bluuebunny/crossref_metadata_2025 huggingface dataset:
Chemical Neuroecology and Community Dynamics
Authors: Ferrer Ryan P. , Zimmer Richard K.
Published: July 2009

Chemical neuroecology examines the relationships between chemosensory physiology, behavior, and population and community dynamics. A keystone species, for example, is one whose impact on communities is far greater than would be predicted from its relative abundance and biomass. Neurotoxins, then, could function in keystone roles. Rare within natural habitats, they exert strong effects on species interactions at multiple trophic levels. Effects of two guanidine alkaloids, tetrodotoxin (TTX) and saxitoxin (STX), coalesce neurobiological and ecological perspectives. These potent neurotoxins function as chemical defenses by binding to voltage‐gated sodium channels on nerve and muscle cells. When borrowed by resistant consumer species, however, they are used in chemical defense against higher‐order predators or as chemosensory excitants in mediating critical behavioral interactions. Through a combination of diverse physiological traits, TTX and STX exert profound impacts reverberating across multiple trophic levels and determining a wide range of community‐wide attributes. Such traits ultimately render TTX and STX fully functional as keystone molecules, with vast ecological consequences for species assemblages and rates of material exchange.
Dynamics of Nasal Chemesthesis
Authors: Wise Paul M. , Zhao Kai , Wysocki Charles J.
Published: July 2009

Dynamics, or how stimulation occurs over time, influences the somatosensory impact of volatile chemicals. Within an experimental session, sensation waxes with steady presentation over seconds to minutes, may reach a plateau, and then may fade. Long‐term occupational exposure can desensitize the trigeminal system. Short‐ and long‐term dynamics might be mediated by different mechanisms. For brief intranasal exposures (i.e., up to about 10 seconds), studies have systematically manipulated both time (duration of exposure) and concentration to maintain a fixed perceived intensity or a fixed level of detection. A simple mass integration model describes the trade‐off between concentration and time quite well: a fixed‐ratio increase in duration compensates for a fixed‐ratio decrease in concentration. However, for most compounds, more than a two‐fold increase in duration are required to compensate for cutting concentration in half. For example, for ethanol, an increase in duration of about six‐fold are required. For such compounds that display highly imperfect integration, a fixed number of molecules might have a much greater sensory impact when presented over 0.2 seconds than over 0.5 seconds. Nasal chemesthesis may be temporally sluggish compared to olfaction, but fine‐grained dynamics still matter. Time–intensity ratings of nasal irritation from dynamic stimuli also support this conclusion. Although integration is generally imperfect, compounds vary widely in how far they fall short of perfect time–concentration trading. Current studies use a structure–activity approach to determine how molecular parameters correlate with how well a compound integrates over time.
Perceptual and Sensorimotor Differences between “Good” and “Poor” Olfactory Mental Imagers
Authors: Rouby Catherine , Bourgeat Fanny , Rinck Fanny , Poncelet Johan , Bensafi Moustafa
Published: July 2009

Like odor perception, odor imagery is characterized by wide variability between individuals. The present two‐part study sought to assess whether this inter‐individual variability is underlain by behavioral differences in actual odor perception. In study 1, subjects judged the intensity, pleasantness, familiarity and edibility of 3 odorants. Participants were split into two olfactory imagery groups (“good” versus “poor” olfactory imagers) according to their scores on an imagery questionnaire. Results showed that good olfactory imagers judged all odors as more familiar and more edible than did poor olfactory imagers. Study 2 sought to determine whether these effects derived from a particular strategy of reenacting olfactomotor responses to smells on the part of good olfactory imagers, by recording their sniffs during odor perception. Results revealed that good olfactory imagers sniffed all odors longer and, again, judged these same odors as more edible and familiar. This supports the hypothesis of more complete odor processing and better access to odor semantics in good olfactory imagers.
Perceptual and Neural Pliability of Odor Objects
Authors: Gottfried Jay A. , Wu Keng Nei
Published: July 2009

A key function of the sense of smell is to guide organisms towards rewards and away from dangers. However, because relatively few volatile chemicals in the environment carry intrinsic biological value, the meaning of an odor often needs to be acquired through learning and experience. The tremendous perceptual and neural plasticity of the olfactory system provides a design that is ideal for the establishment of links between odor cues and behaviorally relevant events, promoting appropriate adaptive responses to foods, friends, foes, and mates. This article describes recent human neuroimaging data showing the dynamic effects of olfactory perceptual learning and aversive conditioning on the behavioral discrimination of odor objects, with parallel plasticity and reorganization in the posterior piriform and orbitofrontal cortices. The findings presented here highlight the important role of experience in shaping odor object perception and in ensuring the human sense of smell achieves its full perceptual potential.
Modulation of Taste Sensitivity by GLP‐1 Signaling in Taste Buds
Authors: Martin Bronwen , Dotson Cedrick D. , Shin Yu‐Kyong , Ji Sunggoan , Drucker Daniel J. , Maudsley Stuart , Munger Steven D.
Published: July 2009

