bluuebunny/crossref_metadata_2025 huggingface dataset:
Feeding Ecology of Juvenile (Age-0) Silver Hake (Merluccius bilinearis) on the Scotian Shelf
Authors: Koeller P. A. , Coates-Markle L. , Neilson J. D.
Published: May 2008

Feeding patterns of juvenile silver hake (Merluccius bilinearis) (length range 19–90 mm) captured by midwater trawl were compared between seasons (fall and winter), years (1980 and 1981), fish lengths, and depth and time of capture. Prey selection shifted gradually with increasing fish length, from copepods at the smaller size ranges, to amphipods, euphausiids and silver hake at the larger sizes. An abrupt shift in the feeding pattern occurred as larvae metamorphosed into juveniles, but there were no similar "critical" changes during the juvenile phase itself. Cannibalism of juveniles by juveniles was pronounced and could be an important factor influencing year-class strength. Silver hake juveniles did not prey on the larvae or juveniles of other fish species, nor did they compete with them for available food, mainly because the juveniles of other species were rare during the period of greatest silver hake abundance in the pelagic zone. Evidence from abundance surveys and the feeding study suggests that increased size-at-date at the early juvenile stage, possibly due to more favourable growth and feeding conditions, resulted in increased survival. Differences in feeding patterns among fish in different size categories, and captured at different depths and times generally substantiate diet migration patterns inferred from previous vertical distribution experiments.
Estimation of Size-Specific Molting Probabilities in Adult Decapod Crustaceans Based on Postmolt Indicator Data
Authors: Mohr Michael S. , Hankin David G.
Published: May 2008

For crustaceans that exhibit a well-defined molting season, postmolt indicator methods may be used to classify a sample of animals collected after the molting season into those that have molted and those that have failed to molt. This binary classification of a sample may be used to estimate size-specific molting probabilities. We derive maximum likelihood estimators for these molting probabilities, and for the variances of estimated molting probabilities, based on such postmolt indicator data. Estimators assume that the premolt–postmolt relation is linear with an additive and normally distributed error term of constant variance and, in their simplest form, assume that the ratio (Ri) of size-specific survival probabilities through the molting season for molting as compared with nonmolting individuals is known. For the more likely situation in which only a plausible range for Ri is specifiable, an estimation procedure is proposed which minimizes the maximum possible error (mean square error) of the molting probability estimator over this range. We illustrate application of estimators using shell condition data collected from the northern California population of adult female Dungeness crabs (Cancer magister). Estimated annual molting probabilities for adult female Dungeness crabs were greater than 0.90 for crabs less than 135 mm carapace width, but then declined rapidly until they were near zero for crabs exceeding 160 mm carapace width. This conclusion was not substantively affected by choices of a survival ratio ranging from 0.4 to 1.0.
Analysis of Weddell seal (Leptonychotes weddelli) vocalizations using underwater playbacks
Authors: Thomas Jeanette A. , Zinnel Kathlean C. , Ferm Lisa M.
Published: May 2008

The Weddell seal (Leptonychotes weddelli) in McMurdo Sound, Antarctica, has a large repertoire of underwater vocalizations (12 calls with 34 types) ranging from short pulses to long frequency-modulated sweeps. Individual vocalizations were projected under water to seals at breeding colonies to investigate their functions. Responses were affected by the time of day, length of experiment, and composition of the colony. Specific vocalizations were given in response to particular playbacks. The duration of responses changed for different types of playbacks, but the number of elements per series did not. Only functions for vocalizations associated with breeding were assigned.
Size, organic composition, and energy content of Leach's storm-petrel (Oceanodroma leucorhoa) eggs with reference to position in the precocial–altricial spectrum and breeding ecology
Authors: Montevecchi W. A. , Kirkham I. R. , Roby D. D. , Brink K. L.
Published: May 2008

Leach s storm-petrel eggs are very similar in composition to those of birds whose young develop precocially. In comparison with altricial species, eggs are relatively large (22% of adult mass), contain large yolks (41% of fresh egg contents) and have high yolk to albumen ratios. As in other precocial species, water content was low, making up 70% of the whole egg, 87% of the albumen, and 50% of the yolk, but accounted for much intraspecific variation in egg mass. The low water content is notable in view of the petrel's long incubation period, though low porosity of the eggshell and high humidity in the nest burrow must help the embryo conserve water. High lipid levels in the yolk (27%) are similar to those of precocial birds. Fresh yolk and albumen each contained 14% protein. About 80% (55.3 ± 2.5 kJ) of the total energy in the egg (60.7 ± 3.8 kJ) was contained in the yolk. The energy density of wet egg contents (7.27 ± 0.48 kJ/g) falls in the range of precocial birds. The egg's high energy content can be explained in terms of the maintenance requirements of the embryo during the long incubation period and the precocity of the hatchling. On the basis of standard metabolic rate estimates and interspecific comparisons, it does not appear to be energetically costly for a female to produce an egg. Single egg clutches and absence of relaying following egg loss suggest that the pelagic feeding ecology of Leach's storm-petrel imposes severe constraints on parental feeding rates and meal size, which effectively limit viable brood size to one.
Seasonal variations in the swimming performance of perch (Perca fluviatilis L.) measured with the rotatory-flow technique
Authors: Sandström Olof
Published: May 2008

