bluuebunny/crossref_metadata_2025 huggingface dataset:
Serotonin in Affective Control
Authors: Dayan Peter , Huys Quentin J.M.
Published: June 2009

Serotonin is a neuromodulator that is extensively entangled in fundamental aspects of brain function and behavior. We present a computational view of its involvement in the control of appetitively and aversively motivated actions. We first describe a range of its effects in invertebrates, endowing specific structurally fixed networks with plasticity at multiple spatial and temporal scales. We then consider its rather widespread distribution in the mammalian brain. We argue that this is associated with a more unified representational and functional role in aversive processing that is amenable to computational analyses with the kinds of reinforcement learning techniques that have helped elucidate dopamine's role in appetitive behavior. Finally, we suggest that it is only a partial reflection of dopamine because of essential asymmetries between the natural statistics of rewards and punishments.
Using Diffusion Imaging to Study Human Connectional Anatomy
Authors: Johansen-Berg Heidi , Rushworth Matthew F.S.
Published: June 2009

Diffusion imaging can be used to estimate the routes taken by fiber pathways connecting different regions of the living brain. This approach has already supplied novel insights into in vivo human brain anatomy. For example, by detecting where connection patterns change, one can define anatomical borders between cortical regions or subcortical nuclei in the living human brain for the first time. Because diffusion tractography is a relatively new technique, however, it is important to assess its validity critically. We discuss the degree to which diffusion tractography meets the requirements of a technique to assess structural connectivity and how its results compare to those from the gold-standard tract tracing methods in nonhuman animals. We conclude that although tractography offers novel opportunities it also raises significant challenges to be addressed by further validation studies to define precisely the limitations and scope of this exciting new technique.
Establishment of Axon-Dendrite Polarity in Developing Neurons
Authors: Barnes Anthony P. , Polleux Franck
Published: June 2009

Neurons are among the most highly polarized cell types in the body, and the polarization of axon and dendrites underlies the ability of neurons to integrate and transmit information in the brain. Significant progress has been made in the identification of the cellular and molecular mechanisms underlying the establishment of neuronal polarity using primarily in vitro approaches such as dissociated culture of rodent hippocampal and cortical neurons. This model has led to the predominant view suggesting that neuronal polarization is specified largely by stochastic, asymmetric activation of intracellular signaling pathways. Recent evidence shows that extracellular cues can play an instructive role during neuronal polarization in vitro and in vivo. In this review, we synthesize the recent data supporting an integrative model whereby extracellular cues orchestrate the intracellular signaling underlying the initial break of neuronal symmetry leading to axon-dendrite polarization.
Impaired ATP turnover and ADP supply depress cardiac mitochondrial respiration and elevate superoxide in nonfailing spontaneously hypertensive rat hearts
Authors: Hickey Anthony J. R. , Chai Chau C. , Choong Soon Y. , de Freitas Costa Silvana , Skea Gretchen L. , Phillips Anthony R. J. , Cooper Garth J. S.
Published: June 2009

Although most attention has been focused on mitochondrial ATP production and transfer in failing hearts, less has been focused on the nonfailing hypertensive heart. Here, energetic complications are less obvious, yet they may provide insight into disease ontogeny. We studied hearts from 12-mo-old spontaneously hypertensive rats (SHR) relative to normotensive Wistar-Kyoto (WKY) rats. The ex vivo working-heart model of SHR showed reduced compliance and impaired responses to increasing preloads. High-resolution respirometry showed higher state 3 (with excess ADP) respiration in SHR left ventricle fibers with complex I substrates and maximal uncoupled respiration with complex I + complex II substrates. Respiration with ATP was depressed 15% in SHR fibers relative to WKY fibers, suggesting impaired ATP hydrolysis. This finding was consistent with a 50% depression of actomyosin ATPase activities. Superoxide production from SHR fibers was similar to that from WKY fibers respiring with ADP; however, it was increased by 15% with ATP. In addition, the apparent Km for ADP was 54% higher for SHR fibers, and assays conducted after ex vivo work showed a 28% depression of complex I in SHR, but not WKY, fibers. Transmission electron microscopy showed similar mitochondrial volumes but a decrease in the number of cristae in SHR mitochondria. Tissue lipid peroxidation was also 15% greater in SHR left ventricle. Overall, these data suggest that although cardiac mitochondria from nonfailing SHR hearts function marginally better than those from WKY hearts, they show dysfunction after intense work. Impaired ATP turnover in hard-working SHR hearts may starve cardiac mitochondria of ADP and elevate superoxide.
Metformin improves postprandial glucose homeostasis in rainbow trout fed dietary carbohydrates: a link with the induction of hepatic lipogenic capacities?
Authors: Panserat S. , Skiba-Cassy S. , Seiliez I. , Lansard M. , Plagnes-Juan E. , Vachot C. , Aguirre P. , Larroquet L. , Chavernac G. , Medale F. , Corraze G. , Kaushik S. , Moon T. W.
Published: June 2009

