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Predictable
Terms modified by Predictable Selected AbstractsCUE,REACTIVITY IN RODENTS,HOW PREDICTABLE?ADDICTION, Issue 10 2009MOHAMMED SHOAIB No abstract is available for this article. [source] THE LOCI OF EVOLUTION: HOW PREDICTABLE IS GENETIC EVOLUTION?EVOLUTION, Issue 9 2008David L. Stern Is genetic evolution predictable? Evolutionary developmental biologists have argued that, at least for morphological traits, the answer is a resounding yes. Most mutations causing morphological variation are expected to reside in the cis -regulatory, rather than the coding, regions of developmental genes. This "cis -regulatory hypothesis" has recently come under attack. In this review, we first describe and critique the arguments that have been proposed in support of the cis -regulatory hypothesis. We then test the empirical support for the cis -regulatory hypothesis with a comprehensive survey of mutations responsible for phenotypic evolution in multicellular organisms. Cis -regulatory mutations currently represent approximately 22% of 331 identified genetic changes although the number of cis -regulatory changes published annually is rapidly increasing. Above the species level, cis -regulatory mutations altering morphology are more common than coding changes. Also, above the species level cis -regulatory mutations predominate for genes not involved in terminal differentiation. These patterns imply that the simple question "Do coding or cis -regulatory mutations cause more phenotypic evolution?" hides more interesting phenomena. Evolution in different kinds of populations and over different durations may result in selection of different kinds of mutations. Predicting the genetic basis of evolution requires a comprehensive synthesis of molecular developmental biology and population genetics. [source] Predictable and unpredictable evolution of antibiotic resistanceJOURNAL OF INTERNAL MEDICINE, Issue 1 2008P. Courvalin Abstract. Evolution of bacteria towards antibiotic resistance is unavoidable as it represents a particular aspect of the general evolution of bacteria. Thus, at the very best, the only hope we can have in the field of resistance is to delay dissemination of resistant bacteria or resistance genes. Resistance to antibiotics in bacteria can result from mutations in resident structural or regulatory genes or from horizontal acquisition of foreign genetic information. In this review, we will consider the predictable future of the relationship between bacteria and antibiotics. [source] Optimization of short-term transgene expression by sodium butyrate and ubiquitous chromatin opening elements (UCOEs)THE JOURNAL OF GENE MEDICINE, Issue 8 2007Jolanda J. de Poorter Abstract Background Predictable and adequate transgene expression is essential for clinical gene therapy. Several studies have focused on optimization of transgene expression. In this study the effect of sodium butyrate (NaB) and a ubiquitous chromatin opening element (UCOE) on short-term gene expression after adenovirus-mediated gene transfer in fibroblastic interface cells from periprosthetic tissue in loosened orthopedic implants is investigated. Methods Cultures of diploid human interface cells from four patients were infected with an adenovirus type-5 vector that carries the luciferase gene driven by the cytomegalovirus (CMV) promoter as a reporter. In addition, viruses with a UCOE were evaluated. Twenty-four hours after infection NaB was added in concentrations of 0 to 9 mM. Luciferase activity was tested after a further 24 h. Results NaB in a concentration of 6 mM caused a 7- to 16-fold increase in reporter gene expression compared to control condition. There was no difference in reporter gene expression when cells were infected with Ad.1.5UCOE-CMV.Luc compared to Ad.CMV.Luc. A combination of NaB and a UCOE had no advantage over NaB alone. Conclusions Addition of NaB results in a marked increase in transgene expression in cultured cells. This would allow the enhancement of the expression of the transgene, without requiring a higher vector dose. Butyrate administration could not be substituted by inclusion of UCOEs in the vector. It remains to be established whether the effective concentrations of butyrate can be obtained in vivo. Copyright © 2007 John Wiley & Sons, Ltd. [source] PREDICTING THE IMPACT OF ANTICIPATORY ACTION ON U.S. STOCK MARKET,AN EVENT STUDY USING ANFIS (A NEURAL FUZZY MODEL)COMPUTATIONAL INTELLIGENCE, Issue 2 2007P. Cheng In this study, the adaptive neural fuzzy inference system (ANFIS), a hybrid fuzzy neural network, is adopted to predict the actions of the investors (when and whether they buy or sell) in a stock market in anticipation of an event,changes in interest rate, announcement of its earnings by a major corporation in the industry, or the outcome of a political election for example. Generally, the model is relatively more successful in predicting when the investors take actions than what actions they take and the extent of their activities. The findings do demonstrate the learning and predicting potential of the ANFIS model in financial applications, but at the same time, suggest that some of the market behaviors are too complex to be predictable. [source] Balloon Debanding the Pulmonary Artery: In Vitro Studies and Early Clinical ExperienceCONGENITAL HEART DISEASE, Issue 4 2009Gareth J. Morgan MPhil ABSTRACT Despite increasing corrective procedures for children with congenital heart disease, there remains a place for surgical banding of the main pulmonary artery (PA). In the vast