Home About us Contact
|
Home About us Contact | ||
|
|
||
Disturbed
Terms modified by Disturbed Selected AbstractsPredicting long-term sickness absence from sleep and fatigueJOURNAL OF SLEEP RESEARCH, Issue 4 2007TORBJORN AKERSTEDT Summary Disturbed or shortened sleep is prospectively related to disease. One might also expect that sickness absence would be another consequence but very little data seem to exist. The present study used 8300 individuals in a national sample to obtain information on reports of disturbed sleep and fatigue 1 year and merged this with data on long-term sickness absence 2 years later. A logistic regression analysis was applied to the data with adjustments for demographic and work environment variables. The results showed that individuals without registered sickness absence at the start had a higher probability of entering a period of long-term (,90 days, odds ratio [OR] = 1.24 with 95% confidence interval [CI] = 1.02,1.51) sickness absence 2 years later if they reported disturbed sleep at the start. The figure for fatigue was OR = 1.35 (CI = 1.14,1.60). When fatigue or disturbed sleep was separately excluded the OR increased to OR = 1.44 and OR = 1.47, respectively. Intermediate sickness absence (14,89 days) showed similar but slightly weaker results. The results indicate that disturbed sleep and fatigue are predictors of long-term absence and it is suggested that impaired sleep may be part of a chain of causation, considering its effects on fatigue. [source] Mechanisms blocking Pinus sylvestris colonization of Mediterranean mountain meadowsJOURNAL OF VEGETATION SCIENCE, Issue 5 2002Jorge Castro Tutin et al. (1964,1980) Abstract. In southern Mediterranean Pinus sylvestris forests there are grassy meadows that resist invasion of trees despite the proximity to seed sources. In this study, we investigate the mechanisms blocking colonization by Pinus sylvestris of the meadows. Two experiments were conducted in which seeds were sown either at 1 cm depth or on the surface to simulate dispersal, and three treatments of vegetation removal were applied: Disturbed (where the herbaceous layer was eliminated, exposing the mineral soil), Clipped (vegetation cut at ground level) and Control (no disturbance of the herbaceous layer). In addition, the effect of seed predators was controlled by using wire cages in the case of the surface sown experiment. When seeds were sown at 1 cm depth, seedling emergence was not reduced by the herbaceous layer. In contrast, when seeds were surface sown and predators were excluded, the rate of emergence was low in the Control treatment, intermediate in Clipped and high in Disturbed. Seedling emergence was, however, minimal when predators were not excluded, irrespective of the disturbance level. Seedling survival and growth after three years of study were similar among treatments. The results show that the seed predation and the physical barrier created by the herbaceous layer are the two mechanisms blocking the encroachment of Pinus sylvestris onto these Mediterranean mountain meadows, limiting the regeneration and potential expansion of the forest. [source] Testing the Home-Site Advantage in Forest Trees on Disturbed and Undisturbed SitesRESTORATION ECOLOGY, Issue 3 2010Eleanor K. O'Brien Restoration of plant populations is often undertaken using seed or plants from local sources because it is assumed they will be best adapted to the prevailing conditions. However, the effect of site disturbance on local adaptation has rarely been examined. We assessed local adaptation in three southwestern Australian forest tree species (Eucalyptus marginata, Corymbia calophylla, and Allocasuarina fraseriana) using reciprocal transplant trials at disturbed and undisturbed sites. Performance of plants within the trials was assessed over 2 years. Planting location accounted for the majority of the variation in most measures of performance, although significant variation of percent emergence among source populations was also detected. In all species, percent emergence and survival of plants sourced from Darling Range populations was significantly higher than that of plants from the Swan Coastal Plain, regions of contrasting edaphic and climatic environment. Survival of E. marginata over the first 18 months and emergence of C. calophylla were both higher in local plants, providing at least weak evidence for local adaptation. Where a local advantage was observed, the relative performance of local and nonlocal seed did not vary among disturbed and undisturbed sites. Evidence for enhanced establishment from local seed in at least one species leads us to recommend that where sufficient high-quality seed supplies exist locally, these should be used in restoration. We also recommend longer-term studies to include the possibility of local adaptation becoming evident at later life history stages. [source] Interaction of exchange and differential relaxation in the saturation recovery behavior of the binary spin-bath model for magnetization transferCONCEPTS IN MAGNETIC RESONANCE, Issue 4 2006Gunther Helms Abstract Most closed-form analytical solutions of the binary spin-bath are difficult to interpret in terms of underlying physics. The key notions are the presence of a kinetic and a thermal equilibrium and that the time course of saturation recovery under conditions of fast exchange can be understood as conjoint relaxation and lossless transfer. By introducing a suitable parameter, it is shown how exchange and differential relaxation counteract each other: the amount of transferred saturation (transfer term) is altered and the kinetic equilibrium appears slightly disturbed (difference term). Although the factorization formally represents the general solution of saturation recovery in the binary spin-bath, this interpretation applies only to the case of fast exchange and slow relaxation. By calculating the set of parameters for a wide range of hypothetical relaxation rates, it was shown that the difference term is crucial to describe the transition to the slow-exchange limit. The transfer term vanishes as the two pools appear decoupled in this approximation. © 2006 Wiley Periodicals, Inc. Concepts Magn Reson Part A 28A: 291,298, 2006. [source] Effects of Conversion of Dry Tropical Forest to Agricultural Mosaic on Herpetofaunal AssemblagesCONSERVATION BIOLOGY, Issue 2 2008IRERI SUAZO-ORTUÑO atributos de vulnerabilidad; bosque tropical seco; ensambles herpetofaunísticos; modificación del hábitat; mosaico agrícola Abstract:,We explored the impact of forest conversion to agricultural mosaic on anuran, lizard, snake, and turtle assemblages of Neotropical dry forests. Over 2 years, we sampled 6 small watersheds on the west coast of Mexico, 3 conserved and 3 disturbed. The disturbed watersheds were characterized by a mosaic of pastures and cultivated fields (corn, beans, squash) intermingled with patches of different successional stages of dry forest. In each watershed, we conducted 11 diurnal and nocturnal time-constrained searches in 10 randomly established plots. We considered vulnerability traits of species in relation to habitat modification. Eighteen anuran, 18 lizard, 23 snake, and 3 turtle species were recorded. Thirty-six species (58%) occurred in both forest conditions, and 14 (22%) and 12 species (19%) occurred only in the conserved and disturbed sites, respectively. Assemblages responded differently to disturbance. Species richness, diversity, and abundance of lizards were higher in disturbed forests. Anuran diversity and species richness were lower in disturbed forest but abundance was similar in both forest conditions. Diversity, richness, and abundance of turtles were lower in disturbed forest. The structure and composition of snake assemblages did not differ between forest conditions. We considered species disturbance sensitive if their abundance was significantly less in disturbed areas. Four anuran (22%), 2 lizard (11%), and 3 turtle (100%) species were sensitive to disturbance. No snake species was sensitive. The decline in abundance of disturbance-sensitive species was associated with the reduction of forest canopy cover, woody stem cover, roots, and litter-layer ground cover. Anuran species with small body size and direct embryonic development were especially sensitive to forest disturbance. An important goal for the conservation of herpetofauna should be the determination of species traits associated with extinction or persistence in agricultural mosaics. Resumen:,Exploramos el impacto de la conversión de bosques a mosaico agrícola sobre ensambles de lagartijas, serpientes y tortugas de bosques Neotropicales secos. Durante 2 años muestreamos 6 cuencas pequeñas, 3 conservadas y 3 perturbadas, en la costa occidental de México. Las cuencas perturbadas se caracterizaron por un mosaico de pastizales y campos cultivados (maíz, frijol, calabaza) entremezclados con parches de bosque seco en diferentes etapas sucesionales. En cada cuenca, realizamos 11 búsquedas diurnas y nocturnas en 10 parcelas establecidas aleatoriamente. Consideramos los atributos de vulnerabilidad de especies en relación con la modificación del hábitat. Registramos 18 especies de lagartijas, 23 de serpientes y 3 de tortugas. Treinta y seis especies (58%) ocurrieron en ambas condiciones de bosque, y 14 (22%) y 12 (19%) especies solo ocurrieron en los sitios conservados y perturbados, respectivamente. Los ensambles respondieron a la perturbación de manera diferente. La riqueza de especies, la diversidad y la abundancia de lagartijas fueron mayores en los bosques perturbados. La diversidad y riqueza de especies de anuros fueron menores en el bosque perturbado pero la abundancia fue similar en ambas condiciones de bosque. La diversidad, riqueza de especies y abundancia de tortugas fueron menores en el bosque perturbado. La estructura y la composición de los ensambles de serpientes no difirieron entre condiciones de bosque. Consideramos que las especies eran sensibles a la perturbación si su abundancia fue significativamente menor en las áreas perturbadas. Cuatro (22%) especies de anuros, 2 (11%) de lagartijas y 3 (100%) de tortugas fueron sensibles a la perturbación. Ninguna especie de serpiente fue sensible. La declinación en la abundancia de especies sensibles a la perturbación se asoció con la reducción en la cobertura del dosel, de tallos leñosos, raíces y hojarasca. Las especies de anuros de cuerpo pequeño y desarrollo embrionario directo fueron especialmente sensibles a la perturbación del bosque. La determinación de atributos de las especies asociadas con su extinción o persistencia en mosaicos agrícolas debería ser una meta importante para la conservación de la herpetofauna. [source] Effects of Forest Management on Amphibians and Reptiles in Missouri Ozark ForestsCONSERVATION BIOLOGY, Issue 1 2004ROCHELLE B. RENKEN Within even-aged management sites, we also focused on the local-scale effects of clearcutting on these species by comparing relative abundance among plots located within clearcut stands, 50 m away from clearcut stands, and 200 m away from clearcut stands. Pretreatment sampling of species abundance occurred from 1992 through 1995, and post-treatment sampling occurred from 1997 through 2000. At the landscape scale, treatment significantly affected the abundance of Bufo americanus. This species declined less on even-aged management sites than on control sites, but the general decline on all sites suggests that other factors may have contributed to this result. Within even-aged management sites, most amphibian species declined and some reptile species increased relative to pretreatment abundances within clearcut stands. We found significant effects of distance from clearcut for two amphibian species, Ambystoma maculatum and Rana clamitans, and two reptile species, Scincella lateralis and Sceloporus undulatus. In general, we conclude that clearcuts within even-aged management sites locally affected amphibian and reptile species but, at a larger spatial scale, we did not detect significant effects of even-aged and uneven-aged forest management. These findings represent relatively short-term data but suggest that forest management and maintenance of biodiversity may be compatible when relatively small amounts of the landscape are disturbed. Resumen:,Como parte del Proyecto Ecosistema del Bosque Ozark de Missouri (PEBOM), evaluamos experimentalmente los impactos de la gestión de bosques sobre la abundancia relativa de anfibios y reptiles en los bosques Ozark, Missouri (E.U.A.). Utilizando sitios de estudio extensos (es decir, de tamaño promedio de 400ha) como la unidad experimental, estudiamos los efectos de tratamientos de manejo de bosques de edad uniforme y dispar comparados con el manejo sin cosecha (es decir, control) sobre la abundancia relativa de 13 especies focales de anfibios y reptiles. En los sitios de manejo de edad uniforme, también analizamos los efectos a escala local de la tala completa sobre estas especies comparando la abundancia relativa entre parcelas localizadas dentro de los claros talados, a 50 m y 200 m de los claros. Para determinar la abundancia de especies, se tomaron muestras previas al tratamiento de 1992 a 1995, y muestras posteriores al tratamiento de 1997 a 2000. A la escala de paisaje, el tratamiento afectó significativamente la abundancia de Bufo americanus. La abundancia de esta especie disminuyó menos en sitios de manejo de edad uniforme que en los sitios control, pero la disminución general en todos los sitios sugiere que otros factores pudieron haber contribuido a este resultado. En los sitios de manejo de edad uniforme, la abundancia de la mayoría de las especies de anfibios disminuyó y algunas especies de reptiles