Carnivorous fish are poor users of dietary carbohydrates and are considered to be glucose intolerant. In this context, we have tested, for the first time in rainbow trout, metformin, a common anti-diabetic drug, known to modify muscle and liver metabolism and to control hyperglycemia in mammals. In the present study, juvenile trout were fed with very high levels of carbohydrates (30% of the diet) for this species during 10 days followed by feeding with pellets supplemented with metformin (0.25% of the diet) for three additional days. Dietary metformin led to a significant reduction in postprandial glycemia in trout, demonstrating unambiguously the hypoglycemic effect of this drug. No effect of metformin was detected on mRNA levels for glucose transporter type 4 (GLUT4), or enzymes involved in glycolysis, mitochondrial energy metabolism, or on glycogen level in the white muscle. Expected inhibition of hepatic gluconeogenic (glucose-6-phosphatase, fructose-1,6-bisphosphatase, and phospho enolpyruvate carboxykinase) mRNA levels was not found, showing instead paradoxically higher mRNA levels for these genes after drug treatment. Finally, metformin treatment was associated with higher mRNA levels and activities for lipogenic enzymes (fatty acid synthase and glucose-6-phosphate dehydrogenase). Overall, this study strongly supports that the induction of hepatic lipogenesis by dietary glucose may permit a more efficient control of postprandial glycemia in carnivorous fish fed with high carbohydrate diets.
Comparative effects of oral and intraduodenal glucose on blood pressure, heart rate, and splanchnic blood flow in healthy older subjects
Authors: Gentilcore Diana , Nair Nivasinee S. , Vanis Lora , Rayner Christopher K. , Meyer James H. , Hausken Trygve , Horowitz Michael , Jones Karen L.
Published: June 2009

Postprandial hypotension occurs frequently, particularly in the elderly. The magnitude of the fall in blood pressure (BP) and rise in heart rate (HR) in response to enteral glucose are greater when gastric emptying (GE) or small intestinal infusion are more rapid. Meal ingestion is associated with an increase in splanchnic blood flow. In contrast, gastric distension may attenuate the postprandial fall in BP. The aims of this study were to evaluate, in older subjects, the comparative effects of intraduodenal glucose infusion, at a rate similar to GE of oral glucose, on BP, HR, superior mesenteric artery (SMA) flow, and blood glucose. Eight healthy subjects (5 men, 3 women, age 66–75 yr) were studied on two occasions. On day 1, each subject ingested 300 ml of water containing 75 g glucose. GE was quantified by three-dimensional ultrasonography between time t = 0–120 min, and the rate of emptying (kcal/min) was calculated. On day 2, glucose was infused intraduodenally at the same rate as that on day 1. On both days, BP, HR, SMA flow, and blood glucose were measured. The mean GE of oral glucose was 1.3 ± 0.1 kcal/min. Systolic BP ( P < 0.01), SMA flow ( P < 0.05), and blood glucose ( P < 0.01) were greater and HR less ( P < 0.01) after oral, compared with intraduodenal, glucose. There were comparable falls in diastolic BP during the study days ( P < 0.01 for both). We conclude that the magnitude of the fall in systolic BP and rise in HR are less after oral, compared with intraduodenal, glucose, presumably reflecting the “protective” effect of gastric distension.
Functional overload in ground squirrel plantaris muscle fails to induce myosin isoform shifts
Authors: Choi Hyung , Selpides Pocholo-Jose I. , Nowell Megan M. , Rourke Bryan C.
Published: June 2009

We performed 2 wk of mechanical overload by synergist ablation on plantaris muscles from a small rodent hibernator, Spermophilus lateralis. While this muscle displays prominent myosin heavy-chain (MyHC) isoform shifts during hibernation, sensitivity to mechanical loading as a stimulus for muscle mass and isoform plasticity has not been demonstrated. Squirrel muscles, whether during hibernation or not, potentially are less sensitive to mechanical unloading, but we hypothesized that increased loading would produce the typical mammalian response of greater plantaris mass and MyHC shifts. Mechanical overload produced a 50% increase in muscle mass but, surprisingly, no changes in MyHC isoform protein or mRNA expression, despite previously observed fast-to-slow MyHC isoform switching during hibernation. Citrate synthase enzyme activity, as well as mRNA expression of creatine kinase and the muscle growth factor myostatin, were all unchanged. The mRNA expression of critical muscle atrophy genes decreased by 50% during hypertrophy, including ubiquitin ligases MuRF1 and MAFbx, and the related transcription factor FOXO-1a. Insulin-like growth factor (IGF-1) and hypoxia-inducible factor (HIF-1α) mRNA expression was elevated by 400% and 150%. Fast-to-slow MyHC isoform shifts appear unnecessary to support the increased recruitment of the plantaris muscle, shifts which are seen in other rodent models. Our results are consistent with muscular activity during interbout arousals as a potential mechanism to preserve muscle mass, but illustrate the primary importance of other seasonal factors besides patterns of muscle activation which must act in concert to alter MyHC isoforms and muscle fiber type during hibernation.
Hsp27 inhibits sublethal, Src-mediated renal epithelial cell injury
Authors: Havasi Andrea , Wang Zhiyong , Gall Jonathan M. , Spaderna Max , Suri Vikram , Canlas Ellery , Martin Jody L. , Schwartz John H. , Borkan Steven C.
Published: June 2009

