bluuebunny/crossref_metadata_2025 huggingface dataset:
Differential variations in Ca2+ entry, cytosolic Ca2+ and membrane capacitance upon steady or action potential depolarizing stimulation of bovine chromaffin cells
Authors: De Diego A. M. G. , Arnáiz‐Cot J. J. , Hernández‐Guijo J. M. , Gandía L. , García A. G.
Published: May 2008

Aims:  This study looks into the physiology of the exocytosis of catecholamines released by adrenal medullary chromaffin cells. We have comparatively explored the exocytotic responses elicited by two different patterns of depolarizing stimulation: the widely employed square depolarizing pulses (DPs) and trains of acetylcholine‐like action potentials (APs), likely the physiological mode of stimulation in the intact innervated adrenal medulla. APs were applied at 30 Hz, a frequency similar to that produced in a stressful situation.

Methods:  Patch‐clamp, cell membrane capacitance, single cell amperometry and fluorescence were the techniques used. The variations of calcium entry measured as the integral of the calcium current, cytosolic calcium (measured with the calcium‐sensitive fluorescent probe fluo‐4) and exo‐endocytosis (membrane capacitance variations) were the parameters measured.

Results:  Trains of AP depolarizations produced distinct responses compared to those of square depolarizations: (1) Calcium current amplitude decreased to a lesser extent along the AP train; (2) calcium entry and capacitance increments raised linearly with stimulation time whereas they deviated from linearity when square depolarizations were used; (3) slower activation and faster delayed decay phase of cytosolic calcium transients; (4) capacitance increments varied linearly with calcium entry with APs and deviated from linearity with longer depolarizations; (5) little endocytosis after stimulation with longer trains of APs and pronounced endocytosis with longer square depolarizations.

Conclusions:  Stimulation of chromaffin cells with trains of APs produced patterns of cytosolic calcium transients, exocytotic and endocytotic responses quite different from those elicited by the widely employed DPs. Our study is relevant from the methodological and physiological points of view.
Symposium on Diseases of Gats—IV. Feline Geriatrics
Authors: Joshua Joan O.
Published: May 2008

Abstract— A review of the problems associated with senile changes in the cat. Husbandry and management are discussed together with an outline of the conditions most frequently found in the aged animal in the various body systems.

Résumé— –Examen des problémes relatifs aux transformations séniles chez le chat. Discussion de la conduite à tenir et des soins à donner; apercu des troubles les plus fréquents rencontrés chez l'animal agé dans les différents systèmes de l'organisme.

Zusammenfassung— Ein Überblick über die mit den Altersveränderungen bei der Katin ez Verbindung stehenden Probleme. Es wird über die Zucht ünd Beaufsichtigung gesprochen und eine kurze Beschreibung der Zustände, die in den verschidenen Körpersystemen des gealterten Tieres am häufigsten auftreten, gegeben.
Multiple Myeloma in a Dog
Authors: PENNOCK PAUL , JÖNSSON LENNART , OLSSON STEN‐ERIK
Published: May 2008

Abstract— Multiple myeloma, a rare tumour of the hemopoietic system, is reported in a 10‐yr‐old female Poodle. Clinical signs included anemia, weakness, cachexia and pain when the dog was forced to move. Radiographs revealed demineralization of the skeleton; circular radiolucent foci were evident, especially in the long bones, and the sixth thoracic vertebra was compressed. Numerous cells of the plasma cell type were evident in bone marrow smears. Blood electrophoresis revealed hypergammaglobulinemia. Bence‐Jones proteinuria was not detected. The animal was destroyed and the clinical diagnosis confirmed at necropsy. Plasma cells were found in the bone marrow, liver, spleen and kidney. The bones were porous and numerous old fractures of the ribs and vertebrae were found.

Résumé— Un mytlome multiple, rare tumeur du systtme hématopoiésique est observée chez une caniche femelle de 10 am. Les signes cliniques incluent l'anémie, la faiblesse, la cachexie et des douleurs lorsque la chienne était obligée de faire des mouvements. Des radiographies ont révélé la déminéralisation du squelette; des foyers circulaires translucides aux Rayons X sont évidents, spécialement dans les os longs, et la sixième vertèbre toraxique est compressée. De nombreuses cellules du type des cellules à plasma étaient évidentes dans les macules de moelle. L'électrophorèse du sang a révélé de I'hypergammaglobulinémie. La présence Bence‐Jones de protéine dans l'urine n'a pas été détectée. L'animal a été détruit et le diagnostic clinique confirméà la nécropsie. Dies cellules de plasma ont été trouvées dans la moelle, le foie, la rate et les reins. Les os étaient poreux et de nombreuses vieilles fractures des cbtes et des vertèbres ont été trouvtes.