Modulation of sensory function can help animals adjust to a changing external and internal environment. Even so, mechanisms for modulating taste sensitivity are poorly understood. Using immunohistochemical, biochemical, and behavioral approaches, we found that the peptide hormone glucagon‐like peptide‐1 (GLP‐1) and its receptor (GLP‐1R) are expressed in mammalian taste buds. Furthermore, we found that GLP‐1 signaling plays an important role in the modulation of taste sensitivity: GLP‐1R knockout mice exhibit a dramatic reduction in sweet taste sensitivity as well as an enhanced sensitivity to umami‐tasting stimuli. Together, these findings suggest a novel paracrine mechanism for the hormonal modulation of taste function in mammals.
Age‐related Hearing Loss
Authors: Frisina Robert D.
Published: July 2009

Loss of sensory function in the aged has serious consequences for economic productivity, quality of life, and healthcare costs in the billions each year. Understanding the neural and molecular bases will pave the way for biomedical interventions to prevent, slow, or reverse these conditions. This chapter summarizes new information regarding age changes in the auditory system involving both the ear (peripheral) and brain (central). A goal is to provide findings that have implications for understanding some common biological underpinnings that affect sensory systems, providing a basis for eventual interventions to improve overall sensory functioning, including the chemical senses.
Behavioral Studies of Umami
Authors: Delay Eugene R. , Eddy Meghan C. , Eschle Benjamin K.
Published: July 2009

Psychophysical research with rats and mice has been instrumental in understanding umami taste transduction and perception. Although early studies suggested that an NMDA‐like receptor detected substances that elicit an umami taste, studies using behavioral methods with both rats and mice indicate that the picture is much more complex. When the G protein‐coupled receptor T1R1+T1R3 was discovered, it was believed to be the umami receptor and a more broadly tuned L‐amino acid receptor. However, since then a number of behavioral studies, like molecular and physiological studies, report evidence that other receptors may contribute to umami taste. For example, T1R3 knockout mice (KO) have only slightly elevated detection thresholds for monosodium glutamate (MSG) and L‐alanine. In conditioned taste aversion studies, T1R3 KO mice show bidirectional generalization of the aversion between MSG and L‐alanine, suggesting that these substances have similar tastes. However, these KO mice can discriminate between the tastes of the two substances, indicating other receptors also respond to these amino acids. (RS)‐α‐cycloprophy‐4‐phosphonophenylglycine (CPPG), a potent mGluR4 antagonist, decreases an aversion to MSG in rats while increasing the strength of generalization of the aversion to L‐arginine or L‐serine. These behavioral studies suggest that glutamate can activate several putative receptors, most notably T1R1+T1R3 and taste‐mGluR4, and possibly NMDA‐like receptors or taste‐mGluR1. These receptors generate similar but not identical sensations which, when combined, form a complex perception identified as umami. Further, these studies suggest that afferent signaling from T1R1+T1R3 and taste‐mGluR4 likely combine to generate the taste sensations associated with other L‐amino acids.
Autobiographical Odor Memory
Authors: Larsson Maria , Willander Johan
Published: July 2009

This overview focuses on autobiographical odor memory and how information evoked by the olfactory sense may differ from memories evoked by visual or verbal information. Three key topics are addressed: (a) age distributions of evoked memories; (b) phenomenological experience; and (c) semantic processing. Current evidence suggests that memories triggered by olfactory information are localized to the first decade of life (< 10 years) rather than to young adulthood (10–30 years) which is the typical finding for memories evoked by verbal and visual information. Further, empirical evidence indicates that odor evoked memories are more emotional, associated with stronger feelings of being brought back in time, and have been thought of less often as compared to memories evoked by other sensory cues. Finally, previous observations of a significant impact of semantic influences on olfactory processing may also be generalized to retrieval of odor evoked autobiographical information. Specifically, both the age distribution and phenomenological qualities are affected by explicit knowledge of the odor cue. Taken together, the overall pattern of findings indicates that personal memories evoked by olfactory information are different from memories evoked by verbal or visual information.
Insect Olfactory Receptor Complex Functions as a Ligand‐gated Ionotropic Channel
Authors: Touhara Kazushige
Published: July 2009

In general, each insect olfactory sensory neuron expresses one member of the olfactory receptor (OR) gene family along with the highly conserved Or83b co‐receptor, and the two ORs form a heteromeric complex to function as a chemosensor. Here we provide evidence that heteromeric insect ORs comprise a novel class of ligand‐activated nonselective cation channels. Heterologous cells expressing silk moth, fruit fly, or mosquito heteromeric OR complexes exhibited extracellular calcium influx and cation‐nonselective ion conductance upon odorant or pheromone stimulation. G protein‐mediated signaling was negligible in producing the current elicited by ligand activation of insect ORs. Direct evidence for ligand‐gated channels was obtained by outside‐out patch‐clamp single‐channel recording of Xenopus oocyte and HEK293T cell membranes expressing insect OR complexes. The olfactory signal transduction mechanism in insects is clearly distinct from that in vertebrates and appears to be a unique strategy that insects have acquired to respond to the olfactory environment.
Low‐level Mechanisms for Processing Odor Information in the Behaving Animal
Authors: Wachowiak Matt , Wesson Daniel W. , Pírez Nicolás , Verhagen Justus V. , Carey Ryan M.
Published: July 2009

