Rate Of Increase In Size Research Articles

Natural History of Small Gastric Subepithelial Lesions Less than 20 mm: A Multicenter Retrospective Observational Study (NUTSHELL20 Study)

Background and Aim: Small gastric subepithelial lesions (SELs) are sometimes encountered in daily esophagogastroduodenoscopy (EGD) practice, but whether once-annual or twice-annual endoscopy can provide sufficient follow-up remains unclear. Because follow-up based on small-SEL characteristics is important, this study clarified the natural history of gastric SELs less than 20 mm. Methods: This retrospective multicenter observation study conducted at 24 Japanese hospitals during April 2000 to March 2020 examined small gastric SELs of ≤20 mm diameter. The primary outcome was the rate of size increase of those SELs detected using EGD, with growth times assessed irrespective of SEL pathological diagnoses. Results: We examined 824 cases with tumors of 1–5 mm diameter in 298 (36.2%) cases, 6–10 mm in 344 (41.7%) cases, 11–15 mm in 112 (13.6%) cases, and 16–20 mm in 70 (8.50%) cases. An increase of small gastric SELs was observed in 70/824 patients (8.5%). The SELs larger than 6 mm increased, even after 10 years. No-change and increasing groups had no significantly different malignant findings at diagnosis. In cases of gastrointestinal stromal tumors (GISTs), internal cystic change in endoscopic ultrasound (EUS) is a risk factor for an increased tumor size. The predictive tumor growth cutoff size at initial diagnosis was 13.5 mm. Conclusions: Small gastric SELs less than 20 mm have an approximately 8.5% chance of increase. Predictive markers for GIST growth are tumor size ≥13.5 mm and internal cystic change in EUS.

Interaction of aqueous suspensions of single-walled oxidized carbon nanotubes with inorganic and organic electrolytes

This article reports the colloidal behavior of the single-walled carbon nanotubes, SWCNT, decorated by COOH groups, in water. Energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA) methods were used to characterize the solid samples. The SWCNT suspension was characterized by dynamic light scattering (DLS) and transmission electron microscopy (TEM) methods, as well as taking into account the dependence of the electrokinetic potential ς on pH. The negatively charged particles with a diameter of an equivalent sphere about ≈200 nm possess a ς value of –48 mV at pH 5.7 ± 0.1. Deceleration of the reaction of cationic and anionic triphenylmethine dyes (methyl violet and nitrophenol violet, respectively) with hydroxide ion in the presence of the SWCNT was observed. This effect can be associated with a lower local concentration of hydroxide ion compared to the bulk phase owing to a substantially interfacial concentration of the COO– groups.Critical coagulation concentrations, CCC, in electrolytic solutions were determined using the rate of increase in size. Coagulation with different inorganic electrolytes demonstrated that the system under study obey the Schulze–Hardy rule. Comparison with the literature data allowed confirming that the CCC for NaCl can be an effective criterion of oxidation degree of the carbon materials of this type. The coagulating influence of surface-active organic cations, including dyes, is much expressed. Besides the overcharging of the negatively charged colloidal species by cetyltrimethylammonium bromide, the same effect was revealed in the case of the cationic dyes neutral red and methyl violet, and even for the Ca2+ and La3+ cations.Methylation of the carboxylic groups, COOH → COOCH3, of the SWCNT during 380 h, as well as heating up to 1000 °C results in a substantial and sometimes opposite changes in the CCC values for different electrolytes. Along with decreasing in the CCC for NaCl, an increase in the corresponding values for multi-charged cations was observed. This reveals the important role of the simultaneous interactions of multi-charged cations with several COOH (or COO–) groups in the case of the initial highly oxidized SWCNT, because this effect became less possible after methylation or removal of the carboxylic groups via heating. A substantial negative ς-potential in aqueous media of the colloidal particles of preheated, i.e, devoid of carboxylic groups SWCNT, allows expecting an alternative charging mechanism, characteristic of oil drops and gas bubbles.

