			Home About us Contact

Warning Signal (warning + signal)

Distribution by Scientific Domains

Life Sciences	58%
Medical Sciences	12%
Business, Economics, Finance and Accounting	12%

Kinds of Warning Signal

early warning signal

Selected Abstracts

WARNING SIGNALS OR DANGEROUS OPPORTUNITIES?

EDUCATIONAL THEORY, Issue 4 2000
AND EDUCATIONAL POLICY SHIFTS, GENDER, GLOBALIZATION
First page of article [source]

Potential Use of Biomarkers in Zooplankton as Early Warning Signals of Ecotoxicological Risk in the Marine Food Chain

MARINE ECOLOGY, Issue 2002
Roberta Minutoli
Abstract. Zooplankton is an essential component of the marine and brackish food chains. The ecotoxicological risk of zooplanktonic communities, estimated by the modern methodological approach of biomarkers, can be used as an early warning signal of ecosystem health. The aim of this project is to estimate the potential use of several biomarkers (esterases, mixed function oxidases, porphyrins) in zooplanktonic organisms. Studies were carried out with different zooplanktonic crustaceans: the copepods Acartia margalefi and Acartia latisetosa collected in Ganzirri Lake (Messina); the mysid Siriella clausi collected in Faro Lake (Messina); the mysids Diamysis bahirensis, Siriella armata and Mysidopsis gibbosa collected in Stagnone di Marsala (Palermo); the Antarctic euphausiids Euphausia crystallorophias and Euphausia superba; the am-phipod Streetsia challengeri and the euphausiid Meganycthiphanes norvegica collected after a shore-stranding along Messina's Ionian coast. Moreover, experiments were carried out with the benthic decapods Eriphia verrucosa and Pachygrapsus marmoratus from a rocky shore of Messina's Ionian coast. Acetylcholinesterase activity (AChE) was determined in homogenates of whole organisms. The key result of this project concerns the different AChE activity basal values of different crustacean species. Particular attention should be paid to the difference in basal activity found between the Antarctic and the Mediterranean species. [source]

Do ,Quiet' Places Make Animals Placid?

ETHOLOGY, Issue 6 2005
Island vs.
Most animals that possess potent venom display a wide variety of warning messages to discourage predators. Tiger snakes are large and highly venomous elapids that exhibit these anti-predator behaviours. We compared the anti-predator behaviours of two neighbouring and genetically indistinguishable populations in Western Australia (Herdsman Lake, HL and Carnac Island, CI). CI is free from human, native and feral predation. All of these factors represent a continual threat on HL situated on the mainland. Neither body size, nor sex influenced defensive behaviours. However, we observed a marked inter-population difference among adults in the degree to which anti-predator behaviours were displayed when snakes were continually aggravated: HL snakes exhibited a typical warning signal (flat-neck) and bite, while CI snakes remained very docile. In stark contrast, neonates of both populations exhibited marked anti-predator behaviours and both populations were indistinguishable in terms of the intensity of display. Neonates reared in captivity, hence regularly confronted by human predators, became more defensive in comparison with neonates exposed to natural conditions on CI; similarly several adult CI snakes kept in captivity became more defensive. Our results highlight the extreme behavioural plasticity of snakes. We also hypothesize that CI snakes may become more placid over time as they grow up in an environment free from predation. [source]

Louisiana waterthrushes (Seiurus motacilla) and habitat assessments as cost-effective indicators of instream biotic integrity

FRESHWATER BIOLOGY, Issue 10 2006
B. J. MATTSSON
Summary 1. Benthic stream animals, in particular macroinvertebrates, are good indicators of water quality, but sampling can be laborious to obtain accurate indices of biotic integrity. Thus, tools for bioassessment that include measurements other than macroinvertebrates would be valuable additions to volunteer monitoring protocols. 2. We evaluated the usefulness of a stream-dependent songbird, the Louisiana waterthrush (waterthrush, Seiurus motacilla) and the Environmental Protection Agency Visual Habitat Assessment (EPA VHA) as indicators of the macrobenthos community in headwater streams of the Georgia Piedmont, U.S.A. We sampled macrobenthos, surveyed waterthrushes and measured habitat characteristics along 39 headwater reaches across 17 catchments ranging from forested to heavily urbanised or grazed by cattle. 3. Of the indicators considered, waterthrush occupancy was best for predicting relative abundances of macrobenthic taxa, while the EPA VHA was best for predicting Ephemeroptera,Plecoptera,Trichoptera (EPT) richness. Individual components of EPA VHA scores were much less useful as indicators of EPT richness and % EPT when compared with the total score. Waterthrushes were found along streams with higher % EPT, a lower Family Biotic Index (FBI) values and greater macrobenthos biomass. 4. While macroinvertebrates remain one of the most direct indicators of stream water quality, stream bird surveys and reach-scale habitat assessments can serve as cost-effective indicators of benthic macroinvertebrate communities. Using stream-dependent birds as an early warning signal for degradation of stream biotic integrity could improve the efficacy of catchment monitoring programmes in detecting and identifying perturbations within the catchment. [source]

