bluuebunny/crossref_metadata_2025 huggingface dataset:
Reliability analysis of static and dynamic fault-tolerant systems subject to probabilistic common-cause failures
Authors: Xing L , Boddu P , Sun Y , Wang W
Published: November 2009

Fault-tolerant systems designed with redundancy techniques are typically subject to common-cause failures, which are multiple dependent component failures caused by a shared root cause or a common cause (also known as a shock). There are two types of shocks: fatal and non-fatal. A fatal shock (FS) will fail all components of a system. A non-fatal shock (NFS) will affect only a subset of system components. Most of the existing shock models have assumed that the occurrence of an NFS results in deterministic and simultaneous failures of the affected components. In practice, however, the occurrence of an NFS may result in failures of different components with different probabilities of occurrence. This behaviour is referred to as probabilistic NFS. In this paper, we consider the effects of probabilistic NFS in the reliability analysis of fault-tolerant systems. Both an explicit method and an implicit method are proposed for incorporating probabilistic NFS in the reliability analysis of static systems. A Markov approach combined with the Poisson decomposition law is proposed for incorporating probabilistic NFS in the reliability analysis of dynamic systems. The proposed approaches are illustrated through the analyses of several examples.
Commentary—On the Interpretation of Temporal Inflation Parameters in Stochastic Models of Judgment and Choice
Authors: Hutchinson J. Wesley , Zauberman Gal , Meyer Robert
Published: November 2009

The implications of Salisbury and Feinberg's (2010) paper [Salisbury, L. C., F. M. Feinberg. 2010. Alleviating the constant stochastic variance assumption in decision research: Theory, measurement, and experimental test. Marketing Sci. 29(1) 1–17] for the process of model development and testing in the field of intertemporal choice analysis is explored. Although supporting the overall thrust of Salisbury and Feinberg's critique of previous empirical work in the area, we also see their paper as illustrating the dangers of drawing strong inferences about the behavioral interpretation of statistical model parameters without seeking convergent empirical evidence. In particular, we are skeptical about the extent to which the reported effects of temporal distance on the estimated scale parameter, σc, are uniquely, or even primarily, due to unobserved error inflation that reflects consumer's uncertainty about future utility. This interpretation is brought into question by several lines of reasoning. Conceptually, we note that “uncertainty” is different from “error” and that, for choice data, the error inflation model is mathematically identical to a model in which the scale parameter is a deterministic function of the temporal discount rate. Empirically, a reanalysis of data from previously published experiments does not consistently support temporal error inflation, temporal convergence of choice shares, or the scale parameter as an explanation of variety seeking in choice sequences. In our opinion, the cumulative results of research on intertemporal choice require models in which the attributes of choice alternatives are differentially discounted over time. Despite these findings, we advocate that choice researchers should indeed follow Salisbury and Feinberg's advice to not assume that error variances will be unaffected by experimental manipulations, and such effects should be explicitly modeled. We also agree that uncovering effects on error variance is just the first step, and the ultimate goal should be to rigorously explain the reasons for such effects.
Rejoinder—Temporal Stochastic Inflation in Choice-Based Research
Authors: Salisbury Linda Court , Feinberg Fred M.
Published: November 2009

We examine the specification and interpretation of discrete-choice models used in behavioral theory testing, with a focus on separating “coefficient scale” from “error scale,” particularly over time. Numerous issues raised in the thoughtful commentaries of Louviere and Swait [Louviere, J., J. Swait. 2010. Discussion of “Alleviating the constant stochastic variance assumption in decision research: Theory, measurement, and experimental test.” Marketing Sci. 29(1) 18–22] and Hutchinson, Zauberman, and Meyer (HZM) [Hutchinson, J. W., G. Zauberman, R. Meyer. 2010. On the interpretation of temporal inflation parameters in stochastic models of judgment and choice. Marketing Sci. 29(1) 23–31] are addressed, specifically the roles of response scaling, preference covariates, actual versus hypothetical consumption, “immediacy,” and heterogeneity, as well as key differences between the experimental setup in Salisbury and Feinberg [Salisbury, L. C., F. M. Feinberg. 2010. Alleviating the constant stochastic variance assumption in decision research: Theory, measurement, and experimental test. Marketing Sci. 29(1) 1–17] and those typifying intertemporal choice and construal level theory. We strongly concur with most of the general conclusions put forth by the commentary authors, but we also emphasize a central point made in our research that may have been lost: that the temporal inflation effects observed in our empirical analysis could be attributed to stochastic effects, deterministic influences, or an amalgam; appropriate inferences depend on the nature of one's data and stimuli. We also report on further analyses of our data, as well as a meta-analysis of HZM's Table 1 that is consistent with our original findings. Implications for, and dimensions relevant to, future research on temporal stochastic inflation and its role in choice-based research are discussed.
When More Alternatives Lead to Less Choice
Authors: Kuksov Dmitri , Villas-Boas J. Miguel
Published: November 2009

