bluuebunny/crossref_metadata_2025 huggingface dataset:
Non-neotenous origin of the palaeognathous (Aves) pterygoidpalate complex
Authors: Gussekloo S W.S , Bout R G
Published: November 2002

Recent studies on the phylogeny of modern birds have indicated that the Palaeognathae may not be the most basal group in modern birds, but are derived within the group. This resulted in the revival of the theory that the Palaeognathae have evolved through neoteny from a flying ancestor. Neoteny was also suggested by other authors after finding palaeognath-like characters in neognathous birds after experimentally induced neoteny (neonatal thyroidectomy). In this study, we test whether the most important palaeognathous character, the palaeognathous pterygoidpalate complex (PPC), has indeed evolved through neoteny. We used a numerical method to compare the morphology of the PPC of adult palaeognathous species with the PPC of several stages of development of a neognathous species. The results show that the morphology of the palaeognathous PPC is, in general, very different from ontogenetic stages of the neognathous species, indicating a non-neotenous origin of the palaeognathous PPC.
Intra-hair stable isotope analysis implies seasonal shift to salmon in gray wolf diet
Authors: Darimont C T , Reimchen T E
Published: November 2002

Seasonal shifts in diet are widespread, but our ability to detect them can be limited. Comparisons of stable isotope signatures in metabolically inert tissue portions grown at different times are inadequately exploited in dietary reconstructions. We propose that segments of guard hair can index diet to periods of growth (i.e., seasons differing in resource availability). We examined inter-hair δ13C and δ15N signatures from gray wolves (Canis lupus) of British Columbia to test whether the bulk of enriched (marine-derived) nutrients was assimilated during fall, the peak of salmon (Onchorynchus spp.) migration. In five animals, we detected a seasonal dietary shift: relatively more13C and15N was assimilated during fall than during summer, suggesting use of salmon during fall. Twelve wolves and both controls showed no seasonal shift in diet. Using salmon when available may be adaptive, given its predictability, spatial constraint, caloric content, and lower potential to inflict injury relative to that imposed by large mammals. Our study complements others that also used novel and fine-scale isotope approaches and may permit the identification of otherwise undetectable niche differentiation among conspecifics or heterospecifics.
Dive shapes reveal temporal changes in the foraging behaviour of different age and sex classes of harbour seals (Phoca vitulina)
Authors: Baechler J , Beck C A , Bowen W D
Published: November 2002

Classifying dives into two-dimensional shapes based on time and depth is an attempt to extract additional information about the behaviour of aquatic air-breathing predators. In some species, there is considerable circumstantial evidence that different dive shapes represent different behaviours. However, few studies have provided direct evidence of the relationship between dive shape and function. We classified over 283 000 dives of adults (31 males and 45 females) and suckling (13) and recently weaned (15) harbour seal (Phoca vitulina) pups into seven shapes using supervised discriminant function analysis. Changes in the percentage of U-shaped dives over time within adults and weaned pups were associated with changes in food intake derived from water-flux studies on subsets of the same individuals. The changes in the percentage of U-shaped dives were accompanied by roughly reciprocal changes in V-shaped dives, whereas there was little change in other dive shapes, indicating that V-shaped dives are not generally exhibited during foraging. Video of adult males (from an animal-borne video system) also showed that there was a strong but not exclusive association between foraging and U-shaped dives. Our results indicate that changes in the percentage of U-shaped dives may serve as a reasonable index of changes in foraging behaviour. However, behaviours of suckling pups and adult males during the breeding season cannot be easily inferred from dive shape alone.
Effect of larval body size on overwinter survival and emerging adult size in the burying beetle, Nicrophorus investigator
Authors: Smith Rosemary J
Published: November 2002

Body size may influence both adult fecundity and the probability of survival through each life stage. Previous studies of burying beetles (Nicrophorus, Coleoptera: Silphidae) have revealed reproductive advantages for larger adults and the role of parental care in determining larval size and number. In this study I measure the effect of size on survival over the winter period and the correlation between larval size and the size of emerging adults. I collected data from 24 groups of 2025 larvae sorted by size and overwintered outside under natural conditions in Colorado, U.S.A. There was a significant positive correlation between larval size and adult size at emergence and a significant effect of size on overwinter survival. Data from 2 years yielded the following mean survival rates: small, 47.3 ± 1.0%; medium, 73.2 ± 0.7%; large, 85.7 ± 0.4%. These values were then used to accurately predict adult emergence from broods of larvae whose range of size was measured prior to the overwinter period. The results indicate that selection for large body size may result from an overwinter survival advantage and not just from reproductive success. This has implications for fitness models of parental care and models of population dynamics.
Vitamin A physiology in the precocious harbour seal (Phoca vitulina): a tissue-based biomarker approach
Authors: Mos Lizzy , Ross Peter S
Published: November 2002