Zusammenfassuug—Berichterstattung über das Auftreten von multiplex Myelom, ein seltener Tumor im hämopoietischen System einer zehnjährigen Pundelhündin. Klinische Anzeichen umfassen Anämie, Schwäche, Kachexie und Schmerzen, wenn der Hund zur Bewegung gezwungen wurde. Radiogramme zeigten Demineralisierung des Skelettes; kreisförmige radiotransparente Herde traten besonders in den langen Knochen klar hervor und der sechste Brustwirbel war kompressed. Zahl‐reiche Zellen der Plasmakategorie wurden in Knochenmarkabstrichen augenscheinlich. Blut‐Elektrophoresis brachte Hyper‐Gammaglobulinamie zum Vorschein. Bence‐Jones Albuminurie wurde nicht gefunden. Das Tier wurde vernichtet und die klinische Diagnose bei der Obduktion bestätigt. Im Knochenmark, der Leber, der Milz und in den Nieren wurden Plasmazellen festgestellt. Die Knochen waren porös und zahlreiche alte Rippen‐und Rückenwirbelbrüche zeigten sich.
Two Syndromes in Young Dogs Caused by Toxoplasma Gondii
Authors: Drake J. C. , Hime J. M.
Published: May 2008

Abstract— —Two syndromes are described, one characterized by locomotor signs of varying severity affecting one or more limbs and causing partial or complete paralysis. The other characterized by an acute fulminating illness with death occurring within 48 hr of the appearance of initial symptoms, and possibly associated with the presence of distemper virus. In both syndromes, the examination of tissues microscopically showed the presence of Toxoplasma gondii either as free forms or cysts or both.
A Familial Canine Polyostotic Fibrous Dysplasia with Subperiosteal Cortical Defects
Authors: Carrig C. B. , Seawright A. A.
Published: May 2008

Abstract— —A cystic bone condition occurring in the distal metaphyses of the radius and/or ulna is reported in 1 male and 2 female Dobermann Pinscher siblings. The radiological and pathological features of the condition in the dogs were considered to be similar to those which characterise polyostotic fibrous dysplasia in man. The affected bones also showed subperiosteal cortical defects. Treatment by curettage at 7 months of age was successful in 2 dogs. The other dog remained untreated for comparison. It is suggested that the disease could be heritable in the American Dobermann Pinscher.

Résumé— —II a été observé un état de perte de substance osseuse localisée dam la partie distale des métaphyses du radius et ou du cubitus chez un mâle et 2 femelles Dobermann Pinscher de la même fratrie. On considère que les caractéristiques radiologiques et pathologiques de la maladie chez le chien sont identiques à celle de la dysplasie fibreuse polyostotique chez l'homme. Les os atteints montrent aussi des défauts corticaux subpériostiques. Le traitement par curetage à 1'âge de 7 mois fut un succès chez 2 chiens. A titre de comparaison, I'autre chien n'a pas été traité. Il semble que la maladie soit héréditaire chez le Pinscher Dobermann Américain.

Zusammenfassung— —Ein cystischer Knochenzustand in den distalen Metaphysen des Radius und/oder der Ulna wurde bei 1 männlichem und 2 weiblichen Dobermann‐Pinscher‐Abkömmlingen beobachtet. Die radiologischen und pathologischen Einzelheiten dieser Erscheinung bei den Hunden gleichen denen, die für die polyostotische fibröse Dysplasie des Menschen charakteristisch sind. Die befallenen Knochen zeigten auch subperiosteale corticale Defekte. Die Behandlung durch Curettage im Alter von sieben Monaten war bei 2 Hunden erfolgreich. Der andere Hund blieb zu Vergleichszwecken unbehandeIt. Es ist zu vermuten, dass diese Krankheit beim amerikanischen Doberrnann‐Pinscher vererblich ist.
Investigation of foraging habits and prey selection by humpback whales (Megaptera novaeangliae) using acoustic tags and concurrent fish surveys
Authors: Witteveen Briana H. , Foy Robert J. , Wynne Kate M. , Tremblay Yann
Published: May 2008

Abstract

Tags containing acoustic time‐depth transmitters (ATDT) were attached to four humpback whales near Kodiak, Alaska. Tags allowed for whale dive depths to be recorded in real time. Acoustic and mid‐water trawl surveys were conducted concurrent with tagging efforts within the study area to quantify available fish resources and describe potential prey selection by humpback whales. Recorded dives were grouped through visual assessment and t‐tests. Dives that indicated likely foraging occurred at a mean maximum depth of 106.2 m with 62% of dives occurring between 92 m and 120 m. Acoustic backscatter from fish surveys was attributed to potential humpback prey based on known target strength values and 10 net tows. Capelin comprised 84% of the total potential prey abundance in the region followed by age 0 (12%) and juvenile pollock (2%), and eulachon (<1%). Although horizontally segregated in the region, both capelin and age 0 pollock were distributed at depths exceeding 92 m with maximum abundance between 107 m and 120 m. The four‐tagged humpbacks were found to forage in areas with greatest capelin densities but bypassed areas of high age 0 pollock abundance. The location and diving behavior of tagged whales suggested that whales were favoring capelin over pollock as a prey source.
Postpartum whistle production in bottlenose dolphins
Authors: Fripp Deborah , Tyack Peter
Published: May 2008