Disruption of cell contact sites in renal epithelial cells contributes to organ dysfunction after ischemia. We hypothesized that heat shock protein 27 (Hsp27), a known cytoprotectant protein, preserves cell architecture and cell contact site function during ischemic stress. To test this hypothesis, renal epithelial cells were subjected to transient ATP depletion, an in vitro model of ischemia-reperfusion injury. Compared with control, selective Hsp27 overexpression significantly preserved cell-cell junction function during metabolic stress as evidenced by reduced stress-mediated redistribution of the adherens junction protein E-cadherin, higher transepithelial electrical resistance, and lower unidirectional flux of lucifer yellow. Hsp27 overexpression also preserved paxillin staining within focal adhesion complexes and significantly decreased cell detachment during stress. Surprisingly, Hsp27, an F-actin-capping protein, only minimally reduced stress induced actin cytoskeleton collapse. In contrast to Hsp27 overexpression, siRNA-mediated knockdown had the opposite effect on these parameters. Since ischemia activates c-Src, a tyrosine kinase that disrupts both cell-cell and cell-substrate interactions, the relationship between Hsp27 and c-Src was examined. Although Hsp27 and c-Src did not coimmunoprecipitate and Hsp27 overexpression failed to inhibit whole cell c-Src activation during injury, manipulation of Hsp27 altered active c-Src accumulation at cell contact sites. Specifically, Hsp27 overexpression reduced, whereas Hsp27 knockdown increased active p-416Src detected at contact sites in intact cells as well as in a purified cell membrane fraction. Together, this evidence shows that Hsp27 overexpression prevents sublethal REC injury at cell contact sites possibly by a c-Src-dependent mechanism. Further exploration of the biochemical link between Hsp27 and c-Src could yield therapeutic interventions for ameliorating ischemic renal cell injury and organ dysfunction.
Deep pulmonary lymphatics in immature lungs
Authors: Dickie Renée , Cormack Meredith , Semmler-Behnke Manuela , Kreyling Wolfgang G. , Tsuda Akira
Published: June 2009

Recently, we found that the translocation of inhaled nanoparticles from the air space to secondary organs is age dependent and substantially greater in neonates than in adults ( J Respir Crit Care Med 177: A48, 2008). One reason for this difference might be age-dependent differences in alveolar barrier integrity. Because the neonate lung is undergoing morphogenetic and fluid balance changes, we hypothesize that the alveolar barrier of developing lungs is more easily compromised and susceptible to foreign material influx than that of adult lungs. On the basis of these hypotheses, we predict that the postnatally developing lung is also more likely to allow the translocation of some materials from the air space to the lymphatic lumens. To test this idea, we intratracheally instilled methyl methacrylate into immature and adult lungs and compared lymphatic filling between these two age groups. Scanning electron microscopy of the resultant corrosion casts revealed peribronchial saccular and conduit lymphatic architecture. Deep pulmonary lymphatic casts were present on the majority (58.5%) of airways in immature lungs, but lymphatic casting in adult lungs, as anticipated, was much more infrequent (21.6%). Thus the neonate lung appears to be more susceptible than the adult lung to the passage of instilled methyl methacrylate from the air space into the lymphatics. We speculate that this could imply greater probability of translocation of other materials, such as nanoparticles, from the immature lung as well.
How Reliable is the Pattern Adaptation Technique? A Modeling Study
Authors: Hegdé Jay
Published: June 2009

Upon prolonged viewing of a sinusoidal grating, the visual system is selectively desensitized to the spatial frequency of the grating, while the sensitivity to other spatial frequencies remains largely unaffected. This technique, known as pattern adaptation, has been so central to the psychophysical study of the mechanisms of spatial vision that it is sometimes referred to as the “psychologist's microelectrode.” While this approach implicitly assumes that the adaptation behavior of the system is diagnostic of the corresponding underlying neural mechanisms, this assumption has never been explicitly tested. We tested this assumption using adaptation bandwidth, or the range of spatial frequencies affected by adaptation, as a representative measure of adaptation. We constructed an intentionally simple neuronal ensemble model of spatial frequency processing and examined the extent to which the adaptation bandwidth at the system level reflected the bandwidth at the neuronal level. We find that the adaptation bandwidth could vary widely even when all spatial frequency tuning parameters were held constant. Conversely, different spatial frequency tuning parameters were able to elicit similar adaptation bandwidths from the neuronal ensemble. Thus, the tuning properties of the underlying units did not reliably reflect the adaptation bandwidth at the system level, and vice versa. Furthermore, depending on the noisiness of adaptation at the neural level, the same neuronal ensemble was able to produce selective or nonselective adaptation at the system level, indicating that a lack of selective adaptation at the system level cannot be taken to mean a lack of tuned mechanisms at the neural level. Together, our results indicate that pattern adaptation cannot be used to reliably estimate the tuning properties of the underlying units, and imply, more generally, that pattern adaptation is not a reliable tool for studying the neural mechanisms of pattern analysis.
Seasonal Plasticity of Auditory Saccular Sensitivity in the Vocal Plainfin Midshipman Fish,Porichthys notatus
Authors: Sisneros Joseph A.
Published: June 2009