Vitamin A is a nutrient essential to all mammals for growth and development, as well as for the maintenance of reproductive, endocrine, and immune systems. Environmental contaminant-related disruption of vitamin A has been observed in many wildlife species and can therefore be used as a biomarker of toxic effects. However, the natural processes regulating vitamin A uptake, storage, and distribution among compartments are poorly understood in marine mammals. In this study, 20 young healthy harbour seals (Phoca vitulina) were captured to establish a compartment-based model providing a foundation for a mechanistic understanding of vitamin A physiology and disruption. Vitamin A (retinol, retinyl palmitate, and (or) retinoic acid) was quantified in blood plasma and in biopsy samples of liver, blubber, and skin. Although the highest concentrations of vitamin A were found in liver, blubber represents a more important storage depot, with an estimated 66% of the total retinoid content of the compartments measured. We suggest that vitamin A physiology in the precocious harbour seal has evolved to deal with high vitamin A availability during a short nursing period and to sustain growth during the postweaning fast. Positive correlations in vitamin A concentrations among liver, blubber, and skin support the use of less invasive biopsy sampling of just blubber or skin, which can provide physiologically relevant information in biomarker studies of free-ranging marine mammals.
Beating the odds: effects of weather on a short-season population of deer mice
Authors: Kalcounis-Rueppell Matina C , Millar John S , Herdman Emily J
Published: November 2002

We examined 11 years of data on reproductive success, survival, and population dynamics of two populations (Fortress and Grizzly) of deer mice (Peromyscus maniculatus) in the Kananaskis Valley, Alberta, to investigate the extent to which the dynamics of these populations is dictated by weather conditions. Summer population growth was not related to the population growth in the winter preceding the breeding season or to spring population density. Over the summer on the Fortress grid, population growth was positively related to adult survival, whereas on the Grizzly grid, population growth was positively related to nestling survival. Neither summer population growth nor demographic correlates of summer population growth was consistently related to weather patterns. On Fortress, adult survival during the breeding season was negatively correlated with precipitation. On Grizzly, nestling survival during the breeding season was negatively correlated with precipitation. Winter population growth was inversely proportional to the fall population density prior to the winter but neither was related to weather conditions. Climate limits seasonal breeding in these populations, but compensatory responses appear sufficient to accommodate extreme weather conditions during both the breeding and nonbreeding seasons.
Individual and seasonal differences in antipredatory behaviour of root volesa field experiment
Authors: Borowski Zbigniew
Published: November 2002

The response of root vole (Microtus oeconomus) to least weasel (Mustela nivalis) odours during breeding (August) and nonbreeding seasons (November) was studied in the root voles' natural habitat. The aim of this study was to determine if antipredator behaviour of the root vole changed between breeding and nonbreeding seasons and if this change was closely related to individual environmental cues, e.g., weasel odours. It was found that when bait and weasel odour was used, trappability was greater in breeding season than in nonbreeding season. Moreover, in the breeding season, heavier (i.e., older) voles were more frequently captured than lighter (i.e., younger) ones. Results show that voles' antipredator behaviour of weasel avoidance changes seasonally and that during the breeding season voles display a trade-off conflict between predator risk and foraging, if predator risk is high. It is possible that older voles are driven to reproduce in the current breeding season and thus display less weasel avoidance than do younger voles, which have higher probability of surviving to the next breeding season. Results indicate that indirect (nonlethal) effects of mammalian predators on voles' behaviour strongly depend on age, sexual activity, and season.
Den trees used by northern flying squirrels (Glaucomys sabrinus) in southeastern Alaska
Authors: Bakker V J , Hastings K
Published: November 2002

Northern flying squirrel (Glaucomys sabrinus) dens are reportedly associated with features characteristic of older forests, and den availability is a potential limiting factor in younger forests. We assessed den sites used by northern flying squirrels in southeastern Alaska, where we expected den-site selection to differ from more southerly forests, owing to increased thermal stress but reduced predation and competition. We located 27 squirrels in 76 dens and compared den trees with 1875 matched random trees. Most dens ([Formula: see text]73%) were in cavities and 21% were at heights of [Formula: see text]3 m. This high rate of cavity use, including cavities low in the bole, likely reflects the importance of weatherproof dens in this cool wet region. Northern flying squirrels preferentially used trees with indicators of cavity presence, selecting for snags and for larger diameter trees with bole entries, conks, abundant mistletoe, and dead tops. Although cavity availability is probably not limiting populations in this region currently, cavity-supporting trees would be one of the last elements of old-growth forests to develop in intensively logged stands. Retention of small groups of large snags and live trees exhibiting evidence of disease or physical defects would ensure availability of denning structures after logging.
Little evidence for visual monitoring of vigilance in zebra finches
Authors: Beauchamp G
Published: November 2002

