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Subsequent Growth (subsequent + growth)
Selected AbstractsVenture Creation Speed and Subsequent Growth: Evidence from South AmericaJOURNAL OF SMALL BUSINESS MANAGEMENT, Issue 3 2010Joan-Lluis Capelleras Though time is an important dimension of the venture creation process, our understanding of why some entrepreneurs are able to act more quickly than others is limited. Equally, not much is known about the relationship between venture creation speed and the subsequent venture growth. In this paper, we use a resource-based perspective to provide insights into the factors that quicken or retard venture creation and to explore how speed impacts on subsequent growth. This is important because the topic remains generally underresearched and because even less is understood about venture creation speed in the context of South American economies. Data were collected from face-to-face interviews with 647 entrepreneurs in Argentina, Brazil, Chile, and Peru. Using a multivariate regression framework, we find that entrepreneurs make use of their human and social capital resources to shape the speed by which their venture is created. Moreover, their perceptions of unfavorable environmental conditions seem to retard venture creation. Findings also suggest that entrepreneurs who take more time to create a more solid resource base tend to receive better growth outcomes. Implications from the findings are discussed. [source] Short-term dominance: stability and consequences for subsequent growthJOURNAL OF FISH BIOLOGY, Issue 10 2009K. Tiira Dominance status was determined among groups of four fish by using individuals from eight brown trout Salmo trutta populations. Subsequent growth of the fish was later recorded in larger groups. Seven months after the first set of trials, an additional set of dominance trials was performed by using the same fish. Social status affected subsequent growth; individuals having the lowest ranks grew less when compared to the higher ranking fish. Furthermore, the short term dominance hierarchy was rather stable between the two trials. This was especially the case with the lowest ranking fish, which tended to remain in the lowest position also in the second trial. The results suggest that the short term dominance trials done among few conspecifics reflect relatively well not only the subordinates' relative but also absolute social status. [source] Thick crack-free AlGaN films deposited by facet-controlled epitaxial lateral overgrowthPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2003R. Liu Abstract Thick crack-free AlGaN films have been grown on inclined-facet GaN templates. Light emitting diodes with , = 323 nm has been achieved on these epilayers. The GaN template was grown at a low temperature in order to obtain triangle-facet growth fronts. Subsequent growth of AlGaN on this template involving a lateral overgrowth process exhibits interesting properties. The microstructure and optical characterizations were done using transmission electron microscopy and cathodoluminescence. At the AlGaN/GaN interface, a high density of dislocations was created due to lattice mismatch strain. Another unexpected set of triangular boundaries was observed inside the AlGaN layer, which grew without any change of the growth parameters. These boundaries were found to arise from domains grown in different directions. Mono-chromatic cathodoluminescence images indicate that Al content is different between the vertically-grown and the laterally-grown domains, suggesting that lattice mismatch strain exists between them. Dislocations were created at these mismatched boundaries to relax the strain. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Abnormal fetal aortic velocity waveform and postnatal growthACTA PAEDIATRICA, Issue 11 2000D Ley Postnatal growth from birth up to 7 y of age was evaluated in 151 children with varying degrees of intrauterine growth retardation who were previously examined in their intrauterine life with Doppler velocimetry of the thoracic descending aorta. The children with abnormal fetal aortic blood flow class (BFC), of which 39/46 (85%) had a birthweight 2 SD below the mean of the population, were lean at birth and had a high rate of catch-up growth in weight and length during the first 3 and 6 mo, respectively. After the initial phases of rapid catch-up in weight and length, mean values of SD scores for weight and height remained relatively unchanged up until 2 y of age, thereafter increasing gradually up to 7 y of age, leaving 4/46 (8%) and 4/46 (8%) below ,2 SD for weight and height, respectively. The pattern of changes in length/height and weight over time did not differ between those infants with abnormal BFC and those with normal BFC. The abnormal fetal aortic waveform was not related to rate of early catch-up growth or to height or weight