majority of cases, these bands eventually need to be removed. We examined three cases of percutaneous disruption of PA bands using balloon catheters at our institution. We also performed an in vitro study of PA band disruption mechanism and disruption pressure. Our in vitro study suggested a predictable burst pressure for PA bands over the range of diameters routinely used in pediatric practice. Of three patients who underwent interventional debanding, two patients had successful disruption of their PA bands with no reintervention at 19 months and 23 months follow up. Balloon disruption of surgical PA bands may offer a less invasive alternative to surgical band removal. In vitro analysis suggests that the burst pressure required and mechanism of disruption are predictable. [source] A REAPPRAISAL OF THE OVERLAP OF VIOLENT OFFENDERS AND VICTIMS,CRIMINOLOGY, Issue 4 2008CHRISTOPHER J. SCHRECK Because research shows a close association between offending and victimization, recent work has argued that theories that account for crime should explain victimization as well. The current study uses a new approach to examine the extent of the overlap between offenders who commit violent crime and victims of violence to determine whether it is worthwhile to pursue separate theories to account for these phenomena. Specifically, we take the statistical approach that Osgood and Schreck (2007) developed for analyzing specialization in violent versus property offending and apply it to analyzing tendencies to gravitate toward violent offending versus victimization. In doing so, we treat the differentiation into victim and offender roles as an individual-level latent variable while controlling for confounding between the likelihood that individuals will take either role in violent acts and their overall numbers of encounters with violence (as either offender or victim). Our purpose is to examine 1) whether significant differentiation can be observed between the tendency to be an offender versus the tendency to be a victim, 2) whether any such differential tendency is stable over time, and 3) if it is possible to predict whether individuals will tend toward violent offending versus victimization. Using two waves of data from the National Longitudinal Study of Adolescent Health to explore these objectives, we find significant and stable levels of differentiation between offenders and victims. Moreover, this differentiation is predictable with explanatory variables. [source] Fate of developing tooth buds located in relation to mandibular fractures in three infancy casesDENTAL TRAUMATOLOGY, Issue 4 2010Kazuhiko Yamamoto Three infants, 2 girls and a boy, aged from 1 year and 5-months old to 2 years and 6-months old, were treated for dislocated mandibular fracture in the symphyseal region by manual reduction and fixation with a thermoforming splint and circumferential wiring under general anesthesia. Fracture healing was uneventful in all cases. A few years later, no obvious deformity of the jaw or malocclusion was observed; however, malformation of the crown was found in one of the permanent teeth on the fracture line in the first case. In the second case, no abnormality was observed in one of the permanent teeth on the fracture line, but the effect on the other tooth could not be evaluated due to abnormality of the tooth probably not related to the injury. In the third case, root formation was arrested in one of the permanent teeth on the fracture line and the tooth was lost early after eruption. The development of tooth buds on the fracture line is not predictable and therefore, should be monitored by regular follow up. [source] The evolution of depression and suicidality in first episode psychosisACTA PSYCHIATRICA SCANDINAVICA, Issue 3 2010R. Upthegrove Upthegrove R, Birchwood M, Ross K, Brunett K, McCollum R, Jones L. The evolution of depression and suicidality in first episode psychosis. Objective:, To have a clearer understanding of the ebb and flow of depression and suicidal thinking in the early phase of psychosis, whether these events are predictable and how they relate to the early course of psychotic symptoms. Method:, Ninety-two patients with first episode psychosis (FEP) completed measures of depression, including prodromal depression, self-harm and duration of untreated psychosis. Follow-up took place over 12 months. Results:, Depression occurred in 80% of patients at one or more phases of FEP; a combination of depression and suicidal thinking was present in 63%. Depression in the prodromal phase was the most significant predictor of future depression and acts of self-harm. Conclusion:, Depression early in the emergence of a psychosis is fundamental to the development of future depression and suicidal thinking. Efforts to predict and reduce depression and deliberate self-harm in psychosis may need to target this early phase to reduce later risk. [source] Results of a Survey of 5,700 Patient Monopolar Radiofrequency Facial Skin Tightening Treatments: Assessment of a Low-Energy Multiple-Pass Technique Leading to a Clinical End Point AlgorithmDERMATOLOGIC SURGERY, Issue 8 2007FRCP, FRCPC, JEFFREY S. DOVER MD INTRODUCTION Monopolar radiofrequency is an effective means of nonsurgical facial skin tightening. OBJECTIVE The objective of this study was to determine whether using larger tips at lower energy and multiple passes, using patient feedback on heat sensation and treating to a clinical end point of visible tightening, would yield better results than single passes with small tips at high energy, as measured by patient and physician