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PubMed2002

Premonitory patterns of seismicity months before a large earthquake: five case histories in Southern California.

This article explores the problem of short-term earthquake prediction based on spatio-temporal variations of seismicity. Previous approaches to this problem have used precursory seismicity patterns that precede large earthquakes with "intermediate" lead times of years. Examples include increases of earthquake correlation range and increases of seismic activity. Here, we look for a renormalization of these patterns that would reduce the predictive lead time from years to months. We demonstrate a combination of renormalized patterns that preceded within 1-7 months five large (M > or = 6.4) strike-slip earthquakes in southeastern California since 1960. An algorithm for short-term prediction is formulated. The algorithm is self-adapting to the level of seismicity: it can be transferred without readaptation from earthquake to earthquake and from area to area. Exhaustive retrospective tests show that the algorithm is stable to variations of its adjustable elements. This finding encourages further tests in other regions. The final test, as always, should be advance prediction. The suggested algorithm has a simple qualitative interpretation in terms of deformations around a soon-to-break fault: the blocks surrounding that fault began to move as a whole. A more general interpretation comes from the phenomenon of self-similarity since our premonitory patterns retain their predictive power after renormalization to smaller spatial and temporal scales. The suggested algorithm is designed to provide a short-term approximation to an intermediate-term prediction. It remains unclear whether it could be used independently. It seems worthwhile to explore similar renormalizations for other premonitory seismicity patterns.

Journal Article↗
PubMed2006

Bone remodelling inside a cemented resurfaced femoral head.

BACKGROUND: Although the short-term performance of modern resurfacing hip arthroplasty is impressive, the long-term performance is still unknown. It is hypothesised that bone remodelling and the resulting changes in stress/strain distribution within the resurfaced femur influence the risk of fixation failure. METHOD: Three-dimensional finite element models and adaptive bone remodelling algorithms have been used to predict long-term changes in bone density following cemented femoral head resurfacing. Applied loading conditions include normal walking and stair climbing. The remodelling simulation was validated by comparing the results of an analysis of a proximal femur implanted with a Charnley femoral component with known clinical data in terms of bone density adaptations. FINDINGS: Resurfacing caused a reduction of strain of 20-70% in the bone underlying the implant as compared to the intact femur, immediately post operative. Elevated strains, ranging between 0.50 and 0.80% strain, were generated post-operatively around the proximal femoral neck regions, indicating a potential risk of neck fracture. However, this strain concentration was considerably reduced after bone remodelling. After remodelling, bone resorption of 60-90% was observed in the bone underlying the implant. Reduction in bone density of 5-47% occurred in the lateral femoral head. Bone apposition was observed in the proximal-medial cortex, around the inferior edge of the implant. Hardly any changes in bone density occurred in the distal neck or the femoral diaphysis. INTERPRETATION: Although resurfacing has produced encouraging clinical results, bone remodelling within the femoral head might be a concern for long-term fixation. Regions of strain concentration at the head-neck junction, which may increase the initial risk of femoral neck fracture, are reduced with bone remodelling. In order to reduce this risk of femoral neck fracture, patients should avoid activities which induce high loading of the hip during the early rehabilitation period after surgery.

Bone Cements↗
PubMed2004

Externalizing problem behaviors and headache: a follow-up study of adolescent Finnish twins.

OBJECTIVE: To examine the association of teacher- and parent-rated behavior with headache in a prospective follow-up study of adolescent Finnish twins. METHODS: Questionnaire data were collected during 1995-2001 from a nationwide sample of Finnish families of 11-year-old twins who were born 1983-1987 (n = 5393) and again at age of 14. Psychological factors were measured by using parents' and teachers' ratings of a 37-item multidimensional rating instrument at the ages of 11 and 14. RESULTS: At age 11, headache frequency (5 categories) was associated with total scales of externalizing and internalizing problem behaviors and adaptive behaviors, assessed by parents, but only with externalizing problem behaviors assessed by teachers. Results were similar at age 14. The incidence of at least monthly headache between the ages of 11 and 14 years was predicted by externalizing problem behaviors and 2 subscales of adaptive behaviors: constructiveness and poor compliance. In twin pairs discordant for headache, externalizing and internalizing problem behaviors were more common among headache sufferers than among headache-nonsufferers. Headache-discordant monozygotic co-twins confirmed the association of externalizing problem behaviors with headache. CONCLUSIONS: The frequency of adolescents' headache is predicted by psychological factors, especially by externalizing problem behaviors. This seems to be independent of genetic or familial influences on behavior and headache. Behavioral problems may be a sign of worsening of headache or vice versa.