Swimming in fish is composed of both propulsive and maneuvering components. In this paper evidence is presented for a seasonal rhythm in the maneuvering capacity of a temperate area fish, the perch (Perca fluviatilis L.). The rotatory-flow technique, measuring the ability of the fish to maintain its posture in a rotating water current, was used in the study. Tests on animals kept under constant conditions in the laboratory revealed that this seasonal rhythm was generated by an endogenous oscillation. Based on these observations and existing knowledge about locomotor activity and body constituent rhythms, a winter strategy in perch is proposed that implies an endogenously regulated change in behaviors leading to an economic use of stored energy.
Demography, growth, and food of western painted turtles, Chrysemys picta bellii (Gray), from southern Saskatchewan
Authors: MacCulloch Ross D. , Secoy D. M.
Published: May 2008

Western painted turtles from populations in the northern portion of their range attained greater sizes, had more rapid growth despite a shorter growing season, and appeared to mature at a larger size than turtles from farther south. Mean clutch size was 19.8, with no evidence of production of two clutches. Examination of stomach contents showed that the turtles were mainly carnivorous, even in areas of abundant vegetation. The carnivorous diet may account for the large sizes, large clutches, and rapid growth of the turtles and may permit C. picta to maintain populations farther north than other North American turtle species.
Field tests of competitive interference for space among temperate-zone rodents
Authors: Morris Douglas W.
Published: May 2008

Within-habitat distributions of common rodent species in two temperate-zone small mammal faunas were analyzed by a series of interaction tests to evaluate the hypothesis that the distribution and abundance of these animals is determined by competitive interference for space. In the Rocky Mountains of Alberta, Peromyscus maniculatus and Clethrionomys gapperi were independently distributed and there was no consistent relationship between the densities of the two species over a broad range of habitats. At Point Pelee National Park in Ontario, Peromyscus leucopus and Microtus pennsylvanicus distributions were also independent of one another, and again there was no relationship between the densities of these rodents across habitats. These field tests favour rejection of the hypothesis of competitive interference for space among temperate-zone small mammal species.
Functional differences of the proboscides of short- and long-tongued bees (Hymenoptera, Apoidea)
Authors: Harder Lawrence D.
Published: May 2008

Ingestion of liquids by a short-tongued bee (Andrena carlini), recorded cinematographically, involved repeated protraction and retraction of the prementum and coordinated lapping by the glossa while the maxillae remained motionless. The action of the proboscis of a long-tongued bee (Bombus pennsylvanicus) differs from this in that the prementum remains stationary. Differences in proboscidial mechanics are associated with morphological differences, which together affect the ingestion rates observed for five species of each of the two types of bees. Although small bees of both morphological types ingested nectar at equivalent rates, large long-tongued bees were more efficient than short-tongued bees of similar body size. The relative abundance of large bees in long-tongued families in two faunas suggests that the comparative efficiencies of these two morphological conditions has had evolutionary consequences.
Growth and development of Taenia crassiceps (Cestoda) in the small intestine and peritoneal cavity of mice following oral infection
Authors: Kroeze W. K. , Freeman R. S.
Published: May 2008

The growth and development of metacestodes of Taenia crassiceps in mice was studied after experimental oral infection with cysticerci. Soon after infection, the holdfasts of most cysticerci evaginated in the stomach, and usually the bladders detached before the worms reached the small intestine. From the intestine, some worms entered the peritoneal cavity within the first 24 h. Others remained in the gut lumen up to 16 days. Very rarely were the rostellar hooks everted on evaginated holdfasts in the intestine and only slightly more commonly on holdfasts in the peritoneal cavity. Some worms in the small intestine and some in the peritoneal cavity segmented and developed genital primordia, although they did not become sexually mature. A few worms in the peritoneal cavity resumed asexual reproduction by budding, either from bladder tissue that had been pulled into the cavity by the penetrating worms, or from solid (nonbladder) tissue.
Influence of the semiaquatic habit in determining burrow structure of the star-nosed mole (Condylura cristata)
Authors: Hickman Graham C.
Published: May 2008

Condylura cristata is unique from most talpids in being semiaquatic. This report investigates the effect of a water habitat on burrow structure and is the first description of completely excavated burrow systems of the star-nosed mole, representing reedbed and lakeside habitats. Major features of the burrow structure included lack of surface ridges and mounds, unplugged burrows, along the edge of water, lack of steep vertical shafts to lower levels, deep tunnels not confined to particular areas of burrow system, a single active nest chamber containing dead leaves and freshly chewed pieces of Typha, and absence of special chambers for food storage or defecation. In comparing the influence of aquatic habits on structure of the burrow with terrestrial (Scalopus aquaticus) and aquatic (Desmana moschata) species of Talpidae, the semiaquatic Condylura is intermediate in position.
The occurrence of coccidia (Eimeriidae) in epididymal semen of a wapiti (Cervus canadensis nelsoni)
Authors: Hrudka F. , Cawthorn R. J. , Haigh J. C.
Published: May 2008

