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Gradual Decrease (gradual + decrease)
Selected AbstractsPatch Occupancy and Potential Metapopulation Dynamics of Three Forest Mammals in Fragmented Afromontane Forest in South AfricaCONSERVATION BIOLOGY, Issue 4 2000Michael J. Lawes We recorded patch occupancy of blue duiker ( Philantomba monticola), tree hyrax ( Dendrohyrax arboreus), and samango monkey (Cercopithecus mitis labiatus) in 199 forest patches. Their rarity is ascribed to the fragmentation and destruction of their forest habitat. Incidence functions, derived from presence and absence data, were formulated as generalized linear models, and environmental effects were included in the fitted logistic models. The small and mostly solitary hyrax and duiker persisted in smaller patches than the large and social monkey. Although this result follows expectations based on relative home-range sizes of each species, the incidence probability of the samango monkey was invariant with increasing isolation, whereas a gradual decrease with increasing isolation was observed for the hyrax and duiker. Group dynamics may inhibit dispersal and increase the isolation effect in social species such as samango monkeys. A mainland-island metapopulation model adequately describes patterns of patch occupancy by the hyrax and duiker, but the monkeys' poor dispersal ability and obvious area-dependent extirpation suggest that they exist in transient, nonequilibrium (declining) metapopulations. Through identification of large forest patches for careful protection and management, the survival of all three species,especially the monkey,could be prolonged. Because no functional metapopulation may exist for the monkey, however, this is an emergency measure. For the duiker and hyrax, larger patches should form part of a network of smaller and closer patches in a natural matrix. Resumen: Investigamos la persistencia de tres mamíferos forestales raros de tamaño mediano (2,9 kg) en los bosques fragmentados de cinturón de niebla Podocarpus en la región central de la provincia KwaZulu-Natal, Sudáfrica. Registramos la ocupación del duiker azul ( Philantomba monticola), el hyrax arborícola ( Dendrohyrax arboreus) y el mono samango (Cercopithecus mitis labiatus) en 199 parches forestales. Su rareza se atribuye a la fragmentación y destrucción de su hábitat forestal. Las funciones de incidencia, derivadas de datos de presencia y ausencia, fueron formuladas como modelos lineales generalizados, y los efectos ambientales fueron incluidos en los modelos logísticos ajustados. Los pequeños y mayormente solitarios hyrax y duiker persistieron en parches más pequeños que los monos, que son más grandes y más sociables. A pesar de que este resultado obedece a expectativas basadas en tamaños de rango de hogar relativos de cada especie, la probabilidad de incidencia del mono samango no cambió con un incremento en el aislamiento, mientras que una disminución gradual al crecer el aislamiento se observó en hyrax y duiker. Las dinámicas de grupos podrían inhibir la dispersión e incrementar el efecto de aislamiento en especies sociables como lo es el mono samango. Un modelo de metapoblación continente-isla describe adecuadamente los patrones de la ocupación de parches por hyrax y duiker; sin embargo, la pobre capacidad de dispersión de los monos y la obvia extirpación área-dependente sugiere que estos existen en metapoblaciones transitorias, desequilibradas (en disminución). Mediante la identificación de parches forestales grandes para la protección y manejo cuidadosos, la supervivencia de las tres especies ( pero especialmente la de los monos) podría ser prolongada. Sin embargo, debido a que no existen metapoblaciones funcionales de monos, esta es una medida de emergencia. Para el duiker y el hyrax, los parches grandes deberán formar parte de una red de parches más pequeños y más cercanos en una matriz natural. [source] Historic and contemporary sediment transfer in an upland Pennine catchment, UKEARTH SURFACE PROCESSES AND LANDFORMS, Issue 14 2008V. J. Holliday Abstract A sediment budget for an upland catchment,reservoir system at Burnhope Reservoir, North Pennines, UK has been developed. This provides a framework for quantifying historic and contemporary sediment yields and drainage basin response to disturbance from climate change and human activities in the recent past. Bathymetric survey, core sampling, 137Cs dating and aerial photographs have been used to assess sediment accumulation in the reservoir. The average reservoir sedimentation rate is 1·24 cm yr,1 (annual sediment yield 33·3 t km,2 yr,1 ± 10%, trap efficiency 92%). Mean annual reservoir sedimentation over the 67 year period has been estimated at 592 t ± 10%. Inputs of suspended sediment from direct catchwater streams account for 54% of sediment supply to the budget (best estimate yield of 318 t yr,1 ± 129%), while those from actively eroding reservoir shorelines contribute 328 t yr,1 ± 92%. Sediment yield estimates from stream monitoring and reservoir sedimentation are an order of magnitude lower than those reported from South Pennine reservoirs of comparable drainage basin area. Analysis of historical rainfall series for the catchment shows fluctuations in winter and summer rainfall patterns over the past 62 years. From 1976 to 1998 there has been a diverging trend between winter and summer rainfall, with a large increase in winter and a gradual decrease in summer totals. Periods of maximum variation occur during the summer drought events of the late 1970s, early 1980s and mid-1990s. Analysis of the particle size of core sediments highlights abrupt increases in sand-sized particles in the top 20 cm of the core. Based on the 137Cs chronology, these layers were deposited from the late 1970s onwards and relate to these diverging rainfall records and rapidly fluctuating reservoir levels. This provides evidence of potential sediment reworking within the reservoir by rapid water-level rise after drought. Copyright © 2008 John Wiley & Sons, Ltd. [source] Nutrient limitations during the biofiltration of methyl isoamyl ketoneENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 1 2005Hyun-Keun Son With biofiltration, both organic and inorganic compounds that are toxic to humans and volatile organic compounds from a variety of industrial and public sector sources have been effectively removed. During the initial stage of the acclimation period, the removal capacity of the biofilter is primarily attributed to the adsorption capacity of the media. The adsorption capacity of