Several models of vigilance assume that it can be adjusted in response to levels maintained by companions. However, the assumption of visual monitoring of vigilance has received little empirical scrutiny. Various treatments in a laboratory study manipulated the ability of zebra finches (Taenopygia guttata) foraging in pairs to monitor visually the vigilance of companions. In one treatment, the insertion of an uncovered partition allowed members of a pair to monitor, if needed, the vigilance of their companion. The addition of a partial cover to the partition in a further treatment eliminated any visual monitoring of vigilance by companions on either side of the partition while leaving the view from the rest of the cage unaltered. The final treatment, without a partition, allowed the feeding behaviour of unrestricted birds to be examined. As birds spent most of their time feeding or vigilant, feeding rate was considered a proxy for vigilance. After an initial difference in feeding rate across treatments, related perhaps to the novelty associated with the insertion of a partition, birds obtained food at a similar rate whether visual monitoring of vigilance was possible or not and whether individuals were physically separated or not. In agreement with recent empirical and theoretical findings, the study provides little evidence for visual monitoring of vigilance in birds.
Diving schedules of Common Loons in varying environments
Authors: Nocera Joseph J , Burgess Neil M
Published: November 2002

Many species of diving birds adjust their foraging behaviour in response to variation in their environment. The Common Loon (Gavia immer) is a visually oriented predator sensitive to environmental variation, yet little is known about the flexibility of its diving behaviour. We tested the hypothesis that loons adjust their diving schedules by increasing or decreasing the dive duration during foraging bouts to accommodate environmental variation during the breeding season. The dive duration and dive-pause components of the loon dive cycle did not vary among lakes with different lake chemistry, lake morphometry, mercury levels in their blood, or fish abundance. We observed some variation among loons in different stages of breeding in mean dive-pause intervals. The dive-pause component of the diving cycle of Common Loons does not seem to be related to the amount of time spent underwater. To our knowledge, this is the first report of such a nonlinear relationship in diving birds. We propose that loons vary the components of their diving behaviour independently and seem to alter their diving time budgets regardless of the external stimuli we addressed. This unresponsive diving schedule may make loons susceptible to catastrophic changes in prey densities within their foraging areas, as they are obliged to forage on one, or very few, lakes. Conversely, loons may only forage in lakes with fish abundance above a certain minimum threshold and preferentially avoid lakes with reduced prey abundance.
Responses of body components to changes in the energetic demand throughout the breeding stages of rhinoceros auklets
Authors: Niizuma Yasuaki , Araki Yoko , Mori Hiroe , Takahashi Akinori , Watanuki Yutaka
Published: November 2002

When rearing chicks, seabirds increase their daily energy expenditures during commuting flights between foraging areas and breeding colonies, owing to the heavy food loads. At this time, parents are expected to enlarge the size of their energy-supplying organs in response to the increased energy demands but reduce their total body mass to minimize the energetic cost of flight. The changes in body components of 40 incubating and chick-rearing rhinoceros auklets (Cerorhinca monocerata) were examined. Chick-rearing auklets did not have larger energy-supplying organs and breast muscles than incubating ones. However, chick-rearing auklets had greater ash composition, but smaller lipid contents, of breast muscles than incubating ones, whereas the former had a mass of water and protein similar to the latter. Male and female auklets lost a mean of 32.6 and 32.1 g in body mass between incubation and chick-rearing stages, mainly via loss of lipid reserves, which consequently reduces flight costs by 9.9 and 9.1%, respectively. Performance of commuting flight could be improved through changes in breast muscle compositions and reductions in total body mass. Although auklets did not enlarge their energy-supplying organs, their body conditions could be maintained within the same phase between the breeding stages.
Sex differences in melanotic encapsulation responses (immunocompetence) in the damselfly Lestes forcipatus Rambur
Authors: Yourth Christopher P , Forbes Mark R , Baker Robert L
Published: November 2002

A few studies have shown that male and female invertebrates differ in immunity and that these differences appear related to differences in sexual dimorphism and gender differences in life histories. Melanotic encapsulation of foreign objects in insects is one form of immunity. The damselfly Lestes forcipatus Rambur is moderately sexually dimorphic, and much is known about patterns of mass gain in congeners relating to differences in life history between males and females. In this study, females were more immunoresponsive than males under controlled temperatures, following emergence, and at a time when parasitic mites were challenging these hosts. However, males and females that overlapped in mass at emergence did not differ in their immune responses. Males in better condition at emergence were more immunoresponsive than lighter males, but this relation was not found in females. Sex differences in immune expression may have implications for how females versus males are able to deal with challenges from parasites, under varying environmental conditions.
Morphological changes to black-footed ferrets (Mustela nigripes) resulting from captivity
Authors: Wisely S M , Ososky J J , Buskirk S W
Published: November 2002