This paper shows that when the alternatives offered to consumers span the preference space (as it would be chosen by a firm), search or evaluation costs may lead consumers not to search and not to choose if too many or too few alternatives are offered. If too many alternatives are offered, then the consumer may have to engage in many searches or evaluations to find a satisfactory fit. This may be too costly and result in the consumer avoiding making a choice altogether. If too few alternatives are offered, then the consumer may not search or choose, fearing that an acceptable choice is unlikely. These two forces result in the existence of a finite optimal number of alternatives that maximizes the probability of choice.
Multidrug-Resistant Enterococcus faecium Endocarditis Treated with Combination Tigecycline and High-Dose Daptomycin
Authors: Schutt Amanda C , Bohm Nicole M
Published: November 2009

Objective:

To report a case of multidrug-resistant Enterococcus faecium requiring combination antibacterial therapy,

Case Summary:

A 39-year-old female presented with chest pain and a history of endocarditis 3 years prior to admission. Blood cultures were positive for E. faecium. She was treated initially with daptomycin 6 mg/kg daily, which was later increased to 8 mg/kg daily despite poor gentamicin clearance. A variety of antibiotics were used in combination with daptomycin, but the patient remained febrile, with positive blood cultures revealing vancomycin minimum inhibitory concentration (MIC) greater than 256 μg/mL and daptomycin MIC 3 μg/mL (and later, 4 μg/mL). Following the addition of tigecycline, the patient experienced rapid clinical and microbiologic improvement, and blood cultures remained negative 9 weeks after discharge.

Discussion:

Limited clinical data support the use of daptomycin for the treatment of E. faecium endocarditis, and information regarding the effects of escalating doses and combination therapy is scant. After failing multiple combination regimens, this patient responded to a combination of tigecycline and daptomycin. Daptomycin 8 mg/kg daily did not result in creatine kinase elevation in the face of evidence of possible renal dysfunction.

Conclusions:

Increasing doses of daptomycin may enhance efficacy without compromising safety, even in patients with some renal dysfunction. The combination of daptomycin and tigecycline may be useful for the treatment of multidrug-resistant E. faecium.
An Integrated Model for Understanding and Developing Resilience in the Face of Adverse Events
Authors: de Terte Ian , Becker Julia , Stephens Christine
Published: November 2009

The Five Part Model or Five Areas Model has been a pivotal component of cognitive behavioural therapy and the treatment of various psychological disorders. The Five Part Model consists of five components that represent the interaction of an individual's environment, thoughts, feelings, behaviours, and physical reactions. To date the Five Part Model has primarily been used to understand what has already happened to an individual; for example, when an individual is suffering from posttraumatic stress disorder or is being treated for other psychological difficulties. However, there has been limited application of the Five Part Model to the concept of resilience. Given the effectiveness of the model as an assessment and treatment tool, then it is possible that this model would also be effective in understanding how an individual deals with the aftermath of traumatic events such as disasters. Individual psychological variables are an essential part of whether an individual is resilient to adverse circumstances. However, this model should include as part of the individual's environment wider family, community and societal attributes. It is suggested that the Five Part Model be expanded to include such family, community and societal attributes to account for the influence these have on an individual's psychological resilience. A multidimensional model of resilience is proposed that will need to be scientifically tested; however, it is proposed that this model has application to the variety of disciplines that are involved in the domain of resilience. In addition, this model attempts to address any interdisciplinary barriers that exist, by ensuring that individual, family, community, and societal attributes are considered holistically as part of resilience building.
Home video films and the democratic imperative in contemporary Nigeria
Authors: Adeoti Gbemisola
Published: November 2009

The paper analyses the sociopolitical import of Nigerian home video films (Nollywood) against the backdrop of long years of military rule. Some titles discussed in the paper include: Saworo Ide/Brass Bells and Agogo Eewo/Gong of Taboo, Alaga Kansu/Local Council Chairman, Akobi
Gomina I & II/The Governor's Heir and Your Excellency.

The paper notes that while military dictatorship lasted, the film was more or less a medium for social diversion, cultural exhibition and religious affirmation. The inauguration of a civilian administration in
1999 has, however, led to the expansion of thematic possibilities through the screen. To this end, the Nigerian home video presents a framework for deepening people's participation in the process of democratization and development, as shown in the film analyses. In conclusion, the paper affirms
the potential of video film in tackling the challenges of social re-construction in a post-military democratization.
Autocrine and Paracrine Roles for ATP and Serotonin in Mouse Taste Buds
Authors: Huang Yijen A. , Dando Robin , Roper Stephen D.
Published: November 2009

Receptor (type II) taste bud cells secrete ATP during taste stimulation. In turn, ATP activates adjacent presynaptic (type III) cells to release serotonin (5-hydroxytryptamine, or 5-HT) and norepinephrine (NE). The roles of these neurotransmitters in taste buds have not been fully elucidated. Here we tested whether ATP or 5-HT exert feedback onto receptor (type II) cells during taste stimulation. Our previous studies showed NE does not appear to act on adjacent taste bud cells, or at least on receptor cells. Our data show that 5-HT released from presynaptic (type III) cells provides negative paracrine feedback onto receptor cells by activating 5-HT1Areceptors, inhibiting taste-evoked Ca2+mobilization in receptor cells, and reducing ATP secretion. The findings also demonstrate that ATP exerts positive autocrine feedback onto receptor (type II) cells by activating P2Y1 receptors and enhancing ATP secretion. These results begin to sort out how purinergic and aminergic transmitters function within the taste bud to modulate gustatory signaling in these peripheral sensory organs.
The Responses of Visual Neurons in the Frontal Eye Field Are Biased for Saccades
Authors: Lawrence Bonnie M. , Snyder Lawrence H.
Published: November 2009