different types of biofilter media was studied. MIAK (methyl isoamyl ketone), which is one of the major air pollutants in painting operations, was used as the target air pollutant for the biofiltration experiments. All the materials tested exhibited very poor adsorption capacity for MIAK. The effect of nutrient limitation was also evaluated. A gradual decrease of removal capacity was observed under the nutrient-limited environment. When nutrient was provided to the biofilter, the removal capacity increased from 55 to 93% in 3 days. A nutrient ratio of chemical oxygen demand (COD):N:P = 200:4:1 was sufficient for the removal of volatile organic compounds from the polluted air stream. © 2004 American Institute of Chemical Engineers Environ Prog, 2004 [source] Tributyltin uptake and depuration in Hyalella azteca: Implications for experimental designENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2004Adrienne J. Bartlett Abstract The purpose of this study was to address four aspects of the kinetics of tributyltin (TBT) in the freshwater amphipod Hyalella azteca: time to steady state, route of uptake, depuration rates, and effect of gut clearance. The amphipods accumulated TBT rapidly, reaching steady state within 14 d. Body concentrations were similar between caged and sediment-exposed animals, indicating that the primary route of uptake is via dissolved TBT. However, the rate of uptake was significantly higher in sediment-exposed amphipods. During depuration, body concentrations of TBT exhibited a biphasic decline, with a stronger decrease over the first 24 h that is attributed primarily to gut clearance, followed by a more gradual decrease most likely due to excretion from the body. Gut contents contributed significantly to body concentrations of TBT, accounting for 30% of the initial total body burden in sediment-exposed amphipods. Half-lives of TBT in gut-cleared H. azteca were 8 d and 14 d for amphipods exposed to spiked water and spiked sediment, respectively. The results of this study have significant implications in the experimental design and interpretation of studies involving the effects of TBT in H. azteca. [source] On the distribution of wildfire sizesENVIRONMETRICS, Issue 6 2003Frederic Paik Schoenberg Abstract A variety of models for the wildfire size distribution are examined using data on Los Angeles County wildfires greater than 100 acres between 1950 and 2000. In addition to graphs and likelihood criteria, Kolmogorov,Smirnoff and Cramer,von Mises statistics are used to compare the models. The tapered Pareto distribution appears to fit the data quite well and offers some advantages over the untapered Pareto distribution, while alternatives including the lognormal, half-normal, exponential and extremal distributions fit poorly. The size distribution appears to be quite stable over the examination period, though inspection of the transformed wildfire sizes for the tapered Pareto reveals some limited trend in the residuals, indicating a very slight gradual decrease in the average fire size in Los Angeles County over these 50 years. Copyright © 2003 John Wiley & Sons, Ltd. [source] Metal Ion Complementarity: Effect of Ring-Size Variation on the Conformation and Stability of Lead(II) and Cadmium(II) Complexes with Pendant-Armed CrownsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 15 2007Martín Regueiro-Figueroa Abstract The binding tendencies of the pendant-armed crown ethers L1,L3 [L1 = N,N, -bis(benzimidazol-2-ylmethyl)-1,7-diaza-12-crown-4, L2 = N,N, -bis(benzimidazol-2-ylmethyl)-1,10-diaza-15-crown-5) and L3 = N,N, -bis(benzimidazol-2-ylmethyl)-4,13-diaza-18-crown-6] towards PbII and CdII have been investigated. The X-ray crystal structure of [Cd(L3)](ClO4)2·EtOH shows that, in the solid state, the CdII ion is eight-coordinate and fits quite well into the crown hole, favouring an anti arrangement of the organic receptor. NMR measurements recorded in acetonitrile solution indicate that increasing the crown size induces a conformational change in the series of CdII complexes. The conformation goes from a syn arrangement for L1 to an anti arrangement for L3, passing through a syn [lrarr2] anti equilibrium in the complex derived from L2. On the contrary, no conformational change was observed for the corresponding PbII complexes, which have a syn conformation in all cases. These results have been confirmed by means of density functional theory (DFT) calculations performed by using the B3LYP model. The binding constants obtained from UV/Vis titration experiments in DMSO solution demonstrate that a decrease in the crown size provokes a 102 -fold enhancement of the stability for this series of CdII complexes, whereas for PbII a gradual decrease of the binding constants is observed. Receptor L1 shows a certain degree of selectivity for CdII over PbII, with a selectivity factor > 102. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] The relationship between thermal stability and pH optimum studied with wild-type and mutant Trichoderma reesei cellobiohydrolase Cel7AFEBS JOURNAL, Issue 5 2003Harry Boer The major cellulase secreted by the filamentous fungus Trichoderma reesei is cellobiohydrolase Cel7A. Its three-dimensional structure has been solved and various mutant enzymes produced. In order to study the potential use of T. reesei Cel7A in the alkaline pH range, the thermal stability of Cel7A was studied as a function of pH with the wild-type and two mutant enzymes using different spectroscopic methods. Tryptophan fluorescence and CD measurements of the wild-type enzyme show an optimal thermostability between pH 3.5,5.6 (Tm, 62 ± 2 °C), at which the highest enzymatic activity is also observed, and a gradual decrease in the stability at more alkaline pH values. A soluble substrate, cellotetraose, was shown to stabilize the protein fold both at optimal and alkaline pH. In addition, unfolding of the Cel7A enzyme and the release of the substrate seem to coincide at both acidic and alkaline pH, demonstrated by a change in the fluorescence emission maximum. CD measurements were used to show that the five point mutations (E223S/A224H/L225V/T226A/D262G) that together result in a more alkaline pH optimum [Becker, D., Braet, C., Brumer, H., III, Claeyssens, M., Divne, C., Fagerström, R.B., Harris, M., Jones, T.A., Kleywegt, G.J., Koivula, A., et al. (2001) Biochem. J.356, 19,30], destabilize the protein fold both at acidic and alkaline pH when compared with the wild-type enzyme. In addition, an interesting time-dependent fluorescence change, which was not observed by