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Aggressiveness
Kinds of Aggressiveness Selected AbstractsDO FEMALE SPIDERS SELECT HEAVIER MALES FOR THE GENES FOR BEHAVIORAL AGGRESSIVENESS THEY OFFER THEIR OFFSPRING?EVOLUTION, Issue 6 2003S. E. RIECHERT Abstract., We explore the hypothesis that females choose to mate with heavier males for the genes for behavioral aggressiveness they offer their offspring in the desert spider, Agelenopsis aperta. Behavioral aggressiveness is important to competition for limited resources in the field and is thus correlated with the mass spiders achieve. We established four crosses based on the body mass relationships of parents subjected to selection in their natural environment (female mass/male mass: HI/HI, HI/LO, LO/HI, and LO/LO) and reared the F1 offspring in a noncompetitive laboratory environment. Offspring size and mass at maturity were measured, life history parameters recorded, and behavioral aggressiveness scored in a series of tests. Significant familial effects were detected in all of these measures, but pertinent cross effects were observed only in the assays measuring behavioral aggressiveness. The results were summarized in terms of the fitness costs to HI females of mating with LO males (fewer female offspring of the more aggressive phenotypes) and the benefits to LO females of mating with HI males (fewer fearful offspring of both sexes). [source] Letter: Re: Insufficient Aggressiveness with Tumescent Suction CurettageDERMATOLOGIC SURGERY, Issue 3 2009FIACS, LAWRENCE M. FIELD MD No abstract is available for this article. [source] Ring chromosome 20 syndrome with intractable epilepsyDEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 5 2005Asude Alpman MD Ring chromosome 20 (r[20]) syndrome is characterized by mild to moderate learning disability*, behavioural disorders, epilepsy, and various dysmorphic features. Although still considered rare, r(20) syndrome is being increasingly diagnosed. More than 30 cases have been described in the literature since 1976. Here we report an additional case of a 14-year-old male with r(20). He had moderate to severe learning disability and epileptic seizures manifesting at about 18 months of age. During the 13 years' follow-up period he showed intractable epileptic seizures, behavioural disorders, and mild dysmorphological features including microcephaly, strabismus, micrognathia, down-slanting eyelids, and ear abnormalities. Frequent episodes of atypical absence or non-convulsive status associated with electroencephalogram changes were seen in follow-up. He was treated with several classical and new antiepileptic drugs, including intravenous immunoglobulin, corticotropin, and vagal nerve stimulation, with unsuccessful control of seizures. Finally, surgical treatment (corpus callosotomy) was performed at the age of 13 years; severity of tonic seizures was diminished, but frequency was unchanged. Although his behavioural problems, e.g. hyperactivity, were mild in early childhood they became more severe when he was 11 years old. Aggressiveness, compulsiveness with self-injury, and panic attacks developed at the age of 13 years, and were more pronounced after callosotomy. This case report provides the first description of deterioration in psychological situation in patients with r(20) intractable epilepsy. The patient was diagnosed with r(20) syndrome after 13 years of clinical follow-up. Karyotype analysis should, therefore, be performed in every patient with intractable epilepsy of unknown aetiology. [source] Does Host Value Influence Female Aggressiveness, Contest Outcome and Fitness Gain in Parasitoids?ETHOLOGY, Issue 4 2007Marlene Goubault Intraspecific competition for resources is common in animals and may lead to physical contests. Contest outcomes and aggressiveness can be influenced by the resource holding potential of contestants but also by their perception of the resource value (RV). Competitors may assess resource quality directly (real RV) but may also estimate it according to their physiological status and their experience of the habitat quality (subjective RV). In this article, we studied contests between females of the solitary parasitoid Pachycrepoideus vindemmiae Rondani (Hymenoptera: Pteromalidae) when exploiting simultaneously a host, a Delia radicum L. (Diptera: Anthomyiidae) pupa. We tested the effect of factors modifying host value on the occurrence of agonistic behaviours, contest outcomes and host exploitation. The factors tested were: the quality of the previous habitat experienced by females, female egg load, host parasitism status and the stage reached by the owner female in her behavioural oviposition sequence. Females successfully protected their host against intruders during its exploitation, but not after oviposition, and their aggressiveness did not seem to be influenced by their perception of the RV. The fact that the host is subsequently parasitized by the opponent females appears to mainly depend on the host selectiveness of females. [source] Mothers' Trait Verbal Aggressiveness as a Predictor of Maternal and Child Behavior During Playtime InteractionsHUMAN COMMUNICATION RESEARCH, Issue 3 2008Steven R. Wilson This article explores associations between mothers' trait verbal aggressiveness (VA) and maternal and child behavior during playtime interactions. Forty mothers completed a 10-minute play period with one of their children (range = 3,8 years) and then responded to D. A. Infante and C. J. Wigley's (1986) trait VA scale. Mothers' trait VA was associated positively (r = .48) with their rate of directing and inversely (r =,.44) with their child's rated cooperation. Qualitative analyses of a subset (n = 8) of interactions suggest that mothers high in trait VA used directives to control the choice, rate, and duration of activities, and used physical negative touch along with directives, more than low-VA mothers. Behaviors associated with trait VA occur even during brief mother,child interactions in which triggers for aggressive behavior largely are absent. Résumé Le trait d,agressivité verbale des mères comme variable explicative des