Sensory processing is typically thought to act on representations of sensory stimuli that are relatively fixed at low levels in the nervous system and become increasingly complex and subject to modulation at higher levels. Here we present recent findings from our laboratory demonstrating that, in the olfactory system, odor representations in the behaving animal can be transformed at low levels—as early as the primary sensory neurons themselves—via a variety of mechanisms. First, changes in odor sampling behavior, such as sniffing, can dramatically and rapidly alter primary odor representations by changing the strength and temporal structure of sensory input to the olfactory bulb, effectively shaping which features of the olfactory landscape are emphasized and likely altering how information is processed by the olfactory bulb network. Second, neural substrates exist for presynaptically modulating the strength of sensory input to the bulb as a function of behavioral state. The systems most likely to be involved in this modulation—cholinergic and serotonergic centrifugal inputs to the bulb—are linked to attention and arousal effects in other brain areas. Together, sniffing behavior and presynaptic inhibition have the potential to mediate, or at least contribute to, sensory processing phenomena, such as figure–ground separation, intensity invariance, and context‐dependent and attentional modulation of response properties. Thus, “high order” processing can occur even before sensory neurons transmit information to the brain.
Role of Cortical Feedback in Regulating Inhibitory Microcircuits
Authors: Strowbridge Ben W.
Published: July 2009

The olfactory bulb contains an impressive array of specialized inhibitory local circuits. The most frequent inhibitory microcircuit in this brain region is the reciprocal dendrodendritic synapse formed between the lateral dendrites of mitral cells and distal dendritic spines of GABAergic granule cells. Recent work discussed in this review suggests that release of GABA from granule cell spines may reflect near‐coincident activation of both mitral cell–to–granule cell synapses and proximal excitatory synapses on granule cells that originate from pyramidal cells in piriform cortex. Recent work using two‐photon guided microstimulation demonstrated that proximal and distal excitatory synapses onto granule cells exhibit different forms of short‐term plasticity, with feedback inputs from piriform cortex facilitating when tested with brief (∼50 ms) interstimulus intervals. One consequence of this synaptic plasticity is that short duration, gamma‐frequency, oscillatory discharges in piriform cortical cells evoke summating excitatory postsynaptic potentials (EPSPs) in granule cells that effectively trigger action potentials. Piriform cortex stimulation can gate dendrodendritic inhibition onto mitral cells, presumably through the ability of EPSP‐driven action potentials in granule cells to temporarily relieve the tonic blockade of NMDA receptors by extracellular Mg2+ ions. Feedback projections in other CNS systems also may target inhibitory neurons, such as the backprojection from CA3 pyramidal neurons to GABAergic hilar interneurons. The ability of downstream processing areas to rapidly and selectively activate inhibitory interneurons in other brain regions may provide an important mechanism to dynamically modulate biological information processing.
Signaling Proteins that Regulate NaCL Chemotaxis Responses Modulate Longevity in C. elegans
Authors: Lans Hannes , Dekkers Martijn P. J. , Hukema Renate K. , Bialas Nathan J. , Leroux Michel R. , Jansen Gert
Published: July 2009

The lifespan of the nematode Caenorhabditis elegans is regulated by sensory signals detected by the amphid neurons. In these neurons, C. elegans expresses at least 14 Gα subunits and a Gγ subunit. We have identified seven sensory Gα subunits that modulate lifespan. Genetic experiments suggest that multiple sensory signaling pathways exist that modulate lifespan and that some G proteins function in multiple pathways, most of which, but probably not all, involve insulin/IGF‐1 like signaling. Interestingly, of the sensory G proteins involved in regulating lifespan, only one Gα probably functions directly in the detection of sensory cues. The other G proteins seem to function in modulating the sensitivity of the sensory neurons. We hypothesize that in addition to the mere detection of sensory cues, regulation of the sensitivity of sensory neurons also plays a role in the regulation of lifespan.
Psychophysical Effects of Nasal and Oral Inflammation
Authors: Welge‐Luessen Antje
Published: July 2009

Olfactory disorders are common in “nasal inflammation” even though the term is comprehensive and subsumes different kinds of entities which have to be differentiated. The most common cause of olfactory disorders are sinonasal disorders, which are defined as secondary smell disorders caused by diseases/pathologies in the nose/paranasal sinuses. According to the literature, sinonasal disorders represent—depending on the examined population—up to 72% of all olfactory disorders. In general, noninflammatory and inflammatory disorders are differentiated. Inflammatory disorders can be further classified into infectious or noninfectious disorders, both forms in which olfactory disorders can be present. For the clinician examining patients, the exact classification of the olfactory disorder is mandatory in order to choose appropriate treatment and counseling. Among the most common inflammatory disorders are acute rhinitis, allergic rhinitis, post‐upper respiratory tract infection and chronic rhinosinusitis, which are discussed in detail. In contrast to nasal inflammation, only little is known about oral inflammation and its psychophysical effects on taste function. Taste disorders following oral inflammation are briefly discussed.
In Vivo Fate Tracing Studies of Mammalian Taste Cell Progenitors
Authors: Thirumangalathu Shoba , Barlow Linda A.
Published: July 2009