The plainfin midshipman fish, Porichthys notatus, is a seasonally breeding species of marine teleost fish that generates acoustic signals for intraspecific social and reproductive-related communication. Female midshipman use the inner ear saccule as the main acoustic endorgan for hearing to detect and locate vocalizing males that produce multiharmonic advertisement calls during the breeding season. Previous work showed that the frequency sensitivity of midshipman auditory saccular afferents changed seasonally with female reproductive state such that summer reproductive females became better suited than winter nonreproductive females to encode the dominant higher harmonics of the male advertisement calls. The focus of this study was to test the hypothesis that seasonal reproductive-dependent changes in saccular afferent tuning is paralleled by similar changes in saccular sensitivity at the level of the hair-cell receptor. Here, I examined the evoked response properties of midshipman saccular hair cells from winter nonreproductive and summer reproductive females to determine if reproductive state affects the frequency response and threshold of the saccule to behaviorally relevant single tone stimuli. Saccular potentials were recorded from populations of hair cells in vivo while sound was presented by an underwater speaker. Results indicate that saccular hair cells from reproductive females had thresholds that were ∼8 to 13 dB lower than nonreproductive females across a broad range of frequencies that included the dominant higher harmonic components and the fundamental frequency of the male's advertisement call. These seasonal-reproductive-dependent changes in thresholds varied differentially across the three (rostral, middle, and caudal) regions of the saccule. Such reproductive-dependent changes in saccule sensitivity may represent an adaptive plasticity of the midshipman auditory sense to enhance mate detection, recognition, and localization during the breeding season.
Serotonergic Modulation of the Trigeminocardiac Reflex Neurotransmission to Cardiac Vagal Neurons in the Nucleus Ambiguus
Authors: Gorini C. , Jameson H. S. , Mendelowitz D.
Published: June 2009

Stimulation of the trigeminal nerve evokes a dramatic decrease in heart rate and blood pressure, and this reflex has generally been termed the trigeminocardiac reflex. A subset of the trigeminocardiac reflex is the diving reflex in which the nasal mucosa is stimulated with water or air-borne chemical irritants. Activation of the diving reflex evokes a pronounced bradycardia, mediated by increased parasympathetic cardiac activity, and is the most powerful autonomic reflex. However, exaggeration of this protective response could be detrimental and has been implicated in Sudden Infant Death Syndrome (SIDS). Despite the importance and strength of the trigeminocardiac reflex, there is little information about the cellular mechanisms and brain stem pathways that constitute this reflex. To address these issues, stimulation of trigeminal afferent fibers and the evoked excitatory postsynaptic currents were recorded in cardiac vagal neurons (CVNs) in an in vitro brain stem slice preparation. This synaptic pathway is robust and activation of the trigeminal pathway often evoked action potentials in CVNs. Application of the serotonin (5-HT) reuptake inhibitor citalopram significantly enhanced these responses. Consistent with the hypothesis this pathway is endogenously modulated by 5-HT receptors the 5-HT1Areceptor antagonist, WAY 100635 inhibited, whereas the 5-HT2A/Creceptor antagonist, ketanserin facilitated the excitatory neurotransmission to CVNs. The 5-HT1Areceptor agonist 8-hydroxy-2-(dipropylamino)tetralin hydrobromide increased, whereas the 5-HT2receptor agonist, α-methylserotonin maleate salt inhibited this reflex pathway. These results indicate stimulation of trigeminal fibers evokes a powerful excitatory and polysynaptic pathway to CVNs, and this pathway is endogenously modulated and differentially enhanced and depressed, by 5-HT1Aand 5-HT2receptors, respectively.
GABA Shapes Selectivity for the Rate and Direction of Frequency-Modulated Sweeps in the Auditory Cortex
Authors: Razak Khaleel A. , Fuzessery Zoltan M.
Published: June 2009

In the pallid bat auditory cortex and inferior colliculus (IC), the majority of neurons tuned in the echolocation range is selective for the direction and rate of frequency-modulated (FM) sweeps used in echolocation. Such selectivity is shaped mainly by spectrotemporal asymmetries in sideband inhibition. An early-arriving, low-frequency inhibition (LFI) shapes direction selectivity. A delayed, high-frequency inhibition (HFI) shapes rate selectivity for downward sweeps. Using iontophoretic blockade of GABAa receptors, we show that cortical FM sweep selectivity is at least partially shaped locally. GABAa receptor antagonists, bicuculline or gabazine, reduced or eliminated direction and rate selectivity in ∼50% of neurons. Intracortical GABA shapes FM sweep selectivity by either creating the underlying sideband inhibition or by advancing the arrival time of inhibition relative to excitation. Given that FM sweep selectivity and asymmetries in sideband inhibition are already present in the IC, these data suggest a refinement or recreation of similar response properties at the cortical level.
Multijoint Reflex Responses to Constant-Velocity Volitional Movements of the Stroke Elbow
Authors: Sangani Samir G. , Starsky Andrew J. , McGuire John R. , Schmit Brian D.
Published: June 2009