CD, was detected for the pH mutant. Our data show that in order to engineer more alkaline pH cellulases, a combination of mutations should be found, which both shift the pH optimum and at the same time improve the thermal stability at alkaline pH range. [source] An ex vivo swine tracheal organ culture for the study of influenza infectionINFLUENZA AND OTHER RESPIRATORY VIRUSES, Issue 1 2010Sandro F. Nunes Background The threat posed by swine influenza viruses with potential to transmit from pig populations to other hosts, including humans, requires the development of new experimental systems to study different aspects of influenza infection. Ex vivo organ culture (EVOC) systems have been successfully used in the study of both human and animal respiratory pathogens. Objectives We aimed to develop an air interface EVOC using pig tracheas in the study of influenza infection demonstrating that tracheal explants can be effectively maintained in organ culture and support productive influenza infection. Methods Tracheal explants were maintained in the air interface EVOC system for 7 days. Histological characteristics were analysed with different staining protocols and co-ordinated ciliary movement on the epithelial surface was evaluated through a bead clearance assay. Explants were infected with a swine H1N1 influenza virus. Influenza infection of epithelial cells was confirmed by immunohistochemistry and viral replication was quantified by plaque assays and real-time RT-PCR. Results Histological analysis and bead clearance assay showed that the tissue architecture of the explants was maintained for up to 7 days, while ciliary movement exhibited a gradual decrease after 4 days. Challenge with swine H1N1 influenza virus showed that the EVOC tracheal system shows histological changes consistent with in vivo influenza infection and supported productive viral replication over multiple cycles of infection. Conclusion The air interface EVOC system using pig trachea described here constitutes a useful biological tool with a wide range of applications in the study of influenza infection. [source] Spatial and temporal variabilities of rainfall in tropical South America as derived from Climate Prediction Center merged analysis of precipitationINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 2 2002H. Matsuyama Abstract We investigated the spatial and temporal variabilities of Climate Prediction Center merged analysis of precipitation (CMAP) in tropical South America from 1979 to 1998. First, we validated CMAP using other hydrometeorological data. In comparison with the high-density precipitation data of the Global Historical Climatology Network (GHCN) Ver. 2, CMAP reproduces the spatial pattern well, although it underestimates (overestimates) heavy (light) precipitation. CMAP also reproduces the interannual variability well, compared with the discharge data of the River Amazon. Next, we applied the rotated empirical orthogonal function (REOF) to CMAP after subtracting the annual cycle. Simultaneous and lag correlations were calculated among the scores of REOFs 1 to 4, the southern oscillation index, and the dipole index of the Atlantic. REOF 1 (15%) represents the north,south pattern that exhibits the maximum precipitation in the summer hemisphere. REOF 2 (12%) indicates the gradual decrease of precipitation in the northern part of tropical South America, reflecting the effect of the Atlantic. REOF 3 (11%) exhibits an east,west pattern related to El Niño. In REOF 4 (7%), the centre of the factor loading is located in Colombia, and the score jumps abruptly around 1985,86. The Lepage test detected the abrupt increase of CMAP in 1985,86 around Colombia. Since such a jump is not found in GHCN Ver. 2, the discontinuous changes of CMAP and REOF 4 around 1985,86 are artificial and peculiar to CMAP. In this region, CMAP should be applied with caution when evaluating recent trends and the interannual variability. The importance of the abrupt increase of precipitation around Colombia is also addressed. Copyright © 2002 Royal Meteorological Society. [source] Cell Lysis of Cyanobacteria and Its Implications for Nutrient DynamicsINTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 3 2010Linlin Ye Abstract The dynamics of nutrients, such as phosphorus, nitrogen, and carbohydrates, during cyanobacteria cell lysis was investigated under darkness incubation in the laboratory. The cell lysis rate of cyanobacteria sampled from Lake Taihu was measured using an esterase assay. Based on particulate esterase activity, the calculated cyanobacteria lysis rate was 0.094 d,1. During 30 days of darkness incubation, Chlorophyll a concentration decreased from 56 ,g L,1 to 2.0 ,g L,1. Parallel to this, total particulate carbohydrate concentration decreased rapidly. The fluctuation of dissolved organic carbon concentration was a function of the production of non-carbohydrate by cyanobacteria and the decomposition of carbohydrate by bacteria. Total dissolved carbohydrates and dissolved polysaccharides concentrations showed a similar pattern, declining at the beginning of the experiment and keeping relatively stable, thereafter. In contrast, the concentration of dissolved monosaccharides remained constant during the entire process. The concentrations of NH4+ and PO43, increased at the early stage, and then decreased afterwards. A gradual decrease in NO3, concentration after day 8 indicated that anaerobic conditions might be produced during the cell lysis process. The present results demonstrated cyanobacteria cell lysis has a big influence on the nutrient status of the surrounding water. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Enantioselective Hydrogenation of N -Acetyldehydroamino Acids over Supported Palladium CatalystsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 3 2007György Szöll Abstract The enantioselective hydrogenation of two N -acetyldehydroamino acids over Cinchona alkaloid-modified, supported palladium catalysts has been studied. Moderate enantioselectivities, up to 36,%, were obtained in the hydrogenation of 2-acetamidocinnamic acid over cinchonidine-modified Pd/TiO2 under low hydrogen pressure. Increase in the pressure or use of benzylamine as additive led to a gradual decrease in the enantiomeric excess and eventually inversion of the sense of the enantioselectivity. On the contrary, the optical purity of the product resulting from the hydrogenation of 2-acetamidoacrylic acid was significantly increased by addition of benzylamine to the reaction mixture. Enantiomeric excess values up to 58,% and 60,% were obtained over Pd/Al2O3 modified by cinchonidine and cinchonine, respectively. These optical purities are the best obtained in the hydrogenation of dehydroamino acid derivatives over chirally modified heterogeneous metal catalysts. [source] Temporal expression changes during differentiation of neural stem cells derived from mouse embryonic stem cellJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 3 2004Joon-Ik Ahn Abstract Temporal analysis in gene expression during differentiation of neural stem cells (NSCs) was performed by using in-house microarrays composed of 10,368 genes. The changes in mRNA level were measured during differentiation day 1, 2, 3, 6, 12, and 15. Out of 10,368 genes analyzed, 259 genes were up-regulated or down-regulated by 2-fold or more at least at one time-point during differentiation, and were classified into six clusters based on their expression patterns by K-means clustering. Clusters characterized by gradual increase have large numbers of genes involved in transport and cell adhesion; those which showed gradual decrease have much of genes in nucleic acid metabolism, cell cycle, transcription factor, and RNA processing. In situ hybridization (ISH) validated microarray data and it also showed that Fox M1, cyclin D2, and CDK4 were highly expressed in CNS germinal zones and ectonucleotide pyrophosphatase/phosphodiesterase 2 (Enpp2) was highly expressed in choroid plexus where stem/progenitor cells are possibly located. Together, this clustering analysis of expression patterns of functionally classified genes may give insight into understanding of CNS development and mechanisms of NSCs proliferation and differentiation. © 2004 Wiley-Liss, Inc. [source] Dynamics of mucosal dimensions after root coverage with a bioresorbable membraneJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 1 2000Hans-Peter Müller Abstract Background: So far, the clinical effects of the placement of a resorbable membrane for guided tissue regeneration have not been studied in humans in great detail. The dynamics of the resorptive processes, in particular, appear to be rather speculative. In the present longitudinal study, specific alterations of the dimensions of the dentogingival mucosa were explored after surgical root coverage by using a bioresorbable membrane and a coronally-repositioned flap. Methods: The study population consisted of 14 patients with a total of 31 predominantly shallow, Miller class I, II or III recessions. The thickness of the masticatory and lining mucosa before and after surgical intervention was measured with an ultrasonic device. Results: Mean (±sd) recession depth and width were 2.85±1.29 and 4.46±1.14 mm, respectively. After 12 months, 51±29% of the recession depth (p<0.001) and 13±35% of its width (n.s.) were covered. Root coverage seems to be rather defect-type sensitive with best results obtained at canines with relatively shallow recessions. Mucosal thickness was considerably increased after surgery with a gradual decrease during the following 9 months. Thus, thickness of the marginal tissue rose from 0.82±0.27 mm to 1.49±0.54 mm 3 months after placement of the membrane (p<0.001). After 12 months, a mean thickness of 1.03±0.40 mm was observed (p<0.001). Even more pronounced alterations were noted for the alveolar lining mucosa with a threefold increase of thickness 3 months after surgery and a gradual decrease to about 1 mm after 12 months. Conclusions: The present results point to the considerable space making capacity of the bioresorbable membrane which probably allows for the ingrowth of a granulation tissue derived from the underlying structures. The gradual decline in mucosal thickness between months 6 and 9 after surgery may be paralleled by the maturation of the granulation tissue while complete resorption of the membrane had been accomplished. [source] Sonographic assessment of uterine and ovarian development in normal girls aged 1 to 12 yearsJOURNAL OF CLINICAL ULTRASOUND, Issue 9 2008Maria Badouraki MD Abstract Purpose. To provide normal references of sonographic uterine and ovarian size in girls aged 1,12 years. Method. Ninety-nine girls were enrolled in the study (mean age ± SD, 6.9 ± 2.4 years [range, 1,12 years]). Pubertal status was classified according to Tanner staging, whereas for height and weight assessment a standard stadiometer and weight scale were employed. All subjects underwent pelvic sonographic examination for the measurement of uterine length, volume, ratio of anteroposterior diameter at the fundus divided by the anteroposterior diameter at the cervix (fundal,cervical [F/C] ratio), and ovarian volume and morphology. Results. A gradual increase with age was observed in all uterine and ovarian measurements. Cubic model analysis provided the best curve estimation for uterine length, uterine volume, and ovarian volume in relation to age. Uterine length, uterine volume, ovarian volume and F/C ratio were significantly correlated to both age and height. With respect to ovarian morphology, there was a gradual decrease in frequency of the homogeneous and the paucicystic appearances with increasing age. The macrocystic appearance was observed after the age of 6 years, and its frequency increased gradually with age. Conclusion. There is a continuous increase in size of internal female genitalia from early childhood until the onset of puberty. We have provided reference percentile charts of normal uterine length, uterine volume, and ovarian volume in girls aged 1,12 years. © 2008 Wiley Periodicals, Inc. J Clin Ultrasound, 2008 [source] The P,T path of the ultra-high pressure Lago Di Cignana and adjoining high-pressure meta-ophiolitic units: insights into the evolution of the subducting Tethyan slabJOURNAL OF METAMORPHIC GEOLOGY, Issue 3 2009C. GROPPO Abstract The Lago di Cignana ultra-high-pressure unit (LCU), which consists of coesite,eclogite facies metabasics and metasediments, preserves the most deeply subducted oceanic rocks worldwide. New constraints on the prograde and early retrograde evolution of this ultra-high pressure unit and adjoining units provide important insights into the evolution of the Piemontese,Ligurian palaeo-subduction zone, active in Paleocene,Eocene times. In the LCU, a first prograde metamorphic assemblage, consisting of omphacite + Ca-amphibole + epidote + rare biotite + ilmenite, formed during burial at estimated P < 1.7 GPa and 350 < T < 480 °C. Similar metamorphic conditions of 400 < T < 650 °C and 1.0 < P < 1.7 GPa have been estimated for the meta-ophiolitic rocks juxtaposed to