Abstract

Despite much research on bottlenose dolphin signature whistles, few have investigated the role of maternal whistles in early calf development. We investigated maternal whistle use in the first weeks postpartum for captive dolphins. The overall whistling rate increased by a factor of ten when the calves were born and then decreased again in the third week of the one surviving calf. Adult whistles were distinguished from calf whistles based on the extent of frequency modulation and were further classified into signature and non‐signature whistles by comparison to a dictionary of known whistles. The average rate of maternal signature whistle production increased significantly from 0.02 whistles per dolphin‐minute before the calves were born to 0.2 and 0.3 whistles in weeks 1 and 2, decreasing again to 0.06 in week 3 for the mother of the surviving calf. Percent maternal signature whistles changed similarly. Signature whistle production by non‐mothers did not change when the calves were born. A likely function of this increase in maternal signature whistle production is that it enables the calf to learn to identify the mother in the first weeks of life.
Trophic level and overlap of sea lions (Zalophus californianus) in the Gulf of California, Mexico
Authors: Porras‐Peters Heidi , Aurioles‐Gamboa David , Cruz‐Escalona Victor Hugo , Koch Paul L.
Published: May 2008

Abstract

Stable isotope and scat analyses were used in concert to determine trophic level and dietary overlap among California sea lions from different rookeries in the Gulf of California. Isotopic analysis of the fur of sea lion pups revealed differences in δ15N and δ13C values among rookeries during the breeding season. Mean δ15N and δ13C values varied from 20.2‰ to 22.4‰ and from −15.4‰ to −14.0‰, respectively. The pattern of differences among rookeries was similar between years in most cases. Isotopic variations among rookeries were associated with differences in prey consumption. There was a significant correlation between δ15N value and trophic level, as determined by scat analysis. Joint application of isotopic and scat analyses allowed us to identify how the feeding habits of sea lions vary with location. Our results suggest the presence of spatial structure in available prey as well as the localized use of prey by sea lions across the Gulf of California.
Aspects of behavioral ecology of Sotalia guianensis in Sepetiba Bay, southeast Brazil
Authors: Flach Leonardo , Flach Patricia A. , Chiarello Adriano G.
Published: May 2008

Abstract

Boat‐based surveys were conducted from August 2002 to July 2003 to study the activity patterns, spatial pattern of area use, and group characteristics of Sotalia guianensis in Sepetiba Bay, southeast Brazil. Predetermined routes covered the entrance and interior of the bay, resulting in 210 dolphin sightings during 3,300 km total effort. Data on activity were collected using scan group sampling with instantaneous recording after 5 min of observation. Dolphins were sighted more frequently in the entrance of the bay, where water is deeper, and salinity and transparency are higher, than in the interior of the bay, where the environment is more influenced by freshwater inputs. Foraging and feeding were the most frequent activities, and occurred predominantly between 0600 and 1000. Foraging and feeding peaked during ebbing, low, and flooding tides, while socializing predominated at high tide. Mean group size was larger in the interior of the bay and when seabirds were present. Large aggregations containing >100 individuals of Sotalia guianensis seen year‐round indicate that Sepetiba Bay is an important area for this species in coastal Brazil.
Adaptation to ER stress as a driver of malignancy and resistance to therapy in human melanoma
Authors: Hersey Peter , Zhang Xu Dong
Published: May 2008

Primary events in the development of melanoma are gradually being pieced together but a more complete picture of evolution of the disease requires additional understanding of secondary events consequent on initiation of the malignancy. Arguably, the most important driver of secondary events is signals resulting from induction of endoplasmic reticulum (ER) stress for example due to hypoglycaemia and anoxia. This may result in a variety of responses such as apoptosis, autophagy and senescence depending on the initiating event and cell type but most importantly it may result in progression of melanoma due to adaptation and selection of melanoma cells to ER stress. The following reviews what is known about the adaptive responses and how this information may provide new initiatives in treatment of the disease.
Effectiveness of marine reserve networks in representing biodiversity and minimizing impact to fishermen: a comparison of two approaches used in California
Authors: Klein Carissa Joy , Steinback Charles , Scholz Astrid J. , Possingham Hugh P.
Published: May 2008

We compared the effectiveness of marine reserve networks designed using a numerical optimization tool with networks designed by stakeholders during the course of California's Marine Life Protection Act Initiative at representing biodiversity and minimizing estimated negative impacts to fishermen. We used the same spatial data representing biodiversity and recreational fishing effort that were used by the stakeholders to design marine reserves. In addition, we used commercial fishing data not explicitly available to the stakeholders. Networks of marine reserves designed with numerical optimization tools represented the same amount of each habitat, or more, and had less of an estimated impact on commercial and recreational fisheries than networks designed by the stakeholders. The networks designed by the stakeholders could have represented 2.0–9.5% more of each habitat with no additional impact on the fisheries. Of four different marine reserve proposals considered in the initiative, the proposal designed by fishermen was more efficient than the proposals designed by other stakeholder groups at representing biodiversity and minimizing impact to the fishing industry. These results highlight the necessity of using comprehensive information on fishing effort to design a reserve network that efficiently minimizes negative socioeconomic impacts. We recommend that numerical optimization tools support, not replace, the stakeholder‐driven reserve design process along California's northern and southern coasts to help accomplish two of the initiative's core objectives: (1) Protect representative and unique marine habitats, and (2) Minimize negative socioeconomic impacts. The involvement of stakeholders is necessary as additional factors important to reserve design can not be considered using a numerical optimization tool.
Preferential motor unit loss in the SOD1G93A transgenic mouse model of amyotrophic lateral sclerosis
Authors: Hegedus J. , Putman C. T. , Tyreman N. , Gordon T.
Published: May 2008