Multijoint reflex coupling could impact the voluntary control of functional arm movements in people post stroke. The multijoint responses to active-assist, constant-velocity movements of the elbow joint were measured in 14 individuals post stroke and 9 neurologically intact controls. Resulting responses in the stroke group illustrated a change in the reflex coupling of the elbow and shoulder muscles compared with passive perturbations of the spastic elbow. Voluntary effort during constant-velocity elbow extension resulted in reflex shoulder abduction, differing from the reflex coupling observed between the elbow flexors and shoulder adductors observed during passive elbow extension. These results suggest that post stroke, voluntary drive alters reflex coupling of the elbow and shoulder. Flexion of the elbow during active-assist also resulted in reflex coupling. Shoulder abduction torque decreased with constant-velocity flexion of the elbow; however, no net adduction was observed at the end of the perturbation. Shoulder flexion/extension and internal/external rotation torque responses demonstrated similar modulations to imposed active-assist perturbations of the elbow in subjects post stroke. Responses were absent during passive perturbations of the control elbow; however, shoulder torque modulations were observed during constant-velocity, active-assist tasks. The active-assist response patterns in controls were similar to stroke subjects during the extension task but opposite during flexion of the elbow. This study provides evidence of a neural coupling between elbow and shoulder muscles and a modulation of this coupling during voluntary drive of the spastic arm.
A Generalization of Kannan's Fixed Point Theorem
Authors: Enjouji Yusuke , Nakanishi Masato , Suzuki Tomonari
Published: June 2009

In order to observe the condition of Kannan mappings, we prove a generalization of Kannan's fixed point theorem. Our theorem involves constants and we obtain the best constants to ensure a fixed point.
snRNP: Rich Nuclear Bodies inHyacinthus orientalisL. Microspores and Developing Pollen Cells
Authors: Zienkiewicz K. , Bednarska E.
Published: June 2009

The aim of the present work was the characterization of nuclear bodies in the microspore and developing pollen cells ofHyacinthus orientalisL.. The combination of Ag-NOR, immunofluorescence and immunogold techniques was used in this study. The obtained results showed the presence of highly agyrophylic extranucleolar bodies in microspore and developing pollen cells, which were finally identified as Cajal bodies. In all cases, a strong accumulation of snRNP-indicating molecules including TMG cap, Sm proteins and U2 snRNA, was observed in the examined nuclear bodies. In contrast to their number the size of the identified structures did not change significantly during pollen development. In the microspore and the vegetative cell of pollen grains CBs were more numerous than in the generative cell. At later stages of pollen development, a drastic decrease in CB number was observed and, just before anthesis, a complete lack of these structures was indicated in both pollen nuclei. On the basis of these results, as well as our previous studies, we postulate a strong relationship between Cajal body numbers and the levels of RNA synthesis and splicing machinery elements in microspore and developing pollen cells.
A First Implementation of an Advanced 3D Interface to Control and Supervise UAV (Uninhabited Aerial Vehicles) Missions
Authors: Crescenzio Francesca De , Miranda Giovanni , Persiani Franco , Bombardi Tiziano
Published: June 2009

Recent analyses on the uninhabited aerial vehicle (UAV) accidents revealed that several kinds of human-system control problems occur in current UAV missions. Therefore, a design of the man–machine interface that allows for an efficient and effective interaction between the operator and the remote vehicle becomes one of the challenges in the development of more reliable UAVs. This paper presents a first implementation of an advanced interface for UAV ground control station based on a touch screen, a 3D virtual display, and an audio feedback message generator. The touch screen is used to send high level commands to the vehicle, the 3D virtual display provides a stereoscopic and augmented visualization of the complex scenario in which the vehicle operates, and the audio feedback message generator informs the operator about any change in operational scenario. The hardware/software architecture of the interface also includes a planning algorithm and a generic vehicle model. The interface has been tested by simulating several UAV missions. The results have shown that the interface requires an adequate level of workload to command the vehicle and allows the operator to build a good level of awareness of the state of the vehicle under his or her control, as well as of the environment in which it operates.
Presence Related Formal Aspects of Hedonic Valence in Mood Management: An Investigation of the Impact of Mediated Experiences on Induced Aggressive Mood
Authors: Schweizer Karin
Published: June 2009

This paper lays out presence related formal aspects of media offerings suited to evoke mood management (Zillmann, 1988). Zillmann proposes that apart from other dimensions, the mood-impacting characteristics of media stimuli vary with the hedonic valence referring to the content (see also Knobloch-Westerwick, 2006). In this contribution, it is claimed that not only does the hedonic value vary with content, but also with formal characteristics of stimuli that refer to different types of media. In contrast to other investigations on mood management, these investigations focus on the reduction of aversive moods when exposed to certain media offerings. The investigations do not focus on the measurement of selected stimuli arrangements in terms of time and intensity.