Captive breeding of endangered species carries risks associated with small population size and domestication. The black-footed ferret (Mustela nigripes) was among the first endangered species bred in captivity. We documented morphological changes to the species after >10 years of captive breeding. We measured 9 dental or cranial traits on 109 skulls; 85 specimens were collected prior to captivity and 24 specimens were of captive-born animals. Skulls of captive animals were 56% smaller than skulls from precaptive animals and were 310% smaller than skulls of animals collected near the founding population, suggesting that changes occurred in captivity rather than from sample bias in the founders of the captive population. Skull size did not correlate with inbreeding coefficients of captive animals, eliminating the possibility that black-footed ferrets were smaller because of the effects of inbreeding depression or overdominance. Although reintroduced animals were smaller than historical animals, we recommended no alterations to the current management because intentional selection for body size might further reduce genetic variation in a genetically impoverished species. We hypothesize that reintroduced individuals will return to historical body sizes rapidly, owing either to release of environmental stresses or to natural selection for larger size.
Gap crossing by chipmunks: an experimental test of landscape connectivity
Authors: Bowman Jeff , Fahrig Lenore
Published: November 2002

Eastern chipmunks (Tamias striatus) are forest specialists common to eastern North America. Numerous studies suggest that chipmunks require fencerow corridors between woodlots to maintain functional connectivity in agricultural landscapes. We tested this hypothesis by conducting a homing experiment to assess whether chipmunks would cross nonforested gaps of different sizes. Chipmunks in 11 landscapes were translocated a constant distance of 220250 m across gaps ranging in size from 0 (continuous forest) to 240 m (mostly gap). Logistic regression analysis demonstrated that the probability of an adult chipmunk returning to its home range was not related to the size of the gap that had to be crossed (χ2 = 0.781, n = 60, P = 0.377, ρ2 = 0.011). Chipmunks crossed the entire range of gap sizes and there was no evidence of a threshold in connectivity. These results suggest that forest woodlots may be functionally connected for chipmunks even without fencerow corridors, and that landscape configuration in the study area may not have isolating effects on chipmunk populations. More empirical studies are required to identify whether functional connectivity thresholds are present in mammal populations as theoretical studies suggest.
Ultrastructural study of the olfactory organ in adult and developing European sea bass,Dicentrarchus labrax
Authors: Diaz J P , Prié-Granié M , Blasco C , Noëll T , Connes R
Published: November 2002

The olfactory organ of the European sea bass (Dicentrarchus labrax) in adults and during development has been studied by light microscopy and by transmission and scanning electron microscopy. This organ includes two cavities, each extended by an accessory sac and opening to the outside through two nostrils. It contains a rosette consisting of about forty lamellae. The olfactory epithelium is characterized by the presence of two types of receptor cells, ciliated or with microvilli, and numerous ciliated nonsensory cells. Rod cells, essentially found in the altered epithelia of farmed bass, and rodlet cells are also observed. The olfactory organ forms very early in the developmental process. Two olfactory pits holding both types of sensory receptors appear 24 h before hatching. The ciliated nonsensory cells only appear at the end of the endotrophic period, shortly before the mouth opens. Although it is rather unspectacular during the larval stage, the development of the olfactory organ is characterized at the start of the juvenile stage by three important events: the formation of the nostrils, the hollowing of the accessory sacs, and the development of the rosette. This is created by raising the floor of the cavity and forming successive folds, which are the lamellae where the sensory epithelium is found.
Effects of body size and mass on running speed of male yellow-pine chipmunks (Tamias amoenus)
Authors: Schulte-Hostedde Albrecht I , Millar John S
Published: November 2002

Male-biased sexual size dimorphism in mammals is usually attributed to the success of large males in intrasexual combat for mates. However, mating success may be determined by contests that are not combative. In the mating chase of the yellow-pine chipmunk (Tamias amoenus), a mammalian species with female-biased sexual size dimorphism, fast males may have an advantage in acquiring matings with estrous females. However, the effects of intraspecific variation in body size on running speed are not obvious; heavy individuals may run more slowly than light individuals because excess mass can be a hindrance to locomotion, but individuals that are structurally large may run faster than small individuals because of longer stride length. We examined the effects of both body mass and structural size on running speed in male yellow-pine chipmunks using manipulated runs in which male chipmunks were chased over a known distance. Structurally large male chipmunks had faster running speeds than small males, potentially giving large males an advantage when chasing estrous females. However, small male chipmunks are known to be aggressively dominant over large males. This leads to a potential trade-off in male body size between two behavioural components of mating success (running speed and dominance) that may constrain the evolution of male body size, ultimately leading to female-biased sexual size dimorphism.
Home-range size and habitat selection by American marten (Martes americana) in Labrador
Authors: Smith Adam C , Schaefer James A
Published: November 2002