The present study investigated motor unit (MU) loss in a murine model of familial amyotrophic lateral sclerosis (ALS). The fast‐twitch tibialis anterior (TA) and medial gastrocnemius (MG) muscles of transgenic SOD1G93A and SOD1WT mice were studied during the presymptomatic phase of disease progression at 60 days of age. Whole muscle maximum isometric twitch and tetanic forces were 80% lower (P < 0.01) in the TA muscles of SOD1G93A compared to SOD1WT mice. Enumeration of total MU numbers within TA muscles showed a 60% reduction (P < 0.01) within SOD1G93A mice (38 ± 7) compared with SOD1WT controls (95 ± 12); this was attributed to a lower proportion of the most forceful fast‐fatigable (FF) MU in SOD1G93A mice, as seen by a significant (P < 0.01) leftward shift in the cumulative frequency histogram of single MU forces. Similar patterns of MU loss and corresponding decreases in isometric twitch force were observed in the MG. Immunocytochemical analyses of the entire cross‐sectional area (CSA) of serial sections of TA muscles stained with anti‐neural cell adhesion molecule (NCAM) and various monoclonal antibodies for myosin heavy chain (MHC) isoforms showed respective 65% (P < 0.01) and 28% (P < 0.05) decreases in the number of innervated IIB and IID/X muscle fibres in SOD1G93A, which paralleled the 60% decrease (P < 0.01) in the force generating capacity of individual fibres. The loss of fast MUs was partially compensated by activity‐dependent fast‐to‐slower fibre type transitions, as determined by increases (P < 0.04) in the CSA and proportion of IIA fibres (from 4% to 14%) and IID/X fibres (from 31% to 39%), and decreases (P < 0.001) in the CSA and proportion of type IIB fibres (from 65% to 44%). We conclude that preferential loss of IIB fibres is incomplete at 60 days of age, and is consistent with a selective albeit gradual loss of FF MUs that is not fully compensated by sprouting of the remaining motoneurons that innervate type IIA or IID/X muscle fibres. Our findings indicate that disease progression in fast‐twitch muscles of SOD1G93A mice involves parallel processes: (1) gradual selective motor axon die‐back of the FF motor units that contain large type IIB muscle fibres, and of fatigue‐intermediate motor units that innervate type IID/X muscle fibres, and (2) activity‐dependent conversion of motor units to those innervated by smaller motor axons innervating type IIA fatigue‐resistant muscle fibres.
Offspring from mothers fed a ‘junk food’ diet in pregnancy and lactation exhibit exacerbated adiposity that is more pronounced in females
Authors: Bayol S. A. , Simbi B. H. , Bertrand J. A. , Stickland N. C.
Published: May 2008

We have shown previously that a maternal junk food diet during pregnancy and lactation plays a role in predisposing offspring to obesity. Here we show that rat offspring born to mothers fed the same junk food diet rich in fat, sugar and salt develop exacerbated adiposity accompanied by raised circulating glucose, insulin, triglyceride and/or cholesterol by the end of adolescence (10 weeks postpartum) compared with offspring also given free access to junk food from weaning but whose mothers were exclusively fed a balanced chow diet in pregnancy and lactation. Results also showed that offspring from mothers fed the junk food diet in pregnancy and lactation, and which were then switched to a balanced chow diet from weaning, exhibited increased perirenal fat pad mass relative to body weight and adipocyte hypertrophy compared with offspring which were never exposed to the junk food diet. This study shows that the increased adiposity was more enhanced in female than male offspring and gene expression analyses showed raised insulin‐like growth factor‐1 (IGF‐1), insulin receptor substrate (IRS)‐1, vascular endothelial growth factor (VEGF)‐A, peroxisome proliferator‐activated receptor‐γ (PPARγ), leptin, adiponectin, adipsin, lipoprotein lipase (LPL), Glut 1, Glut 3, but not Glut 4 mRNA expression in females fed the junk food diet throughout the study compared with females never given access to junk food. Changes in gene expression were not as marked in male offspring with only IRS‐1, VEGF‐A, Glut 4 and LPL being up‐regulated in those fed the junk food diet throughout the study compared with males never given access to junk food. This study therefore shows that a maternal junk food diet promotes adiposity in offspring and the earlier onset of hyperglycemia, hyperinsulinemia and/or hyperlipidemia. Male and female offspring also display a different metabolic, cellular and molecular response to junk‐food‐diet‐induced adiposity.
Control of neuroblast production and migration by converging GABA and glutamate signals in the postnatal forebrain
Authors: Platel Jean‐Claude , Dave Kathleen A. , Bordey Angélique
Published: May 2008