the LCU. The prograde assemblage is partially re-equilibrated into the peak assemblage garnet + omphacite + Na-amphibole + lawsonite + coesite + rutile, whose conditions were estimated at 590 < T < 605 °C and P > 3.2 GPa. The prograde path was characterized by a gradual decrease in the thermal gradient from ,9,10 to ,5,6 °C km,1. This variation is interpreted as the evidence of an increase in the rate of subduction of the Piemonte,Ligurian oceanic slab in the Eocene. Accretion of the Piemontese oceanic rocks to the Alpine orogen and thermal relaxation were probably related to the arrival of more buoyant continental crust at the subduction zone. Subsequent deformation of the orogenic wedge is responsible for the present position of the LCU, sandwiched between two tectonic slices of meta-ophiolites, named the Lower and Upper Units, which experienced peak pressures of 2.7,2.8 and <2.4 GPa respectively. [source] Nerve growth factor-evoked nociceptor sensitization in pig skin in vivoJOURNAL OF NEUROSCIENCE RESEARCH, Issue 9 2010Roman Rukwied Abstract Peripheral sensitization of skin nociceptors by nerve growth factor (NGF) was explored in pig skin in vivo. As an objective output measure, the area of axon-reflex-mediated erythema was assessed upon mechanical, thermal, chemical, and electrical stimuli delivered at 1, 3, and 7 days after i.d. injection of 1 ,g NGF into the pig's back skin (n = 8). Pretreatment with NGF provoked a sensitization to mechanical (600 mN), thermal (10 sec 49°C) and chemical (15 ,l, pH 3) stimuli that lasted for 7 days. No sensitization, however, was found in response to weak mechanical (100 mN), weak thermal (10 sec 45°C), or electrical stimuli. Irrespective of the skin pretreatment (NGF or PBS vehicle control), the area of electrically induced erythema decreased upon repetition (days 1,7) by 70% (P < 0.05). Sensitization of sensory endings by NGF upon mechanical, heat, and chemical stimuli suggests recruitment of sensory transducer molecules [e.g., TRPV1, acid-sensing ion channels (ASICs)]. In contrast, the gradual decrease in electrically induced erythema over 7 days might be attributable to axonal desensitization and possibly activity-dependent down-regulation of sodium channels. Thus, long-lasting sensitization processes of nociceptor endings or axonal sodium channel desensitization mechanisms can be explored in the pig as a translational experimental animal model. © 2010 Wiley-Liss, Inc. [source] Influence of aging on candidal growth and adhesion regulatory agents in salivaJOURNAL OF ORAL PATHOLOGY & MEDICINE, Issue 6 2001Toyohiro Tanida Abstract: Although oral candidiasis is frequently seen in the elderly, the factors determining candidal growth have insufficiently been explored. Hence, we examined the influence of aging on candidal adhesion and growth-inhibitory agents in saliva in 45 healthy volunteers and 60 patients with oral candidiasis. Both non-stimulated and stimulated salivary flow rates (SFRs) in the healthy controls decreased with aging. A gradual decrease of SFRs with aging was also observed in the patients, and the SFR levels were markedly lower than those in the controls. Although the salivary glucose levels were almost constant in all age groups, secretory immunoglobulin A and lactoferrin levels in saliva were significantly decreased statistically with age, and a marginal age-associated decrease in transferrin levels was also observed. In addition, the generation of superoxide from neutrophils in saliva and their Candida killing activity decreased with age, and these phenomena were more apparent in the patients. Furthermore, a larger number of Candida adhered to oral keratinocytes obtained from the elderly healthy controls than to those obtained from young controls. Correspondingly, keratinocytes from the aged controls showed more concanavalin-A binding sites than those from the young controls. However, oral Candida did not increase with increasing age in the controls, although an age-associated increase of oral Candida was observed in the patients. Taken together, these results indicate that the decreases of SFRs and salivary anti-candidal factors, suppression of salivary neutrophil function and the increase of candidal adhesion sites on keratinocytes predispose elderly individuals to oral candidiasis. [source] DIEL RHYTHM OF ALGAL PHOSPHATE UPTAKE RATES IN P-LIMITED CYCLOSTATS AND SIMULATION OF ITS EFFECT ON GROWTH AND COMPETITION1JOURNAL OF PHYCOLOGY, Issue 4 2002Chi-Yong Ahn Oscillations in the phosphate (Pi) uptake rates for three species of green algae were examined in a P-limited cyclostat. For Ankistrodesmus convolutus Corda and Chlorella vulgaris Beyerinck, the Pi uptake rates increased during the daytime and decreased at night. In contrast, Chlamydomonas sp. exhibited the opposite uptake pattern. Cell densities also oscillated under a light:dark cycle, dividing at a species-specific timing rather than continuously. In general, the cell densities exhibited an inverse relationship with the Pi uptake rates. A competition experiment between A. convolutus and C. vulgaris in a P-limited cyclostat resulted in the dominance of C. vulgaris, regardless of the relative initial cell concentrations. Chlorella vulgaris also dominated in a mixed culture with Chlamydomonas sp., irrespective of the initial seeding ratio and dilution rate. However, Chlamydomonas sp. and A. convolutus coexisted in the competition experiment with gradual decrease of Chlamydomonas sp. when equally inoculated. Mathematical expressions of the oscillations in the Pi uptake rate and species-specific cell division gate were used to develop a simulation model based on the Droop equation. The simulation results for each of the species conformed reasonably well to the experimental data. The results of the competition experiments also matched the competition simulation predictions quite well, although the experimental competition was generally more delayed than the simulations. In conclusion, the model simulation that incorporated the effect of diel rhythms in nutrient uptake clearly demonstrated that species diversity could be enhanced by different oscillation patterns in resource uptake, even under the condition of limitation by the same resource. [source] Isotopic climate record in a Holocene stalagmite from Ursilor Cave (Romania)JOURNAL OF QUATERNARY SCIENCE, Issue 4 2002Bogdan Petroniu Onac Abstract The PU-2 stalagmite from Ursilor Cave provides the first dated Romanian isotope record for the Holocene. The overall growth rate of the speleothem was 3.5 cm kyr,1, corresponding