Previous research suggests that visually responsive neurons in the frontal eye field (FEF) respond to visual targets even when they are not the goal of a saccadic eye movement. These results raise the possibility that these neurons respond to visual targets independent of the effector that is to be used to acquire the target locations. In the present study, we examined whether a plan to execute a saccade or a reach to a visual target influenced the response to and the representation of targets in the FEF. We recorded single unit responses to the onset of the target, during the delay period, and around the time of the movement, on interleaved saccade and reach trials of a delayed-response task. We found that the responses of approximately equal percentages of visual, visuomovement, and movement neurons (50%, 58%, and 58%, respectively) were greater on saccade trials than on reach trials in at least one interval of the delayed-response task. Converse biases, in favor of reaches, were much less frequent (13%, 10%, and 19%, in visual, visuomovement, and movement neurons respectively). Thus, although visual neurons may not be directly involved in triggering saccadic eye movements, they are nonetheless highly saccade-biased, with percentages comparable to neurons that are directly involved in triggering saccadic eye movements.
From Neurons to Circuits: Linear Estimation of Local Field Potentials
Authors: Rasch Malte , Logothetis Nikos K. , Kreiman Gabriel
Published: November 2009

Extracellular physiological recordings are typically separated into two frequency bands: local field potentials (LFPs) (a circuit property) and spiking multiunit activity (MUA). Recently, there has been increased interest in LFPs because of their correlation with functional magnetic resonance imaging blood oxygenation level-dependent measurements and the possibility of studying local processing and neuronal synchrony. To further understand the biophysical origin of LFPs, we asked whether it is possible to estimate their time course based on the spiking activity from the same electrode or nearby electrodes. We used “signal estimation theory” to show that a linear filter operation on the activity of one or a few neurons can explain a significant fraction of the LFP time course in the macaque monkey primary visual cortex. The linear filter used to estimate the LFPs had a stereotypical shape characterized by a sharp downstroke at negative time lags and a slower positive upstroke for positive time lags. The filter was similar across different neocortical regions and behavioral conditions, including spontaneous activity and visual stimulation. The estimations had a spatial resolution of ∼1 mm and a temporal resolution of ∼200 ms. By considering a causal filter, we observed a temporal asymmetry such that the positive time lags in the filter contributed more to the LFP estimation than the negative time lags. Additionally, we showed that spikes occurring within ∼10 ms of spikes from nearby neurons yielded better estimation accuracies than nonsynchronous spikes. In summary, our results suggest that at least some circuit-level local properties of the field potentials can be predicted from the activity of one or a few neurons.
Inositol 1,4,5-Trisphosphate 3-Kinase A Functions As a Scaffold for Synaptic Rac Signaling
Authors: Kim Il Hwan , Park Soon Kwon , Hong Soon Taek , Jo Yong Sang , Kim Eun Joo , Park Eun Hye , Han Seung Baek , Shin Hee-Sup , Sun Woong , Kim Hyun Taek , Soderling Scott H. , Kim Hyun
Published: November 2009

Activity-dependent alterations of synaptic contacts are crucial for synaptic plasticity. The formation of new dendritic spines and synapses is known to require actin cytoskeletal reorganization specifically during neural activation phases. Yet the site-specific and time-dependent mechanisms modulating actin dynamics in mature neurons are not well understood. In this study, we show that actin dynamics in spines is regulated by a Rac anchoring and targeting function of inositol 1,4,5-trisphosphate 3-kinase A (IP3K-A), independent of its kinase activity. On neural activation, IP3K-A bound directly to activated Rac1 and recruited it to the actin cytoskeleton in the postsynaptic area. This focal targeting of activated Rac1 induced spine formation through actin dynamics downstream of Rac signaling. Consistent with the scaffolding role of IP3K-A, IP3K-A knock-out mice exhibited defects in accumulation of PAK1 by long-term potentiation-inducing stimulation. This deficiency resulted in a reduction in the reorganization of actin cytoskeletal structures in the synaptic area of dentate gyrus. Moreover, IP3K-A knock-out mice showed deficits of synaptic plasticity in perforant path and in hippocampal-dependent memory performances. These data support a novel model in which IP3K-A is critical for the spatial and temporal regulation of spine actin remodeling, synaptic plasticity, and learning and memory via an activity-dependent Rac scaffolding mechanism.
Reference Frame of the Ventriloquism Aftereffect
Authors: Kopčo Norbert , Lin I-Fan , Shinn-Cunningham Barbara G. , Groh Jennifer M.
Published: November 2009