comportements maternels et infantiles lors d'interactions de jeu Cet article explore les associations entre le trait d,agressivité verbale (AV) des mères et le comportement maternel et infantile lors d'interactions de jeu. 40 mères ont participéà une période de jeu de 10 minutes avec l,un de leurs enfants (tranche d'âge = 3-8 ans) puis ont répondu à l'échelle de trait d'AV d,Infante et Wigley (1986). Le trait d'AV des mères fut associé positivement (r= 0,48) à leur taux de contrôle et inversement (r= -0,44) au taux de coopération de leur enfant. Des analyses qualitatives d,un sous-ensemble (n= 8) d'interactions donnent à penser que les mères au trait d,AV élevé ont fait usage de directives pour contrôle le choix, le rythme et la durée des activités et qu'elles ont utilisé le toucher physique négatif en même temps que les directives, plus que ne l,ont fait les mères au trait d'AV faible. Les comportements associés au trait d'AV surviennent même lors de brèves interactions mère-enfant au cours desquelles les déclencheurs de comportements agressifs étaient largement absents. Abstract Das Müttermerkmal verbale Aggression als Prädiktor für Mutter-Kind-Verhalten in spielerischen Interaktionen Dieser Artikel untersucht den Zusammenhang zwischen dem Müttermerkmal verbale Aggression (VA) und dem Mutter-Kind-Verhalten in spielerischen Interaktionen. 40 Mütter spielten 10 Minuten lang mit einem ihrer Kinder (zwischen 3-8 Jahren) und beantworteten dann die VA-Eigenschaftsskala nach Infante & Wigley (1986). Das Müttermerkmal VA war positiv assoziiert (r= .48) mit der Häufigkeit des führenden Eingreifens und umgekehrt assoziiert (r= -.44) mit der vom Kind beurteilten Kooperation. Qualitative Analysen eines Teils (n= 8) der Interaktionen deuten darauf hin, dass Mütter mit hoher VA führendes Eingreifen nutzen, um die Wahl, Häufigkeit und Dauer von Aktivitäten zu kontrollieren. Sie nutzten außerdem häufiger physisch negative Berührungen zusammen mit dem führenden Eingreifen als Mütter mit niedriger VA. Mit dem Merkmal VA verbundene Verhaltensweisen finden sogar in kurzen Mutter-Kind-Interaktionen statt bei denen Auslöser für aggressives Verhalten weitestgehend fehlen. Resumen El Rasgo de la Agresividad Verbal de las Madres como Vaticinador del Comportamiento Materno y del Niño Durante las Interacciones en el Recreo Este artículo explora la asociación entre el rasgo de agresividad verbal de las madres (VA) y el comportamiento maternal y del niño durante las interacciones en el recreo. Cuarenta madres completaron un período de 10-minutos de juego con uno de sus hijos (oscilando = 3-8 años) y luego respondieron a la escala sobre el rasgo VA de Infante y Wigley (1986). El rasgo VA de las madres fue asociado positivamente (r= .48) con el grado de direccionamiento e inversamente (r= -.44) con el grado de cooperación de su niño. Los análisis cualitativos de un subset (n= 8) de interacciones sugieren que las madres con rasgos altos de VA usaron directivas para controlar la selección, el tipo, y la duración de las actividades, y usaron el contacto físico negativo junto con directivas, más que las madres con rasgos bajos de VA. Los comportamientos asociados con el rasgo VA durante las interacciones breves entre la madre y su niño que provocan el comportamiento agresivo se encuentran mayormente ausentes. ZhaiYao Yo yak [source] Childhood Personality Predicts Long-Term Trajectories of Shyness and Aggressiveness in the Context of Demographic Transitions in Emerging AdulthoodJOURNAL OF PERSONALITY, Issue 1 2008Jaap J. A. Dennissen ABSTRACT In a 19-year longitudinal study, childhood personality characteristics (assessed by teachers at ages 4 to 6) were significantly related to both initial levels and changes in parental judgments of shyness and aggressiveness. Long-term stability was demonstrated by the fact that overcontrollers had consistently higher scores in shyness and undercontrollers in aggressiveness. However, undercontrollers' shyness and overcontrollers' aggressiveness changed over time from a low to a high level. Also, both types assumed adult social roles, such as leaving the parental home, establishing a first romantic relationship, and getting a part-time job, at a later time than the resilient participants. A mediation analysis indicated that under- and overcontrollers' increasing aggressiveness between age 17 and 23 was due to their longer latency of getting a part-time job. Together, results demonstrate the importance of considering person-environment transactions in explaining both change and stability in personality between childhood and adulthood. [source] Variation in Aggressiveness of Stagonospora nodorum Isolates in North DakotaJOURNAL OF PHYTOPATHOLOGY, Issue 3 2008S. Ali Abstract Stagonospora nodorum blotch (SNB), caused by Stagonospora nodorum, is an important disease in the northern Great Plains of the United States and in other wheat-producing regions in the world. SNB can be managed by different strategies including the use of resistant cultivars. Genetic variation in the pathogen populations is one of the important factors in the development of durable resistant cultivars. Our main objective was to determine variation in aggressiveness/virulence in the 40 isolates of S. nodorum collected from various locations in North Dakota. To achieve this goal, we tested the isolates on two susceptible wheat cultivars (cvs ,ND495' and ,Alsen') and two resistant wheat cultivars (cvs ,Erik' and ,Salamouni') , two-leaf-stage seedlings under controlled conditions. Aggressiveness of each isolate was characterized by the two epidemiological parameters: percent necrotic leaf area (% NLA) and lesion type (LT) 8 days post-inoculation. The isolates differed significantly (P , 0.05) for % NLA and LT, and were grouped into three aggressiveness groups (AG): low, medium and highly aggressive. Four isolates (S50, S57, S66 and S89) induced 18,26% NLA and were included into the low aggressive group (AG 1). Three isolates (S15, S39 and S89) induced 57,59% NLA and were considered highly aggressive (AG 3). Thirty-three isolates were medium aggressive (AG 2). No relationship between AG and mating types