The production of adult‐born neurons is an ongoing process accounting for > 10 000 immature neurons migrating to the olfactory bulb every day. This high turnover rate necessitates profound control mechanisms converging onto neural stem cells and neuroblasts to achieve adequate adult‐born neuron production. Here, we elaborate on a novel epigenetic control of adult neurogenesis via highly coordinated, non‐synaptic, intercellular signalling. This communication engages the neurotransmitters GABA and glutamate, whose extracellular concentrations depend on neuroblast number and high affinity uptake systems in stem cells. Previous studies show that neuroblasts release GABA providing a negative feedback control of stem cell proliferation. Recent findings show an unexpected mosaic expression of glutamate receptors leading to calcium elevations in migrating neuroblasts. We speculate that stem cells release glutamate that activates glutamate receptors on migrating neuroblasts providing them with migratory and survival cues. In addition, we propose that the timing of neurotransmitter release and their spatial diffusion will determine the convergent coactivation of neuroblasts and stem cells, and provide a steady‐state level of neuroblast production. Upon external impact or injury this signalling may adjust to a new steady‐state level, thus providing non‐synaptic scaling of neuroblast production.
Dynamic Motion Planning of 3D Human Locomotion Using Gradient-Based Optimization
Authors: Kim Hyung Joo , Wang Qian , Rahmatalla Salam , Swan Colby C. , Arora Jasbir S. , Abdel-Malek Karim , Assouline Jose G.
Published: May 2008

Since humans can walk with an infinite variety of postures and limb movements, there is no unique solution to the modeling problem to predict human gait motions. Accordingly, we test herein the hypothesis that the redundancy of human walking mechanisms makes solving for human joint profiles and force time histories an indeterminate problem best solved by inverse dynamics and optimization methods. A new optimization-based human-modeling framework is thus described for predicting three-dimensional human gait motions on level and inclined planes. The basic unknowns in the framework are the joint motion time histories of a 25-degree-of-freedom human model and its six global degrees of freedom. The joint motion histories are calculated by minimizing an objective function such as deviation of the trunk from upright posture that relates to the human model’s performance. A variety of important constraints are imposed on the optimization problem, including (1) satisfaction of dynamic equilibrium equations by requiring the model’s zero moment point (ZMP) to lie within the instantaneous geometrical base of support, (2) foot collision avoidance, (3) limits on ground-foot friction, and (4) vanishing yawing moment. Analytical forms of objective and constraint functions are presented and discussed for the proposed human-modeling framework in which the resulting optimization problems are solved using gradient-based mathematical programing techniques. When the framework is applied to the modeling of bipedal locomotion on level and inclined planes, acyclic human walking motions that are smooth and realistic as opposed to less natural robotic motions are obtained. The aspects of the modeling framework requiring further investigation and refinement, as well as potential applications of the framework in biomechanics, are discussed.
The Influence of Test Conditions on Characterization of the Mechanical Properties of Brain Tissue
Authors: Hrapko M. , van Dommelen J. A. W. , Peters G. W. M. , Wismans J. S. H. M.
Published: May 2008

To understand brain injuries better, the mechanical properties of brain tissue have been studied for 50years; however, no universally accepted data set exists. The variation in material properties reported may be caused by differences in testing methods and protocols used. An overview of studies on the mechanical properties of brain tissue is given, focusing on testing methods. Moreover, the influence of important test conditions, such as temperature, anisotropy, and precompression was experimentally determined for shear deformation. The results measured at room temperature show a stiffer response than those measured at body temperature. By applying the time-temperature superposition, a horizontal shift factor aT=8.5–11 was found, which is in agreement with the values found in literature. Anisotropy of samples from the corona radiata was investigated by measuring the shear resistance for different directions in the sagittal, the coronal, and the transverse plane. The results measured in the coronal and the transverse plane were 1.3 and 1.25 times stiffer than the results obtained from the sagittal plane. The variation caused by anisotropy within the same plane of individual samples was found to range from 25% to 54%. The effect of precompression on shear results was investigated and was found to stiffen the sample response. Combinations of these and other factors (postmortem time, donor age, donor type, etc.) lead to large differences among different studies, depending on the different test conditions.
Lumped Parameter Thermal Model for the Study of Vascular Reactivity in the Fingertip
Authors: Ley O. , Deshpande C. , Prapamcham B. , Naghavi M.
Published: May 2008

Vascular reactivity (VR) denotes changes in volumetric blood flow in response to arterial occlusion. Current techniques to study VR rely on monitoring blood flow parameters and serve to predict the risk of future cardiovascular complications. Because tissue temperature is directly impacted by blood flow, a simplified thermal model was developed to study the alterations in fingertip temperature during arterial occlusion and subsequent reperfusion (hyperemia). This work shows that fingertip temperature variation during VR test can be used as a cost-effective alternative to blood perfusion monitoring. The model developed introduces a function to approximate the temporal alterations in blood volume during VR tests. Parametric studies are performed to analyze the effects of blood perfusion alterations, as well as any environmental contribution to fingertip temperature. Experiments were performed on eight healthy volunteers to study the thermal effect of 3min of arterial occlusion and subsequent reperfusion (hyperemia). Fingertip temperature and heat flux were measured at the occluded and control fingers, and the finger blood perfusion was determined using venous occlusion plethysmography (VOP). The model was able to phenomenologically reproduce the experimental measurements. Significant variability was observed in the starting fingertip temperature and heat flux measurements among subjects. Difficulty in achieving thermal equilibration was observed, which indicates the important effect of initial temperature and thermal trend (i.e., vasoconstriction, vasodilatation, and oscillations).
The motion of a freely falling chain tip: Force measurements
Authors: Géminard Jean-Christophe , Vanel Loïc
Published: May 2008