A two-component dynamic stand model of natural thinning

Our investigation aims (1) to derive a dynamic model for mean volume and biomass growth projection over time, considering the competition-induced tree mortality (dynamic size-density model), (2) to design a compatible two-component modelling system composed of the dynamic size-density model and an appropriate density decrease function, and (3) to examine the applicability of this composite natural thinning model to describe the growth dynamics of even-aged coniferous and broadleaved stands.The stand growth projection system was formulated to include three dynamic equations: a density decrease model expressing the reduction in tree number with dominant height growth, and two dynamic size-density models, for mean stem volume and tree biomass respectively. Two size-density formulations (M1 and M2) were derived, each including one local (site- or stand-specific) and three global (common to all stands of the species) parameters. Model M1 suggests a polymorphic set of size-density curves, while model M2 describes size-density curves with variable asymptotes. The goodness-of-fit statistics showed that for radiata pine (Pinus radiata D. Don) and Scots pine (Pinussylvestris L.) datasets the three-model-system based on M1 performed better than the one based on M2. The growth trajectories of downy birch (Betula pubescens Ehrh.) and English oak (Quercus robur L.) stands were described only by model M2. The systems of projection equations explained more than 95% of the variation in most cases.The two-component modelling system is implicitly defined by the stand density and mean tree size (biomass and/or volume) values for a given dominant stand height and set of global model parameters; it does not require any additional stand variables, constants of contested universality or standard-base variable values. It uses stand dominant height as a proxy for time, and inclusion of this growth stage indicator enables the bidirectional dependence between stand density and tree size to be reflected. The composite natural thinning model estimates sets of polymorphic curves with multiple asymptotes. Together with the stand-specific rate of density decrease, this also yields the stand-specific rate of size increase over time and the reduction in tree number, thus enabling prediction of contrasting individual growth patterns of stands of similar initial densities. It accounts for the isometric relationship between plant volume and biomass and can be considered for incorporation as a principal component of a dynamic Stand Density Management Diagram.

Pulmonary Valve Replacement With Small Intestine Submucosa-Extracellular Matrix in a Porcine Model.

Prosthetic materials available for pediatric pulmonary valve replacement (PVR) lack growth potential, inevitably leading to a size mismatch. Small intestine submucosa-derived extracellular matrix (SIS-ECM) has been suggested to possess regenerative properties. We aimed to investigate its function and potential to increase in size as a PVR in a piglet. An SIS-ECM trileaflet valved conduit was designed. Hanford minipigs, n = 6 (10-34 kg), underwent PVR with an intended survival of six months, with monthly echocardiograms evaluating valve size and function. The conduit was excised for histologic analysis. Of the six, one was sacrificed at three months for midterm analysis, and one at month 3 due to endocarditis. The remaining four constituted the study cohort. The piglet weight increased by 186% (19.56 ± 10.22 kg to 56.00 ± 7.87 kg). Conduit size increased by 30% (1.42 ± 0.14 cm to 1.84 ± 0.14 cm; P < .01). The native right ventricular outflow tract increased by 43% and the native pulmonary artery by 84%, resulting in a peak gradient increase from 10.08 ± 2.47 mm Hg to 36.25 ± 18.80 mm Hg (P = .03). Additionally, all valves developed at least moderate regurgitation. Conduit histology showed advanced remodeling with myofibroblast infiltration, neovascularization, and endothelialization. The leaflets remodeled beginning at the base with the leaflet edge being less cellular. In addition to the known endocarditis, bacterial colonies were discovered within a leaflet in another. The SIS-ECM valved conduit implanted into a piglet demonstrated cellular infiltration with vascular remodeling and an increase in diameter. Conduit stenosis was a result of slower rates of size increase than native tissue. Suboptimal leaflet performance requires design modifications.

Effect of photoperiod on adult size and weight in Harmonia axyridis (Coleoptera: Coccinellidae)

Short photoperiods often accelerate preimaginal development in insects that overwinter as adults and thus ensure the timely development of the diapausing stage. However, fast development usually results in small adults with few reserves whereas successful overwintering is dependent on sufficient reserves of nutrients. Thus, an insect faces two opposite challenges: increase adult weight or speed up pre-adult development. One solution to this time-size trade-off is fast development resulting in relatively light-weight but not too small adults, which are able to survive if there is an early onset to winter and have the possibility of further increasing their weight if conditions in autumn remain favourable for longer than usual. To test this hypothesis, we determined the effect of different photoperiods (day lengths of 12 and 18 h at 20°C) on the duration of preimaginal development, size of emerging adults and dynamics of adult weight in Harmonia axyridis. The larvae reared under conditions tended to develop faster and invest resources in structural growth rather than in increasing weight: the daily rate of increase in size under a 12 h long photoperiod was greater than that under a 18 h long photoperiod, whereas the rate of gain in weight showed the opposite tendency. This resulted in a significant decrease in the weight /size ratio of emerging adults. However, their low initial nutritional status was partly compensated for by adult feeding: the relative gain in adult weight of short-day individuals was greater than that of the beetles that developed under long day conditions.

