children are disabled have a lower hazard of a second birth. This reduction stems from mothers’ recognition that children with disabilities have extensive needs and that, in order to meet those needs and maximize their potential, they need to make strategic choices such as delaying subsequent childbearing.
Mental Illness as a Barrier to Marriage Among Unmarried Mothers
Authors: Teitler Julien O. , Reichman Nancy E.
Published: July 2008

This study explores how mental illness shapes transitions to marriage among unwed mothers using augmented data from the Fragile Families and Child Wellbeing study (N= 2,351). We estimate proportional hazard models to assess the effects of mental illness on the likelihood of marriage over a 5‐year period following a nonmarital birth. Diagnosed mental illness was obtained from the survey respondents’ prenatal medical records. We find that mothers with mental illness are about two thirds as likely as mothers without mental illness to marry, even after controlling for demographic characteristics, and that human capital, relationship quality, partner selection, and substance abuse appear to explain only a small proportion of the effect of mental illness on marriage.
Interracial‐Interethnic Unions and Fertility in the United States
Authors: Fu Vincent Kang
Published: July 2008

How does the fertility of interracial and interethnic couples compare to the fertility of endogamous couples? If exogamous couples have transcended the boundary between them, then exogamy should not affect fertility. Alternatively, opposition to the relationship from the couple’s family and friends may reduce fertility. This study uses 2000 – 2005 American Community Survey data on married (n = 272,336) and cohabiting (n = 48,769) couples to compare the fertility of endogamous and exogamous couples. Interracial and interethnic partnering do not affect fertility for cohabiting, Black‐White, Mexican‐White, and Puerto Rican‐White intermarried couples, but it does reduce fertility in Chinese‐White and Asian Indian‐White intermarriages. These results are largely consistent with the argument that intermarried couples have transcended group boundaries.
The Roles of Soil Characteristics and Toxin Adsorption in Avian Geophagy
Authors: Brightsmith Donald J. , Taylor John , Phillips Timothy D.
Published: July 2008

Geophagy, the intentional ingestion of soil, is a widespread phenomenon whose function is still debated. Recent studies suggest that consumed soils adsorb dietary toxins and provide sodium. However, quantification of soil choice has been absent from most studies, prohibiting the direct comparison of soil use and characteristics. To determine correlates among bird use and soil characteristics, we analyze physical structure, mineral composition, and alkaloid adsorption (14 soil characteristics in total) for 22 soil samples from a riverbank ‘clay lick’ used by macaws and parrots (family Psittacidae) in Amazon lowland forests in the Tambopata region of southeastern Peru. We quantified bird preferences through photographic mapping. Mineral concentrations were determined using analyses designed to approximate the mineral availability in the vertebrate stomach. The sodium levels in the soil were much higher than in food plants consumed by parrots in this region. Both adsorption of quinine, the model alkaloid used, and sodium concentration correlated significantly with bird use. Sodium explained a much higher percentage of the variation in bird use than quinine adsorption. However, the analyses were complicated by the high degree of correlation among soil variables: clay percentage and sodium concentration were highly correlated with each other and with bird use, making it impossible to determine which of these may have the greater contribution to bird preference. The results suggest that the soils consumed provide an important source of dietary sodium and adsorb alkaloid toxins.
The Vascular Disrupting Agent 5,6‐Dimethylxanthenone‐4‐Acetic Acid Improves the Antitumor Efficacy and Shortens Treatment Time Associated with Photochlor‐sensitized Photodynamic Therapy In Vivo
Authors: Seshadri Mukund , Bellnier David A.
Published: July 2008