satisfaction. METHODS Fourteen physicians from four specialties were surveyed to determine the answers to the following three questions. (1) Is patient's feedback on heat sensation a valid and preferred method for optimal energy selection? (2) Do multiple passes at moderate energy settings yield substantial and consistent efficacy? (3) Is treating to a clinical end point of visible tightening predictable of results? RESULTS A total of 5,700 patient treatments were surveyed. Comparisons were made using the original algorithm of high-energy, single pass to the new algorithm of lower energy and multiple passes with visible tightening as the end point of treatment. Using the original treatment algorithm, 26% of patients demonstrated immediate tightening, 54% observed skin tightening 6 months after treatment, 45% found the procedure too painful, and 68% of patients found the treatment results met their expectations. With the new multiple-pass algorithm, 87% observed immediate tightening, 92% had the tightening six months after treatment, 5% found the procedure too painful, while 94% found the treatment results met their expectations. CONCLUSIONS Patient feedback on heat sensation is a valid, preferable method for optimal energy selection in monopolar radiofrequency skin-tightening treatments. [source] Sentinel Lymph Node Biopsy for High-Risk Nonmelanoma Skin CancersDERMATOLOGIC SURGERY, Issue 7 2007RACHEL E. SAHN BACKGROUND Although the utility of the sentinel lymph node biopsy (SLNB) in the staging of melanoma is well established, its usefulness in high-risk nonmelanoma skin cancer (NMSC) is yet to be determined. OBJECTIVE The objective was to report our experience with patients who underwent SLNB for the staging of a high-risk NMSC. MATERIALS AND METHODS We identified 13 patients with a high-risk NMSC who underwent SLNB between 1998 and 2006 and conducted a retrospective review of their medical records and tumor pathology. Their status as regards tumor recurrence and survival was obtained when possible. RESULTS Of 13 patients, 9 had squamous cell carcinoma (SCC), 2 had sebaceous gland carcinoma, 1 had porocarcinoma, and 1 had atypical fibroxanthoma. All SLNB were negative for metastatic disease, but 1 appeared to be a false-negative finding. CONCLUSION Compared to melanoma, SCC of the skin are much less predictable as regards their tendency to metastasize to the regional lymph nodes. Although the SLNB appears to be a reliable staging procedure for NMSC (especially SCC), the yield may be too low to justify its routine use in this patient population. More data are needed to determine when a SLNB is justified in the management of NMSC. [source] Soft tissue augmentation 2006: filler fantasyDERMATOLOGIC THERAPY, Issue 3 2006Arnold William Klein ABSTRACT:, As an increasing number of patients seek esthetic improvement through minimally invasive procedures, interest in soft tissue augmentation and filling agents is at an all-time high. One reason for this interest is the availability of botulinum toxin type A, which works superbly in the upper face. The rejuvenation of the upper face has created much interest in injectable filling agents and implant techniques that work equally well in the restoration of the lower face. One of the central tenets of soft tissue augmentation is the concept of the three-dimensional face. The youthful face has a soft, full appearance, as opposed to the flat, pulled, two-dimensional look often achieved by more traditional surgical approaches. Injectable filling agents can augment and even at times, replace pulling. Additionally, with the lip as the focal center of the lower face, subtle lip enhancement is here to stay, and is in fact, the number one indication for injectable fillers. Moreover, minimally invasive soft tissue augmentation offers cosmetic enhancement without the cost and recovery time associated with more invasive procedures. As more and more physicians take interest in minimally invasive surgery, courses in cosmetic surgery techniques are becoming increasingly popular at the medical meetings of many specialties. Today, physicians have a much larger armamentarium of techniques and materials with which to improve facial contours, ameliorate wrinkles, and provide esthetic rejuvenation to the face. For a substance or device to be amenable for soft tissue augmentation in the medical community, it must meet certain criteria. It must have both a high "use" potential, producing cosmetically pleasing results with a minimum undesirable reactions, and have a low abuse potential in that widespread or incorrect or indiscriminate use would not result in significant morbidity. It must be nonteratogenic, noncarcinogenic, and nonmigratory. In addition, the agent must provide predictable, persistent correction through reproducible implantation techniques. Finally, the substance, agent or device must be approved by the U.S. Food and Drug Administration, which assures purity, safety, and accessibility, as well as much-needed information regarding use. Having a thorough understanding of the filling agents available, their indications and contraindications, as well as having thorough knowledge of implant technique are vital in providing the patient with an esthetically pleasing result. [source] The Politics of Disciplining Water RightsDEVELOPMENT AND CHANGE, Issue 2 2009Rutgerd Boelens ABSTRACT This article examines how the legal systems of Andean countries have dealt with the region's huge plurality of local water rights, and how official policies to ,recognize' local rights and identities harbour