Adolescent↗
PubMed1999

Nonlinear alteration of transient vergence dynamics after sustained convergence.

BACKGROUND: Adaptation models of the horizontal disparity vergence system assume a nonadaptable transient component. They also predict identical postadaptation dynamics during convergence and divergence movements. METHOD: To test the adaptation property of the transient component, a set of experiments were performed in which closed-loop vergence dynamics measured before and after sustained convergence were compared, primarily by comparing the peak vergence velocity, occurrence time of peak vergence velocity, and steady-state vergence posture. Vergence dynamics after durations of 30, 60, and 90 s of sustained convergence were compared with those after a control duration of 5 s. RESULTS: The peak divergence velocity was reduced by about 25% within 30 s of sustained vergence. However, the peak convergence velocity was unchanged for all the exposure durations. Additionally, for all durations, the peak divergence velocity was significantly higher than peak convergence velocity. In contrast to peak velocities, the occurrence time of peak convergence and divergence velocity did not differ significantly and remained unchanged for all durations. CONCLUSIONS: The transient component is adaptable. Furthermore, the adaptation is direction dependent and affects divergence and convergence dynamics differently, thereby suggesting involvement of separate pathways for convergence and divergence in the vergence sensorimotor control.

Accommodation, Ocular↗
PubMed2003

Glucagon-like peptide-2 and intestinal adaptation: an historical and clinical perspective.

Of the many models of intestinal adaptation, the structural and functional changes seen in the residual small bowel following jejunectomy or ileectomy are the most predictable and best studied. There are three major mechanisms for these adaptive phenomena: changes in i) luminal nutrition, ii) pancreatico-biliary secretions and iii) hormonal factors. Observations in a unique patient with an "enteroglucagon"-secreting tumor of the kidney associated with massive small bowel enlargement, provided the strongest evidence, at that time (>30 y ago), in favor of hormonal factors. When the patient's renal tumor was removed, the markedly increased circulating concentrations of the glucagon-like peptide (now presumed to be GLP-2) returned to normal-as did her intestinal anatomy. Subsequent studies showed that there are increased tissue and plasma enteroglucagon (and recently GLP-2) levels in many animal models of intestinal adaptation. This, and anecdotal evidence from three other case reports, coupled with contemporary studies of GLP-2, strongly suggest that this glucagon-like peptide is a potent, but not the sole, enterotrophin.

Adaptation, Physiological↗
PubMed2006

Translational proteomics: developing a predictive capacity -- a review.

Over the past decade, proteomics has undergone a rapid development and radiation, diversifying across the biochemical landscape. While no single technique yet delivers complete proteomic coverage, application-specific adaptations afford significant opportunity for discovery and the development of predictive capacity (e.g. surrogate biomarker and clinical diagnostics). Targeted proteomic approaches, protein profiling strategies using affinity capture mass spectrometry and solution array represent realistic opportunities to deliver predictive capacity. The aim of this review is to provide an overview of proteomic technologies and how the outcomes delivered by such platforms may be translated into applications of predictive utility in clinical and basic science. In particular, recent applications in protein/peptide profiling (solid-phase affinity capture mass spectrometry and the targeted approach of antibody arrays) and the opportunities they afford researchers within the discipline of reproductive biology to develop new diagnostic and prognostic tests and surrogate biomarkers to improve the delivery of women's health care are considered.

Animals↗
PubMed1999

Plasticity of feedback inputs in the apteronotid electrosensory system.

Weakly electric fish generate an electric field surrounding their body by means of an electric organ typically located within the trunk and tail. Electroreceptors scattered over the surface of the body encode the amplitude and timing of the electric organ discharge (EOD), and central components of the electrosensory system analyze the information provided by the electroreceptor afferents. The electrosensory system is used for electrolocation, for the detection and analysis of objects near the fish which distort the EOD and for electrocommunication. Since the electric organ is typically located in the tail, any movement of this structure relative to the rest of the body alters the EOD field, resulting in large changes in receptor afferent activity. The amplitude of these reafferent stimuli can exceed the amplitudes of near-threshold electrolocation signals by several orders of magnitude. This review summarizes recent studies of the South American weakly electric fish Apteronotus leptorhynchus aimed at determining how the animals differentiate self-generated or reafferent electrosensory stimuli from those that are more behaviorally relevant. Cells within the earliest stages of central electrosensory processing utilize an adaptive filtering technique which allows the system preferentially to attenuate reafferent as well as other predictable patterns of sensory input without degrading responses to more novel stimuli. Synaptic plasticity within the system underlies the adaptive component of the filter and enables the system to learn to reject new stimulus patterns if these become predictable. A Ca2+-mediated form of postsynaptic depression contributes to this synaptic plasticity. The filter mechanism seen in A. leptorhynchus is surprisingly similar to adaptive filters described previously in mormyrid weakly electric fish and in elasmobranchs, suggesting that this mechanism may be a common feature of sensory processing systems.