In this report, we examined the antitumor activity of photodynamic therapy (PDT) in combination with 5,6‐dimethylxanthenone‐4‐acetic acid (DMXAA), a vascular disrupting agent currently undergoing clinical evaluation. BALB/c mice bearing subcutaneous CT‐26 colon carcinomas were treated with PDT using the second‐generation chlorin‐based sensitizer, 2‐[1‐hexyloxyethyl]‐2‐devinyl pyropheophorbide‐a (Photochlor) with or without DMXAA. Long‐term (60‐days) treatment outcome, induction of tumor necrosis factor‐alpha (TNF‐α) and interleukin‐6 (IL‐6), vascular damage (microvessel density, MVD) were evaluated as endpoints. In addition, treatment selectivity was evaluated using magnetic resonance imaging (MRI) and the foot response assay. A highly synergistic interaction was observed with the combination of low‐dose DMXAA and PDT (48 J cm−2 at 112 mW cm−2) resulting in ∼60% long‐term cures. The duration of the PDT session for this combination therapy protocol was only 7 min, while the duration of a monotherapy PDT session, selected to yield the equivalent cure rate, was 152 min. MRI showed markedly less peritumoral edema after DMXAA + short‐duration PDT compared with long‐duration PDT monotherapy. Similarly, DMXAA + PDT caused significantly less phototoxicity to normal mouse foot tissue than PDT alone. Increased induction of cytokines TNF‐α and IL‐6 (P < 0.001) was observed at 4 h followed by extensive vascular damage, demonstrated by a significant reduction in MVD at 24 h after combination treatment. In conclusion, Photochlor‐sensitized PDT in combination with DMXAA exhibits superior efficacy and improved selectivity with clinically feasible illumination schemes. Clinical evaluation of this novel combination strategy is currently being planned.
Absorption Spectra of Human Skin In Vivo in the Ultraviolet Wavelength Range Measured by Optoacoustics
Authors: Meinhardt Merve , Krebs Ronald , Anders Angelika , Heinrich Ulrike , Tronnier Hagen
Published: July 2008

Knowledge of the optical properties of human skin in the ultraviolet range is fundamental for photobiologic research. However, optical properties of human skin in the ultraviolet spectral range have so far mainly been measured ex vivo. We have determined the absorption spectra of human skin in vivo in the wavelength range from 290 to 341 nm in 3 nm steps using laser optoacoustics. In this technique, optical properties are derived from the pressure profile generated by absorbed light energy in the sample. In a study on 20 subjects belonging to phototypes I–IV, we studied the optical properties at the volar and dorsal aspect of the forearm as well as on the thenar. Analysis of the measured absorption spectra shows that comparable skin areas—like different sides of the forearm—have qualitatively similar optical characteristics. Still, the optical properties may vary substantially within the same area, probably due to the skin structure and inhomogeneities. Comparison of the spectra from different skin sites indicates that the spectral characteristics of the stratum corneum and its chromophores play an important role for the optical properties of human skin in vivo in the ultraviolet B range.
In Vitro Survival of Nonsmall Cell Lung Cancer Cells Following Combined Treatment with Ionizing Radiation and Photofrin‐mediated Photodynamic Therapy
Authors: Sharma Prachi , Farrell Thomas , Patterson Michael S. , Singh Gurmit , Wright James R. , Sur Ranjan , Rainbow Andrew J.
Published: July 2008

It has been suggested that combination high dose rate (HDR) intraluminal brachytherapy and photodynamic therapy (PDT) in nonsmall cell lung cancer (NSCLC) may improve efficacy of treatment, reduce toxicity and enhance quality of life for patients. To provide a cellular basis for this we examined the in vitro sensitivity of MRC5 normal lung fibroblasts and four NSCLC cell lines following HDR radiation, PDT and combined HDR radiation and PDT. HDR radiation was cobalt‐60 gamma rays (1.5–1.9 Gy min−1). For PDT treatment, cells were exposed to 2.5 μg mL−1 Photofrin for 18–24 h followed by light exposure (20 mW cm−2). For combined treatment cells were exposed to Photofrin and then either exposed to light and 15–30 min later exposed to HDR radiation or exposed to HDR radiation and 15–30 min later exposed to light. D37 values calculated from clonogenic survival curves indicated a six‐fold difference in HDR radiation sensitivity and an eight‐fold difference in PDT sensitivity. The effect of combined treatment was not significantly different from an additive effect of the individual treatment modalities for the NSCLC cells, but was significantly less than additive for the MRC5 cells. These results suggest an equivalent tumor cell kill may be possible at reduced systemic effects to patients.
What is your diagnosis? Pancytopenia in a dog
Authors: Williams Marjorie J. , Gardiner David , Seelig Davis , Olver Christine S.
Published: July 2008