at 7 y of age after adjustment for deviation in growth at birth. The magnitude of deficit in weight and length at birth was more predictive of subsequent growth. [source] Lack of Interaction between Extreme High-Temperature Events at Vegetative and Reproductive Growth Stages in WheatJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 3 2003B. Wollenweber Abstract Increased climatic variability and more frequent episodes of extreme conditions may result in crops being exposed to more than one extreme temperature event in a single growing season and could decrease crop yields to the same extent as changes in mean temperature. The developmental stage of the crop exposed to increased temperatures will determine the severity of possible damage experienced by the plant. It is not known whether or not the damaging effects of heat episodes occurring at different phenological stages are additive. In the present study, the interaction of high-temperature events applied at the stages of double ridges and anthesis in Triticum aestivum (L.) cv. Chablis was investigated. Biomass accumulation of control plants and that of plants experiencing high temperatures during the double-ridge stage were similar and were reduced by 40 % when plants were subjected to a heat event at anthesis. Grain number on the main and side tillers declined by 41 %, and individual grain weight declined by 45 % with heat stress applied at the double-ridge stage and anthesis or at anthesis alone. The harvest index was reduced from 0.53 to 0.33. Nitrogen contents in leaves were reduced by 10 % at the double-ridge stage and by 25 % at anthesis. The maximum rates of CO2 assimilation increased with heat stress at the double-ridge stage and higher rates were maintained throughout the growing season. The results clearly indicate that an extreme heat event at the double-ridge stage does not affect subsequent growth or the response of wheat to heat stress at anthesis. [source] The role of retinoic acid in the morphogenesis of the neural tubeJOURNAL OF ANATOMY, Issue 4 2003L. Wilson Abstract We have examined the role of the signalling molecule, retinoic acid, in the process of neurulation and the subsequent growth and differentiation of the central nervous system using quail embryos that have developed in the absence of retinoic acid. Such retinoic acid-free embryos undergo abnormal neural tube formation in terms of its shape and structure, but the embryos do not display spina bifida or exencephaly. The neural tubes have a wider floor plate, a thicker roof plate and a different dorsoventral shape. Phalloidin staining and electron microscopy revealed alterations in the actin filaments and the junctional complexes of the cell layer lining the lumen. Initially the neural tubes proliferated at the same rate as normal, but later the proliferation rate declined drastically and neuronal differentiation was highly deficient. There were very few motoneurons extending neurites into the periphery, and within the neural tube axon trajectories were chaotic. These results reveal several functions for retinoic acid in the morphogenesis and growth of the neural tube, many of which can be explained by defective notochord signalling, but they do not suggest that this molecule plays a role in neural tube closure. [source] Nesting behavior and breeding success of HoatzinsJOURNAL OF FIELD ORNITHOLOGY, Issue 4 2007Antje Müllner ABSTRACT Hoatzins (Opisthocomus hoazin) are the only member of the family Opisthocomidae and are found only in forests in the Amazon and Orinoco river basin of South America. Although locally common in riparian habitats, information about their natural history is based almost exclusively on observations from gallery forests in the "llanos" (savannahs) of Venezuela. We investigated the nesting activities of Hoatzins in a primary rainforest in Amazonian Ecuador from 1995 to 2000. At our study site, Hoatzins live and breed in the inundated forests that surround lakes and river channels. Egg laying occurred from February to July and from September to November, but always peaked in April, May, and June. The mean clutch size was 2.4 ± 1.1 eggs (N= 291; range = 1,7), but 51% of all clutches contained two eggs. The mean duration of the incubation period was 32 ± 1.5 d (N= 20) and, overall, 17% of Hoatzin nests fledged at least one young. The main cause of nest failure was predation, with birds and snakes being the most frequent predators. Hoatzin reproduction was closely linked to the rainy season, and such timing may be influenced by increased food availability (high water levels cause leaf fall and the subsequent growth of new leaves coincides with the beginning of the feeding period of the young) and reduced risk of nest predation by mammalian predators when water levels are high. Our results indicate that the breeding biology of Hoatzins in tropical rainforest habitat, including