To test this hypothesis, the current paper presents the results of two studies in which 66 participants were presented with film sequences in order to induce aggressive moods. In the first experiment, which served as a treatment check, it was shown that aggressive moods could be reduced more with televised exposures than with a waiting period. In a second experiment, participants having partaken in the experimental induction of aggressive moods were allocated to different experimental conditions that are classified according to formal aspects of hedonic valence: a television exposure condition, an internet surfing condition, and a chat condition. These activities can be numerically classified according to three axes, (i) the amount of sensory information, (ii) the extent of possible interactions, and (iii) the synchrony between sender and recipient. The resulting categorizations of certain media offerings (television exposure: 3, internet surfing: 9–11, and chatting: 8) simultaneously represent certain aspects of the concept of presence. Results show that the induced aggressive moods can be mostly reduced by the treatment (media offerings) with the highest number allocated (internet surfing). Moreover, the findings show an overall decrease of aggressive moods according to the increasing number from television to internet.
Comparison of the Levels of Presence and Anxiety in an Acrophobic Environment Viewed via HMD or CAVE
Authors: Juan M. Carmen , Pérez David
Published: June 2009

People who suffer from acrophobia fear any situation that involves heights. Several virtual reality systems have been presented to treat this problem. This paper presents a comparison study of the levels of presence and anxiety in an acrophobic environment that is viewed using a computer automatic virtual environment (CAVE) and a head-mounted display (HMD). In this environment, the floor fell away and the walls rose up. To determine whether either of the two visualization systems induced a greater sense of presence/anxiety in non-phobic users, an experiment comparing the two visualization systems was carried out. Twenty-five participants took part in this study. After using each visualization system (HMD or CAVE), the participants were asked to fill out an adapted Slater et al. questionnaire (Slater, Usoh, & Steed, 1994), and a Student t test was applied to the data obtained. The CAVE induces a high level of presence in users. The mean score was 5.01 (where 7 is the maximum value), which was higher than the score obtained using the HMD which was 3.59. The Student t test indicates that there are significant statistical differences. The level of anxiety was also examined at different times during the experiment. The results indicate that both visualization systems provoke anxiety, but that the CAVE provokes more anxiety than the HMD. The animation in which the floor falls away is the one that provoked the most anxiety. The results from the correlation between the anxiety and the level of presence at the three times indicated a significant correlation between the two measures.
Description of Action in the Narratives of Euripidean and Sophoclean Tragedy
Authors: Poe Joe Park
Published: June 2009

Drama and narrative share basic constituents, such as a chronological series of actions, their agents, and a setting in time and place. Narrative, moreover, often makes use of dialogue, while dramatic dialogue is hardly conceivable without narrative. Recognition of this kinship has encouraged the notion that narrative and dialogue are naturally complementary, so that when a story is told in tragic dialogue, for instance, the dramatic illusion is maintained unaffected. This essay asserts to the contrary that, just as certain kinds of narrative are not hospitable to dialogue, certain dramatic narratives—messenger speeches in particular—do not fit well in the dialogues in which they are embedded. In support of this assertion the study attempts to examine the way in which the narratives in Sophoclean and Euripidean dialogue describe action. Assuming that dramatic narrative seeks to approximate, at least in some degree, what van Dijk calls “natural narrative”—that occurring in everyday conversation—which mentions only those actions and events that are “strictly relevant”, the study finds that in fact most narratives in tragic dialogue are sparing of extraneous detail. There is, however, a group of narratives which with some frequency make 'irrelevant' multiple references to single actions and events. Most of the Euripidean narratives spoken by anonymous messengers and three in Sophoclean tragedy belong to this group, as well as five narratives spoken by named characters, four of which closely resemble messenger speeches in form and function.
Demosthenes, Parody and the Frogs
Authors: Pontani Filippomaria
Published: June 2009

The present paper attempts to show a textual contact between Demosthenes and Old Comedy in

Or.

18.267 and 19.245: discussion of the two passages (the latter one plays an important role in the frame of the ancient rhetorical theory of parody) will be followed by the suggestion of a deeper link between a section of the

False Embassy

and Aristophanes'

Frogs

, in terms not only of verbal echoes but also of common rhetorical motifs and strategy.
Propertius 3.1.27
Authors: Dominicy Marc
Published: June 2009

The paradosis of Propertius 3.1.27:

Idaeum Simoenta Iouis (cunabula parui)

is either lacunose (N) or nonsensical (all other manuscripts). Gustav Wolff 's celebrated. . .

cum prole Scamandro

runs against objections in terms of paleographical verisimilitude, intertextual relevance, and conformity with elegiac diction. This paper provides arguments in favor of. . .

ruisse in pabula parta

, which echoes two Homeric passages (

Il

. 5.773-7, 12.19-22) while pointing, intertextually, to Lucretius and the archaic forms of epic poetry. Paleographically,

ruisse in pabula parta

can easily have yielded

Iouis cunabula parua

. Moreover, Petrarch's use of

cunabula parua

in 1342 suggests that his (lost) copy of Propertius, and the (now incomplete) manuscript A from which it was made in 1333, bore

parua

. If

parui

is a later correction, the standard theory, according to which the manuscript tradition of Propertius divides into the N and A families, is vindicated against the alternative theory recently put forward by James L. Butrica and Stephen J. Heyworth.
Crossing the Rubicon. A Historiographical Study
Authors: Rondholz Anke
Published: June 2009