Characterizing the pigment composition of a variable warning signal of Parasemia plantaginis larvae

FUNCTIONAL ECOLOGY, Issue 4 2010
Carita Lindstedt
Summary 1.,Aposematic animals advertise their defences to predators via warning signals that often are bright colours combined with black patterns. Predation is assumed to select for large pattern elements and conspicuousness of warning signals because this enhances avoidance learning of predators. However, conspicuousness of the colour pattern can vary among individuals of aposematic species, suggesting that warning signal expression may be constrained by opposing selection pressures. If effective warning signals are costly to produce, variation in signal expression may be maintained via physiological trade-offs. To understand the costs of signalling that might underlay both physiological and ecological trade-offs, it is crucial to identify the pigments involved in aposematic traits, how they or their precursors are acquired and how their production and/or deposition interact with other physiological processes. 2.,We characterized the pigments responsible for the genetically and phenotypically variable orange-black warning signal of the hairy larvae of an Arctiid moth, Parasemia plantaginis. We tested orange and black coloured hairs for the presence of six candidate pigment types using high-performance liquid chromatography, spectral and solubility analyses. 3.,After excluding the presence of carotenoids, ommochromes, pterins and pheomelanins in orange hairs, our results suggest that tiger moth larvae produce their orange warning signal by depositing both diet-derived flavonoids and trace levels of synthesized eumelanin in their hairs. The nearby black hairs are coloured by eumelanin. 4.,In light of previous studies, we conclude that although a large orange patch increases the 1larvae's antipredator efficacy, variation in the size of orange patches within a population can be driven by scarcity of flavonoids in diet. However, traces of eumelanin found in the orange hairs of the larvae may also play a significant role in the maintenance of the signal pattern on poor quality diets. 5.,The goal of the future studies will be to test the condition dependence of pigment deposition in aposematic colour patterns by directly manipulating relevant nutritional parameters such as dietary flavonoid or nitrogen content (i.e. amino acid content). [source]

Contingent negative variation elicited before jaw and tongue movements

JOURNAL OF ORAL REHABILITATION, Issue 12 2005
K. YOSHIDA
summary, Contingent negative variation (CNV) is a negative brain potential occurring between two successive stimuli when the first stimulus is a warning and the second stimulus requires a motor response. The CNV is interpreted as an expression of the cognitive processes in preparation for a response directed to a purpose. Using 19 electrodes we recorded CNVs for mouth opening, closing and lateral movements, tongue protrusion and hand extension in 10 healthy subjects. The aim of the study was to examine the motor control mechanism underlying jaw and tongue movements in a cognitive paradigm. The first stimulus (S1) served as a preparatory warning signal for the imperative stimulus (S2) 2 s after the S1. The subject performed the experimental tasks after the S2. The grand average CNVs for jaw and tongue movements showed a bilaterally widespread negativity with the maximum in the vertex region (Cz). The early CNV was identified about 400 ms after the S1 and its amplitude was highest at the midline-frontal area. The late CNV started approximately 1000 ms after the S1 with the maximum at Cz. The mean amplitude was significantly lower for hand extension than for the other tasks, and significantly higher for lateral movement than for mouth closing, suggesting that the CNV amplitude can be affected by the complexity of the task. The CNV recording may provide a means to study the neuronal activity necessary for the sensorimotor integration of jaw and tongue movements. [source]

Potential Use of Biomarkers in Zooplankton as Early Warning Signals of Ecotoxicological Risk in the Marine Food Chain