In mammals, the homogeneous lingual epithelium in the process of development forms specialized placodal cells that undergo a series of morphogenetic changes to form a papilla. Taste buds appear in the papillary epithelium around birth and thus papillae serve to house the taste buds in the adult. However, evidence for a precise lineage relationship between a putative embryonic taste progenitor population and functional adult taste buds has so far been elusive and is primarily indirect. Also, mammalian taste papillae are reminiscent of epithelial appendages suggesting that the mesenchymal tissue of the papillae could be involved in the formation of these lingual structures. These major questions in the field of mammalian taste development have remained unanswered due to lack of fate mapping studies that would label embryonic cell populations and remain indelibly marked in the adult. Taking advantage of a genetic fate mapping approach to label cell populations both in the lingual epithelium and mesenchyme and following their fate during development would be an ideal way to assess each of these tissues contribution in taste bud formation. Fate mapping studies using tissue specific cre strains crossed with reporter alleles would uncover unique features in the formation of these specialized sensory cells and also provide us with an in vivo model system for taste organ specific experimental manipulations during development.
Epidemiological Studies of Taste Function
Authors: Snyder Derek J. , Bartoshuk Linda M.
Published: July 2009

Efforts to quantify the public health impact of chemosensation present significant challenges, including a strong need for testing methods suitable for field assessment. This discussion highlights several promising approaches to the population‐based study of taste function; it also identifies key principles that should be considered when adapting laboratory‐based taste tests for field use.
Surveying Food and Beverage Liking
Authors: Duffy Valerie B. , Hayes John E. , Sullivan Bridget S. , Faghri Pouran
Published: July 2009

Genetics, environmental exposures, and aging interact to produce variations in the perception or liking of taste, olfaction, and somatosensory sensations (i.e., chemosensation). Chemosensory variation can affect disease risk by influencing what people like and choose to eat from abundant supplies of desirable high‐fat, sweet, and salty foods and alcoholic beverages at the expense of less‐available or less‐liked vegetables. We contend that assessing dietary preference via liking–disliking surveys holds promise for linking chemosensation with dietary intake and health outcomes in population‐based studies. Typical intake measures (e.g., frequency surveys, dietary records) are difficult to complete and interpret. Because of memory issues and dietary restraint, individuals under‐ or overreport intakes, leading to inaccurate conclusions about diet–disease relationships. Surveying food and beverage liking is a time‐efficient, simple task that minimizes the cognitive limitations of intake measures. In the present study, women in a worksite health risk appraisal completed brief food frequency and liking surveys and reported their height and weight, and blood pressure was measured. While liking and intake measures for high‐fat and high‐fiber foods were correlated, only liking was associated with disease risk. In multiple regression models, women reporting greater liking for high‐fat foods and less liking for spicy foods had greater adiposity and/or blood pressure, controlling for age. These data, along with previous laboratory and community‐based studies, support that reported liking of high‐fat foods explains variability in adiposity and adiposity‐related outcomes. Hedonic measures appear to capture habitual intake of foods and beverages, are easy to implement in the field, and thus may increase understanding of how chemosensory variation modifies disease risk.
Pigmentary function and evolution of tyrp1 gene duplicates in fish
Authors: Braasch Ingo , Liedtke Daniel , Volff Jean‐Nicolas , Schartl Manfred
Published: July 2009

The function of the tyrosinase‐related protein 1 (Tyrp1) has not yet been investigated in vertebrates basal to tetrapods. Teleost fishes have two duplicates of the tyrp1 gene. Here, we show that the teleost tyrp1 duplicates have distributed the ancestral gene expression in the retinal pigment epithelium (RPE) and melanophores in a species‐specific manner. In medaka embryos, tyrp1a expression is found in the RPE and in melanophores while tyrp1b is only expressed in melanophores. In zebrafish embryos, expression of tyrp1 paralogs overlaps in the RPE and in melanophores. Knockdown of each zebrafish tyrp1 duplicate alone does not show pigmentary defects, but simultaneous knockdown of both tyrp1 genes results in the formation of brown instead of black eumelanin accompanied by severe melanosome defects. Our study suggests that the brown melanosome color in Tyrp1‐deficient vertebrates is an effect of altered eumelanin synthesis. Black eumelanin formation essentially relies on the presence of Tyrp1 and some of its function is most likely conserved from the common ancestor of bony vertebrates.
Coastal heath vegetation in central Norway
Authors: Nilsen Liv S. , Moen Asbjørn
Published: July 2009

This description of heath vegetation on the outermost coast of Trøndelag was based on 354 sample plots and 243 taxa. TWINSPAN, DCA and Ellenberg's indicator values were used to distinguish the vegetation types and to assess gradients in the vegetation. The aims were to make a phytosociological classification of the open coastal heath vegetation, find floristic gradients, compare the heath vegetation of central Norway with similar vegetation elsewhere and to evaluate the conservation values. The study area belongs to the southern boreal vegetation zone, and comparisons were made to Norwegian boreal and boreonemoral heaths, and to the sub‐montane heaths in the system of British plant communities. In the multivariate analyses, the data set was first separated on the poor–rich gradient. The four main units were separated by the second division of TWINSPAN and a further 16 communities were described. The poor heath communities had few vascular plants and a rather high number of bryophytes and lichens. The opposite was the situation in rich heaths. The studied heaths lack a number of typical species from further south in Europe, while some other species are common, that are absent or only occasionally occurring in coastal heath vegetation in nemoral and boreonemoral zones; e.g. Arctous alpinus, Arctostaphylos uva‐ursi, Betula nana, Chamaepericlymenum suecicum, Empetrum nigrum ssp. hermaphroditum, Rubus chamaemorus, Trientalis europaea, Vaccinium uliginosum, Carex nigra, Eriophorum angustifolium and E. vaginatum. A large number of western species occurs occasionally; Carex binervis is an exclusive, characteristic species for the heaths. In the European hierarchical phytosociological system, the communities were classified in five alliances: Erico–Sphagnion, Ericion tetralicis, Myrtillion boreale, Loiseleurio–Vaccinion and Kobresio–Dryadion. The rich heath types had the highest conservation value.
Variation in the determinants of power of chemically skinned human muscle fibres
Authors: Gilliver S. F. , Degens H. , Rittweger J. , Sargeant A. J. , Jones D. A.
Published: July 2009