small clutch sizes and low annual reproductive success, is similar to that of tropical passerines and provides further support for the existence of typical life history characteristics for tropical birds. SINOPSIS Las hipótesis relacionadas con la variación altitudinal en los ciclos de vida de aves están basadas en una gran cantidad de datos de aves de zona templada, mientras que para el trópico inclusive se desconoce la biología básica. Esto aplica en particular para aves que no son paserinos. Investigamos las actividades de anidamiento de Hoatzin (Opisthocumus hoazin) en un bosque pluvial primario de la amazonia ecuatorial. En nuestra área de estudio, los hoatzines viven y se reproducen en bosques inundados que bordean lagos y canales. Los intentos reproductivos estuvieron asociados a la época de lluvias y se agruparon en unos meses del año. Normalmente, estas aves anidan una vez al año. El reanidamiento solo ocurrio cuando hubo pérdidas durante la época de puesta. Los nidos fueron construidos en los árboles y arbustos más comunes en el hábitat. El número de huevos por camada vario de uno a siete, aunque el 51% de las camadas consistieron de dos huevos. El tiempo promedio de incubación fue de 32 días. El exito promedio de eclosionamiento (para todos los nidos) fue de 34% y el 50% de los pichones dejaron el nido, lo que dio un éxito de anidamiento en general de 17%. La causa principal de pérdida de nidos lo fue la depredación, en donde otras aves y culebras resultaron ser los principales depredadores. La pequeña ventana de tres meses para reproducirse parece ser el resultado de un fuerte constreñimiento para una reproducción exitosa, debido a una mejor protección de los nidos y mayor abundancia de alimentos durante la época de inundación. El hoatzin exhibe un ciclo de vida similar al de paserinos tropicales. Esto indica la efectividad de las presiones ambientales de selección que deben estar envueltas en la formación de dichos trasos. [source] Short-term dominance: stability and consequences for subsequent growthJOURNAL OF FISH BIOLOGY, Issue 10 2009K. Tiira Dominance status was determined among groups of four fish by using individuals from eight brown trout Salmo trutta populations. Subsequent growth of the fish was later recorded in larger groups. Seven months after the first set of trials, an additional set of dominance trials was performed by using the same fish. Social status affected subsequent growth; individuals having the lowest ranks grew less when compared to the higher ranking fish. Furthermore, the short term dominance hierarchy was rather stable between the two trials. This was especially the case with the lowest ranking fish, which tended to remain in the lowest position also in the second trial. The results suggest that the short term dominance trials done among few conspecifics reflect relatively well not only the subordinates' relative but also absolute social status. [source] Characteristics of egg and larval production in captive bluespotted gobiesJOURNAL OF FISH BIOLOGY, Issue 5 2001L. A. Privitera Spawning of the Hawaiian coral-reef goby Asterropteryx semipunctata was diurnal, occurring at various times throughout the day. Mean length of eggs deposited in nests was 0·76 mm (range 0·67,0·84); mean egg width was 0·47 mm (range 0·41,0·52). Clutch size varied from 296 to 1552 eggs (mean=886±309), and was independent of standard length, total body weight, and body condition. Mean relative clutch size was 1·59 eggs mg -1 total body weight (range 0·84,2·43). Clutches hatched 4,5 nights after being deposited in a nest. Mean notochord length of newly-hatched larvae was 1·88 mm (range 1·60,2·04). The minimum period of time that elapsed between egg deposition and subsequent growth of a new batch of oocytes to spawning size was 5,6 days, providing a reasonable estimate of minimum spawning interval. Compared with other gobiids, tropical species tend to have shorter incubation periods, smaller eggs and smaller larvae at hatching. [source] ACID TOLERANCE OF ESCHERICHIA COLI FOLLOWING COLD SHOCK TREATMENTJOURNAL OF FOOD SAFETY, Issue 2 2003GREG BLANK ABSTRACT The effect of an initial cold shock treatment (2 h at 10C), following an abrupt downshift in temperature from 37 to 10C, on the subsequent growth and survival of Escherichia coli strains O157:H7 and MY20 (Biotype 1) in acidified Trypticase soy broth (TSB) and fruit juices (orange, apple) was investigated. Overall, no difference in growth at 37C was observed between each cold shocked and noncold shocked E. coli strain when cultured in TSB adjusted with either acetic acid (pH 6.0)or malic, citric and tartaric acid (each adjusted to: pH 4.5, 5.0, 5.5, 6.0). However, significant (P ± 0.05) differences in survival were observed between cold shocked and noncold shocked populations in TSB acidified with acetic acid (pH 5.0) or citric, malic and tartaric acid (pH 4.0). For strain MY20, survivor levels for cold shocked cells in TSB acidified with acetic acid citric, malic and tartaric acid at 8C were significantly (P ± 0.05) higher than in noncold shocked populations. Also, at 37C survival levels for cold shocked cells were significantly (P ± 0.05) higher than noncold shocked cells in TSB acidified with either malic or tartaric acid (pH 4.0). For the O157:H7 strain, survivor levels were higher (P ± 0.05) for cold shocked cells when maintained in TSB at 37C regardless of acid type. At 8C, cold shock treatment only increased (P ± 0.05) the survival of the O157:H7 strain in TSB adjusted with acetic acid (pH 6.0). Acid cross protection induced by cold shocking, as evidenced by enhanced survival, was not apparent for either E. coil strain in apple (pH 3.5) or orange juice (pH 3.8) maintained at 8C. [source] The effects of RANK blockade and osteoclast depletion in a model of pure osteoblastic prostate cancer metastasis in boneJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 6 2005Peter G. Whang Abstract Adenocarcinoma of the prostate exhibits a clear propensity for bone and is associated with the formation of osteoblastic metastases. It has previously been suggested that osteoclast activity may be necessary for the development of these osteoblastic metastases based on data from lytic and mixed lytic-blastic tumors. Here we investigate the effects of complete in vivo osteoclast depletion via the blockade of receptor activator of NF:,B (RANK) on the establishment and progression of purely osteoblastic (LAPC-9 cells) bone lesions induced by human prostate cancer cells using a SCID mouse intratibial injection model. The subcutaneous administration of the RANK antagonist (15 mg/kg) RANK:Fc did not prevent the formation of purely osteoblastic lesions, indicating that osteoclasts may not be essential to the initial development of osteoblastic metastases. However, RANK:Fc protein appeared to inhibit the progression of established osteoblastic lesions, suggesting that osteoclasts may be involved in the subsequent growth of these tumors once they are already present. In contrast, RANK:Fc treatment effectively blocked the establishment and progression of purely osteolytic lesions formed by PC-3 cells, which served as a positive control. These results indicate that in vivo RANK blockade may not be effective for the prevention of osteoblastic metastasis but may potentially represent a novel therapy that limits the growth of established metastatic CaP lesions in bone. © 2005 Published by Elsevier Ltd. on behalf of Orthopaedic Research Society. [source] Venture Creation Speed and Subsequent Growth: Evidence from South AmericaJOURNAL OF SMALL BUSINESS MANAGEMENT, Issue 3 2010Joan-Lluis Capelleras Though time is an important dimension of the venture creation process, our understanding of why some entrepreneurs are able to act more quickly than others is limited. Equally, not much is known about the relationship between venture creation speed and the subsequent venture growth. In this paper, we use a resource-based perspective to provide insights into the factors that quicken or retard venture creation and to explore how speed impacts on subsequent growth. This is important because the topic remains generally underresearched and because even less is understood about venture creation speed in the context of South American economies. Data were collected from face-to-face interviews with 647 entrepreneurs in Argentina, Brazil, Chile, and Peru. Using a multivariate regression framework, we find that entrepreneurs make use of their human and social capital resources to shape the speed by which their venture is created. Moreover, their perceptions of unfavorable environmental conditions seem to retard venture creation. Findings also suggest that entrepreneurs who take more time to create a more solid resource base tend to receive better growth outcomes. Implications from the findings are discussed. [source] Orientation of Syndiotactic Polystyrene Crystallized in Cylindrical NanoporesMACROMOLECULAR RAPID COMMUNICATIONS, Issue 3 2009Hui Wu Abstract Syndiotactic polystyrene (sPS) nanorods with different diameters have been prepared by using anodic aluminum oxide templates, and the orientation of the sPS crystals in the nanorods has been investigated by FT-IR spectroscopy. It is found that the c axis of the ,, crystals preferentially oriented perpendicular to the axis of the nanorod, and the degree of orientation is lower as the diameter of the nanorod decreases. This unexpected result is attributed to nuclei formed at the surface of the nanopores and their subsequent growth, in addition to the preferential growth compatible with the pore direction by the nuclei formed in the bulk film and in the nanorods. [source] Investigation on steam oxidation behaviour of TP347H FG Part 1: Exposure at 256 barMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 7 2005J. Jianmin Abstract The stainless steel TP347H FG is a candidate material for the final stage tubing of superheater and reheater sections of ultra supercritical boilers operated at steam temperatures up to 620°C in the mild corrosion environments of coal-firing. A series of field tests has been conducted with the aforementioned steel in coal-fired boilers and this paper focuses on the steam oxidation behaviour for specimens tested at various metal temperatures for exposure times of 7700, 23000 and 30000 hours as investigated by light optical and scanning electron microscopy. The oxide present on the specimens is a duplex oxide, where the outer layer consists of two sub-layers, an iron oxide layer and an iron-nickel oxide layer; the inner layer is chromium rich chromium-iron-nickel oxide. Microstructure examination showed that for all these samples the varying grain size of subsurface metal affected the oxide thickness, where the larger the metal grain size, the thicker the oxidation scale. This gave the appearance of uneven inner oxides with a varying pit thickness. Comparison of the pit thickness measurement and oxide composition reveals that the oxidation rate is fast during the initial oxidation stage, but the subsequent growth of oxide from further exposure is slower due to the formation of a healing layer consisting of chromium rich oxide near original alloy grain boundaries. At a temperature region above 600°C a thin oxide rich in chromium and manganese is sometimes formed. In addition precipitation of secondary carbides in the bulk metal also occurs at this temperature region. [source] Entrepreneurship and Post-socialist Growth,OXFORD BULLETIN OF ECONOMICS & STATISTICS, Issue 1 2005Daniel Berkowitz Abstract We use a rich regional data set to obtain a statistical characterization of the relationship between entrepreneurial activity and economic growth within post-Soviet Russia. Russia is a useful laboratory for evaluating links between entrepreneurial activity and growth because of the striking variation in initial conditions, the adoption of policy reforms, and entrepreneurial activity observed across its large number of regions in the early stages of transition. Russia has also experienced striking regional variation in subsequent growth. Conditional on variations in initial conditions and policy reform measures, regional entrepreneurial activity exhibits a statistically and quantitatively significant relationship with subsequent economic growth. [source] Prenatal and intrapartum events and sudden infant death syndromePAEDIATRIC & PERINATAL EPIDEMIOLOGY, Issue 1 2002Hillary S. Klonoff-Cohen Summary The purpose of this study was to evaluate specific pregnancy and labour and delivery events that may increase the risk of sudden infant death syndrome (SIDS). A matched case,control study was conducted in five counties in southern California, using California death certificate records. The sample consisted of 239 Caucasian, African,American, Hispanic and Asian mothers of SIDS infants and 239 mothers of control infants matched on sex, race, birth hospital and date of birth. Mothers participated in a detailed telephone interview and provided access to obstetric and paediatric records. More case than control mothers reported a family history of anaemia (OR = 2.12, P < 0.001). Placental abruptions were strongly associated with SIDS (unadjusted OR = 7.94, [95% CI 1.34,47.12]). There was an increased risk of SIDS death associated with maternal anaemia during pregnancy (OR = 2.51, [95% CI 1.25,5.03]), while simultaneously adjusting for maternal smoking during pregnancy, maternal years of education and age, parity, infant birthweight, gestational age, medical conditions at birth, infant sleep position and post-natal smoking. Interactions of anaemia and prenatal smoking as well as anaemia and post-natal smoking were not statistically significant. There were no other statistically significant differences between case and control mothers for pregnancy conditions, labour and delivery events (e.g. caesarean sections, anaesthesia, forceps) or newborn complications (e.g. nuchal cord, meconium aspiration). Anaemia and placental abruptions were significantly associated with an increased risk of SIDS; both are circumstances in which a fetus may become hypoxic, thereby compromising the subsequent growth, development and ultimate survival of the infant. [source] Influence of imidacloprid seed treatments on rice germination and early seedling growthPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 3 2008Mark M Stevens Abstract BACKGROUND: Seed treatments with the chloronicotinyl insecticide imidacloprid (Gaucho® 600 FS) were evaluated to determine whether differences in concentration and exposure regime influence the germination and early growth of rice. RESULTS: Continuous exposure