Variation in home-range size can be related to different factors at different spatial scales. This study examined the patterns of home-range size and habitat selection of American marten (Martes americana) in southeastern Labrador, a region of extensive and pristine forests. Over 1.5 years, we monitored 28 radio-collared marten and compared the availability of habitat types with their use. Marten avoided areas with low productivity and low canopy cover (<20%) but showed no selection for tree species composition or cover among more productive forests. Mean home ranges for both sexes (males, 45.0 km2; females, 27.6 km2) were exceptionally large, more than double the largest values previously recorded for the species. We analyzed variation in home-range size at two scales: within our study population and, using data from the literature, among populations across the species range in relation to temperature, snow cover, and body size. Within our population, home-range area was positively related to the proportion of bog and less productive, scrub forests in the home range. Among populations, differences in home-range size were not significantly related to any of the tested factors.
A MINOR SUBSPACE ALGORITHM BASED ON NEURAL STIEFEL DYNAMICS
Authors: FIORI SIMONE
Published: November 2002

In the present paper we investigate iterative minor subspace analysis computation by describing a neural approach based on weight flow on Stiefel manifold and by discussing four neural algorithms and a purely algebraic algorithm known from the scientific literature. A comparison of numerical experimental results and computational complexity estimates confirms the effectiveness and efficiency of the proposed approach.
SELECTING NEURAL NETWORKS FOR A COMMITTEE DECISION
Authors: VERIKAS ANTANAS , LIPNICKAS ARUNAS , MALMQVIST KERSTIN
Published: November 2002

To improve recognition results, decisions of multiple neural networks can be aggregated into a committee decision. In contrast to the ordinary approach of utilizing all neural networks available to make a committee decision, we propose creating adaptive committees, which are specific for each input data point. A prediction network is used to identify classification neural networks to be fused for making a committee decision about a given input data point. The jth output value of the prediction network expresses the expectation level that the jth classification neural network will make a correct decision about the class label of a given input data point. The proposed technique is tested in three aggregation schemes, namely majority vote, averaging, and aggregation by the median rule and compared with the ordinary neural networks fusion approach. The effectiveness of the approach is demonstrated on two artificial and three real data sets.
AN APPROACH TO IMPROVE WANG–SMITH CHAOTIC SIMULATED ANNEALING
Authors: ZHENG LIYING , WANG KEJUN , TIAN KAI
Published: November 2002

Previous research shows that Wang–Smith chaotic simulated annealing, which employs a gradually decreasing time-step, has only a scaling effect to computational energy of the Hopfield model without changing its shape. This makes the net has sensitive dependence on the value of damping factor. Considering Chen–Aihara chaotic simulated annealing with decaying self-coupling has a shape effect to computational energy of the Hopfield model, a novel approach to improve Wang–Smith chaotic simulated annealing, which reaps the benefits of Wang–Smith model and Chen–Aihara model, is proposed in this paper. With the aid of this method the improved model can affect on computational energy of the Hopfield model from scaling and shape. By adjusting the time-step, the improved neural network can also pass from a chaotic to a non-chaotic state. From numerical simulation experiments, we know that the improved model can escape from local minima more efficiently than original Wang–Smith model.
GENETIC PROGRAMMING OF POLYNOMIAL HARMONIC NETWORKS USING THE DISCRETE FOURIER TRANSFORM
Authors: NIKOLAEV NIKOLAY Y. , IBA HITOSHI
Published: November 2002

This paper presents a genetic programming system that evolves polynomial harmonic networks. These are multilayer feed-forward neural networks with polynomial activation functions. The novel hybrids assume that harmonics with non-multiple frequencies may enter as inputs the activation polynomials. The harmonics with non-multiple, irregular frequencies are derived analytically using the discrete Fourier transform. The polynomial harmonic networks have tree-structured topology which makes them especially suitable for evolutionary structural search. Empirical results show that this hybrid genetic programming system outperforms an evolutionary system manipulating polynomials, the traditional Koza-style genetic programming, and the harmonic GMDH network algorithm on processing time series.
NEURAL ADAPTIVE CONTROL OF NONLINEAR MULTIVARIABLE SYSTEMS WITH APPLICATION TO A CLASS OF INVERTED PENDULUMS
Authors: HE SHOULING
Published: November 2002

In this paper multilayer neural networks (MNNs) are used to control the balancing of a class of inverted pendulums. Unlike normal inverted pendulums, the pendulum discussed here has two degrees of rotational freedom and the base-point moves randomly in three-dimensional space. The goal is to apply control torques to keep the pendulum in a prescribed position in spite of the random movement at the base-point. Since the inclusion of the base-point motion leads to a non-autonomous dynamic system with time-varying parametric excitation, the design of the control system is a challenging task. A feedback control algorithm is proposed that utilizes a set of neural networks to compensate for the effect of the system's nonlinearities. The weight parameters of neural networks updated on-line, according to a learning algorithm that guarantees the Lyapunov stability of the control system. Furthermore, since the base-point movement is considered unmeasurable, a neural inverse model is employed to estimate it from only measured state variables. The estimate is then utilized within the main control algorithm to produce compensating control signals. The examination of the proposed control system, through simulations, demonstrates the promise of the methodology and exhibits positive aspects, which cannot be achieved by the previously developed techniques on the same problem. These aspects include fast, yet well-maintained damped responses with reasonable control torques and no requirement for knowledge of the model or the model parameters. The work presented here can benefit practical problems such as the study of stable locomotion of human upper body and bipedal robots.
AN MLP TRAINING ALGORITHM TAKING INTO ACCOUNT KNOWN ERRORS ON INPUTS AND OUTPUTS
Authors: SVENSSON J.
Published: November 2002