Abstract: A 4‐year‐old male, castrated, mixed‐breed dog was presented to the Colorado State University Veterinary Teaching Hospital with a 1‐week history of polyuria, polydipsia, lethargy, fever, inappetence, weight loss, and soft mucoid stool. The dog was depressed and had pale, icteric mucous membranes. Results of a CBC included normocytic, normochromic, nonregenerative anemia, neutropenia, and thrombocytopenia, with 43% blast cells (200/μL), many of which contained fine azurophilic granules. Cytologic evaluation of the bone marrow aspirates revealed mild granulocytic hyperplasia that appeared to be left‐shifted in an apparent maturation arrest. A large population of blast cells comprised 35% of nucleated cells; the blasts had high nuclear to cytoplasmic ratios, deeply basophilic cytoplasm with vacuoles, and prominent nucleoli. Most cells also contained many fine azurophilic granules clustered in the paranuclear region. At necropsy, neoplastic cells were abundant in the bone marrow. Immunohistochemically the cells expressed CD3ɛ, and an oligoclonal T‐cell rearrangement was found. The diagnosis was proliferative disorder of CD3+ granular lymphocytes, with associated pancytopenia. Because the blast cells were morphologically similar to myeloblasts and immunohistochemistry was required to confirm the diagnosis, T‐cell lymphoproliferative disease should be considered in dogs with pancytopenia presenting with similar clinical features.
Passive Balancing of Rotor Systems Using Pendulum Balancers
Authors: Horvath Roland , Flowers George T. , Fausz Jerry
Published: July 2008

Passive balancing techniques have received a great deal of attention in recent literature, with much of this work focused on ball balancer systems. However, for certain applications, balancing systems that use pendulums rather than rolling balls may offer distinctly improved balancing precision. This investigation seeks to provide additional insight into the performance and expected behavior of such systems. A simulation model is developed for a pendulum balancer system with isotropic supports and analyzed in detail. The influence of shaft location and friction on balancing effectiveness is considered and evaluated. In this regard, the dynamic characteristics of a pendulum balancer system are analyzed and compared to a similar ball balancer system. The conclusions and observations from the analysis and simulation studies are demonstrated and tested in a series of experimental studies.
Vibrations of an Asymmetrical Shaft With Gravity and Nonlinear Spring Characteristics (Isolated Resonances and Internal Resonances)
Authors: Ishida Yukio , Liu Jun , Inoue Tsuyoshi , Suzuki Akihiro
Published: July 2008

An asymmetrical shaft supported by single-row deep groove ball bearings with clearance has nonlinear spring characteristics, rotating stiffness difference in shaft, and static stiffness difference in support at the shaft ends. When an asymmetrical rotor is supported horizontally, a harmonic excitation due to the unbalance and a double frequency excitation due to the coexistence of gravity and shaft asymmetry work simultaneously. As a result, this system becomes a nonlinear parametrically excited system with multiple periodic excitation forces. In this paper, nonlinear forced vibrations and parametrically excited vibrations are investigated theoretically and experimentally. Vibration characteristics of both isolated resonances and internal resonances are studied.
Modeling and Computation for the High-Speed Rotating Flexible Structure
Authors: Huang Yong-an , Yin Zhou-ping , Xiong You-lun
Published: July 2008

This paper is presented to improve the modeling accuracy and the computational stability for a high-speed rotating flexible structure. The differential governing equations are derived based on the first-order approximation coupling (FOAC) model theory in the framework of the generalized Hamiltonian principle. The semi-discrete model is obtained by the finite element method, and a new shape function based on FOAC is established for the piezoelectric layers. To increase the efficiency, accuracy, and stability of computation, first, the second-order half-implicit symplectic Runge–Kutta method is presented to keep the computational stability of the numerical simulation in a long period of time. Then, the idea of a precise integration method is introduced into the symplectic geometric algorithm. An improved symplectic precise integration method is developed to increase accuracy and efficiency. Several numerical examples are adopted to show the promise of the modeling and the computational method.
Identification of Plate Boundary Forces From Measured Displacements
Authors: Chesne Simon , Pezerat Charles , Guyader Jean-Louis
Published: July 2008