was observed. There were significant (P , 0.05) differences in % NLA and LT among wheat cultivars. Significant wheat cultivars by isolates interaction was also demonstrated, suggesting evidence for the existence of host specificity in this system. Overall, our results indicate that S. nodorum isolates prevalent in North Dakota varied greatly in their aggressiveness and that AG 3 isolates can be utilized in breeding wheat for resistance to SNB. [source] Incidence, Aggressiveness and In Planta Interactions of Botrytis cinerea and other Filamentous Fungi Quiescent in Grape Berries and Dormant Buds in Central Washington StateJOURNAL OF PHYTOPATHOLOGY, Issue 7 2002F. M. Dugan Abstract Recovery of quiescent filamentous fungi from non-symptomatic grape berries and dormant buds demonstrated dominance of Alternaria, Aureobasidium, Cladosporium, Ulocladium and other dematiaceous hyphomycetes. Up to 78% of berries contained fungi prior to harvest. Botrytis cinerea was recovered from 0.2 to 0.5% of surface-disinfested berries just subsequent to fruit set, and 1.6,4.8% of surface-disinfested, over-wintered dormant buds. In laboratory inoculations of mature grape berries with strains of Alternaria, Aureobasidium, Cladosporium, Ulocladium and Botrytis, only the latter was aggressive in rotting berry fruits. Inoculations with B. cinerea alone and in combination with strains of Alternaria, Aureobasidium, Cladosporium and Ulocladium recovered from grape demonstrated that prior occupation of wound sites by the latter fungi resulted in reduced lesion size compared to inoculation with B. cinerea alone. [source] Fusarium culmorum Infection of Barley Seedlings: Correlation between Aggressiveness and Deoxynivalenol ContentJOURNAL OF PHYTOPATHOLOGY, Issue 6 2002HELLE HESTBJERG Fusarium culmorum is a serious plant pathogen, especially on cereals. The production of deoxynivalenol (DON) by F. culmorum is believed to play a role in pathogenesis. This relationship has been almost exclusively studied in connection with head blight. The present paper reports the first finding of DON in cereal seedlings infected with F. culmorum. A pathogenicity test was performed, including 70 isolates of this pathogen from different sites within northern and central Europe. All isolates caused disease on barley seedlings. For 15 isolates with varying aggressiveness, the DON content in the 19-day-old-barley seedlings was determined. There was a significant correlation between DON concentration and disease index. The aggressiveness of two outlying isolates with very low DON production is discussed. The results indicate that for F. culmorum isolates of the DON chemotype, production of this toxin influences the aggressiveness of the isolates towards barley seedlings. [source] Aggressiveness is associated with genetic diversity in landlocked salmon (Salmo salar)MOLECULAR ECOLOGY, Issue 9 2003Katriina Tiira Abstract The amount of intraindividual genetic variation has often been found to have profound effects on life history traits. However, studies concerning the relationship between behaviour and genetic diversity are scarce. Aggressiveness is an important component of competitive ability in juvenile salmonids affecting their later performance and survival. In this study, we used an experimental approach to test the prediction that juveniles with low estimated genetic diversity should be less aggressive than juveniles with high estimated genetic diversity in fry from a highly endangered population of land-locked salmon (Salmo salar). This was achieved by using a method enabling the accurate estimation of offspring genetic diversity based on parental microsatellite genotype data. This allowed us to create two groups of offspring expected to have high or low genetic diversity in which aggressive behaviour could be compared. Salmon fry with low estimated genetic diversity were significantly less aggressive than fry with high estimated genetic diversity. Closer analysis of the data suggested that this difference was due to differences in more costly acts of aggression. Our result may reflect a direct effect of genetic variation on a fitness-related trait; however, we cannot rule out an alternative explanation of allele-specific phenotype matching, where lowered aggression is expressed towards genetically more similar individuals. [source] Aggressiveness of Phytophthora infestans and phenotypic analysis of resistance in wild Petota accessions in EcuadorPLANT PATHOLOGY, Issue 4 2007M. G. Chacón The aggressiveness of four Phytophthora infestans isolates collected from wild and cultivated potato species (sect. Petota) and the level of resistance of nine Petota species were assessed in the highland tropics of Ecuador. For this, isolates of P. infestans were inoculated on whole plants of Petota species in the field and net house and six epidemiological components , infection frequency (IF), incubation period (IP), latent period (LP), lesion size (LS), lesion growth rate (LGR), and relative area under the lesion expansion curve (RAULEC) , were measured during a single infection cycle. Additionally, host specificity was determined by testing for a significant host by pathogen interaction using the same components. The results showed significant differences among isolates of the EC-1 clonal lineage for IP, IF, and RAULEC. Significant differences among isolates were not found for the other components measured. There were significant differences in resistance among the accessions of Petota hosts tested. RAULEC, LGR, LP, and LS were in general more adequate in differentiating among the more resistant and more susceptible accessions but the importance of each component varied with host species. There was slight and inconsistent evidence for the existence of host specificity in some isolates of Petota hosts. IP was the only component for which a significant host by isolate interaction was observed and in most cases the isolates had the greatest aggressiveness on their hosts of origin. [source] Sympatric ascochyta complex of wild Cicer judaicum and domesticated chickpeaPLANT PATHOLOGY, Issue 3 2007O. Frenkel The aim of this study was