to imidacloprid (4 days at 2000 mg AI L,1) significantly (P < 0.001) reduced normal germination by an average of 18% across the 15 cultivars examined. Nine days after sowing, plants showed no adverse effects from continuous imidacloprid treatment during germination, with shoot lengths and root system dry weights equalling, or occasionally exceeding (P < 0.05), those of untreated plants. Short-term imidacloprid exposure (2 h at 2000 mg L,1) at initial seed wetting did not affect germination (P > 0.05), and short-term (1 h) exposure of 48 h pregerminated seed to imidacloprid (2000 mg L,1) similarly had no significant effect on early subsequent growth. Plants arising from 48 h pregerminated seed exposed to imidacloprid (1 h) at concentrations up to 4000 mg L,1 immediately before sowing were not significantly different from control plants at either 9 or 25 days post-sowing. CONCLUSION: Results show that imidacloprid will have no adverse effects on plant growth if applied to pregerminated rice shortly before sowing. Continuous exposure of seed during germination had more pronounced effects, and the initial response of different cultivars was highly variable. Cultivars with high levels of sensitivity (such as IR72) require further testing before continuous exposure to imidacloprid during germination can be recommended. Copyright © 2007 Society of Chemical Industry [source] Capillary filling of single-walled carbon nanotubes with ferrocene in an organic solventPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 10 2008Hidetsugu Shiozawa Abstract Capillary reactions of single-walled carbon nanotubes have been investigated both in ferrocene-saturated acetone and in ferrocene vapor. The encapsulations of ferrocene are observed as subsequent growth of inner shell tubes. From Raman spectroscopy we show that the filling yield is about ten times higher with the vapor filling. The inner tube , outer tube pair distributions are identical for both converted samples and different to the one grown from the fullerene precursor. The largest assigned inner shell tube from ferrocene is (11,0), which is not available from the fullerene precursor. This result is attributed to the catalytic growth mechanism enabling a wide diameter range of inner shell tubes. The solvent based filling provides for a quick analysis of possible molecule guest , nanotube host pairs with a moderate filling factor. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Integration of CdSe quantum dots with GaN optoelectronic materialsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2005J. G. Pagan Abstract Material structures on the nanoscale can enable enhancement of optoelectronic device performance. For example, in the InGaN active layers of MOCVD grown blue light emitting diodes, indium segregation plays a critical role in the interplay between blue luminescent channels and non-radiative recombination centers such as crystal defects. Unfortunately, high efficiency luminescence of InGaN does not extend into the "deep green" spectral region, around the wavelength of peak human eye response. We are investigating whether commercially available luminescent nanostructures such as CdSe quantum dots can be incorporated into III-nitride devices to extend their high-efficiency performance into the "deep green". Surfactant stabilized CdSe particles in liquid dispersions are drop-cast onto HVPE grown GaN. Physical properties of resultant CdSe surface structures are examined. Luminescence is reported before and after subsequent growth of GaN. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Catch-up Growth or Regression to the Mean?AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 4 2005Recovery from Stunting Revisited An important question for policy is the extent to which catch-up growth can ease the impact of early stunting. Martorell et al. (1992) showed that stunted Guatemalan infants remain stunted into adulthood, whereas Adair (1999) found appreciable catch-up growth in Filipino children from 2,12 years. Both groups defined catch-up as an inverse correlation between early height and subsequent growth, but Martorell based the correlation on height, whereas Adair used height z scores. The statistical phenomenon of regression to the mean is much like catch-up growth, an inverse correlation between initial height and later height gain. The objective of this study was to reexamine the relationship between stunting and later catch-up growth in the context of regression to the mean. The design was a theoretical analysis showing that catch-up growth is more evident based on height z scores than on height, validated using data on 495 stunted South African children seen at 2 and 5 years of age. The correlation between height at 2 and height change from 2 to 5 was small based on height (,0.11) but large and highly significant based on height z score (,0.58), providing