increasingly subtle politics of codification, confinement and disciplining. The autonomy and diversity of local water rights are a major hindrance for water companies, elites and formal rule-enforcers, since State and market institutions require a predictable, uniform playing field. Complex local rights orders are seen as irrational, ill-defined and disordered. Officialdom cannot simply ignore or oppress the ,unruliness and disobedience' of local rights systems: rather it ,incorporates' local normative orders that have the capacity to adequately respond to context-based needs. This article examines a number of evolving, overlapping legal domination strategies, such as the ,marrying' of local and official legal systems in ways that do not challenge the legal and power hierarchy; and reviews the ways in which official regulation and legal strategies deny or take into consideration local water rights repertoires, and the politics of recognition that these entail. Post-colonial recognition policies are not simply responses to demands by subjugated groups for greater autonomy. Rather, they facilitate the water bureaucracy's political control and help neoliberal sectors to incorporate local water users' rights and organizations into the market system , even though many communities refuse to accept these policies of recognition and politics of containment. [source] IMF Gold and the World Bank's Unfunded HIPC DeficitDEVELOPMENT POLICY REVIEW, Issue 1 2004Jonathan E. Sanford The World Bank is to forgive $12.24 billion in IDA debt payments from HIPC borrowers. It has received $1 billion from the HIPC Trust Fund to help offset these losses, but still has a $11.6 billion unfunded liability. The IMF has gold worth $38 billion on hand for which it has no actual use. This article proposes that a small portion of IMF gold be sold annually, just enough to offset IDA's annual HIPC deficit, over the next twenty years. The new money would be additional and predictable, and would eliminate the prospect that IDA would have to cut back its future flow of aid because the HIPC programme had drained its resources. [source] Stress experienced in utero reduces sexual dichotomies in neurogenesis, microenvironment, and cell death in the adult rat hippocampusDEVELOPMENTAL NEUROBIOLOGY, Issue 5 2008Chitra D. Mandyam Abstract Hippocampal function and plasticity differ with gender, but the regulatory mechanisms underlying sex differences remain elusive and may be established early in life. The present study sought to elucidate sex differences in hippocampal plasticity under normal developmental conditions and in response to repetitive, predictable versus varied, unpredictable prenatal stress (PS). Adult male and diestrous female offspring of pregnant rats exposed to no stress (control), repetitive stress (PS-restraint), or a randomized sequence of varied stressors (PS-random) during the last week of pregnancy were examined for hippocampal proliferation, neurogenesis, cell death, and local microenvironment using endogenous markers. Regional volume was also estimated by stereology. Control animals had comparable proliferation and regional volume regardless of sex, but females had lower neurogenesis compared to males. Increased cell death and differential hippocampal precursor kinetics both appear to contribute to reduced neurogenesis in females. Reduced local interleukin-1beta (IL-1,) immunoreactivity (IR) in females argues for a mechanistic role for the anti-apoptotic cytokine in driving sex differences in cell death. Prenatal stress significantly impacted the hippocampus, with both stress paradigms causing robust decreases in actively proliferating cells in males and females. Several other hippocampal measures were feminized in males such as precursor kinetics, IL-1,-IR density, and cell death, reducing or abolishing some sex differences. The findings expand our understanding of the mechanisms underlying sex differences and highlight the critical role early stress can play on the balance between proliferation, neurogenesis, cell death, and hippocampal microenvironment in adulthood. © 2008 Wiley Periodicals, Inc. Develop Neurobiol, 2008. [source] Treatment of symptomatic diabetic neuropathyDIABETES/METABOLISM: RESEARCH AND REVIEWS, Issue S1 2003Andrew J. M. Boulton Abstract Painful diabetic neuropathy is a common and particularly unpleasant long-term complication of diabetes that affects a significant minority of patients with distal polyneuropathy. After exclusion of other causes of neuropathic pain, attention should be focused on achieving optimal and stable glycaemic control avoiding flux of blood glucose levels, which have been shown to aggravate pain. Most patients will require pain control therapy and whilst the tricyclic drugs remain a first-line approach, their use is often hampered by predictable but troublesome side effects. Gabapentin, the only agent specifically licensed for the treatment of neuropathic pain in the United Kingdom, is useful in diabetic neuropathy and is generally better tolerated than the tricyclics. Additionally, other pharmacological and non-pharmacological pain management approaches may be useful. Patient education has a significant role to play in the avoidance of late neurological complications. Copyright © 2003 John Wiley & Sons, Ltd. [source] Glucose sensors: a review of current and emerging technologyDIABETIC MEDICINE, Issue 3 2009N. S. Oliver Abstract Glucose monitoring technology has been used in the management of diabetes for three decades. Traditional devices use enzymatic methods to measure glucose concentration