Seeing the image of a newscaster on a television set causes us to think that the sound coming from the loudspeaker is actually coming from the screen. How images capture sounds is mysterious because the brain uses different methods for determining the locations of visual versus auditory stimuli. The retina senses the locations of visual objects with respect to the eyes, whereas differences in sound characteristics across the ears indicate the locations of sound sources referenced to the head. Here, we tested which reference frame (RF) is used when vision recalibrates perceived sound locations. Visually guided biases in sound localization were induced in seven humans and two monkeys who made eye movements to auditory or audiovisual stimuli. On audiovisual (training) trials, the visual component of the targets was displaced laterally by 5–6°. Interleaved auditory-only (probe) trials served to evaluate the effect of experience with mismatched visual stimuli on auditory localization. We found that the displaced visual stimuli induced ventriloquism aftereffect in both humans (∼50% of the displacement size) and monkeys (∼25%), but only for locations around the trained spatial region, showing that audiovisual recalibration can be spatially specific. We tested the reference frame in which the recalibration occurs. On probe trials, we varied eye position relative to the head to dissociate head- from eye-centered RFs. Results indicate that both humans and monkeys use a mixture of the two RFs, suggesting that the neural mechanisms involved in ventriloquism occur in brain region(s) using a hybrid RF for encoding spatial information.
Selective Targeting of the Dendrites of Corticothalamic Cells by Thalamic Afferents in Area 17 of the Cat
Authors: da Costa Nuno Maçarico , Martin Kevan A. C.
Published: November 2009

Pyramidal cells of layer 6 in cat visual cortex are the source of the corticothalamic projection, and their recurrent collaterals provide substantially more excitatory synapses in layer 4 than does the thalamic input. They have predominantly simple receptive fields and can be driven monosynaptically by electrically stimulating thalamic relay cells. Layer 6 cells could thus provide a significant disynaptic amplification of the thalamic input to layer 4, particularly since their synapses facilitate, unlike the thalamic afferents whose synapses depress. However, purely geometric considerations of the relation of their dendritic trees to the thalamic input indicate that they should form a far smaller number of synapses with thalamic afferents than do the simple cells of layer 4. We thus analyzed quantitatively the thalamic input to identified corticothalamic cells by labeling the thalamic afferents and corticothalamic cellsin vivo. We made a correlated light and electron microscopic study of 73 “contacts” between thalamic afferents and five corticothalamic cells. The electron microscope revealed that only 24 of the contacts identified at light microscope level were indeed synapses and, contrary to geometric predictions, virtually all were located on spines on the basal dendrites. Our quantitative estimates indicate that the corticothalamic cells form even fewer synapses with the thalamic afferents than predicted by geometric considerations and only 1/10 as many as do the layer 4 simple cells. These data strongly suggest it is the collective computation of cortical neurons, not the monosynaptic thalamic input, that determines the output of the corticothalamic cells.
Decreased Firing of Striatal Neurons Related to Licking during Acquisition and Overtraining of a Licking Task
Authors: Tang Chris C. , Root David H. , Duke Dawn C. , Zhu Yun , Teixeria Kate , Ma Sisi , Barker David J. , West Mark O.
Published: November 2009

Neurons that fire in relation to licking, in the ventral part of the dorsolateral striatum (DLS), were studied during acquisition and performance of a licking task in rats for 14 sessions (2 h/d). Task learning was indicated by fewer errors of omission of licking and improved movement efficiency (i.e., shorter lick duration) over sessions. Number of licks did not change over sessions. Overtraining did not result in habit formation, as indicated by similar reductions of licking responses following devaluation by satiety in both early and late sessions. Twenty-nine lick neurons recorded and tracked over sessions exhibited a significant linear decrease in average firing rate across all neurons over sessions, correlating with concurrent declines in lick duration. Individually, most neurons (86%) exhibited decreased firing rates, while a small proportion (14%) exhibited increased firing rates, during lick movements that were matched over sessions. Reward manipulations did not alter firing patterns over sessions. Aside from the absence of habit formation, striatal processing during unconditioned movements (i.e., licking) was characterized by high activity of movement-related neurons during early performance and decreased activity of the same neurons during overtraining, similar to our previous report of head movement neurons during acquired, skilled, instrumental head movements that ultimately became habitual (Tang et al., 2007). Decreased activity in DLS neurons may reflect a common neural mechanism underlying improvement in movement efficiency with overtraining. Nonetheless, the decreased striatal firing in relation to a movement that did not become habitual demonstrates that not all DLS changes reflect habit formation.
Dynamic Range Adaptation to Sound Level Statistics in the Auditory Nerve
Authors: Wen Bo , Wang Grace I. , Dean Isabel , Delgutte Bertrand
Published: November 2009