Meronts, merozoites, oocysts, and unidentified stages of a new species of the family Eimeriidae (phylum Apicomplexa, class Sporozoasida) were found in the reproductive tract of one of four wapiti (Cervus canadensis nelsoni) bulls shot during the rut. The eimeriids were observed free in luminal content and in the epithelium of ductus epididymidis. They did not noticeably affect the morphological integrity of spermatozoa. It is suggested that the parasite may develop intraluminally, either in abortive sperm precursors or free in epididymal fluid; the latter is an optimal medium for sperm maturation and could also be conducive for development of parasites.
Infrared Radiation Spectrum of Acupuncture Point on Patients with Coronary Heart Disease
Authors: Shen Xueyong , Ding Guanghong , Deng Haiping , Wei Jianzi , Zhao Ling , Zhou Yu , Lao Lixing
Published: May 2008

The objective of this study was to compare the acupoint infrared radiation spectrums of patients and healthy volunteers to show whether those of coronary heart disease (CHD) patients carry distinctive pathological information. PHE201, using a highly sensitive infrared spectrum detection device applied to the acupoint Neiguan (PC6) and to a control point on 50 CHD patients and 47 healthy adults. A total of 73 wavelength spots were detected. The scanned wavelengths ranged from 1.5 μm to 16 μm, and the scanning spacing was 0.2 μm. The data were automatically recorded in the database of the device for statistical analysis. Infrared radiation intensities of 23 in the 73 detected wavelength spots significantly differed in the CHD patients' Neiguan as compared to those of the healthy subjects (from p = 0.048 to p = 0.002), while only 12 wavelength spots at a non-acupuncture control point showed significant differences. By the χ2 test, these differences between Neiguan and the non-acupuncture control point are statistically significant ( p = 0.033). At 2-2.5 μm, which is related to energy metabolism, the intensity at the CHD patients' Neiguan was significantly lower than that of the healthy adults (from p = 0.026 to p = 0.017). No difference was observed at the non-acupuncture control point (from p = 0.094 to p = 0.052). The data suggest that the changes of infrared spectrum at Neiguan in coronary heart disease patients may reflect the distinct pathological changes. This may be the result of hypoactive energy metabolism in the area of the acupoint.
Treatment of Menopausal Symptoms with Er-xian Decoction: A Systematic Review
Authors: Chen H. Y. , Cho William C. S. , Sze S. C. W. , Tong Y.
Published: May 2008

The purpose of this systemic review is to assess the efficacy of Er-xian decoction (EXD), a formula of Chinese medicine, in relieving menopausal symptoms. Seven databases were extensively retrieved. The Chinese electronic databases include VIP Information, CBMdisc, and CNKI. The English electronic databases include AMED, CINAHL, Cochrane Library, and MEDLINE. Randomized controlled trials using EXD as a main intervention were included in the study selection. The quality of studies was assessed by Jadad scale and the criteria referred in Cochrane reviewers' handbook. Two independent reviewers were responsible for data extraction and assessment. Discrepancies were rectified referring to the original articles. The efficacy of EXD treatment for menopausal symptoms was evaluated by meta-analysis. There were 154 articles retrieved according to the search strategy, 677 participants involved in the 5 studies that satisfied the selection criteria. Meta-analysis indicated that administration of EXD significantly relieved at least one menopausal symptom when compared to the control group at a 95% confidence interval ( p < 0.01). The curing effect of EXD with all symptoms relieved was significant as compared with the control groups ( p < 0.01). The results also indicated that the efficacy of EXD was better than the other non-menopausal hormone therapy ( p < 0.01), while there was no significant difference between the EXD and menopausal hormone therapy groups. The EXD is effective in treating menopausal symptoms. However, owing to the low quality of the investigated studies, more randomized controlled trials are needed before evidence-based recommendation regarding the effectiveness of EXD in the management of menopausal symptoms can be provided.
Inhibition of MITF and Tyrosinase by Paeonol-Stimulated JNK/SAPK to Reduction of Phosphorylated CREB
Authors: Bu Jin , Ma Peng-Cheng , Chen Zhi-Qiang , Zhou Wu-Qing , Fu You-Jun , Li Ling-Jun , Li Cheng-Rang
Published: May 2008

Tyrosinase and its transcriptional regulator microphthalmia-associated transcription factor (MITF) play critical roles in regulation of melanogenesis, and are required for environmental cues or agents in modulation of melanin synthesis. Identifying the signals regulating tyrosinase and MITF is crucial to understanding how pigmentation responds to extracellular stimuli. In this report, we discovered that paeonol down-regulated melanin production via decreasing MITF expression and consequent mRNA and protein levels of tyrosinase. We also found that paeonol reduced phosphorylation of a cAMP responsive element binding protein (phospho-CREB), which binds and activates MITF. A selective inhibitor of c-jun N-terminal or stress-activated protein kinases (JNK/SAPK)-SP600125 significantly reversed paeonol-induced down-regulation of melanogenesis. Inhibition of cAMP/PKA pathway intensified the hypopigmentation response to paeonol. These results identify a mechanism in which paeonol induces the down-regulation of melanogenesis through inhibition of CREB phosphorylation, leading to the expression reduction of MITF and subsequently tyrosinase. The key kinase mediating the effects of paeonol on melanogenesis in B16F10 cells is JNK/SAPK. Additionally, the cAMP/PKA pathway may take part in this process.
Interaction of Salvianolic Acids and Notoginsengnosides in Inhibition of ADP-Induced Platelet Aggregation
Authors: Yao Yan , Wu Wan-Ying , Liu Ai-Hua , Deng Shao-Sheng , Bi Kai-Shun , Liu Xuan , Guo De-An
Published: May 2008