A chain is firmly attached at one end while the other falls freely in the gravitational field. We report careful time-resolved measurements of the horizontal and vertical components of the force applied by the chain on the mount. Our results complement previous laboratory measurements and simulations of the free end dynamics.
Sparsity constrained deconvolution approaches for acoustic source mapping
Authors: Yardibi Tarik , Li Jian , Stoica Petre , Cattafesta Louis N.
Published: May 2008

Using microphone arrays for estimating source locations and strengths has become common practice in aeroacoustic applications. The classical delay-and-sum approach suffers from low resolution and high sidelobes and the resulting beamforming maps are difficult to interpret. The deconvolution approach for the mapping of acoustic sources (DAMAS) deconvolution algorithm recovers the actual source levels from the contaminated delay-and-sum results by defining an inverse problem that can be represented as a linear system of equations. In this paper, the deconvolution problem is carried onto the sparse signal representation area and a sparsity constrained deconvolution approach (SC-DAMAS) is presented for solving the DAMAS inverse problem. A sparsity preserving covariance matrix fitting approach (CMF) is also presented to overcome the drawbacks of the DAMAS inverse problem. The proposed algorithms are convex optimization problems. Our simulations show that CMF and SC-DAMAS outperform DAMAS and as the noise in the measurements increases, CMF works better than both DAMAS and SC-DAMAS. It is observed that the proposed algorithms converge faster than DAMAS. A modification to SC-DAMAS is also provided which makes it significantly faster than DAMAS and CMF. For the correlated source case, the CMF-C algorithm is proposed and compared with DAMAS-C. Improvements in performance are obtained similar to the uncorrelated case.
Comparison of spheroidal and eigenfunction-expansion trial functions for a membrane in an infinite baffle
Authors: Mellow Tim , Kärkkäinen Leo
Published: May 2008

The on-axis far-field pressure response of a circular membrane in an infinite baffle when driven by a uniformly distributed electrostatic force is calculated using two different trial functions for the surface velocity distribution. The first is an expansion based upon a solution to the free space wave equation in oblate spheroidal coordinates, which has already been derived in a previous paper [J. Acoust. Soc. Am. 120(5), 2460–2477 (2006)], and the second is a membrane eigenfunction expansion (or Bessel series), which is rigorously derived in this letter. Although the latter can be used as a basis for calculating a number of different radiation characteristics such as the radiation impedance or directivity, etc., only the on-axis far-field sound pressure is considered here. The results are compared and discussed.
Relative weights for frequency glide detection using narrowband noise
Authors: Qian Jinyu , Richards Virginia M.
Published: May 2008

Narrowband noise stimuli were used to derive relative weights for detecting frequency glides in a yes/no procedure. One stimulus set was restricted to the duration of the glide. For the second stimulus set, there were fringe noise bands preceding and following the glide. For both sets, the center frequency of the linear glide was either fixed at 1000Hz or randomly chosen on each trial from the range of 800–1200Hz. Relative weights as a function of time were derived using a linear model and the linear classification method [A. Ahumada, J. Vis., 2, 121–131 (2002)]. Sensitivity was better for the fixed- than random-frequency conditions, and weight patterns from the random-frequency conditions were less reliable than those obtained from the fixed-frequency conditions. The magnitudes of the relative weights tended to be larger for the second half of the stimulus, suggesting that subjects paid more attention to the later than the earlier parts of stimuli. In the random-frequency conditions, the linear model failed to account for subjects’ performance unless the stimuli were expressed in terms of relative changes in frequency rather than absolute frequency.
Shape-based ultrasound tomography using a Born model with application to high intensity focused ultrasound therapy
Authors: Ülker Karbeyaz Başak , Miller Eric L. , Cleveland Robin O.
Published: May 2008

A shaped-based ultrasound tomography method is proposed to reconstruct ellipsoidal objects using a linearized scattering model. The method is motivated by the desire to detect the presence of lesions created by high intensity focused ultrasound (HIFU) in applications of cancer therapy. The computational size and limited view nature of the relevant three-dimensional inverse problem renders impractical the use of traditional pixel-based reconstruction methods. However, by employing a shape-based parametrization it is only necessary to estimate a small number of unknowns describing the geometry of the lesion, in this paper assumed to be ellipsoidal. The details of the shape-based nonlinear inversion method are provided. Results obtained from a commercial ultrasound scanner and a tissue phantom containing a HIFU-like lesion demonstrate the feasibility of the approach where a 20mm×5mm×6mm ellipsoidal inclusion was detected with an accuracy of around 5%.
Perception and cortical neural coding of harmonic fusion in ferrets
Authors: Kalluri Sridhar , Depireux Didier A. , Shamma Shihab A.
Published: May 2008