and provide point sample information. More recently continuous glucose monitoring devices have become available providing more detailed data on glucose excursions. In future applications the continuous glucose sensor may become a critical component of the closed loop insulin delivery system and, as such, must be selective, rapid, predictable and acceptable for continuous patient use. Many potential sensing modalities are being pursued including optical and transdermal techniques. This review aims to summarize existing technology, the methods for assessing glucose sensing devices and provide an overview of emergent sensing modalities. [source] Soil creep and convex-upward velocity profiles: theoretical and experimental investigation of disturbance-driven sediment transport on hillslopesEARTH SURFACE PROCESSES AND LANDFORMS, Issue 13 2004Joshua J. Roering Abstract The movement of unconsolidated materials near the Earth's surface is often driven by disturbances that occur at a range of spatial and temporal scales. The nature of these disturbances ranges from highly variable, such as tree turnover, to periodic and predictable, such as frost heave or creep. To explore the effect of probabilistic disturbances on surface processes, we formulated a granular creep model with analogy to rate process theory (RPT) used for chemical reactions. According to the theory, individual particles must be energized to a height greater than adjacent particles in order for grain dilation and transport to occur. The height of neighbouring particles (which is akin to activation energy in chemical reactions) varies with slope angle such that energy barriers get smaller in the downslope direction as slopes steepen. When slopes approach the friction-limited angle of repose, the height of energy barriers approaches zero and grains ,ow in the absence of disturbance. An exponential function is used to describe the probability distribution of particle excitation height although alternative distributions are possible. We tested model predictions of granular dynamics in an experimental sandpile. In the sandpile, acoustic energy serves as the disturbance agent such that grains dilate and shear in response. Particle velocities are controlled by the frequency of energy pulses that result in grain displacement. Using tracer particles, we observed a convex-upward velocity pro,le near the surface of the sandpile, consistent with predictions of our RPT-based velocity model. In addition, we depth-integrated the velocity model to predict how ,ux rates vary with inclination of the sandpile and observed non-linear ,ux,gradient curves consistent with model predictions. By varying the acoustic energy level in the experimental sandpile, we documented changes in the rate of grain movement; similar changes in modelled velocities were achieved by varying the exponent of the particle excitation probability distribution. The general agreement between observed and modelled granular behaviour in our simple laboratory sandpile supports the utility of RPT-based methods for modelling transport processes (e.g. soil creep, frost heave, and till deformation), thus enabling us to account for the probabilistic nature of disturbances that liberate sediment in natural landscapes. Copyright © 2004 John Wiley & Sons, Ltd. [source] Spherical sliding isolation bearings with adaptive behavior: Experimental verificationEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 2 2008Daniel M. Fenz Abstract This paper describes an experimental program to examine the force,displacement behavior of a class of multi-spherical sliding bearings. The primary goal of the experiments is to test the validity of the theory developed in a companion paper that describes the behavior of these devices. Experimental work consisted of testing the three primary variations of these bearings in several configurations of different friction and displacement capacities. Most tests were carried out at slow speeds; however, some testing was also conducted at high speed (up to approximately 400,mm/s) to examine the behavior under dynamic conditions. The results of experimental testing were generally found to be in very good agreement with the analytical results. It is shown that the forces and displacements at which transitions in stiffness occur are predictable and therefore controllable in design. Furthermore, the underlying principles of operation were confirmed by the fact that starting and stopping of sliding on the different surfaces occurred as expected from theory. Copyright © 2007 John Wiley & Sons, Ltd. [source] Sexual patterns of prebreeding energy reserves in the common frog Rana temporaria along a latitudinal gradientECOGRAPHY, Issue 5 2009K. Ingemar Jönsson The ability to store energy is an important life history trait for organisms facing long periods without energy income, and in particular for capital breeders such as temperate zone amphibians, which rely on stored energy during reproduction. However, large scale comparative studies of energy stores in populations with different environmental constraints on energy allocation are scarce. We investigated energy storage patterns in spring (after hibernation and before reproduction) in eight common frog Rana temporaria populations exposed to different environmental conditions along a 1600,km latitudinal gradient across Scandinavia (range of annual activity period is 3,7,months). Analyses of lean body weight (eviscerated body mass), weight of fat bodies, liver weight, and liver fat content, showed that 1) post-hibernation/pre-breeding energy stores increased