The auditory system operates over a vast range of sound pressure levels (100–120 dB) with nearly constant discrimination ability across most of the range, well exceeding the dynamic range of most auditory neurons (20–40 dB). Dean et al. (2005) have reported that the dynamic range of midbrain auditory neurons adapts to the distribution of sound levels in a continuous, dynamic stimulus by shifting toward the most frequently occurring level. Here, we show that dynamic range adaptation, distinct from classic firing rate adaptation, also occurs in primary auditory neurons in anesthetized cats for tone and noise stimuli. Specifically, the range of sound levels over which firing rates of auditory nerve (AN) fibers grows rapidly with level shifts nearly linearly with the most probable levels in a dynamic sound stimulus. This dynamic range adaptation was observed for fibers with all characteristic frequencies and spontaneous discharge rates. As in the midbrain, dynamic range adaptation improved the precision of level coding by the AN fiber population for the prevailing sound levels in the stimulus. However, dynamic range adaptation in the AN was weaker than in the midbrain and not sufficient (0.25 dB/dB, on average, for broadband noise) to prevent a significant degradation of the precision of level coding by the AN population above 60 dB SPL. These findings suggest that adaptive processing of sound levels first occurs in the auditory periphery and is enhanced along the auditory pathway.
Sex‐specific, seasonal foraging tactics of adult grey seals (Halichoerus grypus) revealed by state–space analysis
Authors: Breed Greg A. , Jonsen Ian D. , Myers Ransom A. , Bowen W. Don , Leonard Marty L.
Published: November 2009

In many large pelagic animals, observing behavior is limited to observation by radio or satellite telemetry. In many cases, discriminating different behaviors from telemetry data has been a key, but often elusive, goal. Here we use state–space models (SSMs) to fit a correlated random walk (CRW) model that switches between two unobserved behavioral states (nominally foraging and traveling) to 41 male and 43 female adult grey seal (Halichoerus grypus) satellite telemetry tracks. The SSM results reveal markedly different spatial behavior between the sexes, fitting well with sexual size dimorphism and known dietary differences, suggesting that the sexes deal with seasonal prey availability and reproductive costs differently. From these results we were also able to produce behaviorally informed habitat use maps, showing a complex and dynamic network of small, intensely used foraging areas. Our flexible SSM approach clearly demonstrates sex‐related behavioral differences, fine scale spatial and temporal foraging patterns, and a clearer picture of grey seal ecology and role in the Scotian Shelf ecosystem.
Patterns and rules for sensitivity and elasticity in population projection matrices
Authors: Carslake David , Townley Stuart , Hodgson David J.
Published: November 2009

Sensitivity and elasticity analysis of population projection matrices (PPMs) are established tools in the analysis of structured populations, allowing comparison of the contributions made by different demographic rates to population growth. In some commonly used structures of PPM, however, there are mathematically inevitable patterns in the relative sensitivity and elasticity of certain demographic rates. We take a simulation approach to investigate these mathematical constraints for a range of PPM models. Our results challenge some previously proposed constraints on sensitivity and elasticity. We also identify constraints beyond those that have already been proven mathematically and promote them as candidates for future mathematical proof. A general theme among these rules is that changes to the demographic rates of older or larger individuals have less impact on population growth than do equivalent changes among younger or smaller individuals. However, the validity of these rules in each case depends on the choice between sensitivity and elasticity, the growth rate of the population, and the PPM structure used. If the structured population conforms perfectly to the assumptions of the PPM used to model it, the rules we describe represent biological reality, allowing us to prioritize management strategies in the absence of detailed demographic data. Conversely, if the model is a poor fit to the population (specifically, if demographic rates within stages are heterogeneous), such analyses could lead to inappropriate management prescriptions. Our results emphasize the importance of choosing a structured population model that fits the demographics of the population.
Inferring host–parasite relationships using stable isotopes: implications for disease transmission and host specificity
Authors: Stapp Paul , Salkeld Daniel J.
Published: November 2009

Identifying the roles of different hosts and vectors is a major challenge in the study of the ecology of diseases caused by multi‐host pathogens. Intensive field studies suggested that grasshopper mice (Onychomys leucogaster) help spread the bacterium that causes plague (Yersinia pestis) in prairie dog colonies by sharing fleas with prairie dogs (Cynomys ludovicianus); yet conclusive evidence that prairie dog fleas (Oropsylla hirsuta) feed on grasshopper mice is lacking. Using stable nitrogen isotope analysis, we determined that many blood‐engorged O. hirsuta collected from wild grasshopper mice apparently contained blood meals of prairie dogs. These results suggest that grasshopper mice may be infected with Y. pestis via mechanisms other than flea feeding, e.g., early phase or mechanical transmission or scavenging carcasses, and raise questions about the ability of grasshopper mice to maintain Y. pestis in prairie dog colonies during years between plague outbreaks. They also indicate that caution may be warranted when inferring feeding relationships based purely on the occurrence of fleas or other haematophagous ectoparasites on hosts. Stable‐isotope analysis may complement or provide a useful alternative to immunological or molecular techniques for identifying hosts of cryptically feeding ectoparasites, and for clarifying feeding relationships in studies of host–parasite interactions.
Nutrient availability and phytoplankton nutrient limitation across a gradient of atmospheric nitrogen deposition
Authors: Elser James J. , Kyle Marcia , Steger Laura , Nydick Koren R. , Baron Jill S.
Published: November 2009