We have explored the extent to which the maximal velocity of unloaded shortening (Vmax), the force generated per unit cross‐sectional area (P0) and the curvature of the force–velocity relationship (a/P0 in the Hill equation) contribute to differences in peak power of chemically skinned single fibres from the quadriceps muscle of healthy young male subjects. The analysis was restricted to type I and IIA fibres that contained a single type of myosin heavy chain on electrophoretic separation. Force–velocity relationships were determined from isotonic contractions of maximally activated fibres at 15°C. Mean (±s.d.) peak powers were 1.99 ± 0.72 watts per litre (W L−1) for type I fibres and 6.92 ± 2.41 W L−1, for type IIA fibres. The most notable feature, however, was the very large, sevenfold, range of power outputs within a single fibre type. This wide range was a consequence of variations in each of the three components determining power: P0, Vmax and a/P0. Within a single fibre type, P0 varied threefold, and Vmax and a/P0 two‐ to threefold. There were no obvious relationships between P0 and Vmax or between P0 and a/P0. However, there was a suggestion of an inverse relationship between a/P0 and Vmax, the effect being to reduce, somewhat, the impact of differences in Vmax on peak power. In searching for the causes of variation in peak power of fibres of the same type, it appears likely that there are two factors, one that affects P0 and another that leads to variation in both Vmax and a/P0.
ANTIMIROV AND MOSSES'S REWRITE SYSTEM REVISITED
Authors: ALMEIDA MARCO , MOREIRA NELMA , REIS ROGÉRIO
Published: July 2009

Antimirov and Mosses proposed a rewrite system for deciding the equivalence of two (extended) regular expressions. They argued that this method could lead to a better average-case algorithm than those based on the comparison of the equivalent minimal deterministic finite automata. In this paper we present a functional approach to that method, prove its correctness, and give some experimental comparative results. Besides an improved functional version of Antimirov and Mosses's algorithm, we present an alternative one using partial derivatives. Our preliminary results lead to the conclusion that, indeed, these methods are feasible and, most of the time, faster than the classical methods.
COMPOSED BISIMULATION FOR TREE AUTOMATA
Authors: ABDULLA PAROSH AZIZ , BOUAJJANI AHMED , HOLÍK LUKÁŠ , KAATI LISA , VOJNAR TOMÁŠ
Published: July 2009

We address the problem of reducing the size of (nondeterministic, bottom-up) tree automata (TA) using suitable, language-preserving equivalences on the states of the automata. In particular, we propose the so-called composed bisimulation equivalence as a new language preserving equivalence. A composed bisimulation equivalence is defined in terms of two different relations, namely the upward and downward bisimulation equivalence. We provide simple and efficient algorithms for computing these relations. The notion of composed bisimulation equivalence is motivated by an attempt to obtain an equivalence that can provide better reductions than what currently known bisimulation-based approaches can offer, but which is not significantly more difficult to compute (and hence stays below the computational requirements of simulation-based reductions). The experimental results we present in the paper show that our composed bisimulation equivalence meets such requirements, and hence provides users of TA with a finer way to resolve the trade-off between the available degree of reduction and its cost.
ASPECTS OF PERSISTENT COMPUTATIONS
Authors: HEMPEL HARALD , KIMMRITZ MADLEN
Published: July 2009

In this paper we formally define the notion of persistent Turing machines to model interactive computations. We compare the power of persistent Turing machines with respect to computing functions and relations and accepting sets with their classical counterparts. It turns out that the model of persistent computations leads to new characterizations of known function and language classes as well as to classes that have no classical counterpart.
ADIABATICITY OF THE DARK STATE IN A NONLINEAR ATOM-TRIMER CONVERSION SYSTEM
Authors: MENG SHAO-YING , FU LI-BIN , LIU JIE
Published: July 2009

We investigate the adiabaticity of the dark state in a nonlinear atom-trimer conversion system in a stimulated Raman adiabatic passage (STIRAP). We find that, in the absence of the nonlinear collisions, the adiabatic condition for this nonlinear system only depends on the Rabi-frequency of the dimer-trimer coupling optical field, which is different from traditional STIRAP processes. In the presence of the nonlinear collisions, the adiabatic condition also relies on the atom-dimer coupling Rabi frequency. However, its influence is really small. Moreover, we propose a more feasible two-photon STIRAP scheme that has better adiabaticity and hence could yield higher atom-trimer conversion efficiency.
THE DYNAMICS OF A CHANGING RANGE GENETIC ALGORITHM UNDER STABILIZING SELECTION
Authors: AMIRJANOV ADIL
Published: July 2009