Patients' Attitudes Toward Implanted Defibrillator Shocks

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 6 2000
MAHA AHMAD
In addition to its beneficial effect on patient survival, the implanted cardioverter defibriliator (ICD) changes a patient's life physically, socially, and psychologically. For improved patient management, it is important to understand the quality-of-life changes that accompany this mode of treatment. To this end, 119 patients were surveyed retrospectively and interviewed concurrently regarding their emotional, physical, and behavioral responses to ICD shocks and to the device itself. Most (55%) correctly estimated the total number of shocks they had received within a 10% margin. They found the shocks severe, 79% assigning a score between 3 and 5 on a scale of 1,5. Common descriptions of the shock sensation were a blow to the body or a spasm causing the entire body to jump. Most patients tolerated the shocks as life saving, but 23% dreaded shocks and 5% even said they would rather be without the ICD and take their chances. After a shock, 50% of patients called their physician and 42% continued their daily routine. Thirty percent went to a hospital emergency room or called a rescue service. Sixty-five percent had no preshock prodromes. Fifty-four percent were interested in the programmable option of a warning signal prior to a shock, while 31 % preferred no warning. Of the 74% who were advised not to drive after implantation, 29% drove anyway. Five patients were shocked while driving with no resulting accidents. We conclude that most patients find ICD shocks moderately uncomfortable, but they tolerate them because of the lifesaving protection provided by the device. [source]

Locus of the effect of temporal preparation: Evidence from the lateralized readiness potential

PSYCHOPHYSIOLOGY, Issue 4 2003
Hiltraut MÜller-Gethmann
Abstract It is well established that reaction time (RT) is shorter when a response signal is preceded by a warning signal, because the warning signal causes the participant to prepare for the upcoming response. A review of chronometric and psychophysiological studies reveals the prevailing view that this temporal preparation operates mainly at a motor level speeding up rather late processes. To assess the locus of this preparation effect, we conducted two experiments employing the lateralized readiness potential (LRP). Contrary to this prevailing view, the results of both experiments clearly indicate that temporal preparation enhances the processing speed of relatively early processes, because a manipulation of temporal uncertainty affected RT, the P300 latency, and the stimulus-to-LRP interval but not the LRP-to-keypress interval. [source]

Hormonal interplay during adventitious root formation in flooded tomato plants

THE PLANT JOURNAL, Issue 4 2010
Maria Laura Vidoz
Summary Soil flooding, which results in a decline in the availability of oxygen to submerged organs, negatively affects the growth and productivity of most crops. Although tomato (Solanum lycopersicum) is known for its sensitivity to waterlogging, its ability to produce adventitious roots (ARs) increases plant survival when the level of oxygen is decreased in the root zone. Ethylene entrapment by water may represent the first warning signal to the plant indicating waterlogging. We found that treatment with the ethylene biosynthesis inhibitor aminoethoxyvinylglycine (AVG) and the auxin transport inhibitor 1-naphthylphthalamic acid (NPA) resulted in a reduction of AR formation in waterlogged plants. We observed that ethylene, perceived by the Never Ripe receptor, stimulated auxin transport. In a process requiring the Diageotropica gene, auxin accumulation in the stem triggered additional ethylene synthesis, which further stimulated a flux of auxin towards to the flooded parts of the plant. Auxin accumulation in the base of the plant induces growth of pre-formed root initials. This response of tomato plants results in a new root system that is capable of replacing the original one when it has been damaged by submergence. [source]

The role of size and colour pattern in protection of developmental stages of the red firebug (Pyrrhocoris apterus) against avian predators

BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2010
MILENA PROKOPOVÁ
We investigated how predator/prey body-size ratio and prey colour pattern affected efficacy of prey warning signals. We used great and blue tits (Parus major and Cyanistes caeruleus), comprising closely related and ecologically similar bird species differing in body size, as experimental predators. Two larval instars and adults of the unpalatable red firebug (Pyrrhocoris apterus), differing in body size and/or coloration, were used as prey. We showed that prey body size did not influence whether a predator attacked the prey or not during the first encounter. However, smaller prey were attacked, killed, and eaten more frequently in repetitive encounters. We assumed that body size influences the predator through the amount of repellent chemicals better than through the amount of optical warning signal. The larger predator attacked, killed and ate all forms of firebug more often than the smaller one. The difference between both predators was more pronounced in less protected forms of firebug (chemically as well as optically). Colour pattern also substantially affected the willingness of predators to attack the prey. Larval red,black coloration did not provide a full-value warning signal, although a similarly conspicuous red-black coloration of the adults reliably protected them. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 890,898. [source]

Expression of merA, trxA, amoA, and hao in continuously cultured Nitrosomonas europaea cells exposed to cadmium sulfate additions