Atmospheric nitrogen (N) deposition to lakes and watersheds has been increasing steadily due to various anthropogenic activities. Because such anthropogenic N is widely distributed, even lakes relatively removed from direct human disturbance are potentially impacted. However, the effects of increased atmospheric N deposition on lakes are not well documented. We examined phytoplankton biomass, the absolute and relative abundance of limiting nutrients (N and phosphorus [P]), and phytoplankton nutrient limitation in alpine lakes of the Rocky Mountains of Colorado (USA) receiving elevated (>6 kg N·ha−1·yr−1) or low (<2 kg N·ha−1·yr−1) levels of atmospheric N deposition. High‐deposition lakes had higher NO3‐N and total N concentrations and higher total N : total P ratios. Concentrations of chlorophyll and seston carbon (C) were 2–2.5 times higher in high‐deposition relative to low‐deposition lakes, while high‐deposition lakes also had higher seston C:N and C:P (but not N:P) ratios. Short‐term enrichment bioassays indicated a qualitative shift in the nature of phytoplankton nutrient limitation due to N deposition, as high‐deposition lakes had an increased frequency of primary P limitation and a decreased frequency and magnitude of response to N and to combined N and P enrichment. Thus elevated atmospheric N deposition appears to have shifted nutrient supply from a relatively balanced but predominantly N‐deficient regime to a more consistently P‐limited regime in Colorado alpine lakes. This adds to accumulating evidence that sustained N deposition may have important effects on lake phytoplankton communities and plankton‐based food webs by shifting the quantitative and qualitative nature of nutrient limitation.
Testing species abundance models: a new bootstrap approach applied to Indo‐Pacific coral reefs
Authors: Connolly Sean R. , Dornelas Maria , Bellwood David R. , Hughes Terence P.
Published: November 2009

Patterns in the commonness and rarity of species are a fundamental characteristic of ecological assemblages; however, testing between alternative models for such patterns remains an important challenge. Conventional approaches to fitting or testing species abundance models often assume that species, not individuals, are the units that are sampled and that species' abundances are independent of one another. Here we test three different models (the Poisson lognormal, the negative binomial, and the neutral, “zero‐sum multinomial” [ZSM]) against species abundance distributions of Indo‐Pacific corals and reef fishes. We derive and apply several alternative bootstrap analyses of model fit, each of which makes different assumptions about how species abundance data are sampled, and we assess the extent to which tests of model fit are sensitive to such assumptions. For all models, goodness of fit is remarkably consistent, regardless of whether one assumes that species or individuals are the units that are sampled or whether or not one assumes that species' abundances are statistically independent of one another. However, goodness‐of‐fit estimates are approximately twice as precise and detect lack of model fit more frequently, when based on sampling of individuals, rather than species. Bootstrap analyses indicate that the Poisson lognormal distribution exhibits substantially better fit to species abundance patterns, consistent with model selection analyses. In particular, heterogeneity in species abundances (many rare and few highly abundant species) is too great to be captured by the ZSM model or the negative binomial model and is best explained by models that predict species abundance patterns that are much closer, but not identical, to the lognormal distribution. More broadly, our bootstrap analyses suggest that estimates of model fit are likely to be robust to assumptions about the statistical interdependence of species abundances, but that tests of model fit are more powerful when they assume sampling of individuals, rather than species. Such individual‐based tests therefore may be able to identify lack of model fit where previous tests have been inconclusive.
Chemical niche differentiation among sympatric species of orchid bees
Authors: Zimmermann Yvonne , Ramírez Santiago R. , Eltz Thomas
Published: November 2009

Male Neotropical orchid bees (Euglossini) collect volatile substances (fragrances) from flowers and other sources (e.g., decaying wood) and store them in specialized hind tibial pockets. The accumulated chemicals are later emitted during courtship display, presumably to lure conspecific females for mating. We analyzed tibial fragrances of males of 15 sympatric Panamanian species in the genus Euglossa to test whether communities of euglossine bees are chemically structured, and to elucidate whether male fragrance signals evolve to convey premating isolation. Our analysis revealed substantial chemical disparity among all lineages. Disparity was mediated by compounds that were exclusive to certain species but also by differences in relative quantity of shared compounds. We mapped tibial fragrance compounds present in each species on a DNA‐based phylogeny (reconstructed using partial sequences of COI, EF1‐α, ArgK, and Pol‐II) and found that most dominant compounds were highly homoplasious. In an analysis of chemical differentiation in relation to phylogenetic divergence through time, disparity was greater than expected from a null model at any point during evolutionary history, suggesting that diversifying selection has shaped fragrance phenotypes. Notably, chemical disparity was greater within recently diverged lineages than among them, suggesting that chemical preferences in orchid bees evolved rapidly in the early stages of species divergence. We postulate communication interference as the possible mechanism behind the observed fragrance differentiation, which may be the product of reproductive character (fragrance) displacement. Our findings are consistent with the hypothesis that male fragrance signals evolve to convey premating isolation.
Relative effects of maternal and juvenile food availability for a marine snail
Authors: Sman Johnvander , Phillips Nicole E. , Pfister Catherine A.
Published: November 2009