A training algorithm is introduced that takes into account a priori known errors on both inputs and outputs in an MLP network. The new cost function introduced for this case is based on a linear approximation of the network function over the input distribution for a given input pattern. Update formulas, in the form of the gradient of the new cost function, is given for a MLP network, together with expressions for the Hessian matrix. This is later used to calculate error bars in a Bayesian framework. The error bars thus derived are discussed in relation to the more commonly used width of the target posterior predictive distribution. It will also be shown that the taking into account of known input uncertainties in the way suggested in this article will have a strong regularizing effect on the solution.
A COMPARATIVE STUDY ON KERNEL-BASED PROBABILISTIC NEURAL NETWORKS FOR SPEAKER VERIFICATION
Authors: YIU K. K. , MAK M. W. , KUNG S. Y.
Published: November 2002

This paper compares kernel-based probabilistic neural networks for speaker verification based on 138 speakers of the YOHO corpus. Experimental evaluations using probabilistic decision-based neural networks (PDBNNs), Gaussian mixture models (GMMs) and elliptical basis function networks (EBFNs) as speaker models were conducted. The original training algorithm of PDBNNs was also modified to make PDBNNs appropriate for speaker verification. Results show that the equal error rate obtained by PDBNNs and GMMs is less than that of EBFNs (0.33% vs. 0.48%), suggesting that GMM- and PDBNN-based speaker models outperform the EBFN ones. This work also finds that the globally supervised learning of PDBNNs is able to find decision thresholds that not only maintain the false acceptance rates to a low level but also reduce their variation, whereas the ad-hoc threshold-determination approach used by the EBFNs and GMMs causes a large variation in the error rates. This property makes the performance of PDBNN-based systems more predictable.
PREDICTABILITY IN RT-LEVEL DESIGNS
Authors: SRIVASTAVA ANKUR , KURSUN EREN , SARRAFZADEH MAJID
Published: November 2002

The primary objective of this paper is to provide an initial impetus to predictability driven design flow. Predictability is the quantified form of accuracy. The novelty lies in defining and using the idea of predictability. In order to illustrate the basic concepts we focus on the power estimation problem in RT-Level designs. Our experiments showed that predictability at RT-Level could be improved by making the resource delay constraints more stringent. This procedure may come with increased power dissipation. We present an optimal pseudo-polynomial time algorithm to optimize predictability while keeping the increase in power dissipation within a budget. We further extend this algorithm to generate an ∊-approximate solution in polynomial time where ∊ is a user defined parameter. The algorithm probably generates solutions that differ at-most ∊C max from the optimal. The future work would include extending the concept of predictability to other levels of design flow and other cost function. We envision a design automation system which does effective tradeoff between predictability and cost hence enabling efficient design exploration.
BOOTSTRAP MONTE CARLO WITH ADAPTIVE STRATIFICATION FOR POWER ESTIMATION
Authors: HUANG HENG-LIANG , JOU JING-YANG
Published: November 2002

Monte Carlo approach for power estimation is based on the assumption that the samples of power are Normally distributed. However, the power distribution of a circuit is not always Normal in the real world. In this paper, the Bootstrap method is adopted to adjust the confidence interval and redeem the deficiency of the conventional Monte Carlo method. Besides, a new input sequence stratification technique for power estimation is proposed. The proposed technique utilizes a multiple regression method to compute the coefficient matrix of the indicator function for stratification. This new stratification technique can adaptively update the coefficient matrix and keep the population of input vectors in a better stratification status. The experimental results demonstrate that the proposed Bootstrap Monte Carlo method with adaptive stratification can effectively reduce the simulation time and meet the user-specified confidence level and error level.
POWER-AWARE BUS ENCODING TECHNIQUES FOR I/O AND DATA BUSES IN AN EMBEDDED SYSTEM
Authors: CHENG WEI-CHUNG , PEDRAM MASSOUD
Published: November 2002

Microprocessors with built-in Liquid Crystal Device (LCD) controllers and equipped with Flash ROM are common in mobile computing applications. In the first part of the paper, a software-only encoding technique is proposed to reduce the power consumption of the processor-memory bus when displaying an image on the LCD. Based on the translation mechanism of the LCD controller, the approach of this paper is to start with the palette as a coding table for the pixel buffer and then reassign the codes according to the image characteristics. Experimental results prove the efficacy of this approach; power reduction reaches 29% for text-based and 17% for graphics-based images. In the second part of the paper, another software-only encoding technique is presented to reduce the transitions on the processor-Compact Flash bus. The device driver in a Linux operating system is modified to perform Bus-Invert encoding when the data is read from or written to a Compact Flash file system. With minimal software overhead, the transitions on the bus are reduced by up to 25%.
AN OPTIMIZATION-BASED MULTIPLE-VOLTAGE SCALING TECHNIQUE FOR LOW-POWER CMOS DIGITAL DESIGN
Authors: YEH YI-JONG , KUO SY-YEN
Published: November 2002