with increasing latitude in both sexes, 2) males generally had larger energy reserves than females and 3) the difference in energy stores between sexes decreased towards the north. Larger energy reserves towards the north can serve as a buffer against less predictable and/or less benign weather conditions during the short activity period, and may also represent a risk-averse tactic connected with a more pronounced iteroparous life history. In females, the continuous and overlapping vitellogenic activity in the north may also demand more reserves in early spring. The general sexual difference could be a consequence of the fact that, at the time of our sampling, females had already invested their energy into reproduction in the given year (i.e. their eggs were already ovulated), while the males' main reproductive activities (e.g. calling, mate searching, sexual competition) occurred later in the season. [source] Macroecology of a host-parasite relationshipECOGRAPHY, Issue 1 2000Caryn C. Vaughn The larvae of freshwater mussels are obligate ectoparasites on fishes while adults are sedentary and benthic. Dispersal of mussels is dependent on the movement of fish hosts, a regional process, but growth and reproduction should be governed by local processes. Thus, mussel assemblage attributes should be predictable from the regional distribution and abundance of fishes. At a broad spatial scale in the Red River drainage, USA, mussel species richness and fish species richness were positively associated; maximum mussel richness was limited by fish richness, but was variable beneath that constraint. Measured environmental variables and the associated local fish assemblages each significantly accounted for the regional variation in mussel assemblages. Furthermore, mussel assemblages showed strong spatial autocorrelation. Variation partitioning revealed that pure fish effects accounted for 15.4% of the variation in mussel assemblages; pure spatial and environmental effects accounted for 16.1% and 7.8%, respectively. Shared variation among fish, space and environmental variables totaled 40%. Of this shared variation, 36.8% was associated with the fish matrix. Thus, the variation in mussel assemblages that was associated with the distribution and abundance of fishes was substantial (> 50%), indicating that fish community structure is an important determinant of mussel community structure. Although animals commonly disperse plants and, thus, influence the structure of plant communities, our results show a strong macroecological association between two disparate animal groups with one strongly affecting the assemblage structure of the other. [source] Contrasting seasonal dynamics in fleas of the Siberian flying squirrel (Pteromys volans) in FinlandECOLOGICAL ENTOMOLOGY, Issue 4 2007VOITTO HAUKISALMI Abstract 1.,The seasonal and spatial variation of the adult flea fauna (Siphonaptera) was examined in connection with live-trapping studies of the Siberian flying squirrel (Pteromys volans) in three study areas in southern Finland between 1997 and 2005. 2.,The numerically dominant flea species of the Siberian flying squirrel were Tarsopsylla octodecimdentata octodecimdentata and Ceratophyllus (Monopsyllus) indages indages (Ceratophyllidae); the latter being a host specialist of the Siberian flying squirrel. Tarsopsylla octodecimdentata, which also commonly occurs on the red squirrel (Sciurus vulgaris), infected a large proportion of the host population throughout the winter, whereas C. indages occurred predominantly during the summer and autumn, being practically the only flea species in nests during the flying squirrels' breeding season and on juveniles still inhabiting their natal nest. 3.,The use of nest boxes by flying squirrels did not have any positive effects on flea populations, but it may have had a negative impact on T. octodecimdentata. 4.,The potentially vulnerable C. i. indages is a predictable, widespread component in the flea fauna of the Siberian flying squirrel at various spatial scales, and it is likely to occur in most of the permanent flying squirrel populations in Finland. [source] Melanism in a larval Lepidoptera: repeatability and heritability of a dynamic traitECOLOGICAL ENTOMOLOGY, Issue 2 2006Kwang Pum Lee Abstract., 1.,Although it is well established that the deposition of melanin pigment in the cuticle of larval Lepidoptera is influenced by both environmental and genetic factors, few studies have examined intra-individual regional variation in the degree of melanism or the ontogenetic dynamics of this trait. Here, heritable and density-dependent effects on within-individual and stage-specific variation in melanism were examined in caterpillars of the Egyptian cotton leafworm, Spodoptera littoralis (Boisduval). 2.,Using quantitative spectrometric methods, it is shown that cuticular melanism changes dramatically within larval stadia, showing the highest and lowest levels of melanism early (first day) and late (final day) in each larval stadium respectively. However, solitary-reared caterpillars were significantly paler than those reared gregariously at all stages of development and maintained greater levels of variation in melanism. This variation in melanism was repeatable and exhibited a significant heritable component (narrow sense heritability based on offspring,parent regressions: h2 = 0.18,0.30). 