Salvia miltiorrhiza and Panax notoginseng were both considered to be beneficial to cardiovascular diseases in traditional Chinese medicine and often used in combination. To examine the possible interaction between them, the effects of the active fractions of these two herbs, salvianolic acids (SA) and notoginsengnosides (NG), on platelet aggregation were checked respectively or in combination in vitro and in vivo. Both the platelet aggregation of platelet rich plasma (PRP) and washed platelet after ADP induction were checked. In vitro study showed that both SA and NG had an inhibitory effect on platelet aggregation. However, there is no synergistic effect of the combination of SA and NG in vitro. In vivo study showed that i.g. 550 mg/kg/day SA or NG for 5 days could significantly inhibit ADP-induced platelet aggregation of PRP. Moreover, combination of SA and NG at a ratio of 5:1 had a synergistic effect on platelet aggregation of PRP. The mechanism for the synergism of SA and NG in vivo was not clear. High performance liquid chromatography analysis of the plasma of rats received SA, NG or combination of SA and NG showed that co-administration of NG caused change in the plasma distribution profile of SA. The influence of combination on the absorption and/or metabolism of SA may be one of the reasons for the synergism of SA and NG in vivo.
Anticancer Activities and Mechanisms of Blumea balsamifera Extract in Hepatocellular Carcinoma Cells
Authors: Norikura Toshio , Kojima-Yuasa Akiko , Shimizu Miki , Huang Xuedan , Xu Shenghui , Kametani Saeda , Rho Sook-Nyung , Kennedy David Opare , Matsui-Yuasa Isao
Published: May 2008

Blumea balsamifera (also known as sambong), a medicinal plant, is known to improve physiological disorders such as rheumatism and hypertension. However, its anticancer activity has not been well elucidated. In this study, we found that Blumea balsamifera MeOH extract (BME) induced growth inhibitory activity in rat and human hepatocellular carcinoma cells (McA-RH7777, HepG2, respectively) without cytotoxicity as in with rat hepatocytes used as a normal cell model. BME induced cell cycle arrest at G1 phase via decreases in expression of cyclin-E and phosphorylation of retinoblastoma (Rb) protein in both dose- and time-dependent manners. Furthermore, BME reduced the level of a proliferation related ligand (APRIL) which stimulates tumor cell growth. The anti-proliferative effect of BME was improved slightly but significantly by the treatment with recombinant human APRIL. These findings suggest that BME may have a possible therapeutic potential in hepatoma cancer patients and the depletion of cellular APRIL may be one of the important mechanisms on the growth inhibitory effect of BME.
EVALUATING ENTREPRENEURSHIP PROGRAMMES – OBJECTIVES AND MEASUREMENT DILEMMAS
Authors: HAVNES PER-ANDERS , SKJEKKELAND LINE MARIE B
Published: May 2008

The manifestation of entrepreneurship is new business ventures that may be organised within or outside existing firms. Governments in all countries in the industrial world attempt to encourage entrepreneurship as an instrument to renew and strengthen their economy. Many of these governments evaluate their policies by monitoring results of the programmes.

This paper examines the evaluation of an ongoing entrepreneurial support programme in Norway. The evaluation of the programme demonstrates that inconsistent and ambiguous goals complicate the measurements that are required for the evaluation. Further complications arise from the fact that some goals are specified in quantitative, others in qualitative terms. Finally, the evaluation draws attention to the significance of the incubation period between cause and effect.

Such problems indicate that however precise quantitative measures appear to be when presented in statistical table or graphs, caution is necessary when the measurements are used to assess the effects of programmes and activities.
Functional Neuroanatomy of Meaning Acquisition from Context
Authors: Mestres-Missé Anna , Càmara Estela , Rodriguez-Fornells Antoni , Rotte Michael , Münte Thomas F.
Published: May 2008

An important issue in language learning is how new words are integrated in the brain representations that sustain language processing. To identify the brain regions involved in meaning acquisition and word learning, we conducted a functional magnetic resonance imaging study. Young participants were required to deduce the meaning of a novel word presented within increasingly constrained sentence contexts that were read silently during the scanning session. Inconsistent contexts were also presented in which no meaning could be assigned to the novel word. Participants showed meaning acquisition in the consistent but not in the inconsistent condition. A distributed brain network was identified comprising the left anterior inferior frontal gyrus (BA 45), the middle temporal gyrus (BA 21), the parahippocampal gyrus, and several subcortical structures (the thalamus and the striatum). Drawing on previous neuroimaging evidence, we tentatively identify the roles of these brain areas in the retrieval, selection, and encoding of the meaning.
Timing, Storage, and Comparison of Stimulus Duration Engage Discrete Anatomical Components of a Perceptual Timing Network
Authors: Coull Jennifer T. , Nazarian Bruno , Vidal Franck
Published: May 2008