This work deals with the identification of forces at plate boundaries, by measuring displacements only. Shear force and bending moment directly depend on different spatial derivatives of displacement at plate boundaries that can be approximated from measured displacements (finite differences, modal approach, etc.), but two major difficulties occur: Derivatives are highly sensitive to measurement errors and the usual methods used to obtain them are not well adapted to boundary points. In this paper, a mathematical approach is proposed to identify shear force at boundaries without any direct calculation of the displacement derivatives. The method is based on the weak form of the plate equation of motion and a test function satisfying particular boundary conditions. Following the description of the technique and the definition of the test function that permits the identification at one boundary point, numerical simulation results, including the effects of noise on displacements, are provided in order to establish the spatial and frequency limits of this method.
Dynamic Beam Modification Using Dimples
Authors: Cheng W. N. , Cheng C. C. , Koopmann G. H.
Published: July 2008

In this paper, a design method to modify the vibration characteristics of a beam by creating cylindrical dimples on its surface is investigated. In particular, the vibration response of a beam with several dimples is formulated using the impedance method. The dimpled beam is divided into two kinds of structural segments: one, a curved beam that is modeled as the dimple and the other, a straight beam. The frequency equation is derived by assembling the impedance of each structure segment based on conditions of force equilibrium and velocity compatibility. Then a novel method for shifting the natural frequencies of a beam to preassigned values by creating cylindrical dimples on this structure is introduced. The dimple size and its location on the structure can be determined analytically, so the time consuming process using the traditional optimal search method is thereby avoided. Several examples using this technique are demonstrated.
Identification of Cracks in Beams With Auxiliary Mass Spatial Probing by Stationary Wavelet Transform
Authors: Zhong Shuncong , Oyadiji S. Olutunde
Published: July 2008

This paper proposes a new approach based on auxiliary mass spatial probing by stationary wavelet transform (SWT) to provide a method for crack detection in beamlike structure. SWT can provide accurate estimation of the variances at each scale and facilitate the identification of salient features in a signal. The natural frequencies of a damaged beam with a traversing auxiliary mass change due to the change in flexibility and inertia of the beam as the auxiliary mass is traversed along the beam. Therefore, the auxiliary mass can enhance the effects of the crack on the dynamics of the beam and, therefore, facilitate the identification and location of damage in the beam. That is, the auxiliary mass can be used to probe the dynamic characteristic of the beam by traversing the mass from one end of the beam to the other. However, it is difficult to locate the crack directly from the graphical plot of the natural frequency versus axial location of auxiliary mass. This curve of the natural frequencies can be decomposed by SWT into a smooth, low order curve, called approximation coefficient, and a wavy, high order curve called the detail coefficient, which includes crack information that is useful for damage detection. The modal responses of the damaged simply supported beams with auxiliary mass used are computed using the finite element method (FEM). Sixty-four cases are studied using FEM and SWT. The efficiency and practicability of the proposed method is illustrated via experimental testing. The effects of crack depth, crack location, auxiliary mass, and spatial probing interval are investigated. From the simulated and experimental results, the efficiency of the proposed method is demonstrated.
Multiobjective Collaborative Robust Optimization With Interval Uncertainty and Interdisciplinary Uncertainty Propagation
Authors: Li M. , Azarm S.
Published: July 2008

We present a new solution approach for multidisciplinary design optimization (MDO) problems that, for the first time in literature, has all of the following characteristics: Each discipline has multiple objectives and constraints with mixed continuous-discrete variables; uncertainty exists in parameters and as a result, uncertainty propagation exists within and across disciplines; probability distributions of uncertain parameters are not available but their interval of uncertainty is known; and disciplines can be fully (two-way) coupled. The proposed multiobjective collaborative robust optimization (McRO) approach uses a multiobjective genetic algorithm as an optimizer. McRO obtains solutions that are as best as possible in a multiobjective and multidisciplinary sense. Moreover, for McRO solutions, the variation of objective and/or constraint functions can be kept within an acceptable range. McRO includes a technique for interdisciplinary uncertainty propagation. The approach can be used for robust optimization of MDO problems with multiple objectives, or constraints, or both together at system and subsystem levels. Results from an application of McRO to a numerical and an engineering example are presented. It is concluded that McRO can solve fully coupled MDO problems with interval uncertainty and obtain solutions that are comparable to a single-disciplinary robust optimization approach.
Machine-Tool Settings to Reduce the Sensitivity of Spiral Bevel Gears to Tooth Errors and Misalignments
Authors: Simon Vilmos V.
Published: July 2008