The relative importance of maternal vs. juvenile food environment on juvenile performance is poorly understood, particularly for marine organisms. Here, we use a manipulative experiment to compare the influence of maternal and juvenile nutrition on early juvenile performance for a marine gastropod (Cominella virgata) with completely benthic development. Adult whelks adjusted growth and capsule volume to food availability, but there was no effect on the initial size or number of their hatchlings, which varied greatly within and among females. Although hatchling survivorship was also unaffected by maternal nutrition, juveniles fed lower food showed decreased survivorship. By contrast, growth of C. virgata hatchlings in the month after hatching was higher for hatchlings from high‐food mothers, suggesting important carry‐over effects of maternal nutrition on early juveniles, mediated by a trait other than offspring size. This maternal effect faded in the second month after hatching, as the hatchling environment became more important.
Inducible defenses in prey intensify predator cannibalism
Authors: Kishida Osamu , Trussell Geoffrey C. , Nishimura Kinya , Ohgushi Takayuki
Published: November 2009

Trophic cascades are often a potent force in ecological communities, but abiotic and biotic heterogeneity can diffuse their influence. For example, inducible defenses in many species create variation in prey edibility, and size‐structured interactions, such as cannibalism, can shift predator diets away from heterospecific prey. Although both factors diffuse cascade strength by adding heterogeneity to trophic interactions, the consequences of their interaction remain poorly understood. We show that inducible defenses in tadpole prey greatly intensify cannibalism in predatory larval salamanders. The likelihood of cannibalism was also strongly influenced by asymmetries in salamander size that appear to be most important in the presence of defended prey. Hence, variation in prey edibility and the size structure of the predator may synergistically affect predator–prey population dynamics by reducing prey mortality and increasing predator mortality via cannibalism. We also suggest that the indirect effects of prey defenses may shape the evolution of predator traits that determine diet breadth and how trophic dynamics unfold in natural systems.
Seasonal sex allocation by Common Grackles? Revisiting a foundational study
Authors: Maddox J. Dylan , Weatherhead Patrick J.
Published: November 2009

Despite the general importance of replication in science, relatively few behavioral ecology studies are repeated. Here we repeat the seminal 1977 research of H. F. Howe, who found that the proportion of male nestlings at hatching in nests of Common Grackles (Quiscalus quiscula) increased as the breeding season progressed. Howe interpreted this pattern as an adaptive response to changing food conditions that favored greater production of daughters (the sex less expensive to rear) when food was scarce and sons when food was more abundant. Using DNA‐based sexing and larger samples, we found no evidence of nonrandom seasonal sex allocation and no evidence that sons were more vulnerable to starvation than daughters. These patterns also prevailed among renesting efforts late in the season, when starvation was extreme. Although there is no way to exclude the possibility that grackles employed different sex allocation tactics in the two studies, similarities in weather, habitat, nesting phenology, and starvation rates make it seem unlikely that ecological differences between our study and Howe's explain the disparate results, whereas failure of assumptions that Howe was unable to test seems more plausible.
Seed size, more than nutrient or tannin content, affects seed caching behavior of a common genus of Old World rodents
Authors: Wang Bo , Chen Jin
Published: November 2009

Scatter‐hoarding rodents play an important dispersal role for many large‐seeded plants. Seed traits affect their foraging behavior; however, it is difficult to isolate their effects because of the covariance among traits. Here, we used artificial seeds to partition the effects of seed size, tannin content, and nutrient content on scatter‐hoarding rodents in a natural pine forest in Northwest Yunnan, China. Apodemus, a common genus of Old World rodents, consistently consumed small seeds in situ but removed medium‐sized seeds (1.2–2.5 cm in diameter) and transported bigger seeds farther. Seed nutrient and tannin contents also significantly influenced rodents' behavior, but response varied substantially between years. Rodent behavior did involve some aspects of multivariate optimization. Our results strongly indicate that seed size is a decisive factor for scatter‐hoarding rodents in the choice between seed predation and dispersal, while nutrient and tannin content played a less consistent role, possibly responding to confounding factors in the community. This result also has important implications for seed production by trees, which can improve the probability of long‐distance dispersal of high‐quality offspring by simply making them larger. The ability to tease apart the relative influence of different seed traits on the behavior of predators provides powerful insight into this important coevolutionary dynamic.
A Theory of the Relational Work of Nurses
Authors: DeFrino Daniela Terrizzi
Published: November 2009

The subject of nurses’ relational work articulates a reality that exists but is not seen. However, it is the awareness of this reality that leads to the discovery of where nurses hold their professional power. A theory of the relational work of nurses is the derived theory presented in this article from the parent theory of the relational work of women (Fletcher, Jordan, & Miller, 2000). The new theory exposes the relational work of nurses as the source of their power and value. It explains the relational dynamics of nurses’ work, its inherent value, and the need for it to be explicitly recognized as the process by which nurses achieve positive patient and professional outcomes. The new theory proposes that because relational work is institutionally “disappeared,” nurses therefore demonstrate lack of caring, patient detachment, and burnout. This theory, if tested, would be an attempt to articulate and make valuable the skills and strengths that nurses enact to get their job done.
SAPHO Syndrome Diagnosis and Treatment: Report of Five Cases and Review of the Literature
Authors: Matzaroglou Ch , Velissaris D , Karageorgos A , Marangos M , Panagiotopoulos E , Karanikolas M
Published: November 2009