incrementaron en relación con las abundancias previas al tratamiento dentro de los claros talados. Encontramos efectos significativos de la distancia del claro para dos especies de anfibios, Ambystoma maculatum y Rana clamitans, y dos especies de reptiles, Scincella lateralis y Sceloporus undulatus. En general, concluimos que la tala en sitios de edad uniforme afectó localmente a las especies de anfibios y reptiles, pero a una mayor escala espacial, no detectamos impactos significativos entre el manejo de sitios de edad uniforme y dispar. Estos hallazgos representan datos de relativamente corto plazo pero sugieren que la gestión de bosques y el mantenimiento de la biodiversidad pueden ser compatibles cuando se perturban superficies relativamente pequeñas del paisaje. [source] The involvement of phospholipases C and D in the asymmetric division of subsidiary cell mother cells of Zea maysCYTOSKELETON, Issue 11 2008Panagiotis Apostolakos Abstract In the present study, the involvement of phospholipase C and D (PLC and PLD) pathways in the asymmetric divisions that produce the stomatal complexes of Zea mays was investigated. In particular, the polar organization of microtubules (MTs) and actin filaments (AFs) and the process of asymmetric division were studied in subsidiary cell mother cells (SMCs) treated with PLC and PLD modulators. In SMCs treated with butanol-1 (but-1), which blocks phosphatidic acid (PA) production via PLDs, AF-patch formation laterally to the inducing guard cell mother cell (GMC) and the subsequent asymmetric division were inhibited. In these SMCs, cell division plane determination, as expressed by MT preprophase band (MT-PPB) formation, was not disturbed. Exogenously applied PA partially relieved the but-1 effects on SMCs. In contrast to SMCs, but-1 did not affect the symmetric GMC division. Inhibition of the PLC catalytic activity by neomycin or U73122 resulted in inhibition of asymmetric SMC division, while AF-patch and MT-PPB were organized as in control SMCs. These data show that the PLC and PLD signaling pathways are involved in the transduction and/or perception of the inductive stimulus that is emitted by the GMCs and induces the polar AF organization and asymmetric SMC division. In contrast, division plane determination in SMCs, as expressed by MT-PPB formation, does not depend on PLC and PLD signaling pathways. Cell Motil. Cytoskeleton 2008. © 2008 Wiley-Liss, Inc. [source] Pigment cell distributions in different tissues of the zebrafish, with special reference to the striped pigment patternDEVELOPMENTAL DYNAMICS, Issue 2 2005Masashi Hirata Abstract The orderly pigment pattern of zebrafish (Danio rerio) is a good model system for studying how spatial patterns form in animals. Recent molecular genetic studies have shown that interactions between the pigment cells play major roles in pattern formation. In the present study, we performed comparative transmission electron microscopy of pigment cells, in order to clarify the structural interactions of pigment cells in tissues with and without a striped pattern. In patterned tissues, pigment cells were distributed as a one-cell-thick sheet. The layer order of the sheets is always kept strictly. In tissues without a striped pattern, the layer order was often disturbed or the cells were distributed in a scattered, double-sheeted, or an accumulated pile. Our observations suggest that the underlying mechanism that controls the vertical order of the pigment cells is related to that controlling the stripe pattern. Developmental Dynamics 234:293,300, 2005. © 2005 Wiley-Liss, Inc. [source] Dorsal versus ventral scales and the dorsoventral patterning of chick foot epidermisDEVELOPMENTAL DYNAMICS, Issue 3 2004Fabrice Prin Abstract The dorsal and ventral scales of the chick foot can be distinguished morphologically and molecularly: the dorsal oblong overlapping scuta expressing both , and , keratins, and the ventral roundish nonprotruding reticula expressing only , keratins. The question arises how En-1 and Lmx1, whose role in dorsoventral limb patterning has been well established, can affect skin morphogenesis, which occurs 8 to 12 days later. Forced expression of En-1 or of Lmx1 in the hindlimb have, respectively, as expected, a ventralizing or a dorsalizing effect on skin, leading to the formation of either reticula-type or scuta-type scales on both faces. In both cases, however, the scales are abnormal and even glabrous skin without any scales at all may form. The normal inductive interactions between dermis and epidermis are disturbed after En-1 or Lmx1 misexpression. Effectively, while Lmx1 endows the dermal precursors of the ventral region with scuta inducing ability, En-1 blocks the competence of the dorsal epidermis to build scuta. Developmental Dynamics 229:564,578, 2004. © 2004 Wiley-Liss, Inc. [source] Visuospatial attention disturbance in Duchenne muscular dystrophyDEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 2 2010MARIA CLARA DRUMMOND SOARES DE MOURA Aim, The cognitive deficits present in the Duchenne muscular dystrophy (DMD) are not yet well characterized. Attention, considered to be the brain mechanism responsible for the selection of sensory stimuli, could be disturbed in DMD, contributing, at least partially, to the observed global cognitive deficit. The aim of this study was to investigate attentional function in individuals with DMD. Method, Twenty-five males (mean age 12y; SD 2y 2mo) with DMD and 25 healthy males (mean age 12y; SD 2y) were tested in a visuospatial task (Posner computerized test). They were instructed to respond as quickly as possible to a lateralized visual target stimulus with the ipsilateral hand. Their attention was automatically orientated by a peripheral prime stimulus or, alternatively, voluntarily orientated by a central spatially informative cue. Results, The main result obtained was that the attentional effect (sum of the benefit and the cost of attention) did not differ between the two groups in the case of automatic attention (p=0.846) but was much larger for individuals with DMD than for comparison individuals in the case of voluntary attention (p<0.001). Interpretation, The large voluntary attentional effect exhibited by the participants with DMD seems similar to that of younger children, suggesting that the disease is associated with delayed maturation of voluntary attention mechanisms. [source] Serotonin and dopamine transporter binding in children with autism determined by SPECTDEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 8 2008Ismo Makkonen MD Disturbances in the serotonergic system have been recognized in autism. To investigate the association between serotonin and dopamine transporters and autism, we studied 15 children (14 males, one female; mean age 8y 8mo [SD 3y 10mo]) with autism and 10 non-autistic comparison children (five males, five