to isolate, identify and characterize ascochyta blight pathogens from Cicer judaicum, a wild annual Cicer species which grows in Israel and other Mediterranean countries in sympatric distribution with legume crops, and determine their virulence and aggressiveness to other wild and domesticated legumes. Native C. judaicum plants exhibited symptoms resembling ascochyta diseases of grain legume crops. Two distinct pathogens were isolated and identified as Phoma pinodella and Didymella rabiei using morphological and molecular tools; their infectivity was verified using Koch's postulates. The virulence of these pathogens was examined on 13 legume species, of which P. pinodella was virulent to Pisum sativum, P. fulvum, C. judaicum, C. arietinum, C. reticulatum, C. pinnatifidum and C. bijugum. Didymella rabiei infected all these Cicer species, but not the other legume species tested. Aggressiveness of the pathogens was tested on wild and domesticated chickpea and pea. Didymella rabiei isolated from C. judaicum had significantly higher (P < 0·001) aggressiveness than P. pinodella from C. judaicum on both wild and domesticated chickpea. Disease severity on the former species ranged from 62·5% to 70% and on the latter from 41% to 56%. Phoma pinodella isolates from C. judaicum were more aggressive on C. arietinum and P. sativum than on C. judaicum and P. fulvum. Results of the current study suggest that C. judaicum may serve as an alternative host to ascochyta pathogens that endanger chickpea and possibly other crops and wild species growing in close proximity. [source] Aggressiveness and Quantification of Epithelial Proliferation of Middle Ear Cholesteatoma by MIB1THE LARYNGOSCOPE, Issue 2 2003Y. Mallet MD Abstract Objective To assess an easy method that predicts cholesteatoma aggressiveness. Study Design An experimental prospective study. Methods Monoclonal antibody MIB1 was used to determine epithelium proliferation in 91 cholesteatomatous ears. Clinical and surgical parameters were compared with proliferation activity to determine pathological and clinical correlation. Results Statistical correlations were established between hyperproliferation of the cholesteatoma and severe bone erosion (leading to major cholesteatoma complications) and between hyperproliferation and middle ear inflammation (associated with more surgical difficulties and a higher risk of recurrence). A high proliferation index was also found in children's cholesteatoma, which is known to have more aggressive behavior. Conclusion Immunohistochemical use of the MIB1 antibody is a simple technique that can help to determine the aggressiveness of a cholesteatoma. [source] A behavioural syndrome in the field cricket Gryllus integer: intrasexual aggression is correlated with activity in a novel environmentBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 3 2007RAINE KORTET Behavioural syndromes, or suites of correlated behaviours across different contexts and situations, have recently drawn attention from evolutionary biologists. In the field cricket Gryllus integer, males are aggressive with one another and fight vigorously over females and territories. We examined whether aggressiveness with other males was correlated with activity in a potentially dangerous context (a novel environment) in laboratory-raised virgin males. Aggressiveness was measured as fighting ability against a weight-matched opponent. First, we measured each cricket's latency to become active in a novel environment and latency to emerge from a refuge within a novel environment. Next, we determined which of two weight-matched males was more aggressive, by pitting the males together in an agonistic contest and counting the number of fights won by each male. More aggressive males, who won more fights, had shorter latencies to become active when placed in a novel environment and shorter latencies to emerge from a safe refuge. These results suggest that a behavioural syndrome exists in G. integer, in which more aggressive males are also more active in general, and possibly less cautious towards predation risk. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 91, 475,482. [source] Earnings Management and Corporate Governance in Asia's Emerging MarketsCORPORATE GOVERNANCE, Issue 5 2007Chung-Hua Shen This paper studies the impacts of corporate governance on earnings management. We use firm-level governance data, taken from Credit Lyonnais Security Asia (CLSA), of nine Asian countries, in addition to the country-level governance data used in past studies. Our conclusion is as follows. First, firms with good corporate governance tend to conduct less earnings management. Second, there is a size effect for earnings smoothing, that is, large size firms are prone to conduct earnings smoothing, but good corporate governance can mitigate the effect on average. Third, there is a turning point for leverage effect, i.e. when the governance index is large, leverage effect exists, otherwise reverse leverage effect exists. It shows that a highly leveraged firm with poor governance is prone to be scrutinised closely and thus finds it harder to fool the market by manipulating earnings. Fourth, firms with higher growth (lower earnings yield) are prone to engage in earnings smoothing and earnings aggressiveness, but good corporate governance can mitigate the effect. Finally, firms in stronger anti-director rights countries tend to exhibit stronger earnings smoothing. This counter-intuitive result is different from Leuz et al. (2003). [source] Childhood predictors of adult criminality: are all risk factors reflected in childhood aggressiveness?CRIMINAL BEHAVIOUR AND MENTAL HEALTH, Issue 3 2002L. Rowell Huesmann Background Early aggressive behaviour is one of the best predictors of adult criminality. Aim To assess the degree to which family background variables, parental beliefs and behaviour and child intelligence predict child aggression and adult criminality. Method Data were used from the Colombia County Longitudinal Study, a longitudinal study of 856 children in third grade in New York, in 1959,60. Adult measures of criminal behaviour, child measures