The temporal discrimination paradigm requires subjects to compare the duration of a probe stimulus to that of a sample previously stored in working or long-term memory, thus providing an index of timing that is independent of a motor response. However, the estimation process itself comprises several component cognitive processes, including timing, storage, retrieval, and comparison of durations. Previous imaging studies have attempted to disentangle these components by simply measuring brain activity during early versus late scanning epochs. We aim to improve the temporal resolution and precision of this approach by using rapid event-related functional magnetic resonance imaging to time-lock the hemodynamic response to presentation of the sample and probe stimuli themselves. Compared to a control (color-estimation) task, which was matched in terms of difficulty, sustained attention, and motor preparation requirements, we found selective activation of the left putamen for the storage (“encoding”) of stimulus duration into working memory (WM). Moreover, increased putamen activity was linked to enhanced timing performance, suggesting that the level of putamen activity may modulate the depth of temporal encoding. Retrieval and comparison of stimulus duration in WM selectively activated the right superior temporal gyrus. Finally, the supplementary motor area was equally active during both sample and probe stages of the task, suggesting a fundamental role in timing the duration of a stimulus that is currently unfolding in time.
Neural Organization of Linguistic Short-term Memory is Sensory Modality–dependent: Evidence from Signed and Spoken Language
Authors: Pa Judy , Wilson Stephen M. , Pickell Herbert , Bellugi Ursula , Hickok Gregory
Published: May 2008

Despite decades of research, there is still disagreement regarding the nature of the information that is maintained in linguistic short-term memory (STM). Some authors argue for abstract phonological codes, whereas others argue for more general sensory traces. We assess these possibilities by investigating linguistic STM in two distinct sensory–motor modalities, spoken and signed language. Hearing bilingual participants (native in English and American Sign Language) performed equivalent STM tasks in both languages during functional magnetic resonance imaging. Distinct, sensory-specific activations were seen during the maintenance phase of the task for spoken versus signed language. These regions have been previously shown to respond to nonlinguistic sensory stimulation, suggesting that linguistic STM tasks recruit sensory-specific networks. However, maintenance-phase activations common to the two languages were also observed, implying some form of common process. We conclude that linguistic STM involves sensory-dependent neural networks, but suggest that sensory-independent neural networks may also exist.
Enhancement of Auditory-evoked Potentials in Musicians Reflects an Influence of Expertise but not Selective Attention
Authors: Baumann Simon , Meyer Martin , Jäncke Lutz
Published: May 2008

Instrumental tones and, in some instances, simple sine-wave tones were shown to evoke stronger auditory-evoked responses in musicians compared to nonmusicians. This effect was taken as an example for plasticity in the auditory cortex elicited by training. To date, however, it is unknown whether an enlarged cortical representation for (instrumental) tones or increased neuronal activity provoked by focused attention in musicians accounts for the reported difference. In an attempt to systematically investigate the influence of attention on the processing of simple sine wave and instrumental tones, we compared auditory-evoked potentials recorded from musicians and nonmusicians. During the electroencephalogram recording, the participants were involved in tasks requiring selective attention to specific sound features such as pitch or timbre. Our results demonstrate that the effect of selective attention on the auditory event-related potential (AEP) has a different time course and shows a different topography than the reproduced effect of music expertise at the N1 component or the previously demonstrated effect at the P2 component. N1 peak potentials were unaffected by attention modulation. These results indicate that the effect of music expertise, which was traced by current density mapping to the auditory cortex, is not primarily caused by selective attention, and it supports the view that increased AEPs on tones in musicians reflect an enlarged neuronal representation for specific sound features of these tones. However, independent from the N1–P2 complex, attention evoked an Nd-like negative component in musicians but not in nonmusicians, which suggests that plasticity also affects top–down processes.
Convergence of the Visual Field Split: Hemispheric Modeling of Face and Object Recognition
Authors: Hsiao Janet Hui-wen , Shieh Danke X. , Cottrell Garrison W.
Published: May 2008

Anatomical evidence shows that our visual field is initially split along the vertical midline and contralaterally projected to different hemispheres. It remains unclear at which processing stage the split information converges. In the current study, we applied the Double Filtering by Frequency (DFF) theory (Ivry & Robertson, 1998) to modeling the visual field split; the theory assumes a right-hemisphere/low-frequency bias. We compared three cognitive architectures with different timings of convergence and examined their cognitive plausibility to account for the left-side bias effect in face perception observed in human data. We show that the early convergence model failed to show the left-side bias effect. The modeling, hence, suggests that the convergence may take place at an intermediate or late stage, at least after information has been extracted/encoded separately in the two hemispheres, a fact that is often overlooked in computational modeling of cognitive processes. Comparative anatomical data suggest that this separate encoding process that results in differential frequency biases in the two hemispheres may be engaged from V1 up to the level of area V3a and V4v, and converge at least after the lateral occipital region. The left-side bias effect in our model was also observed in Greeble recognition; the modeling, hence, also provides testable predictions about whether the left-side bias effect may also be observed in (expertise-level) object recognition.
Applying Telepresence to Incident Management: The Virtual Incident Command Center
Authors: Gyorfi Julius S. , Buhrke Eric R. , Tarlton Mark A. , Lopez Juan M. , Valliath George T.
Published: May 2008