This paper contains a typological comparison of the extant accounts of Caesar's crossing of the Rubicon (Velleius Paterculus, Lucan, Plutarch, Suetonius, Appian, Orosius) and highlights interrelationships among the various accounts as well as patterns and

topoi

in the Rubicon myth. This episode has been dramatized by five of the authors as a point of transition from peace to war, although Caesar has set himself at fault much earlier by maneuvering to resign his command. Common motifs are the speed with which Caesar proceeds, his hesitation and pondering the consequences, and the connection of the crossing with a supernatural element. Caesar's nocturnal wanderings in Suetonius can be explained as a misinterpretation of Plutarch's account; the scene about the apparition with the reed pipe plays with generic markers to express the beginning of war. Finally, a conclusion can be drawn about Asinius Pollio as the common source. As a child of the Late Republic he might have been interested in mitigating his representation of the Rubicon scene by having Caesar hesitate, ponder the consequences, be under divine influence and act in self-defense, features that were exploited by his successors and turned into

topoi

of the Rubicon myth.
"They Ain't Making Elites Like They Used To": The Never Ending Trouble with Democratic Elitism
Authors: Borchert Jens
Published: June 2009

This article identifies three central tenets of democratic elitism as developed by various authors. It then traces the fate of these ideas within democratic theory. Surprisingly, I find almost universal, if unacknowledged, acceptance of democratic elitism's principles in contemporary theories of democracy. In the public, however, there is still a strong yearning for a democracy that is closer to the ideal and more open to public participation. This is reflected in public criticisms of "detached" professional politicians. I argue that a conceptual solution to the tension between the state of democratic theory and the public's expectations may ironically be provided by one strand within the theory of democratic elitism, namely Robert Dahl's theory of polyarchy.
Democratic Elitism – Conflict and Consensus
Authors: Engelstad Fredrik
Published: June 2009

Classical elite theory stressed tensions between elites and democracy, whereas modern studies of elites take democracy as a point of departure – to a large extent under the heading of democratic elitism. This article discusses two strands of elite studies in a democracy perspective, one stressing elite conflict, the other focusing on elite consensus. As points of departure for empirical analysis both strands are valuable, but when linked to democratic theory they are insufficient. It is necessary to view elites in light of constitutional features that regulate their relationship with the state. Moreover, the public sphere must be taken into account as a constitutive element of democracy and as an arena for communication between elite groups and between them and citizenries.
Elites and Democracy's Illusions
Authors: Higley John
Published: June 2009

This article argues that ideologies, which elites utilize for political justification and mobilization, are always misleading guides to what can be accomplished politically. After reviewing how socialism preoccupied and misled elites during the "short" twentieth century, I examine how the ideology of democracy, in which Western elites today have unquestioned faith, conceals a range of fundamental sociopolitical changes and distorts the implications of various major events. The fixation of elites on democracy's illusions is leading – in some respects has already led – to disaster.
Associated Rivals: Antagonism and Cooperation in the German Political Elite
Authors: Best Heinrich
Published: June 2009

This article explores the failures and achievements of democratic elitism in Germany. I first outline the conditions in which concepts of leader democracy and democratic elitism were set forth by Max Weber and Joseph Schumpeter during the first half of the twentieth century. I then argue that democratic elitism can usefully be reformulated in terms of principal-agent theory and William Sumner's theory of antagonistic cooperation. I present empirical findings from a study of elite conflict and consensus in re-unified Germany that are consistent with these theories, and I suggest that democratic elitism should incorporate both.
Democratic Elitism and Western Political Thought
Authors: Higley John
Published: June 2009

Many political thinkers have viewed democratic elitism as closing a democratic road they believe is or should be open-ended. Their view of democratic possibilities reflects the auspicious circumstances of Western societies during the past several centuries and especially since World War II. However, it involves a conflation of liberal and democratic values. I examine why and how this has occurred, and I argue that liberal and democratic values must be more clearly separated in today's dangerous world. In step with Schumpeter, democracy must be regarded as a method or instrumental value that in some but by no means all circumstances promotes the ultimate liberal value of actively individualistic free people.
Image, Text and Observatio: The Codex Kentmanus
Authors: Kusukawa Sachiko
Published: June 2009

This paper examines the inter-relationship between image, text and object in the Codex Kentmanus, which is one of the earliest records of the plants in the botanical garden at Padua, studied by Johannes Kentmann (1518-77). The manuscript shows that “observation” for Kentmann involved a gradual process of assimilating knowledge from other physicians, apothecaries, and books in order to make the plants which were originally encountered at a specific time and place into a more generalised object of study for learned physicians.
Low-Frequency Variability of Temperature in the Vicinity of the Equatorial Pacific Thermocline in SODA: Role of Equatorial Wave Dynamics and ENSO Asymmetry
Authors: Dewitte B. , Thual S. , Yeh S-W. , An S-I. , Moon B-K. , Giese B. S.
Published: June 2009