The method for loaded tooth contact analysis is applied for the investigation of the combined influence of machine-tool settings for pinion teeth finishing and misalignments of the mating members on load distribution and transmission errors in mismatched spiral bevel gears. By using the corresponding computer program, the influence of pinion’s offset and axial adjustment error, angular position error of the pinion axis, tooth spacing error, and machine-tool setting correction for pinion teeth finishing, on tooth contact pressure, tooth root stresses, and angular displacement of the driven gear member from the theoretically exact position based on the ratio of the numbers of teeth is investigated. On the basis of the obtained results, the optimal combination of machine-tool settings is determined. By the use of this set of machine-tool settings, the maximum tooth contact pressure and transmission errors can be significantly reduced. However, in some cases, by the use of appropriate machine-tool settings for the reduction of tooth contact pressure, the angular displacement of the driven gear increases. Therefore, different optimized combinations of machine-tool settings for pinion tooth finishing for the reduction of the sensitivity of gears to misalignments in regard to maximum tooth contact pressure and transmission errors should be applied. By the use of the combination of machine-tool settings to reduce the sensitivity of gears to misalignments in regard to transmission errors, a slight reduction of maximal tooth contact pressure is achieved, too.
Application of a Ground Beam-Joint Topology Optimization Method for Multi-Piece Frame Structure Design
Authors: Kim Myung-Jin , Jang Gang-Won , Kim Yoon Young
Published: July 2008

When a multipiece frame structure is designed, not only its topological layout but also assembly locations should be determined. This paper presents a compliance-minimizing topology optimization technique to determine an optimal layout configuration and to suggest candidate assembly locations. The technique employs a ground beam-joint model and places candidate assembly joints where the values of joint stiffness are relatively small. The zero-length joint elements have varying stiffness controlled by real-valued design variables. Because joint stiffness values at the converged state can be utilized to select candidate assembly locations along with their strengths, the technique is extremely useful in multipiece frame structure design. Because structural properties of ground beams can have only discrete values or remain unchanged for optimization process, no poststructural modification is required in an actual manufacturing step.
Inverse problem and Bertrand’s theorem
Authors: Grandati Yves , Bérard Alain , Ménas Ferhat
Published: July 2008

Bertrand’s theorem is formulated as the solution of an inverse problem for classical one-dimensional motion. We show that the solutions of this problem, if suitably restricted, can be obtained by solving an elementary equation. This approach provides a compact and elegant proof of Bertrand’s theorem.
Examples of the zeroth theorem of the history of science
Authors: Jackson J. D.
Published: July 2008

The zeroth theorem of the history of science (enunciated by E. P. Fischer) and widely known in the mathematics community as Arnol’d’s principle states that a discovery (rule, regularity, or insight) named after someone often did not originate with that person. I present five examples from physics: the Lorentz condition ∂μAμ=0 defining the Lorentz gauge of the electromagnetic potentials, the Dirac delta function δ(x), the Schumann resonances of the Earth-ionosphere cavity, the Weizsäcker–Williams method of virtual quanta, and the Bargmann, Michel, and Telegdi equation of spin dynamics. I give sketches of both the actual and reputed discoverers and quote from their “discovery” publications.
A simple demonstration of frustrated total internal reflection
Authors: Vörös Zoltán , Johnsen Rainer
Published: July 2008

We describe a quantitative and inexpensive method of demonstrating frustrated total internal reflection based on the attenuation of a laser beam through a wedge-shaped air gap between two glass prisms. An advantage of this method is that the thickness of the air gap can be determined by observing interference effects with only a slight modification of the setup. The experiment avoids the need to employ high-precision translation stages as is often the case in standard demonstrations of frustrated total internal reflection.
Paradoxical pop-ups: Why are they difficult to catch?
Authors: McBeath Michael K. , Nathan Alan M. , Bahill A. Terry , Baldwin David G.
Published: July 2008

Professional baseball players occasionally find it difficult to gracefully approach seemingly routine pop-ups. We describe a set of towering pop-ups with trajectories that exhibit cusps and loops near the apex. For a normal fly ball the horizontal velocity continuously decreases due to drag caused by air resistance. For pop-ups the Magnus force is larger than the drag force. In these cases the horizontal velocity initially decreases like a normal fly ball, but after the apex, the Magnus force accelerates the horizontal motion. We refer to this class of pop-ups as paradoxical because they appear to misinform the typically robust optical control strategies used by fielders and lead to systematic vacillation in running paths, especially when a trajectory terminates near the fielder. Former major league infielders confirm that our model agrees with their experiences.
Video through a light guide
Authors: Kraftmakher Yaakov
Published: July 2008