taken at age eight, child peer-nominated aggression, child's peer-nominated popularity, child's IQ and parental measures at eight years were used. Results Aggressive children were less intelligent, less popular, rejected more by their parents, had parents who believed in punishment, were less identified with their parents' self-image and were less likely to express guilt. As adults, more aggressive children with parents who were less well educated, experienced more marital disharmony and who seldom attended church were most at risk for arrest. However, after the effect of early aggression was controlled, most effects disappeared and only parents having a strong belief in punishment added significantly to risk of arrest by age 30; the only fact that then reduced the risk of arrest was having parents who attended church often. Both parental authoritarianism and child IQ reduced the risk of conviction for arrested children. Discussion Level of aggression at age eight is the best predictor of criminal events over the next 22 years. A clear implication is that the risk for criminality is affected by much that happens to a boy before he is eight years old. Preventive interventions need to target risk factors that appear to influence the development of early aggression. Copyright © 2002 Whurr Publishers Ltd. [source] Child behaviour and adult personality: comparisons between criminality groups in Finland and SwedenCRIMINAL BEHAVIOUR AND MENTAL HEALTH, Issue 3 2000Professor Lea Pulkkinen Background; Lately there has been an increasing interest in whether personality traits are associated with criminal behaviour in male and female subjects. Criminality and alcohol abuse are often associated. Delinquent adolescents are impulsive and danger seeking. Childhood aggression may be a precursor of adult criminality. Method Using longitudinal data, adult personality and childhood behaviours were examined for groups of non-criminals and criminals of Finnish (n = 268) and Swedish (n + 169) samples, and crime groups were compared in the two cultures. Karolinska Scales of Personality (KSP) were given at adult age and the participants had been observed and rated by their teachers in respect of behaviour in childhood (at age 8 years and 13 years, respectively). Results Male offenders with alcohol problems (Finnish and Swedish) had significantly higher scores on psychopathy-related personality traits in adulthood than other subgroups, as indicated by higher impulsivity, muscular tension and lower socialization. They also displayed higher scores on teacher-rated aggressiveness in childhood than the non-criminal groups. The female subgroup displaying criminal activity was small. It did not differ significantly from non-offenders in adult personality characteristics. Female offenders, however, showed early indications of lower sociability (in Finland) and higher aggressiveness and disharmony in childhood than non-offenders (in Sweden). Discussion The study suggests that early problem behaviours are precursors of subsequent criminal activity in at least two cultures. The results emphasize the importance of longitudinal research programmes. Copyright © 2000 Whurr Publishers Ltd. [source] Retrospective Review of Reconstructive Methods of Conchal Bowl Defects Following Mohs Micrographic SurgeryDERMATOLOGIC SURGERY, Issue 5 2001Nina Wines BSc Background. Mohs micrographic surgery has consistently been demonstrated to be the most effective method for excision of potentially aggressive lesions of the conchal bowl. A variety of techniques are employed to reconstruct the conchal bowl following surgery. Objective. To explore the type and frequency of reconstruction techniques used and the factors influencing the surgeons choice of reconstruction method. Method. Retrospective analysis of 272 patients with conchal bowl tumors. Results. Split thickness skin grafting was the preferred method of reconstruction. The histopathology of the lesions and the size of the post-Mohs defect did not influence the choice of technique, except for lesions less than 1 cm in which healing by secondary intention was favored. Conclusion. Tumor size, type, and aggressiveness did not influence repair technique choice. Surgeon preference was therefore the principle factor dictating method of reconstructive technique following Mohs micrographic surgery. [source] Experimental frost weathering of sandstone by various combinations of saltsEARTH SURFACE PROCESSES AND LANDFORMS, Issue 8 2001R. B. G. Williams Abstract Weathering experiments are reported combining frost and a range of salts that occur naturally on rock faces in western and central Europe. Potassium and ammonium alums enhanced frost weathering quite considerably, both singly and in combination, though they were less potent than halite, the destructiveness of which, at sub-zero temperatures, was again confirmed. By contrast, alunogen and gypsum had little or no effect on rates of frost weathering either singly or in combination. Combining halite and gypsum produced breakdown that was intermediate between that of the two salts individually, as did the combination of gypsum and potassium alum. Breakdown in solutions of ammonium alum and gypsum, and in a combination of potassium and ammonium alum with gypsum, caused greater breakdown over 25 cycles of freeze,thaw than was recorded with the salts singly. The results extend the range of salts known to enhance frost weathering, and show that it is difficult to predict the aggressiveness of combinations of salts by experimenting with each salt separately. Copyright © 2001 John Wiley & Sons, Ltd. [source] Aggression in imported fire ants: an explanation for shifts in their spatial distributions in Southern United States?ECOLOGICAL ENTOMOLOGY, Issue 4 2009HENRY Y. FADAMIRO Abstract 1.,The imported fire ants, Solenopsis invicta Buren (red), S. richteri Forel (black), and their hybrids (S. invicta × S. richteri) are sympatric congeners with overlapping but shifting spatial distributions in northern Alabama and Mississippi, United States. 