The Simple Ocean Data Assimilation (SODA) reanalysis (1958–2001) is used to investigate the decadal variability in the equatorial thermocline in the Pacific. Whereas the thermocline depth exhibits weak variation at decadal time scales, the temperature change in the vicinity of the thermocline in the western Pacific is significant and has a vertical scale of ∼150 m. Based on a modal decomposition of the model variability, it is shown that such temperature change can be interpreted to a large extent as vertical displacements of the isotherms associated with the Kelvin and first meridional Rossby waves of the first three baroclinic modes. This indicates that decadal change at the subsurface in the warm pool region may be forced by the winds, consistent with the results of a multimode linear model simulation. The decadal mode of vertical temperature can be described by the first two dominant statistical modes (EOFs): the first mode is associated with changes in the slope of the thermocline (swallowing in the western-central Pacific and deepening in the eastern Pacific), representative of the 1976/77 climate shift and ahead of the ENSO modulation; and the second mode corresponds to a basinwide uplift of the thermocline and behind the ENSO modulation. It is further shown that the subsurface temperature in the warm pool region is negatively skewed, which results from the ENSO asymmetry. The results are consistent with the hypothesis of change in mean state resulting from the residual effect of the asymmetric ENSO variability.
Nonstationary Impacts of the Southern Annular Mode on Southern Hemisphere Climate
Authors: Silvestri Gabriel , Vera Carolina
Published: June 2009

The temporal stability of the southern annular mode (SAM) impacts on Southern Hemisphere climate during austral spring is analyzed. Results show changes in the typical hemispheric circulation pattern associated with SAM, particularly over South America and Australia, between the 1960s–70s and 1980s–90s. In the first decades, the SAM positive phase is associated with an anomalous anticyclonic circulation developed in the southwestern subtropical Atlantic that enhances moisture advection and promotes precipitation increase over southeastern South America (SESA). On the other hand, during the last decades the anticyclonic anomaly induced by the SAM’s positive phase covers most of southern South America and the adjacent Atlantic, producing weakened moisture convergence and decreased precipitation over SESA as well as positive temperature anomaly advection over southern South America.

Some stations in the Australia–New Zealand sector and Africa exhibit significant correlations between the SAM and precipitation anomalies in both or one of the subperiods, but they do not characterize a consistent area in which the SAM signal can be certainly determined. Significant changes of SAM influence on temperature anomalies on multidecadal time scales are observed elsewhere. Particularly over the Australia–New Zealand sector, significant positive correlations during the first decades become insignificant or even negative in the later period, whereas changes of opposite sign occur in the Antarctic Peninsula between both subperiods.
Modal Decay in the Australia–Antarctic Basin
Authors: Weijer Wilbert , Gille Sarah T. , Vivier Frédéric
Published: June 2009

The barotropic intraseasonal variability in the Australia–Antarctic Basin (AAB) is studied in terms of the excitation and decay of topographically trapped barotropic modes. The main objective is to reconcile two widely differing estimates of the decay rate of sea surface height (SSH) anomalies in the AAB that are assumed to be related to barotropic modes. First, an empirical orthogonal function (EOF) analysis is applied to almost 15 years of altimeter data. The analysis suggests that several modes are involved in the variability of the AAB, each related to distinct areas with (almost) closed contours of potential vorticity. Second, the dominant normal modes of the AAB are determined in a barotropic shallow-water (SW) model. These stationary modes are confined by the closed contours of potential vorticity that surround the eastern AAB, and the crest of the Southeast Indian Ridge. For reasonable values of horizontal eddy viscosity and bottom friction, their decay time scale is on the order of several weeks. Third, the SW model is forced with realistic winds and integrated for several years. Projection of the modal velocity patterns onto the output fields shows that the barotropic modes are indeed excited in the model, and that they decay slowly on the frictional 𝒪(3 weeks) time scale. However, the SSH anomalies in the modal areas display rapid 𝒪(4 days) decay. Additional analysis shows that this rapid decay reflects the adjustment of unbalanced flow components through the emission of Rossby waves. Resonant excitation of the dominant free modes accounts for about 20% of the SSH variability in the forced-model run. Other mechanisms are suggested to explain the region of high SSH variability in the AAB.
Mixed Layer Cooling in Mesoscale Oceanic Eddies during Hurricanes Katrina and Rita
Authors: Jaimes Benjamin , Shay Lynn K.
Published: June 2009

During favorable atmospheric conditions, Hurricanes Katrina and Rita deepened to category 5 over the Loop Current’s (LC) bulge associated with an amplifying warm core eddy. Both hurricanes subsequently weakened to category 3 after passing over a cold core eddy (CCE) prior to making landfall. Reduced (increased) oceanic mixed layer (OML) cooling of ∼1°C (4.5°C) was observed over the LC (CCE) where the storms rapidly deepened (weakened). Data acquired during and subsequent to the passage of both hurricanes indicate that the modulated velocity response in these geostrophic features was responsible for the contrasts in the upper-ocean cooling levels. For similar wind forcing, the OML velocity response was about 2 times larger inside the CCE that interacted with Katrina than in the LC region affected by Rita, depending on the prestorm OML thickness. Hurricane-induced upwelling and vertical mixing were increased (reduced) in the CCE (LC). Less wind-driven kinetic energy was available to increase vertical shears for entrainment cooling in the LC, as the OML current response was weaker and energy was largely radiated into the thermocline. Estimates of downward vertical radiation of near-inertial wave energies were significantly stronger in the LC (12.1 × 10−2 W m−2) than in the CCE (1.8 × 10−2 W m−2). Katrina and Rita winds provided O(1010) W to the global internal wave power. The vertical mixing induced by both storms was confined to the surface water mass. From a broader perspective, models must capture oceanic features to reproduce the differentiated hurricane-induced OML cooling to improve hurricane intensity forecasting.