Demonstrations are discussed to illustrate some basic principles of television transmission and reception. The aim of these demonstrations is to promote student understanding of how a picture is converted into an electrical signal, sent to a remote receiver, and correctly reproduced there. The demonstration setup includes a video camera, a light emitting diode, a light guide, a photodiode, and a video monitor. Electrical production of visual images is also discussed.
Evidence of wave front folding of sonic booms by a laboratory-scale deterministic experiment of shock waves in a heterogeneous medium
Authors: Ganjehi Lili , Marchiano Régis , Coulouvrat François , Thomas Jean-Louis
Published: July 2008

The influence of the planetary boundary layer on the sonic boom received at the ground level is known since the 1960s to be of major importance. Sonic boom propagation in a turbulent medium is characterized by an increase of the mean rise time and a huge variability. An experiment is conducted at a 1:100 000 scale in water to investigate ultrasonic shock wave interaction with a single heterogeneity. The experiment shows a very good scaling with sonic boom, concerning the size of the heterogeneities, the wave amplitude, and the rise time of the incident wave. The wave front folding associated with local focusing, and its link to the increase of the rise time, are evidenced by the experiment. The observed amplification of the peak pressure (by a factor up to 2), and increase of the rise time (by up to about one magnitude order), are in qualitative agreement with sonic boom observations. A nonlinear parabolic model is compared favorably to the experiment on axis, though the paraxial approximation turns out less precise off axis. Simulations are finally used to discriminate between nonlinear and linear propagations, showing nonlinearities affect mostly the higher harmonics that are in the audible range for sonic booms.
Uncertainty estimation in simultaneous Bayesian tracking and environmental inversion
Authors: Dosso Stan E. , Wilmut Michael J.
Published: July 2008

This paper develops a Bayesian approach for two related inverse problems: tracking an acoustic source when ocean environmental parameters are unknown, and determining environmental parameters using acoustic data from an unknown (moving) source. The formulation considers source and environmental parameters as unknown random variables constrained by noisy acoustic data and by prior information on parameter values (e.g., physical limits for environmental properties) and on inter-parameter relationships (limits on radial and vertical source speed). The goal is not simply to estimate parameter values, but to rigorously determine parameter uncertainty distributions, thereby quantifying the information content of the data/prior to resolve source and environmental parameters. Results are presented as marginal posterior probability densities (PPDs) for environmental parameters and joint marginal PPDs for source ranges and depths. Given the numerically intensive inversion, an efficient Markov-chain Monte Carlo importance-sampling approach is developed which combines Metropolis and heat-bath Gibbs’ sampling, employs efficient proposal distributions based on a linearized PPD approximation, and considers nonunity sampling temperatures to ensure a complete parameter search. The approach is illustrated with two simulated examples representing tracking a quiet submerged source and geoacoustic inversion using noise from an unknown ship of opportunity. In both cases, source, seabed, and water-column parameters are unknown.
Analytical model for viscous damping and the spring force for perforated planar microstructures acting at both audible and ultrasonic frequencies
Authors: Homentcovschi Dorel , Miles Ronald N.
Published: July 2008

The paper presents a model for the squeezed film damping, the resistance of the holes, and the corresponding spring forces for a periodic perforated microstructure including the effects of compressibility, inertia, and rarefied gas. The viscous damping and spring forces are obtained by using the continuity equation. The analytical formula for the squeezed film damping is applied to analyze the response of an ultrasonic transducer. The inclusion of these effects in a model significantly improves the agreement with measured results. Finally, it is shown that the frequency dependence of the total damping and total spring force for a cell are very similar to those corresponding to a rectangular open microstructure without holes. A separate analysis reveals the importance of each particular correction. The most important is the compressibility correction; the inertia has to be considered only for determining the spring force and the damping force for sufficiently high frequencies.
Local vibration of an elastic plate and zero-group velocity Lamb modes
Authors: Prada Claire , Clorennec Dominique , Royer Daniel
Published: July 2008