The formalism is presented for modeling of a genetic algorithm (GA) with an adjustment of a search space size. The formalism for modeling of GA with an adjustment of a search space size assumes that the environment and the population form a unique system. In this paper, the formalism is applied to a problem which exhibits an interesting dynamics reminiscent of stabilizing selection in population biology. The equations of motion was derived that expressed the macroscopic statistical properties of population after reproductive genetic operators and an adjustment of a search space size in terms of those prior to the operation. Predictions of the theory are compared with experiments and are shown to predict the average fitness and the variance fitness of the final population accurately.
INTANGIBLE DETERMINANTS OF MARKET VALUE IN THE NEW ECONOMY: A DYNAMIC PANEL DATA ANALYSIS OF THE INDIAN SOFTWARE INDUSTRY
Authors: DE SUPRIYO
Published: July 2009

Intangible assets like human capital and organization capital have driven the success of India's software industry. This article analyzes the impact of intangible assets on the market value of Indian software firms using a dynamic panel data model. Measures of tangible and intangible assets are constructed using firm-level panel data. The estimation technique uses system generalized method of moments (GMM) and minimum distance estimation (MDE). This methodology accounts for unobserved firm heterogeneity, endogenous explanatory variables and persistent variables. The results conclusively show that intangible assets have a significant impact on market values of Indian software firms.
FRACTURE MECHANICS IN PERFORATED DOMAINS: A VARIATIONAL MODEL FOR BRITTLE POROUS MEDIA
Authors: FOCARDI MATTEO , GELLI M. S. , PONSIGLIONE M.
Published: July 2009

This paper deals with fracture mechanics in periodically perforated domains. Our aim is to provide a variational model for brittle porous media in the case of anti-planar elasticity.

Given the perforated domain Ωε ⊂ ℝN (ε being an internal scale representing the size of the periodically distributed perforations), we will consider a total energy of the type [Formula: see text] Here u is in SBV(Ωε) (the space of special functions of bounded variation), Su is the set of discontinuities of u, which is identified with a macroscopic crack in the porous medium Ωε, and [Formula: see text] stands for the (N - 1)-Hausdorff measure of the crack Su.

We study the asymptotic behavior of the functionals [Formula: see text] in terms of Γ-convergence as ε → 0. As a first (nontrivial) step we show that the domain of any limit functional is SBV(Ω) despite the degeneracies introduced by the perforations. Then we provide explicit formula for the bulk and surface energy densities of the Γ-limit, representing in our model the effective elastic and brittle properties of the porous medium, respectively.
Increased basal level of Akt-dependent insulin signaling may be responsible for the development of insulin resistance
Authors: Liu Hui-Yu , Hong Tao , Wen Ge-Bo , Han Jianmin , Zuo Degen , Liu Zhenqi , Cao Wenhong
Published: July 2009

A majority of subjects with insulin resistance and hyperinsulinemia can maintain their blood glucose levels normal for the whole life presumably through protein kinase B (Akt)-dependent insulin signaling. In this study, we found that the basal Akt phosphorylation level was increased in liver and gastrocnemius of mice under the high-fat diet (HFD). Levels of mitochondrial DNA and expression of some mitochondrion-associated genes were decreased by the HFD primarily in liver. Triglyceride content was increased in both liver and gastrocnemius by the HFD. Oxidative stress was induced by the HFD in both liver and gastrocnemius. Insulin sensitivity was decreased by the HFD. All of these changes were largely or completely reversed by treatment of animals with the phosphatidylinositol 3-kinase inhibitor LY-294002 during the time when animals usually do not eat. Consequently, the overall insulin sensitivity was increased by treatment with LY-294002. Together, our results indicate that increased basal Akt-dependent insulin signaling suppresses mitochondrial production, increases ectopic fat accumulation, induces oxidative stress, and desensitizes insulin signaling in subjects with insulin resistance and hyperinsulinemia.
Incidence and Risk of Cytomegalovirus Infection during Pregnancy in an Urban Area of Northern Italy
Authors: De Paschale Massimo , Agrappi Carlo , Manco Maria Teresa , Paganini Alessia , Clerici Pierangelo
Published: July 2009

The fetal consequences of CMV infection make it one of the most serious infections contracted during pregnancy, but the scientific community is divided over the proposed implementation of preventive screening for anti-CMV antibodies. The aim of this study was to assess the incidence and risk of infection during pregnancy in 2817 women who underwent anti-CMV IgG and IgM antibody screening during the period 2005–2007. The prevalence of anti-CMV IgG antibodies was 68.3% (95% CI: 66.6–70.0); the seroconversion rate in the 892 seronegative women was 0.32%; the results of IgG avidity testing revealed an cumulative incidence of 1.4% (95% CI: 0.97–1.83), density incidence of 0.8% (as cases/pregnant woman-trimester) (95% CI: 0.47–1.13), and a risk of infection of 0.5% (95% CI: 0.24–0.76). The screening identified 13 cases of primary infection (84.6% of which occurred in the first trimester of pregnancy). The possibility to identify these cases and consequently to plan appropriate interventions, supports the use of screening during pregnancy, especially in the first trimester when the risk of infection is greater.
Nonnegativity Preservation under Singular Values Perturbation
Authors: Montaño Emedin , Salas Mario , Soto Ricardo L.
Published: July 2009