OC-061 Change in size of hepatic colorectal metastases after completion of chemotherapy is greater than during treatment, but doesn’t influence disease-free survival after resection

Introduction The aim of this study was to assess the change in size of colorectal liver metastases between post-chemotherapy imaging and liver resection and to measure potential associations of this change with disease-free survival. Method Analysis of a prospectively maintained database of patients undergoing liver resection for colorectal liver metastases between 2005 and 2012 was undertaken. Response to chemotherapy was assessed by RECIST criteria. Change in tumour size between completion of chemotherapy and liver resection was measured by comparing the maximum diameter of lesions determined by post-chemotherapy imaging and those determined by examination of the resected specimen. Results In 146 patients the median interval between post-chemotherapy imaging and liver resection was 10.4 weeks (7.1–17.6 weeks). During this period tumour diameter increased in 102 patients (69.9%) and decreased in 37 (25.3%) with a median change of +2.3% per week (–19.4 to +1624%). Tumour behaviour after completion of treatment was not associated with disease-free survival in patients who initially responded to chemotherapy (P = 0.591) or those with stable disease (P = 0.436). Among patients with progressive disease after completion of chemotherapy the median disease-free survival of patients who initially responded (26 months) was longer than in those with stable disease (7 months) (P = 0.002), but there was no association between the rate of increase in size and disease-free survival (P = 0.406). Conclusion Change in tumour size after completion of chemotherapy is variable and can be rapid, especially in patients who initially responded to treatment. It does not however appear to affect outcome and should not be considered an adverse factor when counselling patients. Disclosure of interest None Declared.

Multiple metabolic requirements for size homeostasis and initiation of division in Saccharomyces cerevisiae.

Most cells must grow before they can divide, but it is not known how cells determine when they have grown enough so they can commit to a new round of cell division. Several parameters affect the timing of initiation of division: cell size at birth, the size cells have to reach when they commit to division, and how fast they reach that size. We report that Saccharomyces cerevisiae mutants in metabolic and biosynthetic pathways differ in these variables, controlling the timing of initiation of cell division in various ways. Some mutants affect the size at birth, size at initiation of division, the rate of increase in size, or any combination of the above. Furthermore, we show that adenylate kinase, encoded by ADK1, is a significant determinant of the efficiency of size control mechanisms. Finally, our data argue strongly that the cell size at division is not necessarily a function of the rate cells increase in size in the G1 phase of the cell cycle. Taken together, these findings reveal an unexpected diversity in the G1 cell cycle phenotypes of metabolic and biosynthetic mutants, suggesting that growth requirements for cell division are multiple, distinct and imposed throughout the G1 phase of the cell cycle.

Pictures of an Invasion: English Holly (Ilex aquifolium) in a Semi-Natural Pacific Northwest Forest

English holly (Ilex aquifolium) is an increasingly common invader of west-side Pacific Northwest forests, but little sitescale information exists about the pattern and processes of this invasion. We comprehensively surveyed English holly in an 8.4 ha area of invaded forest at St. Edward State Park (WA), a largely native forest in the Seattle metropolitan area. We measured, mapped, aged, and removed all holly ≥ 1 cm basal diameter or > 1 m from the nearest sampled holly, and used these data to characterize the invading population and the course of the invasion. Holly in our sample (n = 466 known-age plants; 55.5 stems ha-1) ranged in age from 1 to 46 years. Trees ≥10 years old appeared to have very low mortality rates and exhibited accelerating rates of size increase and biomass accumulation with age. Native vegetation was greatly reduced under holly canopy. Our spatial and age data indicate that holly is proliferating and spreading rapidly at two scales: contiguous, primarily vegetative, expansion of tree clumps, and long distance dispersal via seed. Spread by both mechanisms appears to be accelerating, with population and canopy area both increasing approximately exponentially, having doubling times of approximately 6 and 5 years respectively. Projecting past spread patterns forward suggests that holly has the potential to soon become a prominent species both in number and canopy extent, likely at the expense of native plant diversity and forest structure. Based on these results, we offer recommendations for holly management in forested areas in the region.