to a temporal resolution of 142 y between each isotope analysis. The ,Hendy' tests indicate that isotopic equilibrium conditions occurred during the formation of PU-2, and hence that it is suitable for palaeoclimatic studies. The relationship between ,18O and temperature was found to be positive. This can be interpreted either as rain-out with distance from the west-northwest ocean source of evaporation or shifts in air mass source with changing North Atlantic Oscillation indices. Applying five U,Th thermal ionisation mass spectrometric (TIMS) dates to a 17.5 cm isotope profile (,18O and ,13C) along the stalagmite growth axis enabled a tentative interpretation of the palaeoclimate signal over the past 7.1 kyr. Spikes of depleted isotopic ,18O values are centred near ca. 7, ca. 5.2 and ca. 4 ka, reflecting cool conditions. The record shows two warm intervals between ca. 3.8 and ca. 3.2 ka (the maximum warmth) and from ca. 2 to ca. 1.4 ka, when the ,18O values were less negative than present. The ,Holocene Climate Optimum' spanning the time interval from ca. 6.8 to ca. 4.4 ka is not well expressed in the PU-2 stalagmite. Individual spikes of lighter ,13C are interpreted as indicative of periods of heavy rainfall, at ca. 7, ca. 5.5, and ca. 3.5 ka. The overall trend to lighter ,13C in the PU-2 stalagmite may reflect a gradual decrease in water,rock interaction. The results demonstrate that the effect of North Atlantic oceanic changes extended to the investigated area. Nevertheless, some differences in temporal correlation and intensity of stable isotopic response to these climatic events have been found, but the exact nature of these differences and the underlying mechanism is yet to be determined. Copyright © 2002 John Wiley & Sons, Ltd. [source] Solvent dependent study of carbonyl vibrations of 3-phenoxybenzaldehyde and 4-ethoxybenzaldehyde by Raman spectroscopy and ab initio calculationsJOURNAL OF RAMAN SPECTROSCOPY, Issue 8 2009Veerabahu Ramakrishnan Abstract A Raman spectroscopy investigation of the carbonyl stretching vibrations of 3-phenoxybenzaldehye (3Phbz) and 4-ethoxybenzaldeheyde (4Etob) was carried out in binary mixtures with different polar and nonpolar solvents. The purpose of this study was twofold: firstly, to describe the interaction of the carbonyl groups of two solute molecules in terms of a splitting in the isotropic and anisotropic components and secondly, to analyze their spectroscopic signatures in a binary mixture. Changes in wavenumber position, variation in the anisotropic shift and full width half maximum were investigated for binary mixtures with different mole fractions of the reference systems. In binary mixtures, the observed increase in wavenumber with solvent concentration does not show linearity, indicating the significant role of molecular interactions on the occurrence of breaking of the self-association of the solute. In all the solvents, a gradual decrease in the anisotropic shift reflects the progressive separation of the coupled oscillators with dilution. ,i(,c), 3Phbz,solvent mixtures, exhibit a gradual decrease with decrease in the concentration of the solute which is an evidence on the influence of micro viscosity on linewidth. For 4Etob, the carbonyl stretching vibration shows two well-resolved components in the Raman spectra, attributed to the presence of two distinct carbonyl groups: hydrogen-bonded and free carbonyl groups. The intensity ratio of the carbonyl stretching vibration of these two types of carbonyl groups is studied to understand the dynamics of solute/solvent molecules owing to hydrogen bond interactions. Ab initio calculations were employed for predicting relevant molecular structures in the binary mixtures arising from intermolecular interactions, and are related to the experimental results. Copyright © 2009 John Wiley & Sons, Ltd. [source] A position-sensitive ionization chamber for XAFS studies at synchrotron sourcesJOURNAL OF SYNCHROTRON RADIATION, Issue 2 2001Kazumichi Sato A position-sensitive ionization chamber has been developed with backgammon-type-segmented electrodes. This novel detector possesses a linear range of 8 mm for determining the incident position of the X-ray beam incoming. The position resolution was found to be less than 10 µm, probably close the sub-micrometer region. Owing to its high spatial resolution, the position-sensitive ionization chamber was able to commit that the gradual decrease observed in the X-ray beam intensity at a SPring-8 beamline was mainly due to the spatial variation of the X-ray beam in time. The present work also confirmed the applicability of the novel detector to the accurate monochromator adjustment for experiments using diamond anvil cells. [source] In Vitro Degradation of Trimethylene Carbonate Based (Co)polymersMACROMOLECULAR BIOSCIENCE, Issue 9 2002Ana Paula Pêgo Abstract Trimethylene carbonate (TMC) was copolymerized with D,L -lactide (DLLA) or with , -caprolactone (CL), and the degradation of melt-pressed solid copolymer films in phosphate-buffered saline at pH 7.4 and 37,°C was followed for a period of over two years. The parent homopolymers were used as reference materials. The degradation profile of TMC-DLLA- and TMC-CL based copolymers was similar and was best described by autocatalyzed bulk hydrolysis, preferentially of ester bonds. The hydrolysis rates varied by two orders of magnitude, depending on polymer composition and physical characteristics under the degradation conditions. TMC-DLLA copolymers degraded faster than the parent homopolymers. The copolymers lost their tensile strength in less than five months, after which mass loss occurred. Copolymers with 50 or 80 mol-% of TMC underwent total degradation in eleven months. For TMC-CL copolymers, a slow and gradual decrease in molecular weight and deterioration of the mechanical performance was observed. These copolymers maintained suitable mechanical properties for seventeen months or longer. Chain scission in the semicrystalline copolymers resulted in an increase in crystallinity. In comparison with the CL homopolymer, the introduction of a small amount of TMC (10 mol-%) significantly reduced the increase in crystallinity during degradation. Poly(TMC) specimens were dimensionally stable and showed a negligible decrease in molecular weight. A 60% decrease in the initial tensile strength of the polymer samples was observed after two years. [source] Amplified fragment length polymorphism (AFLP) markers reveal that population structure of triploid dandelions (Taraxacum officinale) exhibits both clonality and