2.,The abilities of workers of the three ant forms (or species) to recognise non-nestmate conspecifics and heterospecifics were compared in separate aggression bioassays using three group sizes of competitor numbers (battles): 1-1, 5-1, and 5-5 resident,intruder battles. 3.,Workers of all three forms showed significant aggression toward non-nestmate conspecifics and heterospecifics. The results of the intra-specific aggression bioassays showed that S. invicta had the lowest aggression threshold, whereas S. richteri was the least aggressive. Survival rates 1 day after intra-specific encounters were higher for S. richteri than for S. invicta or hybrids, consistent with its lower aggressiveness. 4.,In inter-specific interactions, S. invicta workers showed the greatest aggression and were more aggressive towards S. richteri than to hybrids. Furthermore, survival 1 day after inter-specific encounters was highest for S. invicta workers, whether they were the intruders or residents. The hybrid form was intermediate between both parental forms in aggression and post-aggression survival. 5.,The live 1-1 and 5-5 battles produced similar and consistent results, but differences were amplified in the 5-5 battles, suggesting an effect of group size on aggression. These results may explain the observed shifts in the spatial distributions of the three forms and range restriction of S. richteri in southern United States. [source] The use of field,based social information in eusocial foragers: local enhancement among nestmates and heterospecifics in stingless beesECOLOGICAL ENTOMOLOGY, Issue 3 2003E. Judith Slaa Abstract. 1. Foragers of social insects can be guided to profitable food sources by social information transfer within the nest. This study showed that in addition to such an information-centre strategy, social information in the field also plays an important role in individual foraging decisions. The effect of the presence of a nestmate on individual decision-making on where to forage was investigated in six species of stingless bee that differ in their recruitment system. Some species preferred to feed close to a nestmate (local enhancement) whereas other species actively avoided landing close to a nestmate. The term local inhibition is introduced for this avoidance behaviour. 2. Local enhancement and local inhibition were species specific but were not related to the species' recruitment system. 3. Local enhancement and local inhibition were affected by the individual's experience with the food source. Newly recruited foragers of Trigona amalthea showed local enhancement whereas experienced foragers showed local inhibition. 4. These individual decision-making rules explained accurately the spatial distribution of recruited nestmates: foraging groups of T. amalthea, which shows local inhibition, were more dispersed than foraging groups of Oxytrigona mellicolor, which shows local enhancement. 5. The effect of heterospecifics on stingless bee flower choice was investigated for 18 species combinations. Landing decisions were influenced significantly by the aggressiveness and the body size of the resident bee. Larger and more aggressive heterospecifics were avoided, whereas in some cases less aggressive bees acted as an attraction cue. [source] The role of larval aggression and mobility in the transition between solitary and gregarious development in parasitoid waspsECOLOGY LETTERS, Issue 6 2000G. Boivin Models explaining the appearance of gregariousness in insect parasitoids assume the presence of a tolerance gene that enables nonsiblicidal behaviour in gregarious larvae. Under this assumption, nontolerant individuals should attack and kill tolerant individuals when sharing a host, making this behaviour susceptible to invasion by nontolerant individuals. We propose an alternative hypothesis where gregarious larvae retain their aggressiveness but are less mobile. We tested this hypothesis with two sympatric and congeneric species of Mymaridae, Anaphes victus and Anaphes listronoti, respectively, solitary and gregarious egg parasitoids of a Curculionidae, Listronotus oregonensis. Results obtained in competition experiments and from direct observation of movement in mymariform larvae of both species support the reduced mobility hypothesis. By being immobile while retaining their fighting capacity, A. listronoti mymariform larvae appear to optimize host utilization through gregarious development, but can still defend themselves against sympatric aggressive species. [source] Passage through alternative hosts changes the fitness of Fusarium graminearum and Fusarium pseudograminearumENVIRONMENTAL MICROBIOLOGY, Issue 2 2007Olufemi A. Akinsanmi Summary Species of the necrotrophic fungal pathogen Fusarium that cause head blight and crown rot of cereals including wheat also infect a number of alternative host plants. This raises the prospect of more damaging pathogen strains originating and persisting as highly successful saprophytes on hosts other than wheat. The immediate impact on pathogenic (aggressiveness) and saprophytic (growth rate and fecundity) behaviour of six isolates with low, moderate or high initial aggressiveness was examined in two species of Fusarium after their passage through 10 alternative plant hosts. One passage through alternative hosts significantly reduced the pathogenic fitness of most isolates, but this change was not associated with a concomitant change in their overall saprophytic behaviour. The overall weak association between aggressiveness, fecundity and growth rate both before and after passage through the alternative hosts indicate that pathogenic and saprophytic fitness traits may be independently controlled in both Fusarium species. Thus, there was no trade-off between pathogenic and saprophytic fitness in these necrotrophic plant pathogens. [source] Effects of Social Structure on the Behaviour and Performance of Alternative Reproductive Phenotypes in Male Rock Shrimp, Rhynchocinetes typusETHOLOGY, Issue 4 2008Stefan Dennenmoser Males that adopt alternative mating tactics within a conditional strategy often undergo costly morphological changes when switching to the next phenotype during ontogeny. Whether costs of changing to a subsequent