This paper describes an application of telepresence technology to the incident management domain. The system combines national guidelines for incident management with many aspects of collaborative virtual environments to enable effective communication between first responders in the field and remotely located command personnel. A brief overview of existing incident management systems is given, followed by a set of requirements for future systems. We then describe our virtual incident command center (VICC) prototype, explain how it addresses the requirements, and outline our future plans. Finally, we report feedback from ongoing demonstrations of the prototype system that supports our contention that VICC represents a unique solution to the incident management problem.
The Causes and Consequences of Presence: Considering the Influence of Violent Video Games on Presence and Aggression
Authors: Nowak Kristine L. , Krcmar Marina , Farrar Kirstie M.
Published: May 2008

The level of presence is likely to influence the effect of media violence. This project examines the causes and consequences of presence in the context of violent video game play. In a between subjects design, 227 participants were randomly assigned to play either a violent or a nonviolent video game. The results are consistent with what would be predicted by social learning theory and are consistent with previous presence research. Causal modeling analyses reveal two separate paths to presence: from individual differences and condition. The first path reveals that individual differences (previous game use and gender) predict presence. Those who frequently play video games reported higher levels of presence than those who play video games less frequently. Males play more games but felt less presence than women. The second path is related to perceived violence: those who perceived the game to be more violent felt more presence than those who perceived less violence in the game. Both of these paths were influenced by frustration with the game, which reduced presence. Those who felt more presence felt more hostility and were more verbally aggressive than those who felt lower levels of presence. Higher levels of presence led to increased physically aggressive intentions. Theoretical and practical implications are discussed.
Telepresence after Death
Authors: Lombard Matthew , Markaridian Selverian Melissa E.
Published: May 2008

This paper examines some of the increasingly sophisticated attempts by humans to evoke the presence of themselves or others after death and considers these efforts in the context of telepresence theory and research. Potential future research and ethical implications are also addressed.
A Fast Three-Dimensional Approximation for the Calculation of Surface Irradiance in Large-Eddy Simulation Models
Authors: Wapler Kathrin , Mayer Bernhard
Published: May 2008

Cloud-resolving models—in particular, large-eddy simulation (LES) models—are important tools to improve the understanding of cloud–radiation interactions. A method is presented for accurate, yet fast, three-dimensional calculation of surface shortwave irradiance within an LES model using the tilted independent column approximation with smoothing of the diffuse irradiance. The algorithm calculates a tilted optical thickness for each surface pixel that is then used as input to a one-dimensional radiative transfer code. In a sensitivity analysis, it is shown that this calculation can even be replaced by a simple precalculated lookup table that tabulates surface irradiance as a function of only solar zenith angle and cloud optical thickness. Because the vertical variability of the cloud is of little relevance for the surface irradiance, this approximation introduces little extra uncertainty. In a final step, surface irradiance is smoothed to account for horizontal photon transport between individual columns. The algorithm has been optimized for parallelization, which enhances its applicability in LES models. In this implementation, the total computational time of the LES model increased by only 3% relative to the reference run without radiation. Comparisons between the fast approximation and detailed three-dimensional radiative transfer calculations showed very good agreement for different cloud conditions and several solar zenith and azimuth angles, with a root-mean-square difference of 6%.
Formation of Jets by Baroclinic Turbulence
Authors: Farrell Brian F. , Ioannou Petros J.
Published: May 2008

Turbulent fluids are frequently observed to spontaneously self-organize into large spatial-scale jets; geophysical examples of this phenomenon include the Jovian banded winds and the earth’s polar-front jet. These relatively steady large-scale jets arise from and are maintained by the smaller spatial- and temporal-scale turbulence with which they coexist. Frequently these jets are found to be adjusted into marginally stable states that support large transient growth. In this work, a comprehensive theory for the interaction of jets with turbulence, stochastic structural stability theory (SSST), is applied to the two-layer baroclinic model with the object of elucidating the physical mechanism producing and maintaining baroclinic jets, understanding how jet amplitude, structure, and spacing is controlled, understanding the role of parameters such as the temperature gradient and static stability in determining jet structure, understanding the phenomenon of abrupt reorganization of jet structure as a function of parameter change, and understanding the general mechanism by which turbulent jets adjust to marginally stable states supporting large transient growth.

When the mean thermal forcing is weak so that the mean jet is stable in the absence of turbulence, jets emerge as an instability of the coupled system consisting of the mean jet dynamics and the ensemble mean eddy dynamics. Destabilization of this SSST coupled system occurs as a critical turbulence level is exceeded. At supercritical turbulence levels the unstable jet grows, at first exponentially, but eventually equilibrates nonlinearly into stable states of mutual adjustment between the mean flow and turbulence. The jet structure, amplitude, and spacing can be inferred from these equilibria.