3.,The degree of melanism was correlated negatively with larval body weight in solitary caterpillars, but not gregarious ones. Melanism also varied spatially, with the lateral longitudinal band being consistently darker than the dorsal or dorso-lateral bands. Crowd-rearing increased melanism in all regions of larval cuticle, but the extent of crowding-induced melanism was more pronounced in the dorsal and dorso-lateral bands than in the lateral one. 4.,These results indicate that although cuticular melanism is a highly dynamic trait, ontogenetic changes in relative cuticular melanism are both predictable and repeatable within individuals and genotypes. This has implications for our understanding of the evolution of melanism and for applying artificial selection on the basis of colour. [source] Community effects of praying mantids: a meta-analysis of the influences of species identity and experimental designECOLOGICAL ENTOMOLOGY, Issue 4 2002William F. Fagan Abstract ,1. Generalist arthropod predators are ubiquitous in terrestrial ecosystems but experimental studies have yielded little agreement as to their effects on prey assemblages. Drawing on results from a suite of experimental field studies, a meta-analysis was conducted of the impact of praying mantids (Mantodea: Mantidae) on arthropod assemblages in order to identify predictable and unpredictable effects of these extremely generalised predators. 2. Results across different experiments were synthesised using the log response ratio framework, with a focus on quantifying net mantid impacts on arthropod density across taxonomic orders and trophic levels of arthropods, paying special attention to the contribution of mantid species identity and experimental design variables, such as the use of cages, length of experiment, and manipulated mantid density. 3. Calculated on a per mantid-day basis, the net impacts of Tenodera sinensis on arthropod density were generally weaker but more predictable than the effects of Mantis religiosa. Mantids in general had weak negative effects on density for most taxa but exhibited strong negative and positive effects on some taxa. Tenodera sinensis tended to have negative effects on Homoptera, Diptera, and Hemiptera and herbivores as a group, however M. religiosa exhibited greater variation in response of different taxa that appeared to be affected more strongly by experimental design. The effects of Stagmomantis carolina tended to be negative or non-significant. 4. Experimental cages had little influence on either the sign or magnitude of net community impacts for T. sinensis, however cage experiments reversed the sign of the mean effect for two of six taxonomic orders when the experimental predator was M. religiosa. Cages also increased the variability of effect size greatly for M. religiosa but not for T. sinensis. 5. It was concluded that it is possible to use log response ratios to determine general, predictable trends in a well-studied system. Similar meta-analyses of generalist predator effects in other systems should produce predictions of how these predators influence food webs, an important step towards defining more clearly the influences of generalist predators on community structure and dynamics. [source] Mass regulation in response to predation risk can indicate population declinesECOLOGY LETTERS, Issue 10 2007Ross MacLeod Abstract In theory, survival rates and consequent population status might be predictable from instantaneous behavioural measures of how animals prioritize foraging vs. avoiding predation. We show, for the 30 most common small bird species ringed in the UK, that one quarter respond to higher predation risk as if it is mass-dependent and lose mass. Half respond to predation risk as if it only interrupts their foraging and gain mass thus avoiding consequent increased starvation risk from reduced foraging time. These mass responses to higher predation risk are correlated with population and conservation status both within and between species (and independently of foraging habitat, foraging guild, sociality index and size) over the last 30 years in Britain, with mass loss being associated with declining populations and mass gain with increasing populations. If individuals show an interrupted foraging response to higher predation risk, they are likely to be experiencing a high quality foraging environment that should lead to higher survival. Whereas individuals that show a mass-dependent foraging response are likely to be in lower quality foraging environments, leading to relatively lower survival. [source] Importance of species interactions to community heritability: a genetic basis to trophic-level interactionsECOLOGY LETTERS, Issue 1 2006Joseph K. Bailey Abstract Recent community genetics studies have shown that specific genotypes of a host plant support distinct arthropod communities. Building upon these findings, we examined the hypothesis that a trophic community consisting of cottonwood trees, a galling herbivore and avian predators could also be related to the genetics of the host tree. We found genetic correlations among phytochemistry of individual tree genotypes, the density of a galling herbivore, and the intensity of avian predation on these herbivores. We detected significant broad-sense heritability of these interactions that range from H = 0.70 to 0.83. The genetic basis of these interactions tended to increase across trophic levels suggesting that small genetic changes in the cottonwood phenotype could have major consequences at higher trophic levels affecting species interactions and energy flow. These findings show a heritable basis to trophic-level interactions indicating that there is a significant genetic basis to community composition and energy flow that is predictable by plant genotype. Our