Cytomechanical Perturbations during Low-Intensity Ultrasound Pulsing

To establish the therapeutic potential of low-intensity ultrasound, it is important to characterize its biophysical interactions with living cells. Here, through a series of single-cell direct observations, we show that low-intensity ultrasound pulsing would give rise to a dynamic course of cytomechanical perturbations at both the membrane and nucleus levels. Our investigation was conducted using a composite platform that coupled a 1-MHz ultrasound exposure hardware to a confocal microscopy system. Short ultrasound pulses (5 cycles, 2-kHz pulse repetition frequency) with a spatial-peak time-averaged intensity of 0.24 W/cm2 (0.85-MPa peak positive acoustic pressure) were delivered over a 10-min period to adherent Neuro-2a neuroblastoma cells, and live imaging of cellular dynamics was performed before, during and after the exposure period. Bright-field imaging results revealed progressive shrinkage of cellular cross-sectional area (25%–45%, N = 7) during low-intensity ultrasound pulsing; the initial rate of size decrease was estimated to be 8%–14% per minute. This shrinkage was found to be transient, as the sonicated cells had recovered (at a rate of size increase of 0.4%–0.9% per minute) to their pre-exposure size within 30 min after the end of exposure. Three-dimensional confocal imaging results further revealed that (i) ultrasound-induced membrane contraction was volumetric in nature (21%–45% reduction), and (ii) a concomitant decrease in nucleus volume was evident (12%–25% reduction). Together, these findings indicate that low-intensity ultrasound pulsing, if applied on the order of minutes, would reversibly perturb the physical and subcellular structures of living cells.

Biology, not environment, drives major patterns in maximum tetrapod body size through time

Abiotic and biological factors have been hypothesized as controlling maximum body size of tetrapods and other animals through geological time. We analyse the effects of three abiotic factors--oxygen, temperature and land area--on maximum size of Permian-Jurassic archosauromorphs and therapsids, and Cenozoic mammals, using time series generalized least-squares regression models. We also examine maximum size growth curves for the Permian-Jurassic data by comparing fits of Gompertz and logistic models. When serial correlation is removed, we find no robust correlations, indicating that these environmental factors did not consistently control tetrapod maximum size. Gompertz models--i.e. exponentially decreasing rate of size increase at larger sizes--fit maximum size curves far better than logistic models. This suggests that biological limits such as reduced fecundity and niche space availability become increasingly limiting as larger sizes are reached. Environmental factors analysed may still have imposed an upper limit on tetrapod body size, but any environmentally imposed limit did not vary substantially during the intervals examined despite variation in these environmental factors.

Condition, Survival, and Productivity of Elk (Cervus elaphus) in the Sacramento Mountains of Southern New Mexico

We radiotracked 23–63 adult female elk (Cervus elaphus) during 2003–2007 to determine whether condition (amount of body fat), survival of adults, or production and survival of juveniles was being impacted by habitat or other influences. Lactating females accrued relatively high levels of body fat (8.9–11.4%). Rates of survival of adult females were 0.95–1.00, rates of pregnancy were 0.87–0.96, and probability of pregnancy was most strongly related to mass, with larger females more likely to conceive. Preweaning (0.69–0.82), postweaning (0.58–0.87), and annual (0.44–0.71) rates of survival of juveniles varied among years. Excluding harvest, elk were able to achieve an annual rate of increase in size of population of 11–12%, which was limited only by survival of juveniles. Survival of juveniles was associated primarily with precipitation during gestation and parturition, indicating few constraints related to habitat.

MORPHOSTATISTICAL ANALYSIS OF MAASTRICHTIAN POPULATIONS OF GUEMBELITRIA FROM EL KEF, TUNISIA

Three species of Guembelitria with regular triserial arrangement are recognized in the late Maastrichtian, based on biometric measures of specimens from El Kef (Tunisia) and morphostatistical analysis. They are mainly recognized based on their test height and rate of increase in size of the chambers. Guembelitria blowi , nov. sp. is proposed for the short-spired morphotypes that were previously ascribed to Guembelitria trifolia. Guembelitria cretacea Cushman, 1933, is restricted to medium-spired morphotypes, and Guembelitria dammula Voloshina, 1961, to high-spired morphotypes. The three morphospecies have a papillate test surface, usually with pore-mounds, but some specimens exhibit imperforate papillae. The origin of this variability in the guembelitrid test surface might be linked to ecophenotypy or ontogeny, but the presence of cryptic species cannot be ruled out.