Elastic plates or cylinders can support guided modes with zero group velocity (ZGV) at a nonzero value of the wave number. Using laser-based ultrasonic techniques, we experimentally investigate some fascinating properties of these ZGV modes: resonance and ringing effects, backward wave propagation, interference between backward and forward modes. Then, the conditions required for the existence of ZGV Lamb modes in isotropic plates are discussed. It is shown that these modes appear in a range of Poisson’s ratio about the value for which the cutoff frequency curves of modes belonging to the same family intercept, i.e., for a bulk wave velocity ratio equal to a rational number. An interpretation of this phenomenon in terms of a strong repulsion between a pair of modes having a different parity in the vicinity of the cutoff frequencies is given. Experiments performed with materials of various Poisson’s ratio demonstrate that the resonance spectrum of an unloaded elastic plate, locally excited by a laser pulse, is dominated by the ZGV Lamb modes.
Forward masking as a mechanism of automatic gain control in odontocete biosonar: A psychophysical study
Authors: Supin Alexander Ya. , Nachtigall Paul E. , Breese Marlee
Published: July 2008

In a false killer whale Pseudorca crassidens, echo perception thresholds were measured using a go/no-go psychophysical paradigm and one-up-one-down staircase procedure. Computer controlled echoes were electronically synthesized pulses that were played back through a transducer and triggered by whale emitted biosonar pulses. The echo amplitudes were proportional to biosonar pulse amplitudes; echo levels were specified in terms of the attenuation of the echo sound pressure level near the animal’s head relative to the source level of the biosonar pulses. With increasing echo delay, the thresholds (echo attenuation factor) decreased from −49.3dB at 2ms to −79.5dB at 16ms, with a regression slope of −9.5dB per delay doubling (−31.5dB per delay decade). At the longer delays, the threshold remained nearly constant around −80.4dB. Levels of emitted pulses slightly increased with delay prolongation (threshold decrease), with a regression slope of 3.2dB per delay doubling (10.7dB per delay decade). The echo threshold dependence on delay is interpreted as a release from forward masking by the preceding emitted pulse. This release may compensate for the echo level decrease with distance, thus keeping the echo sensation level for the animal near constant within a certain distance range.
Comodulation masking release in bottlenose dolphins (Tursiops truncatus)
Authors: Branstetter Brian K. , Finneran James J.
Published: July 2008

The acoustic environment of the bottlenose dolphin often consists of noise where energy across frequency regions is coherently modulated in time (e.g., ambient noise from snapping shrimp). However, most masking studies with dolphins have employed random Gaussian noise for estimating patterns of masked thresholds. The current study demonstrates a pattern of masking where temporally fluctuating comodulated noise produces lower masked thresholds (up to a 17dB difference) compared to Gaussian noise of the same spectral density level. Noise possessing wide bandwidths, low temporal modulation rates, and across-frequency temporal envelope coherency resulted in lower masked thresholds, a phenomenon known as comodulation masking release. The results are consistent with a model where dolphins compare temporal envelope information across auditory filters to aid in signal detection. Furthermore, results suggest conventional models of masking derived from experiments using random Gaussian noise may not generalize well to environmental noise that dolphins actually encounter.
Affect cues in vocalizations of the bat,Megaderma lyra, during agonistic interactions
Authors: Bastian Anna , Schmidt Sabine
Published: July 2008

Some features of emotional prosody in human speech may be traced back to affect cues in mammalian vocalizations. The present study addresses the question whether affect intensity, as expressed by the intensity of behavioral displays, is encoded in vocal cues, i.e., changes in the structure of associated calls, in bats, a group evolutionarily remote from primates. A frame-by-frame video analysis of 109 dyadic agonistic interactions recorded in approach situations was performed to categorize displays into two intensity levels based on a cost-benefit estimate. M. lyra showed graded visual displays accompanied by specific calls and response calls of the second bat. A sound analysis revealed systematic changes of call sequence parameters with display level. At the high intensity level, total call duration, number of syllables within a call, and the number of calls within a sequence were increased, while intervals between call syllables were decreased for both call types. In addition, the latency of the response call was shorter, and its main syllable–type durations and fundamental frequency were increased. These systematic changes of vocal parameters with affect intensity correspond to prosodic changes in human speech, suggesting that emotion-related acoustic cues are a common feature of vocal communication in mammals.