recombinationMOLECULAR ECOLOGY, Issue 1 2000R. G. M. Van Der Hulst Abstract Highly variable amplified fragment length polymorphism (AFLP) fingerprints of triploid apomictic dandelions obtained from three localities in an area where diploids are lacking were analysed to infer the predominant modes of reproduction. The distribution of markers was analysed using character compatibility to infer whether many genotypes agree with a tree-like structure in the data set. The presence of incompatible character state combinations (matrix incompatibility; MI) was used as a measure of genetic exchange. The detection of overrepresented genotypes, of which some were widespread, confirmed asexual reproduction. Not all genotypes were overrepresented; approximately half of the genotypes in the three localities were found only once. Because, in terms of genotype frequencies, only a part of the genetic variation is described, more important aspects of the molecular data such as relationships between markers or genotypes have been studied. The analysis of character compatibility indicated a disagreement of the data with a clonal structure. Nearly all genotypes contributed to MI and this contribution varied considerably among genotypes in each sampled locality. A gradual decrease of matrix incompatibility upon successive deletion of genotypes showing the highest contribution to MI indicated that marker distribution of virtually all genotypes disagreed with a tree-like structure in the data. This result suggested that many genotypes were separated by one or more sexual generations. Consistent with this conclusion was the fact that markers that show a low probability of contributing to MI are different in every sampled locality, which is most easily explained as the result of recombination. Apparently, asexual reproduction has resulted in overrepresented, widespread genotypes but sexual recombination has also substantially contributed to genetic variation in the sites studied. [source] Investigation of estrogen receptor , and , mRNA expression in the pregnant rat uterusMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 4 2004Renáta Minorics Abstract Although the expressions of the estrogen receptor (ER) subtypes have been demonstrated in a large number of estrogen target tissues, to date no evidence has been reported as to how the expressions of the alpha (,) and beta (,) ER subtype mRNA alter in the rat uterus during pregnancy. The aims of the present study were to obtain information concerning the changes in the ER and the progesterone receptor (PR) in early pregnancy and to determine the alterations in the ER subtype mRNA in the pregnant rat uterus. To demonstrate the ER and PR densities, radioligand saturation assay was used. The reverse-transcription-polymerase chain reaction (RT-PCR) was applied to characterize the alterations in the ER subtype mRNA. ER expression was highest on day 5 of pregnancy (Bmax,=,637.40,±,76.10 fmol/mg). The PR expression did not change significantly until day 8, but the protein density was increased on day 8 of pregnancy. The ER, mRNA expression was active during pregnancy, maximum expression was attained on day 5; a gradual decrease was then observed until the second half of pregnancy when its expression continuously increased up to the day of labor (day 22). Since the attachment of the blastocyst, an event that is dependent on estradiol in the progesterone-primed uterus of the rat, occurs on day 5 of pregnancy and the levels of the ER protein and the ER, mRNA on day 5 of pregnancy was the highest, it could be supposed that this subtype of ER might regulate implantation. The ER, mRNA was detected only from day 7 to day 15, with a maximum level on day 8. The expression of this ER subtype might be related to the development of decidual tissue. Mol. Reprod. Dev. 68: 463,468, 2004. © 2004 Wiley-Liss, Inc. [source] ZnO nanocrystallites obtained by oxidation of zinc arachidate , arachidic acid composite multilayersPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 6 2007Sukhvinder Singh Abstract ZnO nanocrystallites were prepared by the oxidation of Zinc Arachidate,Arachidic Acid (ZnA,AA) composite multilayers grown on quartz and freshly cleaved mica substrates. Control of zinc content in the multilayers was achieved by the manipulation of the subphase pH and the variation in the number of monolayers transferred. FTIR studies of multilayers show a gradual decrease in ZnA content as the subphase pH is reduced. X-ray reflection studies show the presence of a single layered structure in all the as-deposited multilayers transferred at different subphase pH. These observations suggest molecular level mixing of ZnA and arachidic acid molecules. The precursor multilayers were oxidized in the temperature range of 100,700 °C. The formation of ZnO is confirmed by UV,Visible spectroscopy. Atomic force micrographs show that the oxidation treatment resulted in either large agglomerates of ZnO nanocrystallites or isolated nanocrystallites, depending on the zinc content of the precursor multilayers. Typically, 7 monolayers ZnA,AA transferred at subphase pH of 5.0 on mica and oxidized at 700 °C resulted in uniformly distributed, isolated and nearly mono-dispersed nanocrystallites of size 11 ± 3 nm. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Is there an elephant in the room?AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 5 2007Addressing rival approaches to the interpretation of growth perturbations, small size Two interpretations of growth perturbation and small size are commonly applied in human biology: an adaptationist approach in which small size is considered to be an a relatively beneficial adjustment to environmental stressors, and a biomedical approach in which small size is considered nonadaptive, a sign of dysfunction or pathology. These two interpretations conflict, but are used without acknowledging or addressing the conflict. This article reviews the strengths and weaknesses of the two. This exercise does not prove the indisputable superiority of either approach. Considerations of epistemology show that biologists will never be faced with a decisive test of either, much as they might like such clear cut evidence. Nevertheless, it is possible that a gradual decrease in the productivity of one approach will become a sufficient reason to abandon it. Alternatively, if specific areas of application can be distinguished, each approach might continue to be productive in its own domain. Am. J. Hum. Biol., 2007. © 2007 Wiley-Liss, Inc. [source] Plastid differentiation