females; mean age 9y 10mo [SD 2y 8mo]) using single-photon emission computed tomography (SPECT) with [123I] nor-,-CIT. The children, with autism were studied during light sedation. They showed reduced serotonin transporter (SERT) binding capacity in the medial frontal cortex, midbrain, and temporal lobe areas. However, after correction due to the estimated effect of sedation, the difference remained significant only in the medial frontal cortex area (p=0.002). In the individuals with autism dopamine transporter (DAT) binding did not differ from that of the comparison group. The results indicate that SERT binding capacity is disturbed in autism. The reduction is more evident in adolescence than in earlier childhood. The low SERT binding reported here and the low serotonin synthesis capacity shown elsewhere may indicate maturation of a lesser number of serotonergic nerve terminals in individuals with autism. [source] Context-Oriented Model Development in Psychotherapy Planning (,COMEPP'): a useful adjunct to diagnosis and therapy of severe personality disordersACTA PSYCHIATRICA SCANDINAVICA, Issue 3 2004M. Fischer-Kern Objective:, Pathogenous interpersonal (e.g. interfamilial) relationships and reference styles can compromise treatment efforts in severely disturbed (i.e. psychotic or borderline) patients. The integration of family- and individual-centred starting points may be useful in establishing interdisciplinary treatment concepts in these patients. Context-Oriented Model Development in Psychotherapy Planning (COMEPP) represents a diagnostic and therapy planning process, integrating both systemic and psychoanalytic conceptualizations. Method:, COMEPP is exemplified by the case of a young man with psychotic personality disorder who had previously been unresponsive to pharmacological and psychological treatment. Results:, After psycho-dynamical conflicts (i.e. primitive projective processes from the patient's mother to her son) had been elucidated during the COMEPP process, a sufficient treatment setting could be established. Conclusion:, COMEPP provides a psychotherapeutical approach to treatment planning on case-specific premises and may serve as an adjunct to concomitant pharmacological and psychological treatment strategies in so-called ,therapy refractory' patients. [source] The mechanisms that underlie glucose sensing during hypoglycaemia in diabetesDIABETIC MEDICINE, Issue 5 2008R. McCrimmon Abstract Hypoglycaemia is a frequent and greatly feared side-effect of insulin therapy, and a major obstacle to achieving near-normal glucose control. This review will focus on the more recent developments in our understanding of the mechanisms that underlie the sensing of hypoglycaemia in both non-diabetic and diabetic individuals, and how this mechanism becomes impaired over time. The research focus of my own laboratory and many others is directed by three principal questions. Where does the body sense a falling glucose? How does the body detect a falling glucose? And why does this mechanism fail in Type 1 diabetes? Hypoglycaemia is sensed by specialized neurons found in the brain and periphery, and of these the ventromedial hypothalamus appears to play a major role. Neurons that react to fluctuations in glucose use mechanisms very similar to those that operate in pancreatic B- and A-cells, in particular in their use of glucokinase and the KATP channel as key steps through which the metabolic signal is translated into altered neuronal firing rates. During hypoglycaemia, glucose-inhibited (GI) neurons may be regulated by the activity of AMP-activated protein kinase. This sensing mechanism is disturbed by recurrent hypoglycaemia, such that counter-regulatory defence responses are triggered at a lower glucose level. Why this should occur is not yet known, but it may involve increased metabolism or fuel delivery to glucose-sensing neurons or alterations in the mechanisms that regulate the stress response. [source] Repaglinide treatment amplifies first-phase insulin secretion and high-frequency pulsatile insulin release in Type 2 diabetesDIABETIC MEDICINE, Issue 10 2005M. Hollingdal Abstract Aims/hypothesis First-phase insulin release and coordinated insulin pulsatility are disturbed in Type 2 diabetes. The present study was undertaken to explore a possible influence of the oral prandial glucose regulator, repaglinide, on first-phase insulin secretion and high-frequency insulin pulsatility in Type 2 diabetes. Methods We examined 10 patients with Type 2 diabetes in a double-blind placebo-controlled, cross-over design. The participants were treated for 6 weeks with either repaglinide [2,9 mg/day (average 5.9 mg)] or placebo in random order. At the end of each treatment period, first-phase insulin secretion was measured. Entrainment of insulin secretion was assessed utilizing 1-min glucose bolus exposure (6 mg/kg body weight every 10 min) for 60 min during (A) baseline conditions, i.e. 12 h after the last repaglinide/placebo administration, and (B) 30 min after an oral dose of 0.5 mg repaglinide/placebo with subsequent application of time-series analyses. Results Postprandial (2-h) blood glucose was significantly reduced by repaglinide after 5 weeks of treatment (P < 0.001). The fall in HbA1c did not reach statistical significance (P = 0.07). AUCins,0,12 min during the first-phase insulin secretion test was enhanced (P < 0.05). In addition, glucose entrained insulin secretory burst mass and amplitude increased markedly (burst mass: repaglinide, 44.4 ± 6.0 pmol/l/pulse vs. placebo, 31.4 ± 3.3 pmol/l/pulse, P < 0.05; burst amplitude: repaglinide, 17.7 ± 2.4 pmol/l/min vs. placebo, 12.6 ± 1.3 pmol/l/min, P < 0.05) while basal insulin (non-pulsatile) secretion was unaltered. After acute repaglinide exposure (0.5 mg) basal insulin secretion increased significantly (P < 0.05). Neither acute nor chronic repaglinide administration influenced frequency or regularity of insulin pulses during entrainment. Conclusion/interpretation Repaglinide augments first-phase insulin secretion as well as high-frequency insulin secretory burst mass and amplitude during glucose entrainment in patients with Type 2 diabetes, while regularity of the insulin release process was unaltered. Diabet. Med. (2005) [source] Effects of physical disturbance and granivory on establishment of native and alien riparian trees in Colorado, U.S.A.DIVERSITY AND DISTRIBUTIONS, Issue 1-2 2001Gabrielle L. Katz In western North America, the alien Elaeagnus angustifolia L. invades riparian habitats usually dominated by pioneer woody species such as Populus deltoides Marshall ssp. monilifera (Aiton) Eckenwalder. We conducted manipulative field experiments to compare the importance of physical disturbance and granivory for seedling establishment of these two species. We planted seeds of both species in disturbed and undisturbed study plots, and used