data clearly link plant genetics to patterns of avian foraging and show that species interactions are important components of community heritability and ecosystem processes. Overall, these data support the hypothesis that evolution of plant traits can alter trophic-level interactions and community composition. [source] Transfer of endophyte-origin defensive alkaloids from a grass to a hemiparasitic plantECOLOGY LETTERS, Issue 12 2005Päivi Lehtonen Abstract Plants growing in natural environments experience myriad interactions with a diverse assemblage of pathogens, parasites and mutualists. Many of these interactions involve symbiotic bacteria and fungi, but they also include macroparasitic plants. In this study, we investigated the interactions among a host grass (Lolium pratense, ex., Festuca pratensis), its symbiotic endophytic fungus (Neotyphodium uncinatum), a root hemiparasitic plant (Rhinanthus serotinus) of the host grass and a generalist herbivore (aphid Aulacorthum solani) of the hemiparasite. We demonstrate that the hemiparasitic plant acquires defending mycotoxins produced by the endophytic fungus living within their shared host grass. The uptake of defensive mycotoxins from the endophyte-infected host grass enhances the resistance of the hemiparasitic plant to the generalist aphid herbivore. Endophyte infection increases the performance of the hemiparasitic plant, but reduces the growth of the host grass. In other words, the mutualistic endophytic fungus becomes parasitic in the presence of the hemiparasitic plant. Our results suggest that the outcomes of grass,endophyte interactions are conditional on the complexity of community-level interactions; thus, the outcome of multispecies interactions may not be predictable from pair-wise combinations of species. [source] Advancing Loss Given Default Prediction Models: How the Quiet Have QuickenedECONOMIC NOTES, Issue 2 2005Greg M. Gupton We describe LossCalcÔ version 2.0: the Moody's KMV model to predict loss given default (LGD), the equivalent of (1 , recovery rate). LossCalc is a statistical model that applies multiple predictive factors at different information levels: collateral, instrument, firm, industry, country and the macroeconomy to predict LGD. We find that distance-to-default measures (from the Moody's KMV structural model of default likelihood) compiled at both the industry and firm levels are predictive of LGD. We find that recovery rates worldwide are predictable within a common statistical framework, which suggests that the estimation of economic firm value (which is then available to allocate to claimants according to each country's bankruptcy laws) is a dominant step in LGD determination. LossCalc is built on a global dataset of 3,026 recovery observations for loans, bonds and preferred stock from 1981 to 2004. This dataset includes 1,424 defaults of both public and private firms , both rated and unrated instruments , in all industries. We demonstrate out-of-sample and out-of-time LGD model validation. The model significantly improves on the use of historical recovery averages to predict LGD. [source] Liquidity Constraints and Firms' Investment Return BehaviourECONOMICA, Issue 276 2002Parantap Basu We construct a production-based model, which compares the investment return behaviour of liquidity-constrained firms with that of unconstrained firms. The key testable implication that emerges from the model is that the investment returns of the constrained firms are predictable, while those of the unconstrained firms are not. We test this implication indirectly, verifying whether the capital stock and investment returns of the latter firms lead those of the former, and directly, via the estimation of an Euler equation. Our results are consistent with the model's prediction. [source] Mixture and single-substance toxicity of selective serotonin reuptake inhibitors toward algae and crustaceansENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2007Anne Munch Christensen Abstract Selective serotonin reuptake inhibitors (SSRIs) are used as antidepressant medications, primarily in the treatment of clinical depression. They are among the pharmaceuticals most often prescribed in the industrialized countries. Selective serotonin reuptake inhibitors are compounds with an identical mechanism of action in mammals (inhibit reuptake of serotonin), and they have been found in different aqueous as well as biological samples collected in the environment. In the present study, we tested the toxicities of five SSRIs (citalopram, fluoxetine, fluvoxamine, paroxetine, and sertraline) as single substances and of citalopram, fluoxetine, and sertraline in binary mixtures in two standardized bioassays. Test organisms were the freshwater algae Pseudokirchneriella subcapitata and the freshwater crustacean Daphnia magna. In algae, test median effect concentrations (EC50s) ranged from 0.027 to 1.6 mg/L, and in daphnids, test EC50s ranged from 0.92 to 20 mg/L, with sertraline being one of the most toxic compounds. The test design and statistical analysis of results from mixture tests were based on isobole analysis. It was demonstrated that the mixture toxicity of the SSRIs in the two bioassays is predictable by the model of concentration addition. Therefore, in risk assessment based on chemical analysis of environmental samples, it is important to include the effect of all SSRIs that are present at low concentrations, and the model of concentration addition may be used to predict the combined effect of the mixture of SSRIs. [source] | ||||||||||||||||||||||||||||||||||||||||