strong evidence of catch-up growth. We argue that catch-up growth should be estimated using height z score not height and that catch-up is present only when the change in z score exceeds that predicted by regression to the mean. This leads to a compact definition of catch-up growth: if z1 and z2 are the initial and final (mean) height z scores, and r is the correlation between them, then catch-up growth for groups or individuals is given by (z2 , rz1). Am. J. Hum. Biol. 17:412,417, 2005. © 2005 Wiley-Liss, Inc. [source] Reduced chilling tolerance in elongating cucumber seedling radicles is related to their reduced antioxidant enzyme and DPPH-radical scavenging activityPHYSIOLOGIA PLANTARUM, Issue 2 2002Ho-Min Kang Cucumber seedling radicles become more chilling sensitive as they elongate. Chilling seedlings with radicles 20 mm long for 48 h at 2.5°C inhibited subsequent growth by 36%, while it reduced the growth of 70 mm-long radicles by 63%. Although the growth rate of non-chilled cucumber radicles at 25°C is constant from 20 to 80 mm, tissue viability [i.e. reduction of TTC (2,3,5-triphenyltetrazolium chloride) to formazan] and DPPH (,,, -diphenyl- , -picrylhydrazyl) radical scavenging activity of apical tissue declines as radicles elongate from 20 to 80 mm in length. TTC reduction, DPPH-radical scavenging activity and protein content of apical tissue were higher in 20 than in 70 mm radicles immediately after chilling and after an additional 48 h of growth at 25°C. Catalase (CAT; EC 1.11.1.6) and ascorbate peroxidase (APX; EC 1.11.1.11) activity was higher in the apical tissue of 20 than in 70 mm radicles before chilling. Immediately after chilling and after an additional 48 h at 25°C, superoxide dismutase (SOD; EC 1.15.1.1), glutathione reductase (GR; EC 1.6.4.2), and guaiacol peroxidase (GPX; EC 1.11.1.7) activity increased more rapidly in 70 mm radicles than in 20 mm radicles (SOD, GR, and GPX activity in 70 mm radicles was 1.5-, 1.9- and 8.6-fold higher, respectively, than in 20 mm radicles). However, APX and CAT activity in 20 mm radicles were always higher than in 70 mm radicles. Growth after chilling enhanced the activity of all antioxidant enzymes compared to that found in non-chilled tissue; however, CAT activity in 70 mm radicles did not recover to levels found in non-chilled tissue. Higher levels of CAT, APX and DPPH-radical scavenging activity are correlated with higher chilling tolerance of 20 mm-long cucumber radicles compared to 70 mm-long radicles. [source] Influence of previous frost damage on tree growth and insect herbivory of Eucalyptus globulus globulusAUSTRAL ECOLOGY, Issue 5 2001Vivien P. Thomson Abstract The plant stress hypothesis suggests that some herbivores favour stressed plants, whereas the plant vigour hypothesis proposes that other herbivores prefer vigorous plants. The effects of a prior stress, that of frost damage, were examined on the subsequent growth of Eucalyptus globulus globulus and on the response of insect herbivores. Frost damage affected tree growth by reducing new leaf area and increasing specific leaf area (SLA). However, herbivore abundance was not affected by prior frost damage. Two feeding trials using Anoplognathus chloropyrus and Hyalarcta huebneri and a morphometric study of Ctenarytaina eucalypti were conducted to assess the performance of herbivores on trees that had suffered more or less frost damage. Consumption by A. chloropyrus and H. huebneri was unaffected by foliage origin (damaged versus healthy). Hyalarcta huebneri grew faster when fed leaves from previously damaged trees, and C. eucalypti from previously damaged trees were larger than those from healthy trees. Enhanced insect performance on frost damaged plants may have resulted from the high specific leaf area (most likely thinner) leaves. The herbivore abundance data did not support the hypothesis that previously frost damaged plants are preferred by insects. However, increased growth of H. huebneri and larger body size of C. eucalypti on damaged trees indicates that previously stressed trees may produce leaves of higher nutritional value. [source] Natural history, growth kinetics, and outcomes of untreated clinically localized renal tumors under active surveillanceCANCER, Issue 13 2009Paul L. Crispen MD Abstract BACKGROUND: The growth kinetics of untreated solid organ malignancies are not defined. Radiographic active surveillance (AS) of renal tumors in patients unfit or unwilling to undergo intervention provides an opportunity to quantify the natural history of untreated localized tumors. The authors report the radiographic growth kinetics of renal neoplasms during a period of surveillance. METHODS: The authors identified patients with enhancing renal masses who were radiographically observed for at least 12 months. Clinical and pathological records were reviewed to determine tumor growth kinetics and