This study examined the perception and cortical representation of harmonic complex tones, from the perspective of the spectral fusion evoked by such sounds. Experiment 1 tested whether ferrets spontaneously distinguish harmonic from inharmonic tones. In baseline sessions, ferrets detected a pure tone terminating a sequence of inharmonic tones. After they reached proficiency, a small fraction of the inharmonic tones were replaced with harmonic tones. Some of the animals confused the harmonic tones with the pure tones at twice the false-alarm rate. Experiment 2 sought correlates of harmonic fusion in single neurons of primary auditory cortex and anterior auditory field, by comparing responses to harmonic tones with those to inharmonic tones in the awake alert ferret. The effects of spectro-temporal filtering were accounted for by using the measured spectrotemporal receptive field to predict responses and by seeking correlates of fusion in the predictability of responses. Only 12% of units sampled distinguished harmonic tones from inharmonic tones, a small percentage that is consistent with the relatively weak ability of the ferrets to spontaneously discriminate harmonic tones from inharmonic tones in Experiment 1.
Acoustics and sustainable design in exposed structures
Authors: Roy Kenneth P. , Snader Anita L.
Published: May 2008

Two very important emerging architectural trends in the USA are to 1) 'open up' the space design as exposed structures, and 2) incorporate sustainable design into building interiors. We as acoustic designers would like to know the consequences of both on acoustics performance and occupant satisfaction and work performance. The first concern is addressed in a study by CISCA evaluating the effects of ceiling plenum vs. exposed structures in both office and retail spaces. And the second issue of compatibility of sustainable design objectives with acoustic performance is addressed by a pertinent field survey by the Center for the Built Environment (CBE at Univ. of CA, Berkeley) on occupant satisfaction and performance. The issue of the availability and use of 'green' acoustic building materials that not only meet sustainability and energy goals, but also serve to ensure that our buildings actually work for their intended purposes will be addressed. Finally, the increased awareness of the acoustic impact of 'green' design on occupant satisfaction is being seen in the evolution of LEED and other 'green' rating systems.
Echo suppression effect and coloration of periodic-type diffusers
Authors: Toyoda Masahiro , Furukawa Tomohiro , Takahashi Daiji
Published: May 2008

Walls and ceilings are often designed to suppress undesirable echoes. For that purpose, walls and ceilings are given absorptive surfaces which absorb sound energy or uneven surfaces which provide wave diffusion. While it is not difficult to predict the degree of echo suppression effects in the case of absorptive surfaces, it is generally difficult to do that in the case of uneven surfaces. In addition, if the surfaces have periodicity, unintended effects called coloration can distort tonal characteristics of the sound field. Thus, many acoustic designers would hesitate to employ this kind of periodic-type diffusers. However, there are some cases where it is necessary to suppress echoes without any energy loss. Periodic-type diffusers have the advantages of easy estimation of diffusion properties, simple method of design, and ready availability. In this study, a subjective experiment with simulated stimuli was carried out to clarify the echo suppression effect of the periodic-type diffusers from the viewpoint of reflected energy level. Although coloration interfered in subjective judgments in some cases of the experiment, it is shown that the periodic-type diffusers have echo suppression effect if coloration does not occur. This study is also devoted to discussion about the cause of the coloration.
Acoustical design of Shenzhen Concert Hall, Shenzhen China
Authors: Oguchi Keiji , Toyota Yasuhisa
Published: May 2008

The Shenzhen Concert Hall complex opened in Shenzhen, China on October 12, 2007. The complex contains the Symphony Hall with 1,800 audience seats, the Theater Studio with 400 - 580 seats and some rooms for rehearsing. The Symphony Hall has a vineyard configuration with a steep audience block arrangement, called "canyon terrace". At the widest point of the audience seating, the room spans 45m, is 60m long and has a ceiling height of 25 m. The polycarbonate ensemble reflector panels are suspended at the height of approx.15m above the stage. The acoustical design and characteristics of the Concert Hall are reported.
Dynamic sound image creation by un-directional sound beam reproduction toward an interior surface with a DSP controlled line array speaker for Surround Sound Composition
Authors: Shimizu Yasushi , Hata Masato , Ito Atsuko , Miki Akira , Hatanaka Masato
Published: May 2008

Surround Sound Composition in an indoor space is frequently provided with spatial sounds, giving both a sound localization and surround sound effect. Systems have been installed in public spaces such as a museum and retail shops. However, technical improvements are required to provide a small sweet spot and to address architectural designs for speaker installation, because multiple speakers are required for surround sound effect. Recently, we have been applying DSP beam-forming technology with a line-array speaker to create a 3D sound image by scanning a focused sound beam onto an interior surface. The DSP array speaker is capable of providing static and dynamic control in beam steering and sound focusing. Therefore, dynamic spatial sound effect on the interior surface is possible, wherein un-directional sound reproduction is analogous to un-directional lighting. We present three case studies; 1) Virtual 3D Surround Sound in multi-media improvisation, 2) 3D Spatial Sound Synthesis in sound installation and 3) Sound Installation with a Dynamic Sound Beam Scanning.
Overview of low frequency control options in rooms
Authors: D'Antonio Peter
Published: May 2008

Low frequency control of modes and speaker boundary interference in rooms has been a persistent problem that affects the sound field in rooms. However, many innovative techniques have been developed to address these problems. This presentation will be an overview of approaches that address the optimization of room dimensions to provide the flattest room response and speaker/listener placement to minimize speaker-boundary interference; the mechanism and design of passive absorption devices based on Helmholtz resonators, diaphragmatic limp mass membranes, plate resonators and microperforated panels will be described and characterized; as well as electro-acoustic approaches, using equalization, active absorbers and the optimal placement of multiple in-phase subwoofers.
An improved low frequency radiation model for finite sound reflectors
Authors: Rathsam Jonathan , Wang Lily M. , Rindel Jens Holger , Christensen Claus Lynge
Published: May 2008