exclosures, seed dish trials and live-trapping to assess the role of granivory. Seedling establishment of both species was increased by physical disturbance and seeds of both species were subject to granivory. However, the relative importance of these two factors differed between species. For P. deltoides, lack of physical disturbance prevented seedling establishment in uncleared subplots, but granivory did not prevent seedling establishment outside of exclosures. For E. angustifolia, granivory prevented seedling establishment outside of exclosures, but lack of physical disturbance did not prevent establishment in uncleared subplots. The lesser dependence on disturbance may enable E. angustifolia to invade areas characterized by low levels of fluvial disturbance, such as floodplains along regulated rivers, where P. deltoides recruitment does not occur. Populations of granivorous rodents may affect the susceptibility of riparian ecosystems to invasion by E. angustifolia. [source] Naturalization and invasion of alien plants: concepts and definitionsDIVERSITY AND DISTRIBUTIONS, Issue 2 2000David M. Richardson Abstract., Much confusion exists in the English-language literature on plant invasions concerning the terms ,naturalized' and ,invasive' and their associated concepts. Several authors have used these terms in proposing schemes for conceptualizing the sequence of events from introduction to invasion, but often imprecisely, erroneously or in contradictory ways. This greatly complicates the formulation of robust generalizations in invasion ecology. Based on an extensive and critical survey of the literature we defined a minimum set of key terms related to a graphic scheme which conceptualizes the naturalization/invasion process. Introduction means that the plant (or its propagule) has been transported by humans across a major geographical barrier. Naturalization starts when abiotic and biotic barriers to survival are surmounted and when various barriers to regular reproduction are overcome. Invasion further requires that introduced plants produce reproductive offspring in areas distant from sites of introduction (approximate scales: > 100 m over < 50 years for taxa spreading by seeds and other propagules; > 6 m/3 years for taxa spreading by roots, rhizomes, stolons or creeping stems). Taxa that can cope with the abiotic environment and biota in the general area may invade disturbed, seminatural communities. Invasion of successionally mature, undisturbed communities usually requires that the alien taxon overcomes a different category of barriers. We propose that the term ,invasive' should be used without any inference to environmental or economic impact. Terms like ,pests' and ,weeds' are suitable labels for the 50,80% of invaders that have harmful effects. About 10% of invasive plants that change the character, condition, form, or nature of ecosystems over substantial areas may be termed ,transformers'. [source] Neuroprotection in emerging psychotic disordersEARLY INTERVENTION IN PSYCHIATRY, Issue 2 2007Gregor Berger Abstract Aim:, The emerging phase of psychotic disorders is pleomorphic and fluctuates in presentation. Hence, from a clinical perspective, treatment modalities are often unclear. This paper investigates the rational and potential use of neuroprotective agents in emerging psychotic disorders. Methods:, Medline databases were searched from 1966 to 2006 followed by the cross-checking of references using following keywords: neuroprotection, apoptosis, natural cell death, neurodevelopment, plasticity, neurogenesis, combined with brain and schizophrenia. Results:, Agents such as atypical antipsychotics, antidepressants, omega-3 fatty acids, modulators of glutamateric neurotransmission (e.g. ampakines, glycine, memantine), erythropoietin, N -acetylcysteine, COX-2 inhibitors or antioxidants have neuroprotective (anti-apoptotic) properties and may therefore be able to protect brain maturational processes disturbed in emerging psychotic disorders. Clinical trials suggest that atypical antipsychotics, antidepressants, omega-3 fatty acids and low-dose lithium as sole treatments were able to improve symptoms and functioning, and delay or in some cases even prevent the onset of frank psychosis. Initially these substances have been chosen because they have been used either as sole or augmentation treatments in established psychotic disorders. However, chronicity and already effective treatments may overshadow their potential clinical use in emerging (prodromal) psychosis. Conclusion:, Neuroprotection as a new treatment paradigm for at-risk mental states seems to be promising and pilot data are suggestive that more benign interventions may already be sufficient to delay or even prevent the onset of frank psychosis. A coordinated research effort will be necessary to address the question which agents should be used under which circumstances. [source] Topographic controls upon soil macropore flowEARTH SURFACE PROCESSES AND LANDFORMS, Issue 3 2009Joseph Holden Abstract Macropores are important components of soil hydrology. The spatial distribution of macropore flow as a proportion of saturated hydraulic conductivity was tested on six humid,temperate slopes using transects of tension infiltrometer measurements. Automated water table and overland flow monitoring allowed the timing of, and differentiation between, saturation-excess overland flow and infiltration-excess overland flow occurrence on the slopes to be determined and related to tension-infiltrometer measurements. Two slopes were covered with blanket peat, two with stagnohumic gleys and two with brown earth soils. None of the slopes had been disturbed by agricultural activity within the last 20 years. This controlled the potential for tillage impacts on macropores. The proportion of near-surface macropore flow to saturated hydraulic conductivity was found to vary according to slope position. The spatial patterns were not the same for all hillslopes. On the four non-peat slopes there was a relationship between locations of overland flow occurrence and reduced macroporosity. This relationship did not exist for the peat slopes investigated because they experienced overland flow across their whole slope surfaces. Nevertheless, they still had a distinctive spatial pattern of macropore flow according to slope position. For the other soils tested, parts of slopes that were susceptible to saturation-excess overland flow (e.g. hilltoes or flat hilltops) tended to have least macropore flow. To a lesser extent, for the parts of slopes susceptible to infiltration-excess overland flow, the proportion of macropore flow as a component of infiltration was also smaller compared with the rest of the slope. The roles of macropore creation and macropore infilling by sheet wash are discussed, and it is noted that the combination of these may result in