reproductive phenotype are outweighed by a higher mating probability may depend on the frequencies of different phenotypes in a group of competitors. Benefits and costs associated with different phenotype frequencies depend on interactions within and between alternative phenotypes, but the underlying behavioural mechanisms have rarely been studied. Herein, we used the rock shrimp Rhynchocinetes typus as a model: ontogenetic male stages of this species differ in morphological and behavioural traits that indicate alternative reproductive phenotypes. The small, subordinate, male stage (typus) develops via several intermediate stages (intermedius) to the dominant male stage (robustus): in competitive interactions the typus males usually employ the sneaking tactic, while the robustus males invariably employ the monopolizing fighter tactic. In laboratory experiments, we manipulated phenotype frequencies to examine whether there are frequency-dependent effects on searching behaviour, aggressiveness and mating probability. With increasing frequency of robustus males, the rate of aggressive interactions among them increased. Furthermore, robustus males increased walking velocity when more than one robustus male was present. In contrast, typus males did not adjust their searching or aggressive behaviour. The increase of aggressive interactions among robustus males provided more opportunities for typus males to seize a temporarily unguarded female. While typus males exploit fights among robustus males that produce mating opportunities for them, robustus males benefit from typus males, which reveal the presence of receptive females. We suggest that each phenotype benefits from the presence of the other phenotype and suffers costly interference among individuals of the same phenotype. Whether frequency-dependent effects on the mating probability of subordinates also affect their ontogenetic switchpoint should be examined in future studies. [source] Kinship Discrimination and Effects on Social Rank and Aggressiveness Levels in Iberian Red Deer HindsETHOLOGY, Issue 12 2007Francisco Ceacero Kin recognition is a widespread phenomenon that allows individuals to benefit by enhancing their inclusive fitness, and one of its most common forms is reducing aggressiveness towards relatives. We carried out an experiment with Iberian red deer hinds (Cervus elaphus hispanicus) in order to examine kin biases in dominance behaviour and its consequences on social rank. Three enclosed groups (n = 36, 23 and 21, respectively) were monitored during two lactation seasons and social rank hierarchies were assessed by analysing aggressive interactions matrices with Matman 1.1 software. Aggressive interactions between related hinds was significantly smaller than expected (,2 = 5.02, df = 1, p = 0.025), not only between mother and daughter but also in second and third kinship degrees. Although rates of aggressiveness were similar to data published relating free-ranging C. e. scoticus, aggressive interactions with relatives were significantly smaller (,2 = 39.0, df = 1, p < 0.001). This reduction of aggressiveness between related hinds was not the result of these hinds having a lower social rank: social rank was only related to age and weight, but not to kinship degree, calf sex or calving date. The decrease of aggressiveness towards first-, second- and third-degree relatives shows a complex kin recognition system in deer. Possible nepotistic roles in lactation include preventing milk thefts by non-kin and disturbing feeding of unrelated hinds. [source] Does Host Value Influence Female Aggressiveness, Contest Outcome and Fitness Gain in Parasitoids?ETHOLOGY, Issue 4 2007Marlene Goubault Intraspecific competition for resources is common in animals and may lead to physical contests. Contest outcomes and aggressiveness can be influenced by the resource holding potential of contestants but also by their perception of the resource value (RV). Competitors may assess resource quality directly (real RV) but may also estimate it according to their physiological status and their experience of the habitat quality (subjective RV). In this article, we studied contests between females of the solitary parasitoid Pachycrepoideus vindemmiae Rondani (Hymenoptera: Pteromalidae) when exploiting simultaneously a host, a Delia radicum L. (Diptera: Anthomyiidae) pupa. We tested the effect of factors modifying host value on the occurrence of agonistic behaviours, contest outcomes and host exploitation. The factors tested were: the quality of the previous habitat experienced by females, female egg load, host parasitism status and the stage reached by the owner female in her behavioural oviposition sequence. Females successfully protected their host against intruders during its exploitation, but not after oviposition, and their aggressiveness did not seem to be influenced by their perception of the RV. The fact that the host is subsequently parasitized by the opponent females appears to mainly depend on the host selectiveness of females. [source] Multiple Cues in Status Signalling: The Role of Wingbars in Aggressive Interactions of Male House SparrowsETHOLOGY, Issue 10 2006Veronika Bókony During aggressive interactions, animals may signal their competitive ability by various ornaments referred to as badges of status. The use of a single badge predicting dominance rank occurs in many vertebrate species. However, animals often display multiple ornaments that may convey information about either different or the same aspects of the signaller's quality, or alternatively, may serve as signal amplifiers. We observed the fighting behaviour of male house sparrows in two captive flocks to investigate whether they may use multiple cues in status signalling during aggressive interactions. Beside the status-signalling bib, male sparrows possess a conspicuous white wingbar that they often display upon aggressive encounters. We tested whether bib size and the wingbar's conspicuousness (i.e. its achromatic contrast with the neighbouring dark feathers) or its area predicted success in various aspects of fighting. We found that bib size strongly