We study how singular values and singular vectors of a matrix A change, under matrix perturbations of the form and , p ≠ q, where α ∈ ℝ, A is an m × n positive matrix with singular values σ1 ≥ σ2 ≥ ⋯≥σr > 0, r = min {m, n}, and uj, vk,  j = 1, …, m; k = 1, …, n, are the left and right singular vectors,
respectively. In particular we give conditions under which this kind of
perturbations preserve nonnegativity and certain matrix structures.
Diabetes Insipidus as a Complication of Wegener's Granulomatosis and Its Treatment with Biologic Agents
Authors: Cunnington Joanna Rosalind , Jois Ramesh , Zammit Ivan , Scott David , Isaacs John
Published: July 2009

Wegener's granulomatosis of the pituitary gland resulting in diabetes insipidus is a rare complication of the disease. Standard treatment for Wegener's granulomatosis involves a combination of prednisolone and cylophosphamide, however biologic agents are now being used in refractory cases. We report three cases of patients with diabetes insipidus as a complication of Wegener's granulomatosis who were treated with biologic agents. All three cases showed clinical response to treatment with biologic agents including rituximab and alemtuzumab and two cases demonstrated improvement in pituitary gland abnormalities by MRI. Clinicians should be aware that diabetes insipidus can present as a complication of Wegener's granulomatosis and that biologic therapies may be effective in refractory cases.
On the Creation of a Stable Drop‐Like Static Meniscus, Appropriate for the Growth of a Single Crystal Tube with Prior Specified Inner and Outer Radii
Authors: Balint Stefan , Balint Agneta M.
Published: July 2009

A theoretical procedure for the creation of a stable drop‐like static meniscus, appropriate for the growth of a single crystal tube, with a priori specified inner and outer radius, is presented. The method locates the controllable part p of the pressure difference across the free surface. It consists in a set of calculus, which leads to the determination of the melt column height (between the horizontal crucible melt level and the shaper top level) in function of the pressure of the gas flow (introduced in the furnace for release the heat) in order to obtain the desired meniscus. The procedure is presented in general and is numerically illustrated for InSb tubes. The novelty is the algorithm for the exact determination of p, which has to be used, the determination of the melt column height, and the evaluation of the effect of shaper radii. The setting of the thermal conditions, which assure that for the obtained static meniscus the solidification conditions are satisfied at the “right” places, is not considered here.
Clinical Significance of Epigenetic Inactivation of hMLH1 and BRCA1 in Tunisian Patients with Invasive Breast Carcinoma
Authors: Karray-Chouayekh Sondes , Trifa Fatma , Khabir Abdelmajid , Boujelbane Nouredine , Sellami-Boudawara Tahia , Daoud Jamel , Frikha Mounir , Gargouri Ali , Mokdad-Gargouri Raja
Published: July 2009

Aberrant hypermethylation of gene promoter regions is one of the mechanisms for inactivation of tumour suppressor genes in many human cancers including breast carcinoma. In the current study, we aimed to assess by MSP, the methylation pattern of two cancer‐related genes involved in DNA repair: hMLH1 (mutL homolog 1, colon cancer, nonpolyposis type 2 (E. coli) and BRCA1 (breast cancer 1, early onset) in 78 primary breast cancers from Tunisian patients. The methylation frequencies were 24.36% for hMLH1 and 46% for BRCA1. BRCA1 methylation correlated with age at diagnosis (P = .015) and 5‐years disease free survival (P = .016) while hMLH1 methylation was more frequent in larger tumors (P = .002) and in presence of distant metastasis (P = .004). Furthermore, methylation of hMLH1 significantly correlated with high level of P53 expression (P = .006) and with overall survival (P = .015) suggesting that silencing of hMLH1 through aberrant promoter methylation could be used as a poor prognosis indicator in breast cancer.
Design and Fabrication of Slotted Multimode Interference Devices for Chemical and Biological Sensing
Authors: Mayeh M. , Viegas J. , Srinivasan P. , Marques P. , Santos J. L. , Johnson E. G. , Farahi F.
Published: July 2009

We present optical sensors based on slotted multimode interference waveguides. The sensor can be tuned to highest sensitivity in the refractive index ranges necessary to detect protein‐based molecules or other water‐soluble chemical or biological materials. The material of choice is low‐loss silicon oxynitride (SiON) which is highly stable to the reactivity with biological agents and processing chemicals. Sensors made with this technology are suited to high volume manufacturing.
Effects of Condylar Elastic Properties to Temporomandibular Joint Stress
Authors: Zhang Min , Ono Takahiro , Chen Yongjin , Lv Xin , Wu Shun , Song Hong , Zhao Ruini , Wang Yibing
Published: July 2009