distinctive topographically controlled spatial patterns of macropore flow. Copyright © 2008 John Wiley & Sons, Ltd. [source] What shapes Eurasian lynx distribution in human dominated landscapes: selecting prey or avoiding people?ECOGRAPHY, Issue 4 2009Mathieu Basille In the multi-use landscape of southern Norway, the distribution of lynx is likely to be determined both by the abundance of their favoured prey , the roe deer , and the risk associated with the presence of humans because most lynx mortalities are caused by humans (recreational harvest, poaching, vehicle collisions). We described the distribution of the reproductive portion of the lynx population based on snow-track observations of females with dependent kittens collected over 10,yr (1997,2006) in southern Norway. We used the ecological-niche factor analysis to examine how lynx distribution was influenced by roe deer, human activity, habitat type, environmental productivity and elevation. Our first prediction that lynx should be found in areas of relatively high roe deer abundance was supported. However, our second prediction that lynx should avoid human activity was rejected, and lynx instead occupied areas more disturbed in average than those available (with the exception of the most densely occupied areas). Lynx, however, avoided the most disturbed areas and our third prediction of a trade-off between abundance of prey and avoidance of human activity was supported. On the one hand, roe deer in the most disturbed areas benefit to a large extent from current human land use practices, potentially allowing them to escape predation from lynx. On the other hand, the situation is not so favourable for the predators who are restricted in competition refuges with medium to low prey densities. The consequence is that lynx conservation will have to be achieved in a human modifed environment where the potential for a range of conflicts and high human-caused mortality will remain a constant threat. [source] The angiosperm radiation revisited, an ecological explanation for Darwin's ,abominable mystery'ECOLOGY LETTERS, Issue 9 2009Frank Berendse Abstract One of the greatest terrestrial radiations is the diversification of the flowering plants (Angiospermae) in the Cretaceous period. Early angiosperms appear to have been limited to disturbed, aquatic or extremely dry sites, suggesting that they were suppressed in most other places by the gymnosperms that still dominated the plant world. However, fossil evidence suggests that by the end of the Cretaceous the angiosperms had spectacularly taken over the dominant position from the gymnosperms around the globe. Here, we suggest an ecological explanation for their escape from their subordinate position relative to gymnosperms and ferns. We propose that angiosperms due to their higher growth rates profit more rapidly from increased nutrient supply than gymnosperms, whereas at the same time angiosperms promote soil nutrient release by producing litter that is more easily decomposed. This positive feedback may have resulted in a runaway process once angiosperms had reached a certain abundance. Evidence for the possibility of such a critical transition to angiosperm dominance comes from recent work on large scale vegetation shifts, linking long-term field observations, large scale experiments and the use of simulation models. [source] Effect of habitat fragmentation on spawning migration of brown trout (Salmo trutta L.)ECOLOGY OF FRESHWATER FISH, Issue 3 2006C. Gosset Abstract , Human-induced habitat alteration is one of the main causes of the decline of freshwater fish populations. The watershed of the River Bidasoa (Spain) is an example of heavily fragmented habitat. The local brown trout (Salmo trutta L.) population is disturbed, with evidence of poor recruitment as well as low adult densities in the main stem. Forty male and female adult migratory trout were tagged with external or internal radio transmitters and released. Fixed stations with data loggers and mobile antennae were used with daily surveys to track fish movements during the migration and spawning period (3 months). Migration distances did not exceed 10 km, and half of the fish never entered a tributary in the study area. Fragmentation because of weirs on the main stem apparently prevented fish from reaching their spawning destination. Fish that entered the tributaries were first confronted with an accessibility problem because of low discharge. However, each fish chose one tributary, without making attempts to run up in other tributaries. Once in the tributary, fish were restrained in their upstream movements by dams. The study area appeared to be isolated from the vast upper part of the watershed. Within the study area, upper parts of tributaries also seemed strongly disconnected from the main stem. This study illustrates the negative impact of river fragmentation on S. trutta migration pattern. Population sustainability can be directly affected through the low availability of spawning grounds for migratory fish. Long-term effects of fragmentation may cause reproductive isolation within watersheds, which in the case of trout also means isolated phenotypic population units. [source] Effects of fires on butterfly assemblages in lowland dipterocarp forest in East KalimantanENTOMOLOGICAL SCIENCE, Issue 2 2007Toshiya HIROWATARI Abstract The post-fire butterfly fauna in lowland dipterocarp forest of the Bukit Soeharto Education Forest (BSEF), East Kalimantan, Indonesia, was assessed during the period November 1998,April 2000 by means of consecutive Malaise trap samples, with supplementary field observations for March,April 1999. A total of 514 butterflies belonging to 61 species and representing six families were caught in the traps. Melanitis leda (Nymphalidae: Satyrinae), Charaxes bernardus (Nymphalidae: Charaxinae), and Danaus genutia (Nymphalidae: Danainae) were the species most frequently caught (60, 52 and 47 individuals, respectively), representing 31% of the total. These three species are generalists and "disturbance indicators" for tropical rainforest, being characteristic of disturbed or secondary forests, being distributed widely, and having larvae that feed on a wide range of host plants. In contrast, other species, such as Trogonoptera brookiana and Troides amphrysus, were recorded before the fires but were not recorded again afterwards. The pre- and post-fire butterfly fauna of East Kalimantan were compared on the basis of butterfly specimens deposited in the Tropical Rain Forest Research Center that were collected in and around the Bukit Soeharto Education Forest before the fires (1988,1995). On the basis of the post-fire survey, based on Malaise trap samples and field observations, only 43% of the butterfly species (not including Lycaenidae and Hesperiidae) were confirmed to have persisted. The data suggest that