Geometric computer models for room acoustics, such as ODEON, predict sound fields most reliably at high frequencies. At low frequencies, algorithms must be modified to account for deviations from geometrical acoustics caused by wave phenomena. For finite reflectors, a common low frequency model is based on the Kirchhoff-Fresnel Diffraction Approximation, which predicts a uniform 6 dB per octave slope below a reflector's geometrical limiting frequency. As discussed in this paper, highly accurate Boundary Element Method simulations, not subject to the Kirchhoff Approximation, suggest the use of an additional, lower limiting frequency and slope of 12 dB per octave to represent the reflector's response at the lowest frequencies. This second limiting frequency and 12 dB per octave slope, referred to as the dipole limiting frequency, are presented in a form suitable for insertion into a geometric computer model. [Work supported by the National Science Foundation.]
A simple acoustical exposure metric based on biological thresholds and integrating a temporal characteristics exposure axis
Authors: Stocker Michael , Reuterdahl Tom , Horn Libbie , Hurley Gail
Published: May 2008

Anthropogenic noise is compromising habitat for marine mammals, fish and potentially other marine organisms. Determining acceptable exposure thresholds is confounded by the fact that marine animals have adapted to some exceedingly loud naturally occurring sounds, while exposure to certain anthropogenic noises at equivalent or lower amplitudes causes harm. It is clear that mitigation levels can not be established by signal amplitude alone and that other signal characteristics are significant factors in biological responses to noise exposure. This proposed metric continues ongoing work on a simple exposure metric based on broadband frequency and amplitude representation of a subject noise with the time domain represented in the Z axis.
Acoustic communication and navigation in the Arctic Ocean
Authors: Baggeroer Arthur B. , Freitag Lee , Priesig James E. , Nagle Daniel
Published: May 2008

Acoustic communication and navigation in the Arctic usually implies surface interaction because of the upward refracting profile. While open water leeds and polyna exist, sensors must also be deployed beneath the ice. Nominal roughness of several meters plus ubiquitous ice keels all lead to complicated multipath propagation typically of durations from 0.1 to 10 seconds. Pack ice drifts at scales of 0.1-0.2 nm/s leading to doppler shifts/spreads of 2 - 8 Hz at 10-20 kHz carriers. These lead to highly spread channels with lots of ISI. Wise signal and code designs coupled with equalizers are critical to successful performance of acomms system even at low rates. Navigation such as by long base line systems encounter the same multipath. Path detectors and trackers are easily confused in determining interactions with the underside of the ice cover. Often, first arrivals are weak and do not trigger detectors. This leads to "lane" skipping by tracking algorthms and sychonization errors for acomms. This implies clever "track association" algorithms to identify the arrival patterns and then transform them to locations which move with ice drift. This presentation outlines acoustic problems which communicaton and navigation systems must overcome using data take from several Arctic experiments.
Sound fixing and ranging beneath sea-ice
Authors: Gascard Jean-Claude
Published: May 2008

Sound fixing and ranging techniques, the so-called SOFAR technique, is widely used in the field of oceanography for tracking neutrally buoyant floats underwater over large distances (several thousands of kilometres) and for long periods of time (several years). The range propagation depends largely on the existence or not of the SOFAR sound channel. Twenty years ago we investigated SOFAR acoustic propagation under sea-ice over large distances and at various frequencies from 80 Hz up to 1560 Hz. We discovered the range for acoustic propagation was much reduced (100 kms to 150 kms) no matter the frequency used. This was due to large scattering induced by under sea-ice topography since there is no way to avoid acoustic rays to bounce back to the surface towards sea-ice and create multiple reflections. More recently during the Tara Damocles transpolar drift across the Arctic Ocean, we reinvestigated the SOFAR acoustic range propagation under sea-ice for longer periods of time in various conditions (summer and winter conditions). Our results confirmed those obtained 20 years ago and indicated a high sensitivity to the ambient conditions. We are presenting the results obtained during the late fall- early winter months of the Tara transpolar drift across the Arctic Ocean.
Ecosystem acoustics: meeting management needs
Authors: Godoe Olav Rune
Published: May 2008

Marine ecosystems and their exploited resources are often monitored through quasi-synoptic scientific surveys that produce estimates of population characteristics at periodic intervals. Spatial and temporal variability is an integral part of ecosystem function but is often ignored in traditional assessment methodology due to the inability of conventional surveys to resolve and quantify such effects. This confounds estimates of the state of the ecosystem and its main populations and obscures understanding of its dynamics and function. The concept and approach of ecosystem acoustics, which are elaborated and illustrated in this presentation, exploit both active and passive acoustics over their full bandwidth from a range of platforms giving temporal and spatial resolution sufficient for assessing the state of ecosystems including their main component organisms. Application of new platforms and sensors, as well as combinations of these, is enhancing the power of the approach. Ecosystem acoustics enables observations of marine life to be made on spatial and temporal scales relevant to understanding ecosystem function and assessment of system dynamics and state.