clinical outcomes. Tumor growth kinetics were expressed in terms of absolute and relative linear and volumetric growth. RESULTS: The authors identified 172 renal tumors in 154 patients under AS. Median tumor diameter and volume on presentation were 2.0 cm (mean, 2.5; range, 0.4-12.0) and 4.18 cm3 (mean, 20.0; range, 0.033-904). Median duration of follow-up was 24 months (mean, 31; range, 12-156). A significant association between presenting tumor size and proportional growth was noted, with smaller tumors growing faster than larger tumors. Thirty-nine percent (68 of 173) of tumors underwent delayed intervention, and 84% (57 of 68) were pathologically malignant. Progression to metastatic disease was noted in 1.3% (2 of 154) of patients. CONCLUSIONS: The authors demonstrated the association between a tumor's volume and subsequent growth, with smaller tumors exhibiting significantly faster volumetric growth than larger tumors, consistent with Gompertzian kinetics. Surveillance of localized renal tumors is associated with a low rate of disease progression in the intermediate term, and suggests potential overtreatment biases in select patients. Cancer 2009. © 2009 American Cancer Society. [source] Study of the Kinetics and Morphology of Gas Hydrate FormationCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 8 2006Abstract The kinetics and morphology of ethane hydrate formation were studied in a batch type reactor at a temperature of ca. 270,280,K, over a pressure range of 8.83,16.67,bar. The results of the experiments revealed that the formation kinetics were dependant on pressure, temperature, degree of supercooling, and stirring rate. Regardless of the saturation state, the primary nucleation always took place in the bulk of the water and the phase transition was always initiated at the surface of the vortex (gas-water interface). The rate of hydrate formation was observed to increase with an increase in pressure. The effect of stirring rate on nucleation and growth was emphasized in great detail. The experiments were performed at various stirring rates of 110,190,rpm. Higher rates of formation of gas hydrate were recorded at faster stirring rates. The appearance of nuclei and their subsequent growth at the interface, for different stirring rates, was explained by the proposed conceptual model of mass transfer resistances. The patterns of gas consumption rates, with changing rpm, have been visualized as due to a critical level of gas molecules in the immediate vicinity of the growing hydrate particle. Nucleation and decomposition gave a cyclic hysteresis-like phenomena. It was also observed that a change in pressure had a much greater effect on the rate of decomposition than it did on the formation rate. Morphological studies revealed that the ethane hydrate resembles thread or is cotton-like in appearance. The rate of gas consumption during nucleation, with different rpm and pressures, and the percentage decomposition at different pressures, were explained precisely for ethane hydrate. [source] Is there a relationship between Birthweight and subsequent growth on the development of Dental Caries at 5 years of age?COMMUNITY DENTISTRY AND ORAL EPIDEMIOLOGY, Issue 5 2010A cohort study Kay EJ, Northstone K, Ness A, Duncan K, Crean SJ. Is there a relationship between Birthweight and subsequent growth on the development of Dental Caries at 5 years of age? A cohort study. Community Dent Oral Epidemiol 2010; 38: 408,414. © 2010 John Wiley & Sons A/S Abstract,,, Objectives:, To examine the associations between childhood growth and the presence of dental caries at age 5. Methods:, Data from the Avon Longitudinal Study of Parents and Children (ALSPAC) a population-based, prospective cohort study were used. We enrolled 14 541 pregnancies, and a 10% sample of these were dentally examined and measured at 61 months of age. Birthweight was obtained from medical records, and birth length and birthweight were assessed by trained ALSPAC measurers. A number of social and lifestyle factors were treated as potential confounding factors. Results:, Of 985, children, 242 (24.6%) had caries at 61 months of age. After adjustment, increased weight at birth was associated with a small increased risk of caries at 61 months (OR: 1.08 (95% CI: 1.03, 1.13) per 100 g increase, P = 0.002). A similar association was noted with respect to increased length at birth. Current weight and height did not appear to be associated with caries risk. Children who had caries at 61 months had slower increases in weight and height between birth and 61 months than those without decay at 61 months. Conclusions:, The weak associations we have demonstrated between weight and length at birth and risk of caries at age 61 months cannot be considered causal, however, the relationship between the two variables warrants further investigation. [source] | ||||||||||||||||||||||||||||