Animals↗
PubMed1998

The genetics of Alzheimer disease: current status and future prospects.

Four genes involved in the development of Alzheimer disease have been identified. Three fully penetrant (deterministic) genes lead to the development of Alzheimer disease in patients younger than 60 years: the amyloid beta-protein precursor on chromosome 21, presenilin 1 on chromosome 14, and presenilin 2 on chromosome 1. Together, they account for about half of this early-onset form of the disease. One genetic risk factor--apolipoprotein E-4--is associated with late-onset Alzheimer disease. It accounts for a substantial fraction of disease burden but seems to act primarily to lower the age of disease onset. In general, none of these genes can be easily adapted for use as a diagnostic or predictive test for Alzheimer disease. Research activity includes searching for additional genes, especially for late-onset disease, and elucidating the mechanism of action of all identified genes as part of a long-term effort to develop more effective therapeutic and preventive strategies.

Alzheimer Disease↗
PubMed1999

Geographical variation in temporal and spatial vocalization patterns of male harbour seals in the mating season.

In the aquatically mating harbour seal, Phoca vitulina, oestrous females show marked differences in spatial and temporal distribution between geographical areas. This suggests that the males' display behaviour may also vary between areas. We recorded male vocalizations in two areas, the Moray Firth and Orkney, U.K. In the Moray Firth, females haul out on a few intertidal sandbars and travel along predictable routes to forage at sea. In Orkney, female haul out sites are much less influenced by tidal availability and females are much more dispersed. In the Moray Firth, males vocalized only during a short mating season, from 1 July to 12 August. Vocalizations varied significantly with the tide, the peak at high tide clearly coinciding with the period when most females were in the water. In contrast, vocalizations in Orkney were significantly related to both tidal and diel patterns. We suggest that the timing of male vocalizations reflects differences in female availability between sites. In the inner Moray Firth, vocalizations were heard throughout the females' range, whereas vocalizations in Orkney were heard only in two discrete areas. However, at both sites the density of vocalizing males was highest in narrow channels and/or along predictable female travel routes. Therefore, males clearly adapt their temporal and spatial behaviour patterns to variations in female distribution and density. These results suggest that male mating strategies in aquatically mating pinnipeds are more variable than was previously envisaged. Copyright 1999 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed2002

Group formation games with reappraisal.

The formation of a social group, such as the group of individuals sharing a territory, depends on the interaction between choices made by individuals to stay or disperse. The process can be modelled as a multi-player variant of the well-known War of Attrition in evolutionary game theory, as shown by Blackwell (1997; J. Theor. Biol.189, 175-181). In this paper, we extend the set of strategies defined there by allowing reappraisal during the game. We give a formal analysis of the evolutionarily stable strategy, where one exists, and illustrate it with an example based on badger (Meles meles) territoriality. The results predict that group size will be well adapted to, and very sensitive to, the precise conditions under which the game is played, and give an indication of the potential for parent-offspring conflict.

Animals↗
PubMed2006

Tall herb herbivory resistance reflects historic exposure to leaf beetles in a boreal archipelago age-gradient.

In this paper, we introduce the coevolution-by-coexistence hypothesis which predicts that the strength of a coevolutionary adaptation will become increasingly apparent as long as the corresponding selection from an interacting counterpart continues. Hence, evolutionary interactions between plants and their herbivores can be studied by comparing discrete plant populations with known history of herbivore colonization. We studied populations of the host plant, Filipendula ulmaria (meadow sweet), on six islands, in a Bothnian archipelago subject to isostatic rebound, that represent a spatio-temporal gradient of coexistence with its two major herbivores, the specialist leaf beetles Galerucella tenella and Altica engstroemi. Regression analyses showed that a number of traits important for insect-plant interactions (leaf concentrations of individual phenolics and condensed tannins, plant height, G. tenella adult feeding and oviposition) were significantly correlated with island age. First, leaf concentrations of condensed tannins and individual phenolics were positively correlated with island age, suggesting that plant resistance increased after herbivore colonization and continued to increase in parallel to increasing time of past coexistence, while plant height showed a reverse negative correlation. Second, a multi-choice experiment with G. tenella showed that both oviposition and leaf consumption of the host plants were negatively correlated with island age. Third, larvae performed poorly on well-defended, older host populations and well on less-defended, younger populations. Thus, no parameter assessed in this study falsifies the coevolution-by-coexistence hypothesis. We conclude that spatio-temporal gradients present in rising archipelagos offer unique opportunities to address evolutionary interactions, but care has to be taken as abiotic (and other biotic) factors may interact in a complicated way.