Background:

The term “SAPHO (Synovitis, Acne, Pustulosis, Hyperostosis and Osteitis) syndrome” includes a variety of musculoskeletal disorders associated with skin conditions; Osteitis is the most prominent skeletal lesion, whereas palmoplantar pustulosis and acne are the main skin lesions. Diagnosing SAPHO syndrome is difficult, because this syndrome is often confused with suppurative osteomyelitis, which has similar clinical and pathologic findings. SAPHO diagnosis is even more difficult when atypical sites are involved and there are no skin lesions.

Patients and Methods:

This case series presents five patients (3 women, 2 men), ages 27 to 44 years, who came to the Orthopaedic Department outpatient clinic for evaluation of pain in the humerus, clavicle, sacroiliac joints, and/or distal radius, and were diagnosed with SAPHO syndrome. Clinical and radiologic findings, treatment and outcome data, with up to 4 years of follow-up are presented. An extensive discussion of the clinical presentation, published literature, treatment options and outcome of SAPHO syndrome is also included.

Results:

Once the diagnosis of SAPHO syndrome was established, treatment with antibiotics (clindamycin) and non steroid anti-inflammatory drugs (lornoxicam) was remarkably effective. All patients did well and remained symptom free for up to four years, after a 3-8 month course of treatment.

Interpretation:

SAPHO syndrome should be included in the differential diagnosis when evaluating patients with lytic, sclerotic, or hyperostotic bone lesions and pain. Prompt SAPHO syndrome recognition, followed by appropriate therapy with antibiotics and NSAIDs can produce rapid symptom resolution, while avoiding unnecessary procedures and longterm antibiotic therapy.
Competitive Processes and the Evolution of Governance Structures
Authors: Ricketts Martin
Published: November 2009

Cet article examine la concurrence entre des structures de gouvernance des entreprises. Il y est souligné quune panoplie de structures constitutionnelles peut être observée dans le cadre marchand et que cette variété a servi des objectifs transactionnels importants sur un plan historique. Larticle met en contraste les approches coasienne et autrichienne de lexplication des structures de gouvernance. Nous examinons la tendance récente du déplacement de la propriété des entreprises vers les investisseurs par opposition aux arrangements coopératifs et mutuels. L  a r gument a t ion sout i ent que lintervention étatique peut être une explication importante des tendances récentes au Royaume Uni, notamment dans le domaine des institutions financières. Les suggestions selon lesquelles des modèles de gouvernance des entreprises par les partenaires devraient être introduits à travers lintervention de lEtat ignorent à la fois les coûts de transaction et limportance dassurer laffectation du talent entrepreneurial en direction des ressources économiques.This paper considers competition between governance arrangements for firms. It is argued that a variety of constitutional structures can be observed in the market and that historically this variety has served important transactional purposes. The Coasian and Austrian approaches to the explanation of governance arrangements are contrasted. Recent trends towards investor ownership of firms and away from co-operative and mutual arrangements are considered. It is argued that government regulatory intervention may be an important explanation for recent trends in the UK, especially in the area of financial institutions. Suggestions that stakeholder models of firm governance should be introduced through state intervention ignore considerations both of transactions costs and the importance of ensuring the allocation of entrepreneurial talent to the direction of economic resources.
The Political Economy of the Just Price: What the School of Salamanca Has To Say in the Age of Corruption
Authors: Vergés Josep C.
Published: November 2009

La tradition éthique en économie politique a été régénérée par lEcole de Salamanque, mais nous ne sommes pas habitués à associer le libéralisme aux scholastiques qui avaient élaboré une théorie du juste prix de validité universelle. Le marché a perdu sa dimension morale avec le rationalisme et, non dans une moindre mesure, à travers le biais religieux de la théorie de la valeur travail. Quand elle fut redécouverte en tant quorigine véritable de la valeur, lutilité ne recouvrit pas sa portée morale, en raison du traitement mathématique quon lui réserva. Le rationalisme a supprimé toute conception dévolution sociale en même temps quil a favorisé lintervention. Cependant, dans cette ère de corruption, un retour à lacception de sens commun des prix requiert, selon lauteur, le franchissement dune étape supplémentaire, celui de maintenir lancrage éthique du juste prix ou du prix du marché.The ethical tradition in political economy was regenerated by the School of Salamanca, but we are not used to associating liberalism with these Scholastics who built a theory of the just price with universal validity. The market lost its moral dimension with rationalism, not least through the religious bias of the labor theory of value. When rediscovered as the correct source of value, utility did not regain its former moral significance because of mathematical treatment. Rationalism has suppressed any concept of social evolution while promoting intervention, but, in the age of corruption, a return to the common sense of prices, the author argues, requires the further step of upholding the ethical standards of the just price or market price.