BIOTECHNOLOGY & BIOENGINEERING, Issue 5 2009
Tyler S. Radniecki
Abstract The effects of CdSO4 additions on the gene expressions of a mercury reductase, merA, an oxidative stress protein, trxA, the ammonia-monooxygenase enzyme (AMO), amoA, and the hydroxylamine oxidoreductase enzyme (HAO), hao, were examined in continuously cultured N. europaea cells. The reactor was fed 50,mM NH4+ and was operated for 78 days with a 6.9 days hydraulic retention time. Over this period, six successive batch additions of CdSO4 were made with increasing maximum concentrations ranging from 1 to 60,µM Cd2+. The expression of merA was highly correlated with the level of Cd2+ within the reactor (Rs,=,0.90) with significant up-regulation measured at non-inhibitory Cd2+ concentrations. Cd2+ appears to target AMO specifically at lower concentrations and caused oxidative stress at higher concentrations, as indicated by the SOURs (specific oxygen uptake rates) and the up-regulation of trxA. Since Cd2+ inhibition is irreversible and amoA was up-regulated in response to Cd2+ inhibition, it is hypothesized that de novo synthesis of the AMO enzyme occurred and was responsible for the observed recovery in activity. Continuously cultured N. europaea cells were more resistant to Cd2+ inhibition than previously examined batch cultured cells due to the presence of Mg2+ and Ca2+ in the growth media, suggesting that Cd2+ enters the cell through Mg2+ and Ca2+ import channels. The up-regulation of merA during exposure to non-inhibitory Cd2+ levels indicates that merA is an excellent early warning signal for Cd2+ inhibition. Biotechnol. Bioeng. 2009; 104: 1004,1011. © 2009 Wiley Periodicals, Inc. [source]

Expression of merA, amoA and hao in continuously cultured Nitrosomonas europaea cells exposed to zinc chloride additions

BIOTECHNOLOGY & BIOENGINEERING, Issue 2 2009
Tyler S. Radniecki
Abstract The effects of ZnCl2 additions on a mercuric reductase, merA, ammonia monooxygenase, amoA, and hydroxylamine (NH2OH) oxidoreductase, hao, gene expression were examined in continuously cultured Nitrosomonas europaea cells. The reactor was operated for 85 days with a 6.9 d hydraulic retention time and with four successive additions of ZnCl2 achieving maximum concentrations from 3 to 90 µM Zn2+. Continuously cultured N. europaea cells were more resistant to Zn2+ inhibition than previously examined batch cultured cells due to the presence of Mg2+ in the growth media, suggesting that Zn2+ enters the cell through Mg2+ import channels. The maximum merA up-regulation was 45-fold and expression increased with increases in Zn2+ concentration and decreased as Zn2+ concentrations decreased. Although Zn2+ irreversibly inactivated ammonia oxidation in N. europaea, the addition of either 600 µM CuSO4 or 2250 µM MgSO4 protected N. europaea from ZnCl2 inhibition, indicating a competition between Zn2+ and Cu2+/Mg2+ for uptake and/or AMO active sites. Since ZnCl2 inhibition is irreversible and amoA was up-regulated at 30 and 90 µM additions, it is hypothesized that de novo synthesis of the AMO enzyme is needed to overcome inhibition. The up-regulation of merA during exposure to non-inhibitory Zn2+ levels indicates that merA is an excellent early warning signal for Zn2+ inhibition. Biotechnol. Bioeng. 2009;102: 546,553. © 2008 Wiley Periodicals, Inc. [source]

An early warning system for detection of financial crisis using financial market volatility

EXPERT SYSTEMS, Issue 2 2006
Kyong Joo Oh
Abstract: This study proposes an early warning system (EWS) for detection of financial crisis with a daily financial condition indicator (DFCI) designed to monitor the financial markets and provide warning signals. The proposed EWS differs from other commonly used EWSs in two aspects: (i) it is based on dynamic daily movements of the financial markets; and (ii) it is established as a pattern classifier, which identifies predefined unstable states in terms of financial market volatility. Indeed it issues warning signals on a daily basis by judging whether the financial market has entered a predefined unstable state or not. The major strength of a DFCI is that it can issue timely warning signals while other conventional EWSs must wait for the next round input of monthly or quarterly information. Construction of a DFCI consists of two steps where machine learning algorithms are expected to play a significant role, i.e. (i) establishing sub-DFCIs on various daily financial variables by an artificial neural network, and (ii) integrating the sub-DFCIs into an integrated DFCI by a genetic algorithm. The DFCI for the Korean financial market is built as an empirical case study. [source]

Characterizing the pigment composition of a variable warning signal of Parasemia plantaginis larvae