With weak mean thermal forcing and weak but supercritical turbulence levels, the equilibrium jet structure is nearly barotropic. Under strong mean thermal forcing, so that the mean jet is unstable in the absence of turbulence, marginally stable highly nonnormal equilibria emerge that support high transient growth and produce power-law relations between, for example, heat flux and temperature gradient. The origin of this power-law behavior can be traced to the nonnormality of the adjusted states.

As the stochastic excitation, mean baroclinic forcing, or the static stability are changed, meridionally confined jets that are in equilibrium at a given meridional wavenumber abruptly reorganize to another meridional wavenumber at critical values of these parameters.

The equilibrium jets obtained with this theory are in remarkable agreement with equilibrium jets obtained in simulations of baroclinic turbulence, and the phenomenon of discontinuous reorganization of confined jets has important implications for storm-track reorganization and abrupt climate change.
Tropical Atlantic Variability Modes (1979–2002). Part II: Time-Evolving Atmospheric Circulation Related to SST-Forced Tropical Convection
Authors: García-Serrano Javier , Losada Teresa , Rodríguez-Fonseca Belén , Polo Irene
Published: May 2008

The ways in which deep convection over the tropical Atlantic affects the midlatitude climate variability through meridional circulation, planetary wave teleconnection, and wave–mean flow interaction is examined for the 1979–2002 period, by following the North Atlantic anomalous rainfall evolution from summer to late winter. In this way, the first two covariability modes between anomalous summer tropical Atlantic sea surface temperature (SST) and anomalous summer–late-winter precipitation over the North Atlantic basin are analyzed using the same methodology of extended maximum covariance analysis developed for Part I. This work updates the results given by other authors, whose studies are based on different datasets dating back to the 1950s. To this end, the Climate Prediction Center (CPC) Merged Analysis of Precipitation (CMAP) dataset, which includes measures over the ocean, is used to give a complete picture of the interannual rainfall patterns for the last decades.

The first mode, which accounts for more than 40% of the squared covariance fraction (SCF), involves SST anomalies related to the equatorial mode or Atlantic Niño. Its atmospheric response shows variations of the Atlantic Hadley and Ferrel circulations, reinforcing the direct and indirect circulation cells, respectively, displacements of the Atlantic Walker circulation, and the excitation of Rossby waves, which are trapped in the North African–Asian jet. The second mode, which accounts for 15% of the SCF, is associated with the summer horseshoe and winter tripole SST patterns. The related atmospheric circulation anomalies include direct thermal forcing (altering the local Hadley cell), perturbations in the ITCZ, and wavelike responses from the Caribbean region.

The method used in this work highlights the seasonal dependence of the modes, in contrast to previous work that neglects to take into account the month-to-month evolution of these modes. The results add new and valuable information to the understanding of these modes from the important period back to the 1980s.
An Improved Parameterization for Simulating Arctic Cloud Amount in the CCSM3 Climate Model
Authors: Vavrus Steve , Waliser Duane
Published: May 2008

A simple alternative parameterization for predicting cloud fraction in the Community Climate System Model, version 3 (CCSM3) global climate model is presented. This formula, dubbed “freeezedry,” is designed to alleviate the bias of excessive low clouds during polar winter by reducing the cloud amount under very dry conditions. During winter, freezedry decreases the low cloud amount over the coldest regions in high latitudes by over 50% locally and more than 30% averaged across the Arctic. The cloud reduction causes an Arctic-wide drop of 15 W m−2 in surface cloud radiative forcing (CRF) during winter and about a 50% decrease in mean annual Arctic CRF. Consequently, wintertime surface temperatures fall by up to 4 K on land and 2–8 K over the Arctic Ocean, thus significantly reducing the model’s pronounced warm bias. Freezedry also affects CCSM3’s sensitivity to greenhouse forcing. In a transient-CO2 experiment, the model version with freezedry warms up to 20% less in the North Polar and South Polar regions (1.5- and 0.5-K-smaller warming, respectively). Paradoxically, the muted high-latitude response occurs despite a much larger increase in cloud amount with freezedry during nonsummer months (when clouds warm the surface), apparently because of the colder modern reference climate. While improving the polar climate simulation in CCSM3, freezedry has virtually no influence outside of very cold regions and has already been implemented in another climate model, the Global Environmental and Ecological Simulation of Ecological Systems, version 1 (GENESIS1). Furthermore, the simplicity of this parameterization allows it to be readily incorporated into other GCMs, many of which also suffer from excessive wintertime polar cloudiness.
Lagrangian H/U3 Values Computed around Fronts Using a Fine-Resolution Numerical Model and Ferryboat-Monitored SST Dataset
Authors: Sun Youn-Jong , Isobe Atsuhiko
Published: May 2008