Mandibular condyle plays an important role in the growth and reconstruction of the temporomandibular joint (TMJ). We aimed to obtain orthotropic elastic parameters of the condyle using a continuous‐wave ultrasonic technique and to observe the effects of condylar elastic parameters on stress distribution of the TMJ using finite element analysis (FEA). Using the ultrasonic technique, all nine elastic parameters were obtained, which showed that the mandibular condyle was orthotropic. With the condyle defined as orthotropic, the occlusal stress was transferred fluently and uniformly from the mandible to the TMJ. The stress distribution in the isotropic model showed stepped variation among different anatomical structures with higher stress values in the cartilage and condyle than in the orthotropic model. We conclude that anisotropy has subtle yet significant effects on stress distribution of the TMJ and could improve the reality of simulations.
Kuri: A Simulator of Ecological Genetics for Tree Populations
Authors: Alle Benn R. , Furtado-Alle Lupe , Gondro Cedric , Magalhães João Carlos M.
Published: July 2009

This paper presents Kuri, a software package developed to simulate the temporal and spatial dynamics of genetic variability in populations and multispecies communities of trees, as well as their interactions with environmental factors. A conceptual model using agents inspired on Echo models is used to define the environment, the hierarchical structures, and the low-level rules of the system. At the individual agent (tree) level a genetic algorithm is used to model the genotypic structure and the genetic processes, from a small set of simple rules, complex higher-order population, and environmental interactions emerge. The program was written in Delphi for the Windows environment, and was designed to be used for educational and research purposes.
Fourier Approximation for Integral Equations on the Real Line
Authors: Hashemiparast S. M. , Fallahgoul H.
Published: July 2009

Based on Guass quadradure method a class of integral equations having unknown periodic solution on the real line is investigated, by using Fourier series expansion for the solution of the integral equation and applying a process for changing the interval to the finite interval (−1; 1), the Chebychev weights become appropriate and examples indicate the high
accuracy and very good approximation to the solution of the integral.
Analysis of Nonlinear Dynamics for Abrupt Change of Interphase Structure in Liquid‐Liquid Mass Transfer
Authors: Zhang DongXiang , Sun Min , Li Jing
Published: July 2009

As a liquid‐liquid system is far from equilibrium state, the phase thickness is variable when mass transfer process with chemical reaction occurs in interphase zone, and a dispersible transitional layer called the interphase dispersed zone (IDZ) is formed. The IZD model composed of thermodynamically instable O/W or W/O microemulsion has reasonably explained enormous experimental phenomena in nonlinear mass transfer. To forecast the possible parameter ranges of IDZ process and abrupt change of liquid‐liquid mass transfer rate, the dynamic characteristics of a molecular diffusion model are considered in this paper. We applied the bifurcation theory of planar dynamical system, Laplace transform, and maple software to investigate the model, and obtain different phase portraits of the system in different regions. The results obtained will play an important directive role in the study of IDZ model.
Non‐Boussinesq Integral Model for Horizontal Turbulent Buoyant Round Jets
Authors: Xiao J. , Travis J.R. , Breitung W.
Published: July 2009

Horizontal buoyant jet is a fundamental flow regime for hydrogen safety analysis in power industry. The purpose of this study is to develop a fast non‐Boussinesq engineering model the horizontal buoyant round jets. Verification of this integral model is established with available experimental data and comparisons over a large range of density variations with the CFD codes GASFLOW. The model has proved to be an efficient engineering tool for predicting horizontal strongly buoyant round jets.
Human Hepatocellular Carcinoma Tumor–derived Endothelial Cells Manifest Increased Angiogenesis Capability and Drug Resistance Compared with Normal Endothelial Cells
Authors: Xiong Yu-Quan , Sun Hui-Chuan , Zhang Wei , Zhu Xiao-Dong , Zhuang Peng-Yuan , Zhang Ju-Bo , Wang Lu , Wu Wei-zhong , Qin Lun-Xiu , Tang Zhao-You
Published: July 2009

Purpose: Increasing evidence indicates that tumor-derived endothelial cells (TEC) possess a distinct and unique phenotype compared with endothelial cells (NEC) from adjacent normal tissue and may be able to acquire resistance to drugs. The aim of this study was to investigate the angiogenesis activity and response to drug treatment of TECs and NECs derived from human hepatocellular carcinoma (HCC).

Experimental Design: TECs or NECs were isolated from HCC or adjacent normal liver tissue using anti-CD105 antibody coupled to magnetic beads. The phenotypic and functional properties of endothelial cells were characterized by testing the expression of CD105, CD31, CD144, vascular endothelial growth factor receptor-1, vascular endothelial growth factor receptor-2, and von Willebrand factor, and the ability of DiI-Ac-LDL-uptake and tube formations. CD105+ TECs were compared with CD105+ NECs and human umbilical vein endothelial cells (HUVEC) by examining their ability to proliferate, motility, ability to adhere to tumor cells, response to tumor conditioned medium, and reactions to the chemotherapy drugs Adriamycin and 5-fluorouracil and the antiangiogenic drug sorafenib.

Results: Compared with CD105+ NECs and HUVECs, CD105+ TECs showed increased apoptosis resistance and motility and proangiogenic properties. Meanwhile, CD105+ TECs had a greater ability to adhere to tumor cells and survive in the tumor environment. Moreover, CD105+ TECs acquired more resistance to Adriamycin, 5-fluorouracil, and sorafenib than CD105+ NECs and HUVECs.

Conclusions: TECs possessed enhanced angiogenic activity and resistance to chemotherapeutic drugs and an angiogenesis inhibitor, and may provide a better tool for studying tumor angiogenesis and antiangiogenesis drugs in HCC.