In this paper, we propose a voltage scaling technique with multiple supply voltages for low-power designs. We adopt the path sensitization technique and release the clustering constraint used by the previous works. Our technique first operates the gates with the lowest feasible supply voltages and then uses an existing path selection algorithm for optimization. Experiments are conducted on all ISCAS85 benchmarks and the results show that significant power can be further reduced by our technique in comparison with the previous works. Furthermore, the results generated by our technique are close to the optimal values.
REDUCE THE MEMORY BANDWIDTH OF 3D GRAPHICS HARDWARE WITH A NOVEL RASTERIZER
Authors: CHEN CHENG-HSIEN , LEE CHEN-YI
Published: November 2002

Currently, memory bandwidth has become the main bottleneck in graphics system. Reducing the memory access can reduce the power consumption and boost overall system performance. Low power technique is more important for graphics applications on hand-held or mobile device. In this paper, we propose a novel visibility driven rasterizer to reduce the memory access and operations on invisible pixels. It integrates with two-level hierarchical Z-buffer to do visibility driven rasterization. The rasterization scheme is tile-order scan-line based, and the rasterizer can smartly change the tile-size depending on the triangle size. This technique can balance the rasterization loading under different triangles. Moreover, we propose a fast visibility test algorithm to quickly reject a group of pixels within the tile. Simulation results show that the overall bandwidth reduction can be up to 60% under our test images.
DESIGN OF MODIFIED FOUR-PHASE CMOS CHARGE PUMPS FOR LOW-VOLTAGE FLASH MEMORIES
Authors: LIN HONGCHIN , CHEN NAI-HSIEN , LU JAINHAO
Published: November 2002

A new four-phase clock scheme for the four-phase charge pumping circuits using standard 0.5 μm CMOS technology at low supply voltages to generated high boosted voltages is proposed. Boosted clocks without high drivability are applied on the capacitors coupled to the gates of the main charge transfer transistors to compensate body effects. Thus, the high-voltage clock generation circuit can be easily achieved for clock frequency of 10 MHz. Due to the nearly ideal pumping gain per stage, the design methodology to optimize power efficiency is also presented. With the new clock scheme, it can efficiently pump to 9 V at supply voltage of 1 V using 10 stages by simulations, while pump to 4.7 V at supply voltage of 1.5 V using four stages by measurements.
A LOW-POWER PARAMETERIZED HARDWARE DESIGN FOR THE ONE-DIMENSIONAL DISCRETE FOURIER TRANSFORM OF VARIABLE LENGTHS
Authors: GUO JIUN-IN , LIN CHIEN-CHANG , CHIEN CHIH-DA
Published: November 2002

This paper presents a new low-power parameterized hardware design for the one-dimensional (1D) discrete Fourier transform (DFT) of variable lengths. By combining the cyclic convolution formulation, block-based distributed arithmetic (BDA), and Cooley–Tukey decomposition algorithm together, we have developed a parameterized hardware design for the DFT of variable lengths ranging from 256 to 4096 points and with different modes of performance. The proposed design can perform different lengths of DFT computation through the configuration of parameters, which not only provides the flexibility in computing different length DFT but also facilitates the performance-driven design considerations in terms of power consumption and processing speeds, that is, we can configure the proposed design in different modes of performance by setting different parameters. This feature is beneficial to developing a parameterized DFT soft Intellectual Property (IP) core or hard IP core for meeting the system requirements of different silicon-on-a-chip (SOC) applications as compared with the existing fixed length DFT designs.
LOW-POWER HIGH-SPEED CLASS-AB BUFFER AMPLIFIERS FOR LIQUID-CRYSTAL DISPLAY SIGNAL DRIVER APPLICATION
Authors: LU CHIH-WEN
Published: November 2002

Two types of low-power, high-speed, but with a large input dynamic range and output swing class-AB output buffer amplifiers which are suitable for the liquid-crystal display signal driver application are proposed. The driving capabilities of the circuits are achieved by adding comparators which sense the rising and falling edges of the input waveform and then turn on an auxiliary driving transistor to help charging/discharging the output load. The auxiliary driving transistors stay at "off" in the stable state, thus drawing no static power. Hence, the buffers draw little current during static but have an improved driving capability during transients. They are demonstrated in a 0.6 μm CMOS technology. The measured data do show that the proposed output buffer circuits are very suitable for the application of liquid-crystal display signal driver.
PHASE LOCKING AND RESONANCES FOR STOCHASTIC EXCITABLE SYSTEMS
Authors: LONGTIN ANDRÉ
Published: November 2002