Animals↗
PubMed1986

Restricted feeding and circadian activity rhythms of a predatory marsupial, Dasyuroides byrnei.

There is considerable disagreement as to whether food availability entrains circadian activity rhythms in omnivorous laboratory rodents. However, in carnivorous mammals a restricted feeding regime could act as a zeitgeber because the predator should hold a periodism correlated to that of the prey. Nevertheless, a restricted feeding schedule does not dominate the LD cycle for entrainment of circadian activity rhythms of the nocturnal predator Dasyuroides byrnei, nor does it entrain the free-running activity rhythms in DD. Anticipatory wheel running prior to food availability was observed in most animals. Some evidence for weak coupling between LD-entrained and meal-associated oscillators was indicated by occurrences of relative coordination. This species does not appear to have a dominance hierarchy of zeitgebern different to that reported for laboratory rodents. One would have predicted that it would have been ecologically adaptive for cycles of food availability to be more important than the LD cycle in this species.

Animals↗
PubMed2004

Annals of the ICRP. A report of: doses to infants from ingestion of radionuclides in mothers' milk.

In the present report, ICRP provides information on radiation doses to the infant due to intakes of radionuclides in maternal milk. As in Publication 88 (ICRP, 2001) on doses to the embryo and fetus following intakes of radionuclides by the mother, intakes by female members of the public and female workers are addressed. Acute and chronic intakes are considered at various times before and during pregnancy as well as during the period of breastfeeding. Dose coefficients per unit intake by the mother (Sv/Bq) are given for the selected radionuclides of the same 31 elements for which age-specific biokinetic models were given in Publications 56, 67, 69, and 71 (ICRP, 1989, 1993, 1995a,b). For these elements, doses were calculated for the most radiologically significant natural or artificial radionuclides that might be released into the environment due to various human activities. Dose coefficients are also given in this report for radionuclides of an additional four elements: sodium, magnesium,phosphorus, and potassium. Relevant human and animal data on elemental and radionuclide transfer to milk are reviewed. The biokinetic models for adults given in earlier ICRP publications are adapted to include transfer to milk. Model predictions of fractional transfer of ingested or inhaled activity to milk are discussed in the report, and the corresponding dose coefficients for the infant are compared with dose coefficients for in utero exposure, as given in Publication 88 (ICRP, 2001). Illustrative information is also given on doses to the female breast from radionuclides in breastmilk, and external doses received by the child from radionuclides retained in the tissues of the mother. For the additional elements considered in this report, but not in Publication 88 (ICRP,2001), information is also given on doses to the embryo and fetus following maternal intakes of radioisotopes during or before pregnancy. A CD-ROM is to be issued giving data that will supplement the information given in this report. In addition to the dose coefficients given here, committed equivalent doses to the various organs and tissues of the offspring will be given. Dose coefficients will also be given for inhalation of a range of aerosol sizes for the selected radionuclides of the elements covered by this report.

Female↗
PubMed2026

Genome-wide identification of the carotenoid cleavage dioxygenase gene family in wheat and analysis of the TaDREB-7A-TaNCED9a regulatory module conferring drought tolerance.

Carotenoid cleavage dioxygenases (CCDs) play critical roles in plant growth, development, and abiotic stress responses, yet their genome-wide identification and drought response mechanisms remain unexplored in wheat. In this study, 34 TaCCD genes were identified in wheat, distributed across 15 chromosomes and phylogenetically classified into five subfamilies. Gene structure analysis indicated that members within each subfamily shared conserved motifs and similar intron-exon arrangements. Cis-regulatory element analysis suggested the potential roles of these genes in stress adaptation, developmental processes, and hormone signaling. Moreover, prediction of tertiary structures and protein-protein interactions revealed unique structural features and potential interacting partners of the TaCCD proteins. In addition, TaNCED9a, a member of the TaCCD family, showed the highest transcript level in wheat roots among all detected TaCCD genes and was significantly induced by drought stress. Subcellular localization assay indicated that TaNCED9a was located in chloroplasts. Downregulation of TaNCED9a expression led to reduced drought resistance in wheat, accompanied by an accumulation of reactive oxygen species and a decrease in endogenous abscisic acid levels. Using yeast one-hybrid, dual-luciferase, and tobacco transient co-expression assays, the upstream regulatory factor TaDREB-7A was identified, which can regulate the expression of TaNCED9a. Additionally, a KASP molecular marker was developed to identify the superior haplotype TaNCED9a-HapI, which exhibited a significantly higher germination rate compared to TaNCED9a-HapII under drought conditions, and was predominant in wheat. These results offer valuable insights into the TaCCD gene family's response mechanisms to drought stress in wheat, simultaneously identifying promising genetic resources for enhancing drought tolerance through molecular breeding.