predicted overall fighting success (i.e. proportion of fights won) and defence success (i.e. proportion of successful defences out of all attacks received). Wingbar conspicuousness was positively related to defence success after controlling for the effect of bib size in multivariate analyses. Furthermore, displaying the wings also tended to improve the birds' success in defence but not in attack. Wingbar area was unrelated to any measured aspect of fighting ability. We suggest that bib size and wingbar conspicuousness may convey multiple messages on fighting abilities, specifically on overall aggressiveness and defending potential, respectively. Alternatively, wingbars may serve as amplifiers for the wing displays of aggressive motivation. Thus, male sparrows may use multiple cues in assessing the competitive ability of opponents during social interactions. [source] Strophe Length in Spontaneous Songs Predicts Male Response to Playback in the Hoopoe Upupa epopsETHOLOGY, Issue 5 2004Manuel Martín-Vivaldi Hoopoe (Upupa epops, Coraciformes) males produce a very simple song during the breeding season in order to attract females and repel intruders. Strophes vary in length (i.e. number of elements) both within and between males, and previous studies have shown that this song cue is positively correlated with male condition and breeding success. In the present study we tested whether strophe length of males influences male behaviour during intra-sexual contests, in a colour-ringed population in southeast Spain. Paired males were presented with a recorded song with long strophes during the pre-laying period, while they were near their mates, in order to provoke male mate-defence behaviour. Most males responded to the playback, but the strategy of defence adopted depended on their own strophe length in spontaneous songs recorded before the experiments. While singing responses were common to most of the males, only those using long strophes adopted the most risky strategy of approaching the loudspeaker. However, the males that approached produced abnormal songs during playback, that were shorter and with fewer strophes than those of males that did not approach, and used shorter strophes in comparison with spontaneous songs before the experiment. These differences in quality of the song produced in response to the playback suggest that long-strophe males were basing their response mainly on attacking rather than singing, while short-strophe males tried to resolve the contest at a distance by means of their song. These results show that strophe length reflects some component of the competitive ability of males (either physical strength or aggressiveness) in the hoopoe, which together with previous results regarding its role for female choice, show that it is a sexual signal with dual function. [source] A case of small-cell gastric carcinoma with an adenocarcinoma component and hepatic metastases: treatment with systemic and intra-hepatic chemotherapyEUROPEAN JOURNAL OF CANCER CARE, Issue 5 2007T. CIOPPA md Primary small-cell carcinoma (SmCC) of the stomach is a rare neoplasm with a poor prognosis and unclear histogenesis: to date, only 50 cases, including ours, have been reported in the literature. In the World Health Organization gastrointestinal tumours' classification, SmCC of the stomach has been recognized as an ,independent entity affecting the stomach'. In this paper, the authors present a clinical case and the surgical treatment of an adult with a SmCC of the stomach associated with gastric adenocarcinoma. After laparotomy, a large neoplasm with locoregional extension and multiple liver metastases were found. A palliative resection, subtotal gastrectomy, was performed, followed by systemic and intra-hepatic chemotherapy: computed tomography scan demonstrated a marked response, but the patient died 15 months after the operation. A review of the literature showed that the diagnosis of gastric SmCC is based on immunohistochemical findings. Our experience confirmed the high aggressiveness of this neoplasm, which is generally diagnosed in advanced stage and is unresponsive to chemotherapy, but the combined use of systemic and intra-hepatic chemotherapy shows an acceptable result in a palliative care perspective. [source] Inactivation of the gene for the nuclear receptor tailless in the brain preserving its function in the eyeEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 8 2007Thorsten Belz Abstract During embryogenesis, tailless, an orphan member of the nuclear receptor family, is expressed in the germinal zones of the brain and the developing retina, and is involved in regulating the cell cycle of progenitor cells. Consequently, a deletion of the tailless gene leads to decreased cell number with associated anatomical defects in the limbic system, the cortex and the eye. These structural abnormalities are associated with blindness, increased aggressiveness, poor performance in learning paradigms and reduced anxiousness. In order to assess the contribution of blindness to the behavioural changes, we established tailless mutant mice with intact visual abilities. We generated a mouse line in which the second exon of the tailless gene is flanked by loxP sites and crossed these animals with a transgenic line expressing the Cre recombinase in the neurogenic area of the developing brain, but not in the eye. The resulting animals have anatomically indistinguishable brains compared with tailless germline mutants, but are not blind. They are less anxious and much more aggressive than controls, like tailless germline mutants. In contrast to germline mutants, the conditional mutants are not impaired in fear conditioning. Furthermore, they show good performance in the Morris water-maze despite severely reduced hippocampal structures. Thus, the pathological aggressiveness and reduced anxiety found in tailless germline mutants are due to malformations caused by inactivation of the tailless gene in the brain, but the poor performance of tailless null mice in learning and memory paradigms is dependent on the associated blindness. [source] | |||||||||||||||||||||||||||||||||||||||||||