Dimensione e concentrazione dei gruppi bancari italiani nell'ultimo decennio

- The paper analyzes the change in the size distribution of Italian banking groups over the period 1999 to 2007 following a wave of M&amp;As among large banks. Had this process increased the degree of concentration we would have expected greater credit rationing for small firms, given the central role of Italian banks in financing small firms. We measure this change through widely used measures of concentration on branches. First, we observe a steady increase in concentration that can be captured only by looking at the overall size distribution. Other measures do not perceive this change until the year 2007, when the very large banks merged. Second, by focusing on the banking groups that have been active players in M&amp;As we do see a decline in concentration, since smaller players have caught up with the larger ones in terms of rate of size increase. This contrasts with the role of the new entries and the disappearance of banks following mergers, that has increased the dispersion of market shares. The implications are that: i) there is a credit termination risk due to the rise in active players' size, but ii) credit rationing may not occur due to a substitution effect in credit supply from new entries. Keywords: bank market structure; size distribution of banks; measures of concentration; credit rationing of SME; mergers and acquisitions Parole chiave: struttura dell'industria bancaria; distribuzione per dimensione delle banche; misure della concentrazione; razionamento del credito alle PMI; fusioni e acquisizioni Jel Classification: G21 - L11

The pattern of endocranial ontogenetic shape changes in humans

Humans show a unique pattern of brain growth that differentiates us from all other primates. In this study, we use virtual endocasts to provide a detailed description of shape changes during human postnatal ontogeny with geometric morphometric methods. Using CT scans of 108 dried human crania ranging in age from newborns to adults and several hundred landmarks and semi-landmarks, we find that the endocranial ontogenetic trajectory is curvilinear with two bends, separating three distinct phases of shape change. We test to what extent endocranial shape change is driven by size increase and whether the curved ontogenetic trajectory can be explained by a simple model of modular development of the endocranial base and the endocranial vault. The hypothesis that endocranial shape change is driven exclusively by brain growth is not supported; we find changes in endocranial shape after adult size has been attained and that the transition from high rates to low rates of size increase does not correspond to one of the shape trajectory bends. The ontogenetic trajectory of the endocranial vault analyzed separately is nearly linear; the trajectory of the endocranial base, in contrast, is curved. The endocranial vault therefore acts as one developmental module during human postnatal ontogeny. Our data suggest that the cranial base comprises several submodules that follow their own temporally and/or spatially disjunct growth trajectories.

On interfacial velocities during abnormal grain growth at ultra-high driving forces

Interfacial velocities during grain growth studies of nanocrystalline materials have been investigated. Two types of interfacial velocity parameters were developed in Ni and Ni–Co alloys. The first was a transformation-averaged parameter based on the time to consume the nanocrystalline matrix by abnormal grain growth. The second was a time-averaged parameter based on the rate of size increase of the largest growing grains. Despite the ultra-high driving force and rapid loss of nanostructure during annealing, the averaged grain boundary velocities are considerably lower than reported velocities during recrystallization in high purity systems for the same homologous temperature. It was found that the time-averaged abnormal growth front velocity decreased with increasing migration distance, which was interpreted in terms of a dynamic sulfur segregation model.

The 10-Year Natural History of Simple Renal Cysts

We previously reported the natural history of renal cysts, with a mean follow-up of 6 years. Here, we extended the follow-up period to 10 years. From January 1993 to August 2006, 61 patients diagnosed with renal cysts were followed for up to 14 years (mean 9.9 years). The sequential changes in renal cyst size were plotted against patient age, and the rate of increase in cyst size per year was calculated for each individual. Those cyst characteristics known to predict aggressiveness were analyzed. The majority of the cysts increased in size and number. The average size increase and the average rate of enlargement in all cysts were 1.6 mm and 3.9% per year, respectively. Several cysts, especially multiloculated cysts, increased rapidly during the first 2 to 3 years, but then the rate of growth tended to decelerate with time. By using univariate analyses, age, laterality and cyst shape were revealed to be significant predictors of aggressiveness. The multivariate analysis revealed that age was the most significant predictor. Renal neoplasms originating from the renal cysts appeared in 2 patients during the follow-up period. The rate of size increase of the neoplasm-bearing cysts was similar to that of the other benign renal cysts in the same age category. The simple renal cysts continued to increase in size over 10 years, and sometimes increased rapidly, especially in younger patients. However, their growth rates appeared to decrease with age. There seems to be no specific pattern observed in the neoplasm-bearing renal cysts.

Macroevolutionary trends in the Dinosauria: Cope's rule

Cope's rule is the tendency for body size to increase over time along a lineage. A set of 65 phylogenetically independent comparisons, between earlier and later genera, show that Cope's rule applied in dinosaurs: later genera were on average about 25% longer than the related earlier genera to which they were compared. The tendency for size to increase was not restricted to a particular clade within the group, nor to a particular time within its history. Small lineages were more likely to increase in size, and large lineages more likely to decrease: this pattern may indicate an intermediate optimum body size, but can also be explained as an artefact of data error. The rate of size increase estimated from the phylogenetic comparisons is significantly higher than the rate seen across the fauna as a whole. This difference could indicate that within-lineage selection for larger size was opposed by clade selection favouring smaller size, but data limitations mean that alternative explanations (which we discuss) cannot be excluded. We discuss ways of unlocking the full potential usefulness of phylogenies for studying the dynamics of evolutionary trends.