refugia that are not affected by fire are necessary for the conservation of specialist butterflies, as well as many other forms of wildlife. [source] Chronic toxicity of lead to three freshwater invertebrates,Brachionus calyciflorus, Chironomus tentans, and Lymnaea stagnalisENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2006Martin Grosell Abstract Chronic lead (Pb) toxicity tests with Brachionus calyciflorus, Chironomus tentans, and Lymnaea stagnalis were performed in artificial freshwaters. The no-observable-effect concentration (NOEC), lowest-observable-effect concentration (LOEC), and calculated 20% effect concentration (EC20) for the rotifer B. calyciflorus were 194, 284, and 125 ,g dissolved Pb/L, respectively. The midge C. tentans was less sensitive, with NOEC and LOEC of 109 and 497 ,g dissolved Pb/L, respectively, and the snail L. stagnalis exhibited extreme sensitivity, evident by NOEC, LOEC, and EC20 of 12, 16, and <4 ,g dissolved Pb/L, respectively. Our findings are presented in the context of other reports on chronic Pb toxicity in freshwater organisms. The L. stagnalis results are in agreement with a previous report on pulmonate snails and should be viewed in the context of current U.S. Environmental Protection Agency (U.S. EPA) hardness adjusted water quality criteria of 8 ,g Pb/L. The present findings and earlier reports indicate that freshwater pulmonate snails may not be protected by current regulatory standards. Measurements of whole-snail Na+ and Ca2+ concentrations following chronic Pb exposure revealed that Na+ homeostasis is disturbed by Pb exposure in juvenile snails in a complicated pattern, suggesting two physiological modes of action depending on the Pb exposure concentration. Substantially reduced growth in the snails that exhibit very high Ca2+ requirements may be related to reduced Ca2+ uptake and thereby reduced shell formation. [source] Male Competition over Access to Females in a Spider with Last-Male Sperm PrecedenceETHOLOGY, Issue 5 2003Daniela Schaefer Agonistic behaviour between male cellar spiders (Pholcus phalangioides) was investigated to test whether (1) size difference determines which male achieves access to the female, (2) males are able to monopolize access to the female until egg laying and whether (3) female resource value increases before egg laying because of last-male sperm precedence. We further investigated whether (4) there is variation in time and energy spent on courtship and copulation depending on the degree of sperm competition, i.e. with or without rival present. In three experimental settings we introduced two males of either different or similar sizes, or a single male to a female. The mating units were constantly video-observed until the females produced their first egg sac. Experience, ownership and female resource value in terms of body size was controlled. Our results show that larger males achieve almost exclusive access to females. Size symmetrical settings resulted in increased fighting activity and duration but dominance did not influence mating success. If copulations were disturbed by the rival male, copulations were terminated earlier in symmetrical settings compared with asymmetrical settings. In 94.8% of trials only one copulation took place, suggesting that the copulating male successfully monopolized access to the female. Males confronted with a rival copulated longer but courted significantly shorter than lone males. Although the last male to copulate sires 88% of the offspring in P. phalangioides, neither fighting nor courtship activity increased before the female laid a batch of eggs. This suggests that males have no indication of the timing of oviposition. [source] Chemical Alarm Signals Enhance Survival of Brook Charr (Salvelinus fontinalis) During Encounters with Predatory Chain Pickerel (Esox niger)ETHOLOGY, Issue 11 2001Reehan S. Mirza A diversity of aquatic organisms release chemical alarm signals when attacked or captured by a predator. These alarm signals are thought to warn other conspecifics of danger and, consequently, may benefit receivers by increasing their survival. Here we experimentally investigated the differences in behaviour and survival of hatchery-reared juvenile brook charr Salvelinus fontinalis that had been exposed to either brook charr skin extract (experimental treatment) or a control of swordtail skin extract (control treatment). Charr exposed to conspecific skin extract exhibited a significant reduction in movement and/or altered their foraging behaviour in the laboratory when compared with charr exposed to swordtail skin extract. We also exposed charr to either water conditioned by a single brook charr disturbed by a predatory bird model or water conditioned by a single undisturbed brook charr. Charr exposed to disturbance signals reduced activity significantly more than charr exposed to chemical stimuli from undisturbed charr. These results demonstrate the existence of both damage-released alarm signals and disturbance signals in brook charr. Wild brook charr also responded to damage-released alarm cues under natural conditions. Charr avoided areas of a stream with minnow traps labelled with conspecific alarm cues vs. control cues. During staged encounters with chain pickerel Esox niger in the laboratory, predator-naive charr fry were better able to evade the predator if they were previously warned by an alarm signal, thus suggesting a survival benefit to receivers. Collectively, these results demonstrate that the presence of alarm signals in brook charr has important implications for understanding predator,prey interactions. [source] Fatty acid incorporation in endothelial cells and effects on endothelial nitric oxide synthaseEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 9 2007S. Couloubaly Abstract Background The nature of fatty acids provided by the diet as well as plasma lipid metabolism can modify the composition and properties of plasma membrane and thus the activity of membrane proteins. In humans, as well as in experimental models, diabetes is associated with both an alteration in serum lipid profile and a documented endothelial dysfunction. This in vitro study investigated on an immortalized human endothelial cell line (EA.hy 926) the specific effects of several free fatty acids (FFAs) on the composition of cellular membranes and the regulation of endothelial nitric oxide synthase (eNOS). Materials and methods 0·1% of lipid deprived serum was added to the incubation medium with 25 mm glucose in order to study the effects of individual fatty acids: myristic acid, palmitic acid, stearic acid, oleic acid or linoleic acid at 100 µm bound with albumin. The effects of the FFAs on the endothelial nitric oxide synthase were investigated on mRNA level by quantitative PCR, on protein level and Ser1177 phosphorylation by Western blot and on enzymatic activity on