Front locations are identified as the local maximum of the sea surface temperature gradient revealed in the continuously ferryboat-monitored data in the Seto Inland Sea, Japan. In addition, Simpson and Hunter’s H/U3 values, where H is the water depth and U is the tidal-current amplitude, are computed at each cell using a fine-resolution, finite-volume ocean model to find the values at the fronts (i.e., Eulerian critical H/U3 values). Moreover, Lagrangian critical H/U3 values are computed using the same model in conjunction with particle-tracking experiments in which the particle’s H/U3 values saved along their trajectories are all averaged at each cell. In comparison with the Eulerian H/U3 values, it is revealed that the standard deviation of the Lagrangian critical values considerably reduces, especially for the fronts near straits. This accurate estimate of the critical H/U3 values shows that critical values depend on the tidal-current amplitude at the front locations. The dependency of critical H/U3 values on the tidal-current amplitude is likely due to dependency of the efficiency factor for vertical mixing in the original Simpson and Hunter formula on the amplitude. It is suggested that the efficiency factor for vertical mixing must be small (large) at locations with the large (small) tidal-current amplitude.
Vortex Interactions and Barotropic Aspects of Concentric Eyewall Formation
Authors: Kuo Hung-Chi , Schubert Wayne H. , Tsai Chia-Ling , Kuo Yu-Fen
Published: May 2008

Concentric eyewall formation can be idealized as the interaction of a tropical cyclone core with nearby weaker vorticity of various spatial scales. This paper considers barotropic aspects of concentric eyewall formation from modified Rankine vortices. In this framework, the following parameters are found to be important in concentric eyewall formation: vorticity strength ratio, separation distance, companion vortex size, and core vortex skirt parameter. A vorticity skirt on the core vortex affects the filamentation dynamics in two important ways. First, the vorticity skirt lengthens the filamentation time, and therefore slows moat formation in the region just outside the radius of maximum wind. Second, at large radii, a skirted core vortex induces higher strain rates than a corresponding Rankine vortex and is thus more capable of straining out the vorticity field far from the core. Calculations suggest that concentric structures result from binary interactions when the small vortex is at least 4–6 times as strong as the larger companion vortex. An additional requirement is that the separation distance between the edges of the two vortices be less than 6–7 times the smaller vortex radius. Broad moats form when the initial companion vortex is small, the vorticity skirt outside the radius of maximum wind is small, and the strength ratio is large. In concentric cases, an outer vorticity ring develops when the initial companion vortex is large, the vorticity skirt outside the radius of maximum wind is small, and the strength ratio is not too large. In general, when the companion vortex is 3 times as strong as the core vortex and the separation distance is 4–6 times the radius of the smaller vortex, a core vortex with a vorticity skirt produces concentric structures. In contrast, a Rankine vortex produces elastic interaction in this region of parameter space. Thus, a Rankine vortex of sufficient strength favors the formation of a concentric structure closer to the core vortex, while a skirted vortex of sufficient strength favors the formation of concentric structures farther from the core vortex. This may explain satellite microwave observations that suggest a wide range of radii for concentric eyewalls.
Bayesian Model Averaging’s Problematic Treatment of Extreme Weather and a Paradigm Shift That Fixes It
Authors: Bishop Craig H. , Shanley Kevin T.
Published: May 2008

Methods of ensemble postprocessing in which continuous probability density functions are constructed from ensemble forecasts by centering functions around each of the ensemble members have come to be called Bayesian model averaging (BMA) or “dressing” methods. Here idealized ensemble forecasting experiments are used to show that these methods are liable to produce systematically unreliable probability forecasts of climatologically extreme weather. It is argued that the failure of these methods is linked to an assumption that the distribution of truth given the forecast can be sampled by adding stochastic perturbations to state estimates, even when these state estimates have a realistic climate. It is shown that this assumption is incorrect, and it is argued that such dressing techniques better describe the likelihood distribution of historical ensemble-mean forecasts given the truth for certain values of the truth. This paradigm shift leads to an approach that incorporates prior climatological information into BMA ensemble postprocessing through Bayes’s theorem. This new approach is shown to cure BMA’s ill treatment of extreme weather by providing a posterior BMA distribution whose probabilistic forecasts are reliable for both extreme and nonextreme weather forecasts.
Competition and Truth in the Market for News
Authors: Gentzkow Matthew , Shapiro Jesse M
Published: May 2008

In this essay, we evaluate the case for competition in news markets from the perspective of economics. First, we consider the simple proposition that when more points of view are heard and defended, beliefs will converge to the truth. This concept of “competition” is several steps removed from market competition among actual media firms, but it has played a prominent role in the legal arguments for a free press. We then explore three mechanisms by which increasing competition, or more precisely increasing the number of independently-owned firms, can limit bias or distortions that originate on the supply-side of the media market: First, when governments attempt to manipulate news, competition can increase the likelihood that the media remain independent. Second, when news providers have an interest in manipulating consumers' beliefs, diversity in such incentives can reduce the risk of information being suppressed or distorted. Third, competition may drive firms to invest in providing timely and accurate coverage. Overall, we argue that there are robust reasons to expect competition to be effective in disciplining supply-side bias. Next, we ask how the effect of competition changes when distortions originate on the demand side of the market—when consumers themselves demand biased or less socially relevant news. We find that increased competition may or may not improve welfare in these cases, though we caution against using this as a justification for concentrating media power in the hands of state-controlled or regulated firms.