Use of otolith microstructure to study life history of juvenile chinook salmon in the Strait of Georgia in 1995 and 1996

The pattern of otolith daily increments was used to identify hatchery-reared, wild ocean-type and wild stream-type chinook and study their life history in the Strait of Georgia. In 1995 and 1996, almost all of hatchery-reared and wild stream-type chinook entered the Strait of Georgia in May and June, while wild ocean-type chinook entered from April to August. Upon ocean entry stream-type fish were the largest and wild ocean-type the smallest. Hatchery-reared and wild ocean-type chinook leaving fresh water later in the year were larger than those leaving earlier. The mean length of wild stream-type chinook was not related to the time of ocean entry. All the life history types maintained their size differences throughout the summer and fall despite some differences in rates of size increase. Hatchery-reared and wild stream-type chinook grew faster in 1995 than in 1996. Wild ocean-type grew at about the same rate. During early summer, the percentage of wild ocean-type chinook was low in contrast to the percentage of hatchery-reared and wild stream-type chinook in 1995 and 1996, respectively. In September of both years, the percentage of wild ocean-type chinook increased and the percentage of hatchery-reared and wild stream-type chinook dropped. By November in both years, the percentage of hatchery-reared chinook increased, especially in 1996 when the percentage exceeded 80%. After the first ocean winter, the percentage of hatchery-reared fish remained high.

Growth, nutrition, and blow fly parasitism in nestling Pied Flycatchers

The nutritional status of the host may play a major role in mediating the detrimental effects of parasites. We performed an experiment with the aim of determining whether increased food availability can compensate for the effects of ectoparasites on growth during the late nestling period, final size, and survival until fledging of Pied Flycatcher (Ficedula hypoleuca) nestlings. Nests were provided with supplementary food, treated with insecticide, given both treatments, or given neither treatment (control). Differences in the number of blood-sucking, ectoparasitic blow fly larvae (Protocalliphora azurea) occurred between treated nests. Nestlings in the group given supplementary food and with low numbers of parasites grew faster and had a higher haematocrit value than those in groups that were fumigated and given supplementary food, with nestlings from control nests attaining the lowest values. Nestling measurements did not differ between fumigated and food-supplemented groups. Although the final sizes attained did not differ among nestlings from the different experimental groups, there was a significant difference in the rates of increase in size among groups. Nestlings in nests fumigated and provided with extra food were (nonsignificantly) smaller and leaner than nestlings from the other groups at the beginning of the experiment, but were slightly larger and heavier (again nonsignificantly) at the end of the experiment. Thus, their growth was faster than that of the other groups. The results are discussed, highlighting problems related to the function linking intensity of parasit ism to host fitness and variation in external (climate, food) conditions.

Growth, nutrition, and blow fly parasitism in nestling Pied Flycatchers

The nutritional status of the host may play a major role in mediating the detrimental effects of parasites. We performed an experiment with the aim of determining whether increased food availability can compensate for the effects of ectoparasites on growth during the late nestling period, final size, and survival until fledging of Pied Flycatcher (Ficedula hypoleuca) nestlings. Nests were provided with supplementary food, treated with insecticide, given both treatments, or given neither treatment (control). Differences in the number of blood-sucking, ectoparasitic blow fly larvae (Protocalliphora azurea) occurred between treated nests. Nestlings in the group given supplementary food and with low numbers of parasites grew faster and had a higher haematocrit value than those in groups that were fumigated and given supplementary food, with nestlings from control nests attaining the lowest values. Nestling measurements did not differ between fumigated and food-supplemented groups. Although the final sizes attained did not differ among nestlings from the different experimental groups, there was a significant difference in the rates of increase in size among groups. Nestlings in nests fumigated and provided with extra food were (nonsignificantly) smaller and leaner than nestlings from the other groups at the beginning of the experiment, but were slightly larger and heavier (again nonsignificantly) at the end of the experiment. Thus, their growth was faster than that of the other groups. The results are discussed, highlighting problems related to the function linking intensity of parasit ism to host fitness and variation in external (climate, food) conditions.