We investigate the phase locking of firing events in periodically forced stochastic excitable systems. Our study is motivated by the observation of randomly phase locked firing activity in a large number of neurons, especially those involved in transducing physical stimuli such as temperature, sound, pressure and electric fields. The purpose of our paper is to review our work on the biophysical origin of such firing patterns. Special attention is given to the constructive effect of noise, and to the connection between stochastic and deterministic resonances in such systems. We present new results on stochastic phase locking in the subthreshold and suprathreshold regimes, and on the non-monotonicity of the spectral amplification as a function of noise intensity. We also discuss current outstanding problems and potentially fruitful future research directions.
A QUANTUM CHEMISTRY GIAO MOLECULAR SITE APPROACH OF NMR CHEMICAL SHIFTS GENERALIZED TO THE WHOLE PERIODIC TABLE
Authors: VIEILLE LAETITIA , BERLU LILIAN , COMBOURIEU BRUNO , HOGGAN PHILIP
Published: November 2002

An accurate and rapid quantum chemistry approach to predicting chemical shifts is applied to 15 N natural abundance NMR spectra of benzothiazoles. This method is of interest in the study of toxic contaminants of biological media. A GIAO approach is used to calculate the nuclear shielding tensor in a perturbational scheme. Similar methods had previously been used for both ab initio and semi-empirical calculations programmed in Gaussian and MOPAC respectively but atomic orbitals specific to molecular sites are shown to improve accuracy in the present work. Some molecular sites are defined in order to polarize the molecular orbitals in the presence of the solvent interactions. For convenience, the extensions are carried out in an independent NMR module designed to work with the MOPAC package and the present application is generalized to the third row elements for the first time. This new theoretical work is described. The application to 15 N chemical shifts for benzothiazoles led to results within 0.5 ppm of values measured in this work. Structural investigations were carried out using the Gaussian98 suite of programs at the DFT B3LYP level of calculation over an extended basis set. These studies show the single chemical shift for benzothiazoles could be the result of rapid tautomeric equilibria. Further investigations show that solvent interactions involving hydrogen bonds should also be taken into account.
THE VIRTUOSIC EXEGESIS OF THE BRAHMAVADIN AND THE RABBI
Authors: Lubin Timothy
Published: November 2002

Despite the vast spatial and theological gulfs separating the Rabbinic and Brahmanic communities, their respective intellectual projects have a number of analogous features. My discussion will (1) outline for each tradition a set of interpretive strategies, showing how these two sets are strikingly similar in approach and logic. Then I will (2) propose that these resemblances are not entirely coincidental. They largely stem from a similar view of the object of study—Torah and the biblical text for the Rabbis, the sacrifice and its verbal articulation for the Brahmins—as eternal, not of human authorship, perfect in form, rich in hidden meanings, the criterion of right action and true knowledge. The exegete aims to fully internalize the sacred word, to perceive the world through it, and to uncover what is hidden in it. This much of my analysis might also be applicable to other traditions that regard themselves as possessing revelation, but (3) I argue that there are further parallels here in the direction these traditions carried their interpretive enterprise. In each tradition, the interpreters continued to build an edifice of ritual knowledge and interpretation even as the central rites were eclipsed by other forms of piety: whether because the cult became inaccessible (in the Diaspora) or unperformable (when the Temple was destroyed), or because it lost patronage (as appears to have happened in India). In tandem with the shift away from priestly sacrifice, each tradition promotes the ideal of study for its own sake, and the transfer of priestly functions to the learned householder.
Static characteristics of a piston-type pilot relief valve
Authors: Washio S , Nakamura Y , Yu Y
Published: November 2002

An oil hydraulic pilot relief valve was empirically investigated to fully understand its static performance. Constriction components which dominate the flow in the valve were individually examined in detail, revealing that the static relation between the pressure drop, flowrate and opening area for a constriction can be represented, not by the traditional hydraulic orifice equation which has always been used for the purpose, but by a new one including an additional pressure loss proportional to the flowrate and the fluid viscosity as well as inversely proportional to the square of the opening area. The new characteristic equation has consistently proved to predict the experimental findings in which a rise in oil temperature results in an increase in the piston displacement but causes little change as regards regulated pressure. It also turns out that, contrary to common preconceptions, the fluid force exerted on a poppet is negligible in the present case. It was discovered, on the other hand, that fluid force on a piston can be influential and works to increase the pilot flow.
Identification of two functionally different classes of maxima in random surface waveforms
Authors: Whitehouse D. J.
Published: November 2002

It is shown that it is possible to separate the equation of the density of peaks of a random surface profile into the density of dependent peaks and the density of independent peaks. As these two types of peaks behave differently under load the ability to separate them has to be important in contact theory. Practical results are shown that verify the theory.