Assessing early warning signals of currency crises: a fuzzy clustering approach

INTELLIGENT SYSTEMS IN ACCOUNTING, FINANCE & MANAGEMENT, Issue 4 2006
Shuhua Liu
In the period of 1990s alone, four waves of financial crises occurred around the world. The repeated occurrence of financial crises stimulated a large number of theoretical and empirical studies on the phenomena, in particular studies on the determinants of or early warning signals of financial crises. Nonetheless, the different studies of early warning systems have achieved mixed results and there remains much room for further investigation. Since, so far, the empirical studies have focused on conventional economic modelling methods such as simplified probabilistic models and regression models, in this study we examine whether new insights can be gained from the application of the fuzzy clustering method. The theories of fuzzy sets and fuzzy logic offer us the means to deal with uncertainties inherent in a wide variety of tasks, especially when the uncertainty is not the result of randomness but the result of unknown factors and relationships that are difficult to explain. They also provide us with the instruments to treat vague and imprecise linguistic values and to model nonlinear relationships. This paper presents empirical results from analysing the Finnish currency crisis in 1992 using the fuzzy C-means clustering method. We first provide the relevant background knowledge and introduce the fuzzy clustering method. We then show how the use of fuzzy C-means method can help us to identify the critical levels of important economic indicators for predicting of financial crises. Copyright © 2007 John Wiley & Sons, Ltd. [source]

The information content of option implied volatility surrounding the 1997 Hong Kong stock market crash

THE JOURNAL OF FUTURES MARKETS, Issue 6 2007
Joseph K. W. Fung
This study examines the information conveyed by options and examines their implied volatility at the time of the 1997 Hong Kong stock market crash. The author determines the efficiency of implied volatility as a predictor of future volatility by comparing it to other leading indicator candidates. These include volume and open interest of index options and futures, as well as the arbitrage basis of index futures. Using monthly, nonoverlapping data, the study reveals that implied volatility is superior to those variables in forecasting future realized volatility. The study also demonstrates that a simple signal extraction model could have produced useful warning signals prior to periods of extreme volatility. These results indicate that the options market is highly efficient informationally. © 2007 Wiley Periodicals, Inc. Jrl Fut Mark 27:555,574, 2007 [source]

Country Default Risk: An Empirical Assessment

AUSTRALIAN ECONOMIC PAPERS, Issue 4 2001
Jerome L. Stein
We provide benchmarks to evaluate what is an optimal foreign debt and a maximal foreign debt (debt-max), when risk is explicitly considered. When the actual debt exceeds debt-max, then the economy will default when a ,bad shock' occurs. This paper is an application of the stochastic optimal controls models of Fleming and Stein (2001), which gives empirical content to the question of how one should measure ,vulnerability' to shocks, when there is uncertainty concerning the productivity of capital. We consider two sets of high-risk countries during the period 1978,99: a subset of 21 countries that defaulted on the debt, and another set of 13 countries that did not default. Default is a situation where the firms or government of a country reschedule the interest/principal payments on the external debt. We thereby explain how our analysis can anticipate default risk, and add another dimension to the literature of early warning signals of default/credit risk. [source]

The role of size and colour pattern in protection of developmental stages of the red firebug (Pyrrhocoris apterus) against avian predators

What constitutes optical warning signals of ladybirds (Coleoptera: Coccinellidae) towards bird predators: colour, pattern or general look?

BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2009
MICHAELA DOLENSKÁ
Most ladybirds (Coleoptera: Coccinellidae) possess chemical protection against predators and signal its presence by less or more conspicuous coloration, which can be considered as a warning. Most ladybirds possess a dotted pattern, althougn the number, shape, and size of the spots, as well as their colour, varies considerably. Almost all ladybirds have a characteristic general appearance (body shape). We considered these traits to be used in ladybird recognition by avian predators. In the present study, we compared the reactions of avian predators (Parus major) caught in the wild, to four differently coloured ladybird beetles (Coccinella septempunctata, Exochomus quadripustulatus, Subcoccinella vigintiquatuorpunctata, and Cynegetis impunctata) and two artificial modifications of C. septempunctata; the first was deprived of their elytral spotted pattern by painting it brown, the other had their elytra removed (i.e. altering their general ladybird appearance). Ladybirds with a spotted pattern were attacked less frequently than unspotted ones. Ladybirds with removed elytra were attacked much more often than any ladybird with a preserved general appearance. The results obtained in the present study suggest the high importance of the spotted pattern as well as general appearance in the ladybird recognition process. Additional experiments with naïve birds (hand-reared P. major) demonstrated the innateness of the aversion to two differently spotted ladybird species (C. septempunctata and Scymnus frontalis). © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98, 234,242. [source]

On the clinical relevance of early deficits in critical linguistic functions

ACTA PAEDIATRICA, Issue 12 2005
Francisco Lacerda
Abstract The clinical significance of patterns of deficits in semantic and phonological representations observed by Miniscalco et al. is discussed in light of an ecological approach to language development. Conclusion: Deficits in semantic representations reflect problems in capturing the core linguistic referential function and should be taken as serious early warning signals for language delay. [source]