living cells using radiolabelled arginine. Results Free linoleic acid increased the membrane content in n-6 fatty acids (mainly C18: n-6 and its metabolites) with a decrease in saturated and monounsaturated fatty acids. These conditions decreased the basal eNOS activity and reduced the phosphorylation of eNOS-Ser1177 due to activation by histamine. Free palmitic acid enriched the membranes with 16 : 0 with a slight decrease in monounsaturated fatty acids. These conditions increased eNOS activation without increasing Ser1177 phosphorylation upon histamine activation. The addition of the other FFAs also resulted in modifications of membrane composition, which did not to affect eNOS-Ser1177 phosphorylation. Conclusion Among the fatty acids used, only modification of the membrane composition due to linoleic acid supply disturbed the basal enzymatic activity and Ser1177 phosphorylation of eNOS in a way that limited the role of histamine activation. Linoleic acid might involve the dysfunction of both eNOS basal activity and its phosphorylation status and may then contribute to an impaired vasodilatation in vivo. [source] Compound heterozygosity of two missense mutations in the NADH-cytochrome b5 reductase gene of a Polish patient with type I recessive congenital methaemoglobinaemiaEUROPEAN JOURNAL OF HAEMATOLOGY, Issue 6 2003Dorota Grabowska Abstract: A case of type I methaemoglobinaemia observed in a Polish subject with compound heterozygosity for two mutations in the reduced nicotinamide adenine dinucleotide (NADH) cytochrome b5 reductase (b5R) gene is described. One is a novel mutation 647T,C which leads to substitution of isoleucine by threonine at position 215 (I215T). This maternal mutation was found in several family members. A previously known mutation, 757G,A, leads to the replacement of valine by methionine at position 252 (V252M). The latter mutation was found also in the father and one of the two brothers. The effects of these mutations were analysed on a model of the human b5R protein obtained by homology modelling. Although both amino acid substitutions are located in the NADH-binding domain, the whole protein structure, especially the region between the flavin adenine dinucleotide and NADH-binding domains, is disturbed. The structural changes in the I215T mutant are less prominent than those in the V252M mutant. We presume that the 647T,C mutation is a type I mutation, however, it has not been observed in the homozygous state. [source] An exploration of anger phenomenology in multiple sclerosisEUROPEAN JOURNAL OF NEUROLOGY, Issue 12 2009U. Nocentini Background and purpose:, Multiple sclerosis (MS) patients are often emotionally disturbed. We investigated anger in these patients in relation to demographic, clinical, and mood characteristics. Patients and methods:, About 195 cognitively unimpaired MS patients (150 relapsing,remitting and 45 progressive) were evaluated with the State Trait Anger Expression Inventory, the Chicago Multiscale Depression Inventory, and the State Trait Anxiety Inventory. The patients' anger score distribution was compared with that of the normal Italian population. Correlation coefficients among scale scores were calculated and mean anger scores were compared across different groups of patients by analysis of variance. Results:, Of the five different aspects of anger, levels of withheld and controlled Anger were respectively higher and lower than what is expected in the normal population. Although anger was correlated with anxiety and depression, it was largely independent from these mood conditions. Mean anger severity scores were not strongly influenced by individual demographic characteristics and were not higher in more severe patients. Conclusions:, The presence of an altered pattern of anger, unrelated to the clinical severity of MS, suggests that anger is not an emotional reaction to disease stress. An alteration of anger mechanisms might be a direct consequence of the demyelination of the connections among the amygdale, the basal ganglia and the medial prefrontal cortex. [source] Impaired formation of the inner retina in an AChE knockout mouse results in degeneration of all photoreceptorsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2004Afrim H. Bytyqi Abstract Blinding diseases can be assigned predominantly to genetic defects of the photoreceptor/pigmented epithelium complex. As an alternative, we show here for an acetylcholinesterase (AChE) knockout mouse that photoreceptor degeneration follows an impaired development of the inner retina. During the first 15 postnatal days of the AChE,/, retina, three major calretinin sublaminae of the inner plexiform layer (IPL) are disturbed. Thereby, processes of amacrine and ganglion cells diffusely criss-cross throughout the IPL. In contrast, parvalbumin cells present a nonlaminar IPL pattern in the wild-type, but in the AChE,/, mouse their processes become structured within two ,novel' sublaminae. During this early period, photoreceptors become arranged regularly and at a normal rate in the AChE,/, retina. However, during the following 75 days, first their outer segments, and then the entire photoreceptor layer completely degenerate by apoptosis. Eventually, cells of the inner retina also undergo apoptosis. As butyrylcholinesterase (BChE) is present at a normal level in the AChE,/, mouse, the observed effects must be solely due to the missing AChE. These are the first in vivo findings to show a decisive role for AChE in the formation of the inner retinal network, which, when absent, ultimately results in photoreceptor degeneration. [source] Serially concatenated continuous phase modulation with symbol interleavers: performance, properties and design principlesEUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 4 2006Ming Xiao Serially concatenated continuous phase modulation (SCCPM) systems with symbol interleavers are investigated. The transmitted signals are disturbed by additive white Gaussian noise (AWGN). Compared to bit interleaved SCCPM systems, this scheme shows a substantial improvement in the convergence threshold at the price of a higher error floor. In addition to showing this property, we also investigate the underlying reason by error event analysis. In order to estimate bit error rate (BER) performance, we generalise traditional union bounds for a bit interleaver to this non-binary interleaver. For the latter, both the order and the position of permuted non-zero symbols have to be considered. From the analysis, some principal properties are identified. Finally, some design principles are proposed. Our paper concentrates on SCCPM, but the proposed analysis methods and conclusions can be widely used in many other systems such as serially concatenated trellis coded modulation (SCTCM) et cetera. Copyright © 2006 AEIT [source] | |||||||||||||||||||||||||||||||||||||||||||||||||