and chlorophyll biosynthesis in different leaf layers of white cabbage (Brassica oleracea cv. capitata)PHYSIOLOGIA PLANTARUM, Issue 3 2004Katalin Solymosi The contents of protochlorophyllide, protochlorophyll and chlorophyll together with the native arrangements of the pigments and the plastid ultrastructure were studied in different leaf layers of white cabbage (Brassica oleracea cv. capitata) using absorption, 77 K fluorescence spectroscopy and transmission electron microscopy. The developmental stage of the leaves was determined using the differentiation of the stoma complexes as seen by scanning electron microscopy and light microscopy. The pigment content showed a gradual decrease from the outer leaf layer towards the central leaves. The innermost leaves were in a primordial stage in many aspects; they were large but had typical proplastids with few simple inner membranes, and contained protochlorophyllide and its esters in a 2 : 1 ratio and no chlorophyll. Short-wavelength, not flash-photoactive protochlorophyllide and/or protochlorophyll forms emitting at 629 and 636 nm were dominant in the innermost leaves. These leaves also had small amounts of the 644 and 654 nm emitting, flash-photoactive protochlorophyllide forms. Rarely prolamellar bodies were observed in this layer. The outermost leaves had the usual characteristics of fully developed green leaves. The intermediary layers contained chlorophyll a and chlorophyll b besides the protochlorophyll(ide) pigments and had various intermediary developmental stages. Spectroscopically two types of intermediary leaves could be distinguished: one with only a 680 nm emitting chlorophyll a form and a second with bands at 685, 695 and 730 nm, corresponding to chlorophyll,protein complexes of green leaves. In these leaves, a large variety of chloroplasts were found. The data of this work show that etioplasts, etio-chloroplasts or chloro-etioplasts as well as etiolated leaves do exist in the nature and not only under laboratory conditions. The specificity of cabbage leaves compared with those of dark-grown seedlings is the retained primordial or intermediary developmental stage of leaves in the inner layers for very long (even for a few month) period. This opens new developmental routes leading to formation of specially developed plastids in the various cabbage leaf layers. The study of these plastids provided new information for a better understanding of the plastid differentiation and the greening process. [source] Progressive neuronal degeneration of childhood: prenatal diagnosis by MRIPRENATAL DIAGNOSIS, Issue 4 2005Jocelyne de Laveaucoupet Abstract We report two cases in the same family of progressive neuronal degeneration of childhood,Alpers syndrome,with prenatal MRI findings in one case. The first infant presented at birth with severe microcephaly, then rapidly evolved to progressive encephalopathy with refractory epilepsy, leading to death at 10 months. Biochemical investigations including liver function tests were normal. CT and MRI showed severe diffuse brain atrophy. The diagnosis of progressive neuronal degeneration of childhood was made on the clinical and imaging data. The second pregnancy was marked by gradual decrease of fetal cerebral biometry and a prenatal MRI performed at 32 weeks showed diffuse cortical atrophy, as observed in the sibling. The infant died at 5 months. Neuropathological findings were consistent with Alpers syndrome. Copyright © 2005 John Wiley & Sons, Ltd. [source] Obstructive infertility: changes in the histology of different regions of the epididymis and morphology of spermatozoaANDROLOGIA, Issue 4 2006P. C. Pal Summary In the present study, the effects of prolonged obstruction in different regions of the human epididymis on its histology and on the spermatozoa retained at the site of obstruction were assessed. Men who were confirmed of having obstruction of the epididymis underwent vasoepididymostomy (VEA) for surgical correction of the obstruction. At the time of surgery, fluid from the epididymal tubule above the site of obstruction was aspirated and examined for sperm profile. Epididymal tissue, collected at the site of obstruction, was processed for assessment of histological changes and also used to identify the site of obstruction. Prolonged obstruction of the epididymis has caused degeneration of the epididymal epithelium, gradual decrease in the diameter of the tubule and tubular lumen and increase in the intertubular connective tissue. Sperm aspirated from the caput epididymal fluid showed sluggish pattern of motility only in one out of the six subjects, whereas spermatozoa collected from the cauda epididymal fluid showed rapid linear progressive motility in one of three subjects. A major percentage of spermatozoa in the aspirated fluid showed various types of morphological abnormalities, irrespective of the site of obstruction. These results are discussed in relation to the role of the epididymis in investing spermatozoa with motility and fertilizing capacity. [source] The antioxidant capacity response to hypoxia stress during transportation of characins (Hyphessobrycon callistus Boulenger) fed diets supplemented with carotenoidsAQUACULTURE RESEARCH, Issue 7 2010Chih-Hung Pan Abstract This study aimed to determine whether dietary carotenoid (CD) supplements could affect the antioxidant capacity of characins Hyphessobrycon callistus upon hypoxia stress at live transportation. Two types of CD [astaxanthin (AX), ,-carotene (BC)] and their 1:1 combination (MX) at three concentrations (10, 20 and 40 mg kg,1) were supplemented, resulting in nine CD diets. After 8 weeks' rearing, the resulting fish were divided into two subgroups and exposed to hypoxia or normoxia. Hypoxia involved a gradual decrease in dissolved oxygen (DO) from 6.5 to <1.0 mg L,1. Normoxia was DO kept in saturation. Hypoxia led to an increase in the total antioxidant status (TAS), superoxide dismutase (SOD), glutathione peroxidases (GPx) and aspartate aminotransferase (AST) activity of blood serum in fish, but had no effect on alanine aminotransferase (ALT). Under hypoxia, fish fed CD diets had lower SOD, GPx and ALT activity than control fish, showing that dietary CD could increase the antioxidant capacity and protection of the liver. Dietary AX was more effective for antioxidant capacity than BC and MX when under hypoxia stress, because GPx, ALT and AST were lower in AX-fed fish. Except TAS, the other four enzyme activities showed decreasing trends with increasing dietary CD concentrations. [source] | ||||||||||||||||||||||