CCD↗
PubMed2005

Large shifts in perceived motion direction reveal multiple global motion solutions.

Moving objects are thought to be decomposed into one-dimensional motion components by early cortical visual processing. Two rules describing how these components might be re-combined to produce coherent object motion are the intersection of constraints and the vector average rules. Using stimuli for which these combination rules predict different directional solutions, we found that adapting one of the solutions through motion adaptation switched perceived direction to the other solution. The effects were symmetrical: shifts from IOC to VA, and from VA to IOC, were observed following adaptation. These large shifts indicate that multiple solutions to global motion processing coexist and compete to determine perceived motion direction.

Adaptation, Psychological↗
PubMed2006

Short- and long-term variations of norovirus concentrations in the Meuse river during a 2-year study period.

Faecally impacted surface waters used for drinking water production may encompass risk for norovirus infections. To be able to assess a possible health risk, noroviruses should be quantified and fluctuations identified. In 2001, norovirus concentrations in the river Meuse displayed a seasonal distribution with high peaks during wintertime as determined by RT-PCR on serially diluted RNA. An intensified day-by-day sampling scheme in the winter of 2002/2003 revealed that the winter peak consisted of several peaks of varying duration and magnitude, possibly due to contamination events in the catchment. The highest estimated concentration was 1700 PCR-detectable units per litre (95% CI 250-8000), which if coinciding with failing treatment could lead to significant numbers in drinking water. Adaptive dynamic filtering was shown to adequately predict subsequent sample concentrations. If valid, such analyses could prove to be useful as early warning systems in risk management of water sources.

Netherlands↗
PubMed2003

Regulation of the ABA-sensitive Arabidopsis potassium channel gene GORK in response to water stress.

The phytohormone abscisic acid (ABA) regulates many stress-related processes in plants. In this context ABA mediates the responsiveness of plants to environmental stresses such as drought, cold or salt. In response to water stress, ABA induces stomatal closure by activating Ca2+, K+ and anion channels in guard cells. To understand the signalling pathways that regulate these turgor control elements, we studied the transcriptional control of the K+ release channel gene GORK that is expressed in guard cells, roots and vascular tissue. GORK transcription was up-regulated upon onset of drought, salt stress and cold. The wilting hormone ABA that integrates responses to these stimuli induced GORK expression in seedlings in a time- and concentration-dependent manner and this induction was dependent on extracellular Ca2+. ABA-responsive expression of GORK was impaired in the ABA-insensitive mutants abi1-1 and abi2-1, indicating that these protein phosphatases are regulators of GORK expression. Application of ABA to suspension-cultured cells for 2 min followed by a 4 h chase was sufficient to manifest transcriptional activation of the K+ channel gene. As predicted for a process involved in drought adaptation, only 12-24 h after the release of the stress hormone, GORK mRNA slowly decreased. In contrast to other tissues, GORK expression as well as K+(out) channel activity in guard cells is ABA insensitive, allowing the plant to adjust stomatal movement and water status control separately.

Abscisic Acid↗
PubMed2001

Improved process control alarm operation.

Alarms are the main connection from the automation to the operator, when addressing process operation outside of its normal function. They are often as much a source of operator overload and consternation as help. Better engineering of the relative role of the operator and automation would materially help overcome the difficulties. Expert systems have been proposed as a solution. But Expert systems are really another form of automation. There remains that aspect of the alarms, which must address our inability to cover and understand a possibly larger domain of the operation not appropriate to traditional controls or present-day automation. Appropriate tools for this domain must support operator discretion and initiative. The paper suggests a set of such general, computer science based, tools requiring only the most basic configuration. They are viewed as implemented on top of those properly detailed alarm displays and interlocks, which reflect the more formal plant operating policies. They include: (a) Various forms of alarm logging and trending; (b) Short, automatically generated, word summaries of alarm activity, which allow low level data to propagate to the highest levels, including: one word and priority summaries; (c) Causal alarm pattern analyses that help the operator to predict or diagnose alarm behavior; (d) Automatic adaptation of alarms and alarm limits to varying process situations; (e) Uniform use of alarm policies to simplify alarm configuration.

Journal Article↗